Subcritical water extraction improves the ability of Auricularia cornea var. Li. Polysaccharides to stabilize hydrogels and emulsion gels.

In this work, polysaccharides from Auricularia cornea var. Li. (ACP) were extracted by a novel subcritical water extraction (SWE) method. Their structural properties and ability to stabilize hydrogels and emulsion gels were investigated and compared with those obtained by the conventional hot water extraction (HWE) method. The results showed that the polysaccharide yield of SWE (45.11 ± 0.23 %) was higher than that of HWE (17.85 ± 0.51 %). The two polysaccharides had the same type of monosaccharides but different compositions, and the molecular weight of ACP-SWE was slightly lower. The molecular conformation of ACP-HWE exhibited a long-chain structure, whereas ACP-SWE was multi-branched with obvious entanglements between the molecular chains. Both polysaccharides were able to form gels at concentrations above 1.0 %, with the ACP-SWE hydrogel having a denser network structure with better rheological and textural properties. ACP-SWE also had a greater ability to stabilize emulsion gels. By adjusting the polysaccharide concentration (c, 0.2 %-1.0 %) and the oil phase volume fraction (φ, 0.4-0.8), ACP-SWE emulsion gels could be prepared in a single step of shear homogenization. This work revealed that the adsorption of ACP-SWE at the oil-water interface and cross-linking in the bulk phase, together with the filling effect of oil droplets, contributed to the stabilization of ACP-SWE emulsion gels.