Heat drying RGI rich pectin with significant aggregation and poor solubility could be improved by inserting specific polysaccharides as steric scaffolds.

RGI (rhamnogalacturonan-I) pectin, a polyhydroxy-carboxylic acid polymer abundant in neutral sugar side chains, exhibits thermal aggregation during heat drying which leads to its poor solubility. It is hypothesized that insufficient electronic repulsion among the neutral sugar side chains causes their entanglements. Therefore, our purpose is to offer other polysaccharides to the system as steric scaffolds to inhibit aggregation potentially. Various functional polysaccharides with distinct charge characteristics, including chitosan, glucan, commercial pectin, κ-Carrageenan, and ι-Carrageenan, were blended with RGI rich pectin solution before ethanol precipitation. The effect and the interaction mechanisms of these complexes were analyzed through solubility, Zeta potential, particle size, bulk density, rheology, and FESEM characterization. The results revealed that the type and density of charges significantly influenced aggregation behavior: cationic polysaccharides tended to aggravate aggregation while anionic polysaccharides exhibited substantial improvement in reducing aggregation, particularly at higher charge densities. Interestingly, the glucan with charge neutrality also demonstrated positive effects, suggesting the scaffolds could also act through the steric hindrance. These findings elucidate the interaction mechanisms between RGI rich pectin and various polysaccharides, and incorporating the insoluble heat-dried RGI rich pectin as part of a soluble mixed colloid for joint applications to enhances its value.