Chapter 12

Vegetable Oils and Fats: Extraction,

Composition and Applications

Zahia Ghouila, Moussa Sehailia and Smain Chemat

Abstract Lipids contain a broad category of non-polar molecules that are barely
soluble or completely insoluble in water, but soluble in chloroform, hexane, methanol
and diethyl ether. The main sources of edible lipids are from the agricultural origin,
mainly extracted from fruits, seeds or fish. They are found in the form of free or bound
fatty acids, phospholipids, waxes, sterols, tocopherols, carotenoids, cholesterol and
similar compounds. Oilseeds and fats production requires several unit operations,
starting with a pre-treatment stage that includes washing, drying, heating and flaking
followed by a processing stage, dependent on the type of raw material and the target
product, using different techniques alone or combined such as rendering, pressing
and solvent extraction. Crude fat and any other soluble material can be co-extracted
in addition to lipids. These may include residual moisture, pigments, carotenes, urea
and other compounds. The final stage concerns purification the obtained oils via
multiple operations which involve refining, bleaching, destearinating or winterizing,
hydrogenation and deodorization. In the last decade, oilseeds and fats have witnessed
the extension of their application range from edible food towards new applications.
Nowadays, they are included in many preparations of a large range of cosmetics,
functional ingredients or nutraceuticals and recently have made the breakthrough as
synthons and greener solvent options as described later in this chapter.

Keywords Edible oil · Fats · Extraction · Refining · Green solvents · Oilcake ·

Fatty acids · Olive oil · Sunflower oil · Rapessed oil

Z. Ghouila · M. Sehailia · S. Chemat (B)

Research Centre in Analytical Chemistry and Physics (C.R.A.P.C), BP 384 Zone Industrielle de
Bousmail (Ex. PASNA), Bousmail, Tipaza CP 42004, Algeria
e-mail: chemats@yahoo.fr

© Springer Nature Singapore Pte Ltd. 2019 339

Y. Li and F. Chemat (eds.), Plant Based “Green Chemistry 2.0”,
Green Chemistry and Sustainable Technology,
https://doi.org/10.1007/978-981-13-3810-6_12
340 Z. Ghouila et al.

12.1 Introduction

Global oilseeds production reached record levels of 207 MT in 2015 and expected
to continue its moderate expansion at a growth rate of 1.6% p.a. far less the last
decade’s growth of 3.5% p.a which keeps oilseed prices under pressure. Oilseeds
production from palm represented in 2015 more than 30% of total oilseeds + fats
production, while soybean oil reached 51 MT (25.1%) bumped by production in
the USA and South America followed by rapeseed oil (11.3%), sunflower oil (8%)
[1]. This is due to the growing demand for protein meal which favours soybeans
over other oilseeds. Due to saturation in per capita, food demand in many emerging
economies and reduced growth in biodiesel production from vegetable oils, prices
are projected to increase less than the assumed inflation rate according to OECD
outlook [2]. Vegetable oil includes the oil from crushing oilseeds (around 53%),
palm (36%), palm kernel, coconut and cottonseed.
Global production of meals/cakes in 2014/15 would expand strongly and could
increase by 9% to 160 million tonnes driven entirely by soy, with incremental world
soymeal output estimated at close to 11 million tonnes (expressed in protein equiv-
alent) [3]. Other meals are expected to shrink, except for a small rise in palm kernel
meal and stable cottonseed meal.
In developed countries, more than 40% of dietary fat comes from isolated fats and
oils, with 60% obtained from basic foods, whereas the dietary fat in less developed
countries is obtained from fruits, cereals, vegetables, dairy products and meats, and
relatively little is consumed in the form of isolated fat products. Most fruits and
vegetables have from 0.1 to 2% fat, with the exception of avocados and olives, which
are exceptional in their high-fat content. Cereals range from 1 to 7%, and nuts may
contain as much as 70% fat [4].
The main storage form of lipids in plants and animals is in the form of glycerol
backbone with three fatty acids (triglycerides) which include fats such as lard, short-
ening, butter and margarine (solid at room temperature) and oils such as olive oil,
peanut oil, soybean oil or sunflower oil (liquid at room temperature). Lipids tend to
be solid when these three fatty acids are mostly or all saturated, while it is in liquid
form when the fatty acids are mostly or all unsaturated. Above the proteins and lipids
present in seeds, the wall surrounding the cell is mainly composed of cellulose, hemi-
celluloses, lignin and pectin. They are bound with these primary metabolites such as
proteins and carbohydrates with van der Waals interactions, electrostatic, hydrogen
or covalent binding.
Due to the nature of the matrix, the processing methods are generally neither
specific to lipids, nor they ensure 100% recovery of the lipid material. In the case
of crude fat, diethyl ether or petroleum ether stands as favourite solvents as they are
relatively non-polar and extract most non-polar components (triacylglycerols, sterols
and tocopherols). However, they fail to extract polar lipids, such as glycolipids and
phospholipids.
Special conditions are required to store oilseeds’ raw material to avoid alterations
caused by insects or moulds and prevent or delay lipid oxidation, which is known to
12 Vegetable Oils and Fats: Extraction, Composition and Applications 341

be favoured by enzymes, temperature, humidity and oxygen. For instance, reduction

in the seeds’ humidity by means of dryers and storage in silos under controlled
atmosphere using adequate ventilation without oxygen are widely used techniques
to avoid such deterioration.

12.2 Conventional and Innovative Extraction Techniques

and Solvents

Before processing, oilseeds’ moisture must not exceed a certain limit to prevent the
growth of fungi and the occurring lipase formation, resulting in a free fatty acid
increase. In this case, conditioning the raw material is required which includes a
combination of drying with heating to induce the hulls surrounding the oilseed to
dry and shrink away from the meat part of the seed.
Generally, three processing methods are used to recover fats from oil-bearing
tissues: (1) rendering, (2) pressing with mechanical presses and (3) extracting with
volatile solvents [4].

12.2.1 Rendering

Fruits and seeds

Rendering oil from oleaginous fruits consists of heaping them in piles, exposing
them to the sun and collecting the oil that exudes. This process is still used in the
preparation of palm oil where the fresh palm fruits are boiled in water, and the oil is
skimmed from the surface. Such processes are only suitable for seeds or fruits (such
as olive and palm) containing large quantities of easily released fatty matter.

Animal fats
The rendering process is applied on a large scale to the production of animal fats
such as tallow, lard, bone fat and whale oil. It involves cutting or chopping the fatty
tissue into small pieces that are boiled in open vats or cooked in steam digesters. The
fat is then liberated gradually from the cells and floats to the surface of the water,
where it is collected by skimming. Additional fat is obtained from the separation of
the greaves from the aqueous layer by pressing using hydraulic or screw presses. The
residue is used for animal feed or as a fertilizer.
In parallel, centrifugal separation processes were developed to dislodge the protein
tissue from the liquid phase, followed by a second centrifuge separating the fat from
the aqueous protein layer. Compared with conventional rendering, the centrifugal
methods provide a higher yield of better-quality fat, and the separated protein has
great potential as an edible meat product.
342 Z. Ghouila et al.

12.2.2 Pressing Processes

In this process, the cell walls are broken by grinding, flaking, rolling or pressing
under high pressures to liberate the oil. Pressing oilseeds and nuts follows a general
sequence:
(1) Removal of any stray bits of metal from seeds using magnetic separators
(2) Removal of the shells or hulls, if necessary
(3) Conversion of the kernels or meats to a coarse meal by grinding them between
grooved rollers or with special types of hammer mills and
(4) Pressing using expeller, hydraulic or screw presses with or without preliminary
heating, depending on the type of oil-bearing seeds/fruits and the desired quality
specification of oil.
Oil expression without heating contains the least amount of impurities; thus, it
does not require refining or further processing. Such premium oils are known as
cold-drawn, cold-pressed or virgin oils [5].
Using heat during pressing, the coarse meal removes more oil, that is highly
coloured than cold-pressed oils, but accompanied with non-glyceride impurities
such as phospholipids, carotenoids and unsaponifiable matter. From the cooker, the
flack seeds are passed through the expeller, also known as screw press. This process
squeezes out about 70% of the oil, which is routed to a settling tank [5]. Residual
meals are concentrated sources of high-quality protein and are generally used in
animal feeds.

