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Content may be subject to copyright.
Pakistan Journal of Nutrition 10 (10): 955-958, 2011
ISSN 1680-5194
© Asian Network for Scientific Information, 2011
Corresponding Author: M. Khaskheli, Department of Animal Products Technology, Faculty of Animal Husbandry and Veterinary
Sciences, Sindh Agriculture University, Tandojam, Sindh, Pakistan
955
Production and Evaluation of Yoghurt Ice Cream
A.S. Mangsi , A.H. Soomro , M.H. Baloch , M. Khaskheli , A.H. Nizamani and G.B. Khaskheli
1 2 3 1 4 1
Department of Animal Products Technology, Institute of Food Sciences and Technology,
1 2
Department of Livestock Management, Department of Animal Breeding and Genetics,
3 4
Sindh Agriculture University, Tandojam, Sindh, Pakistan
Abstract: Yoghurt ice cream was prepared from buffalo milk using conventional ice cream-making technique.
A total of three trials (six batches in each) were conducted and analyzed for chemical characteristics and
sensory attributes. Total Solids (TS) content of yoghurt ice cream averaged 32.79±0.64%, protein content
5.18±0.16%, fat content 4.84±0.10% and ash content 1.06±0.08%. The overall mean score rated by panelists
for appearance/color was 3.68±0.08, for taste/flavor 39.63±0.71, for body/texture 25.50±0.42 and for melting
quality 3.56±0.13 from a total score of 5, 45, 30 and 5, respectively. The overall average meltdown rate of
yoghurt ice cream for 10 min was 15.76±1.48%, for 20 min 40.49±2.03%, for 30 min 65.72±1.95%, for 40 min
83.12±1.42% and for 50 min 93.19±1.26%. Sensory characteristics of yoghurt ice cream were gradually
improved after 1 month and 3 months storage period and perceived the better score among sensory space
map. Stored (3 months) yoghurt ice cream comparatively perceived the highest score for appearance/color
(4.45±0.08), taste/flavor (44.11±0.18), body/texture (28.78±0.16) and melting quality (4.61±0.13) followed by
one month stored (4.38±0.10, 43.67±0.22, 28.00±0.28 and 4.55±0.14, respectively) and fresh yoghurt ice
cream (3.68±0.08, 39.63±0.71, 25.55±0.42 and 3.56±0.13, respectively) from a total score of 5, 45, 30 and
5, respectively. Sensory properties of yoghurt ice cream discriminated the product with attractable
appearance/color, acceptable/palatable flavor and better body/texture.
Key words: Yoghurt ice-cream, production, evaluation, storage
INTRODUCTION
Ice cream is a palatable and highly nutritious food,
prepared from the buffalo and cow milk or combination
of the both, the other ingredients are cane sugar,
dextrose, fruit juices, preserved fruit, nuts, chocolate,
edible flavor and permitted food colors. Ice cream
production is rapidly developing technology that has
become a profitable industry because of recent
advances. Diverse ingredients and methods of freezing
have resulted in 240 different types of ice cream (Guven
and Karaca, 2002). Many under-nourished individuals
are deficient in lactase and cannot tolerate appreciable
quantities of milk or milk solids. Many who suffer lactose
intolerance mistakenly believe that they must avoid all
dairy products. The conversion of milk to yoghurt should
make it possible for these groups to consume
appreciable quantities of milk with minimal symptoms of
lactose intolerance due to reduction in lactose
(approximately 30%) during fermentation (Chandan and
Shahani, 1993). Yoghurt is an excellent food that is easy
to digest and is of high biological value and is known to
lower cholesterol levels (Guven and Karaca, 2002). The
use of yoghurt instead of milk decreased the viscosity of
ice cream mix and over-run capacity of ice cream (Guner
et al., 2007). However, mixing ice-cream mix and yoghurt
offers sensory and physical properties that are similar to
those of ice cream and yoghurt (EL-Nagar et al., 2002).
