INTRODUCTION
Fortified dairy products appeal to a wide variety
of consumers and help them increase their intake of
bioactive components. Kashk is a local name for a
traditional low-fat dried yogurt in Iran. It is obtained
from boiled and concentrated yogurt and is available in
a semi-liquid or dried form. Liquid kashk contains 20–
25% nonfat solids, 1% fat, 3% salt, and at least 13%
protein [1].
Coffee is one of the most consumed and commercialized
food products in the world and one of the
most traded commodities, second only to petroleum [1].
It has various biological and pharmacological properties,
such as antioxidant, anti-inflammatory, and antimicrobial
properties, as well as other health benefits [2].
Natural therapy is a modern approach to preventing
common diseases. Therefore, coffee bean extract or
powder can be used in cosmetic products and numerous
functional foods [1, 3–5]. However, natural antioxidants
are usually heat sensitive and susceptible to oxidation,
which limits their application in food industry [6].
Microencapsulation is a promising technique that
protects bioactive materials and controls the release
of entrapped ingredients [1]. Over the last few years,
encapsulation has attracted much attention in food,
pharmaceutical, and cosmetic industries due to its wide
application in the design of functional products [1].
Encapsulation techniques are often based on drying
processes, such as spray-drying or freeze-drying, due
to the liquid nature of extracts containing bioactive
compounds [7]. Several studies have investigated the
protective role of these techniques against adverse
conditions to which extracts can be exposed. They found
that encapsulation promoted better volatile retention
Research Article DOI: http://doi.org/10.21603/2308-4057-2020-1-40-51
Open Access Available online at http://jfrm.ru/en/
Effects of encapsulated green coffee extract
and canola oil on liquid kashk quality
Elnaz Rahpeyma1 , Seyed Saeed Sekhavatizadeh2,*
1 Department of Food Science, Sarvestan branch, Islamic Azad University, Sarvestan, Iran
2 Fars Agricultural and Natural Resources Research and Education Center, AREEO, Shiraz, Iran
* e-mail: s.sekhavati@areeo.ac.ir
Received November 01, 2019; Accepted in revised form January 09, 2019; Published February 25, 2020
Abstract: In this study, we used a water-in-oil (W/O) emulsion encapsulation technique to enhance green coffee extract
in the novel kashk product and protect it against hot filling. Green coffee extracts (GCE) in free (1%, 0.5%, and 0.25%) and
encapsulated form (EGCE) (5%, 2.5%, and 1.25%) were added to kashk during hot filling, and their physicochemical and sensory
properties were investigated. The EGCE kashk had higher oxidative stability (0.43 h) than the control due to the extract’s high
phenolic content and DPPH radical scavenging activity (74%). Although a high concentration of GCE caused a higher pH (4.02),
the latter declined in all the samples during the storage period. Further, the size of droplets in the emulsion varied from 3.20 to
8.51 μm, confirming the well-encapsulated GCE by Fourier transform infrared. In addition, palmitic acid and oleic acid were
detected in GCE by gas chromatography as the main saturated and unsaturated fatty acids, respectively. All the treatments had
similar rheological properties and the highest flow index was observed in the samples with EGCE 5% on day 60. The sensory
evaluation showed that the assessors preferred the kashk formulated with 1% GCE. Finally, GCE encapsulation protected
the color of the samples, and the b* value remained unchanged, whereas the lightness (L*) increased. We suggest that a W/O
emulsion is a successful technique for GCE encapsulation in kashk and can offer the latter to consumers as an alternative type of
flavored dairy product with a better shelf life and health benefits.
Keywords: Antioxidant activity, encapsulation, green coffee extract, kashk, rheological properties
Please cite this article in press as: Rahpeyma E, Sekhavatizadeh SS. Effects of encapsulated green coffee extract and canola oil
on liquid kashk quality. Foods and Raw Materials. 2020;8(1):40–51. DOI: http://doi.org/10.21603/2308-4057-2020-1-40-51.
Copyright © 2020, Rahpeyma et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International
License (http://creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix,
transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.
Foods and Raw Materials, 2020, vol. 8, no. 1
E-ISSN 2310-9599
ISSN 2308-4057
41
Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
and increased the shelf life of bioactive components
and extracts [8–11]. There are numerous studies about
encapsulation of coffee extract and its antioxidant
compounds [12–14].
The incorporation of green coffee extract (GCE)
in kashk has not been reported so far. Since kashk is
prepared using hot filling, and heating causes a loss of
antioxidants, GCE was encapsulated using a waterin-
oil (W/O) emulsion technique. Thus, our aim
was to investigate the physicochemical and sensory
characteristics of kashk incorporated with free and
microencapsulated GCE during the storage period.
STUDY OBJECTS AND METHODS
Materials. Green coffee (Robusta coffee) was
supplied from the local market of Shiraz (Fars, Iran).
Starter culture (-CH1-DVS-50U) was purchased from
Christian Hansen (Denmark), and all chemical reagents
were obtained from Merck Co. (Germany).
The research was conducted at the Fars Agricultural
and Natural Resources Research and Education Center.
Green coffee extraction. According to the slightly
modified method of Upadhyay and Ramalakshmi, 10 g
of ground coffee was added to 100 mL of distilled water
and held in a hot water bath for 30 min [2]. Then the
slurry was cooled at room temperature and filtered to
obtain a clear extract for analysis.
Microencapsulation. GCE was microencapsulated
using a W/O emulsion technique based on the Tran
et al. method with slight modifications [15]. Glycerol
monostearate (GMS) with HLB 3.8 (1.5 wt%) was added
to canola oil and shaken at 4000 rpm at 70°C. Then,
the aqueous solution containing the GCE was heated
to 40°C. The W/O emulsion (10:90) was prepared by
blending the GCE-containing aqueous phase and the
GMS-containing canola oil phase at 27000 rpm and
70°C for 2 min. Then, the suspension was cooled while
stirring with a magnetic at 1000 rpm for 2 h and left
for 30 min for microcapsules to precipitate. Finally,
the suspension was centrifuged at 350 g and 4°C for
10 min. The precipitate was washed twice with saline
and filtered. The obtained microcapsules were stored in
a refrigerator until usage.
GCE kashk production. Liquid kashk was prepared
according to the method described in [1]. Then, free
and encapsulated green coffee extracts in different
amounts (0.25‒5%) were added to kashk. The samples
were named GCE 1%, GCE 0.5%, GCE 0.25%, EGCE
5%, EGCE 2.5%, and EGCE 1.25%. The sample without
GCE was used as a control.
Total phenolic content. The amount of total
