_

Food Science and Technology Research, 22 (1), 83 89, 2016

Copyright © 2016, Japanese Society for Food Science and Technology
doi: 10.3136/fstr.22.83

http://www.jsfst.or.jp

Original paper

Effect of Different Treatment on the Properties of Coconut Milk Emulsions

Peipei Jiang, Dong Xiang* and Xibin Wang

Food Science Research Group, Food Science College, Hainan University, No. 58 People Road, Haikou, Hainan Province, China

Received March 8, 2015 ; Accepted September 9, 2015

Droplet size has an important effect on the stability and sensory quality of emulsions. This study aimed to
analyze the effect of different treatments, including treatment under different temperatures and shearing, on the
properties of coconut milk emulsions. Various coconut oil droplet sizes of coconut milk emulsion droplets after
different treatments were investigated by observing the droplet sizes and micrographs. The stability of these samples
was investigated by the creaming index of the emulsions. Result showed that heating increased the average droplet
size of coconut milk. Freezing decreased the average droplet size of the emulsion to a minimum of 7.67 µm. High-
speed shearing increased the average droplet size of the emulsion to a maximum of 10.29 µm. The creaming index of
the emulsion squeezed from coconut meat that underwent freezing treatment was 35.10%, which was the minimum
value. Thus, freezing treatment on coconut meat could induce the size of the emulsion droplets and improve the
stability of the emulsions.

Keywords: coconut milk, particle size, pretreatment, stability

Introduction phospholipids (Raghavendra and Raghavarao, 2010). Similar to all

An emulsion is a mixture of two immiscible liquids, in which emulsion, fresh coconut milk is not physically stable and is prone
one is the dispersed or internal phase comprising small spherical to phase separation. Within 5 _ 10 h of manufacture, coconut milk
droplets, and the other is the continuous, external phase. In food will separate into cream and serum layers, known as coconut cream
systems, the two liquid phases are usually oil and water. Food and coconut skim milk, respectively. However, the separated milk
emulsions can be categorized as oil-in-water or water-in-oil can be re-homogenized by shaking. Sometimes it will separate into
depending upon which phase is continuous (Ariyaprakai and three or four phases, which are grey precipitate layer, serum layers,
Tananuwong, 2015; Qiao et al., 2015; Schmidt et al., 2015). cream layer and oil layer, respectively (Chambal et al., 2012; Ng et
Coconut milk is a natural oil-in-water emulsion extracted from the al., 2014).
endosperm of mature coconut, and it contains about 54% moisture, Many of the properties of an emulsion, i.e., stability,
35% fat, and 11% solid non-fat (Ng et al., 2014; Saikhwan et al., appearance, and texture, depend on the droplet size. The major
2015; Zhu et al., 2014). Coconut milk has been used as an reason for the instability of coconut milk emulsion is its poor
important ingredient for Asian cuisine, as well as in other parts of emulsifying properties, low surface activity of coconut protein, and
the world because of its unique flavor and other desirable sensory large droplet size (Chambal et al., 2012).
characteristics (Iguttia et al., 2011). In China, coconut milk is an Proteins are absorbed at the surface of the droplets and provide
important ingredient for beverages. According to statistics, about repulsive interactions (e.g., electrostatic and steric) that help prevent
25% of the outputs of coconuts are consumed as coconut milk droplet aggregation (Tangsuphoom and Coupland, 2009a). The
(Marina et al., 2009; Tipvarakarnkoon et al., 2010). emulsifying properties of proteins are influenced by their structures,
Coconut milk is stabilized by the coconut proteins and which are affected by environmental factors (e.g., pH, temperature)

*To whom correspondence should be addressed. E-mail: foods2003@126.com.

