To investigate the effects of drying methods on the structure characteristics and immunomodulatory activity of polysaccharides derived from Morchella esculenta， fresh M. esculenta were separately subjected to hot-air drying (HD) and freeze drying (FD). Polysaccharides from M. esculenta (MEP) extracted from the two dried samples were purified by macroporous adsorption resin column chromatography， yielding HD-treated MEP (HMEP) and FD-treated MEP (FMEP). The monosaccharides of HMEP and FMEP were consisted of mannose， glucose and galactose while with different molar ratios of 1∶0.34∶0.33 and 1∶4.50∶0.02， respectively. HD treatment caused the break of C—O—C glycosidic linkages in polysaccharides chains and enhanced the abundance of α-configuration in polysaccharides from M. esculenta. Both HMEP and FMEP improved immunity by inducing phagocytosis and the secretions of NO， TNF-α， IL-6 and IL-1β of RAW 264.7 cells. At 50 μg/mL， FMEP stimulated RAW 264.7 cells to secrete NO at a level of (35.29±1.25) μmol/L， which was higher than that induced by HMEP [(28.05±2.52) μmol/L] and the model group [(32.47±1.30) μmol/L] at 50 μg/mL. At 25 μg/mL， FMEP stimulated macrophage TNF-α secretion to (289.96±49.00) ng/mL， which was higher than that of HMEP [(188.56±13.60) ng/mL] and the model group [(97.76±2.00) ng/mL]. This indicates that FMEP exhibited higher immunomodulatory activity than HMEP. After comprehensive consideration， freeze drying would be recommended as a suitable drying process for use in the preparation of immunomodulatory polysaccharides from M. esculenta as functional foods.

Morehella esculenta  /  polysaccharides  /  freeze drying  /  hot air drying  /  structural characteristics  /  immunomodulatory activity