phenol in different concentrations of the extracts
was determined according to Folin-Ciocalteu
as described by Ballesteros et al., with some
modifications [12]. Briefly, the samples (0.1 mL)
were introduced into test tubes containing 0.75 mL
of Folin–Ciocalteu’s reagent and 0.75 mL
of 2% sodium carbonate. The tube was mixed and
kept for 1 h in the darkness at room temperature. The
absorbance was measured at 765 nm using a UNICO
2100 UV–vis spectrophotometer. Phenolic compounds
were measured in triplicate, and the results were
averaged. A calibration curve of gallic acid (ranging
from 25 to 100 mg mL–1) was prepared in methanol.
The results, which were determined by the regression
equation of the calibration curve (y = 0.000245x –
0.0377; correlation coefficient r = 0.998), were expressed
as gallic acid (GA) mg equivalents g–1 sample.
Antioxidant activity. The free radical scavenging
activity of GCE was measured by using the
1,1-diphemyl-2-picryl-hydrazyl (DPPH) following the
method of Ribeiro et al. with a slight modification [16].
A DPPH solution was added to the extract and mixed.
Then, the mixture was kept at room temperature in the
darkness for 1 h. The absorbance of resulting solutions
was measured at 515 nm. The blank sample was
prepared in the same manner except that methanol was
used instead of the DPPH solution. A standard curve was
prepared using TBHQ (tertiary butylhydroquinone) at
different concentrations. The percentage of scavenging
activity was calculated as below:
% of scavenging = [(A0–A1) (A0)–1] × 100 (1)
where A0 is the absorbance of the control and A1 is the
absorbance of the sample turbidity factor. Finally, IC50
(an absorbance value of 0.5 in the reducing power assay)
was calculated.
Oxidative stability. The 892 Professional Rancimat
(Metrohm, Herisau, Switzerland) was used to determine
the oxidation stability of the samples. Three grams of the
sample was heated at 110°C under a purified air flow rate
of 20 L h–1.
pH value. The pH of kashk enriched with GCE
was measured using a pH meter (Greisinger electronic,
Germany).
Particle size distribution. The mean particle size
of the microcapsules was measured using a dynamic
light scattering technique at ambient temperature (Nano
Particle Analyzer SZ-100, Horiba, Germany).
Fourier transform infrared spectroscopy (FTIR).
The FTIR analysis of GCE and EGCE was recorded by
a Perkin-Elmer Spectrum RXI spectrometer (USA) in
the transmit mode in the range of 400–4000 cm–1 in KBr
pellets at a resolution of 4 cm–1. A DLaTGS (Deuterated
Triglycine Sulphate Doped with L-Alanine) detector was
used to perform the measurements at room temperature
(25 ± 0.5°C) at 24 scan/min to find possible functional
groups.
Fatty acid composition. The fatty acid composition
was determined according to the Golmakani et al.
method [17].
Rheological measurements. Viscosity was
measured using a Brookfield rotational viscometer
(Model LVDV I+, Version 3.0, Stoughton, MN, USA)
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Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
with a spindle C30 and a heating circulator. The kashk
samples were mixed for 5 min at room temperature at
60 rpm. Flow behavior was described using the Power
law, Bingham, and Casson models according to
equations:
τ = kγn (Power law model) (2)
σ–σ0 = ηγ (Bingham model) (3)
σ0.5 = k0c + kc(γ)0.5 (Casson model) (4)
where τ is the shear stress, Pa; γ is the shear rate, s–1; k is
the consistency coefficients, Pa·sn; η is Bingham plastic
viscosity; kc is Casson plastic viscosity; n is the flow
index, and σ0 and k0c are yield stress of Bingham and
Casson models, respectively.
Color analysis. Changes in kashk color were
measured using a Choroma CR-400 meter (Japan). L, a
and b values were expressed as L* (black to white), a*
(green to red), and b* (blue to yellow) [18].
Sensory analysis. Sensory properties of the samples
were determined by 30 panelists. Sensory analysis included
aroma, color, taste, and overall acceptability. It used a
five-point hedonic scale, with 5 indicating “like extremely”
and 0 “dislike extremely”, compared to the control sample.
The analysis lasted 7 consecutive days [19].
Statistical analysis. A one-way analysis of variance
(ANOVA) was performed at a confidence level of 0.05
(SPSS version 16.0). The means were compared using
the Duncan’s multiple range at a significance level of
0.05. All experiments were performed in triplicate.
RESULTS AND DISCUSSION
Total phenolic content. The total phenolic content of
GCE is presented in Table 1.
Тhe content of phenols in a 1200 ppm concentration
of GCE was 39.08 mg GA g–1, confirming its antioxidant
activity due to the polyphenolic compound [12]. These
results were close to those found by Siva, Rajikin [20].
They reported total phenolic contents of GCEs obtained
by isopropanol and methanol to be 30.65 mg GA g–1
and 16.26 mg GA g–1, respectively. Similarly, Naidu
et al. reported 32.19% and 31.71% for arabica and
robusta isopropanol/water extracts, respectively [21].
However, the total phenolic content of coffee depends
on its variety [6]. Bidchol et al. and Ballesteros et al.
also found that extracts of spent coffee grounds had
19.99 ± 3.56 mg 100 mL–1 chlorogenic acid and 350.28 ±
11.71 mg GAE 100 mL–1 [7, 12].
The most common polyphenols in coffee are
phenolic acids, mainly caffeic acid, a type of transcinnamic
acid, and its derivative, chlorogenic
acid [22]. Chlorogenic acid is able to directly interact
with reactive oxygen species (ROS), making it an
effective OH• scavenger [12]. However, the content of
chlorogenic acid in green coffee beans varies depending
on genes, species, climate, nutrient state of soil,
processing techniques such as decaffeination, degree
of ripeness, and also roasting. Since phenolic acid is
heat sensitive, green coffee beans have a higher content
of chlorogenic acid [8]. In addition, it was found that
coffee extract exhibited an antioxidant activity similar to
grapes and pomegranates [12].
Antioxidant activity. According to Table 1, the IC50
of GCE is 1.95 mg mL–1, which is higher than that of
Table 1 Total phenolic content and IC50 in green coffee extract
(GCE) and TBHQ
Sample Total phenol, mg GA g–1 IC50
GCE 39.08 1.95
TBHQ – 1.04
Figure 1 Oxidative stability of: (a) control, (b) GCE 1%
and (c) EGCE 5%
Time, h
(a)
Time, h
(b)
Time, h
(c)
μS/cm μS/cm μS/cm
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Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
TBHQ (1.04 mg mL–1). Based on the data, we calculated
the DPPH radical scavenging activity of GCE (74%) [23].
The high total phenolic content of GCE found in our
study confirmed its high radical scavenging activity
and antioxidant potential. In addition, the technique we
used and the coating material had a great impact on the
retention of phenolic compounds and antioxidant activity
of encapsulated samples [12].
Similar results were revealed by Naidu et al. who
reported 92, 87, and 76% antioxidant activity for
