Influences of subcritical water extraction on the characterization and biological properties of polysaccharides from Morchella sextelata

Subcritical water extraction (SWE) and hot water extraction (HWE) were used to extract polysaccharides from Morchella sextelata (MSP). The physicochemical and structural characteristics and biological properties of MSPSWE and MSPHWE were evaluated. SWE achieved a higher crude MSP yield (18.09 ± 0.09%) than HWE (4.95 ± 0.05%; p < .01). Using SWE, MSPSWE showed a higher total sugar content and fat-binding capacity. MSPSWE and MSPHWE contained the same monosaccharides, but with significantly different average molecular weights and microstructures without alterations in the main chemical structure, as revealed via FT-IR and nuclear magnetic resonance (NMR) spectroscopy. DSC analysis revealed favorable thermal stability. Biological activity assays elucidated that MSPSWE had stronger antioxidant activity in vitro and significantly promoted RAW264.7 cell proliferation and nitric oxide production. Therefore, MSPSWE may represent a potent antioxidant and immunomodulator in the functional food field, with SWE serving as an effective method for extracting highly bioactive M. sextelata polysaccharides. Novelty impact statement The molecular weight of Morchella sextelata polysaccharides (MSPs) decreased following subcritical water extraction (SWE), which also improved their yield (from 4.95% to 18.09%). Furthermore, the MSPs obtained via SWE showed stronger antioxidant and immunomodulatory activities than those obtained via hot water extraction.