Influence of commercial culture composition and cow milk to soy milk ratio on the biochemical, microbiological, and sensory characteristics of a probiotic fermented composite drink.

In this study, the effects of various ratios of cow milk to soy milk (100:0, 75:25, 50:50, 25:75, and 0:100) and three types of commercial culture composition (ABY-1, MY-720, and YO-Mix 210; all of them containing Lactobacillus acidophilus, Bifidobacterium lactis, and yogurt cultures) on the biochemical, microbiological, and sensory characteristics of a probiotic fermented composite drink during incubation and refrigerated storage were investigated. It was found that the shortest fermentation time, greatest mean pH drop rate, and mean acidity increase rate were related to the 50:50/ABY treatment. 25:75/ABY and 25:75/MY treatments exhibited the highest viability of B. bifidum and/or L. acidophilus at the end of 21 days of refrigerated storage. The influence of the type of starter culture composition on the sensory properties of the final products was not significant. Based on microbial and sensory evaluations, using the 50:50 ratio with each type of culture composition was considered as the most suitable treatment.