β-Glucosidase activity and bioconversion of isoflavones during fermentation of soymilk

BACKGROUNDLactobacillus rhamnosusC6 strain showed higher -glucosidase activity as well as biotransformation of isoflavones from glycones (daidzin and genistin) to aglycones (daidzein and genistein) in soymilk. However, L. rhamnosusC2 and Lactobacillus caseiNCDC297 also exhibited similar activity during soymilk fermentation. These three strains can be selected for the development of functional fermented soy foods enriched with aglycone forms of isoflavones, such as soy yoghurt, soy cheese, soy beverages and soy dahi. RESULTSThe study determined -glucosidase activity of probiotic Lactobacillus cultures for bioconversion of isoflavones to aglycones in fermenting soymilk medium. Soymilk was fermented with six strains (L. rhamnosusC6 and C2, L. rhamnosusNCDC19 and NCDC24 and L. caseiNCDC17 and NCDC297) at 37 degrees C for 12 h. The highest -glucosidase activity and isoflavone bioconversion after 12 h occurred by L. rhamnosusC6 culture during fermentation in soymilk. Increased isoflavone aglycone content in fermented soymilk is likely to improve the biological functionality of soymilk (e.g. antioxidant activity, alleviation of hormonal disorders in postmenopausal women, etc.). CONCLUSIONLactobacillus rhamnosusC6 culture can be used for the development of functional fermented soy-based products. (c) 2014 Society of Chemical Industry