Enhancement of nutritional properties, and antioxidant and antihypertensive potential of black common bean seeds by optimizing the solid state bioconversion process.

The aim of this work was to obtain a functional flour with enhanced nutritional properties, and antioxidant and antihypertensive potential from black bean seeds by optimizing the solid state bioconversion (SSB) process using a Rhizopus oligoporus strain. Response surface methodology was applied as optimization technique. A central composite experimental design with two factors [fermentation temperature (FT) = 30-40 °C/fermentation time (Ft) = 6-108 h] and five levels was used (13 treatments). The bioprocessed cotyledons from each treatment were dried, milled, and blended with its previously dried-milled seed coats. The best combination FT/Ft of SSB to obtain the functional flour was 38 °C/100 h. SSB increased the calculated protein efficiency ratio (from 1.59 to 2.40), antioxidant activity (from 13 948 to 22 733 µmol ET/100 g, dw), total phenolic compounds (TPC) (from 190 to 432 mg EGA/100 g, dw) and antihypertensive potential (IC(50) from 95.57 to 0.0321 µg/mL). SSB is an effective strategy to improve the TPC of common beans for enhanced functionality.