12.2.3 Solvent Extraction

Generally, crude oils are recovered by solvent from the meal comprising also proteins
and carbohydrates. During the solvent extraction process, the oilseeds are flaked due
to thermal stress which ruptures the cell wall and exposes the oil present inside the
cell to the bulk medium and facilitates percolation of the solvent through the matrix.
The solvent dissolves the oil, while the protein remains in the meal with the fibres
and carbohydrates. In the case of the aqueous extraction process of oil, the soluble
components diffuse into the water, and the partially soluble oil forms a separate liquid
phase or is partially emulsified with the water [4]. The properties of the oil such as
refractive index, density, saponification and free fatty acid values were affected by
the type of solvent used, and therefore, the selection of solvent is of high importance
to fulfil quality standards.

12.2.3.1 Conventional Extraction

Usually, the seeds undergo a cracking or grinding step before the conditioning pro-
cess described earlier. The temperature (30–40 °C) and moisture content (~8%) are
12 Vegetable Oils and Fats: Extraction, Composition and Applications 343

adjusted before the flaking process which is known as conditioning. After cooking,
the seed is passed for flaking and flatten to a thickness of ~0.25 mm [6]. This process
helps in the extraction process by rupturing the cells which enhanced the percolation
of the solvent. Various solvents have been used commercially to extract lipids from
oil-bearing material. Hexane and hexane-based solvents are broadly accepted as the
most efficient solvents for oil extraction despite concerns for its flammability, explo-
siveness, mild toxicity and environment impacts. The petroleum distillate containing
about two-thirds n-hexane is normally used in the commercial extraction of soybean
oil [7].
The modern solvent extraction process consists of percolating the solvent in a
successive countercurrent mechanism through the cracked, ground, flaked or pressed
oleaginous materials. Solvent is recovered from the oil by rising film evaporator
followed by vacuum distillation.
Extraction of oilseed involves several mechanisms for removing a liquid from a
solid including leaching, washing, diffusion and dialysis. Flaking helps in distortion
of the cells and rupture of cell wall. It also reduces particle size, thickness and the
distance required for transfer of oil into bulk materials. The transfer of oil from the
rupture cells is governed by capillary, and the rate of oil transfer is partially dependent
upon viscosities of solvent and micelle [8]. Little oil (less than 1%) is left within the
cake and is normally removed by osmosis. The solvent is separated from the meal
by distillation and recycled for the next process [6].
Lajara (1990) reported the importance of flake surface rather than the extent to
which cells have been opened during the flaking operation where heat treatment
causes extraction of more phosphatides [9]. During rapeseed dehulling, moistening
the seed with steam and drying the moistened seed in a fluidized bed resulted in
maximum dehulling efficiency [10].
Another process developed by Strop & Perry comprises an acid degumming treat-
ment step of the oil before it is forced to leave the oilseed [11]. In this case, the
resulting crude oil from milling is degummed with water and then treated with an
acid to decompose the non-hydratable phosphatides to obtain an oil quality of a low
phosphorus content that can be physically refined after bleaching [6]. In the Strop
& Perry process (1990), the mixture is heated under vacuum, causing some water
to evaporate, and the resulting slurry is then separated in a centrifuge to recover the
cooked oil. According to the invention, the cooked oil recovered from the centrifuge
only requires washing and filtering before being steam refined, cooled and stored.
This process allows oil refinery without a need for degumming, neutralization and
bleaching steps [11].
In the case of palm oil, crude oil is obtained after a digestion step followed by a
pressing stage. Digestion helps the rupture or breaking down of the oil-bearing cells
of the mesocarp, thus releasing the palm oil in the fruit. The digester consists of a
steam-heated cylindrical vessel at about 90 °C fitted with a central rotating shaft that
carries out a number of beater arms that is responsible to mash the fruits [12]. Then,
the mashed fruit is passed through a screw press to release the oil, and a residue called
the press cake is obtained which requires further processes to produce palm kernel.
Digestion at high temperature helps to reduce the viscosity of the oil, destroys the
344 Z. Ghouila et al.

fruits’ exocarp and completes the disruption of the oil cells. However, pressure has to
be optimized as high pressure will obviously cause undesirable higher nut breakage,
and thus, high broken kernel and subsequently higher kernel loss in encountered. In
addition, palm oil will be contaminated by the “kernel oil” [13].

Refining
Crude edible oil extracted from oleaginous commodities and marine catch often
require further downstream processing such as degumming, alkali refining, soap
removal, bleaching, filtration, fractionation, physical deacidification and deodoriza-
tion and crystallization. These operations help the removal of impurities and obtain-
ing uniform oil with good appearance and flavour quality and higher shelf life. At
the industrial scale, two broad refining categories are practised: chemical refining
and physical refining. The main difference between them resides in the removal of
free fatty acids (FFA) either by chemical addition or by physical removal through
distillation.
In case of the chemical or wet refining process, the impurities are removed by con-
tacting the oil with certain chemicals. It involves several stages including degumming,
deacidification, bleaching and deodorization. Crude oils usually possess a number of
desirable and undesirable compounds, while acylglycerols, tocopherols, carotenoids,
phytosterols and polyphenols are some of the essential components of oil [14]. Since
consumers expect bland and odourless oil with high oxidative stability, the refining
stages are designed to discard the major class of impurities that reduce the oil quality
like phospholipids, FFA, metal ions, oxidation products and other volatiles. In par-
allel, physical refining uses stripping with steam to remove under vacuum the FFA,
impurities and unsaponifiable matters from the oil.
Bleaching increases the taste of the oil by removing other pigments and residual
soap while other remaining off-flavours are removed during the deodorization step
by high vacuum (2–4 mmHg) distillation process in which oil is treated with steam
(2–4%) at high temperature (260–265 °C). To avoid the presence of waxes and fully
saturated triglycerides, winterization is performed by treating the deodorized oil to
a cooling period followed by filtration of the precipitate.
For crude palm oil, refining is necessary to separate palm oil (35–45%) from
water (45–55%) and fibrous materials [14]. It consists of pumping the crude oil into
a horizontal or vertical clarification tank. Then, steam is injected into the tank that is
maintained at around 90 °C to create an oil–water mixture which is left to settle for a
few hours. Upon settling, the clean oil undergoes centrifugation to discard impurities
and is subsequently passed through a vacuum drier to reduce moisture before it is
sent to the storage tanks.

12.2.3.2 Microwave Extraction

Microwaves have been proved to accelerate extraction rates of lipids from seeds and
tissue lipids. Using a laboratory microwave oven, maximal recoveries of glycerolipids
are reported to be similar to the classical Folch’s procedure [15]. Dielectric heating
12 Vegetable Oils and Fats: Extraction, Composition and Applications 345

(both high-frequency field and microwave field) has also been used for pre-treating
oilseeds using 2:1 (v/v) chloroform/methanol mixture instead of hexane in order to
extract the lipid fraction from the beans. The use of microwave irradiation to enrich
olive oil was also found to be effective under conditions of 0.1–5 W/g of oil and plant
material mixture [16]. Such approach could be exploited in a number of industries
to obtain special extracts in the form of scented extracts and other active ingredients.
Chiavaro et al. [17] indicated the oxidative deterioration under microwave power
of 720 W for 1.5–15 min of refined peanut, high-oleic sunflower and canola oil. It
was found that canola was more extensively oxidized by microwave heating. Both
peanuts and canola oil experienced changes in the heating profiles, free fatty acids
composition and peroxide value. Under microwave irradiation at 2450 MHz at vary-
ing power ranging from 3 kW to 5 kW, quality indicators of oilseeds (free fatty acids,
phospholipids as well as iodine and acid values) from soybean and rice bran showed
acceptable standards [18].

