Optimization of Moringa oleifera leaves protein extraction conditions and characterization based on nutritional quality and functional properties for sustainable protein source

• Moringa oleifera leaves protein concentrate is suitable for food industry applications. • pH, temperature, Liquid to solid ratio and time impacted protein recovery. • Optimum extraction conditions were determined using response surface methodology. • The concentrate exhibited high protein digestibility and emulsion capacity. • The protein was in a compact structure with high β-sheets content and no α-helix. Plant leaves could be used in the food industry as an important protein source for their nutritional quality, bioactive and techno-functional properties. Moringa oleifera leaves are particularly attractive because of their high protein content with a well-balanced amino acid profile and including all essential amino acids. In this study, we optimized the preparation of protein concentrate from Moringa oleifera defatted leaf flour and evaluated its properties. Preliminary experiments were carried out to identify important parameters and conditions, and a Box-Behnken experimental design was used to investigate effect of extraction conditions on the protein extraction. Optimization was carried out by graphic superimposition of contour plots and optimum conditions were verified experimentally. The optimum conditions were pH 11.9, time 237 min, temperature 49.4 °C, and liquid to solid ratio 49.5/1 (v/w). Under these conditions, Moringa oleifera protein concentrate (MOLPC) showed 43.6 % protein content, and the concentrate exhibited high protein digestibility (70.3 %). In addition, the concentrate presented adequate functional properties, particularly emulsifying properties. The extracted protein was probably in an aggregated conformation since the β-sheets secondary structure was the major one, and surface hydrophobicity was high. At the end, we expect these findings could enhance utilization of Moringa oleifera protein concentrate in the food industry.