Perspective and quality aspects of fermentation in rice milk: effects of bacterial strains and rice variety

Although fermented dairy products with health benefits are the most popular market, the demand for plant-based products is rapidly growing. The current study investigates the effect of involving Lactobacillus, Streptococcus, Bifidobacterium and Propionibacterium strains on rice milk fermentation. Rice's milks were characterised in terms of nutritional value. The acidification process, growth of beneficial bacteria, physicochemical alteration and sensory characteristics of fermented beverages produced from the milk of different types of boiled rice were investigated. The results revealed that changes in all these characteristics depend on the bacterial strain and the rice variety. The highest increase in antioxidant activity after fermentation was shown by Bifidobacterium longum B379M, Bifidobacterium bifidum and Propionibacterium freudenreichii subsp. shermanii KM-186 for Krasnodar, basmati and black rice, respectively. The use of chosen bacteria for red rice milk fermentation led to a decrease in antioxidant activity. The highest values for polyphenol content were for samples fermented by Bacillus coagulans MTCC5856 and Streptococcus thermophilus. The greatest increase in bacterial growth during fermentation was demonstrated by the sample fermented with Lactobacillus delbrueckii subsp. bulgaricus, B. bifidum and P. freudenreichii subsp. shermanii KM-186. The highest acidification rate values, the most favourable doubling time and the specific growth rate were for samples fermented with L. delbrueckii subsp. bulgaricus, S. thermophilus, Lactobacillus acidophilus H9, B. coagulans MTCC 5856, B. bifidum, P. freudenreichii subsp. shermanii KM-186 depending on the rice type. Considering all data obtained, including sensory characteristics, the most promising bacteria for fermentation are B. bifidum and B. longum B379M.