Development of Microencapsulated Probiotic Ice Cream
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Date
2014
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
A study was undertaken to microencapsulate four different probiotic strains viz., Bifidobacterium
animalis ssp. lactis (BB-12), Lactobacillus acidophilus (LA-5), Lactobacillus casei (NCDC-298) and
Lactobacillus reuteri-(ATCC-55730) and incorporate into the ice cream. Microencapsulation was done by
two different methods (extrusion and emulsion) using two different combination of wall materials viz.,
sodium alginate + starch and sodium alginate + starch + whey protein concentrate. Five different lots of
probiotic ice creams were prepared for each of the probiotic culture. The unencapsulated probiotic ice
cream and encapsulated probiotic ice cream were designated as UPI and EPI and the four above
mentioned probiotic strains were denoted as A, B, C and R (being the first letter of the respective species)
respectively. Accordingly, the samples of unencapsulated probiotic ice cream (Treatment I) were denoted
as UPIA-I, UPIB-I, UPIC-I and UPIR-I. The treatment II (extrusion- sodium alginate + starch ) and
treatment III (extrusion- sodium alginate + starch+whey protein concentrate ) samples of ice cream
containing the above mentioned four different encapsulated probiotic strains were denoted as EPIA-II,
EPIB-II, EPIC-II, and EPIR-II and EPIA-III, EPIB-III, EPIC-III and EPIR-III respectively. Similarly,
treatment IV (emulsion- sodium alginate + starch ) and treatment V (emulsion- sodium alginate + starch+
whey protein concentrate ) were designated as EPIA-IV and EPIB-V, EPIC-IV, and EPIR-IV and EPIAV,
EPIB-V, EPIC-IV and EPIR-V respectively.
The developed ice cream samples containing encapsulated probiotics were subjected to physicochemical
analysis, analysis of textural properties, organoleptic evaluation, survivability of the probiotic
cultures in ice cream during storage period and in vitro viability in simulated gastric and intestinal
conditions.
Beads with minimum diameter were produced with the use of insulin syringe. Size of the
emulsion beads was lower when the emulsifier percentage was less (0.5%). Speed of addition of CaCl2
solution affected bead shape. SEM analysis of beads revealed characteristic size, shape and structure of
the beads. The size of the beads got reduce when stored in the CaCl2.
On comparison of viability of different encapsulated probiotics strains by extrusion method
(Treatment -II and Treatment-III) during different storage periods, it is found that encapsulation of L.
acidophilus (LA-5) showed significantly higher viability after 60 days of storage followed by L. casei
(NCDC-298). Though there was enhanced viability due to encapsulation, in comparison with the above
mentioned strains, B. lactis (BB-12) and L. reuteri (ATCC-55730) strains showed lower viability.
The viability studies of encapsulated probiotics by emulsion method (Treatment-IV and
Treatment-V) showed better viability during storage period. It is observed that, microencapsulated L.
acidophilus in both the treatments EPIA-IV and EPIA-V (LA-5) showed better viability of above 7 log
units at the end of 120 days of storage followed by L.casei (NCDC-298). Similar to that of extrusion
method, B.lactis (BB-12) and L reuteri (ATCC-55730) strains showed lower viability when compared
with other two strains.
During the in-vitro viability study of probiotics encapsulated by extrusion method (Treatment-II
and Treatment-III) in simulated gastric fluid (SGF), it is found that except B.lactis (BB-12), all other
probiotic strains survived at least 7 log units after 120 min of incubation in SGF. Further, it is inferred
that, treatment-III showed better survivability after 120 min of incubation in SGF.
Similarly, in the in vitro viability study of probiotics encapsulated by emulsion method
(Treatment-IV and Treatment-V) in simulated gastric fluid, L. acidophilus (LA-5) and L. casei (NCDC-
298) showed better survivability of at least 7 log units at the end of 120 minutes of incubation. Among the
emulsion methods, treatment-V gave improved viability when compared to treatment -IV. In treatment-V,
all probiotic strains except B.lactis (BB-12) showed better viability of more than 7 log unit up to the end
of 90 minutes of incubation in SGF and also L.acidophilus (LA-5) and L. casei (NCDC-298) which
showed the required viability of at least 7 log units at the end of 120 minutes of incubation in SGF.
During the viability study in simulated gastro intestinal conditions, it was observed that
L.acidophilus (LA-5) and L.casei (NCDC-298) showed better viability in all four treatments. Among the
treatments, treatment-III showed higher viability throughout the study.
The different treatments of both unencapsulated and encapsulated probiotic ice creams showed
relatively low reduction in pH when compared with the control. However, in case of ice cream mix there
was no differences observed with regard to pH and titratable acidity between control and other treatments.
The whipping ability of unencapsulated and encapsulated probiotic ice creams showed no significant
differences between control, unencapsulated and encapsulated treatments and also there were no
differences observed between different treatments of ice cream in the overrun.
In different treatments of unencapsulated and encapsulated probiotic ice cream, there was no
significance difference observed with regard to meltdown time at a particular storage period and the mean
value of meltdown time was gradually increased as the storage period increased.
There was no significant changes observed in coliform count between the treatments in a
particular period of storage but during different period of storage there was a reduction in count observed.
Regarding common textural properties and hardness, a significant difference was observed between
different treatment ice cream and control but this differences did not influence negatively on the sensory
properties of the product as there was no significant difference observed in the sensory evaluation
between control and other treatments.
It was concluded that survivability of probiotics in ice cream can be significantly improved by
microencapsulation technique. Among all the treatments, the treatment-III (extrusion- sodium alginate +
starch+whey protein concentrate) showed best viability for all the probiotic strains and during different
environmental condition without altering physico-chemical, textural and sensory properties.