Impact of fructose and fructooligosaccharides supplementation upon the fermentation of hydrolyzed okara and its impact upon bioactive components

Abstract

Okara provide compounds of biological interest such as isoflavones and an increase of aglycone content can be obtained through fermentation with food - grade bacteria. This study aimed to evaluate the effect of fructose and fructooligosaccharides (FOS) on the growth of probiotic bacteria in hydrolyzed (by Cynara cardunculus enzymes) okara beverage, as well as on the antioxidant activity, isoflavones and total phenolic content of fermented okara beverage. Okara beverages were fermented using Bifidobacterium animalis ssp. lactis Bb - 12 and Lactobacillus rhamnosus R11 alone or as mixture of both, at 37 ºC, until it reached a pH value of 4.5. The growth of lac-tobacilli and bifidobacteria was evaluated throughout the fermentation, with increases of viable cells ranging from 1.5 to 3 log CFU/mL. Moreover, okara samples supplemented with a carbon source presented a higher growth rate than their non - supplemented counterpart, as expected. In addition, significant differences in aglycone content and antioxidant activity were observed for the okara samples fermented by different species, with the overall content of isoflavone aglycones increasing, the genistein presented the highest increase (ca. 16 - fold) in the fermented