Enhancement of the antioxidant capacity of soymilk by fermentation with Lactobacillus rhamnosus

Abstract

In order to enhance the bioactivity of soy beverages, fermentation of soymilk was assayedusing Lactobacillus rhamnosus CRL981 as a b-glucosidase producer. The biological activity ofthe fermented soy beverage enriched in isoflavone aglycones was determined by severalmethods to evaluate different antioxidant mechanisms. Fermented soymilk exhibitedhigher antioxidant activity (71.2 ± 4.0%) determined by b-carotene bleaching method butlower, although significant, DPPH radical scavenging effect (29.5 ± 0.9%) than the unfermentedsoymilk used as control. The fermented soymilk extracts were able to inhibit theoxidation of DNA induced by Fenton s reagent. The increase of isoflavone aglycone contentsduring fermentation was a result of b-glucosidase activity towards isoflavone glucosides.This process allowed obtaining a soy beverage with enhanced antioxidant capacityable to contribute to the health and nutritional status improvement of consumers.