Effect of protein and oil volume concentrations on emulsifying properties of acorn protein isolate

This study aims to extract acorn protein isolate (API) from locally abundant waste acorn fruit and investigate its emulsification behavior by mixing different protein (0.1-2% w/v) and oil volume concentrations (5-45% v/v). Significant decrease in emulsifying activity index (EAI) and an increase in emulsifying stability index (ESI) were observed with an increase in API concentrations (P < 0.05). Droplet sizes of emulsions and viscosity were observed to decrease significantly (P < 0.05) with increase in API concentration while the increase was observed in interfacial protein concentration (Gamma). In contrast, increase in oil volume concentration results in increase of droplet sizes, packing fractions and viscosity, while decrease in Gamma values was observed. The results reveal that main fractions of API (66.2-14.4 kDa) were migrated to oil-water interface for emulsion stabilization. These results demonstrate the potential application of API in food formulation and development.