No scientific work has been done in any aspects on
yoghurt ice cream in Pakistan, thus aim of present study
was to produce and evaluate the quality characteristics
of yoghurt ice cream.
MATERIALS AND METHODS
A total of three trials (six batches in each) were
conducted to produce yoghurt ice cream from buffalo
milk using conventional ice cream-making technique at
the Department of Animal Products Technology. Buffalo
milk procured from Livestock Experiment Station, Faculty
of Animal Husbandry and Veterinary Sciences, Sindh
Agriculture University, Tandojam, was used during the
experimental trials.
Preparation of starter culture: Artisan starter culture
was prepared by fermenting the buffalo milk with natural
yoghurt culture and purified by re-culturing it several
times. The purified culture was maintained during the
experimental period.
Preparation of yoghurt: Milk was pasteurized (90°C) for
5 min and cooled to 45±1°C using running tap water.
Afterwards, it was inoculated with 2.5% artisan yoghurt
starter culture and incubated at 40±1°C (~3 hrs) till pH of
milk base decreased to 4.7.
Pak. J. Nutr., 10 (10): 955-958, 2011
956
Preparation of ice mix: Ice cream mix was prepared as
described by Guner et al. (2007). It was formulated as:
15% sugar and 0.1% gelatin added with whole buffalo
milk (70% of total amount of ice cream mix). The mixture
was heated (90°C) for 5 min and then cooled to 45±1°C.
Shortly after the yoghurt reached at desired level of pH,
it (30% of total amount of ice cream mix) was mixed with
ice cream blend.
Freezing of yoghurt ice-cream mix: Ice-cream mix was
transferred to conventional electrical ice-cream machine
and frozen for~20 min. The frozen yoghurt ice-cream was
transferred to a freezer (-18±2°C) for hardening and
subsequently it was stored till further analysis.
Analysis: Total solids, protein, fat and ash contents of
yoghurt ice-cream were analyzed according to methods
as described by Association of Official Analytical
Chemists (AOAC, 2000).
Sensory quality of yoghurt ice-cream (fresh and
stored): Sensory attributes of yoghurt ice-cream (fresh
and stored) were evaluated according the scheme of
Nelson and Trout (1981). The sensory panel comprising
of 6 judges were selected and they were first
experienced with various sensory attributes like
appearance/color, flavor, body/texture and melting quality
of the product i.e. (yoghurt ice-cream) and thereafter
samples were served to rate the score.
Meltdown rate: Meltdown rate was determined
according to the method of Guner et al. (2007). Yoghurt
ice-cream (100 g) after freezing at-18±2°C was placed
on a wire filter and fixed onto a beaker (24°C). The
weight of melted material was measured at 10th, 20th,
30th, 40th and 50th min and expressed as percentage
weight melted.
RESULTS AND DISCUSSION
In the present study some preliminary trials were
performed to produce yoghurt ice cream from buffalo
milk and yoghurt as a basic ingredient for the mix with
ratio of 1:3, 1:1, 3:1 and 2:1, respectively. Some
difficulties were experienced during initial trials.
However, it was successfully produced as acceptable
product from mix containing 70% buffalo milk and 30%
yoghurt with addition of 15% sugar and 0.1% gelatin.
Similar studies were conducted by El-Nagar et al.
(2002), who produced ice-cream from stirred yoghurt
blended with ice-cream pre-mix (1:1) and frozen in a
batch-top ice cream maker, whereas, Caisip and
Resubal (2001) and Jaswinder et al. (2006) prepared
yoghurt ice cream by direct inoculation of aged ice-
cream mix with starter culture prior to freezing. While
Guner et al. (2007) produced it from mix blended with21.5 to 28.50 (mean, 25.50±0.42) and 2.50 to 4.50
74.3% yoghurt.
