Vol 3 (1) 2011 - UBM :: Departamentul de Chimie-Biologie

M. Ayaz Javed, M. Nadeem, Development of probiotics ice cream in Pakistan from buffalo milk by using
B. bifidum and L. acidophilus
resistance as compared to L. acidophilus.
These results might be due to less acid
production property of B. bifidum. The
melting resistance of ice cream was
decreased by increasing concentration of
bacteria. Kebary [15] Studied the viability of
B. bacterium bifidum and its effect on
quality of frozen Zabady (frozen dessert)
and reported that all the samples had nearly
the same melting resistance.
L. acidophilus and B. bifidum both were able
to grow and produce acid during
fermentation in ice cream mix (Hekmat and
McMahon [16]. At 0 day (-18 ºC), 0 day the
total number of colonies counted were 10 5
cfu/ml in ice cream samples inoculated with
treatment T1, T4 and 10 6 in case of T7.
Treatments T2, T5 and T8 showed
comparatively better colonies i.e., 10 8
cfu/ml. T3, T6 and T9 showed maximum
number of bacteria i.e., 10 9 cfu/ml. The
probiotic culture added in combination i.e.
treatments T7, T8 and T9 showed results
close to treatments having single culture.
The reason might be nutrients competency
for both bacteria. Nutrients requirements for
B. bifidum is more than L. acidophilus [17].
Storage at -18ºC showed gradual decrease in
number of bacteria. First reduction was
observed after 45 days. There was total
reduction of approximately 3 log cycles in
case of L. acidophilus whereas, viability loss
was observed only 1 log cycle for
Bifidobacterium bifidum in the total
experimental duration of ninety days.
Hekmat and McMahon [16] observed in
their studies that the viability of L.
acidophilus in a standard ice cream mix
decreased by 2 log cycles after storage for
17 weeks at -29 ºC. In addition to that, more
viability loss was observed in case of L.
acidophilus which may be due to its more
acid production property than Bifidum. The
decline in viable bacterial count during
freezing step is most likely to be due to
actual freezing of the cells that caused death
of some cells. However, the mechanical
stresses of the mixing and freezing processes
and also oxygen incorporation into mix may
have resulted reduction in viable bacterial
count. Similar results were reported by
earlier studies [18, 19, 20]. It was also
observed that after 15 and 45 days of storage
no decrease was found in viable count.
However, a decrease in viable count was
observed during 45 to 90 days of storage at -
18 ºC, present study can be concluded as ice
cream can serve as a good mean for
delivering probiotic bacteria to the
consumer. B. bifidum and L. acidophilus
exhibited approximately similar properties.
Level of probiotic bacteria used in treatment
T3, T5 and T6 was found more appropriate
in making ice cream a probiotic food
product. B. bifidum was found better in
maintaining viable count i.e., 10 6 to 10 7
cfu/ml at the time of consumption after three
months. Its survival rate was maximum
among all treatments (89.09%).
3.2.Effect on sensory attributes of ice cream
The results depicted in Table 3
represent the organoleptic attributes of ice
cream as adjudged by a panel of five judges
in terms of color, taste, surface spots,
thickness and overall acceptability. It is
evident from statistical analysis of score
obtained, that various treatments did not
impart any significant difference on color of
probiotic ice cream. Color plays an
important role in making a food product
appealing and eatable for the consumer.
Parameter of surface spot was studied to
check any impression, secretion, mark or
spot produced by probiotic bacteria added in
ice cream. No sign for colony growth and
spots of any kind was found on surface of
ice cream which indicated more acceptance
of the product. It means both bacteria have
excellent capability of addition in ice cream.
Increased levels of bacteria had a negative
effect on thickness of ice cream. The low
scores of thickness of T 1 , T 2 , T 3 , T 6 , T 7 , T 8
and T 9 and may be attributed to the more
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