Probiotic viability and sensory properties of ice-cream supplemented with encapsulated Lactobacillus bulgaricus

Abstract

The aim of the research is to study the encapsulation method that being used to protect probiotic bacteria Lactobacillus bulgaricus (Lb) in ice cream for a period of 90 days of storage at -20 °C. Three different formulations have been developed i.e. Formulation A (FA, mixtures with gelatin 0.1%), Formulation B (FB, mixtures with gelatin 0.3%) and Formulation C (FC, mixtures with gelatin 0.5%). All statistical analysis has been reported at p<0.05. It was found that the microencapsulation or coating of L.bulgaricus significantly influenced their survivality compared to uncoated probiotic. Formulation B with coated Lb (FB.3) showed the highest viability which achieved 108.34 cfu/g. FB.3 showed the best outcome in terms of the quality factor measurements i.e. dry matter, fat, moisture content, viscosity which are 34.50 ± 0.89%, 7.66 ± 0.07%, 65.50 ± 0.89%, 125,000 ± 0.00 mPa.s respectively, and the size range of beads from 0.8 to 1.0 mm within the accepted level. At the end of 90 days storage at -20°C, the viability of the coated cells in formulation B are still within the accepted level with 2.2 x 108 cfu/g population which remained above 106 cfu/g. There are significant increase in viscosity with increased gelatin levels similarly with moisture content. Meanwhile dry matter significantly reduced in coated probiotic compared to uncoated in all of the ice-cream samples but protein showed remarkable reduction in FA and FB only. Sample FB showed significant reduction (p<0.05) on melting rate and viscosity. The highest fat content in FB gave the highest viability as compared to FA and FC. From the sensory evaluation towards probiotic flavour and acidic flavour, the overall panel rank for the highest acceptance is in Formulation A with coated Lb (FA.3) as compared to uncoated probiotic ice-cream i.e Formulation A with uncoated Lb (FA.2); Formulation B with uncoated Lb (FB.2) and Formulation B with coated Lb (FB.3). Furthermore, there are significant differences (p<0.05) between non probiotic ice-cream and probiotic ice-cream for all sample in terms of probiotic flavour and acidic flavour. Based on defined cooked flavour, probiotic flavour, and acidic flavour, there was a remarkable overall acceptance on the ice cream with coated probiotic. Meanwhile, acceptance upon uniformity of the ice cream based on colour and appearance showed more variation among the sensory panels. It can be concluded that the microencapsulation had good effect on sensorial acceptability (p>0.05) of probiotic ice cream. The results indicate that dairy ice cream can be considered a suitable vehicle for incorporating coated probiotic microorganisms for higher survival and better sensorial acceptance.