Effects of succinylation on the structure and thermal aggregation of soy protein isolate

The structures of soy protein isolate, beta-conglycinin, and glycinin at increasing succinylation levels (0-94.88%) were determined to control the formation of soy protein thermal aggregates. In addition, the thermal aggregation was investigated under various temperatures (70-100 °C) and ionic strengths (0-1.0 mol/L NaCl) at pH 7.0. Results showed that soy protein isolate, beta-conglycinin, and glycinin underwent obvious structural changes when their succinylation degrees reached around 60%, 30%, and 65%, respectively. After which, the acylation rates markedly declined. During succinylation, soy proteins, particularly glycinin, endured gradual damages in its secondary and tertiary structures. Consequently, the thermal stability of glycinin was reduced, whereas that of beta-conglycinin was hardly affected. However, as the colloid stability of succinylated soy protein isolate was enhanced significantly, its thermal aggregation was markedly suppressed. Thus, succinylation could be used to improve the stability of soy proteins after heating.