Production of fermented red beans with multiple bioactivities using co-cultures of Bacillus subtilis and Lactobacillus delbrueckii subsp. bulgaricus

Red beans exhibit many biofunctions, including the stimulation of intestinal motility, improvement of anemia and elimination of edema. This study was conducted to evaluate the functional properties of microbially fermented red beans produced under different fermentation conditions and to establish the optimum fermentation conditions for the production of fermented red beans with multiple biofunctions. The optimum fermentation conditions were the fermentation of red beans by a co-culture of Bacillus subtilis and Lactobacillus bulgaricus in the presence of 1% glucose, incubated at 30 °C for 120 h and stirred every 24 h. Compared with unfermented red beans, red beans fermented under the optimum conditions contained a higher concentration of antioxidant substances, including total phenolics, anthocyanin, flavonoids and vitamins C and E. The results of tests for DPPH-radical scavenging, ferrous ion chelation and reducing power implied a high antioxidant content. Fermented red beans exhibited nattokinase activity and contained a significant amount of potential probiotics.