84 P. Jiang et al.

(Ariyaprakai et al., 2013; Ariyaprakai and Tananuwong, 2015; Neta Table 1 . Coconut meat with different thermal treatments
et al., 2012; Tangsuphoom and Coupland, 2009b). In China, coconut
Code Thermal treatment
milk squeezed from coconut meat as raw material is usually used as
a beverage. In factories, coconut meat is processed within 8 h A Normal temperature at 30℃
B Chilling at 4℃
without cooling. Therefore studies on the effect of low temperature
C Freezing at _18℃
on the properties of coconut milk are needed. Coconut meat is
D Heating at 80℃
usually treated at 80℃ prior to squeezing, which can inactivate the
E Heating at 80℃ followed by chilling at 4℃
coconut protein enzyme in the material. During coconut milk F Heating at 80℃ followed by freezing at _18℃
production, coconut milk needs to be subjected to high-speed shear
homogeneous pretreatment. Generally, this type of pretreatment may
Fat content = (m1 _ m2) / (m*v1/v)*100% ······Eq. 1
enhance the stability of the product. In this study, the authors
investigated the effects of different pretreatment temperatures on Where m1 is the mass of the empty flask (g), m2 is the mass of the
coconut meat by measuring the fat content, droplet size, and flask and fat, m is the mass of sample, v is the volume of the
creaming index. Moreover, microstructures were observed using measured ether layer, and v1 is the volume of the liquid transferred
optical microscopy. The authors also investigated the influence of to the flask.
high-speed shearing process on the droplet size and stability of Determination of the particle size of coconut milk emulsion
coconut milk. droplets The mean size of coconut milk emulsion droplets was
measured using a laser particle analyzer (WJL-602, Shanghai
Materials and Methods instrument physical optics instrument Co., LTD., Shanghai, China).
Materials Whole mature coconuts (aged 8 _ 10 months) were Set the continuous phase as water, its relative index is 1.33, and the
purchased from a local retailer. dispersed phase as coconut oil. Then samples of coconut milk
Sample preparation Mature coconuts were shelled and peeled (~0.5 mL) were placed into the sample cell with 400 mL distilled
using a traditional coconut cutter, and the fresh white coconut meat water in it. The droplet size was given by D10, D90 and Dav, which
was left in the shells. Under normal temperature treatment at 30℃, are the representative diameters of 10%, 90% and the mean
coconut meat was used to squeeze coconut milk directly without diameter of coconut milk emulsion droplets, respectively. The
any other pretreatment. In heating process, coconut meat was droplet size distribution determination was based on the Mie
treated in a water bath (HH4 digital constant temperature water scattering theory.
bath pot, Changzhou Aohua instrument Co., Ltd., Changzhou, Microscopy Samples of coconut milk (~1 μL) were placed on
China) at 80℃ for 15 min. During low temperature treatment (4℃ a microscope slide, gently covered with a cover slip, and observed
and _18℃), coconut meat was placed in the refrigerator for 24 h. at 100× magnification using an optical microscope (OPTEC®
The different pretreatments are presented in Table 1. BDM500, Chongqing Optec instrument Co.,Ltd., Chongqing,
Coconut milk was produced by squeezing the shredded coconut China) equipped with a color video camera.
meat and filtering it through a piece of double-layered cheesecloth. The optical micrographs were analyzed using image analysis
Under machine treatment, coconut milk was sheared by a high- software (OPTPro2012, Chongqing Optec instrument Co.,Ltd.,
speed shearing machine (FJ-200, Shanghai Specimen model Chongqing, China). Pictures were obtained from different fields on
factory, Shanghai, China) at a rotation of 11,000 r/min for 1 min. each slide, and representative images are presented.
Determination of fat content of coconut milk Aliquots of Evaluation of physical stability About 10 mL of coconut milk,
coconut milk (10 mL) were transferred into a liposuction bottle. including non-sheared and sheared emulsion, was transferred to
Approximately 1.25 mL of aqueous ammonia was added into the flat-bottomed test tubes. These tubes were then covered and
bottle, which was fully mixed. The bottle was treated in a water incubated at 30℃ for 12 h. All samples resulted in the formation of
bath at 60℃ for 5 min, shaken manually for 2 min, added with two phases, namely, the opaque layer at the top and transparent
10 mL of ethanol, and mixed thoroughly. Subsequently, 25 mL of aqueous phase at the bottom during storage. Upon measuring the
diethyl ether were added into the bottle, shaken for 0.5 min, 25 mL height of the bottom layer, the creaming index was calculated using
of light petroleum were then added followed by shaking for equation Eq. (2):
0.5 min, and let stand for 30 min. The volume of the top layer was
Creaming index = h / H *100% ······Eq. 2
measured. Some liquid in the ether layer was transferred to an
empty flask by sucking the liquid gently. The flask was distilled to Where h means the height of the bottom layer, and H means the
recycle ether and petroleum ether. After being placed in a loft drier total height of coconut milk in the tube. The smaller the creaming
for 1.5 h, the sample was weighed. This process was repeated until index, the more stable the coconut milk.
the flask reached a constant weight. The fat content was calculated Statistical analysis All the experiments were conducted in
using Eq. (1). triplicate, and freshly prepared coconut milk was used in all
Effect of Different Treatment on the Properties of Coconut Milk Emulsions 85