12.2.3.3 Ultrasound Extraction

A growing trend is registered for application of ultrasound in extraction of oils and

fats by enhancing rates, improving quality and/or safety and reducing processing
time. The benefits of ultrasound are attributed to acoustic cavitation: when a mixture
is subjected to ultrasound, micro-bubbles will grow and oscillate quickly before col-
lapsing due to pressure changes. These violent implosions are believed to fragment
or disrupt at the surface of the solid matrix, therefore enhancing mass transfer and
accelerating diffusion. Ultrasound-assisted extraction can be used during extraction
to enhance the enrichment of edible oils with carotenoids from pomaces. A combi-
nation of microwave and ultrasound was also found to maximize aromatization of
olive oil when mixed with vegetables, herbs, spices or fruits [16]. Notable are Sin-
caire et al. studies [19] that investigated ultrasound-assisted extraction for rapeseed
oil recovery where a multivariate study enabled them to obtain optimal parameters
(7.7 W/cm2 for ultrasonic power intensity, 40 °C for processing temperature and a
solid/liquid ratio of 1/15) in order to maximize lipid yield while reducing solvent
consumption and extraction time. Luque-Garc´ıa and Luque de Castro concluded
that the fatty acid composition of oilseeds such as soybean, sunflower and rapeseeds
is hardly affected by the application of ultrasound [20]. Using ultrasound to extract
flaxseed oil enabled to reduce processing time using an ultrasonic power: 50 W at
30 °C and a liquid-to-solid ratio of 6:1 (v/w) [21].
Several systems have been developed at an industrial scale, most of them used
for extraction of phytochemicals but also in aromatization of vegetable oils, i.e.
extraction of carotenoids and antioxidants from medicinal plants into edible oils.
Figure 12.1 shows an ultrasound-assisted system able to process up to 200 L in a
single run.
346 Z. Ghouila et al.

Fig. 12.1 200 L ultrasound-assisted extraction system (courtesy of Charles Gantz (REUS, France))

12.2.3.4 Green Solvent Options for Oilseeds Extraction

A solvent having low solubility at ambient temperature and high solubility at higher
temperature is desirable to profit from oil separation without evaporation. It should
be non-toxic to human and animal as well as safe for the environment. The solvent
should able to extract selectively only triglycerides leaving phosphates, free fatty
acids and pigments and should easily be recovered from the meal and oil. As far
as safety and environment issues are concerned, petroleum-derived solvents should
be replaced by greener options that are non-flammable or low flammable within a
narrow range of explosions such as azeotrope solvents, solvents based on aldehydes
and ketones, aqueous-based solvents and ionic solvents. In this case, solvents have to
be stable in heat, in light and in water while being able to withstand repeated cycles
of heating, vaporizing and cooling. They should be non-corrosive to equipment and
non-reactive with oil, meal and even with the equipment.

Azeotropic mixture
The alcohol/water mixture azeotropes of ethanol and isopropanol have been con-
sidered to be most commercially potential. As water content increases, the solvent
becomes more polar, and the solubility decreases towards oils, but capacity to extract
non-lipid substances (phosphatides, pigment and sugars) increases. Interestingly,
both the azeotropes of ethanol/water and isopropanol/water mixtures had shown to
12 Vegetable Oils and Fats: Extraction, Composition and Applications 347

be effective in removing the aflatoxins during the extraction [22]. Compared to the
absolute non-protic solvents, the protic organic solvents such as ethanol, methanol,
isopropanol and ethyl acetate, mixture of ethanol and ethyl acetate are found to have
more advantages in the oil extraction due to the presence of less organic impurities.
Azeotrope solvents show higher critical solution temperature and indicate better
extraction of oil from the seeds [23].
The loss of solvent is minimum in the azeotrope solvents because of the lower
boiling point of azeotrope compared to the pure solvent which reduces the cost of
extraction. The properties of the oil extracted by azeotrope solvent show less density
and refractive index value as compared to the n-hexane with fewer impurities.

Aldehydes and ketones

Aldehyde solvents, such as furfural (an aldehyde solvent) and furfural alcohol which
can be made from agricultural residues, have an excellent solubilizing property for
oils at warm temperatures, and the solvent is recovered from crude oil by either
chilling the miscella or adding water. Commercially, it is available. However, oils
extracted with furfural have high quantity of phosphatides [8].
Eaves et al. showed that acetone and butanone had the ability to extract oil from
cottonseed flakes which are similar to hexane. Although, free fatty acid is soluble
in acetone, phosphatides are insoluble. A process known as Vaccarino process was
developed to extract cottonseed meal with acetone commercially [24].

Aqueous oil extraction

The aqueous extraction process (AEP) uses water alone as an extracting medium in
which oil and protein (as a concentrate or an isolated form) can be recovered from the
oil-bearing material simultaneously. Extraction of oil by AEP is based on the insol-
ubility of the oil in water rather than the dissolution of oil [8]. During this process,
water-soluble components diffuse in the water which leads to the release of oil from
the previously bound structure, which can be enhanced by tuning pH, increasing tem-
perature or using enzymes to hydrolyze the cell walls [25]. In fact, mixing of ground
and dehulled oilseeds in the vats of hot water is done during which the oil rises on the
top of the surface and it is skimmed out [26]. In modern AEP, gravity separation is
replaced by centrifugation. Basic unit operations of AEP include grinding, solid–liq-
uid separation, centrifugation, demulsification and drying. Centrifugation separates
the oil from the bulk material so that protein and other materials are obtained as
concentrate in solid phase or isolates in aqueous phase depending upon the pH and
extracting media. Oil is recovered by breaking the emulsion, whereas the final pro-
teins can be obtained by isoelectric precipitation. The oil obtained after the demulsion
process has high quality and is required to remove the residual water for the final
refining step [27]. Membrane isolation process (MIP) and ultrafiltration (UF) can
be associated to recover the protein directly from the aqueous oilseed extract and
avoids the generation of whey. Reverse osmosis (RO) can be employed to recover
the secondary products and make the water reusable for the next cycle [27].
348 Z. Ghouila et al.

Supercritical CO2 (SC-CO2 )

Being non-flammable with relatively low toxicity, CO2 became the supercritical fluid
of choice because it is naturally abundant and hence inexpensive, and its critical tem-
perature is readily accessible (31 °C). Unfortunately, CO2 has low solubility for high
molecular weight and/or polar compounds, but strategies have been employed to
overcome its poor solvency power by the use of co-solvents (known as entrain-
ers) or surfactants and chelating agents. Edible oils contain non-polar characteristics
since they include a broad range of fatty acids, carotenoids, terpenoids, terpenes
and/or tocotrienols, making SC-CO2 suitable for their extraction from solid matri-
ces. Besides, CO2 is easily removable from the products by decompression at room
pressure, making the edible oils solvent-free. SC-CO2 was combined that alcohols
such as methanol (typically at levels less than 10 mol%) to improve CO2 ’s ability to
solvate polar solutes.
The application of CO2 in SFE of edible oils typically uses conditions ranging
from 40 to 80 °C and 20–50 MPa [28]. Density of CO2 can be tuned by changing
the system pressure or temperature, mainly in the region close to its critical pressure.
For example, in SFE-CO2 from olive husk, increasing pressure from 25 to 35 MPa at
constant temperature increased carotenoids concentration and decreased tocopherols
concentration in olive oil [29]. The low viscosity and the high diffusion coefficient
(10−3 cm2 s−1 ) favour obtaining high extraction rates when using supercritical fluids
as solvents. In fact, CO2 is a gas at 40 °C and 0.1 MPa with density of 2 kg m−3 ;
whereas it is in a liquid status at 27 °C and 50 MPa with density of 1029 kg m−3 ;
and at 40 °C and 10 MPa, it is a supercritical fluid with density of 632 kg m−3 and
viscosity as low as 17 μ Pa s, which is about 100-fold lower than that of liquids
permitting easier penetration and higher extraction rates [30].

