Solid State Bioconversion for Producing Functional Flours from Whole Quality Protein Maize and Common Beans with Enhanced Nutritional Value, Antioxidant and Antihypertensive Potential

Abstract

The aim was to develop functional flours with enhanced nutritional value, antioxidant and antihypertensive potential from quality protein maize and common beans throughout solid state bioconversion (SSB) process. The SSB processes were performed at 35°C/84h (maize) and 38°C/100h (beans) using a rhizopus oligosporus strain. The bioprocessed maize and bean (bioprocessed bean cotyledons blended with seed coats) samples were dried, cooled, and milled to obtain bioprocessed whole quality protein maize flour (BQPMF) and bioprocessed common bean flour (BCBF), respectively. SSB process increased the protein content (26.8 -33.5%), soluble, insoluble and total dietary fiber contents (132-196%, 15-24%, and 40-43%, respectively), resistant starch (130-133%), calculated protein efficiency ratio (C-PER; 33-49 %), phenolic content (69.5-127.02%), antioxidant capacity (AoxA) (38-75%) and angiotensin converting enzyme-inhibitory (ACE-I) activity of quality protein maize and common beans. The mixture prepared from 60% BQPMF+40% BCBF had, in dry basis, 19.78% proteins, 24.65% total dietary fiber, 3.92% resistant starch, and C-PER 2.24, antioxidant activity 199.24 μmol Trolox equivalents/g sample, and IC 50 (antihypertensive potential) 25.12 µg peptide/mL suspension. The SSB bioprocess resulted in an effective strategy to improve nutritional value, phenolic content, antioxidant activity, and antihypertensive potential of quality protein maize and common beans. The flours developed in this work (BQPMF, BCBF and its mixture) can be considered functional foods of high nutritional value and with potential for prevention and control of degenerative diseases such as hypertension and those derived from oxidative stress.