experiments. Data of fat content, average droplets size and Table 2 . Fat content of coconut milk squeezed from coconut
creaming index were analyzed using statistical software (Minitab meat with different treatments prior to extraction
15, Minitab Inc, America). The standard deviation (SD) and Code Fat content (%)
Tukey’s multiple range tests were used to evaluate significant
A 27 . 52 ± 1 . 42a
differences (p < 0.05) between the samples. Data are presented as B 19 . 61 ± 1 . 21b
the mean values ± SD. C 15 . 94 ± 0 . 50c
D 20 . 94 ± 1 . 94b
Results and Discussion E 20 . 37 ± 0 . 84b
Effect of different thermal treatment on the fat content of F 28 . 17 ± 0 . 62a
coconut milk The fat content of coconut milk from coconut meat Mean values ± standard deviation. Values with different
exposed to different pretreatments is described in Table 2. The fat superscript are significantly different (p < 0.05) (Tukey test).
content of coconut milk after freezing process at _18℃ was the
A represents normal temperature at 30℃, B represents chilling
at 4℃, C represents freezing at _18℃, D represents heating
lowest (15.94% fat), possibly because of the crystallization of at 80℃, E represents heating at 80℃ followed by chilling at
coconut oil (Ariyaprakai and Tananuwong, 2015), which indicated 4℃, and F represents heating at 80℃ followed by freezing at
_18℃.
that coconut oil could easily crystallize below 25℃, and frozen
coconut meat was difficult to thaw in a short time period, so parts
of coconut oil were not extracted from coconut meat, and decreased thermal treatment. Upon comparing the left and right images, the
the content of coconut oil in coconut milk. The fat content of average droplet sizes with heating process were bigger compared
coconut milk after heating at 80℃ followed by freezing at _18°C with those without heating process. The difference in average
was the highest (28.17% fat), which was slightly higher than the fat droplet size among the normal temperature at 30℃, chilling at 4℃,
content of normal temperature at 30℃. Maybe because that cells, and heating at 80°C followed by chilling at 4℃ was small.
cellulose, and other structures of the coconut were damaged under Freezing process resulted in the smallest average droplet size, but
the two kinds of extreme temperature conditions which made more heating process followed by freezing process remarkably increased
oil extracted and more coconut protein denatured. Moreover, the the particle sizes.
oil combined to the denatured protein, thereby leading to more fat Effect of different pretreatments on the coconut oil droplets
being squeezed out. Chilling, heating, and heating followed by size of sheared process.
chilling for coconut meat had no significant effects on the Table 4 shows the results of coconut oil droplets size of
extraction of coconut milk fat, and the fat contents after these three coconut milk with high-speed shearing for 1 min followed by
treatments were all lower than that after normal temperature at undergoing different thermal process. The coconut oil average
30℃, but comparing with others, there are significant differences. droplets sizes (Dav) of sheared coconut milk after normal
And freezing for coconut meat had significant effects on the temperature at 30℃, chilling at 4℃ and freezing at _18℃ were
extraction of coconut milk fat. 9.43, 8.84 and 8.48 µm, the Dav of sheared coconut milk after
Effect of thermal pre-treatments on the droplet size of coconut undergoing heating, heating followed by chilling, and heating
milk Effect of different pre-treatments on the coconut oil droplet followed by freezing were nearly 9.71, 9.18 and 10.29 µm, which
size of non-sheared process. demonstrate that heating could increase the droplet size. Among all
As shown in Table 3, the coconut oil droplet sizes of coconut the treatment groups, heating increased the D10, D90, and Dav, But
milk changed with different thermal process of fresh coconut meat. there was no significant difference of D­1 0 between normal
In terms of mass, the average droplet sizes of coconut milk after temperature at 30℃ and heating at 80℃. Freezing decreased the
heating process at 80℃ were larger than that of coconut milk coconut oil droplet size, D10, D90 and Dav to 3.74, 14.54, 8.48 µm.
without heating pretreatment. After heating process, the droplet heating followed by freezing increased D10, D90, and Dav to a
size at 10% cumulative volume (D10), the droplet size at 90% maximum value of 4.46, 17.43 and 10.29 µm.
cumulative volume (D 90 ) and the mean droplet size (Dav) Fig. 2 shows the droplet size and distribution of coconut oil of
increased. The Dav increased to 10.03 and 9.60 µm after heating at sheared coconut milk after different thermal treatment. The coconut
80℃ for 15 min and heating at 80℃ followed by freezing at _18℃, oil droplets size after chilling at 4℃, normal temperature at 30℃,
respectively. Chilling at 4℃ and freezing at _18℃ decrease the heating at 80℃, and heating at 80℃ followed by chilling at 4℃
D , D and Dav. Freezing at _18℃ resulted in the smallest droplet
10 90 were larger compared with the droplets size after freezing. These
size Dav and D90, 7.67 and 13.52 µm. Chilling process results in the findings were consistent with the results in Table 4.
smallest D10, 3.15 µm. The Dav was approximately between 8.12 Based on the measured results and microscope observation, the
and 9.33 µm after normal temperature at 30℃, chilling at 4℃, and coconut oil droplets size of coconut milk with heating pre-
heating at 80℃ followed by chilling at 4℃. treatment were larger than those of coconut milk without heating
Fig. 1 shows the microstructure of coconut milk after different pre-treatment. The reason may be that coconut milk is a natural
86 P. Jiang et al.

