Bioconversion of Soybean Isoflavone by Lactobacillus plantarum and Bifidobacterium longum

Abstract

Abstract In this study, phytoestrogen for the industrial production of soybean probiotics by lactic acid bacteria (LAB) was studied in a soybean extract. Soybean was fermented with LAB, Lactobacillus plantarum KCTC 3108 and Bifidobacterum longum ATCC 15707. The change in the content of various isoflavones (aglycone and glucoside) and the β-glucosidase activity in soybean during fermentation were investigated and shown to be dependent on the starter organism. Soybean extract powder fermented with L. plantarum showed the highest β-glucosidase activity and the greatest increase in the aglycone content. After 48h of fermentation, the contents of daidzin, genistin and glycitin in L. plantarum decreased from a mean initial levels of 83.03±2.17, 168.13±8.17 and 20.02±1.07, respectively, to mean levels of 5.34±3.24, 3.79± 0.57 and 1.87±1.09 mg/100 g. Whereas, after 48h fermentation, the contents of daidzein, genistein and glycitein increased from a mean initial levels of 8.09±0.78, 11.20±0.84 and 4.71±0.46, respectively, to mean levels of 85.76±0.84, 175.87± 2.21 and 22.41±0.91 mg/100 g. Taken together, these results suggested an increase of aglycones and decrease of glu-coside in isoflavones occurred during fermentation, which coincided with an increase of β-glucosidase activity in the fermented soybean extract powder.