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Coconut Oil: Chemistry and Nutrition

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 Coconut Oil
Chemistry and Nutrition
Copyright © 2016 Lakva Publishers
All rights reserved. No part of this publication may be
reproduced without prior written consent of the
copyright holder.

First Published 2016

ISBN 978-955-1605-36-0

Lakva Publishers.
Prof. Kapila N. Seneviratne, Ph. D. Chemistry: Coconut Oil/ K. N. Seneviratne, N. Jayathilaka
Battaramulla: Lakva Publishers, 2016
Director, Research and Consultation Center for
Page. 130 Pictures: 21 cm
Coconut Oil, University of Kelaniya, Sri Lanka
ISBN 978-955-1605-36-0 Price: Rs: 400.00
i. i. Book Name

Nimanthi Jayathilaka, Ph. D. 1. Chemistry

Department of Chemistry, University of Kelaniya,

Printed and Published by:- Lakva Publishers
Sri Lanka
Battaramulla

ii
Preface unsaponifiable fraction of oils due to antimicrobial,
anticancer and antioxidant properties. The lower incidence
of coronary heart disease in the Mediterranean region has
Coconut oil is one of the most widely used vegetable oils been hypothesized to be due to the protective effect of the
for several hundred years. However, coconut oil may also phenolic compounds present in olive oil. Similarly,
be considered as a cooking oil whose chemical and phenolic compounds present in the unsaponifiable fraction
nutritional aspects are least investigated. Most of the early of coconut oil are reported to be responsible for the
research about coconut oil was conducted in Western beneficial health effects such as inhibition of the oxidation
countries and the views presented over the health quality of of low-density lipoprotein (LDL) and lowering of serum
coconut oil are controversial. Even though the early views LDL levels.
regarding the coconut oil and heart disease are also
conflicting, the scientific opinion about coconut oil has This book details the well-established chemistry of the
changed dramatically during the last decade. main compounds of the saponifiable fraction and the most
recently investigated chemistry of the unsaponifiable
Most of the predictions and the interpretations of the phenolic fraction of coconut oil. In addition, the recent
nutritional quality of coconut oil are based on the fatty acid findings related to the antioxidants present in coconut oils
composition of coconut oil. Unrefined edible oils contain a extracted under different conditions and the antioxidant
saponifiable fraction or a fraction with an ester functional properties are also summarized.
group that can be hydrolyzed under basic conditions, which
amounts up to 98 % or more of the weight of the oil. This
fraction includes free fatty acids, triglycerides and all other Kapila N. Seneviratne and Nimanthi Jayathilaka
lipid forms.
12-02-2016
The chemistry of the saponifiable fraction of coconut oil is
well-known. However, the nutritional aspects of the
saponifiable fraction and scientific information about the
compounds present in unsaponifiable fraction of coconut
oil remains less explored. The unsaponifiable fraction
contains several polar and nonpolar organic compounds.
Even though this fraction is a minor fraction, it should not
be neglected when the nutritional quality of coconut oil is
evaluated. Phenolic compounds are among the most
nutritionally important compounds present in the
iii iv
Contents 1.2 Coconut oil quality……………………………… 15
1. Coconut oil………………………………………. 1 1.2.1 Basic quality parameters…………………………. 16

1.1 Extraction of coconut oil………………………... 1 Color……………………………………………… 16

1.1.1 Dry process………………………………………. 1 Acid value………………………………………... 18
Drying coconut kernels…………………………... 2 Peroxide value……………………………………. 21
a) Sun drying……………………………………... 2 Iodine value………………………………………. 26
b) Kiln drying…………………………………….. 4 Saponification value……………………………… 28
c) Hot air drying…………………………………. 5 Anisidine value…………………………………... 30
Desiccated coconut………………………………. 6 Unsaponifiable substances……………………….. 30

1.2.2 Basic quality parameters and the extraction

Preparation of coconut oil by dry process………... 6 method……………………………………………. 31
a) Pressing copra………………………………… 6 Extraction by fermentation and the quality of
coconut oil………………………………………... 34
b) Solvent extraction……………………………... 8
Enzyme assisted extraction and the quality of
c) Extraction of coconut oil by supercritical coconut oil............................................................... 36
carbon dioxide……………………………………. 9
Extraction by supercritical carbon dioxide and the
1.1.2 Wet process………………………………………. 10 quality of coconut oil…………………………….. 38
Boiling coconut milk……………………………... 10 Phenolic substances and the extraction method… 42
Centrifugation process…………………………… 11 1.2.3 Coconut hybrids and the quality of coconut oil….. 45
Fermentation process…………………………...... 13 1.2.4 Polycyclic aromatic hydrocarbons……………….. 46
Enzyme assisted extraction………………………. 13
v vi
1.2.5 Aflatoxin levels…………………………………... 49 4.3 Moisturizers and beauty products……………... 85

4.4 Other chemical applications……………………. 86

2. Saponifiable fraction of coconut oil……………. 51
4.4.1 Oleochemicals……………………………………. 86
2.1 Composition……………………………………... 51
4.4.2 Metal extraction………………………………….. 87
2.1.1 Analysis of fatty acids……………………………. 56

2.1.2 Glycerides in coconut oil………………………… 58 5. Coconut oil and health………………………….. 88

5.1 Antimicrobial activity…………………………... 89

3. Unsaponifiable fraction of coconut oil………… 60
5.2 Antioxidant activity............................................... 90
3.1 Metal content……………………………………. 60
5.3 Coronary heart disease......................................... 95
Organic compounds……………………………… 64
5.4 Alzheimer’s disease……………………………... 102
3.2 Hydrocarbons…………………………………… 64
5.5 Cancer…………………………………………… 104
3.3 Alcohols………………………………………….. 64
References……………………………………….. 106
3.4 Phenolic compounds……………………………. 65
Index……………………………………………... 125
3.4.1 Identification of phenolic compounds……………. 68

3.5 Vitamin E Contents……………………………... 78

4. Industrial uses and other applications of 80

coconut oil……………………………………......

4.1 Lubrication……………………………………… 80

4.2 Biodiesel…………………………………………. 81

vii viii
List of Figures List of Tables
Figure 1 Variation of acid value of coconut oils Table 1 APCC standards for virgin coconut oil……. 17
with time…………………………………... 21
Table 2 Iodine values of edible oils ……………….. 27
Figure 2 Variation of peroxide value of coconut
oil with time……………………………….. 23 Table 3 Average chain length and saponification
values for common edible oils ……………. 29
Figure 3 An -3 fatty acid………………………….. 56
Table 4 Quality parameters of Traditional coconut
Figure 4 GC chromatogram of fatty acid methyl oil (TCO) and copra oil (CO)……………... 34
esters prepared from copra oil…………….. 58
Table 5 Fatty acid compositions of traditional
Figure 5 Effects of Fe3+ (a) and Cr3+ (b) on the coconut oil (TCO) and copra oil (CO)…….. 34
peroxide formation in coconut oil…………. 62
Table 6 Major fatty acids found in coconut oil ……. 54
Figure 6 HPLC chromatogram of the phenolic
fraction of copra oil……………………….. 69 Table 7 Fatty acid composition of coconut oil ……. 55

Figure 7 HPLC chromatogram of the phenolic Table 8 Metal contents in Traditional coconut oil
fraction of virgin coconut oil……………… 70 (TCO) and copra oil (CO)……………….… 61

Figure 8 HPLC chromatogram of the phenolic Table 9 Phenolic compounds in various endosperm
fraction of traditional coconut oil…………. 71 components of coconut …………………… 66

Figure 9 Electrospray ionization mass spectrum Table 10 Total phenolic contents of coconut oils …... 68
of ferulic acid……………………………… 74
Table 11 Comparison of phenolic substances present
Figure 10 The structures of some phenolic substances in traditional coconut oil (TCO) and copra
present in coconut oil……………………… 76 oil (CO) …………………………………… 72

Figure 11 Structure of cholesterol……………………. 98 Table 12 The m/z values for (M-H)- ions generated
by electrospray ionization mass
spectroscopy………………………………. 73

ix x
Table 13 Vitamin E and phytosterol contents of
coconut oils………………………………... 79
List of Schemes
Table 14 Fatty acid composition and quality 89 Scheme 1 Formation of hydroperoxides in
parameters of common cooking oils………. linoleic acid…………………………………. 22

Scheme 2 Triglycerides are derived from the

fatty acids and glycerol……………………… 52

Scheme 3 Mechanism of the antioxidant activity

of an ortho diphenol………………………… 78

Scheme 4 Reduction of molecular weight by

transesterification…………………………... 82

xi xii
 of coconut kernel for the oil extraction by pressing. The dry
1. Coconut oil coconut kernel or copra is prepared from mature coconut
kernel. There are two types of copra, cup copra and ball
Coconut oil is the major choice of fat in Sri Lanka and in copra, which reflect the shape of the copra. Ball copra is
most of the countries in the Asian region. In addition, used for direct consumption in some countries in Asia or it
coconut oil is used in myriad of health and beauty products is used mainly for making sweets. Ball copra is commonly
due to its various health and nutritional benefits. prepared by mildly drying mature coconuts for 8-9 months.
For this, it is not necessary to expose coconuts to direct
sunlight. In this method, coconuts are stored in the shade.
1.1 Extraction of coconut oil The coconut kernel inside the nut shrinks due to slow
evaporation of moisture from the liquid endosperm of
Coconuts have a solid as well as a liquid endosperm. Solid coconut and further drying of the coconut kernel. During
endosperm is the coconut meat known as the coconut this process, the kernel separates from the shell as a ball.
kernel. Coconut oil is derived from the coconut kernel. This detachment of copra ball from the coconut shell can be
Extraction process of coconut oil can be classified into two confirmed by shaking the nut to check for the rattling sound
main types; the dry process and the wet process. Any made by the detached kernel. At this stage, the husk can be
method involving the extraction of coconut oil from dry removed and the shell can be broken to take copra out of
coconut kernel known as copra can be considered as a dry the coconut shell as a ball. In the production of cup copra,
process while the extraction of coconut oil using the coconuts are split-open into two halves and dried using
emulsions of fresh coconut kernel known as coconut milk various methods.
as the starting material is considered as a wet process.
Drying coconut kernels
1.1.1 Dry process
a) Sun drying
Among the dry methods hydraulic press and expeller
process are the major methods of coconut oil extraction in Sun drying is the cheapest and probably the greenest way
commercial scale. Coconut oil prepared by these methods of drying copra. After removing the husk, coconuts are
is commonly called copra oil. In dry extraction, coconut oil halved by breaking the thick shell of the coconut. When
is extracted from dried coconut kernels by pressing or these coconut halves are dried for two days, the low
solvent extraction. The water content in coconut kernels moisture coconut kernels from the halves can be removed
has to be reduced from 50% to about 6% during the drying including the thin brown outer skin of the coconut kernel,

1 2
known as testa. These separated coconut kernel halves are slicing requires a lot of labor and as a result, the cost of
still not suitable for extraction of oil as they contain about production of copra increases. As fungal attacks occur on
30% moisture. The moisture content has to be further the surfaces that are exposed, slicing may promote
reduced to 6% for the copra to be suitable for extraction of deterioration of the kernel if proper sunlight is not
oil. Copra has to be dried in bright sunlight for 8 hours a provided. Therefore, it is safer to split the nuts into halves.
day for at least 7-14 days to lower the moisture content
down to 6%. Though this drying process takes a long time, With the evaporation of water, the oil to water ratio of the
this method is popular among small-scale copra producers, coconut kernel increases. It is easier to extract oil from
as it does not require any special instrument or additional copra, which has low moisture content compared to the
expense for drying. However, the drying process can be extraction of coconut oil from fresh coconut kernel
easily disturbed by rain and cloudy weather. In addition to containing a lot of water. Proper drying of copra to
getting copra wet during rain, the lack of sunlight delays minimize water is important for the production of coconut
the drying process. oil by pressing copra. The water content of the coconut oil
extracted using properly dried copra is negligible. Water
As coconut kernel contains proteins and carbohydrates in content affects the quality of the coconut oil as the presence
addition to the moisture and oil, the kernel is prone to of water in coconut oil promotes the hydrolysis of
fungal attacks, which produce aflatoxins in copra. Fresh triglycerides to give hydrolytic rancidity. In the production
coconut kernel is very susceptible to deterioration, which of desiccated coconut, the drying is done after removing the
results in producing free fatty acids and rancidity due to testa, which gives the light yellowish color to coconut oil.
fungal attacks and other reasons. To minimize fungal In the production of virgin coconut oil, the testa is removed
contaminations, the drying process should be started as and the white coconut kernel is used to produce the
soon as the nut is open. Coconut water (liquid endosperm) colorless oil.
is in contact with white coconut kernel in the nut. As
coconut water is a good source of nutrients, it is a good b) Kiln drying
idea to wash coconut halves before drying to prevent easy
fungal contaminations. However, this may not be possible Coconut kernel can be dried by heating the coconut halves
all the time as it needs additional labor. The drying process in a special kiln or on an open stage as well. In this case,
has to continue without any disruption due to rain or lack of copra is smoked by a fire underneath. This process dries
sunlight in order to prepare good quality sundried copra. In coconut kernel more quickly than the sun drying process.
some instances, coconut kernels or partially dried copra is Kiln drying is important during the rainy season and this
cut into small slices to accelerate the drying process. This drying can also be combined with sun drying. The special

3 4
platform used for this purpose can be set up using bamboo Desiccated coconut
stems or some wood planks. This platform has many empty
or open spaces. Coconut halves are spread on the platform Desiccated coconut is obtained from small particles of
and a fire is made using coconut shells on the floor under coconut kernel by drying ground or shredded coconut
the platform. With slow burning of coconut shells, the kernel after the removal of the brown testa. It is an
coconut kernels on the platform are dried due to the contact important ingredient in confectioneries, puddings and many
of smoke generated by slow burning process underneath. other food preparations. Husk is removed from fresh
The kiln where this platform drying takes place is covered matured coconut. Then the hard shell is removed and
by a brick structure. The temperature of the smoke coconut meat is separated. The testa is removed and the
generated in this drying process is about 40-50 °C and the white coconut kernel is washed with clean water. Then it is
drying time is reduced to 4-5 days due to the hot smoke, grated and sulfur dioxide is passed to obtain a white color.
which is in contact with the copra. Coconut oil produced by The grated coconut kernel mass is blanched with live steam
this copra is inferior in quality and brownish in color. Of for about 20 minutes to bring down the microbial counts.
the different parameters, the width of the drying chamber The blanched mass is then dried in a hot air drier at a
and the distance between the floor where the burning takes temperature of 80-90°C for about 10 hours to bring down
place and the drying platform are critical in the drying the moisture content below 3%. The dried coconut kernel is
process (Rodrigo et al., 1996). Two types of fuels are used tested for moisture, free fatty acids and microbial counts.
in traditional kilns, coconut shells and coconut shell This desiccated coconut kernel contains 2-3% moisture, 65-
charcoal. Better quality copra based on commercial grading 68% fat and 30-32% other solids such as proteins and
system can be obtained by using charcoal as fuel. carbohydrates.

c) Hot air drying Preparation of coconut oil by dry process

This drying process needs fuels other than coconut-based a) Pressing copra
fuels. Therefore, this is a more expensive drying process.
However, the quality of copra produced by this method is The main method of extraction of coconut oil from copra is
superior to kiln dried copra because of the more efficient by pressing copra using expellers. Copra is pressed in large
drying without exposing copra to smoke. The drying time expeller presses that generate heat and pressure. The
of copra by hot air drying is also shorter compared to other resultant crude coconut oil is brown and turbid in
drying methods. Hot air can be generated within the kiln or appearance. This oil can be further purified by filtering and
can be pumped from an outside source. refining to remove free fatty acids (a breakdown product

5 6
from the oil), any remaining moisture, any bad flavor or in the industrial scale production of good quality coconut
smell. Coconut oil made this way is the least expensive of oil. Free fatty acids may also be removed by vacuum
all coconut oils, which is used in food preparations. distillation. Substances responsible for the color of coconut
Pressing is also used to produce virgin coconut oil in the oil can be removed by bleaching agents or passing through
dry extraction process. The quality of copra used in the activated carbon. Removal of unpleasant odors can be
extraction of virgin coconut oil is of high quality and free done by steam-stripping.
of fungal contaminations. Special driers can be used to
prepare copra for this purpose and the brown portion of b) Solvent extraction
copra is not used to prepare virgin coconut oil by pressing
copra. Here, the pressing can be considered as cold A solvent can be used in the extraction of coconut oil from
pressing, since the temperature is controlled. copra. n-Hexane is considered to be the most efficient
solvent for oil extraction as oils easily dissolve in hexane. It
The first step of the oil extraction using a hydraulic press or is the most suitable solvent also because of the low boiling
expellers is the cleaning of copra to get rid of any foreign point, which makes it easier to remove from the oil. It is
matter. Then copra is crushed into fine particles. The also a relatively low cost solvent. However, its
crushed copra is steam-heated to about 100 C for 30 min. flammability, mild toxicity, explosiveness and
This heating process facilitates the expulsion of oil in the environmental impacts are the concerns of industrial scale
hydraulic press process to separate coconut oil. In the solvent extraction of coconut oil. The solvent extraction
expeller process, the heated copra is placed in a rotary leaves low levels of solvent residue in the oil, which is safe
expeller to remove coconut oil. The coconut oil prepared but undesirable for food purposes. During the extraction,
by these methods is subjected to flow through screening the oil in copra is leached out with the solvent and the
tanks and oil is drained out of the foots. Further filtration insoluble copra meal is retained unaffected. The efficiency
may also be carried out to get rid of solid matter from of extraction depends upon the temperature of the solvent,
coconut oil. The crude oil prepared by these methods can the ratio of the solvent to copra meal, size and the porosity
be further refined by various stages. However, the refining of the copra particles and contact time with the solvent. Oil
and modification are not essential for the edible purposes extraction by solvent extraction is more suitable for oil
and the gum contents in coconut oil are much less seeds containing relatively low amounts of oil. As copra
compared to other vegetable or seed oils. Removal of free contains about 70% oil, mechanical extraction by pressing
fatty acids and gums can be done by using weak alkali is more efficient and economical. In addition to the full
solutions. Here, free fatty acids are removed as soaps. solvent extraction, prepress solvent extraction can also be
However, alkali process is not commonly used these days used. In the mechanical extraction by pressing under