arabica and 88, 82, and 78% for robusta at 60:40, 70:30,
and 80:20 isopropanol/water ratios, respectively [21].
Jeszka-Skowron et al. also found that the antioxidant
capacities of arabica and robusta green coffee averaged
56.3% [24]. Interacting with DPPH, antioxidants
transfer an electron or a hydrogen atom to DPPH,
thus neutralizing its free radical character [25]. The
degree of discoloration indicates the scavenging
potential of the antioxidant extract. This radical
scavenging ability is mostly related to the types and
amounts of antioxidative components in the extract
and their ability to donate a hydrogen group [7].
The antioxidant constituents in green coffee are
chlorogenic, ferulic, caffeic, and coumaric acids [26].
Chlorogenic and caffeic acids are considered the most
relevant markers in coffee samples [27]. However,
other compounds such as caffeine, trigonelline, and
phenylalanines (formed during coffee roasting) have
antioxidant properties as well.
Oxidative stability. The oxidative stability curve
and the induction time for different treatments of kashk
samples are shown in Fig. 1.
As we can see, the longer the induction time, the
greater the oxidative stability. The induction time of the
control, GCE, and EGCE were 0.35, 0.58, and 0.43 h,
respectively. The kashk samples containing GCE (free
or encapsulated) showed a longer induction time than the
control due to GCE’s antioxidant activity. Noteworthily,
food products supplemented with extracts rich in
polyphenols have an increased antioxidant potential
[2, 4, 28]. However, encapsulation shortened induction
time, which was in contrast to [2, 29, 30]. Many studies
that used microencapsulation managed to avoid the
deterioration of unsaturated fatty acids by oxidation.
Indeed, the wall materials surrounded droplets and
protected them from environmental conditions [31–33].
As expected, canola oil is sensible to oxidation due to a
high amount of unsaturated fatty acids [34].
pH. According to Table 2, the initial pH of the
control was significantly higher than that of other
samples (P < 0.05). It decreased from 4.04 to 3.81 during
storage. However, the GCE kashk showed the reverse
trend for 30 days, followed by a pH decrease (P < 0.05).
We also found that higher GCE concentrations led to
higher pH of the samples, even at the end of the storage
period. According to Carvalho et al., the pH of GCE is
approximately 5.77–5.95 [31].
The acidity of all kashk samples containing
GCE microencapsules also increased throughout the
Table 2 pH of kashk samples supplemented with GCE during storage
Storage period, days
Sample 1 15 30 45 60
Control 4.04 ± 0.06aA 4.02 ± 0.04aB 3.98 ± 0.03aC 3.86 ± 0.07aD 3.81 ± 0.01aE
GCE 1% 4.02 ± 0.01bA 4.04 ± 0.02bB 4.06 ± 0.05bC 3.99 ± 0.06bD 3.94 ± 0.06bD
GCE 0.5% 3.98 ± 0.02cA 4.02 ± 0.03cB 4.04 ± 0.06cC 3.96 ± 0.05bD 3.91 ± 0.01bE
GCE 0.25% 3.95 ± 0.03dA 3.98 ± 0.07dA 4.01 ± 0.03dA 3.94 ± 0.01bB 3.88 ± 0.03cC
EGCE 5% 4.03 ± 0.06bA 4.05 ± 0.01bA 4.08 ± 0.01bA 4.01 ± 0.03bA 3.97 ± 0.01bB
EGCE 2.5% 4.00 ± 0.02cA 4.02 ± 0.02cA 4.05 ± 0.01cC 3.98 ± 0.01bA 3.92 ± 0.05bB
EGCE 1.25% 3.97 ± 0.08dA 4.00 ± 0.05dB 4.03 ± 0.06cC 3.95 ± 0.06bD 3.89 ± 0.07cE
Small letters in each column and capital letters in each row show a significant difference between samples (P < 0.05)
Results are reported as means ± SE, for three replicates of each sample
Figure 2 (a) Optical microscopy of EGCE (100×, 400×)
and (b) Droplet size distribution in initial emulsion
(a)
Diameter, μm
(b)
Frequency, μm
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Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
and 1.2% (w/v) had a positive effect on the fermentation
and survival of probiotic bacteria in milk and yoghurt.
According to Lee et al., the reduction of pH in all kashk
samples containing GCE microencapsules was related to
the production of lactic acid during storage [35].
Particle size distribution. The average particle size
of the initial emulsion droplets is presented in Fig. 2.
According to the curves, the droplets size was in the
range of 3.20 to 8.51 μm.
These results confirm a microscopic size of
encapsulated emulsion droplets. Particle size has a great
influence on such features as the surface oil and the final
content of the ultimate encapsulated powder [39]. For
instance, particles larger than 30 μm may create a sandy
Figure 3 Fourier transform infrared spectra of: (a) GCE 1% and (b) EGCE 5%
whole storage period, which was in agreement with
Lee et al. [35]. This phenomenon was due to the
production of lactic acid during storage. The activity
of lactic acid bacteria, hydrolysis, and lipid oxidation
resulted in lactic acid accumulation. Thus, the reduction
of pH occured [36].
On the other hand, increased acidity during storage,
called post-acidification, is attributed to the activity of
kashk starter cultures at refrigerated temperature. They
include Streptococcus thermophilus and Lactobacillus
delbruekii subsp. bulgaricus that produce small amounts
of lactic acid by fermenting lactose [37]. In addition, the
positive effect of GCE on probiotic bacteria found in
our study was confirmed by Marhamatizadeh et al. [38].
They reported that adding coffee extract at 0.4%, 0.8%,
(a)
(b)
CM-1
CM-1
%T %T
100
90
80
70
60
50
40
30
20
10
100
90
80
70
60
50
40
30
20
10
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
3371.81
2927.88
2557.14
1613.70
1390.92
1269.92 1050.96
1120.08
1157.98
991.36
616.80
764.15
814.57
853.28
610.25
673.95
762.48
745.80
815.65
852.92
991.88
1051.87
1119.57
1157.81
1391.53 1270.18
1651.53 1606.11
1698.14
2931.72
3329.02
45
Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
feel in the mouth. The average diameter of vegetable oil
droplets was 32 μm in the initial emulsion and 1–4 μm in
D-limonene primary emulsion [40, 41]. Our results were
in agreement with Karim et al. and Silva et al. [29, 31].
FTIR analysis. The average values of typical FTIR
spectra for GCE and EGCE are depicted in Fig. 3.
There, we can see characteristic broad low-frequency
absorption bands at 3371 and 3329 cm−1 respectively,
in the hydroxyl region (4000–3000 cm−1). These bands
represented the stretching vibrations of O–H in the
constituent sugar residues and adsorbed water [36]. We
also observed three sharp peaks in the range of 3000 to
2800 cm–1 (2927, 2931, and 2852 cm–1) for both arabica
and robusta roasted coffee samples, but no identification
was attempted. Nonetheless, FTIR analysis of caffeine
in soft drinks revealed two sharp peaks at 2882 and
2829 cm–1, which were attributed to the asymmetric
stretching of C-H bonds of methyl (-CH3) group in the
caffeine molecule and the peak region.
These findings were successfully used by Chemat
et al. to develop predictive models for quantitative
analysis of caffeine [42]. In their study, the wave number
in the region between 1400–900 cm–1 was identified
by vibrations of several types of bonds, including
C-H, C-O, C-N, and P-O. The stretching of the cis
= C-H and cis -C=C- at 1651 cm–1 was an indicator of