Table 1: Chemical characteristics (%) of yoghurt ice cream
Descriptive measures
---------------------------------------------------
Characteristics Min. Max. Mean ±SE
Total solids content (%) 30.17 38.41 32.79 0.64
Protein content (%) 4.46 6.25 5.18 0.16
Fat content (%) 4.00 5.40 4.84 0.10
Ash content (%) 0.79 2.29 1.06 0.08
Min. = Minimum; Max. = Maximum
Chemical characteristics: Results shown in Table 1
revealed that total Solids Content (TS) of yoghurt ice-
cream was in between 30.17 and 38.41% and averaged
in concentration of 32.79±0.64%. The result of the
present study is consistent with the findings of El-Owni
and Zeinab (2009), who observed relatively the similar
TS content of ice cream i.e. in between 31.82 to 33.41%.
However, Jaswinder et al. (2006) found a significant
decrease in TS content of ice cream mix when yoghurt
base was added to it.
Protein content of yoghurt ice cream was found to be in
a range between 4.46 and 6.25% with the mean value of
5.18±0.16% (Table 1). The present findings are not in
agreement with the results of Emata et al. (2001) who
reported 3.72% protein content in low fat yoghurt ice
cream. Similarly, the results of present investigation are
also higher than the findings of El-Owni and Zeinab
(2009) who reported the range of protein content in
between 2.49 and 2.69%. It is of interest to note that in
the present study, the concentration of protein in yoghurt
ice cream was remarkably higher than that of observed
by the different researchers (Emata et al., 2001; El-Owni
and Zeinab, 2009). This could have been attributed with
the formulation of ice cream mix in which buffalo milk
was used as dairy base for the mix and assumed to
contain higher percentage of protein.
The fat content of yoghurt ice cream was in between 4.00
and 5.40% with an average of 4.85±0.10% (Table 1). The
result of present study was not in agreement with
findings of Inoue et al. (1998) who reported >8.0% fat
content in ice cream type frozen yoghurt. However, it was
relatively similar in fat content to that of light class (5%
fat) vanilla ice cream produced by Aimee et al. (2001).
The ash content of yoghurt ice cream was observed in
between 0.79 and 2.29% with an average of
1.06±0.08%. These results are not in consistent with the
findings of other reported work i.e. in between 0.39 to
0.64% (El-Owni and Zeinab, 2009).
Sensory evaluation: Yoghurt ice cream was evaluated
by panel of judges for sensory attributes like
appearance/color, flavor, body/texture and melting
quality. The score rated was in a range of 3.00 to 4.50
(mean, 3.68±0.08), 32.00 to 43.00 (mean, 39.63±0.71),
(mean, 3.56± 0.13) among a total score of 5, 45, 30 and
Pak. J. Nutr., 10 (10): 955-958, 2011
957
Table 2: Sensory evaluation (score) of yoghurt ice cream
Descriptive measures
---------------------------------------
Sensory attributes Min. Max. Mean ±SE
Appearance/color (Max. Score 5) 3.00 4.50 3.68 0.08
Taste/flavor (Max. Score 45) 32.00 43.00 39.63 0.71
Body/texture (Max. Score 30) 21.50 28.50 25.50 0.42
Melting quality (Max. Score 5) 2.50 4.50 3.56 0.13
Min. = Minimum; Max. = Maximum
Fig. 1: Trend of meltdown rate (%) of yoghurt ice cream
5 for appearance/color, flavor, body/texture and melting
quality, respectively. It was observed that there was no
remarkable effect of yoghurt on the above said sensory
attributes of the final product. Similar results of sensory
scores of yoghurt ice cream produced from the yoghurt
at 0.7% lactic acid were observed when compared with
the control group (Guner et al., 2007). While the score of
sensory attributes of flavor, body and texture and overall
acceptability differed significantly in yoghurt ice cream
prepared with yoghurt organisms (1:1) using (a)
blending yoghurt (15-60%) with ice cream mix prior to
freezing and (b) by direct inoculation of aged ice cream
mix with yoghurt culture (2-4%) followed by incubation
prior to freezing (Jaswinder et al., 2006). In another study
no "acidic-yoghurt taste" was observed in yoghurt ice
cream (Caisip and Resubal, 2001). Emata et al. (2001)
given the preference to yoghurt ice cream with one hour
and thirty minutes incubation period and rating scores
were like moderately to like very much in terms of the
flavor, aroma, color and appearance, body and texture
and general acceptability.