7 8
moderate pressure, the oil content of copra can be reduced SC-CO2 extraction of soybean oil has been studied and the
to nearly 15%. This remaining oil can be further extracted equilibrium solubility data for different temperatures and
by solvent extraction. The resultant mixture of solvent pressures have been reported. The operating costs for SC-
extraction includes oil, solvent solution and extracted CO2 and solvent extraction of soybean oil has been studied
coconut meal. The solvent in the meal is removed by and compared (Reverchon & Osseo, 1994). Though the
heating to boil off the volatile solvent and the solvent is initial costs of the establishment of SC-CO2 system is
recovered by condensation. The remaining solvent in the higher, the operational costs fell in the same range as
oil solution is removed by distillation. Traces of solvent left conventional hexane extraction plants.
in the meal and the oil are removed by steam-stripping
under reduced pressure. Various high temperature steps in Triglycerides in seed oils are readily soluble in SC-CO2 at
the solvent extraction process may thermally degrade the 40°C and at pressures higher than 280 bar. The main
oil to a very small extent and about 500-1000 ppm parameters important for efficient oil extraction in this
concentrations of solvent will also remain in the oil after method are particle size, pressure and residence time. Small
purification. particles of about 1mm mean diameter or less and high
pressures (300–500 bar) can strongly reduce the extraction
c) Extraction of coconut oil by supercritical carbon time. After extraction, the SC-CO2 triglycerides solution is
dioxide sent to a separator working at subcritical conditions. This
operation reduces the solvent power of CO2 and allows the
Extraction of seed oils by supercritical carbon dioxide (SC- recovery of oil. The complete elimination of gaseous CO2
CO2) can overcome the problem of solvent residues present from oil is also accomplished in this step. The SC-CO2
in oils extracted by solvent extraction. Different extraction of seed oils has been tested up to pilot scale for
compounds in seed kernels may be incorporated into seed several seed oils.
oils by changing pressure and temperature of carbon
dioxide. However, the establishment of a supercritical 1.1.2 Wet process
extraction unit needs high investment. Thus, the technology
is not in widespread use, though the quality of oil extracted Boiling coconut milk
by this method is claimed to be high. Information about the
operational costs of this method of extraction based on Among the wet methods where fresh coconut meat is used
systematic studies is not available for coconut oil and for oil extraction, boiling of coconut milk to separate
several other vegetable oils. Coconut oil has not been coconut oil has been the major domestic process of coconut
produced in commercial scale by SC-CO2 extraction. The oil extraction in Sri Lanka until recently. In this process,

9 10
coconut kernel is scraped and hand pressed with water to other types of coconut oil is the use of lower temperatures
obtain coconut milk. This coconut milk emulsion is heated in the process of oil extraction. The major method of the
until water is evaporated and the remaining oil is separated. extraction of virgin coconut oil involves the centrifugation
The oil can also be separated from the water while the process.
coconut milk is still boiling. Heating breaks down and
deposits proteins at the bottom of the container. When the In this method, fresh coconut kernel is chopped and pressed
heating is continued, water in the emulsion evaporates. Due by an expeller. The coconut milk emulsion prepared by
to its high boiling temperature, coconut oil does not pressing fresh coconut kernels contains approximately 40%
evaporate significantly during this process. Finally, the oil. In the production of high quality virgin coconut oil, the
coconut oil can be separated by decanting from the residue pressing should be done using a special machine of which
containing proteins, carbohydrates and other substances. both the pressing plate and the sleeve are cooled by chilled
The resultant coconut oil gives a nice coconut aroma and water. The temperature of the extracted coconut milk
the oil is free of water. This oil can be kept for a very long emulsion is maintained below 25 C. Using a centrifuge,
time without forming oxidation products that cause the cream is then concentrated to yield a higher percentage
rancidity. However, due to caramelization and other of oil while the proteins and water-soluble substances are
reactions, the coconut oil produced by this method has a separated out. Coconut oil produced by this method has a
color. One disadvantage of this method is the high amount very light coconut flavor and the texture of coconut oil is
of energy needed and relatively longer period of time taken extremely mild and smooth. In some instances, coconut
to evaporate water from the coconut milk emulsion. In milk is chilled at 10C for 10 h to solidify the lipids. Then
addition, there are no machines designed to produce the aqueous layer is discarded and the lipid block is
coconut oil in industrial scale using this method. Therefore, allowed to stand at 30C until it dissolves completely. Then
this method is limited to the preparation of coconut oil in the mixture is centrifuged and the oil layer is separated. In
small scale for household consumption. The coconut oil the traditional Philippines method of virgin coconut oil
produced by this method is referred to as traditional extraction, coconut milk emulsion is allowed to stand for
coconut oil (TCO) in this book. 12-17 h. During this time, the natural enzymes break down
the proteins that hold the oil in solution. Then the oil can
Centrifugation process be separated. The coconut oil produced by this
centrifugation method is considered to be one of the highest
The preparation of virgin coconut oil involves the wet and quality coconut oils. These oils are expensive and usually
cold extraction of coconut oil. The major difference labeled as extra virgin coconut oil.
between the extraction of virgin oil and the extraction of

11 12
Fermentation process kernel is mixed with water and the mixture is treated with
enzymes. The released oil can be separated by
Fermentation method is the least consistent of all the centrifugation. A reported enzymatic treatment includes the
coconut oil production processes. Therefore, the quality of boiling of milled copra with water followed by cooling and
coconut oil produced by this method varies for different enzymatic treatment (Debrah & Ohta, 1997). The yield of
producers. The oil has to be further purified for food coconut oil increased from 42 % in the traditional
purposes. In the preparation of coconut oil by this method, extraction from copra to 65 % by treatment of milled copra
fresh coconut kernel is first grated and then coconut milk or in water with a mixture of protease, hemicellulase and
cream is pressed out from the white flesh. This milk is cellulase. Even though enzymatic treatment is used in this
placed into vats or buckets and allowed to ferment at about method, the oil separation was done by making an emulsion
37C. The enzymes and bacteria break the proteins in of oil in hot water and evaporation of water by boiling the
emulsion and separate the milk into different layers which mixture. The presence of enzymes facilitates oil recovery
include a top protein curd layer, a coconut oil layer by breaking cell walls and oil bodies. The oil recovery can
underneath, another curd layer and a layer of water. The vary from 80-98%. A single enzyme is not sufficient to
protein curd on the top can be removed and then the oil break the insoluble cell wall materials to release oil
layer can be siphoned. (Rosenthal et al., 1996).

Enzyme assisted extraction The polysaccharides of fresh mature coconut kernels are
galactomannans (61%), mannans (26%) and cellulose
Usually the oils in plants are found inside the vegetative (13%) (Balasubramanium, 1996). When an aqueous
cells linked with other macromolecules such as proteins medium of ground desiccated coconut kernel was treated at
and carbohydrates. Therefore, hydrolysis of the 50C with a mixture of commercially available enzymes
macromolecules facilitates the oil extraction process. High including a hemicellulase preparation, a pectinase
yield of good quality coconut oil can be produced by using preparation, a cellulase preparation and an enzyme complex
enzymes to hydrolyze cellular material in coconut kernel with multiple activities, 84% of the coconut oil present in
(McGlone et al., 1986). The enzymes can be crude mixtures coconut kernel was released (Chen & Diosady, 2003). The
of protease, cellulase, hemicellulase and amylase enzymes. incubation followed by centrifugation gave a clear oil
Enzyme assisted extraction of edible oils is an eco-friendly phase, an emulsion layer, an aqueous phase, and a solid
process based on isolation of coconut oil and proteins in an phase containing the remaining coconut meal. Proteins of
emulsion. Copra meal prepared by cutting copra and the solid residue was extracted by freeze drying the solid
passing through a 1 mm mesh or grated fresh coconut and treating with aqueous alkali, which dissolved 88% of

13 14
the proteins in the solid phase. The acidification of the commercially attractive parameters because these values
protein solution towards the isoelectric region precipitated are directly connected to the rancidity of oil. Iodine value
93.5% of dissolved proteins. Therefore, enzymatic and saponification value are important in checking the
extraction has an additional advantage because of the authenticity of an oil. The most crucial parameters
recovery of proteins. important for the nutritional quality are the identity of fatty
acids in the triglycerides of the oil and the non-lipid
The commercial importance of the enzyme assisted components.
extraction of coconut oil depends on the price and
efficiency of enzymes. In addition, the cost for separation 1.2.1 Basic quality parameters
of oil has to be taken into account. There is no commercial
scale extraction of coconut oil by this method in Sri Lanka. Various quality parameters have been proposed in order to
establish the quality of coconut oil. Asian Pacific Coconut
1.2 Coconut oil quality Community (APCC) and Codex Alimentarius have
established the values of quality control parameters in
Coconut oil is a stable oil due to its high saturated fatty acid physical, chemical and microbiological aspects of coconut
content. Due to this thermal stability, coconut oil is oil. Quality parameters established by Codex Alimentarius
considered probably the most suitable oil for frying for coconut oil are acid value or free fatty acid percentage
purposes. The progress of lipid oxidation of coconut oil (none), peroxide value (<15 meq/kg oil), iodine value (6.3-
was assessed by measuring peroxide value, anisidine value 10.6) and volatile matter percentage at 105C (0.2%).
and total oxidation value during a period of 12 months. The APCC standards of quality parameters for virgin coconut
low peroxide value (0.24–0.49 meq/kg oil) signifies a high oil are given in the Table 1.
oxidative stability, while anisidine values were in the range
0.19-0.87. Fourier transform infrared (FTIR) spectroscopy Color
was used to monitor the peak changes due to oxidation
during storage. The results of this study suggest that Usually, coconut oils extracted by many extraction methods
coconut oil retains its good chemical properties during 12 have a light yellow color. Colorless coconut oil is
months of storage (Moigradean et al., 2012). When the considered as commercially more acceptable good quality
quality of coconut oil is evaluated, it is important to coconut oil. Due to this reason, refined, bleached and
consider both nutritional quality and commercial quality. deodorized (RBD) coconut oil is prepared. One source of
Acid value, peroxide value and anisidine value are the light yellow or light brown color of coconut oil is
coconut testa. When processing copra, some colored

15 16
substances get incorporated into coconut oil. If copra sugars present in coconut milk or due to various oxidation
without coconut testa is used for the dry extraction of reactions of the non-lipid substances. Even though the color
coconut oil, the color of coconut oil will be colorless. In of coconut oil is important as a commercial parameter, the
both dry and wet extraction of virgin coconut oil, this color does not reflect the nutritional quality of coconut oil.
brown thin skin of coconut kernel is avoided. As a result,
the extracted virgin coconut oil is colorless. Acid value

Table 1. APCC standards for virgin coconut oil Triglycerides of coconut oil and other vegetable oils
undergo hydrolysis to produce free fatty acids. Acid value
Parameter Maximum value of an oil is a measure of the amount of free acids present in
or range the oil. The major component of oil is the triglyceride
Moisture (%) 0.1 portion. These triglycerides produce free fatty acids upon
Volatile matter, 120 C (%) 0.2 hydrolysis which can occur due to the action of lipase
Free fatty acid (%) 0.2 enzyme. The source of enzyme can be from the broken
Peroxide value, meq/kg 3 cells or tissues during the extraction process of coconut oil
Density, g/ml 0.915-0.920 or from microorganisms. Freshly extracted coconut oil has
a low acidity. The acidity is an indicator of aging oil. The
Refractive index, 40 C 1.4480-1.4492
free acid formation due to hydrolysis of oil can accelerate
Insoluble impurities (%) 0.05
due to poor extraction and storing conditions of coconut oil.
Saponification value, mg 250-260 Acid value is defined as the weight of potassium hydroxide
KOH/g oil (KOH) in mg needed for the neutralization of free fatty
Iodine value 4.1-11 acids from 1 g of the oil. This means that bound fatty acids
Unsaponifiable matter (%) 0.2-0.5 in triglycerides are not counted for acid value calculations.
Total plate count 0.5 The acid value of coconut oil can be determined by titrating
Color Colorless a sample of coconut oil dissolved in ethanol: diethyl ether
(APCC, 2009) (1:1 v/v) with a standard solution of KOH using
phenolphthalein indicator. Even though the acid value unit,
Coconut oil can be extracted by heating coconut milk
mg KOH/g oil is frequently used by chemists, the acidity is
emulsion during wet extraction. In this case, light yellow or
also expressed as a percentage by weight of total fat. Here,
light brown colored coconut oil is resulted and this color is
the number of moles of free acids found by the titration can
due to caramelization of non-lipid substances such as
be converted to mass by multiplying the moles by the

17 18
molecular weight of fatty acids. As it is a fatty acid Free fatty acid contents of coconut oil prepared by wet
mixture, the molecular weight of the major fatty acid of the methods are usually much lower than those of coconut oil
oil is usually considered for the calculation. In coconut oil, prepared by dry methods. The free fatty acid content or
free fatty acid content is given as lauric acid equivalents acid value given by the producers of virgin coconut oil is
while in olive oil it is given as oleic acid equivalents. When about 0.02 % as lauric acid. The acid value of coconut oil
the acid value percentages are given as the major fatty acids extracted by boiling coconut milk (traditional coconut oil,
in different oils, such acid values for different oils cannot TCO) is significantly lower than that of commercial
be easily compared. Therefore, the acid value expressed as coconut oil prepared by pressing copra (copra oil, CO)
mg KOH/g oil is always easier for comparison purposes. (0.31  0.10 vs 2.51  0.34 mg KOH/1g oil: P = 0.0036)
(Seneviratne et al., 2002). Even when coconut oil is
As triglycerides get hydrolyzed to form free acids, glycerol prepared freshly from copra, the acid value of such oil is
is also formed. The acid value of an oil changes with time higher than that in coconut oil prepared by boiling coconut
because of the hydrolysis of triglycerides. Therefore, the milk. Reasonable acidity of freshly prepared copra oil may
acid value is an indication of the aging of oils. Free fatty be due to formation of small amounts of free fatty acids
acids in oils are more easily oxidized compared to the fatty during the copra drying process. Coconut oil samples
acids in ester form in triglycerides. The rancidity of the oil collected freshly from the large scale mills where copra is
is caused by the free fatty acids and the relatively more stored longer times showed even higher acidity (3.20 
volatile oxidized substances of free fatty acids. The free 0.45 mg KOH/1 g oil) indicating that the formation of free
fatty acid content or acid value of coconut oil increases acids is possible during the storage of copra. Variation of
with the storage time. Due to volatility of free short chain the acid value with time in TCO and CO is given in Figure
fatty acids, a light rancid smell may be observed. Free fatty 1. The rate of free acid formation was found to be about
acids and glycerol also change the taste of the oil or oil three times faster in CO compared to that of TCO.
based food. Rancidity due to the free fatty acids and
glycerol formed by hydrolysis of triglycerides is called
hydrolytic rancidity. This rancidity is milder than the
rancidity resulting from the aldehydes and ketones due to
oxidation of fatty acids. Therefore, hydrolytic rancidity
arising mainly from free fatty acids is not seriously
objectionable to the consumers as to cause serious
economic disadvantageous.

19 20
 the presence of a small amount of unsaturated fatty acids
compared to most other vegetable oils.

There are several methods to determine the peroxide value

of coconut oil. Among those methods, thiocyanate assay
method (Mitsuda et al., 1966) is an easy method that can be
used in any laboratory. The basis of this method is the
measurement of the ability of formed peroxide to oxidize a
substrate.

