Physicochemical properties, protein digestibility and thermal stability of processed African mesquite bean (Prosopis africana) flours and protein isolates

The physicochemical, in vitro protein digestibility and thermal properties of dehulled (DPAF) and dehulled-defatted (DDPAF) African mesquite bean (Prosopis africana) flours and protein isolates produced by micellization and isoelectric precipitation were evaluated. Isoelectric precipitation method gave higher yield of protein isolate (30.46%) with higher protein content (81.34%) compared to the micellization which yielded 7.95% and 72.04%, respectively. Significant (p < 0.05) differences occurred among the total colour difference (23.63-53.12), whiteness (40.17-67.78), yellowness (36.81-49.26), browning (- 123.22 to 471.59) and flour colour (26.63-55.04) indexes and functional properties except dispersibility of the samples, indicating the effects of defatting and protein extraction methods. Micellized protein isolate recorded the highest oil (322%), water (300%) absorption and emulsion (64.67%) capacities, while the isoelectric precipitated protein had the highest protein solubility (81.75%). The protein isolates exhibited lower foam stability than the flours with micellized protein being the least. Thermal properties of the flours and protein isolates also varied with defatting and extraction methods. The dehulled P. africana flour and isoelectric precipitated protein showed single endothermic peaks with higher thermal stability compared to the dehulled-defatted flour and micellized protein which had two endothermic peaks. Flours and protein isolates showed in vitro protein digestibility between 76.44 and 80.00%, with micellized protein exhibiting the highest digestibility. Knowledge of the physicochemical properties of P. africana seed products would enhance their utilization in various food formulations, thereby contributing to food security in Africa.