The effects of addition of sodium caseinate and microencapsulation process on the viability of Lactobacillus acidophilus and qualitative properties of probiotic yoghurt during storage

Yogurt is a fermented dairy product consumed worldwide. In the recent years, a novel product has been produced using probiotic bacteria known as probiotic yogurt which is beneficial and functional dairy product. Microencapsulation technique can lead to an increase in survival rate of the probiotic bacteria in dairy products during storage. In this research, the effect of sodium caseinate (0-3%) and microencapsulation of Lactobacillus acidophilus in the context of sodium caseinate- gellan gum were studied on the physicochemical properties (pH, apparent viscosity, water holding capacity (WHC) and synersis) and survival rate of the mentioned bacteria in the probiotic yoghurt during 21 days storage at 4˚C. The results of qualitative properties of produced yoghurt showed that by addition of sodium caseinate to milk, acidity, water holding capacity and apparent viscosity of yoghurt were increased during storage, but the amount of synersis was decreased. Results also showed that yoghurt samples containing encapsulated L. acidophilus had high apparent viscosity and WHC compared to the free form of the bacteria, while lead to less acidity and syneresis. According to the obtained results from microbial counts, microencapsulation of L. acidophilus and using sodium caseinate dramatically improved its survival during storage time, so that the highest number of bacteria survival at the end of day 21 belonged to the sample containing 3% sodium caseinate and encapsulated cells.