unsaturated fatty acids in vegetable oils [1]. Alcohols,
saturated aldehydes and α, β-unsaturated aldehydes
are major secondary oxidation products. In the region
between 1730–1680 cm–1, all aldehydes exhibit C=O
stretching bands [2]. It is evident that carbonyl stretching
around 1698 cm–1 may represent acetone [27]. The
disappearance of peaks at 2857 cm–1 and the appearance
of two peaks at 1698 and 1651 cm−1 in the EGCE
treatment was due to the presence of canola oil and
indicated well-encapsulated GCE.
Fatty acid composition. As can be seen in
Table 3, the samples containing encapsulated GCE
had a lower content of fatty acids than the others. The
results indicated the protective role of encapsulation
against the oxidation reaction. This finding was in
agreement with the results of Fantoni et al. and Sun-
Waterhouse et al. [19, 43]. In addition, EGCE treatment
provided higher amounts of linoleic, oleic, and elaidic
acids. The significant difference found in the contents
of oleic and linoleic acids was due to the presence of
canola oil in the encapsulated samples. Indeed, oleic
acid and linoleic acid are two main fatty acids found
in canola oil [44]. Dubois et al. claimed that oleic acid
is the principal ingredient of various vegetable oils,
including olive and rapeseed oils, and is a major dietary
monoenoic acid [45]. Among PUFAs (polyunsaturated
fatty acids), linoleic acid is the only one that reduces
LDL-cholesterol. Consequently, encapsulation of canola
oil has health benefits, as well as protective properties.
According to the fatty acid profile, the control had
a slightly higher content of total saturated fatty acids
than the GCE kashks, while the EGCE samples had the
lowest. The EGCE had the largest content of PUFAs and
MUFAs due to the presence of canola oil.
Rheological characteristics. The rheological parameters
of the three kashk samples (control, GCE 1%,
Table 3 Fatty acid composition of control, GCE 1%
and EGCE 5% kashks, %
Fatty acid Control GCE 1% EGCE 5%
Butyric acid 0.93 2.25 0.77
Caproic acid 0.63 3.97 1.78
Caprylic acid 1.51 4.26 1.65
Capric acid 4.37 3.67 3.83
Lauric acid 4.27 5.56 2.63
Myrisric acid 15.23 12.31 5.89
Myristoleic acid 1.34 1.24 0.54
Pentadecanoic acid 0.72 0.37 0.20
Palmitic acid 39.21 28.01 17.99
Palmitoleic acid 1.02 1.10 0.97
Margaric acid 0.68 0.50 0.35
Heptadecenoic acid 0.67 0.78 0.15
Stearic acid 3.24 2.26 2.02
Oleic acid (cis) 21.95 14.67 43.93
Elaidic acid (trans) 2.09 10.79 13.99
Linoleic acid (cis) 0.06 0.51 2.59
Behenic acid 0.06 0.42 0.05
100
Table 4 Effects of storage on some model parameters of control, GCE 1%, and EGCE 5% samples
Power Law Bingham Casson
Day Sample n k, Pa·sn r2 σ0 η, Pa·sn r2 k0C kc, Pa·sn r2
1 control 0.07 ± 0.00a 15.04 ± 0.15a 97.33 ± 0.15a 18.41 ± 0.07a 0.017 ± 0.00a 94.27 ± 0.40a 4.25 ± 0.01a 0.04 ± 0.00a 95.83 ± 0.25a
GCE 1% 0.07 ± 0.00a 14.94 ± 0.27a 97.10 ± 0.20a 18.36 ± 0.12a 0.017 ± 0.00a 93.80 ± 0.40a 4.24 ± 0.02a 0.04 ± 0.00a 95.50 ± 0.30a
EGCE
5%
0.07 ± 0.01a 14.72 ± 0.97a 96.90 ± 0.72a 18.25 ± 0.44a 0.018 ± 0.00a 93.33 ± 1.55a 4.22 ± 0.07a 0.04 ± 0.01a 95.16 ± 1.14a
60 control 0.06 ± 0.01a 15.29 ± 1.06a 97.30 ± 0.69a 18.51 ± 0.45a 0.016 ± 0.00a 94.23 ± 1.44a 4.26 ± 0.06a 0.04 ± 0.01a 95.83 ± 1.09a
GCE 1% 0.07 ± 0.03a 15.30 ± 2.36a 97.23 ± 1.49a 18.47 ± 0.99a 0.016 ± 0.01a 93.96 ± 3.28a 4.25 ± 0.14a 0.04 ± 0.02a 95.60 ± 2.36a
EGCE
5%
0.09 ± 0.01a 13.53 ± 0.71a 96.03 ± 0.60a 17.71 ± 0.34a 0.022 ± 0.00a 91.33 ± 1.35a 4.14 ± 0.05a 0.05 ± 0.01a 93.67 ± 1.01a
Results are reported as means ± SE, for three replicates of each sample
a P < 0.05
46
Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
Figure 4 Apparent viscosity of the kashk samples during
storage: (a) control; (b) GCE 1%; and (c) EGCE 5%
(b)
(c)
, ,
and EGCE 5%) on days 1 and 60 of the storage period
are presented in Table 4. We found no significant
differences in the viscosity of the treatments. As shown
in Fig. 4, the samples’ viscosity increased after 60 days
of storage. Noteworthily, post-acidification caused a
decline in the negative electric charge of casein micelles
by dissolving calcium and inorganic phosphate. It
attenuates colloidal stability and subsequently casein
becomes insoluble near its isoelectric pH (about 4.6).
This phenomenon, strengthening protein-protein
complexes and protein-polyphenol interaction, enhances
serum released from the gel matrix and, at the same
time, increases viscosity [46]. To explain the consistency
coefficient, flow index, and yield stress of the samples,
we used different rheological models, namely Power law,
Bingham, and Casson models. According to R2 of the
samples (higher than 0.97), the data fitted the Power Law
model more than the others (Table 4). As can be seen,
there were no significant differences in flow index values
between all the samples at the beginning and at the end
of storage (P > 0.05). The same trend was observed in
the other model parameters throughout storage.
According to the Power law equation, the kashks
containing GCE 1% and EGCE 5% had the highest and
the lowest consistency coefficient on the first day of
storage, respectively. At the end of storage, however, the
control and the EGCE 5% kashk had the lowest (0.064)
and the highest (0.090) flow index.
In Bingham’s equation, the control had the lowest
(0.016) and the EGCE 5% sample had the highest (0.018)
consistency coefficient at the beginning of storage. The
same trend was revealed on day 60. The highest yield
stress (18.51) was observed in the control and the lowest
(17.71) in the EGCE 5% kashk on day 60. Further, no
significant differences were seen among the samples.
The Casson equation showed the same trend at
the end of storage. However, we recorded the lowest
yield stress (4.14) in EGCE 5% and the highest (4.26)
in the control on day 60. Values within this range were
found in kashk with and without the addition of gum
tragacanth [1]. A higher consistency coefficient and
a lower flow index can be considered appropriate to
achieve a high viscosity and a clean mouthfeel [1].
Overall, all the samples showed a plastic-shear thinning
behavior because of lower flow index (n) values (< 1) and
a higher consistency coefficient.
Color. Table 5 summarizes the color characteristics
of the kashk samples supplemented with GCE on days 1
and 60.
Increasing the concentration of GCE (microencapsulated
or free) led to higher b* and L* values. We found
that the highest b* value was related to the brownish
yellow color of coffee extract. Among all the samples,
those incorporated with microencapsulated GCE had
higher b* and L* values compared with the others
(P < 0.05). The higher L* value might be due
to the reflection properties of lipid droplets or
microencapsulated particles.
In general, we noticed no differences in the
a* value of the kashk samples incorporated with GCE
(free or microencapsulated). The L* and a* values of all
the treatments increased throughout storage (60 days)
(P < 0.05). However, the b* value did not change