12.3 Major and Minor Constituents of Fats and Oils

Edible fats and oils play significant role in diet, thanks to the energy intake provided
as needed by the human body. International authorities like World Health Organiza-
tion (WHO), Food and Agriculture Organization (FAO), the European Food Safety
Authority (EFSA) and many others recommend a total fat intake ranging from 20
to 35% of total calories [31–33]. This fat intake ensures an adequate consumption
of essential fatty acids and fat-soluble vitamins useful for the proper functioning of
the human body. The lowest level of high-density lipoprotein (HDL) of 20% is nec-
essary to prevent atherogenic dyslipidemia as a case of low high-density lipoprotein
cholesterol (HDL-C) and high triglyceride-rich lipoproteins [33]. The upper level
(35%) is to limit the saturated fat consumption leading to gain weight and increases
the risk of coronary heart disease [34, 35]. Edible fats and oils are composed of major
and minor constituents. The major constituents represented by the fatty acids family
comprises saturated, monounsaturated and polyunsaturated fatty acids (SFA, MUFA
and PUFA, respectively) depending upon the presence or absence of double bonds.
These are commonly called triglycerides and reach around 96% of total fatty acids
12 Vegetable Oils and Fats: Extraction, Composition and Applications 349

[36]. Free fatty acids (FFA), monoacylglycerols, diacylglycerols, phospholipids, free

and esterified phytosterols, polyphenols, triterpene alcohols, tocopherols, pigments
(carotene, chlorophylls), squalene and trace metal ions (e.g. iron, sulphur or copper)
are considered as minor constituents [37].

12.3.1 Major Constituents

12.3.1.1 Saturated Fatty Acids (SFA)

Saturated fatty acids, relative to compounds with only single carbon-to-carbon bonds,
are principally found under solid form in animal fats at ambient temperature. They are
relatively present in high amounts in many meats and dairy products, including whole
milk, cheese, butter and cream. They can also be found in coconut and palm kernel
oils, which contain more saturated fatty acids than lard, beef tallow and butterfat [38].
Among the SFA, lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0)
and stearic acid (C18:0) are the most abundant compounds in both fats and oils.
Lauric acid less abundant in animal fats and only present in butterfat with 3% of
total fatty acids reached high percentages in coconut and palm kernel oil (47% and
48% of total fatty acids, respectively) [39]. Similarly, myristic acid (C14:0) which
is a characteristic compound of animal fats can also be found at significant levels
in coconut and palm kernel oil. SFA with shorter carbon chain (less than C10:0) is
a characteristic of fats (butter) but can be found at trace levels in certain oils like
coconut, palm kernel and Indian ghee oils [39–41]. The palmitic acid (C16:0) and
stearic acid (C18:0) are the most abundant SFA and are omnipresent in the majority
of fats and oils at variable level, and the important level is reached by palmitic acid
(40–47% of total fatty acids) in palm oil [39, 42]. Arachidic (eicosenoic) acid (C20:0)
has been found at trace level (<1% of total fatty acids) in conventional oils such as
safflower (0.17–0.2%), canola (0.2–1.2%) and soybean (0.1–0.6%) oils [39], whereas
it reached high amounts in mustard oil (5.48 ± 0.36%) from India and pracaxi oil
(12.3 ± 0.12%) [41]. The same observation is noted for behinic acid (C22:0) rarely
present in common oils, and if it is present, it does not exceed 1% of total fatty
acids. The exception is the pracaxi oil which recorded an important level of 22.6 ±
0.0% of total fatty acids [43]. The presence of SFA at high amount in certain fats
and oils was appreciable especially by dietary industry for its resistance to oxidative
reactions, property which makes stability to the food products. However, the SFA
consumption was not advising since it was responsible for LDL-cholesterol-raising
potential causes of cardiovascular disease. Many health authorities suggest keeping
saturated fat intake as low as possible (<10% of total fatty acids) [44].
350 Z. Ghouila et al.

12.3.1.2 Monounsaturated Fatty Acids (MUFA)

Oleic acid (C18:1) is the most important of MUFA, and it is an acid with double
carbon-to-carbon bonds found at high level in almost fats and oils except for butterfat,
coconut and palm kernel oil which are rich in SFA. Oleic acid level ranging from 5
to 55% of total fatty acids is a characteristic of vegetable oils as for olive oils with
the highest level of 55%. Palmitoleic acid (C16:1) is found at low level (<3% of total
fatty acids) in olive oils when the majority of vegetable oils have none. Contrary to
the SFA, oleic acid reduces effectively at lowest total serum cholesterol and LDL-C
levels, and oils rich in oleic acid are advised in feeding diet [45].

12.3.1.3 Polyunsaturated Fatty Acids (PUFAs)

PUFAs are acids with more than one double carbon-to-carbon bonds. Two important
compounds are present in fats and oils, linoleic (C18:2) and linolenic (C18:3) acid
known as omega 6 and omega 3, respectively. These acids not synthesized by the
body are vital for its functionality. The intake needed was provided by the fats and
oils diet. Oils contain high level of linoleic acid ranging from 1 to 48% of total
fatty acids, while lower levels not exceeding 1% are contained by fats [39]. High
amounts of omega 6 have been recorded for safflower (76.58%), sunflower (62.69%)
and soybean (54.17%) oils [46]. Certain usual vegetable oils like olive oil rich in
oleic acid registered level of linoleic acid ranging from 3.5 to 21.0% of total fatty
acids. Others oils, especially Amazonian oils which high level of oleic acid of 65.9
± 0.45%, have been reached in passion fruit oil, and their fats also contain more
important level than common fats as for cupuassu fat (5.2 ± 0.0% of total fatty
acids) [43]. The omega 6 is also found in oils newly introduced in food such as
grape seed oil which contains between 58 and 78% of total fatty acids. Belonging to
omega 3 fatty acid class, linolenic (C18:3) or α-linolenic acid (ALA) is considered
as essential because it cannot be synthesized by human organism and believed to
be precursor of others omega 3 like EPA and DHA. Plants are important sources of
such ALA but can also be found in fats, exceptionally in butter and margarine made
from vegetable oils. For animal fats, around 0.98–1.2% of total fatty acids have been
recorded in butter and lard, and higher level has been registered for vegetable fats such
as margarine with 2.4% [47]. However, it has been found beyond these concentrations
in no common fats like cupuassu fat in which omega 3 reached 11.5 ± 0.45% of total
fatty acids [43]. The intake in omega 3 from vegetable oils widely consumed in our
diet varies between less than 1 and 14% of total fatty acids such as olive, safflower
and sunflower oils (<1%), soybean (4.5–11.0%) and canola (5.0–14.0%) oils [39].
The highest levels of omega 3 have been found in oil from oilseed, with level up to
50% of fatty acids, as in the case of linseed oil ranging from 54 to 71% of total fatty
acids [47].
12 Vegetable Oils and Fats: Extraction, Composition and Applications 351

12.3.2 Minor Constituents

12.3.2.1 Monoacylglycerols (MAGs) and Diacylglycerols (DAGs)

Mono- and diglycerides are mono- and diesters of fatty acids and glycerol, frequently
used as emulsifiers in food industry. They are naturally formed in the intestinal tract
as a result of the normal digestion of triglycerides and commercially prepared by
the esterification of glycerol and fatty acids or by simple reaction of glycerol and
triglycerides. They are the major components of the food additive E471 which can
be of animal or vegetal origin [48]. The amounts of MAGs and DAGs in vegetable
oils vary in the range of 3.0–7.6% as reported by O’Brien et al. [48].
Catalano et al. established the remarkable differences in total DAGs, i.e. 1,2(2,3)-
and 1,3-diacylglycerols as characteristic parameters of virgin olive oil quality [49].
In extra virgin oils, the total DAGs were less than 2.0, 97.7% of the oils had less
than 1.5% of 1,2 DAG and less than 0.4% of 1,3 DAG. Should there be a need to
know the quality of the oil of origin, it may be more appropriate to include the DAG
content as a complementary parameter. Generally, freshly extracted oils have a low
DAG content of 2.3–4%. However, the conditions prevailing in the industry such as
harvesting conditions, transportation of fruits to factories result in commercial oils
having DAG contents of 4.0–7.5%.

