Influence of heat treatment on structure, interfacial rheology and emulsifying properties of peanut protein isolate

Abstract

The influence of heat treatment on the protein size, zeta potential, surface hydrophobicity, secondary structure, interfacial rheology and creaming stability of peanut protein isolate (PPI) was studied. Heat treatment of PPI increased the protein size, surface hydrophobicity and interface diffusion rate, and decreased the protein zeta potential, particularly heat treatment at 80°C for 30 min (PPI-80), which increased the surface hydrophobicity from 117.33 ± 2.77 to 253.24 ± 2.47. Interfacial rheology results demonstrated that the heat treatment promoted the absorption of PPI at the oil-water interface, which might be due to the increase of surface hydrophobicity. In contrast, the heat treatment at 90°C resulted in slightly lower surface hydrophobicity and K_diff compared with PPI-80 due to the hydrolysis of partial protein aggregates during high temperature. Moreover, heat-treated PPI showed better emulsifying properties than unheated PPI. These results would be useful to expand the utilization of PPI products in the food processing industry.