COOH

1
O2 (Singlet oxygen)
Figure 1. Variation of acid value of coconut oils with time
OOH
Peroxide value
COOH
Lipid peroxidation causes rancidity in oils and fats. Fatty
Linoleic acid hydroperoxide
acids with double bonds are more susceptible to lipid
peroxidation because allylic positions (carbons next to
double-bonded carbon) of the fatty acid carbon chains are Scheme 1. Formation of hydroperoxides in linoleic acid
more reactive towards oxygen to form peroxides. The
formation of peroxides in linoleic acid is shown in Scheme
In the thiocyanate assay method, the amount of peroxide
1.
formed in an oil is determined by the oxidation of Fe2+ to
Fe3+ by peroxides. The amount of Fe3+ can be determined
Subsequent decomposition of the hydro peroxide forms
by the intensity of the red color of the ferric thiocyanate
several oxidized products with unpleasant odors and
complexes. An ethanolic solution of coconut oil is reacted
flavors. Coconut oil is a relatively more stable oil due to
with FeCl2 in HCl and NH4SCN is added to the mixture.
The absorbance is measured at 500 nm using a

21 22
spectrometer with respect to a blank with no added coconut Other methods of evaluating oxidative stability
oil. The peroxide value can be expressed as the absorbance
at 500 nm. The variation of peroxide value of TCO and In the conjugated diene hydroperoxide (CDHP) method
CO with time, measured by the thiocyanate assay method is (Yoon et al., 1985), the conjugated diene and triene
shown in the Figure 2. contents of oil are determined spectrophotometrically at
232 nm and 268 nm respectively. For the measurements,
oil samples are diluted in iso-octane to a final concentration
of 2 mg/10 mL. When the methylene hydrogens are
abstracted to form radicals in polyunsaturated oils, the
double bonds can rearrange to form conjugated double
bonds. Conjugated systems show stronger UV absorptions
than do non conjugated systems. CDHP method is not a
very effective method for monitoring peroxides in coconut
oil due to the relatively low polyunsaturated fatty acid
content in coconut oil.

In the thiobarbituric acid (TBA) test, the oxidized oil is

reacted with TBA. Malondialdehyde (MDA) is a
decomposition product of the hydroperoxides formed in
Figure 2. Variation of peroxide value of coconut oil with oils as a result of oxidation. This MDA reacts with TBA to
time give a pink-colored complex which absorbs at 450nm, 530
nm or 538 nm. This method measures the secondary
In addition to the thiocyanate method, other methods are oxidation products resulting from the oxidation of primary
also used to estimate the peroxide formation. For example, oxidation products such as peroxides.
the oil sample in chloroform can be reacted with saturated
KI which is oxidized to I2 by peroxides. The released I2 The oxidative stability or peroxide formation of oils can
makes a blue color with starch indicator and the intensity of also be monitored thermogravimetrically. When the
the color can be measured at 563 nm with respect to a blank peroxides are formed, the weight of an oil sample
with no added oil. increases. TBA method and thermogravimetric methods
are also more suitable for oils containing high percentage
of polyunsaturated fatty acids. MDA is formed more

23 24
effectively in oils containing high percentage of The traditional coconut oil, prepared by prolonged boiling
polyunsaturated fatty acids. Because of the low of coconut milk also has low peroxide values. The peroxide
polyunsaturated fatty acid content, coconut oil does not value of copra oil is about 20 times higher than that of
give good results by these methods. Because of the slow traditional coconut oil. The rate of peroxide formation in
formation of peroxides in coconut oil due to its low commercial coconut oil was found to be about four times
polyunsaturated fatty acid content, thermogravimetric faster in copra oil compared with that of traditional coconut
methods give inconsistent results. oil. Peroxide value of coconut oil varies with processing
time, storage time of copra and storage time of coconut oil.
Peroxides are primary oxidation products of coconut oil Usually, coconut oil prepared by wet methods contains
formed due to free radical reactions and these peroxides smaller amounts of peroxides compared with coconut oil
further break into shorter chain secondary oxidation prepared by dry methods. For example, the peroxide value
products such as aldehydes and ketones that are volatile, of freshly prepared virgin coconut oil is almost zero while
giving the smell of rancidity, which is known as oxidative that of traditional coconut oil is 0.03 absorption units.
rancidity. Therefore, the peroxide value may increase in the However, peroxide values up to 0.60 absorption units have
beginning and then secondary oxidation products appear been noticed in our studies for some samples of copra oil
later. Virgin coconut oil has a lower peroxide value (Seneviratne & Dissanayake, 2005).
compared to copra oil, which indicates the freshness of
virgin coconut oil. Recommended maximum value for High content of saturated fatty acids of coconut oil gives a
peroxides in coconut oil is 3 meq/kg. Copra oil, even after high oxidative stability to coconut oil. Therefore, peroxide
freshly collected from a mill has a peroxide value higher formation is minimum in coconut oil prepared by any
than that of virgin coconut oil prepared by dry or wet method of extraction compared to other polyunsaturated
methods. This indicates that longer drying period of copra oils. Then coconut oil can be considered as the most stable
may also contribute to the formation of peroxides as and, therefore, most suitable oil for deep-frying.
mentioned earlier. Peroxide formation is also catalyzed by
the presence of metal impurities. Pressing and grinding of Iodine value
copra and storing coconut oil in metal barrels may
introduce dissolved metals such as iron into coconut oil. The number of grams of iodine required to saturate 100 g
This dissolving of metals is supported by the acidity of of oil is defined as iodine value or iodine number. Iodine
coconut oil if the acid value of coconut oil is high. value reflects the degree of unsaturation of the fatty acids
of oils. Since I2 reacts with the double bonds of fatty acids,
a high iodine value indicates a high degree of unsaturation

25 26
in oils. In the determination of the iodine number, coconut This parameter does not change significantly with the
oil is mixed with an ICl solution in a glass stoppered bottle. method of extraction if same quality coconut kernel is used
The mixture is shaken thoroughly and kept in the dark for for the extraction of coconut oil. However, low quality
30 min. A solution of KI is added and the liberated I2 is coconut oil for nonfood purposes can be obtained by
titrated with a standardized solution of Na2S2O3 using pressing coconut pairings and this oil is called pairing oil.
starch as the indicator. Due to the low unsaturated fatty Such pairing oil may have slightly higher iodine values
acid content in coconut oil, compared with other vegetable compared to other coconut oils. However, quality of pairing
oils, the iodine number of coconut oil is lower. The oil is low not because of the slightly different iodine value
percentages of double bonds and the iodine values of but due to higher peroxide value and higher acidity.
common edible oils are given in Table 2.
Saponification value
Table 2. Iodine values of edible oils
Saponification value is defined as the number of milligrams
of potassium hydroxide (KOH) required to neutralize the
Type of oil Double bond %a Iodine value
free fatty acids and the bound fatty acids in triglycerides
Canola ~114 110-120 resulting from the complete hydrolysis of one gram of oil.
Saponification value is an indication of the molecular
Coconut ~12 6-11 weight distribution of fatty acids present in the lipids. This
Corn ~142 102-130 value is inversely proportional to the mean molecular
weight of the fatty acids in oil. Saponification value reflects
Olive ~83 79-88 the number of fatty acid units in a given weight of oil.
Peanut ~105 84-100 When the molecular weights of the fatty acids are lower,
there will be more fatty acid molecules in one gram of oil
Sunflower ~153 110-143 to react with KOH. If the fatty acids present in an oil are
Sesame ~132 103-116 relatively small, the saponification value is relatively high
as more units of fatty acids are present in a given weight
Soy bean ~97 120-143 that is going to be saponified by KOH. This means that if
a
Assuming that maximum percentage of double bonds (300 %) is the average molecular weight of the oil is low, the
given by an oil containing triglycerides with 100 % of linolenic saponification value is high. Fatty acid compositions of all
acid. common edible oils are well known. Therefore, average
molecular weight, which reflects the average chain length

27 28
of fatty acids can easily be calculated. When the average to the presence of this unique composition of shorter and
chain length of the fatty acids present in triglycerides of an medium chain fatty acids, coconut oil has a higher
oil is shorter, the saponification value becomes higher. saponification value and this value in coconut oil is the
Table 3 shows this relation between saponification value highest among almost all other edible oils. Saponification
and average chain length of fatty acids of four common value also does not change significantly with the method of
edible oils. When comparing reported saponification values extraction of coconut oil. However, slightly high
for different oils or fats, it is important to check the units saponification values may be observed for oils with other
and the base used for saponification. The saponification non-lipid substances, which may react with potassium
values are given as milligrams of KOH per gram of oil, hydroxide.
milligrams of NaOH per gram of oil, grams of KOH per
gram of oil or grams of NaOH per gram of oil. Anisidine value

Table 3. Average chain length and saponification values Peroxide value is used to analyze primary oxidation
for common edible oils products. It is important to evaluate the oxidative status of
oils by both primary oxidation products as well as
Carbon chain length Saponification secondary oxidation products. If an oil initially has a high
of fatty acid value (mg peroxide value, keeping the oil in stock for a long time in
Type of oil C6– C16- Above KOH/g oil) absence of oxygen, produces secondary oxidation products
C14 C18 C18 that determine the decrease of peroxide value but the
Canola - 100 186 - 198 increase of anisidine value. Over time, these peroxides get
Coconut ~80 ~20 - 250 – 268 further oxidized to volatile compounds such as hexanal and
Corn ~1 ~98 ~1 187 – 193 other non-volatile aldehydes and ketones. Anisidine values
Olive ~1 ~99 - 190 – 195 reflect the amount of relatively non-volatile aldehydes and
Peanut - ~91 ~9 185 – 195 ketones.
Sunflower ~1 ~96 ~3 188 – 194
Sesame - ~98 ~2 188 – 195 Unsaponifiable substances
Soy bean - ~98 ~2 180 - 200
Even if all the insoluble impurities are removed from
Coconut oil has a unique fatty acid composition of short coconut oil, the oil still has up to about 0.5 % of
and medium chain fatty acids as indicated in Table 3. Due unsaponifiable matter, which include polyphenols,
alcohols, terpenoids, and several other organic substances

29 30
(Kirschner & Harris, 1961). Quality parameters of coconut such as color, acid value, peroxide value, iodine number,
oil are mainly and traditionally defined for the lipid saponification value and anisidine value, etc. These
fraction. However, many studies conducted in recent times parameters change over a range of values not only because
show that unsaponifiable components are also important to of the method of extraction but also because of cultivar and
evaluate the quality of oil. maturity of coconut. Most of the records in literature give
the values for copra oil and virgin coconut oil. Copra oil
The quality parameters of traditional coconut oil (TCO) and refers to the coconut oil extracted by dry process by
commercial coconut oil prepared by pressing copra (CO) pressing sun dried or kiln-dried copra. Virgin coconut oil
are summarized in Table 4. Table 5 shows that there is no has been made either dry process or wet process. Careful
significant difference in the fatty acid composition in observation of the reported data indicates that the quality
traditional coconut oil and copra oil. However, the parameters such as iodine value and saponification value do
saponification values of the two types of coconut oil are not change significantly in coconut oils extracted by any
significantly different. One important factor other than the method. However, acid value and peroxide value can vary
fatty acid content that may contribute to the higher significantly in oils extracted by different methods and also
saponification value of traditional coconut oil is the with the aging of oils. Wet extracted coconut oil by
presence of higher amounts of other acidic compounds in centrifugation or enzymatic degradation contains lower free
the unsaponifiable fraction of coconut oil. These acidic fatty acid content and peroxide value. Coconut oil extracted
compounds can react with KOH to give a higher by dry methods or copra oil has a relatively higher acidity
saponification value. Traditional coconut oil has lower and peroxide value. However, for the extraction of virgin
peroxide values and acid values. The peroxide value and coconut oil by dry method, high quality copra prepared by
the acid value of oils increase with ‘aging’ of the oil. As quick drying in better conditions is used. Therefore, acid
explained above, Traditional coconut oil is prepared freshly values of such coconut oil are lower compared to normal
from coconut milk and the acid value and peroxide value commercial coconut oil.
are lower due to this reason.
Among drying methods of copra, hot air drying is used to
1.2.2 Basic quality parameters and the extraction produce high quality copra in a relatively shorter period of
method time compared to other drying methods. Studies have been
conducted to assess the quality of copra and coconut oil
How extraction method affects the quality of coconut oil is prepared using copra, dried in laboratory scale hot air driers
reviewed by the authors in the book by Apetrei (2015). (Guarte et al., 1996). In a laboratory scale drier, at a
Quality of coconut oil is evaluated by basic parameters constant air velocity of 0.5 m/s, the moisture reduction rate

31 32
of copra (down to 7%) increases with the drying Table 4. Quality parameters of traditional coconut oil
temperature from 40-90C. At this temperature range, the (TCO) and copra oil (CO)
quality of copra or coconut oil was not affected. At
temperatures above 90C browning of copra occur due to Source Acid Saponification Iodine Peroxide
Maillard reaction. However, drying temperature up to value value (mg of value (g value
100C does not affect the oil content, acid value, anisidine (mg of KOH/g) of (absorbance
KOH/g) I2/100 at 500 nm)
value or saponification value. Drying copra at 90C in a hot g)
air dryer can reduce the moisture down to 7% within one TCO 0.40  274  2a 6.6  0.034 
day without making any changes of color, smell or taste of 0.02a 0.2a 0.002a
copra. Drying under this condition does not affect the CO 3.5  241  3b 6.2  0.62 
contents of fatty acids such as lauric and palmitic. Other 0.9 b
0.3a 0.04b
fatty acids showed small differences with no definite trend Each data point represents the mean of eight replicates  S.E
in variation with the temperature. Coconut oil prepared by (standard error); Different superscript letters in a same column
dry and wet methods have been compared for copra oil denote a significant difference (p<0.05) by MINITAB 2-sample t
prepared by pressing dry copra in a small scale expeller and test (Seneviratne & Dissanayake, 2005)
for coconut oil prepared by prolonged boiling of an
emulsion of coconut milk in the traditional method Table 5. Fatty acid compositions of traditional coconut oil
(Seneviratne & Dissanayake, 2005). The quality parameters (TCO) and copra oil (CO)
are given in the Table 4 and fatty acid compositions are
given in the Table 5. According to this study, acid value, Fatty acid
peroxide value and saponification value of the two types of Source 6:0 8:0 10:0 12:0 14:0 16:0 18:0 18:1 18:2
oils are significantly different and the iodine values showed TCO 0.63 9.2 6.5 49.6 19.2 7.2 2.4 4.5 1.1
0.04 0.1 0.1 0.2 0.1 0.1 0.1 0.1 0.1
no significant difference. Fatty acid compositions of the
CO 0.53 8.6 6.4 48.7 18.9 7.6 2.4 4.9 1.3
two types of oils were not significantly different enough to 0.04 0.1 0.2 0.2 0.1 0.2 0.1 0.2 0.1
cause any nutritional changes.
Each data point represents the mean of three replicates  S.E.
(Seneviratne & Dissanayake, 2005)

33 34
Extraction by fermentation and the quality of coconut specific gravity, refractive index, insoluble impurities, free
oil fatty acid content, peroxide value, iodine value,
saponification value, unsaponifiable matter, and fatty acid
In wet processing, natural fermentation carried out by compositions of virgin coconut oil produced by natural
microbes present in the natural environment is well known fermentation and induced fermentation were within the
for its traditional and industrial applications. In this limits of APCC standards. However, the moisture content
process, the fermentation of coconut oil is usually carried of virgin coconut oil by natural fermentation (0.52%) and
out without applying any heat. This natural fermentation induced fermentation (0.56%) is little higher than the
process has contamination problems due to the presence of APCC values (0.1- 0.5%). Total aerobic plate count of
unwanted microorganisms and uncontrolled conditions. It virgin coconut oil by natural fermentation was 31 colony
leads to the production of poor quality coconut oil, usually forming units (CFU) per 0.1 mg while that of virgin
yellow in color, with a rancid smell. Therefore, induced coconut oil by induced fermentation was 49 CFU/0.1 mg.
fermentation method, using certain species of probiotic Both oils contained about 6 mg/100 g tocopherols. The
microorganisms, can be used under semi-controlled impurities and free acids of the coconut oil prepared by
conditions. Quality parameters for virgin coconut oil fermentation process can be removed to some extent by
produced both by natural fermentation and induced diatomaceous filters and carbon filters. As the moisture
fermentation under semi-controlled conditions have been content of this coconut oil is high, the oil has to be heated
studied and compared with the quality standards given by for several hours at 100 C to remove water. Due to the
APCC (Neela & Prasad, 2012). In this experiment, coconut presence of moisture, free fatty acids and a high peroxide
milk was allowed to ferment naturally in a laboratory scale value, coconut oil produced by fermentation is of poor
experiment in a separating funnel or in a clean container quality.
and the mixture was allowed to stand for 48 hours at room
temperature. During the production of virgin coconut oil by Enzyme assisted extraction and the quality of coconut
natural fermentation, contaminations by different microbes oil
occurred, resulting in yellow-colored, spoiled, coconut oil.
The fermentation was also carried out under controlled In the wet extraction of coconut oil from a coconut milk
conditions. Here, coconut milk was sterilized and a pure emulsion, the most difficult part is the separation of oil
culture of L. plantarum was used in fermentation. The yield from the proteins and cell wall matter. The yield of coconut
of virgin coconut oil from the natural fermentation was oil prepared by wet extractions is usually less unless
25.68± 0.96% while that of induced fermentation was modifications are done to the extraction method. In a wet
28.47±1.07%. Physico-chemical parameters such as extraction method, conditions for destabilization of coconut

