Effects of different charged polysaccharides on the gelation properties and in vitro digestibility of potato protein gel: Insight into underlying mechanisms

This study investigated the effects of different charged polysaccharides, including cationic chitosan (CS), neutral konjac glucomannan (KGM) and guar gum (GG), and anionic kappa-carrageenan (CA) and sodium alginate (SA), on the gelation properties and in vitro digestibility of potato protein isolate (PPI) gel. The results showed that anionic polysaccharides (CA and SA) were most effective in increasing the WHC (approximately 30%) and texture properties of composite gels, followed by neutral polysaccharides (KGM and GG) and then cationic CS. The anionic polysaccharides (CA and SA) showed the greatest effect on increasing the absolute zeta potential, inducing the exposure of hydrophobic groups, enhancing the hydrophobic interactions, and promoting the generation of beta-sheet structures, thus contributing to the formation of fine and well-organized gel network. By contrast, the electrostatic neutralization between cationic CS and negatively charged PPI molecules under the neutral environment accelerated the protein self-aggregation, thus structuring dense protein domains and nonhomogeneous network structures. It also resulted in the greatest reduction in the protein digestibility (from 82.23% to 77.33%). The neutral KGM/GG caused no significant changes in zeta potential but led to the most prominent enhancement in the hydrogen bonding, which contributed to the generation of uniform and continuous microstructures with regular large pores. This study provided a new perspective to understanding the regulation and improvement of the quality of plant protein-based gel foods by controlling the ionic types of added polysaccharides.