Table 3 . Coconut oil droplet sizes of non-sheared coconut milk from coconut milk
exposed to different thermal treatments prior to coconut milk extraction

Coconut oil droplet size (µm)

Code
D10 D90 Dav
A 3 . 87 ± 0 . 00a 16 . 33 ± 0 . 21b 9 . 33 ± 0 . 10c
B 3 . 15 ± 0 . 04c 14 . 58 ± 0 . 47c 8 . 12 ± 0 . 22d
C 3 . 30 ± 0 . 05c 13 . 52 ± 0 . 08d 7 . 67 ± 0 . 03e
D 3 . 97 ± 0 . 06a 17 . 72 ± 0 . 05a 10 . 03 ± 0 . 01a
E 3 . 81 ± 0 . 01b 15 . 54 ± 0 . 02c 8 . 87 ± 0 . 00c
F 4 . 01 ± 0 . 01a 16 . 64 ± 0 . 05b 9 . 60 ± 0 . 03b
Mean values ± standard deviation. a-e.Values with different superscript letters in the
same column are significantly different (p < 0.05) (Tukey test). A represents normal
temperature at 30℃, B represents chilling at 4℃, C represents freezing at _18℃, D
represents heating at 80°C, E represents heating at 80°C followed by chilling at 4℃,
and F represents heating at 80°C followed by freezing at _18℃.