significantly in the microencapsulated GCE samples,
while increasing considerably in the control (P < 0.05)
due to the brownish yellow color of coffee extract. This
result was in agreement with the studies of Lee et al. and
Alavi et al. who reported enhanced L* and a* values in
yoghurt enriched with powder peanut sprout extract
microcapsules during 16 days [35, 36]. However, the
b* value remained almost unchanged.
Sensory analysis. Sensory attributes of the samples
were evaluated on the first and last days of storage
(Fig. 5).
We found significant differences between the color of
the kashk samples at the beginning (P < 0.05). The GCE
1% sample had a higher score, whereas the EGCE 0.25%
Days 1 Days 60
(a)
Shear rate, s–1
Apparent viscosity, Pa·s
Shear rate, s–1
Apparent viscosity, Pa·s
Shear rate, s–1
Apparent viscosity, Pa·s
280
240
200
160
120
80
40
0
3.84 23.04 42.24 61.44 80.64 99.84 119.04 138.24 157.44 176.64
360
300
240
180
120
60
0
3.84 23.04 42.24 61.44 80.64 99.84 119.04 138.24 157.44 176.64
3.84 23.04 42.24 61.44 80.64 99.84 119.04 138.24 157.44 176.64
280
240
200
160
120
80
40
0
47
Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
Table 5 Color characteristics of kashk samples with GCE on day 1 and day 60
Day 1 Day 60
Sample L* a* b* L* a* b*
Control 56.50 ± 0.50Bb –6.20 ± 0.21Ba 11.37 ± 0.70Bc 63.55 ± 0.09Ab –3.55 ± 0.19Ab 14.34 ± 0.95Aa
GCE 1% 55.06 ± 0.90Bc –6.18 ± 0.30Ba 12.30 ± 0.02Bb 69.68 ± 0.42Aa –2.22 ± 0.08Aa 13.62 ± 0.43Ab
GCE 0.5% 56.27 ± 0.85Bb –6.13 ± 0.54Ba 12.60 ± 0.32Bb 62.33 ± 0.14Ab –3.24 ± 0.11Ab 10.26 ± 0.15Bc
GCE 0.25% 54.41 ± 0.56Bb –6.08 ± 0.26Ba 11.44 ± 0.84Ac 62.37 ± 0.74Ab –4.85 ± 0.42Ac 11.65 ± 0.71Ac
EGCE 5% 57.44 ± 0.19Ba –6.71 ± 0.40Ba 13.57 ± 0.42Aa 62.24 ± 0.06Ab –2.24 ± 0.11Aa 13.22 ± 0.48Ab
EGCE 2.5% 56.72 ± 0.85Bb –6.51 ± 0.99Ba 12.37 ± 0.59Ab 60.34 ± 0.08Ac –3.12 ± 0.36Ab 11.97 ± 0.35Ac
EGCE 1.25% 55.42 ± 0.80Bc –6.95 ± 0.09Ba 11.61 ± 0.64Ac 60.55 ± 0.29Ac –4.34 ± 0.65Ac 11.25 ± 0.31Ac
Different small letters in each column and capital letters in each row show a significant difference between samples (P < 0.05). Results are
reported as means ± SE, for three replicates of each sample
Figure 5 Sensory attributes of kashk samples supplemented with GCE on day 1 and day 60: (a) Color; (b) Odor; (c) Taste;
(d) Consistency; (e) Total acceptability
had a lower score (P < 0.05). The color of all the samples
improved throughout storage. The GCE 1% had a better
score, which was attributed to the light greenish yellow
color of the coffee extract. However, it seems that GCE
encapsulation protected the color of the kashk samples.
As expected, the product with GCE 1% (free form) had
better odor, taste, consistency, and overall acceptancy
than the others.
Among all the samples, the EGCE 1.25% kashk
obtained a lower score (P < 0.05). As predicted, the odor
of kashk containing a free form of GCE improved with
the concentration increased. This finding confirms a
positive effect of GCE on kashk products. Nevertheless,
a decline in odor was observed during storage due to
the loss of some volatile compounds. We found that
the samples’ consistency improved with the extract
Day 1 Day 60
Sensory score
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
Day 1 Day 60
Sensory score
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
(b)
Day 1 Day 60
Sensory score
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
Day 1 Day 60
Sensory score
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
(d)
(e)
Day 1 Day 60
Sensory score
4.9
4.7
4.5
4.3
4.1
3.9
3.7
3.5
1
3
2
4 5
6
7
1 Control
2 GCE 1%
3 GCE 0.5%
4 GCE 0.25%
5 EGGE 5%
6 EGGE 2.5%
7 EGGE 1.25%
(a)
(c)
48
Rahpeyma E. et al. Foods and Raw Materials, 2020, vol. 8, no. 1, pp. 40–51
concentration (free form) increased. Overall, the kashk
fortified with GCE 1% was favored by the assessors,
possibly due to its oily appearance.
Nonetheless, the type of microencapsulation
technique influences the protective effects of odor/
flavor components. For instance, Rodrigues et al.
used cashew gum and Arabic gum as a wall material
for microencapsulation of coffee extract during
spray drying [47]. Both Arabic gum and cashew gum
had similar aroma protective effect and showed no
differences between the control and experimental
samples. Furthermore, there is some dependence
between the product’s sensory properties and the type
of herbal extract. Ribeiro et al. evaluated the color
parameter of cottage cheese incorporated with free and
encapsulated mushroom extract and revealed no changes
in cottage cheese color [16]. However, the samples’ color
improved after 7 days (P < 0.05). Also, Gurkan et al.
analyzed the taste and flavor characteristics of yogurt
enriched with basil (Ocimum basilicum L.) powder or
extract during three weeks of storage at 4°C [48]. They
identified 49 volatile compounds which enhanced the
sensory score of yogurts. The presence of some volatile
carboxylic acids gave yogurt an acceptable acidic taste.
CONCLUSION
We employed a W/O emulsion to encapsulate GCE
in kashk at different concentrations. Among all the
samples, the kashk incorporated with a high amount of
GCE had a higher pH. However, pH reduced throughout
storage due to the production of a small amount of
lactic acid. Furthermore, GCE possessed antioxidant
activity, mainly due to its high phenolic content, and the
samples containing GCE and EGCE had high oxidative
stability. In addition, we confirmed a protective effect of
encapsulation against the oxidation reaction. The EGCE
sample had higher contents of only three free fatty
acids (linoleic, oleic, and elaidic) due to the presence of
canola oil in its composition. The control had the highest
content of total saturated fatty acids.
The FTIR spectra indicated that the GCE was well
encapsulated. The rheological behavior of the samples,
a plastic-shear thinning behavior, fitted the Power
Law model more than the others. Since particles larger
than 30 μm may create a sandy feel in the mouth and
the emulsion droplets in our study had a micrometer
size lower than 30 μm, we could claim that the EGCE
kashk had the best texture. Adding GCE (free and
microencapsulated) to kashk affected its sensory
properties. The kashk with 1% of GCE was preferred
by the assessors. In addition, the coffee aroma was felt
at the end of storage, which is a positive effect of using
GCE in dairy products. Finally, GCE encapsulation
protected the color of the samples and the b* value
remained unchanged, while lightness (L*) increased.
Overall, using a W/O emulsion can be successfully
employed as a technique for GCE encapsulation in kashk
and the resulting product can be offered to consumers as
an alternative type of flavored dairy product.
ACKNOWLEDGEMENT
The authors thank the Department of Food Science
at Sarvestan Islamic Azad University for their great
assistance during the research. We did not receive any
specific grants from funding agencies in the public,
commercial or not-for-profit sectors.