12.3.2.2 Phosphatides or Phospholipids

Phosphatides are present at trace level (0.1–3%) in crude oils. They are derived from
the association of glycerol with fatty acids and a phosphate ester and are composed
essentially by phosphatidylethanolamines, phosphatidylinositides and other phos-
pholipids. Soybean oil, rapeseed oil and sunflower oil are the main sources. They
are used as emulsifiers in food industry under the name of lecithin formed only of
phosphatidylcholines which is present in high quantity in sunflower and soybean oil
(52% and 30% of total phosphatides, respectively) [50]. Adding also their property
as an antioxidant often highlighted in many oils [51]. The majority of phosphatides
naturally present in oils are removed from oil during the degumming and refining
processes which are recovered and treated to yield a variety of lecithin products.
Among the oils with important level of phosphatides, soybean oil is at the top of the
list with 2.2 ± 1.0%, followed by canola oil with 2.0 ± 1.0%, corn oil (25 ± 0.25%),
cottonseed oil (0.8 ± 0.1%), sunflower oil (0.7 ± 0.2%) and safflower oil (0.5 ±
0.1%). Olive oil and other commons oils contain less than 0.1% of phosphatides
[48].
352 Z. Ghouila et al.

12.3.2.3 Sterols

Sterols are found in both animal fats and vegetable oils. The cholesterol is the animal
fat forms as for butter which can contain about 215 mg/100 g. This kind of sterols
is rarely found in vegetable fats and oils. Phytosterols, the current form found in
vegetable fats and oils, can be found free or esterified with other molecules such
as fatty acids. The profile of phytosterols allows to detect oil adulteration or to
identify the oils and fats in a mixture. The most common concentrations found in
vegetable oils are of the order of 1000–5000 mg/Kg. Different types of phytosterols
are present in oils as for brassicasterol, campesterol, stigmasterol and β-sitosterol,
and campesterol and β-sitosterol are the most abundant and found in the major of
oils at high concentrations as for canola oil (1904.4 and 3608.7 mg/Kg), soybean
oil (1191.40 and 2060.80 mg/Kg) and sunflower oil (266.50 and 2300.10 mg/Kg).
Brassicasterol stands as a characteristic parameter of canola oil with level of 14.3%
of total phytosterols reaching a concentration of 986.70 mg/Kg (Table 12.1). Corn
oil has recorded 15,050 mg/Kg of sterols and its concentration can vary between
8000 and 22,000 mg/Kg, while olive oil is considered as the least rich in sterols with
100 mg/Kg [48].

12.3.2.4 Tocopherols/Tocotrienols

The tocopherols and tocotrienols are important minor constituents of most vegetable
fats and oils. They are recognized as natural fat-soluble antioxidants which permit to
retard rancidity. The common types of tocopherols and tocotrienols are alpha (α), beta
(β), gamma (γ) and delta (δ), depending on the number and position of methyl groups
on a chromanol ring. They are also an excellent source of vitamin E. Alpha-tocopherol
has the highest vitamin E activity and the lowest antioxidant activity compared to
the others tocopherols and considered as a standard (100%) for vitamin E activity.
Nutritionally, α-tocopherol used as additive (E 307) is subjected to health recom-
mendations with daily intake between 0 and 2 mg/Kg of body mass/day. Vegetable
oils recorded concentrations of total tocopherols ranging from 50 to 3500 mg/Kg.
Canola and sunflower oils contain, respectively, 566 mg/Kg and 898.8 mg/Kg of
tocopherols, while the highest concentration of 1146.4 mg/Kg has been recorded in
soybean oil (Table 12.1). Others oils with higher concentrations have been regis-
tered in corn and wheat germ oil with concentration range of 1100–1850 mg/Kg and
3000–3500 mg/Kg, respectively [53]. Tocotrienols rarely present in conventional oils
are found in palm oil in concentration range of 300–1000 mg/Kg.

12.3.2.5 Pigments

Carotenoids and chlorophyll are the most important pigments which can be found in
vegetable oils. The carotenoids as for carotenes, lycopene, xanthophylls and lutein are
considered as precursors of vitamin A (retinol) and are present in important quantity
12 Vegetable Oils and Fats: Extraction, Composition and Applications 353

Table 12.1 Minor Oils

compounds in canola,
soybean and sunflower oils Canola Soybean Sunflower
(adapted from Gordon et al. Phosphatides (%) 2.0 ± 1.0 2.2 ± 1.0 0.7 ± 0.2
[52])
Sterols (%)
Cholesterol 0.65 0.96 0.74
Phytosterol
Brassicasterol 14.3 Trace Trace
Campesterol 27.6 25.9 6.5
Stigmasterol 0 16.8 7.8
β-Sitosterol 52.3 44.8 56.1
5 -Avenasterol 2.5 6.5 14.8
7 -Avenasterol 0.9 2.8 5.9
7 -Stigmasterol 2.3 1.4 7.1
Total phytosterol 6900 4600 4100
(mg/Kg)
Esterified sterols 4231 576 2069
(mg/Kg)
Tocopherol (mg/Kg)
α-Tocopherol 197 179.3 206.5
β-Tocopherol – – –
U-Tocopherol 369 636.8 239
δ-Tocopherol – 330.3 453.3
Total Tocopherols 566 1146.4 898.8

in palm oil in range of (1000–2000 mg/Kg). Among the palm oil carotenoids, α,
β, γ, δ, ζ carotene are present, respectively, in amount of 2519, 379.9, 2, 5.4 and
4.7 mg/Kg as well as lycopene with 8.7 mg/Kg [49]. Xanthophylls represent 90%
of total carotenoid concentration (117 mg/Kg) in crude oil followed by 10% of
carotenes (13 mg/Kg) [29]. Chlorophylls are the green pigments found in almost
vegetable oils, and they act on photosynthesis of plants. Chlorophylls are at the
origin of the green tinge of the oils which sometimes at important levels the oils are
denatured, and during oil process (refining) these levels are drastically reduced to
ppb levels. Among common vegetable oils, crude canola oil registered the highest
amount of chlorophylls range in 4–30 mg/Kg as well as crude olive oil (1–20 mg/Kg)
[29]. This latter concentration can exceed 80 mg/Kg for oil obtained from olives in
early maturity stage to finally reach 2 mg/Kg when the fruit is ripe [29].
354 Z. Ghouila et al.

12.3.2.6 Polyphenols

Vegetable oils like crude canola oil have a high amount of polyphenols (about 130 mg
gallic acid/Kg oil) which provide antioxidation and stability properties [54]. During
degumming and traditional neutralization steps, polyphenol percentage decreases
dramatically to 2.1 mg gallic acid/Kg oil. Vinylsyringol, sinapic acid and sinapine are
the most important polyphenols found in canola oils [55]. Others phenolic compounds
in olive oil as for o- and p-coumaric, cinnamic, caffeic, ferulic, gallic, synaptic and
chlorogenic acids have been identified.

12.4 Examples of Fat and Oils

12.4.1 Olive Oil

Olive oil is extracted from olive fruit (Olea europaea L.) by several extraction pro-
cesses. These fruits with different shapes, sizes (e.g. 2–3 cm width and length) and
pulp per stone ratios (3.0–6.5) contain between 36 and 53% water (w/w), whereas
oil ranges between 18 and 27%. The last 20% are attributed to phenols, dietary fibre
(DF), free sugars, nitrogenous compounds and minerals [16]. In attempt to protect
the olive growing sector, the International Olive Oil Council (IOC) has promulgated
four definitions for olive oil [6]:
1. Virgin olive oil: the oil from the fruit of the olive tree obtained by mechanical or
other physical means under conditions, particularly thermal, which do not lead
to alteration of the oil. Virgin olive oil is suitable for consumption as is and can
be designated as “natural” is further defined as:

(a) Extra virgin olive oil—oil that has a flavour rating of 6.5 or better and a 1.0
max free acidity.
(b) Fine virgin olive oil—oil that has a flavour rating of 5.5 or better and a 1.5
max free acidity.
(c) Semifine virgin olive oil—oil that has a flavour rating of 3.5 or more and a
3.3 max free acidity.