35 36
milk emulsion have been studied by employing different extraction. The enzyme was added 1% rate of the copra and
treatments such as thermal, pH, enzyme, chilling and allowed to stand for 30 min. After enzyme treatment, the
combination of enzymes and chilling treatments meal was extracted by hot water and the emulsion was
(Raghavendra & Raghavarao, 2010). The coconut milk boiled to evaporate water. This enzyme pretreatment of
emulsion was treated with protease enzyme at 0.1% copra prior to the extraction improved the yield of coconut
concentration and incubated at 25C and 37C for 2 h. Out oil by 50% compared to the same extraction procedure
of these treatment methods, the most effective method for without enzyme pretreatment. However, the quality of oil
destabilization of coconut milk emulsion was found to be extracted by enzyme pretreatment method was similar to
combination treatments, which gave a high yield of 94.5% the oil extracted without enzyme pretreatment (Debrah &
oil. The oil obtained by combination of treatments Ohta, 1997).
contained lower free fatty acids and peroxides and higher
lauric acid content compared to commercial coconut oil. Extraction by supercritical carbon dioxide and the
quality of coconut oil
In addition to the separation of coconut oil from a coconut
milk emulsion, enzyme treatment can also be used to Extraction of coconut oil by supercritical carbon dioxide
extract coconut oil from finely divided copra meal. (SC-CO2) extraction has been reported by several authors.
Coconut oil extraction based on the enzymatic action of CO2 is a nonpolar solvent at supercritical conditions and
polygalacturonases, α-amylase and proteases on a diluted triglycerides in coconut oil are easily soluble in CO2. The
coconut paste has been tested (McGlone et al., 1986). After main parameters to be taken into account when coconut oil
the reaction with enzymes, the mixture gave three phases is extracted by SC-CO2 extraction are particle size, pressure
after centrifugation. The upper phase contained high quality and residence time (Reverchon & De Marco, 2006). Small
coconut oil and the middle layer and the lower layer particles and high pressures can strongly reduce the
contained water and coconut meal respectively. This extraction time. After extraction, the SC-CO2-tryglicerides
process gave a yield of 80%, which is a much higher yield solution is sent to a separator working at subcritical
compared to other traditional wet extraction methods. conditions. The complete elimination of gaseous CO2 from
Enzyme assisted extractions have also been used to extract oil is obtained in the separator.
coconut oil from powdered copra. The crude commercial
enzyme used in this study contained -amylase, neutral In a study, coconut kernel has been dried by a microwave-
protease, acid protease, cellulase/hemicellulase, and assisted method and the resultant dried kernel material has
pectinase. The enzyme treatment in this process can be been used to extract oil by supercritical extraction (Quitain
considered as a pretreatment of copra prior to the oil et al., 2003). The sample of grated coconut kernel was

37 38
dried using microwave-assisted low-temperature air-drying quality parameters such as free fatty acid content and
method. The microwave frequency used in the drier is 2.45 peroxide value, 31P NMR spectroscopy and head space
GHz and this is similar to the frequency of domestic solid phase microextraction gas chromatography coupled to
microwave ovens. The typical operating temperature was mass spectroscopy (SPME/GCMS) (Dayrit et al., 2011).
set at 40 °C. About 95% of oil recovery can be achieved Virgin coconut oil has higher free fatty acids, moisture and
within 20 h using this method while the cold press method volatile matter and lower peroxide value. 31P NMR analysis
of virgin coconut oil extraction gives a recovery of about has shown that virgin coconut oil and RBD coconut oil can
50%. Therefore, the supercritical extraction method seems be distinguished by total amount of diglycerides. Virgin
to be more efficient than the cold press method. However, coconut oil contained 1.55 w/w% and RBD coconut oil
the economic aspects of the two methods have not been contained 4.10 w/w% diglycerides. Virgin coconut oils
compared. In the supercritical extraction method, the prepared by different methods such as expeller process,
drying method, whether it is microwave assisted, hot air or centrifugation process and fermentation with and without
freeze drying have no effect on the yield of coconut oil. heat cannot be distinguished by standard quality
There is no significant difference in physical properties of parameters. However, SPME/GCMS analysis showed that
supercritically extracted oil compared to cold pressed oil. virgin coconut oil produced by fermentation process with
However, the vitamin E content of coconut oil extracted by and without heat can be distinguished from virgin coconut
SC-CO2 extraction is not significant. Fatty acid oil produced by expeller or centrifugation process based on
compositions showed no significant difference in cold higher levels of volatiles such as acetic acid and octanoic
pressed virgin coconut oil, or supercritical oil or ordinary acid present in virgin coconut oil produced by fermentation
coconut oil prepared by pressing copra. However, phenolic process (Dayrit et al., 2011).
contents of the supercritically extracted coconut oil can be
different. Due to the low polarity of CO2 and the high A detailed study has been conducted to differentiate virgin
polarity of phenolic compounds, solubility of phenolic coconut oil, RBD coconut oil and copra oil (Dayrit et al.,
substances in CO2 is poor. Organic modifiers can be 2007). Virgin coconut oil prepared by centrifugation,
coupled with this extraction and the amount and the nature expeller process, enzymatic treatment, fermentation with
of organic modifier is important for incorporating phenolic and without heat and settling methods were used for the
substances into oil during this extraction (Palma et al., study. According to this study, gas chromatography
2000). analysis done with virgin coconut oil, RBD coconut oil and
copra oil indicates that these oils cannot be differentiated
Attempts have also been made to distinguish between by their fatty acid composition due to similar fatty acid
virgin coconut oil and RBD coconut oil using standard compositions. However, volatile organic matter, moisture

39 40
content and peroxide values are different in these oils. Phenolic substances and the extraction method
Moisture contents of virgin coconut oils extracted under
different conditions varied from 0.05 to 0.12%. RBD It is well-known that phenolic substances protect the
coconut oil had a lower moisture content ranging from 0.01 oxidation of unsaturated fatty acids in triglycerides.
to 0.1 %. Copra oil had a higher average moisture content Phenolic substances are naturally present in seed oils and
at a range of 0.08 to 0.14%. Volatile organic matter these phenolic substances improve the shelf life of oils. The
contents of virgin coconut oils ranged from 0.00 to 0.08%. naturally present phenolic substances of oils can be
RBD coconut oil had no volatile organic matter while copra removed by passing oils through a column containing
oil had a level 1.77% of volatile organic matter by weight. activated charcoal and silicic acid (Waraho et al., 2009).
APCC standards for free fatty acids expressed as lauric acid Such stripped oils are oxidatively less stable than
equivalents is 0.5 %. Average free fatty acid contents of unstripped oils. Phenolic substances can also be added to
virgin coconut oil, RBD coconut oil and copra oil were oils to improve the oxidative stability. Added phenolic
0.131%, 0.021 % and 1.41 % respectively. There were no compounds such as caffeic acid and p-coumaric acid in
significant differences in iodine values of the three types of avocado and coconut oils improved the oxidative stability
oils tested. The average peroxide values were 0.56, 0.98 and nutritional quality. However, those phenolic acids
and 1.48 for virgin coconut oil, RBD coconut oil and copra facilitated the hydrolysis of triglycerides (Sun-Waterhouse
oil respectively and these values are well below the Codex et al., 2011). Adding the carotenoids and vitamin E fraction
Alimentarius peroxide value limit of 15 meq/kg for virgin back to refined, bleached and deodorized palm oil reduced
oils. In the assessment of microbial contamination, it was its atherogenicity (Wilson et al., 2005).
observed that the CFU/mL for most of the virgin coconut
oil and RDB coconut oil samples were below 10 CFU/mL, Total phenol contents of seed oils vary significantly with
which is the APCC standard value. However, there were the extraction conditions. Solvent-extracted oils contain
randomly distributed samples with higher CFU values. The more phenolic substances than virgin oils (Gutfinger,
microbial contamination depends on the quality of 1981). The most striking difference between the traditional
production including the quality of copra but not on the coconut oil extracted by prolonged heating of coconut milk
method of preparation of virgin coconut oil. Production and copra oil is in the phenol content. Total phenol content
quality of copra oil is usually poorer than that of virgin of traditional coconut oil was 618  46 mg while that of
coconut oil. The microbial contamination of the samples of copra oil was 9111 mg as gallic acid/kg oil (Seneviratne
copra oil used in this study was not less than 10 CFU/mL & Dissanayake, 2008). This clearly indicates that extraction
but was only less than 250 CFU/mL range. methods have a remarkable impact on the total phenol
content of coconut oil.

41 42
The effect of the use of cell-wall-degrading-enzyme Finally, the oil was decanted from the deposits at the
preparations during the mechanical extraction process of bottom of the container. According to this study, the
virgin olive oil on the phenolic compounds and maximum total phenol content as gallic acid equivalents of
polysaccharides have been investigated. The use of the coconut oil prepared by chilling coconut milk was 66
enzyme preparations increased the concentration of mg/kg oil and that of traditional coconut oil was 449 mg/kg
phenolic compounds in olive oil. Especially, the contents of oil.
secoiridoid derivatives such as the dialdehydic form of
elenolic acid linked to 3,4-dihydroxyphenylethanol (3,4- The higher phenolic antioxidant contents of coconut oil
DHPEA-EDA) and an isomer of oleuropein aglycon (3,4- prepared at high temperatures can be easily explained by
DHPEA-EA), which have high antioxidant activities, considering the polarities of phenolic substances and
increased significantly in the olive oil (Vierhuis et al., coconut oil. Coconut oil can be considered as a non-polar
2001). substance and oil dissolves in nonpolar solvents such as
hexane. On the other hand, phenolic substances are polar
According to a recent study, virgin coconut oil prepared by substances and, therefore, the solubility of polar phenolic
fermentation process contains higher amount of phenolic substances in nonpolar coconut oil is low. More phenolic
substances compared to virgin coconut oil prepared by substances are incorporated into coconut oil when oil is
other methods. Total phenol contents of virgin coconut oil extracted by wet extraction with prolonged boiling of
prepared by fermentation process by leaving coconut milk coconut milk emulsion. High temperatures improve the
standing for 12 h, chilling coconut milk and RBD coconut solubility of phenolic substances in coconut oil. In the cold
oils measured as gallic acid equivalents are about 250 g/g, extraction methods, the phenolic substances are not
180 g/g and 120 g/g respectively (Marina et al., 2009). properly incorporated into coconut oil due to the mild
The total phenol contents of coconut oil extracted by temperature conditions.
chilling coconut milk and traditional coconut oil prepared
by boiling coconut milk emulsion have been compared In the wet extraction methods, the phenol content of
(Seneviratne et al., 2009). In the cold extraction, coconut coconut oil also depends on the nature of the endosperm
milk was chilled at 10C for 10 h to solidify the lipids. components used to make coconut milk emulsion
Then the aqueous layer was discarded and the lipid block (Seneviratne et al., 2009). White coconut kernel is a poor
was allowed to stand at 30C until it dissolved completely. source of phenolic substances with only 61 mg/kg of
Then the oil layer was separated by centrifugation. In the phenolic substances. Phenolic contents of copra, copra
traditional extraction, coconut milk emulsion was heated to meal (coconut cake or poonac, which is the residue after
100-120C and the water in the emulsion was evaporated. the extraction of coconut oil by pressing copra) and

43 44
coconut testa, are 405 mg/kg, 2156 mg/kg and 3946 mg/kg indicate that cold pressed coconut oil contains lower free
respectively (Seneviratne & Dissanayake, 2006). Therefore, fatty acids compared to coconut oil prepared by
when white kernel is used in the extraction of virgin fermentation process. The lowest and highest acid values
coconut oil under mild temperature conditions, high of the cold pressed coconut oils of the tested varieties were
quantities of phenolic substances are not incorporated into about 0.05 and 0.25 mg KOH/g oil respectively while the
coconut oil. Even when coconut oil is produced by boiling lowest and highest acid values for the coconut oils prepared
coconut milk, the phenolic content of coconut oil will be by fermentation process for the tested cultivars were about
lower if only white coconut kernel is used for the 0.25 and 0.65 mg KOH/g oil respectively (Arlee et al.,
preparation of coconut milk. Coconut oil produced using 2013).
only the white coconut kernel by any method contains
lower amount of phenolic substances. Coconut oil from the 1.2.4 Polycyclic aromatic hydrocarbons
pairings which contain the rind or testa has a higher iodine
value and a higher free fatty acid content compared to the Polycyclic aromatic hydrocarbons (PAHs) are a class of
coconut oil extracted from white coconut kernel or meat as carcinogenic compounds produced due to incomplete
mentioned earlier. Though these differences do not affect combustion of organic compounds. At high temperatures,
the nutritional quality of coconut oil, the oil extracted from certain bonds in organic compounds are broken and small
pairings is considered as low quality coconut oil (Zajew, unstable fragments are formed due to a process called
1956). pyrolysis. These unstable fragments are mostly radicals,
which recombine to give PAHs. The process, which occurs
1.2.3 Coconut hybrids and the quality of coconut oil at high temperatures, is called pyrosynthesis. Due to their
nonpolar nature, PAHs can easily dissolve in oils. Both
Quality parameters of virgin coconut oil from different light and heavy PAH levels have been tested in common
hybrids have been compared. For this study, virgin coconut edible oils such as coconut, groundnut, mustard, olive,
oil was prepared by cold press method and fermentation palm, rice bran, safflower, sesame, soybean and sunflower.
method. The results showed that some hybrids produced Among 296 samples tested from these oils, 88.5% of the
significantly high lauric acid contents compared to their samples contained total PAH levels above 40 g/kg and
parents. However, there was no significant difference in the range was 40.3 to 624 g/kg indicating that PAHs are
lauric acid content of virgin coconut oil extracted by cold common contaminants of edible oils (Pandey et al., 2004).
pressing and fermentation. This study also compares the PAH contamination in seed oils can occur in various stages
free fatty acid contents of virgin coconut oil prepared by of oil preparation. One major source of contamination is
cold press method and fermentation method. The results the seed or kernel drying by direct fire. Refining process

45 46
can remove PAH considerably. Levels of low molecular acetone 60:40 (v/v) (Hossain & Salehuddin, 2012). The
weight PAHs containing up to four aromatic rings can be study showed that soybean oil contained lowest PAH levels
reduced by deodorization. The main process of removing compared to mustard oil and coconut oil. As the study has
PAHs from edible oils is charcoal treatment. been conducted for oil samples available in the market, the
processing methods and conditions of oil preparation are
In coconut oil, PAH contamination occurs during the not clear. However, results indicate that both coconut oil
drying of coconut kernel. Coconut oils prepared from and soybean oil contain levels of PAHs that are below the
kernels dried in the sun, in direct heating kilns and in accepted limits by the World Health Organization. Mustard
indirect heating kilns have been tested for PAH levels oil has relatively high levels of PAH exceeding the WHO
(Wijeratne et al., 1996). According to this study, coconut recommended maximum value for safety.
kernels dehydrated inside the husk and shell by prolonged
storage (ball copra) did not contain any PAH. Smoke dried Various purification steps remove PAH from soybean oil.
coconut kernels contained in the order of 100 g/kg PAHs. The main refining process includes degumming,
Unrefined coconut oil contained 359 g/kg of total PAHs neutralization, bleaching and deodorization. Because of the
and extremely low levels of PAHs (11 g/kg) were presence of PAHs in raw soybeans and solvents, PAH
detected in desiccated coconut, dried using an indirect levels in solvent extracted soybean oils were high and
drying method. The results also indicate that modifying the reached 45.16 μg/kg. Degumming can remove enzymes,
drying method by avoiding direct fire or smoke during microorganisms and other impurities to ensure the stability
copra preparation lowers the PAH levels in coconut oil. of the oil. The PAH content decreased to 12.00 μg/kg with
the removal of impurities in the degumming process
Among PAHs, fluoranthene, pyrene, and because most of the light PAHs in extracted oils were
benzo(a)anthracene are light PAHs while removed. Deacidification is one of the important steps in
benzo(b)fluoranthene, benzo(k)fluoranthene, the soybean oil refining process. Its main purpose is to
benzo(a)pyrene, dibenzo(a,h)anthracene and remove free fatty acids in crude oils and to remove
benzo(g,h,i)perylene are considered as heavy PAHs, which impurities such as pigments, phospholipids, hydrocarbons
are known to be carcinogenic. This study showed that 9 and mucilaginous materials. The deacidification of soybean
5% of PAHs in the tested coconut kernel products were oils is achieved by neutralization of free fatty acids with
light PAHs and heavy PAHs were only 5%. The PAH alkaline solution. The content of PAHs was further reduced
levels of soybean oil, mustard oil and coconut oil have been after the deacidification process and the total amount of
compared. For this purpose, PAHs in oils have been PAHs in neutralized soybean oils decreased to 6.64 μg/kg.
extracted by liquid-liquid extraction using acetonitrile– In the decolorization process, the content of light PAHs has

47 48
a slight decrease showing that the bleaching clay has a little mills. The reason is, in small-scale mills low quality copra
adsorption capacity for light PAHs. The purpose of the with fungal contaminations are used for the oil extraction
deodorization step is to remove unpleasant odors and while better-processed copra is used in large scale mills.
remaining free fatty acids. It further reduced light PAHs According to this study, the tested coconut oils from the
and the total PAHs in the deodorized oil decreased to 1.88 small-scale mills contained a mean value of 186 ppb of
μg/kg. Degumming has the most prominent effect of aflatoxin B1 in 115 samples while coconut oil from large-
decreasing the amount of light PAHs, followed by scale mills contained only about 50 ppb of aflatoxin B1.
neutralization and deodorization (Yu et al., 2014).
In the dry extraction of coconut oil, copra is produced in
1.2.5 Aflatoxin levels various ways. During the rainy season, levels of aflatoxins
in copra and coconut oil increases. Fungal growth occurs in
Many oil seeds such as groundnut, cottonseed, coconut, copra when the moisture level of copra is above 6%.
soybean and sunflower are susceptible to fungal attacks in During any curing process, the moisture level in copra
the field or during storage. The natural mycotoxins decreases to 6%. However, due to high humidity in rainy
produced by Aspergillus flavus and Aspergillus parasiticus season, copra can absorb moisture from the atmosphere so
are the main aflatoxins in seed oils. Humans can be that the moisture levels will be high enough for fungal
exposed to aflatoxins by consumption of contaminated growth. In addition, some mills store copra for some time
food, contributing to an increase in nutritional deficiencies, before pressing for oil production. During this period,
immunosuppression and hepatocellular carcinoma fungal contaminations occur (Samarajeewa &
(Wagacha & Muthomi, 2008). Among the 18 different Arseculeratne, 1983).
types of aflatoxins identified, the major ones are, aflatoxin
B1, aflatoxin B2, aflatoxin G1, aflatoxin G2, aflatoxin M1
and aflatoxin M2, which are produced by Aspergillus flavus
and/or Aspergillus parasiticus.

