Preparation, characterization and functional properties of Moringa oleifera seed protein isolate

Moringa seed protein isolate (MPI) was prepared by aqueous salt extraction followed by watering-out to precipitate proteins. Extraction and precipitation steps were optimized to achieve maximum MPI yield. Besides, MPI was characterized based on its composition and functional properties. Among the multiple salts examined, Na2SO4 (69.9%), KCl (66.2%), NaCl (65.4%), and NaBr (63.5%) displayed better protein extractability as well as higher MPI yield (~ 52%) with a protein content of > 90% d.b. However, NaCl was preferred considering its wider acceptance. Based on response surface methodology analysis, solvent-to-flour ratio, 22:1 (v/w), NaCl concentration, 0.4 M and temperature, 55 °C were found optimal for maximum protein extractability of 70.3%. Subsequent watering-out resulted in a maximum MPI yield of 56% (protein basis). MPI contained all the protein subunits (6.5, 14, 29 kDa) present in its source. It also scored over commercial soy protein isolate in many of the functional properties.