1. Adam F, Abert-Vian M, Peltier G, Chemat F. “Solvent-free” ultrasound-assisted extraction of lipids from fresh microalgae cells: A green, clean and scalable process. Bioresource Technology. 2012;114:457-465. DOI: https://doi.org/10.1016/j.biortech.2012.02.096.

2. Aguiar J, Estevinho BN, Santos L. Microencapsulation of natural antioxidants for food application - The specific case of coffee antioxidants - A review. Trends in Food Science & Technology. 2016;58:21-39. DOI: https://doi.org/10.1016/j.tifs.2016.10.012.

3. Zain MZM, Baba AS, Shori AB. Effect of polyphenols enriched from green coffee bean on antioxidant activity and sensory evaluation of bread. Journal of King Saud University Science. 2018;30(2):278-282. DOI: https://doi.org/10.1016/j.jksus.2017.12.003.

4. Budryn G, Zaczynska D, Oracz J. Effect of addition of green coffee extract and nanoencapsulated chlorogenic acids on aroma of different food products. LWT - Food Science and Technology. 2016;73:197-204. DOI: https://doi.org/10.1016/j.lwt.2016.06.019.

5. Dziki D, Gawlik-Dziki U, Pecio L, Rozylo R, Swieca M, Krzykowski A, et al. Ground green coffee beans as a functional food supplement - Preliminary study. LWT - Food Science and Technology. 2015;63(1):691-699. DOI: https://doi.org/10.1016/j.lwt.2015.03.076.