Fig. 1. Micrographs of oil in non-sheared coconut milk. A represents normal temperature at 30℃, B represents
chilling at 4℃, C represents freezing at _18℃, D represents heating at 80℃, E represents heating at 80℃
followed by chilling at 4℃, and F represents heating at 80℃ followed by freezing at _18℃.
Effect of Different Treatment on the Properties of Coconut Milk Emulsions 87

Table 4 . Coconut oil droplet sizes of sheared coconut milk from coconut meat treated
with different thermal treatment prior to coconut milk extraction

Coconut oil droplet size (µm)

Code
D10 D90 Dav
A 4 . 17 ± 0 . 04b 16 . 10 ± 0 . 39b 9 . 43 ± 0 . 24c
B 3 . 64 ± 0 . 04d 15 . 56 ± 0 . 03b 8 . 84 ± 0 . 01e
C 3 . 74 ± 0 . 02d 14 . 54 ± 0 . 01c 8 . 48 ± 0 . 00e
D 4 . 12 ± 0 . 02b 16 . 85 ± 0 . 07a 9 . 71 ± 0 . 03b
E 3 . 98 ± 0 . 00c 15 . 91 ± 0 . 46b 9 . 18 ± 0 . 22d
F 4 . 46 ± 0 . 01a 17 . 43 ± 0 . 11a 10 . 29 ± 0 . 03a
Mean values ± standard deviation. a-e. Values with different superscript letters in the
same column are significantly different (p < 0.05) (Tukey test). A represents normal
temperature at 30℃, B represents chilling at 4℃, C represents freezing at _18℃, D
represents heating at 80℃, E represents heating at 80℃ followed by chilling at 4℃, and
F represents heating at 80°C followed by freezing at _18℃.

Fig. 2. Micrographs of oil in sheared coconut milk. A1 represents normal temperature at 30℃, B1 represents
chilling at 4℃ C1 represents freezing at _18℃, D1 represents heating at 80℃, E1 represents heating at 80℃
followed by chilling at 4℃, and F1 represents heating at 80℃ followed by freezing at _18℃.
88 P. Jiang et al.