The aflatoxin contamination in coconut oil occurs during

the preparation of copra. Therefore, the quality of coconut
oil depends on the quality of copra used in the extraction of
coconut oil. According to a study conducted in Sri Lanka,
the aflatoxin levels of coconut oil prepared by small-scale
mills are higher than that of oils prepared in large-scale

49 50
 (saponification) and an unsaponifiable fraction. In
2. Saponifiable fraction unrefined oils, the saponifiable fraction is about 98-99% of
the mass of oil while unsaponifiable fraction amounts up to
of coconut oil 1-2 %. The saponifiable fraction mainly contains
triglycerides and free fatty acids. Triglycerides are derived
Coconut oil contains two fractions, fatty or lipid from the fatty acids and glycerol according to Scheme 2.
fraction and non-lipid fraction. The quality parameters
such as acid value, peroxide value, anisidine value,
iodine value and saponification value are originating O
from the lipid fraction. Among these quality CH2-O C R
parameters, iodine value and saponification value of CH2OH O
coconut oil are not significantly affected by the method
of extraction. Fatty acid composition of coconut oils CHOH + 3 RCOOH CH-O C R
extracted by any dry or wet methods remain reasonably Fatty acid O
CH2OH
similar. However, acid value, peroxide value and
anisidine value vary with the extraction method of Glycerol CH2-O C R
coconut oil. Non-lipid fraction also changes with the
Triglyceride
method of extraction. Health properties of coconut oil
are associated with not only lipid fraction but also non-
lipid fraction. As a result, health properties of coconut Scheme 2. Triglycerides are derived from the fatty acids
oil considerably vary with the method of extraction. and glycerol
Therefore, it is advisable to verify the origin of coconut
oil when coconut oil is used for research purposes or for The chemical composition of a triglyceride varies with the
consumption. number of carbon atoms and the unsaturations (double
bonds) in the R groups. The fatty acids found in the
triglycerides of coconut oil are given in the Table 6. Fatty
2.1 Composition acid compositions of coconut oil have been reported in
several literature sources. Even though the reported
Coconut oil or any other vegetable oil contains a compositions may vary in different sources, such variations
saponifiable fraction or a fraction with an ester functional are not considerably different. The variation of fatty acid
group that can be hydrolyzed under basic conditions composition may be due to several reasons such as maturity

51 52
of coconut, variation of the cultivars, method of extraction
etc. For very accurate studies, it is important to highlight
the above conditions of coconut oil extraction when the
fatty acid composition is reported. Fatty acid compositions
of coconut oil prepared by boiling coconut milk (traditional
coconut oil, TCO) and by pressing copra (copra oil, CO)
extracted from 8-10 months mature ordinary tall coconut
are given in Table 7 as ranges of reported compositions.

The fatty acids in general can be classified based on the

presence of double bonds and the length of the carbon
chain of fatty acids. Fatty acids without double bonds are
classified as saturated fatty acids and those with double
bonds are unsaturated fatty acids. In coconut oil, caproic
acid, caprilic acid, capric acid, lauric acid, myristic acid,
palmitic acid, stearic acid and arachidic acid are saturated
fatty acids and palmitoleic acid, oleic acid and linoleic acid
are unsaturated fatty acids. When a fatty acid contains
more than one double bond, such fatty acids are
polyunsaturated fatty acids. Fatty acids are also classified
as short chain, medium chain and long chain fatty acids
based on the length of the carbon chain of a fatty acid.
However, this classification is not a well-defined
classification. For example, fatty acids with C6 –C14 or C8
– C12 or C8 – C14 have been classified as medium chain
fatty acids. Similarly, fatty acids with C14 and longer
chains or C16 and longer chains are considered as long
chain fatty acids. If C6 - C14 fatty acids are considered as
medium chain fatty acids, coconut oil contains about 83%

53 54
of medium chain fatty acids and 17 % of long chain fatty carbon. An -3 fatty acid contains a double bond between
acids. third and fourth carbon atoms from the  carbon.

Table 7. Fatty acid composition of coconut oil

Common name TCO CO Reported 1 2 3
range CH3CH2CH=CH(CH2)nCOOH

Caproic acid 0.63  0.06 0.53  0.04 0.5 – 0.8
Caprilic acid 9.0  0.0 8.6  0.1 5–9
Figure 3. An -3 fatty acid
Capric acid 6.5  0.1 6.4  0.2 4 – 10
Lauric acid 49.6  0.2 48.7  0.2 44 - 52
Myristic acid 19.2  0.1 18.9  0.1 13 – 21 The most important -3 essential fatty acid is linolenic acid
which contains three double bonds with one double bond at
Palmitic acid 7.2  0.1 7.6  0.2 8 – 11
Stearic acid 2.4  0.1 2.4  0.1 1-4 -3 position. The most common -6 fatty acid is linoleic
Arachidic acid Not detected Not detected 0.1 – 0.4 acid which contains two double bonds with one at -6
Palmitoleic acid Not detected Not detected 0.1 – 0.2 position. The data in the Table 7 indicate that coconut oil
Oleic acid 4.5  0.1 4.9  0.2 5-8 is not a rich source of essential fatty acids.
Linoleic acid 1.1  0.1 1.3  0.1 1.1 – 1.3
TCO = traditional coconut oil; CO = copra oil 2.1.1 Analysis of fatty acids

To further understand the chemical and nutritional aspects Fatty acid composition of coconut oil or other vegetable
of coconut oil, it is necessary to discuss about certain oils can be determined by gas-liquid chromatography (GC).
common terms that are used in the nomenclature of fatty For this purpose, triglycerides in the oils are converted to
acids. Essential fatty acids are the fatty acids that are more volatile fatty acid methyl esters. This esterification
biologically important yet cannot be synthesized by can be done in various ways. In the acid hydrolysis process
humans. The essential fatty acids must be obtained through the oil is reacted with a large excess amount of anhydrous
diet. These fatty acids include long chain polyunsaturated methanol in the presence of sulfuric acid at about 80 C in
fatty acids such as linolenic acid and linoleic acid. There a closed vessel (Garcés & Mancha, 1993). Using this
are two classes of essential fatty acids, namely, -3 fatty method, free fatty acids can be esterified and triglycerides
acids and -6 fatty acids. The methyl carbon at the distal can be trans esterified as one pot reaction. Fats and oils
end of the carbon chain of fatty acid is considered as the  can also be efficiently and accurately methylated by boron
trifluoride and methanol. In this method, oil sample in a

55 56
screw-capped test tube is mixed with NaOH and methanol system. Signals in the GC chromatogram were identified
and heated in boiling water for 5 min. Then 20 % BF3 in by comparison of the retention times of the signals with
methanol is added and the mixture is heated further for 5 those of authentic fatty acid methyl ester standards.
min at 100 C. The fatty acid methyl esters can then be
extracted with n-hexane. The conditions used in the
analysis of fatty acid methyl esters by GC may vary with
the nature of fatty acids, type of capillary column, and
several other factors. It is important to do some trial and
error experiments with fatty acid methyl ester standards to
develop optimum conditions for GC analysis. The GC
chromatogram of fatty acid methyl esters prepared from a
copra oil sample is given in Figure 4. To extract this oil
sample, 8-10 months mature coconuts from ordinary tall
coconut cultivars were used and copra was prepared by sun
drying chopped coconut kernels for two weeks.

A concentrated extract of methyl esters of the fatty acids

present in coconut oil was subjected to gas
chromatography. The chromatogram in Figure 4 was
recorded using a Thermo Finnigan Trace gas Figure 4. GC chromatogram of fatty acid methyl esters
chromatograph equipped with a capillary column RtxR- prepared from copra oil
wax (Crossbond with PEG, 30 m x 0.32 mm i.d. 0.25 m)
A flame ionization detector (FID) was used for the analysis. 2.1.2 Glycerides in coconut oil
The injector and the detector temperatures were set at 230
C and 250 C respectively. Helium gas was passed as Even though fatty acid composition of coconut oil is well
career gas at a flow rate of 0.5 mL/min and analyses were known there is not much information available about the
performed on split mode (split ratio 100:1). Column composition triglycerides present in coconut oil. In the
temperature was programmed at 130 C (3 min), 130 C to analysis of fatty acid composition, the fatty acids in
210 C at 45 C/min and 210 C (12 min). The fatty acid triglycerides are transesterified with methanol. Therefore,
methyl ester extract (0.4 L) was injected into the GC the glycerides are broken down during this analysis. Early
workers have attempted the isolation of individual

57 58
triglycerides from coconut oil by fractional distillation at
very low pressures. Identified glycerides included 3. Unsaponifiable
caprylolauromyristin, myristodilaurin, laurodimyristin,
palmitodimyristin and stearodipalmitin. Among the
triglycerides, 84% are fully saturated. Component
fraction of coconut oil
triglycerides have been more successfully determined by The quality parameters such as acid value, peroxide value,
systematic crystallization of the oil from acetone (Dale & saponification value and iodine value are related to the
Meara, 1955). saponifiable or lipid fraction of coconut oil. As mentioned
in Chapter 2, the saponifiable fraction in edible oils is about
98-99 % by weight. Unrefined oils contain an
unsaponifiable fraction which amounts up to 1-2 % by
weight. The chemical composition of the unsaponifiable
fraction is discussed in this chapter. As a general statement,
fatty acid composition of coconut oil is more or less same
in all the coconut oils extracted by different methods.
However, the unsaponifiable matter content varies
significantly with the method of extraction.

3.1 Metal content

Metals in coconut oil may result from natural metal content
of coconut oil and the metals that are present as
contaminants. Metals such as iron are known to promote
the oxidation of oils (Kanner et al., 1988). Metal content in
coconut oil can be detected by atomic absorption
spectrometry (AAS). For this purpose, it is better to extract
metals in coconut oil into an aqueous layer. About 100.0 g
of coconut oil is accurately weighed and mechanically
shaken for 8 h with 1 M HNO3. This procedure can be
repeated four more times with new aliquots of 1 M HNO3

59 60
for the same oil sample to make sure the extraction of not contaminated with metals in this way. Therefore, the
metals is complete. The aqueous layer can be concentrated metal contents of these oils are lower than those of copra
to about 50 mL and the metals can be analyzed by AAS. oil. The effect of Fe3+ and Cr3+ on the peroxide formation
The metal contents of coconut oils analyzed by the AAS is shown in Figure 5a and Figure 5b respectively.
are given in the Table 8.
(a)
Table 8. Metal contents in Traditional coconut oil (TCO)
and copra oil (CO) Figure 5.
3.2 Blank Effects of Fe3+

Peroxide value (H2O2mg/ml)

Metal Content (ppm) Fe 2ppm
Fe 6ppm (a) and Cr3+ (b)
Fe Cr Zn Mn Cu Mg 2.4
Fe 10ppm
on the peroxide
formation in
T 0.60 ± 0.004 ± 0.84 ± 0.041 ± 0.013 ± 0.06 ± 1.6 coconut oil
C 0.07a 0.000a 0.30a 0.003a 0.000a 0.01a
O 0.8

C 5.7 ± 0.02 ± 4.4 ± 0.038 ± 0.015 ± 0.09 ±

O 1.0b 0.00b 1.0b 0.008a 0.001a 0.01a 0
0 5 10 15 20 25 30 35
Time (Days)
Each data point represents the mean of ten replicates  S.E; (b)
Different superscript letters in a same column denote a 0.4
significant difference (p<0.05) by MINITAB 2-sample t test.
Blank
Cr 2ppm

Peroxide value(H2O2 mg/ml)

Cr 6ppm
Table 8 shows that the Fe, Cr and Zn contents of 0.3
Cr 10ppm
commercial coconut oil or copra oil are significantly higher
than those of traditional coconut oil. As mentioned in 0.2
Chapter 1, the extraction of copra oil involves the crushing
and grinding of copra in mills followed by pressing.
Coconut oil may get contaminated with the metals during 0.1
this milling process. However, traditional coconut oil
prepared by boiling coconut milk and virgin coconut oil are
0
0 10 20 30 40
Time(Days)

61 62
The rate of formation of peroxides in coconut oil at 2.0, Organic compounds
6.0, and 10.0 ppm Fe3+ concentrations were 0.00761 
0.00012, 0.03853  0.00090 and 0.10656  0.00576 H2O2 The organic compounds in the unsaponifiable fraction of
mg/mL day respectively (Seneviratne & Dissanayake, coconut oil can be fractionated by the Florisil column
2003). It is hard to find a suitable coconut oil sample chromatography and the compounds can be identified by
containing no metals to be used as the control sample in gas chromatography. Both polar and nonpolar organic
these experiments. However, a coconut oil sample with compounds have been identified in the unsaponifiable
low, but known concentration of metals can be used for this fraction of coconut oil (Moura Fe et al., 1975).
purpose. The rate of formation of peroxides in the control
with 0.59 ppm Fe3+ was 0.00440  0.00009 H2O2 mg/mL 3.2 Hydrocarbons
day. As shown in the Figure 5b, the effect of Cr3+ on the
peroxide formation in coconut oil is not so pronounced as At least 29 hydrocarbons including squalene with chain
that of Fe3+. The rates of formation of peroxides in coconut lengths C17 to C32 have been identified by gas
oil at 2.0, 6.0 and 10.0 ppm Cr3+ concentrations are chromatography. The hydrocarbons include both straight
0.00523  0.00003, 0.00745  0.00002 and 0.00874  chain and branched hydrocarbons. The bleaching and
0.00023 H2O2 mg/mL day respectively while the control deodorization of coconut oil removes most of these
with 0.004 ppm Cr3+ showed a rate of 0.00440  0.00009 hydrocarbons to undetectable levels.
H2O2 mg/mL day. Other metal ions such as Zn2+, Mn2+,
Cu2+ and Mg2+ do not promote the peroxide formation in 3.3 Alcohols
coconut oil to any detectable extent. Peroxide contents and
free fatty acid contents are important factors that affect the Normal aliphatic and triterpenoid alcohols in the range C12
oxidative stability of coconut oil. Rate of free acid to C29 are present in the unsaponifiable fraction. At least
formation is also affected by the metal ions present in 17 alcohols have been reported. N-hexadecanol,
coconut oil. However, Fe3+ and Cr3+ concentrations up to isodocosanol, n-pentacosanol and n-hexacosanol are some
10.0 ppm with respect to each ion in coconut oil do not of the examples. Cycloartenol was the major triterpenoid
significantly increase the free acid formation. Even though alcohol present in coconut oil. In addition to these alcohols,
the free acid formation improves with the metal sterols such as campesterol, stigmasterol and -sitosterol
concentration at higher metal concentrations, it is not have been identified in coconut oil (Fedeli et al., 1966).
practically important because all the tested coconut oil
samples contain Fe3+ or Cr3+ below 10 ppm.