6. Bisht S, Sisodia S. Coffea arabica: A wonder gift to medical science. Journal of Natural Pharmaceuticals. 2010;1(1): 58-62. DOI: https://doi.org/10.4103/2229-5119.73595.

7. Bidchol AM, Wilfred A, Abhijna P, Harish R. Free radical scavenging activity of aqueous and ethanolic extract of Brassica oleracea L. var. italica. Food and Bioprocess Technology. 2011;4(7):1137-1143. DOI: https://doi.org/10.1007/s11947-009-0196-9.

8. Chatterjee D, Bhattacharjee P. Comparative evaluation of the antioxidant efficacy of encapsulated and un-encapsulated eugenol-rich clove extracts in soybean oil: Shelf-life and frying stability of soybean oil. Journal of Food Engineering. 2013;117(4):545-550. DOI: https://doi.org/10.1016/j.jfoodeng.2012.11.016.

9. Ezhilarasi PN, Indrani D, Jena BS, Anandharamakrishnan C. Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality. Journal of Food Engineering. 2013;117(4):513-520. DOI: https://doi.org/10.1016/j.jfoodeng.2013.01.009.

10. Martins A, Barros L, Carvalho AM, Santos-Buelga C, Fernandes IP, Barreiro F, et al. Phenolic extracts of Rubus ulmifolius Schott flowers: characterization, microencapsulation and incorporation into yogurts as nutraceutical sources. Food and Function. 2014;5(6):1091-1100. DOI: https://doi.org/10.1039/c3fo60721f.

11. Silva PI, Stringheta PC, Teofilo RF, de Oliveira IRN. Parameter optimization for spray-drying microencapsulation of jaboticaba (Myrciaria jaboticaba) peel extracts using simultaneous analysis of responses. Journal of Food Engineering. 2013;117(4):538-544. DOI: https://doi.org/10.1016/j.jfoodeng.2012.08.039.

12. Ballesteros LF, Ramirez MJ, Orrego CE, Teixeira JA, Mussatto SI. Encapsulation of antioxidant phenolic compounds extracted from spent coffee grounds by freeze-drying and spray-drying using different coating materials. Food Chemistry. 2017;237:623-631. DOI: https://doi.org/10.1016/j.foodchem.2017.05.142.

13. Getachew AT, Chun BS. Optimization of coffee oil flavor encapsulation using response surface methodology. LWT - Food Science and Technology. 2016;70:126-134. DOI: https://doi.org/10.1016/j.lwt.2016.02.025.

14. Palupi NW, Praptiningsih Y. Oxidized tapioca starch as an alginate substitute for encapsulation of antioxidant from coffee residue. International Conference on Food, Agriculture and Natural Resources, Ic-Fanres 2015. 2016;9: 304-308. DOI: https://doi.org/10.1016/j.aaspro.2016.02.136.

15. Tran T, Green NL, Ghosh S, Rousseau D. Encapsulation of water-in-oil emulsion droplets within crystal spheroids. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2017;524:1-7. DOI: https://doi.org/10.1016/j.colsurfa.2016.12.054.

16. Ribeiro A, Ruphuy G, Lopes JC, Dias MM, Barros L, Barreiro F, et al. Spray-drying microencapsulation of synergistic antioxidant mushroom extracts and their use as functional food ingredients. Food Chemistry. 2015;188:612-618. DOI: https://doi.org/10.1016/j.foodchem.2015.05.061.

17. Golmakani MT, Rezaei K, Mazidi S, Razavi SH. γ-Linolenic acid production by Arthrospira platensis using different carbon sources. European Journal of Lipid Science and Technology. 2012;114(3):306-314. DOI: https://doi.org/10.1002/ejlt.201100264.

18. Fantoni CM, Cuccio AP, Barrera-Arellano D. Brazilian encapsulated fish oils: Oxidative stability and fatty acid composition. Journal of the American Oil Chemists Society. 1996;73(2):251-253. DOI: https://doi.org/10.1007/bf02523904.

19. Chang PR, Yu JG, Ma XF. Preparation of porous starch and its use as a structure-directing agent for production of porous zinc oxide. Carbohydrate Polymers. 2011;83(2):1016-1019. DOI: https://doi.org/10.1016/j.carbpol.2010.08.076.

20. Demirel Z, Yilmaz-Koz FF, Karabay-Yavasoglu UN, Ozdemir G, Sukatar A. Antimicrobial and antioxidant activity of brown algae from the Aegean sea. Journal of the Serbian Chemical Society. 2009;74(6):619-628. DOI: https://doi.org/10.2298/jsc0906619d.

21. Naidu MM, Sulochanamma G, Sampathu SR, Srinivas P. Studies on extraction and antioxidant potential of green coffee. Food Chemistry. 2008;107(1):377-384. DOI: https://doi.org/10.1016/j.foodchem.2007.08.056.

22. Alothman M, Bhat R, Karim AA. Antioxidant capacity and phenolic content of selected tropical fruits from Malaysia, extracted with different solvents. Food Chemistry. 2009;115(3):785-788. DOI: https://doi.org/10.1016/j.foodchem.2008.12.005.

23. Farah A, Donangelo CM. Phenolic compounds in coffee. Brazilian Journal of Plant Physiology. 2006;18(1):23-36. DOI: https://doi.org/10.1590/S1677-04202006000100003.

24. Jeszka-Skowron M, Stanisz E, De Pena MP. Relationship between antioxidant capacity, chlorogenic acids and elemental composition of green coffee. LWT - Food Science and Technology. 2016;73:243-250. DOI: https://doi.org/10.1016/j.lwt.2016.06.018.

25. Naik GH, Priyadarsini KI, Satav JG, Banavalikar MM, Sohoni DP, Biyani MK, et al. Comparative antioxidant activity of individual herbal components used in Ayurvedic medicine. Phytochemistry. 2003;63(1):97-104. DOI: https://doi.org/10.1016/s0031-9422(02)00754-9.

26. Yashin A, Yashin Y, Wang JY, Nemzer B. Antioxidant and antiradical activity of coffee. Antioxidants. 2013;2(4): 230-245. DOI: https://doi.org/10.3390/antiox2040230.

27. Brezova V, Slebodova A, Stasko A. Coffee as a source of antioxidants: An EPR study. Food Chemistry. 2009;114(3):859-868. DOI: https://doi.org/10.1016/j.foodchem.2008.10.025.

