The survival of probiotic bacteria and sensory properties of yogurt affected by microencapsulation with resistant starch

Probiotics are live microorganisms, which transit the gastrointestinal tract and their benefits to the health can be achieved through the consumption of dairy products. In this study, the survival and effect of the probiotic bacteria (Lactobacillus casei) in the free and capsulated form in yogurt were aimed to investigate. Two types of yogurt were prepared by free and induced sodium alginate with 2% starch encapsulated Lactobacillus casei. The bacterial survival, acidity and sensory attributes were analyzed during storage for 20 days at the refrigerated condition (4˚C). Titration of acidity in yogurt with free L.casei cells was higher compared to yogurt containing encapsulated L.casei cells. The viable cell count of L.casei in free form for yogurt production was 2.3×108 CFU/ml at inoculation time and 107CFU/g after incubation at 42˚C to reach pH 4.5. When L.casei was encapsulated in sodium alginate beads, the probiotic survival raised at a rate of 1.05 log CFU/g during the same period of storage due to protection by microencapsulation. The results of sensory indices and eventually total score for each sample confirmed the lack of tangible impact by adding encapsulated bacteria in taste, appearance, oral and non-oral tissues. Final scores of probiotic yogurt samples containing free and encapsulated L.casei were not statistically different (p>0.05). The results indicated that encapsulation with sodium alginate can significantly increase the survival rate of probiotic bacteria in yogurt compared to probiotic yogurt over an extended shelf life.