Functional Properties of Cowpea (Vigna unguiculata) Flour As Affected by Soaking, Boiling, and Fungal Fermentation

Abstract

Functional properties of cowpea flour as affected by soaking, soaking/boiling (S/B), and fermentation of seeds with Rhizopus microsporus subsp. oligosporus before milling were investigated. Soaking and fungal fermentation had less influence on functionality of flour compared to S/B, which markedly decreased solubility and impaired emulsifying properties. Solubility of heat-denatured proteins was slightly improved by fermentation. High emulsion capacity was not associated with high emulsion viscosity or solubility. The combined effects of heat treatment and fungal fermentation on equilibrium moisture content were apparent at 75−97% equilibrium relative humidity. Cowpea flours were consistently more hydrophilic than lipophilic, regardless of processing treatment. The least gelation capacity of flours increased as a result of heat treatment. Keywords: Cowpea flour; Vigna unguiculata; functional properties; soaking; heat treatment; fungal fermentation; Rhizopus microsporus subsp. Oligosporus