Moringa oleifera leaf protein fractions and its emulsifying properties at different pHs

• Moringa oleifera leaf protein extract had molecular weight ranging from 25-130 kDa. • Albumin was the predominant protein on Moringa oleifera leaf protein • Moringa oleifera leaf protein fraction had different electrophoretic profiles. • The pH affected emulsifying properties of Moringa oleifera leaf protein extract. • The interfacial composition of adsorbed protein was pH dependent. Moringa oleifera (MO) leaf powder (MOLP) is one of the vegetable protein sources and its uses in food formulations are affected by the protein properties. This study aimed to evaluate the characteristics of MOLP protein and its function to stabilize emulsion at different pH of 4, 5, 6, 7, 8, and 9. The results showed that the MOLP protein fractions consisted of albumin (11.67%), globulin (0.83%), prolamin (2.05%) and glutelin (5.1 %) with molecular weight (MW) ranging from 25 to 245 kDa. Increasing pH increased emulsifying activity index (EAI), emulsion stability index (ESI), and surface load of MOLP protein extract. Not all proteins were adsorbed at oil globule interface, the adsorbed proteins were dominated by low MW probably due to the dissociation of proteins caused by ionization at different pH. Changes in protein composition at the oil–water interface also influenced the emulsifying properties.