Dual modification of the aggregation behavior and in vitro digestion of oxidized pine kernel protein via a combination of homogenization and succinylation

Abstract

Protein oxidation affects the high-value utilization of nuts as oxidative attack causes protein aggregation, thereby challenging their technological functionality. Herein, a strategy using homogenization-assisted octenyl succinic anhydride (OSA) modification was proposed to tailor the structure, aggregation behavior, and digestive characteristics of oxidized pine kernel proteins. Results indicated that the ratio of α-helices to β-turns ranged from as low as 0.43 up to 0.67 after homogenization, suggesting greater molecular flexibility. With increasing protein oxidation, the acylation degree exhibited an inverted V-shaped trend, peaking at 67.22 %. OSA treatment reduced the aggregation rate and prolonged the lag time of proteins by stabilizing the α-helices and β-turns, increasing hydrogen bonding, and decreasing hydrophobicity. This increased the solubility of oxidized pine kernel proteins by ~30 % and improved their fluidity and thermal stability. A lower degree of succinylation was associated with higher free sulfhydryl content and surface hydrophobicity, which facilitated the thermal aggregation and the formation of elastomeric gels. Furthermore, the in vitro dynamic digestion and morphological observations of hydrolysis products indicated that cotreated proteins exhibited higher digestibility and formed small spherical particles ranging from 405.50 to 676.50 nm. These findings provide a promising approach to mitigate the adverse effects of oxidation on nut proteins.