Effect of adding millet milk on viability of Lactobacillus acidophilus LA-5, starter bacteria and some physicochemical characteristics of the probiotic yogurt

Using food for transferring the probiotic bacteria has been considered by food scientists for decades. To promote health benefits of probiotic bacteria they must be kept alive before they reach the large intestine. Therefore, methods for preserving probiotics should be adopted. Among different methods, application of prebiotics substances is consideredin many formulations. Millet milk, in addition to being nutritious, can be used as a prebiotic source because of its soluble and insoluble fibers and resistant starch. Thus, the aim of this study is to investigate the application of millet milk in the production of functional yogurt. In this study, the replacement of 0, 10, 15 and 20% (v/v) millet milk with low-fat milk (2.5%) was performed and its effect on the viability of Lactobacillus acidophilus LA-5 and starter cultures bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus) as well as the physicochemical properties of yogurt was investigated during 21 days of storage. The results showed that the replacement of millet milk caused a decrease in pH and viscosity, as well as acidity, but the viability of Lactobacillus acidophilus LA-5 bacteria increased. Generally, in all samples, total count of probiotic bacteria and starter cultures and pH were reduced and acidity was increased upon storage. Among all treatments, yogurt containing 10% millet milk was selected as the best treatment because of its higher organoleptic acceptance.