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Abstract
Effects of enzymolysis by seven proteases (Alcalase, Bromelain, Flavourzyme, Papain, Pepsin, Protamex, and Trypsin) with distinct cleavage specificities on the emulsification performance of hempseed protein (HPI) and its correlation with the structural and interfacial characteristics were explored in this study. Upon enzymolysis, a remarkable decrease in α-helix and β-turn was observed in resultant hydrolysates (HPH), accompanied by a rise in β-sheet and random coil, notably by Alcalase, Bromelain, Papain, and Trypsin. Overall, proteolysis led to noticeable reductions in surface hydrophobicity and total sulfhydryls as well as a redshift in intrinsic fluorescence, with Papain showing the most pronounced effects, possibly due to its higher hydrolysis degree (4.00 %). Interestingly, among the seven HPHs, Papain-HPH with the highest solubility (67.4 %) and smallest molecular weight exhibited compromised interfacial activity, lowest emulsifying activity (EAI, 1.67 m2/g), and highest creaming index (CI, 64 %). Contrastively, Trypsin hydrolysis significantly improved the interfacial activity, albeit causing a notable decrease in interfacial viscoelasticity of the absorbed layers. Consequently, Trypsin yielded the best EAI (10.5 m2/g) and emulsion stability (CI, 4 %); yet, the smallest emulsion droplets with homogeneous distribution and high apparent viscosity were spotted. Additionally, the oxidative stability of emulsions was conspicuously enhanced, contingent upon the antioxidative capacity of HPHs.