Optimization of Fermentation Process for Improving Soy Isoflavones Aglycone Content in Bean Dregs by Lactobacillus plantarum PL70a

Abstract

Aglycone-type soy isoflavones have higher biological activity than glycoside-type soy isoflavones. Bean dregs are rich in glycoside-type soy isoflavones. In order to improve the biological activity of soy isoflavones in bean dregs, the Lactobacillus plantarum PL70a was screened and the fermentation process of converting glycoside-type soy isoflavones into aglycone-type in bean dregs was optimized by single-factor experiments and the response surface methodology. The optimal fermentation process was as follows: (NH4)2SO4 was added in an amount of 0.17%, glucoamylase was added in an amount of 0.87%, inoculation amount was 17%, sucrose was added in an amount of 1.3%, and fermentation time was 3 days. Under this process, the content of aglycone-type soy isoflavones in bean dregs significantly increased. Trypsin inhibitors and antigen proteins were almost removed. The fermentation process provides a good reference for the low-cost processing of high-quality soy isoflavone aglycone food.