Characterization of Bifidobacterium strains for use in soymilk fermentation.

Soybean milk, which serves as a base for a variety of beverages, contains raffinose, stachyose, pentanal and n-hexanal; the former two may be responsible for flatulence after fermentation, whilst the latter two for a beany flavour. Twenty-seven strains of Bifidobacterium were analyzed for their alpha-galactosidase activity and the production of lactic and acetic acids to determine their potential for use in the production of fermented soymilk. The behaviour of three strains in soymilk was studied to determine their ability to reduce alpha-D-galactosyl oligosaccharides and produce lactic and acetic acids. They all were able to reduce stachyose and raffinose. Pentanal and n-hexanal were metabolized by Bifidobacterium breve MB233. These data indicate that bifidobacteria can be used for biotechnological processes that employ soymilk as the substrate. A product with low levels of alpha-D-galactosyl oligosaccharides and alkylic aldehydes may be obtained.