63 64
3.4 Phenolic compounds substances. The major contributor to the phenolic
compounds in coconut oil is the coconut testa.
Usually the phenolic compounds in vegetable oils add
nutritional value to the oils. Phenolic substances are Table 9. Phenolic compounds in various endosperm
important antioxidants that can protect oil against components of coconut
autooxidation. There is a linear relationship between
polyphenol content and oxidative stability of virgin olive Endosperm component Phenol content mg/kg
oil during storage at 60 C. There is a linear correlation White coconut kernel 61  08
between the total phenol content and oxidative stability in
olive oil (Tsimidou et al., 1992). The phenolic content Testa 3946  34
depends on the method of extraction of oil. For example, Coconut cake (poonac) 2156  16
solvent extracted oils are richer in polyphenols than the
virgin oils (Gutfinger, 1981). Phenolic contents of coconut Copra 405  08
oil also depend on the method of extraction. Coconut oil
prepared by pressing copra contains about 75 mg/kg of During the extraction of coconut oil, the phenolic
phenolic substances while coconut oil prepared by boiling substances of these coconut components mix with coconut
coconut milk contains more than 500 mg/kg of phenolic oil in different quantities depending on the method and
substances (Seneviratne & Dissanayake, 2005). Virgin conditions of extraction. Usually the brown portions such
coconut oil also contains relatively lower amounts of as coconut testa and lignin parts in the shell of coconut are
phenolic substances that may amount up to 60 – 70 mg/kg. removed and only white coconut kernel is used to prepare
All the given phenolic contents here are expressed as gallic virgin coconut oil. Therefore, the amount of phenolic
acid equivalents and the contents were determined by substances present in virgin coconut oil is low. Phenol-rich
Folin-Denis colorimetric method (Perry et al., 2001). endosperm components are not removed during the
extraction of copra oil or traditional coconut oil. Therefore,
Table 9 shows the contents of phenolic compounds present higher phenolic contents can be expected for commercial
in various endosperm components of coconut. The results copra oil and traditional coconut oil.
show that coconut testa is a rich source of phenolic
compounds (Seneviratne & Dissanayake, 2006). White In addition to the nature of endosperm components, the
coconut kernel contains only a small amount of phenolic extraction temperatures of coconut oil are also important to
facilitate the incorporation of phenolic substances into

65 66
coconut oil. High temperatures favor the incorporation of endosperm that is used to extract coconut oil. It is clear
phenolic substances into coconut oil. Under low according to these data that high temperatures are essential
temperature conditions that are used in the extraction of for the efficient incorporation of phenolic compounds into
virgin coconut oil and copra oil, phenolic compounds coconut oil and at mild temperature conditions that are used
poorly mix with coconut oil. The reason for this poor in the extraction of virgin coconut oil, phenolic compounds
incorporation of phenolic substances into coconut oil is due are not efficiently incorporated even when phenol-rich
to large polarity difference between phenolic substances endosperm components are used.
and coconut oil. Coconut oil is a relatively nonpolar
substance while phenolic compounds are highly polar Table 10. Total phenolic contents of coconut oils
substances. The mixing of these too needs some extreme
conditions that are used in the extraction of traditional Components of endosperm Total phenol content mg / kg oil
coconut oil by boiling coconut milk. The first step of the VCO TCO
extraction of traditional coconut oil is the scraping coconut
kernel and squeezing the scraped coconut kernel with water WK 62  2 78  2
to produce the emulsion of coconut milk. During the WK + CT 64  2 250  4
scraping process, testa and the parts of lignin-rich shell are
also mixed with the white coconut kernel. Phenolic acids WK + CW 65  3 358  4
and flavonoids are polar compounds that can easily WK + CT + CW 66  3 449  4
dissolve in the aqueous phase of coconut milk. During the
a
evaporation of water from coconut milk as a result of Each data point represents the mean of six replicates ± standard
boiling the mixture, these phenolic compounds are slowly deviation. WK = white kernel, CT = coconut testa, CW =
incorporated into traditional coconut oil. coconut water

Table 10 shows the phenolic contents of virgin coconut oil 3.4.1 Identification of phenolic compounds
and traditional coconut oil extracted using different Phenolic compounds present in coconut oil can be
combinations of endosperm components (Seneviratne et al., identified by high performance liquid chromatography
2009). The data in Table 10 indicate that there is no (HPLC) with fluorescence or diode array detection (Mateos
significant variation of the total phenol content of virgin et al., 2001; Montedoro et al., 1992). The identification
coconut oil with the composition of the endosperm. was primarily done by comparison of the retention times of
However, the total phenol contents in traditional coconut the authentic standards with the signals in the
oil vary significantly with the composition of the chromatogram. Caffeic acid, p-coumaric acid, ferulic acid

67 68
and (+/-)-catechin are among some the phenolic More complex profile of phenolic substances in traditional
compounds present in coconut oil. Figures 6, 7, and 8 coconut oil indicates that, in addition to the high phenol
show the HPLC chromatograms of the phenolic fractions of content traditional coconut oil also contains several
commercial coconut oil (copra oil), virgin coconut oil and different phenolic substances. Surprisingly high total
traditional coconut oil respectively. HPLC methods have phenol contents have been reported for copra oil and virgin
been used to quantify phenolic compounds in virgin olive coconut oil (Nevin & Rajamohan, 2004). Even if the
oil (Bandino, 1997). The quantities of phenolic compounds phenolic contents seem to be expressed as caffeic acid in
present in traditional coconut oil are also given in Figure 8. this case, such high phenolic contents were not evident by
The quantification has been done by comparison of the the HPLC studies shown above or by colorimetric studies
signals areas using calibration curves. conducted by us.

Figure 7. HPLC chromatogram of the phenolic fraction of

virgin coconut oil (1) gallic acid (28.1  10.5), (2) (-)-
epigallocatechin (26.7  1.7), (3) syringic acid (1.4  0.1)
(means of five samples  standard deviation, mg/kg oil)
(Seneviratne et al., 2009)
Figure 6. HPLC chromatogram of the phenolic fraction of
copra oil: 1, caffeic acid; 2, ferulic acid; 3, (+/-)-catechin
(Seneviratne & Dissanayake, 2008)

69 70
 Figure 8 indicates that traditional coconut oil is the richest
coconut oil with phenolic compounds. This indicates that
most of the phenolic substances present in coconut oil are
thermally stable and these compounds are not destroyed at
high temperatures that are used in the extraction of
traditional coconut oil. In addition, high temperatures
favour the more efficient incorporation of phenolic
compounds into coconut oil. Quantities of some identified
phenolic substances in TCO and CO are compared in Table
11.

Table 11. Comparison of phenolic substances present in

traditional coconut oil (TCO) and copra oil (CO)

Compound Quantity (mg/kg)

Figure 8. HPLC chromatogram of the phenolic fraction of
CO TCO
traditional coconut oil (1) gallic acid (20.2  10.1), (2) (-)- (+ ⁄- )-Catechin 0.87 ± 0.1 2.9 ± 0.4
epigallocatechin (26.7  1.7), (3) (+)-catechin (81.7  Caffeic acid 0.13 ± 0.06 3.0 ± 1.1
22.7), (4) p-hydroxybenzoic acid (4.8  1.0), (5) (+)- p-Coumaric acid 0.34 ± 0.01 2.0 ± 0.2
epicatechin (1.4  0.6), (6) caffeic acid 4.6  1.5), (7) Ferulic acid 0.31 ± 0.2 3.3 ± 1.2
syringic acid 4.1  0.9 and ferulic acid 22.1  8.9 (means Unidentified phenolic acids 11.2 ± 2.1 97.2 ± 5.7
of five samples  standard deviation, mg/kg oil) Unidentified flavonoids 1.6 ± 0.3 10.8 ± 5.0
(Seneviratne et al., 2009) Each data point represents three replicates ± SE (Seneviratne &
Dissanayake, 2008).
It is also common belief that low temperatures used in the
extraction of virgin coconut oil help preserve thermally The presence of these compounds has been further
stable phenolic substances in coconut oil. Higher confirmed by mass spectroscopy coupled to liquid
temperatures may either deactivate or oxidize some chromatography (Seneviratne & Dissanayake, 2008). For
phenolic substances. Based on this argument it is this purpose, a mass spectrometer coupled to high
reasonable to expect poor antioxidant contents in copra oil performance liquid chromatograph (LC-MS) can be used.
and traditional coconut oil. However, the chromatogram in Figure 9 shows the mass chromatogram of ferulic acid. The

71 72
mass fragments for this analysis was generated by
electrospray ionization technique. The mass fragment (M-
H)- generated by this technique is shown in the Figure 9. Electrospray
chromatogram. The molecular mass of ferulic acid is 194 ionization mass spectrum of
and the (M-H)- fragment (193) confirms the presence of ferulic acid (Seneviratne &
this phenolic acid. Dissanayake, 2008)

Table 12 shows the data on mass spectroscopic analysis of

phenolic substances. In addition to the identification of
phenolic substances by mass spectroscopy coupled to liquid
chromatography, selected ion recording (SIR) mode was
used to identify hydroxytyrosol and vanillic acid.

Table 12. The m/z values for (M-H)- ions generated by

electrospray ionization mass spectroscopy

Name Molecular weight m/z of (M-H)-

Caffeic acid 180 179
p-Coumaric acid 164 163
Ferulic acid 194 193
Catechin 290 289

The total phenol contents of cold pressed coconut oils were

slightly higher compared to coconut oil prepared by
fermentation of coconut milk for each cultivar tested.
However, the differences are not very important
nutritionally as the values are very close to each other
(Arlee et al., 2013).

73 74
Figure 10 shows some structures of phenolic substances compounds from coconut cake can be successfully
that are present in coconut oil. Vanillic acid, caffeic acid, p- incorporated into coconut oil by a heat treatment method
coumaric acid, ferulic acid and hydroxytyrasol are known
to be present in olive oil (Montedoro et al., 1993). Even Figure 10.
though the detailed studies of the beneficial properties of The structures
the phenolic extracts of copra oil or traditional coconut oil of some
have not been reported, such properties can be expected for phenolic
coconut oil too because of the presence of similar phenolic substances
substances in coconut oil as in olive oil. Phenolic present in
compounds in olive oil are responsible for pharmacological coconut oil
properties (Maestro-Durán et al., 1994), anticancer
properties (Monti et al., 2001), antimicrobial properties
(Brenes et al., 1992, 1995) and antioxidant properties
(Baldioli et al., 1996; Popadopoulos et al., 1991; Manna et
al., 1997). In addition, several health benefits including the
reducing the risk of coronary heart disease by olive
phenolics are known (Visioli & Galli, 1998). Phenolic
compounds are also responsible for oxidative stability and
organoleptic properties of the oils. Even though coconut oil
contains several phenolic substances whose beneficial
properties are already known, the commercially available
coconut oil (copra oil) contains only up to 90 mg/kg oil
phenolic compounds. Table 9 shows that coconut cake is a
rich source of phenolic antioxidants. This suggests that the
quality of copra oil can be improved by the incorporation of
phenolic substances from coconut cake into copra oil. As
mentioned above, phenolic compounds are polar substances
while coconut oil is a relatively nonpolar substance. Due to
this difference in polarity it is not possible to dissolve
phenolic substances in coconut oil. However, phenolic

7573 7674
without affecting the fatty acid composition of coconut oil
(Seneviratne & Dissanayake, 2006, Patent).

The antioxidant activity of the phenolic substances is

related to the ability to donate hydrogen to a free radical.
The donation of hydrogen stabilizes the peroxy radicals so
that the propagation steps of radical reactions will be
inhibited. The mechanism of the antioxidant activity of
hydroxytyrosol by hydrogen donation is given in the
Scheme 3. Studies conducted with flavonoids have
indicated that the antioxidant activity is correlated with the
number of hydroxyl substituents (Rice-evans et al., 1996; Scheme 3. Mechanism of the antioxidant activity of an
Cao et al., 1997). In particular, o-diphenols mostly ortho diphenol (Visioli & Galli, 1998).
contribute to the antioxidant activity. Formation of an
intramolecular hydrogen bond between free hydrogens of
the hydroxyl groups and phenoxyl radicals improve the 3.5 Vitamin E contents
stability of radicals thereby improving the antioxidant
activity. Due to this reason o-diphenols show better Vitamin E content in coconut oil is usually low and the
correlations with the antioxidant activity compared to other quantities are negligible in coconut oil extracted by dry
phenolic compounds. methods. However, virgin coconut oil extracted by cold wet
methods contains higher amounts of vitamin E. Vitamin E
One of the simple and important methods of estimating the or tocopherols are sensitive to high temperatures and
antioxidant activity is the DPPH radical scavenging processing conditions of copra. Due to this reason,
activity. The free radical scavenging activity of olive oil tocopherols are not usually detected in copra oil. However,
phenolics have been reported by Visioli & Galli, (1998). mild temperature conditions are used in the extraction of
Both in vitro and in vivo studies have shown that the virgin coconut oil. Therefore, there are claims that virgin
phenolic substances extracted from coconut oil also show coconut oil contains tocopherols (Nevin & Rajamohan,
excellent antioxidant activities (Seneviratne et al., 2009). 2004). Comparison of tocopherol contents of cold pressed
and fermented coconut oils from different coconut cultivars
indicate that the cold pressed method provides highest
tocopherol content in coconut oil. According to this study,

77 78
cold pressed coconut oil contains tocopherol contents
ranging from 3.17 mg/100 g oil to 5.78 mg/100 g oil for 4. Industrial uses and
different coconut cultivars. Coconut oil produced by
fermentation process contained tocopherol contents ranging
from 2.14 mg/100 g oil to 4.15 mg/100 g oil for different
other applications of
coconut cultivars. coconut oil
Vitamin E and phytosterols in virgin coconut oil prepared
by chilling coconut milk and copra oil have been compared 4.1 Lubrication
and the results are given in Table 13 (Nevin & Rajamohan,
2009). Studies also show that not only vitamin E levels but Because of the environmental problems of mineral oils,
also vitamin A levels are higher in virgin coconut oil there is growing interest in the development of plant-based
compared to copra oil. When exposed to sunlight for oils as lubricants. The biodegradability, high viscosity, low
several days, vitamin content of virgin coconut oil evaporation loss and high flash point make vegetable oils
decreased sequentially, which confirms the loss of vitamins good candidates as the base for lubricants. However, the
from copra when exposed to UV radiation from sunlight thermal and oxidative properties of vegetable oils depend
(Nevin & Rajamohan, 2006). on the fatty acid composition. The presence of high
percentages of polyunsaturated fatty acids decreases the
Table 13. Vitamin E and phytosterol contents of coconut thermal and oxidative stability of oils. Coconut oil contains
oils about 85 % of short and medium chain saturated fatty
acids. Due to this reason, a higher thermal stability can be
Virgin coconut oil Copra oil expected for coconut oil. Coconut oil is widely used as a
Vitamin E (g/100g) 30.87 12.76 lubricant in some two-stroke engines in Kerala, a Southern
Campesterol (ng/dL) 17.00 25.07 state of India and studies on tribological performance of
Stigmasterol (ng/dL) 63.13 57.05 coconut oil have been reported (Jatadas et al., 2007).
-Sitosterol (ng/dL) 73.03 57.00 Thermogravimetric studies under nitrogen and oxygen
(Nevin & Rajamohan, 2009). environments at high temperatures have shown that
coconut oil has the lowest weight gain compared with
sunflower oil and sesame oil, indicating that coconut oil has
the highest oxidative stability among the oils tested (Nair &
Nair, 2006). The oxidative stability of vegetable oils can be

79 80
tested by monitoring the weight gain of oil during standing
or under other experimental conditions. Weight gain occurs O
as a result of the formation of peroxides in vegetable oils.
H2C O C-(CH2)10-CH3

4.2 Biodiesel O

There is considerable attention these days about the search HC O C-(CH2)10-CH3 + 3 CH3OH
of alternate fuels due to the fluctuation of crude oil prices O
and environmental concerns. Vegetable oils and animal fats
have shown to be the potential alternatives for petroleum H2C O C-(CH2)10-CH3
based fuels. However, these oils cannot be directly used in
Molecular weight 638
many diesel engines. The triglycerides present in these oils
have high molecular weights and their volatility is lower
compared with petroleum based diesel. Due to this reason,
use of vegetable oils in the diesel engines lead to poor fuel
atomization, poor cold engine start-up and formation of
gums and other deposits. The high molecular weight O H2C OH
triglycerides in vegetable oils can be ‘broken’ to smaller
molecular weight fragments by transesterification of the 3 CH3(CH2)10 C-O-CH3 + HC OH
triglycerides with methanol or other short chain alcohols. In
the petroleum industry, large molecular weight fragments Molecular weight 214 H2C OH
of crude oil are broken by cracking. Similarly, vegetable Molecular weight 92
oils are also cracked by this transesterification. The major
fatty acid present in coconut oil is lauric acid (~50%). To Scheme 4. Reduction of molecular weight by
illustrate how the transesterification reduces molecular transesterification
weight, let us assume that coconut oil contains a
triglyceride with only lauric acid as the fatty acid. How the The resultant methyl ester of lauric acid has the molecular
molecular weight is reduced during the transesterification is weight 214. Reduction of molecular weight also causes the
shown in Scheme 4. reduction of viscosity during transesterification. This
mixture of methyl esters and glycerol is called biodiesel.

