Interfacial Rheological Behavior and Whipping Properties of Soy Protein and Its Hydrolysates

This article investigated soy protein isolate (SPI),β-conglycinin (7S),soy protein selective hydrolysate (SPSH) and soy protein limited hydrolysate (SPLH) by polyacrylamide gel electrophoresis (SDS-PAGE),interfacial shear rheology and whipping experiment to measure the adsorption behavior of different structural soy proteins at the air-water interface and to explore their relationships with whipping properties. SDS-PAGE indicated that SPI was consisting of 7S and 11S. After the selective hydrolysis,the 11S subunit band of SPSH disappeared and the 7S subunit of SPSH remained. The hydrolysis degree of SPLH was 1% with the molecular weight was about 10 kDa. The interfacial shear rheological behavior showed that the adsorption speed of SPI and 7S were slow and SPLH could be adsorbed quickly to the interface. 7S and peptides existed in SPSH,which made SPSH not only could be adsorbed to the interface quickly but also could form a viscoelastic interfacial film simultaneously. The whipping experiment results showed that the foam expansion of SPSH and SPLH increased significantly from 450% to 680% and to 700%,respectively. Hydrolysis could reduce the molecular weight of soy protein and accelerate the adsorption of protein at the interface,which resulted in the increase of foam expansion. This research provides practical significance for the application of soy protein in aerated foods.