Changes in phytoestrogen contents and antioxidant activities during fermentation of soybean-powder milks prepared from different soybean cultivars by Lactobacillus plantarum P1201

This study evaluated the changes of phytoestrogen contents and antioxidant activities of soybean-powder milk (SPM) prepared from yellow soybean during fermentation with Lactobacillus plantarum P1201. In consequence, the levels of total phenolic and isoflavone-aglycone contents, ABTS and DPPH radical-scavenging activities, and FRAP assay values increased, while isoflavone-glycoside contents decreased during fermentation. The highest levels of daidzein, glycitein, and genistein were present in the Daepung SPM at concentrations of 177.92, 20.64, and 106.14 μg/g, respectively after 60 h of fermentation. Moreover, Daepung SPM showed the highest DPPH radical-scavenging activity of 48.54%, an ABTS radical-scavenging activity of 99.25%, and a FRAP assay value of 0.84 at the end of fermentation. The fermented Daepung SPM possessed highest isoflavone aglycone contents and antioxidant activities, which can be utilized for the development of functional foods.