81 82
The viscosity of biodiesel is close to that of petroleum- Coconut oil itself has been used as a biofuel. For example,
based diesel. The cetane values and flash points of coconut oil blended with diesel can be used in standard
biodiesel are higher and the caloric value of biodiesel is diesel engines. However, the durability of engine is
lower compared to petroleum-based diesel. In other words, questionable when the blends contain more than 20 % of
the energy that is generated by burning a known amount of coconut oil or other vegetable oils. Deposits in the pistons,
biodiesel is lower. After the transesterification, the mixture valves, combustion chambers and injectors may cause loss
contains methyl esters of fatty acids, glycerol, catalysts, of engine power. Instead of using coconut oil blended with
unreacted methanol and water. The fatty acid methyl esters diesel in diesel engines, engines can be adapted for coconut
can be separated and used as higher quality biodiesel. The oil. The adaptations can also be used to start and stop on
physical separation can be done due to the higher density of regular diesel where it can be switched to coconut oil when
fatty acid methyl esters. Glycerol can be separated as a the engine is running at high temperatures. It is also
byproduct of biodiesel production. possible to make necessary changes in the fuel system in
diesel engines to start and stop on pure coconut oil.
Transesterification can be catalyzed by both acid and base Adapted injectors, dedicated fuel pumps and extra filters
catalysts. For the acid catalysis, sulfuric acid is used and for can be used.
the base catalysis potassium hydroxide or sodium
hydroxide is used. Formation of potassium or sodium salts Oil blends have been prepared by mixing coconut oil with
of fatty acids (soaps) is a problem in the base catalyzed diesel in various proportions. There is a direct relationship
esterification. The formation of soap reduces the yield of between the nature of fuel and lubrication characteristics of
biodiesel and creates problems in product separation. Acid engines. During the internal combustion in engines,
catalysis is a slow reaction and the presence of even trace unburned fuel and or products of incomplete and complete
amounts of acids in biodiesel causes corrosion in engines. combustion of the fuel pass through the piston rings and
Both acid catalysts and base catalysts are homogeneous cylinder into lubrication oil. Under these conditions, the
catalysts. To minimize the problems associated with the quality of lubricating oil may get degraded. The degraded
product separation, heterogeneous catalysis has been lubricating oils cause greater wear of the friction surfaces
proposed. Production of biodiesel from coconut oil using thereby reducing the life time of engines. The presence of
heterogeneous catalytic systems such as ZrO2, ZnO, SO42- wear metals such as Fe (iron), Cr (chromium), Cu (copper),
/SnO2, SO42-/ZrO2, KNO3/KI zeolite and KNO3/ZnO2 has Al (aluminum) and Pb (lead) in the used oil in quantities
been reported (Jitputti et al., 2006). beyond the expected levels from normal engine wear is an
indication of unusual wear of engines. Experiments carried
out using coconut oil up to 50% mixed with diesel indicate

83 84
that wear metals and contaminant elements such as Si being used as a popular ingredient in many skin care and
(silicon), B (boron), and V (vanadium) increase with the hair care products.
increasing of the proportion of coconut oil in diesel (Kalam
& Masjuki, 2005). Increasing the amount of coconut oil in 4.4 Other chemical applications
diesel reduces the additive elements such as Zn (zinc), Ca
(calcium), P (phosphorus), and Mg (magnesium) in the 4.4.1 Oleochemicals
used lubricating oil. Soot and sulphation also decrease with
increasing coconut oil in the blended fuels due to reduced Coconut oil is also important in the preparation of oleo
aromatic and sulfur compounds in coconut oil compared chemicals. Oleochemicals are chemicals derived from plant
with diesel. However, water concentration in blended fuels and animal fats. Basic oleochemical substances like fatty
increases with the use of more than 30 % of coconut oil. acids, fatty acid methyl esters (FAME), fatty alcohols, fatty
amines and glycerols are formed by various chemical and
4.3 Moisturizers and beauty products enzymatic reactions. The fatty acid composition of coconut
oil falls within the carbon-chain spectrum desired for the
Coconut oil is traditionally used as a beauty staple in many production of oleochemicals. The caproic to capric (C6–
tropical countries. It is well known for its applications in C10) fatty acid fractions are good materials for plasticizer
soap industry and other beauty care products. The range alcohol and for polyol esters. The latter are used in
application of virgin coconut oil compared with mineral oil high-performance oil for jet engines and for a new
as a therapeutic moisturizer for mild to moderate xerosis, a generation of lubricants. These fractions are also used in
skin condition characterized by dry, rough, scaly, itchy skin preparation of medium-chain triglycerides, a highly valued
associated with a defect in skin barrier function has been dietary fat. The C12–C18 fractions are the primary raw
reported. In addition, coconut oil also has been shown to materials for detergent-grade fatty alcohols (Behr et al,
have skin antiseptic effects (Agero & Verallo-Rowell, 2008). Lipases from various microbial sources are used for
2004). Coconut oil formulated into cream has been shown hydrolysis of coconut oil triglycerides to its component
to retain antimicrobial activity of coconut oil (Oyi et al., fatty acids (Fu et al., 1995). Fatty alcohols can be produced
2010; Obi et al., 2005). Coconut oil has also been shown to by the heterogeneously catalyzed high-pressure
moisturize dryness and remove Staphylococcus aureus hydrogenation of methyl esters or fatty acids. The
resulting from atopic dermatitis (Verallo-Rowell et al., unsaturated fats and oils can be derivatized catalytically by
2008; Evangelista et al., 2014). Therefore, due to its functionalization, oligomerization, oxidation or metathesis
moisturizing effect and antimicrobial activity, coconut oil is to introduce new functional groups into the oleochemical

85 86
substrate. The carbon chain length can be increased or
decreased, or branching in the fatty chain can be 5. Coconut oil and health
introduced. Products with completely new properties and
areas of applications are available due to these catalytic The comparison of quality parameters and fatty acid
variations of fats and oils (Behr et al., 2008). composition of coconut oil with those of other oils shown
in Table 14 clearly indicates that coconut oil is a cooking
4.4.2 Metal extraction oil with unique composition. Its composition is unique
because 90 % of fatty acids are saturated, 80 % of the fatty
Coconut oil has been tested in metal extraction. N- acids have chain lengths fewer than 16 carbons, nearly half
phenylhydroxamic acid ligand, synthesized starting from of its fatty acids is lauric acid and over 90 % of the fatty
coconut oil has been used in the liquid-liquid extraction of acids can be considered as short or medium chain fatty
Ti(IV), Fe(III), Fe(II) and Al(III) (Gunawardena & acids. Triglycerides with short chain fatty acids are
Asirwatham, 1982). Conventional methods for heavy metal hydrolyzed more easily and are readily absorbed by blood.
removal include chemical precipitation, electrolytic These short chain fatty acids are readily oxidized in the
recovery, electrodialysis, ion exchange and solvent body to produce carbon dioxide to generate energy while
extraction methods. Several studies also deal with the use only traces are deposited in mammalian cells.
of supported liquid membranes (SLMs). Coconut oil has
been also tested as a component in the preparation of Coconut oil contains only about 1-2 % of essential fatty
SLMs. Use of di(2-ethylhexyl)phosphoric acid-coconut oil acids. Therefore, coconut oil cannot be considered as a
supported liquid membrane for separation of copper ions good source of essential fatty acids and those who consume
from copper plating wastewater has been reported coconut oil as the major source of fatty acids will have to
(Venkateswaran et al., 2007). take essential fatty acids from other sources. Histological
lesions have been noted in rats fed with hydrogenated
coconut oil without essential fatty acids (Stromby &
Wigand, 1963). This observation has been attributed to the
deficiency of essential fatty acids.

87 88
Table 14. Fatty acid composition and quality parameters of monolaurin which has shown antiviral, antibacterial and
common cooking oils antiprotozoal properties, both in vitro and in vivo
experiments. Monolaurin is the mono ester of triglycerol
Oil SFA MUFA PUFA AV IV SV and it can destroy lipid-coated viruses including influenza
Coconut 91 6 3 0.2 6-11 250-264 viruses. When eating coconut oil, a small percentage of
lauric acid is transformed into monolaurin. Mother’s milk
Soy bean 15 26 57 0.2 120- 180-200 also contains a large amount of lauric acid and disease
143 fighting monolaurin is produced in the body of the babies.
The virocidal effects of monolaurin compounds on
Sunflower 12 23 65 0.25 110- 188-194
enveloped RNA and DNA viruses have been shown
143 (Lieberman et al., 2016). The envelope of these viruses is a
Corn 17 24 59 0.25 102- 187-193 lipid membrane and the antiviral activity is due to
monolaurin that stabilizes the lipids and phospholipids in
130 the envelope of viruses. However, most of this research
Sesame 13 42 45 0.25 103- 180-200 about antiviral activity is based on monolaurin and not on
coconut oil.
116
Olive 16 75 8 0.28 78-88 188-195
Canola 7 54 37 2.8 110- 186-198
5.2 Antioxidant activity
120
Antioxidant capacity of coconut oil varies with the phenolic
SFA = Saturated fatty acid content; MUFA = Monounsaturated substances present in coconut oil. As the contents of
fatty acid content; PUFA = Polyunsaturated fatty acid content; phenolic substances and other antioxidants depend on the
Acid value; IV = Iodine value; SV = Saponification value method of extraction of coconut oil, antioxidant capacities
of coconut oils also vary with the extraction method. The
5.1 Antimicrobial activity antioxidant properties of virgin coconut oil produced
through chilling and fermentation have been investigated
and compared with those of refined, bleached and
Coconut oil contains lauric acid (50 %) which shows
deodorized (RBD) coconut oil. Virgin coconut oil showed
antiviral, antibacterial and antifungal properties. The more
better antioxidant capacity than RBD coconut oil. The
active substance against various bacteria and fungi is
virgin coconut oil produced through the fermentation

89 90
method had the strongest scavenging effect on 1,1- coconut oil, do not report the origin or method of extraction
diphenyl-2-picrylhydrazyl (DPPH) and the highest of coconut oil. As mentioned earlier, the fatty acid
antioxidant activity based on the -carotene-linoleate composition of coconut oil does not significantly vary with
bleaching method. However, virgin coconut oil obtained extraction method. However, due to the differences in non-
through the chilling method had the highest reducing power lipid components, coconut oil prepared by chilling coconut
(Marina et al., 2009). These antioxidant activities, which milk has a better beneficial effect in lowering lipid
correlated with the phenolic contents were lower in RBD parameters compared to copra oil. Lower levels of total
coconut oil. During the refining and bleaching steps natural cholesterol, triglycerides, phospholipids, LDL and VLDL
phenolic antioxidants are removed and antioxidant cholesterol levels and higher high-density lipoprotein
capacities decrease accordingly. (HDL) cholesterol levels were observed in rats fed with
virgin coconut oil compared to rats fed with copra oil
In another study, rats were fed with diets containing virgin (Nevin & Rajamohan, 2004).
coconut oil prepared by chilling coconut milk and copra oil.
After 45 days, antioxidant vitamin levels were higher in The effect of the degree of unsaturation of edible oils on
rats fed with virgin coconut oil. Low-density lipoprotein the tissue lipid levels in rats have been studied at different
(LDL) isolated from the rats fed with virgin coconut oil vitamin E levels (Mohamed et al., 2002). In this study,
was found to be more resistant to oxidation compared to menhaden, olive, and coconut oils have been used as the
LDL isolated from rats fed with copra oil or sunflower oil. lipids with different levels of unsaturation, considering
Virgin coconut oil also showed beneficial effect on blood coconut oil as the lipid with lowest degree of unsaturation.
coagulation. The lower levels of fibrin and fibrinogen in The results have shown that serum total cholesterol,
virgin coconut oil fed rats compared to copra oil fed rats triacylglycerol, HDL and phospholipids levels were
indicate that the blood clotting tendency decreased in virgin significantly lower in rats fed with menhaden or olive oil
coconut oil fed rats (Nevin & Rajamohan, 2008). Phenolic compared to the levels of these in rats fed with coconut oil.
fractions of virgin coconut oil prepared by chilling coconut The levels of vitamin E in the diet had a significant effect
milk and copra oil have been compared for their potential on serum cholesterol and liver phospholipids.
to inhibit Cu2+ induced in vitro LDL oxidation (Nevin &
Rajamohan, 2004). The results indicated that the phenolic The beneficial effects of virgin coconut oil extracted by wet
fraction of virgin coconut oil prepared by chilling coconut extraction by chilling coconut milk and by boiling coconut
milk has better potential to inhibit LDL oxidation compared milk have also been compared. The antioxidant activity of
to the phenolic fraction of copra oil as measured by the phenolic fraction of coconut oil prepared by boiling
carbonyl formation. Most of the studies on health effects of coconut milk, tested by DPPH radical scavenging assay

91 92
(Hatano et al., 1988) and deoxyribose degradation assay glutathione while it decreased lipid peroxidation in the liver
(Halliwell et al., 1987) is at least two times higher than that more effectively than coconut oil extracted by freezing the
of the phenolic fraction of coconut oil prepared by chilling coconut milk emulsion. The improved antioxidant
coconut milk. Serum Trolox equivalent antioxidant activity properties are due to the increased amounts of phenolic and
studies of the rats fed with special diets containing other antioxidants present in coconut oil extracted at high
traditional coconut oil prepared by boiling coconut milk temperatures from coconut milk emulsion. The results of
and coconut oil prepared by chilling coconut milk indicate these studies further proves that antioxidants present in
that traditional coconut oil improves the serum antioxidant coconut oil are stable at high temperatures and their
status more pronouncedly compared to coconut oil activities remain unaffected even at 120C. According to
prepared by chilling coconut milk (Seneviratne et al., this study, the total phenol contents of commercial copra
2009). These antioxidant activity studies indicate that most oil, cold extracted coconut oil and hot extracted coconut oil
of the antioxidant substances of coconut oil are stable at are 64, 75, and 242 g/g respectively. Some antioxidants
high temperatures. The polyunsaturated oils have a lower may inactivate or destroy at high temperatures. For
thermal stability in the saponifiable fraction due to various example, -tocopherol was destroyed during the processing
oxidation processes of fatty acids possible at high of raw corn and other selected foods (Wyatt et al., 1998).
temperatures. However, due to high saturated fat content of Hydroxytyrosol derivatives present in virgin olive oil were
coconut oil and due to the thermal stability of phenolic also destroyed due to thermal oxidation at high
substances in coconut oil, high temperature extraction of temperatures (Nissiotis & Margari, 2002). Even though
coconut oil appears to not cause any nutritional damage to high temperatures may destroy or inactivate certain
coconut oil. A later study also further verifies the findings phenolic compounds in coconut oil, the better incorporation
on the properties of traditional and cold extracted coconut of thermally stable phenolic substances during high
oils. In this study reported in 2011, coconut oil was temperature extractions may compensate for this loss.
prepared from coconut milk emulsion by cold and hot
extraction under similar conditions used by Seneviratne et The superoxide dismutase activity was increased by 31%
al. (2009) (Siddalingaswamy et al., 2011). The results of and 28% and catalase activity was increased by 37% and
this study indicated that coconut oil extracted by boiling 39%, respectively in rats given blends and interesterified
coconut milk at high temperatures (393 K, or 120C) oils of coconut oil/groundnut oil as compared to those
reduced blood glucose, total cholesterol, triglycerides, given coconut oil. The LDL oxidation, which was elevated
LDL, and very low density lipoprotein. This oil also by feeding ground nut oil, was found to be reduced by 10%
elevated activities of antioxidant enzymes such as and 14%, respectively, in the groups fed with blended and
superoxide dismutase, catalase, glutathione peroxidase, and interesterified oils of coconut oil/groundnut oil.

93 94
5.3 Coronary heart disease lauric acid (C 12:0) and palmitic acid (C16:0). Feeding
Sprague-Dawley rats with these synthetic triglycerides
Most of the data generated by scientists in this case are indicated that the excretion rate of 14CO2 as the end product
based on epidemiological studies and animal studies. of fatty acid metabolism decreases with the chain length of
There are several difficulties in conducting studies fatty acids. This observation is probably due to, at least in
involving human beings especially in the case of heart part, differences in the route of transport of the fatty acids
diseases. In such experiments, it is hard to keep several to the tissues following absorption from the gastrointestinal
factors constant in a human test group because, it is tract. The major fatty acid in coconut oil is lauric acid and
difficult to keep genetic factors, age factors, food other than percentage of the administered radioactivity recovered as
14
tested food, physical activities, metabolic rates etc. CO2 in the breath of rats after 48 hours was 69%
constant. Based on several evidence, Kaunitz et al., (1972) compared to 50% in longer chain palmitic acid (Kirschner
reported, “whether or not human societies consuming & Harris, 1961). These results indicate that shorter chain
large amounts of coconut oil develop more or less fatty acids oxidizes more easily instead of entering the fat
arteriosclerosis than other societies and whether any deposits compared to longer chain fatty acids.
differences are due to the fats consumed cannot be
answered with any degree of certainty.” Even after four As mentioned earlier, coconut oil contains a saponifiable
decades since then, the scientific findings are not strong fraction and an unsaponifiable fraction. If the nutritional
enough to dispute this statement. However, it is important quality of coconut oil is discussed, it is important to
to consider the up-to-date findings about coconut oil and consider the contribution of both fractions towards the
heart disease. nutritional quality. Of these two fractions, saponifiable
fraction is highly debated fraction when heart diseases are
It is common opinion that saturated fat is bad for health and considered. However, as shown in Table 14, coconut oil
it increases cholesterol levels in blood. However, when has a unique composition. The long chain saturated fatty
considering health effects of saturated fat, it is also acids that are present in animal foods and milk are known
important to consider the nature of saturated fatty acids. In to increase the cholesterol levels in blood. However,
this case, chain lengths of fatty acids are important, as the according to some reports, coconut oil neither increases nor
metabolic pathways of fatty acids depend on the chain decreases the serum cholesterol levels (Atukorala, 1996).
length of fatty acids. A study has been conducted with 14C These observations are based on the fatty acid composition
labeled synthetic triglycerides containing saturated fatty of coconut oil. In addition to fatty acid composition, it is
acids such as butyric acid (C 4:0), caprylic acid (C 10:0), also important to consider the effect of unsaponifiable
compounds on heart diseases and other health effects.

