Effect of high-pressure processing enzymatic hydrolysates of soy protein isolate on the emulsifying and oxidative stability of myofibrillar protein-prepared oil-in-water emulsions

BACKGROUND Oil-in-water (O/W) emulsions are thermodynamically unstable and are easily oxidized. Recently, protein hydrolysates have been used to enhance the emulsifying and oxidative stability of emulsions. High-pressure processing (HPP) enzymatic hydrolysates of soy protein isolate have higher bioactivities. The objective of the study was to investigate the effects of various soy protein isolate hydrolysate (SPIH) concentrations obtained during different 4 h pressure treatments on improving the emulsifying and oxidative stability of myofibrillar protein (MP) emulsions. RESULTS Emulsions with 4 mg mL(-1) SPIH obtained at 200 MPa had the highest emulsifying activity index and emulsion stability index (P <= 0.05). This increase in emulsion stability was related to increased zeta potential and reduced average particle size. Optical microscopy and confocal laser scanning microscopy observations confirmed that emulsions with 4 mg mL(-1) SPIH possessed relatively small oil droplets. The addition of SPIH obtained at 200 MPa significantly reduced thiobarbituric acid reactive substance values (P <= 0.05) of emulsions during 8 days of storage. Concurrently, the carbonyl content remained the lowest and the sulfhydryl content remained the highest, which indicated that the emulsions had higher protein oxidative stability. CONCLUSIONS SPIH obtained under HPP could improve the emulsifying and oxidative stability of MP-prepared O/W emulsions.