Physicochemical Properties and Bioactivities of Rice Beans Fermented by Bacillus amyloliquefaciens

The purpose of this study was to investigate the physicochemical properties and bioactivities of rice beans (Vigna umbellata) fermented by Bacillus amyloliquefaciens. The fermentation conditions were optimized on the basis of the fibrinolytic activity. Under the optimal fermentation conditions, the fibrinolytic activity reached a maximum of 78.0 FU·g−1 (4890 IU·g−1, fibrin plate method, FU: fibrin degradation unit). The contents of peptides (which increased from 2.1 to 10.9 g per 100 g), total phenolics (from 116.7 to 388.5 mg gallic acid per 100 g), total flavonoids (from 235.5 to 354.3 mg rutin per 100 g), and anthocyanin (from 20.1 to 47.1 mg per 100 g), as well as the superoxide dismutase activity (from 55.3 to 263.6 U·g−1) in rice beans were significantly increased after fermentation. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) free radical scavenging activities and ferric reducing antioxidant power (FRAP) of fermented rice beans were 1.9–4.8 times higher than those of unfermented rice beans. Moreover, fermentation induced an increase in the dipeptidyl peptidase IV (DPP-IV) inhibition, α-glucosidase inhibition, and anticoagulant activities of rice beans. Rice beans fermented by Bacillus amyloliquefaciens may serve as a functional food with potential benefits for the prevention of thrombotic diseases.