Heat-induced mung protein isolate hydrogels enhanced via chitosan: Mechanisms and applications in β-carotene encapsulation
Shanshan Wu, Hui‐Wen Gu, Yidan Xu, Yue Wang, Youfa Wang, Vijaya Raghavan, Jin Wang
Abstract
Mung protein isolate (MPI) is a kind of highly nutritious, accessible, and hypoallergenic plant-based protein. However, its poor gelling ability limits its exploitation and application. This work investigated the influences of chitosan (CS) on the gelling capacities of MPI and elucidated the underlying mechanisms. CS interacted with MPI primarily through hydrogen bonds and salt bridges, which promoted the unfolding of the tertiary structure of MPI and the conversion of α-helices into β-sheets. CS was also found to restrict water mobility and alter the internal forces maintaining the structural integrity of hydrogels, characterized by reduced electrostatic interactions but improved hydrophobic interactions and hydrogen bonds. At higher concentrations (0.3 wt% and 0.5 wt%), self-aggregated CS acted as an active dehydrating agent to concentrate MPI, thereby promoting their gelation. Therefore, CS incorporation remarkably improved the textural and rheological properties of heat-induced MPI hydrogels in a concentration-dependent manner. The functional ingredient β-carotene (BE) interacted with the protein matrix primarily through hydrophobic interactions, and it exhibited synergistic effects with CS in reinforcing the gel networks. The composite hydrogels notably improved the stability of BE under ultraviolet irradiation and high temperatures and enabled its controlled release during simulated gastrointestinal digestion. The findings of this work provide a theoretical foundation for designing novel plant protein-based composite hydrogels with functional attributes suitable for precise nutrition and future foods. • Chitosan (CS) strengthened heat-induced mung protein isolate (MPI) hydrogels. • CS interacted with MPI primarily through hydrogen bonds and salt bridges. • CS restricted water mobility and concentrated MPI matrices to form a stronger network structure. • β-carotene (BE) presented good compatibility with MPI hydrogels through hydrophobic interactions. • The composite hydrogels exhibited excellent stabilization and controlled release of BE.