95 96
The structure of cholesterol is given Figure 11. Cholesterol important to consider the findings of several
is an essential biochemical for life. Cholesterol is present epidemiological studies and evidence collected from
in blood, liver brain and kidneys. It is essential for cell society, as well as evidence from laboratory studies.
function and human brain cells cannot function well,
without a certain level of cholesterol. It is also essential in CH3
the production of hormones. It is believed that only H3C
animals can produce cholesterol and plants contain little or CH3 CH3
no cholesterol. As indicated in the structure, cholesterol is
an alcohol. In the body, cholesterol may be present as free
cholesterol or as esters of fatty acids from the etherification CH3 H
of the alcohol group of cholesterol with the carboxylic
group of fatty acids. Cholesterol is transported within the H H
body in the blood plasma in two major forms of HO
lipoproteins; low density lipoprotein (LDL) and high
density lipoprotein (HDL). HDL is known as good
cholesterol. It is a cholesterol scavenging lipoprotein which Figure 11. Structure of cholesterol
takes up excess cholesterol and transport to liver for
catabolism. Those who have high levels of LDL in blood
are prone to heart attacks and those with higher levels of The uptake of cholesterol by cells of the arterial wall-
HDL are protected from heart attacks. monocytes/macrophages is mediated by a self-regulating
receptor that limits cholesterol deposition when the
Atherosclerosis is the gradual deposition of cholesterol and required intracellular levels are reached. A macrophagic
other fats inside the arteries causing the thickening of scavenger receptor which internalizes oxidized LDL is not
arterial walls. It is the primary cause of death worldwide. down-regulated by increasing intracellular cholesterol
The narrowing of the coronary arteries reduces the blood levels (Brown & Goldstein, 1983). This leads to the
flow to the heart muscle and result in a heart attack. hypothesis that oxidized LDLs play an important role in the
Elevated levels of circulating low-density lipoprotein occurrence of atherosclerotic lesions due to the uptake of
(LDL), which are rich in cholesterol and cholesterol esters, oxidized LDL by such receptor and the subsequent
are a well-established risk factor for developing coronary infiltration and deposition of cholesterol-laden cells (form
heart disease (CHD) (Ross, 1993). Before making any cells) into the arterial wall (Steinberg et al., 1989).
conclusions about coconut oil and heart diseases, it is Evidence of an in vivo presence of oxidized LDL, either

97 98
circulating or embedded in atherosclerotic plaques is (1996) has pointed out, based on the figures of the Central
increasing. Considerable evidence suggests that inhibition Bank of Sri Lanka, the coconut consumption has gone
of the oxidation of LDL may reduce the risk of heart down from 132 nuts per person per year in 1952 to 90 nuts
disease. Minor polar compounds of olive oil have shown in per person per year in 1991. However, the evidence of the
vitro protection of cholesterol LDL against oxidative stress heart attacks in Sri Lanka is increasing whereas the
(Berra et al., 1995). consumption of coconut is decreasing. And the present
epidemic of heart disease doesn’t appear to be due to
As mentioned in section 5.2, there are several phenolic increased consumption of coconut. One other interesting
substances present in coconut oil that are known to show study was conducted later by Prior et al. involving the
antioxidant properties. There is growing evidence from population of about 2500 people from two Polynesian
epidemiological and controlled studies that correlates a atolls, the Pukapuka and Toleku (Prior et al., 1981).
high intake of antioxidants with a lower incidence of CHD Coconut provided 35% of the energy of Pukapukans and 56
(Hertog et al., 1993). Studies conducted using animals % of the Tokeluans. The evidence of heart disease is very
indicate that fatty acids of coconut oil may offer protection low among these Polynesians even though the content of
from cardiovascular disease (Lemieux et al., 2011). This saturated fat consumed by Polynesians is 2-5 times higher
means that the composition of coconut oil containing high than the prescribed healthy levels.
amount of phenolic substances may actually reduce the risk
of heart disease instead of increasing the risk of CHD. In the studies involving large populations there are several
However, more evidence from in vivo studies is required to factors to be kept constant as described above to study the
prove this hypothesis. effect of consumption of coconut oil on the CHD.
However, factors such as genetic factors, physical activity,
Some evidence collected from studies involving large and nature of other lipids consumed cannot be uniform in
number of populations are discussed below. Early reports all the participants in these studies. Studies conducted
indicate that the inhabitants of the Thailand have a low rate using a group of young Sri Lankan adults have shown that
of heart attacks and strokes although coconut oil is their although coconut consumption has increased the total
leading dietary fat (Pollack, 1952). In a study on two cholesterol level, HDL was increased by 69 % while LDL
groups of Polynesians, it was found that Pukapukans by 32 % (Mendis, et al., 1989). Studies conducted over 50
consuming large amounts of coconut oil had lower serum years ago indicated that the intake of vegetable oil
cholesterol levels and a lower incidence of arteriosclerosis containing large amounts of linoleate reduced serum
than the Maorisan Europeans who consumed a large cholesterol levels in humans (Bronte-Stewart et al., 1956).
European type diet (Shorland et al., 1969). As Atukorala The subsequent feeding of the same formula diet with

99 100
coconut oil, raised the level of serum cholesterol although cholesterol levels of rats fed with 10 % oils and blends for
not to the levels previous to the intake of the linoleate rich 60 days were determined. Serum cholesterol levels were
diet. It was noted that the effect on the increment of serum lowered by 6% and 13% respectively, in rats given blended
cholesterol by coconut oil was less pronounced than oils containing coconut oil/groundnut oil and coconut
anticipated based on its saturation (Anderson et al., 1957). oil/olive oil in comparison with rats fed with coconut oil.
In two publications, a cross-sectional study of pre- and Serum cholesterol levels were found to be reduced by 27%
post-menopausal women, Feranil et al. (2011) found that a and 25%, respectively, when these blended oils were
high coconut oil intake related to high HDL in 1,121 subjected to interesterification reactions and fed to rats.
premenopausal women but not in the 718 post-menopausal The hepatic lipid peroxidation levels in the rats fed with
women. In the second publication, a brief, one-month study coconut oil/groundnut oil blend and interesterified oils
involving 20 obese people (13 females and 7 males) who increased by 31% and 21%, when compared to the rats fed
used virgin coconut oil, Liau et al. (2011) found an average with pure coconut oil (Nagaraju & Lokesh, 2008).
reduction of about 1 inch in the waistline of the 7 males However, discrepancies exist across publications.
with no change in anyone’s blood lipids.
5.4 Alzheimer’s disease
The studies involving pigs fed with fish oil, milk fat olive
oil, and coconut oil have shown that the serum total Alzheimer’s Disease is a common disease worldwide and it
cholesterol concentration was significantly higher in pigs is considered as a dementia. The disease is characterized by
fed with coconut oil. However, the pigs fed with coconut the decline of cerebral glucose metabolism. Brain cells
oil, olive oil and milk fat had a significantly higher HDL depend upon mitochondria which transform glucose into
cholesterol concentration than those fed with fish oil energy and this energy is required for brain functions.
(Frazer et al., 2001). This finding is in agreement with the
During Alzheimer’s disease, mitochondria become less
earlier findings that coconut oil may increase serum total
able to absorb and use glucose and this affects the glucose
cholesterol level such that HDL or good cholesterol levels
metabolism (Henderson et al., 2008). A number of animal
are increased more.
studies found that the intake of coconut oil led to
improvement in mental skills (Freeman et al., 2011;
In addition to pure coconut oil, coconut oil blends have also
Granholm et al., 2008). Medium chain triglycerides
been tested for various health effects. In this case, oils
(MCTs) directly go to liver and ketones are produced due
have been blended by mixing or by interesterification
to break down of MCTs. These ketones are transported to
reactions catalyzed by IM-60 lipase from
the brain through blood stream. When glucose metabolism
Rhizomucormiehei (Nagaraju & Lokesh, 2007). Serum

101 102
fails, these ketones can act as an alternate fuel or back up 5.5 Cancer
fuel. It is also believed that ketones may help restore and
renew neurons in the brain. Influence of ketones and their Dietary fats and fatty acids are considered as potential risk
precursor, MCTs on the cognitive effects has been factors in carcinogenesis, in particular colon cancer (Eder
suggested. An orally fed ketogenic compound AC-1202 has et al., 2006). However, it is not clear whether the type of
improved the cognitive performance in humans (Henderson fatty acids is an important factor. It is also not known
et al., 2009). Another study suggests that elevation of whether genotoxic or epigenetic aspects of the process of
plasma ketone body levels such as β-hydroxybutyrate carcinogenesis play a major role. For genotoxicity, lipid
through an oral dose of MCTs may help people with peroxidation products of polyunsaturated fatty acids are
probable Alzheimer’s disease function significantly better possible candidates (Willett et al., 1990). Oxidative stress
on paragraph recall due to improved cognitive functioning and lipid peroxidation are considered to play a major role in
in older adults with memory disorders (Reger et al., 2004). carcinogenesis mediated by nutrition (Ames & Gold,
As coconut oil is the major MCT oil, its contribution to 1991). DNA damage can occur from the lipid peroxidation
ketone formation thereby influencing cognitive products. The damaged DNA forms promutagenic
performance can be easily hypothesized. However, not exocyclic DNA adducts in the liver. Therefore, the
many direct studies have been conducted to evaluate the formation of DNA adducts such as 1, N6-
influence of coconut oil on Alzheimer’s disease (Doty, ethenodeoxyadenosine (etheno-dA), 3, N4 -
2012). The only other research related to coconut oil intake ethenodeoxycytidine (etheno-dC) and 1, N2 -
by people with Alzheimer’s disease or related dementias propandodeoxyguanosine from 4-hydroxy-2-nonenal
was the research on Axona®, a medical food which has (HNE-dGp) can be monitored as markers for DNA damage.
undergone several clinical, double-blind, placebo 8-Oxo-deoxyguanosine (8-Oxo-dG) can also be measured
controlled studies to determine safety and side effects, that as direct oxidative stress markers. The monitoring of these
contains some ingredients from coconut oil as well as markers of DNA damage in rats fed with sunflower,
several other ingredients on improvements on memory and rapeseed, olive, and coconut oil supplemented diets has
cognition in people diagnosed with Alzheimer’s disease shown that highest adduct levels of etheno-dC, HNE-dGp
and related disorders (Sharma et al., 2014). Therefore, more and 8-Oxo-dG were observed in rats fed with sunflower oil
studies are necessary to draw solid conclusions. supplemented diet. Highest levels of etheno-dA were found
in the rats fed with coconut oil diet. The results of this
study indicated that the oxidative DNA damage is high in

103 104
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Index Caproic acid 53, 55
Catechin 69, 71, 72, 73
Centrifugation process 11, 12, 40
Acid catalysis 83
Cholesterol 92, 93, 95, 96, 97, 98, 99, 100,
Acid value 15, 16, 18, 19, 20, 31, 32, 33,
101, 102
34, 46, 89
Coconut cake 44, 66, 75, 76
Aflatoxin 3, 49, 50
Coconut hybrids 45
Alcohols 30, 64, 86
Coconut milk 1, 10, 11, 12, 18, 31, 33, 35, 36,
Alzheimer’s Disease 102, 103
37, 43, 67, 91, 92, 93
Anisidine value 15, 30, 33, 51
Coconut oil blends 101
Anticancer properties 75
Codex Alimentarius 16, 41
Antimicrobial properties 75
Cold pressed virgin 39
Antioxidant properties 75, 90, 94, 99
coconut oil
Antioxidants 65, 90, 91, 94, 99
Colony forming units 36
Arachidic acid 53
Conjugated diene 24
Asian Pacific Coconut 16
hydroperoxide method
Community
Copra oil 1, 20, 25, 31, 31, 32, 34, 40, 41,
Atherosclerosis 97
42, 53, 57, 58, 61, 66, 69, 72,
Atomic absorption 60
79, 91, 92
spectrometry
Coronary heart disease 75, 97
Autooxidation 65
(CHD)
Ball copra 2, 47
Cup copra 2
Base catalysis 83
Deacidification 48
-Sitosterol 64
Degumming 48, 49
Biodiesel 81, 83 Desiccated coconut 4, 6, 14, 47
Boron trifluoride 56 DPPH radical 77
Caffeic acid 68, 69, 70, 71 scavenging activity
Campesterol 64, 79 Dry process 1, 32
Cancer 104 Endosperm 1, 2, 3, 44, 66, 68
Capric acid 53, 55 Enzyme assisted 13, 15, 36, 37
Caprilic acid 53, 55 extraction

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Epidemiological studies 95, 98 Medium chain fatty 29, 30, 53, 55, 88
Essential fatty acids 55, 58 acids
Esterification 56, 83 Metal content 60, 61
Extra virgin coconut oil 12 Moisture content 3, 4, 6, 36, 41
Fatty acid 34, 52, 52, 53, 56, 89 Moisturizer 85
Fermentation process 13, 35, 40, 43 Monolaurin 90
Ferulic acid 68, 69, 71, 72, 73 Myristic acid 53
Flavonoids 67, 72, 77 Oil blends 84, 101
Free fatty acid contents 20, 41, 45 Oleic acid 19, 53, 55
Gallic acid 43, 44, 65, 70, 71 Oleochemicals 86
Gas chromatography 40 Organic compounds 46, 64
(GC) O-diphenols 77
GC-MS 40 Oxidative rancidity 25
Glycerides 58, 59 PAH – polycyclic 46, 47, 48, 49
HDL 92, 97, 101 aromatic hydrocarbons
Health 1, 51, 75, 88, 101 Palmitic acid 53, 55, 96
Hexanal 30 Palmitoleic acid 53, 55
High performance liquid 68 P-coumaric acid 42, 68, 72, 73, 76
chromatography (HPLC) Peroxide value 15, 16, 17, 21, 23, 26, 30, 31,
Hydrocarbons 48, 64 32, 34, 40, 41, 60
Hydrolytic rancidity 4, 19 Pharmacological 75
Hydroxytyrosol 73, 77, 94 properties
Interesterification 101, 102 Phenolic acids 42, 67, 72
Iodine value 16, 17, 126, 27, 34, 41, 60, 89 Phenolic compounds 39, 42, 43, 65, 66, 67, 68, 69,
Kiln drying 4 72, 75
Lauric acid 19, 20, 37, 45, 55, 81, 89, 96 Phospholipids 48, 90, 92
LDL 91, 92, 94, 97, 98 Physico-chemical 35
Linoleic acid 21, 22, 53, 55, 56 parameters
Lubricants 80, 86 Polyphenols 30, 65
Mass spectroscopy (MS) 40, 72, 73 Promutagenic 104

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 Quality parameters 16, 31, 32, 34, 35, 40, 45, 51, Vanillic acid 73, 75
89 Virgin coconut oil 4, 7, 11, 12, 17, 25, 32, 35, 36,
RBD coconut oil 39, 40, 41, 90, 91 40, 41, 45, 69, 70, 85, 90, 91
Saponifiable fraction 51, 52, 60, 64, 96 Vitamin E content 39, 78
Saponification value 16, 17, 28, 29, 31, 33, 34, 51, VLDL 92
60, 89 Wet process 1, 10, 32, 35
Short chain fatty acids 19, 88
Solid phase 40
microextraction gas
chromatography
Solvent extraction 1, 8, 9, 87
Stearic acid 53, 55
Stigmasterol 64
Sun drying 2, 4, 57
Super critical carbon 9, 38, 39
dioxide
Testa 3, 4, 6, 16, 45, 65, 66
Thermogravimetric 24, 25
methods
Thiobarbaturic acid 24
Thiocyanate assay 22, 23
method
Tococpherols 36, 78
Total phenol content 42, 43, 44, 65, 67, 68, 70
Traditional coconut oil 11, 20, 26, 31, 34, 42, 55, 61,
66, 67, 69, 70, 71, 72, 93
Transesterification 81, 82, 83

Triglycerides 4, 10, 16, 18, 19, 27, 28, 42, 52,

56, 58, 59, 81, 86
Unsaponifiable fraction 31, 52, 60, 64

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