emulsion, with stability that is supported by its own coconut with the measurement results, which could be observed during the
proteins (globulin and albumin) and phospholipid. The quality and shearing process of this experiment. Second, in high-speed shearing
content of coconut protein determine the stability of coconut milk, process, the strong shear force will result in the droplets of coconut
and coconut protein is highly sensitive to temperature, and it will milk to randomly move at a high speed, in addition to the poor
result in coagulation when heated to 80℃ (Saikhwan et al., 2015; quality and quantity of coconut protein, oil droplet, as a kind of
Zhu et al., 2014). Thus, proteins on the coconut meat surface were liquid, maybe easily cause extrusion and collision with each other,
destroyed by heating, which resulted in the protein content in subsequent cause flocculation, and even coalescence, thereby
coconut milk and the protein adhering to the oil drop surface increasing the particle size of oil droplets. The phenomenon of
decreased, subsequent caused the oil droplets inter-attraction, flocculation and coalescence was observed under the microscope.
flocculation, and even coalescence, hence, increased coconut oil Effect of different treatments on the stability of coconut milk
droplet size of coconut milk, and instability. The main reasons for Effect of different thermal pretreatments on the stability of coconut
the biggest difference in the droplet size between freezing process milk
and heating process followed by freezing process are discussed as Creaming index is an important indicator to evaluate the
follows. Coconut fiber may have been destroyed by freezing and stability of coconut milk emulsions. The smaller the creaming
coconut oil crystallized, so more coconut proteins and little coconut index, the more stable the coconut milk emulsion. As shown in
oil (Table 2) were extracted through squeezing coconut milk. More Fig.3, the creaming index of coconut milk squeezed from coconut
proteins adhered to the oil drop surface, which inhibited the inter- meat with chilling was not significantly different from that of
attraction of coconut oil, thereby decreasing the particle size. coconut milk from meat with normal temperature at 30℃. By
However, heating followed by freezing markedly increased the contrast, freezing process decreased the creaming index of both
particle size. The fiber and cells of coconut meat were damaged sheared and non-sheared coconut milk to below 40%. The
and became loose, and heating thawed coconut oil, most of the creaming index of samples with heating and heating followed by
coconut proteins were denatured when heated, but more oil were chilling increased, and both treatments exhibited a creaming index
extracted (Table 2), only a small amount of proteins adhered to the approaching 70%. The creaming index of samples with heating
oil drop surface, which resulted in the inter-attraction of coconut followed by freezing was the largest.
oil, flocculation, and coalescence; hence, the average droplet size In terms of mass, the creaming index of samples with heating
increased. However, the mechanism underlying this phenomenon pretreatment significantly increased, especially between freezing
needs to be further researched in the future. and heating followed by freezing. The creaming index of samples
The difference of coconut oil droplet size between non-sheared with freezing pretreatment was the smallest, and the stability was
and sheared coconut milk By comparing Tables 3 and 4 and the best. These data also illustrated that smaller coconut oil droplet
Figs.1 and 2, we can conclude that high-speed shearing process sizes of coconut milk emulsion resulted in highly stable coconut
could increase the coconut oil droplet size. Among all the treatment milk. Coconut milk is a natural emulsion stabled by coconut
groups, the coconut oil droplets size D10, D90 and Dav of sheared protein, which is sensitive to temperature, thus heating denatured
coconut milk after heating followed by freezing were the biggest at the coconut protein, which is the main factor to make coconut milk
nearly 4.46, 17.43 and 10.29 µm, which is larger than that of non- unstable. Freezing process made coconut oil crystallize, fiber and
sheared coconut milk. The Dav of sheared coconut milk after cell break, so less oil and more coconut protein extracted from
freezing, heating followed by chilling, and heating followed by coconut meat, than more protein adhered to the coconut oil droplet
freezing were 8.48, 9.18, 10.29 µm respectively, which is larger surface, which inhibited the attraction of coconut oil, thus freezing
than that of non-sheared coconut milk significantly. However, the improve the stability of coconut milk. However, heating followed
coconut oil droplets size D90 of sheared coconut milk after normal by freezing markedly decreased the stability of coconut milk,
temperature at 30℃ and heating process were smaller than that of maybe because that the fiber and cells of coconut meat were
non-sheared coconut milk. The Dav of sheared coconut milk after damaged and became loose, and heating thawed coconut oil, most
heating was 9.71 µm, which is also smaller than that of non-sheared of the coconut proteins were denatured when heated, but more oil
coconut milk. were extracted, only a small amount of proteins adhered to the oil
Theoretically, high-speed shearing to emulsion will cause droplet surface, which resulted in the attraction of coconut oil,
centrifugal shearing force, extrusion and collision of coconut milk flocculation, and coalescence, hence, the stability was the worst.
to broke and scatter oil droplets; thus, oil droplets become smaller Effect of high-speed shearing on the stability of coconut milk
(Wu, 2014). However, the data in Tables 3 and 4 show that, high- Fig. 3 shows the results of the creaming index with machine
speed shearing resulted in larger average droplet sizes. The possible treatment. Compared with non-sheared coconut milk, the creaming
reasons for this finding are followed. First, coconut milk has index of coconut milk squeezed from coconut meat with chilling,
foaming properties, so high-speed shearing process can produce a heating, and heating followed by freezing decreased and their
large number of bubbles with large droplet sizes that may interfere stability improved, but that with normal temperature at 30℃ and
Effect of Different Treatment on the Properties of Coconut Milk Emulsions 89

