Improving the biological activity and emulsification ability of soybean meal hydrolysate via non-covalent interactions with polyphenols

The present study investigates the effects of non-covalent interactions between soybean meal hydrolysate (SMH) and four different polyphenols on their structure, biological activity, interaction force pattern, and emulsification ability. The formation of SMH-polyphenol complexes was confirmed by SDS-PAGE, the interaction force pattern, and the polyphenol content. The formation of the complexes was accompanied by an increase in the content of α-helices and random coils; the UV absorption and number of free sulfhydryl groups increased, indicating the unfolding of SMH, which demonstrated a disordered structure. The interaction also reduced the fluorescence intensity of the SMH, indicating their binding to the polyphenols, resulting in fluorescence quenching. These modifications changed the secondary structure and hydrophobic nature of amino acids, affecting the antioxidant activity and emulsification activity of the SMH. Among the complexes, SMH-procyanidin had the highest antioxidant capacity (97.96% and 65.55%, corresponding to the ABTS and DPPH radical-scavenging capacity, respectively), total polyphenol content (193.34 g/kg), emulsification activity (75.15 m2/g), and emulsification stability (949.58 min). Our findings demonstrate that polyphenols form non-covalent interactions with SMH, enhancing their antioxidant and emulsification abilities. Thus, polyphenols can be used to prepare soybean foods with high antioxidant activity and enhanced emulsifying properties.