Characteristics and antioxidant activity of kidney bean (Phaseolus vulgaris L.) tempeh as functional food

Kidney bean (Phaseolus vulgaris L.) are seeds have antioxidant activity and their activity can be increased by fermentation. The study were aim to produce kidney bean tempeh varians of yeast concentration, namely 0.2; 0.4; 0.8; and 1.0% (w/w), and fermented for 24 hours at room temperature. The sensory characteristics like texture, mycelium growth on the surface and aroma of kidney bean tempeh were tested by 36 panelists. The kidney bean tempeh was extracted with methanol solution and antioxidant properties was determined by 2,2-dyphenyl-1-picrylhydrazyl scavenging method, the presence of phenolics and flavonoids was also determined. The characteristics of kidney beans tempeh was dense texture, white mycelium that covered the surface of the beans and distinctive aroma. The character of tempeh was obtained in tempeh produced using by 0.8% (w/w) yeast. The ability of kidney bean to inhibit DPPH was 434.51 ppm, while kidney bean tempeh extract was 1534.25 ppm. Total phenolics and flavonoids in kidney bean were 2.24 mg GAE/g and 0.075 mg QE/g, while total phenolics and flavonoids in kidney beans tempeh were 6.65 mg GAE/g and 0.26 mg QE/g respectively. The study results indicate that kidney beans tempeh has much higher antioxidant activity than kidney bean.