28. Sainsbury J, Grypa R, Ellingworth J, Duodu KG, De Kock HL. The effects of antioxidants and shelf life conditions on oxidation markers in a sunflower oil salad dressing emulsion (SOSDE). Food Chemistry. 2016;213:230-237. DOI: https://doi.org/10.1016/j.foodchem.2016.06.081.

29. Karim FT, Ghafoor K, Ferdosh S, Al-Juhaimi F, Ali E, Bin Yunus K, et al. Microencapsulation of fish oil using supercritical antisolvent process. Journal of Food and Drug Analysis. 2017;25(3):654-666. DOI: https://doi.org/10.1016/j.jfda.2016.11.017.

30. Ifeduba EA, Akoh CC. Microencapsulation of stearidonic acid soybean oil in complex coacervates modified for enhanced stability. Food Hydrocolloids. 2015;51:136-145. DOI: https://doi.org/10.1016/j.foodhyd.2015.05.008.

31. Carvalho AGS, Silva VM, Hubinger MD. Microencapsulation by spray drying of emulsified green coffee oil with two-layered membranes. Food Research International. 2014;61:236-245. DOI: https://doi.org/10.1016/j.foodres.2013.08.012.

32. Zhong JF, Yang R, Cao XY, Liu X, Qin XL. Improved physicochemical properties of yogurt fortified with fish oil/γ-oryzanol by nanoemulsion technology. Molecules. 2018;23(1). DOI: https://doi.org/10.3390/molecules23010056.

33. Robert P, Fredes C. The encapsulation of anthocyanins from berry-type fruits. Trends in foods. Molecules. 2015;20(4):5875-5888. DOI: https://doi.org/10.3390/molecules20045875.

34. Wang W, Waterhouse GIN, Sun-Waterhouse D. Co-extrusion encapsulation of canola oil with alginate: Effect of quercetin addition to oil core and pectin addition to alginate shell on oil stability. Food Research International. 2013;54(1):837-851. DOI: https://doi.org/10.1016/j.foodres.2013.08.038.

35. Lee Y-K, Al Mijan M, Ganesan P, Yoo S, Kwak H-S. The physicochemical properties of yoghurt supplemented with microencapsulated peanut sprout extract, a possible functional ingredient. International Journal of Dairy Technology. 2013;66(3):417-423. DOI: https://doi.org/10.1111/1471-0307.12047.

36. Alavi N, Golmakani MT. Improving oxidative stability of virgin olive oil by addition of microalga Chlorella vulgaris biomass. Journal of Food Science and Technology-Mysore. 2017;54(8):2464-2473. DOI: https://doi.org/10.1007/s13197-017-2689-2.

37. Chuyen HV, Nguyen MH, Roach PD, Golding JB, Parks SE. Microwave-assisted extraction and ultrasound-assisted extraction for recovering carotenoids from Gac peel and their effects on antioxidant capacity of the extracts. Food Science & Nutrition. 2018;6(1):189-196. DOI: https://doi.org/10.1002/fsn3.546.

38. Marhamatizadeh MH, Ehsandoost E, Gholami P. The effect of coffee extract on the growth and viability of Lactobacillus acidophilus and Bifidobacterium bifidum in probiotic milk and yoghurt. Journal of Food Biosciences and Technology. 2014;4(1):37-48.

39. Jafari SM, Assadpoor E, He YH, Bhandari B. Encapsulation efficiency of food flavours and oils during spray drying. Drying Technology. 2008;26(7):816-835. DOI: https://doi.org/10.1080/07373930802135972.

40. Fuchs M, Turchiuli C, Bohin M, Cuvelier ME, Ordonnaud C, Peyrat-Maillard MN, et al. Encapsulation of oil in powder using spray drying and fluidised bed agglomeration. Journal of Food Engineering. 2006;75(1):27-35. DOI: https://doi.org/10.1016/j.jfoodeng.2005.03.047.

41. Soottitantawat A, Bigeard F, Yoshii H, Furuta T, Ohkawara M, Linko P. Influence of emulsion and powder size on the stability of encapsulated D-limonene by spray drying. Innovative Food Science & Emerging Technologies. 2005;6(1):107-114. DOI: https://doi.org/10.1016/j.ifset.2004.09.003.

42. Chemat F, Rombaut N, Sicaire AG, Meullemiestre A, Fabiano-Tixier AS, Abert-Vian M. Ultrasound assisted extraction of food and natural products. Mechanisms, techniques, combinations, protocols and applications. A review. Ultrasonics Sonochemistry. 2017;34:540-560. DOI: https://doi.org/10.1016/j.ultsonch.2016.06.035.

43. Sun-Waterhouse D, Zhou J, Miskelly GM, Wibisono R, Wadhwa SS. Stability of encapsulated olive oil in the presence of caffeic acid. Food Chemistry. 2011;126(3):1049-1056. DOI: https://doi.org/10.1016/j.foodchem.2010.11.124.

44. Mir Z, Goonewardene LA, Okine E, Jaegar S, Scheer HD. Effect of feeding canola oil on constituents, conjugated linoleic acid (CLA) and long chain fatty acids in goats milk. Small Ruminant Research. 1999;33(2):137-143. DOI: https://doi.org/10.1016/s0921-4488(99)00016-4.

45. Dubois V, Breton S, Linder M, Fanni J, Parmentier M. Fatty acid profiles of 80 vegetable oils with regard to their nutritional potential. European Journal of Lipid Science and Technology. 2007;109(7):710-732. DOI: https://doi.org/10.1002/ejlt.200700040.

46. Donmez O, Mogol BA, Gokmen V. Syneresis and rheological behaviors of set yogurt containing green tea and green coffee powders. Journal of Dairy Science. 2017;100(2):901-907. DOI: https://doi.org/10.3168/jds.2016-11262.

47. Rodrigues RAF, Grosso CRF. Cashew gum microencapsulation protects the aroma of coffee extracts. Journal of Microencapsulation. 2008;25(1):13-20. DOI: https://doi.org/10.1080/02652040701725486.

48. Gurkan H, Hayaloglu AA. Volatiles and sensory characteristics of yogurt manufactured by incorporating basil (Ocimum basilicum L.). International Journal of Food Properties. 2017;20:S779-S789. DOI: https://doi.org/10.1080/10942912.2017.1311344.