Comparison of thickening properties of polysaccharides from four gelatinous edible fungi.

Polysaccharides from edible gelatinous fungi are promising natural thickeners for food applications, yet their thickening performance raries greatly among species. This study systematically compared the physicochemical and rheological properties of four polysaccharides extracted from Naematelia aurantialba, Auricularia auricula, Auricularia cornea var. Li., and Auricularia polytricha, and named NAP, AAP, ACP, and APP respectively. The physicochemical exhibited molecular weights (Mw) ranging from 2.80 × 106 to 3.11 × 106 Da. NAP and AAP were mainly composed of mannose, whereas ACP and APP were rich in glucose. All polysaccharide solutions (1.0%-2.5%) displayed typical shear-thinning behavior, and their apparent viscosities were influenced by both pH and Na+ concentration, following the order APP > ACP > AAP > NAP at equal concentrations. SEM observations revealed distinct microstructural morphologies: ACP and APP formed dense, honeycomb-like networks with uniform pore, while AAP displayed lamellar-porous and NAP exhibited loosely stacked lamellar structures. The higher Mw and lower polydispersity index of ACP and APP contributed to longer molecular chains and enhanced intermolecular entanglement, resulting in higher viscosity and more compact network formation. The relatively low viscosity of AAP can be mainly ascribed to its high content of low-molecular-weight fractions, while the lowest viscosity of NAP was closely correlated with its lowest Mw. Rheological analysis indicated weak gel-like behavior (G' > G″) and excellent thermal stability for all samples. These findings provide scientific basis for the utilization of gelatinous fungal polysaccharides as effective natural thickeners and stabilizers in food systems.