2. Virgin olive oil with an organoleptic rating of less than 3.5 or a 3.3 g/100 g free
fatty acid is considered not fit for human consumption. It is used to produce
refined olive oil or for non-food uses.
3. Refined olive oil is the oil obtained from virgin olive oil by refining methods
which do not lead to alterations in the initial triglyceride structure.
4. Olive oil can consist of a blend of refined olive oil and virgin olive oil in various
proportions.
12 Vegetable Oils and Fats: Extraction, Composition and Applications 355

To further improve extra virgin olive oil stability during storage, inert gases (such
as nitrogen or argon) were used as conditioner gas in the head-space of the container,
to test their ability to remove oxygen and prevent oxidation [56].

12.4.1.1 Production and Localization

The worldwide production of olive oil has considerably increased; it has risen from
1032 MT in 1958/1959 to around 3 MT in 2009/2010, then to 3.4 MT in 2011/2012.
This production represents approximately 3% of the world’s output of vegetable
fats and oils. Expansion in olive orchard plantings around the world has increased
gradually, and it rises from 4 Mha of land to 9.5 Mha in only six years with production
range in 9–15 MT of olive fruit [1, 2]. The major production part is localized in
Southern Europe, North Africa and the Middle East with 95% of the world’s olive
oil. Europe alone represents more than 67.31% of the world production. According
to the latest letter of IOC, world production of olive oil for the 2017/18 season
is estimated at 2,894,000 T with 14% higher than the previous season [57]. Spain
remains in the lead with an estimated output of 1,090,500 T, followed by Italy with
320,000 T, Greece with 300,000 T and Portugal with 78,800 T. The main increases
occurred in Turkey with 287,000 T (+62%), followed by Tunisia with production
of 220 000 T (+120%), Morocco with 140,000 T (+27%), Algeria with 80,000 T
(+27%), Argentina with 37,500 T (+74%) [57].

12.4.1.2 Extraction Process

Before oil extraction, olive receipt follows four steps in order to preserve olive oil
quality, (1) olive storage; (2) removing foreigner bodies; (3) washing, then (4) pro-
cessing.
Olive oil is generally obtained from olive fruit by mechanical procedures, which
involves one of the following extraction processes:
(i) discontinuous process in traditional mills (press olive oil extraction),
(ii) three-phase centrifugal olive oil extraction,
(iii) two-phase centrifugal olive oil extraction.
Extraction starts with the crushing step which aims at the release of oil droplets
from the cells of olive flesh. This operation is performed by metallic crushers, such
as mobile or fixed hammers, toothed discs, cones, cylindrical or rollers crushers.
Functioning at high-speed rotations, these crushers project violently the olives against
a fixed or mobile metal grating, which produces an olive paste. It is important to note
that metal crushers’ type as well as the crushing intensity affects the size of the stone
fragments, the extraction yields and the organoleptic properties of virgin olive oil
(VOO). In fact, metal or granite crushers influenced the organoleptic characteristics
of VOO, with higher content of total phenols (435 mg/Kg), have been obtained with
metal (hammer) crushers than granite (millstones) crushers (186 mg/Kg), and the
356 Z. Ghouila et al.

oil is more stable with a more bitter taste [58]. Over time the crushers have evolved
considerably, and crushers with new metallic crusher at mobile knives, crushers with
granite stone mill and with double olive crushing are nowadays frequency used.
The crushing step is followed by a malaxation phase where a slow stirring of
olive paste takes place to obtain larger drops by promoting contact between oil
droplets. These larger drops are separated in a continuous oily phase, thus avoiding
the formation of emulsions which affects extraction yield [6]. During malaxation, the
olive paste is heated by hot water in which addition of water enables paste dilution.
Generally, the malaxation phase is performed under certain conditions: (1) limited
mixing time 20–30 min, (2) temperature of the paste should not exceed 22–25 °C and
(3) paste/water ratio has to be kept between 1:0.4 and 1:0.7. The mixers automatically
spread the olive paste onto mats (filtering diaphragms of nylon fibre), which are then
stacked for pressing.
After that, there is a choice of three procedures to recover oil from the paste
using: hydraulic press, continuous centrifuges or adhesion filtering. Hydraulic press
applies high pressure to the paste placed between two metallic discs of trolley with a
perforation in central spike which permits the must (mixture olive oil + vegetation +
water) to flow. The oily must is then sent to a vertical centrifuge, rotating at 6500 rpm,
to separate the VOO from the aqueous phase (vegetation water) [46, 56].
Three fractions are separated from the olive paste: (1) oil, (2) wastewater and
(3) husks or residue. The husks are dried, and the remaining oil extracted with
solvent; therefore, two oil types are obtained from olives: (1) olive oil, which is
pressed without further processing (other than washing, decantation, centrifugation
and filtration) and contains less than 3.5% FFA; and (2) pomace oil, which is obtained
by solvent extraction of the husks and does not qualify as olive oil.

12.4.2 Palm Oil

The oil palm tree has the appearance of a date palm with a large head of pinnate
feathery fronds growing from a sturdy trunk. The most important palm species are
Elaeis guineensis from Africa and E. melanococca from America. The fruit grows
in bunches weighing 10–50 kg and each containing 800–2000 individual fruits. The
fruit consists of an outer pulp, which is the source of the crude palm oil; an inner
shell, which is used for fuel; and two or three kernels, which are the source of another
oil type: palm kernel [59]. Palm plant grows under specific conditions as for land
below 400 m attitude, moisture more than 80%, moderate temperature between 22
and 33 °C, adequate light not less than 5–6 h daily sunshine and solar radiation
of 16–17 MJ/m2 per day, high annual rainfall between 2500 and 4000 mm and for
low wind speed. The most oil palm commercialized is from E. guineensis species
which has spread to most parts of the tropical and subtropical zones of the world but
particularly Malaysia and Indonesia [60].
12 Vegetable Oils and Fats: Extraction, Composition and Applications 357

12.4.2.1 Production and Localization

Oil palm represented 34% of vegetable oils production with 54.385 mill tonne [1,
3]. Palm Oil has the highest oil yield crop with productivity between 4 and 5 met-
ric tonne per hectare [61] on top of the favourable climate conditions and to their
highly supportive governmental policy to support long-term strategic planning and
sustainable growth for palm oil industry, and Malaysia and Indonesia are the main
producers with more 90% of world palm oil production [2, 3]. The rest of world
production (10%) is shared with countries like Thaïland (3.6%), Nigeria (1.8%) and
Colombia (1.7%).

12.4.2.2 Chemical Composition of Palm Oil

Palm oil has specific fatty acid composition with equal portions of saturated and
unsaturated fatty acids and a significant amount of the saturated fatty acids (10–16%)
in sn-2 position of triglycerides. Palm oil is semisolid at room temperature with
high amounts of triglycerides, palmitic and oleic fatty acids [62]. Crude palm oil
contains high-carotene amounts range from 500 to 700 ppm due essentially to a
deep orange-red colour, of which 90% consists of alpha- and beta-carotene, and this
latter act as prooxidant which affects palm oil stability. The presence of tocotrienols
and tocopherols in the range of 600–1000 ppm gives to palm oil high antioxidant
protection [60]. Red palm oil is utilized as a natural colourant for margarine and
shortening products.
Others forms of palm oil as for crude, olein (fractionated oil) and stearin forms
present globally the same physical characteristics except for iodine value, and olein
products have iodine value within a relatively narrow range (56–58), but the stearin
fractions exhibit a wide range (25–49). For palm stearin, softening point ranges from
56 to 53 °C for the detergent process, 51–50 °C for the slow-dry process and 49°–46°
for the fast-dry process.
Currently, palm oil is widely used in food preparation and manufacturing world-
wide. Almost 90% of palm oil production goes for edible consumption, while the
remaining 10% of palm oil and its products are used for non-edible applications,
mainly in the soap and oleochemical industries [60]. The physical characteristics
and oil composition are summarized in Table 12.2.

12.5 Fats and Oils as Solvents

On top of the environmental impact, the utilization of volatile organic compounds

(VOCs) to affect chemical reactions and/or extract natural products from plants is
sparking an outcry because of their associated health, e.g. irritation, headaches, loss of
coordination and nausea. To respond to this challenge, scientists were able to exploit
a number of alternatives to the utilization of VOCs such as ionic liquids, supercritical
358 Z. Ghouila et al.

