Effect of solid-state fermentation using strains of Rhizopus oligosporus C1 on chemical characteristics and antioxidant activity of peas.

Tempeh is a traditional Indonesian food, made from solid state fermentation of soybeans using Rhizopus spp. Tempeh can be developed from nutrition-rich substrates other than soybeans. This study aims to evaluate the potency of peas as the alternative substrate for tempeh. Peas were fermented using Rhizopus oligosporus C1 with the variation of culture concentrations (10% and 20%) and fermentation times (0, 24 and 48 hours) to produce tempeh. Distilled water was used to extract peas tempeh. The chemical characteristics of peas tempeh water extract, i.e., proteins, polyphenols, flavonoid content, and antioxidant bioactivity, were evaluated in this study. The profile of chemical compounds in tempeh with the highest antioxidant activity was identified using LC-MS/MS. The concentration of culture and duration of fermentation affected the characteristics of peas tempeh. The utilization of 20% R. oligosporus C1 and 24 hours of fermentation gave the highest antioxidant activity, proteins, polyphenols, and flavonoid content. LC-MS-MS analysis shows two compounds (Kadsurenin E dan Nigakilactone M) in a sample with the most increased antioxidant activity. Fermentation using R. oligosporus C1 can be used as an alternative technology to enhance peas' nutrition contents and bioactivity. [ABSTRACT FROM AUTHOR]