Effects of limited enzymatic hydrolysis, pH, ionic strength and temperature on physicochemical and functional properties of palm (Elaeis guineensis Jacq.) kernel expeller protein

Limited hydrolysates ranging from 6.82 to 16.74 % degree of hydrolysis (DH) were produced from palm kernel expeller protein (PKP) using Alcalase. The nutritional value, physicochemical and functional properties of PKP and the hydrolysates, especially effects of DH, pH, ionic strength and temperature on these properties were studied. Results showed that all the hydrolysates showed higher nutritive value, better thermal stability and solubility (70.68–99.13 g/100 g) than PKP. The surface hydrophobicity, emulsifying properties and foaming activity were improved by limited enzymatic hydrolysis (DH: 6.82 to 11.72 %), whereas the foam stability, viscosity, water and oil holding capacity were negatively correlated with DH. Increase in ionic strength (from 0 to 0.4 mol/L) or temperature (from 30 to 50 °C) enhanced the solubility, emulsifying properties and foaming activity. But high temperature remarkably weakened the foaming properties and viscosity. Solubility, surface hydrophobicity and molecular weight influenced the emulsifying and foaming properties. PKP and the hydrolysates were good protein source.