Table 12.2 Palm oil Parameter Typical Range

composition and physical
characteristics [48] Specific gravity 50 °C – 0.888–0.889
Refractive index, 50 °C – 1.455–1.456
Iodine value 53.0 46.0–56.0
Saponification number 196 190–202
Unsaponifiable number 0.5 0.15–0.99
Titer (°C) 46.3 40.7–49.0
Melting point (°C) (MDP) 37.5 35.5–45.0
Solidification point (°C) – 35.0–42.0
Cloud point (°C) −5.6 –
Cold test (hours) None –
Carotene content (ppm) – 500–700
AOM stability (hours) 54.0 53–60
Tocopherol content (ppm)
α-Tocopherol 172 129–215
β-Tocopherol 30 22–37
γ-Tocopherol 26 19–39
ζ-Tocopherol 13 10–16
Tocotrienol content (ppm)
α-Tocotrienol 59 44–73
β-Tocotrienol 59 44–70
γ-Tocotrienol 350 262–437
ζ-Tocotrienol 94 70–117
Fatty acid composition (%)
Lauric (C-12:0) 0.2 0.1–1.0
Myristic (C-14:0) 1.1 0.9–1.5
Palmitic (C-16:0) 44.0 41.8–46.8
Palmitoleic (C-16:1) 0.12 0.1–0.3
Stearic (C-18:0) 4.5 4.5–5.1
Oleic (C-18:1) 39.2 37.3–40.8
Linoleic (C-18:2) 10.1 9.1–11.0
Linolenic (C-18:3) 0.4 0.4–0.6
Arachidi (C-20.0) 0.4 0.2–0.7
Triglyceride composition (%)
Trisaturated (GS3) 10.2 4.0–10.5
Disaturated (GS2U) 48.0 41.0–59.0
Monosaturated (GSU2) 34.6 32.0–54.0
Triunsaturated (GU3) 6.8 3.0–12.0
Hydrogenated crystal habit β –
(continued)
12 Vegetable Oils and Fats: Extraction, Composition and Applications 359

Table 12.2 (continued) Parameter Typical Range

Solid fat index (%) at
10.0 °C 34.5 30.0–39.0
21.1 °C 14.0 11.5–17.0
26.7 °C 11.0 8.0–14.0
33.3 °C 7.4 4.0–11.0
40.0 °C 5.6 2.5–9.0
G—glycerides; S—saturated; U—unsaturated; AOM—active
oxygen method, MDF—Mettler dropping point

Fig. 12.2 Synthesis of biodiesel and by-product glycerol

fluids and other bio-derived solvents (e.g. 2-MeTHF). Most importantly, the choice
of non-VOC solvents in chemical reactions and/or natural product extraction not only
relies on the principle of eliminating the health hazard factor posed by VOCs but also
needs to respond to a number of green engineering criteria which are necessary to
protect our environment and promote growth and sustainability within the chemical
industry. For this reason, solvents derived from bio-based fats and oils are seen as
potential substitutes.

12.5.1 Solvents in Chemical Reactions

One of the most commonly exploited bio-derived oils used as solvent in chemical
reactions is glycerol. The latter is readily accessible from naturally occurring triglyc-
erides via base catalysed trans-esterification reaction in the presence of an alcohol,
e.g. methanol. In addition to glycerol, the process is primarily used with the prime
objective of making biodiesel (Fig. 12.2) [63, 64].
Given the eco-benign and sustainable source of glycerol, this compound was
widely examined as solvent to affect number of metal and non-metal catalysed reac-
tions.
360 Z. Ghouila et al.

12.5.1.1 Non-metal-Based Catalytic Reactions

A number of pharmaceutically important reactions were successfully synthesized

using glycerol as solvent. In this regard, various condensation reactions, nucle-
ophilic additions, electrophilic aromatic substitutions, cycloaddition reactions, Peta-
sis borono–Mannich, Friedel–Crafts alkylations and other multicomponent reactions
were successfully achieved using glycerol as solvent. Table 12.3 shows some liter-
ature examples where glycerol was used as an efficient solvent for certain type of
non-metal catalysed chemical transformations.

12.5.1.2 Metal-Based Catalytic Reactions

Given the importance of metal catalysed reactions in the synthesis of various phar-
maceutically important molecules, glycerol was successfully employed as solvent in
a number of reactions involving catalysts containing Cu, Zn, Al, Ni, Pd, Ru, Ir and Ru
as promoters. Table 12.4 shows a summary of chemical transformations performed
using glycerol as solvent.

12.5.2 Fats and Oils as Solvent for the Extraction of Natural

Products

Over the past two decades, scientists have successfully developed methods to extract
a variety of natural products using widely accessible vegetable oil. These approaches
were developed for the sole purpose of overcoming the utilization of VOC-based sol-
vents and to address the various challenges associated with promoting the employ-
ment of sustainable and eco-friendly resources in the extraction industry. In addition,
it is widely acknowledged in the literature that using vegetable oil for extraction can
help stabilize natural products and improve the different safety aspects of the obtained
natural products following formulation [89].
Chen et al. [90] successfully used soya oil to extract astaxanthin from crawfish
waste. The authors demonstrated that in order to achieve maximum pigment extrac-
tion, 1:1 ratio of oil to crawfish waste was needed. Equally, olive oil was used to
extract phenolic compounds from rosemary, dry oregano; this process significantly
increased the amount of phenolic contents by 1.7 and 3.5 times for rosemary and
oregano gourmet oils, respectively [91]. Extraction using vegetable oils was also
applied to isolate carotenoids from shrimp waste (Penaeus indicus); under optimum
conditions (2:1 ratio of oil to shrimp waste), sunflower oil was found to give the
highest yield when compared to other used oils [92].
On the other hand, Kang et al. were able to use soybean, corn, grapeseed and
olive oils to extract astaxanthin from micro-algae (Haematococcus pluvialis) [93].
Under the circumstances, up to 87.5% yield of the desired material was isolated
Table 12.3 Synthesis of useful chemical intermediates using glycerol as solvent
Reactants Product Conditions Ref
CHO N Aq. glycerol, 90 °C [65]
NH2
O
OH

CHO N Glycerol, 90 °C [66]

NH2
N
NH2

NH2 O H Glycerol, 90 °C [66]

N

NH2
N

NH2 H H Glycerol, 90 °C [67]

N

CHO
H
12 Vegetable Oils and Fats: Extraction, Composition and Applications

NH2 CHO O Glycerol, 90 °C [68]

H
O
H
N
H

(continued)
361
Table 12.3 (continued)
362

Reactants Product Conditions Ref

SH Na2 CO3 , glycerol, 120 °C, microwave [69]
S
S

Glycerol, 90 °C, microwave [70]

NH2 O N

NH2 O N

O N Glycerol, triacetylborate, 160–180 °C [71]

NH2
HO N
NH2 H

O NH2 O Glycerol, 65 °C [72]

O N

O O

SH S Glycerol, RT [73]

N SeCl
Glycerol, N2 , RT [74]
N Se
Z. Ghouila et al.

(continued)
Table 12.3 (continued)
Reactants Product Conditions Ref
NH2 Aq. glycerol, 90 °C [75]
HN
O O N
N
Cl
Cl

N3
Glycerol, 100 °C, microwave [76]

N N
N

OH O Glycerol, 90 °C [77]
CHO O
OH B
OH
OH N
N
H
12 Vegetable Oils and Fats: Extraction, Composition and Applications

NO 2 Glycerol, 90 °C [78]

N NO2
H

N
H
363
Table 12.4 Metal catalysed reactions using glycerol as solvent
364

Reagents Product Conditions Ref.