Ariyaprakai, S., Limpachoti, T., and Pradipasena, P. (2013). Interfacial and

emulsifying properties of sucrose ester in coconut milk emulsions in
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Chambal, B., Bergenståhl, B., and Dejmek, P. (2012). Edible proteins from
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by electrophoresis and mass spectrometry. Food Res. Int., 47, 146-151.
Iguttia, A. M., Pereira, A. C. I., Fabiano, L., Silva, R. A. F., and Ribeiro, E.
P. (2011). Substitution of ingredients by green coconut (Cocos nucifera
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Marina, A. M., Che Man, Y. B., and Amin, I. (2009). Virgin coconut oil:
emerging functional food oil. Trends Food Sci. Tech., 20, 481-487.
Neta, N. D. A. S., Santos, J. C. S. D., Sancho, S. D. O., Rodrigues, S.,
Fig. 3. Effect of different treatment on the creaming index of
coconut milk. A represents normal temperature at 30℃, B represents Gonçalves, L. R. B., Rodrigues, L. R., and Teixeira, J. A. (2012).
chilling at 4℃, C represents freezing at _18℃, D represents heating Enzymatic synthesis of sugar esters and their potential as surface-active
at 80℃, E represent heating at 80℃ followed by chilling at 4℃, and
stabilizers of coconut milk emulsions. Food Hydrocolloids, 27, 324-331.
F represents heating at 80℃ followed by freezing at _18℃. Open
bars represent the creaming index of non-sheared coconut milk, and Ng, C. Y., Mohammad, A. W., Ng, L. Y., and Jahim, J. M. (2014).
filled bars represent the creaming index of sheared coconut milk. Membrane fouling mechanisms during ultrafiltration of skimmed coconut
milk. J. Food Eng., 142, 190-200.
freezing increased insignificantly, that with heating followed by Ng, S. P., Lai, O. M., Abas, F., Lim, H. K., and Tan, C. P. (2014). Stability
chilling has no significantly change. These data illustrated that the of a concentrated oil-in-water emulsion model prepared using palm
major reason resulted in the larger droplet size after shearing process, olein-based diacylglycerol/virgin coconut oil blends: Effects of the
may be lots of bubbles produced during the shearing process. rheological properties, droplet size distribution and microstructure. Food
Res. Int., 64, 919-930.
Conclusions Qiao, X., Wang, L., Shao, Z., Sun, K., and Miller, R. (2015). Stability and
Similar to oil-in-water emulsions, coconut milk emulsions are rheological behaviors of different oil/water emulsions stabilized by
unstable. The oil droplets in coconut milk are attracted to each natural silk fibroin. Colloids and Surfaces A, 475, 84-93.
other, which results in flocculation or coalescence. The droplets Raghavendra, S. N. and Raghavarao, K. S. M. S. (2010). Effect of different
size of coconut milk emulsion is an important indicator to assessing treatments for the destabilization of coconut milk emulsion. J. Food
the stability of coconut milk. Different pretreatments of coconut Eng., 97, 341-347.
meat clearly changed the sizes of droplets. In this study, heating Saikhwan, P., Thongchan, S., Jumwan, N., Thungsiabyuan, P.,
treatment of coconut meat could increase the size of droplets, Sakdanuphap, J., Boonsom, S., Kraitong, P., and Danwanichakul, P.
freezing decreased the content and the droplet size of coconut oil, (2015). Cleaning studies of coconut milk foulants formed during heat
high-speed shearing caused larger droplet sizes. In china, in the treatment process. Food Bioprod. Process., 93, 166-175.
process of producing coconut milk, coconut meat will be heating at Schmidt, U. S., Bernewitz, R., Guthausen, G., and Schuchmann, H. P. (2015).
80℃ before squeezed, and the fresh coconut milk will be sheared Investigation and application of measurement techniques for the
before adding surfactants, which were considered to inactivate the determination of the encapsulation efficiency of O/W/O multiple emulsions
enzymes on the surface of coconut meat and improve the stability stabilized by hydrocolloid gelation. Colloids Surfaces A, 475, 55-61.
of coconut milk. But the result of this experiment shows that Tangsuphoom, N. and Coupland, J. N. (2009a). Effect of surface-active
heating and high-speed shearing is not the ideal method to improve stabilizers on the surface properties of coconut milk emulsions. Food
the stability of coconut milk. This study provided a theoretical Hydrocolloids, 23, 1801-1809.
basis for the factory producing. Tangsuphoom, N. and Coupland, J. N. (2009b). Effect of thermal treatments
on the properties of coconut milk emulsions prepared with surface-active
Acknowledgements The authors thank Bin Li, Weimin Zhang, and stabilizers. Food Hydrocolloids, 23, 1792-1800.
Mengqi Lu for their assistance in this experiment and thesis. The Tipvarakarnkoon, T., Einhorn-Stoll, U., and Senge, B. (2010). Effect of
authors also thank Chuanwen Hong for his great contribution to the modified Acacia gum (SUPER GUM™) on the stabilization of coconut
experiment and thesis. o/w emulsions. Food Hydrocolloids, 24, 595-601.
Wu, S. (2014). Degradation analysis of pectin treated by microwave and
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