Modulating the gelatinization and retrogradation characteristics of corn starch by controlling pine kernel protein/egg white protein thermal co-aggregation

Abstract

Blending plant and animal proteins to tailor starch performance is challenging due to contradictions in their conformational relationships. Herein, egg white protein (EWP) and pine kernel protein (PKP) were combined to prepare corn starch-based ternary matrices of EWP/PKP blends and co-precipitates, and their effects on starch sol-gel transformation and retrogradation properties were traced. Co-precipitation treatment improved the cohesion and techno-functionality of dual-proteins by enhancing hydrophobic interactions, disulfide bonds, and hydrogen bonding rearrangements. At a PKP:EWP ratio of 1:7, co-precipitates increased the gelatinization onset temperature by 7.30 % and the loss tangent values by 285.71 %, while the gel hardness and fracture stress reduced by 114.32 g and 9.17 kPa, respectively. Driven by electrostatic repulsion along with enhanced hydrogen bonding and hydrophobic interactions, co-precipitates formed a homogeneous gel matrix with starch. Results from chromameter and LF-NMR indicated that gel brightness and water distribution were positively influenced by the co-precipitates. For retrogradation, numerous intermolecular disulfide bonds, β-turns, and random coil structures formed, driving the self-aggregation of PKP, EWP, and their blends. Co-precipitates caused a bridged ‘closed’ network that reduced R_1047/1022 and relative crystallinity by 48.21 % and 41.36 %, respectively. These findings offer scientific guidance for manipulating dual-protein co-aggregation for on-demand functionalization of starch hydrogels.