I NH 2 Glycerol, Cu(OAc)2 , KOH [79]

HN

Br Se Glycerol, Cu, Zn, 110 °C [80]

Se
Se

O Glycerol, KF, Al2 O3 , 90 °C [81]

CHO SH

O S

Glycerol, CuI, RT [82]

N3 N
N N

SH S Glycerol, Cu2 ONP, tBuOK, 100 °C [83]

I
O2N NO2
O2N

(continued)
Z. Ghouila et al.
Table 12.4 (continued)
Reagents Product Conditions Ref.
CHO OH Glycerol, Ru(p-cumene)Cl2 , NaOH + [84]
KOH, 60 °C

EtO2C CO2Et EtO2C CO2Et Glycerol, Grubbs I, surfactant, microwave, [85]

50 °C

O O Ir NHC, KOH, 120 °C [86]

OH
O
HO OH
HO OH

OH Glycerol, PdNP [87]

O
Br B
OH
O

OH Glycerol, NiCl2 ·glyme, DMSO, 80 °C [88]

B F4BN 2
12 Vegetable Oils and Fats: Extraction, Composition and Applications

OH

OH Aq. glycerol, 120 °C [89]

N O
H
NH2
365
366 Z. Ghouila et al.

when 1:1 mixture of oil and micro-algae were enriched at 25 °C. Refined edible
oil was equally used to isolate phenolic compounds from olive pomace and leaves
[94]. Similarly, phenolic compounds were also isolated using canola frying oil from
olive and hazelnut leaves; the extract was enriched with aqueous ethanolic extracts
at 200 ppm phenolic equivalence level [95].
Garcia-Martinez et al. were able to investigate the influence of olive variety and
the level of orchards on the content of phenolic compounds isolated from Sicilian
olive samples from eight different cultivars using Sicilian virgin olive oil (VOO) as
solvent [96]. The authors also studied the effect of VOO extracts on human MG-63
cell growth; during the study, it was found that such an effect was strongly dependent
on the type of cultivar and the grove altitude.
Corn oil was also used to extract a mixture of phenolic compounds and other
antioxidants from thyme dried flowers (Thymus capitatus) [97]. The unique antiox-
idant activity of the thyme oil makes it one of the highly considered and naturally
occurring antioxidant sources.

12.6 Fats and Oils as Synthons

The utilization of fatty acids as synthons and/or building blocks in chemical synthe-
sis was widely investigated by the synthetic organic chemistry community world-
wide. One of the earliest successful attempts was achieved by Elias J. Corey et al.
[98] who successfully synthesised 5-hydroxyeicosatetraenoic acid (5-HETE) start-
ing from readily available arachidonic acid (1). The latter compound underwent
an initial iodolactonization reaction in the presence of KI, I2 and KHCO3 in THF to
afford iodolactone 2. Further treatment of 2 with 1,5 diazabicyclo[5.4.0]undec-5-ene
(DBU) followed by lactone ring opening in the presence of MeOH and triethylamine
afforded the desired methyl ester of 5-HETE (3); this was then treated with lithium
hydroxide in a mixture of dimethoxyethane–water prompted the targeted 5-HETE
in quantitative yield (Fig. 12.3).
In a similar approach to Corey et al., Yamamoto et al. were able to synthesise a
series of oxidized fatty acids derivatives, namely 5-HEPA, 5-oxoEPA, 6-HOTE and 6-
oxoHOTE, starting from readily available fatty acid 4. Structure–activity relationship
(SAR) studies of the obtained oxidized fatty acids were performed for the activation
of peroxisome proliferator-activated receptors (PPARs) [99].
Langseter et al. also synthesised marine natural product 1,6Z,9Z,12Z,15Z-
octadecapentaen-3-one starting from either docosahexaenoic acid (DHA) in eight
steps or eicosapentaenoic acid (EPA) in 14 steps [100]. In a similar work by Jacob-
sen and co-workers, the authors demonstrated the synthesis of eicosatetraenoic acid
(ETA), docosapentaenoic acid (DPA) and stearidonic acid (SDA) from readily avail-
able EPA and DHA [101].
Methyl vernolate (8) was also used to generate a mixture of azidohydrin and
pyrrole. The former was successfully converted to furnish enantiomerically pure
aziridine 11 (Fig. 12.4) [101].
12 Vegetable Oils and Fats: Extraction, Composition and Applications 367

Fig. 12.3 Conversion of arachidonic acid to 5-HETE [98]

Fig. 12.4 Conversion of methyl vernolate (8) to pyrrole (10) and azide (9) and subsequent gener-
ation of aziridine (11)

Regio- and stereoselective Diels–Alder reaction was also performed on methyl

calandulate (12) with maleic anhydride. Under solvent-free conditions, the reaction
exclusively furnished the cis product 13 with high region and stereoselectivity [102]
(Fig. 12.5).
All-cis-4-chlorotetrahydropyran (14) was also synthesised from reaction of
methyl ester 15 with heptanal in the presence of AlCl3 as catalyst. Under these
conditions, the reaction proceeded with high without epimerisation to afford the
corresponding product with high enantiomeric excess [103] (Fig. 12.6).
A mixture of δ-stearolactone (16) (major) and γ-stearolactone (17) (minor) was
also obtained from treatment of fatty acid, oleic acid (18), with conc. H2 SO4 in DCM
(Fig. 12.7). The mixture contained 15:1 ratio of δ: γ stearolcatone [103].
368 Z. Ghouila et al.

Fig. 12.5 Conversion of

methyl calandulate (12) to
anhydride (13)

Fig. 12.6 Synthesis of

cis-4-chlorotetrahydropyran
(14) from methyl ester (15)

Fig. 12.7 Conversion of

oleic acid to stearolactone

Cross-metathesis reactions using derivatives of fatty acids were also exploited; a

variety of ruthenium base catalysts were used to affect this type of transformation.
For example, polyester monomers 19 and 20 were successfully synthesised from
addition of methyl ester 21 to methyl acrylate using Ru-based catalysts 22 or 23
[104] (Fig. 12.8).
The utilization of fatty acid derivatives as building blocks to gain access to vari-
ous polymers was also envisaged. Second-generation Grubbs catalyst was shown to
give highly ordered polymers when high-oleic sunflower oil and triglycerides were
subjected to metathesis conditions in the presence of chainstopper (Fig. 12.9). The
12 Vegetable Oils and Fats: Extraction, Composition and Applications 369

Fig. 12.8 Cross-metathesis reaction between methyl ester 21 and methyl acrylate

Fig. 12.9 ATMET approach for triglycerides in the presence of chainstopper

Fig. 12.10 Myristyl

myristate (24) and cetyl
ricinoleate (25)

term acyclic triene metathesis (ATMET) was coined to describe the process whereby
further cross-linking of the resulting polymer is prevented [105].
Other type of transformations of fatty acid derivatives involves the utilization of
enzymes as catalysts. In this regard, lipases are widely used industrially as catalysts
to produce cosmeceutical ingredients in the form of emollient esters such as myristyl
myristate (24) and cetyl ricinoleate (25) from mannitol or sorbitol in the presence of
fatty acids vinyl esters as donors of acyl groups (Fig. 12.10) [106, 107].
370 Z. Ghouila et al.

12.7 Future Trends: Sustainability

Prices of oilseeds are expected to increase over the medium term due to rising demand
for vegetable oil and protein meal but are not expected to attain any exponential highs.
The demand for protein meal is driven mainly by the growth in non-ruminant and milk
production and a greater incorporation rate of protein in feed rations in developing
countries. Vegetable oil consumption is driven mainly by food demand in developing
countries.
According to the OECD report [2], the issues and uncertainties will stay common
to most commodities (e.g. macroeconomic environment, crude oil prices and weather
conditions) in addition to each sector has its specific supply and demand sensitivities.
Questions over the sustainability of soybeans and palm oil production will be
critical as they stem from the high share of soybean production that comes from
genetically modified seeds and the expansion of oil palm plantations into rain forests.
However, certification schemes and labelling might bost demand for non-GMO mod-
ified sources, thus further area expansion is expected and subsequently resulting
in more supply growth.
Petroleum oil prices and biofuel policies in the USA, European Union and Indone-
sia will play a key role in bumping uncertainties in the vegetable oil sector because
of increasing share of vegetable oil production devoted to produce biofuels in these
countries. Since biodiesel is considered an advanced biofuel in the US Renewable
Fuel Standard mandates, all the uncertainties related to that policy have to be taken
into consideration. The proposal by the European Commission to reduce the amount
of first-generation biofuels that can be counted towards the renewable energy targets
from 10 to 5% remains an unachievable target.

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