Effect of microencapsulation of probiotic bacteria with calcium alginate on cell stability during the refrigerated storage period in the Iranian yogurt drink (Doogh)

Microencapsulation of probiotic bacteria by using hydrocolloid materials provides one of the best possible cares to protect them against detrimental conditions of fermented milks and to extend the shelf life of probiotic fermented products. The most widely used encapsulating material is Ca-alginate. In this research, the effect of microencapsulation of AB-type culture (L. acidophilus LA-5 and Bifidobacterium lactis BB-12) with calcium alginate on cell survival over a 42-day refrigerated storage period (at 4 degrees C) in Iranian yogurt drink (Doogh) was studied. The initial pH of product at the start of storage time was 4.522 and the final pHs at the end of storage period were 4.510 and 3.775 for the samples containing encapsulated and unencapsulated cells, respectively; indicating considerably higher metabolic activity of free cells compared with entrapped ones. At d 42, viable counts of L. acidophilus and bifidobacteria in the samples containing encapsulated cells were about 5.5 and 4.0 log cycles higher than those containing free cells, respectively.