Meltdown rate: On an average, 93.19% of yoghurt ice
cream samples were melted within a time of 50 min
(Fig. 1). Whereas, Dogruer et al. (2004) reported that the
complete melting time of ice cream was in between
38.41 to 40.71 min. Guner et al. (2007) reported that
there was no negative effect of yoghurt on the melting
characteristics of ice cream. The use of yoghurt at 0.7%
lactic acid exhibited a good first drop (beginning of the
melting point) and melting time, but it was not
statistically significant. While Guven and Karaca (2002)
reported that there was an increase in the first dripping
Table 3: Sensory quality (score) of fresh and stored yoghurt ice
cream
Sensory attributes
Storage -----------------------------------------------------------------------------
period A/C T/F B/T MQ
Fresh 3.68±0.08 39.63±0.71 25.55±0.42 3.56±0.13
b b b b
1 month 4.38±0.10 43.67±0.22 28.00±0.28 4.55±0.14
a a a a
3 month 4.45±0.08 44.11±0.18 28.78±0.16 4.61±0.13
a a a a
±SE 0.18 0.52 0.61 0.20
LSD (0.05) 0.38 1.07 1.26 0.41
Means followed by different letters (a,b) within same column are
significantly different from one another, A/C = Appearance/color (Max.
Score 5), T/F = Taste/flavour (Max. Score 45), B/T = Body/texture (Max.
Score 30), MQ = Melting quality (Max. Score 5)
time period and complete melting times decreased in
parallel with the increase in sugar content and fruit
concentration of ice cream produced from yoghurt. El-
Nagar et al. (2002) found a clear relationship between
increased oligosaccharide levels and improved melting
properties of yoghurt ice cream. While Muse and Hartel
(2004) reported the effect of fat destabilization, ice crystal
size and consistency coefficient of mix melting rate of ice
cream.
Storage quality:The storage quality of yoghurt ice cream
was evaluated as difference of sensory scores among
the fresh, 1 month and 3 months stored samples. The
fresh yoghurt ice cream perceived the score with
average of 3.68±0.08, 39.63±0.71, 25.55±0.42 and
3.56±0.13 for appearance/color, flavor, body/texture and
melting quality, respectively and after one month period
of time, the score significantly (P<0.05) increased to
4.38±0.10, 43.67±0.22, 28.00±0.28 and 4.55±0.14,
respectively; whereas after 3 months of storage the
average score was 4.45±0.08, 44.11±0.18, 28.78±0.16
and 4.61±0.13, respectively. Similarly Jaswinder et al.
(2006) reported that yoghurt ice cream prepared by
blending of yoghurt (15-60%) with ice cream mix prior to
freezing and/or by direct inoculation of aged ice cream
mix with yoghurt culture (2-4%) followed by incubation
prior to freezing, was acceptable up to 40 days of
storage at -18±3 C. Inoue et al. (1998) reported that no
o
appreciable change in the structure, acidity and pH
values of ice cream type frozen yoghurt stored for six
months at -35 C.
o
Conclusion: On the basis of chemical characteristics
particularly the fat content (~5%), the yoghurt ice cream
was found to be as light ice-cream. While sensory
Pak. J. Nutr., 10 (10): 955-958, 2011
958
properties discriminated the product with attractableEl-Owni, O.A.O. and K.O.K. Zeinab, 2009. Chemical
appearance/color, palatable taste/flavor and better
body/texture. Meltdown rate was moderate. Storage (up
to 3 months) quality was gradually improved and
perceived the better score among sensory space map.
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