Enhanced biological effect of fermented soy-powder milk with lactobacillus brevis increasing in γ-aminobutyric acid and isoflavone aglycone contents

Abstract

The research was aimed to analyze the functional constituents (GABA and isoflavone), radical (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and hydroxyl) scavenging activities and enzyme (α-glucosidase and lipase) inhibitory effects of soy-powder milk (SPM) and fermented soy-powder milk (FSPM) with varied Lactobacillus brevis. Ten γ-aminobutyric acid (GABA) producing lactic acid bacteria that showed 96-99% similarity with L. brevis, according to 16S rRNA gene sequence analysis, were isolated from fermented kimchi. The conversion rates of GABA were obtained 66.96-93.51, 63.76-84.58, and 57.05-69.75% in monosodium glutamate, gluten and soy protein, respectively. The levels of pH and glutamic acid of FSPM were found lower than those of SPM, but the acidity and GABA contents were higher. The GABA conversion rate of FSPM with BMK484 strain was attained the highest 69.97%. The contents of isoflavone glycoside (1290.93 μg/g) was higher in SPM, but the content of isoflavone aglycone (287.27-501.9 μg/g) was higher in FSPM. The levels of isoflavone aglycone such as daidzein, glycitein and genistein, were found as the highest 240.2, 61.24 and 200.45 μg/g, respectively, when FSPM was made with BMK484 strain. The DPPH, ABTS and hydroxyl radical scavenging and α-glucosidase and pancreatic lipase inhibitory activities of FSPM made with BMK484 strain were the relatively higher 60.31, 88.10, 61.25, 52.71, and 39.37%, respectively. Therefore, the L. brevis can be used as a material capable of simultaneously enhanced GABA and isoflavone aglycone in FSPM. ? The Korean Society for Applied Biological Chemistry 2018.