Functional Properties of Moringa Oleifera Protein Isolates as Influenced by Different Isolation Techniques, pH, and Ionic Strength

Plant-based proteins are increasingly being utilized as they are sustainable, economical, and can enhance the organoleptic properties of food products. This study investigated the effect of extraction and isolation techniques (alkaline extraction & isoelectric precipitation and salt extraction & micellization) on the functional properties ((solubility, water holding and oil absorption capacity (WHC/OAC), emulsifying activity and stability index (EAI/ESI), foaming capacity and stability (FC/FS), and gelation)) of Moringa oleifera protein isolates. The effect of ionic strength (0.2–1.0 M NaCl) and pH (2–10) on the functional properties were also investigated. Salt extraction & micellization produced an isolate with a high solubility at 0.8 M NaCl and pH 10 (98.1%, 91.8%), EAI at 0.6 M NaCl and pH 6 (56.2 m²/g, 77.0 m²/g), and ESI at 0.8 M NaCl and pH 4 (64.4 min, 243.5 min). Alkaline extraction & isoelectric precipitation resulted in an isolate with a high WHC at 0.6 M NaCl and pH 10 (5.8 g/g, 4.0 g/g), OAC (4.9 g/g), FC at 0.4 M NaCl and pH 2 (203.3%, 163.3%), and gelation at 0.2 M NaCl, 0.4 M NaCl, and pH 8 (20.0%). Both extraction methods can be applied in the valorization of M. oleifera seedcake. Micellized isolate could be used in food emulsions due to better emulsifying properties, while isoelectric isolate can be applied in meats and sauces, owing to better water holding and oil absorption capacity. M. oleifera protein isolates are promising plant-based proteins that can be used in food formulations or to replace animal-derived proteins in food.