Investigation on the effects of drying methods on the structure and antioxidant activity of Tremella fuciformis polysaccharides using asymmetrical flow field‐flow fractionation

Polysaccharide is an important bioactive component in Tremella fuciformis (T. fuciformis). In this study, the effects of three drying methods (i.e., vacuum freeze-drying, microwave drying, and hot air drying) on the structure in terms of molecular weight (Mw) and radius of gyration, and conformation of T. fuciformis polysaccharide (TFP) were investigated by asymmetrical flow field-flow fractionation coupled online with multiangle light scattering and differential refractive index detectors. The physicochemical properties of TFPs were studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry. Furthermore, the structure-antioxidation relationship of TFPs was investigated. Results revealed that three drying methods did not significantly affect functional groups, crystal structure, and thermal property of TFPs but led to some differences in the morphology and Mw of TFPs. The TFP obtained by microwave drying had the highest DPPH radical scavenging activity, which could be attributed to low Mw. Novelty impact statement The three drying methods (i.e., vacuum freeze-drying, microwave drying, and hot air drying) studied in this work did not affect the functional groups and thermal properties of T. fuciformis polysaccharides (TFPs), but significantly affected the morphology of TFP granules and the Mw distribution of TFP molecules. TFP-M had the smallest Mw (1.36 ± 0.10 × 107 g/mol), which could be beneficial to its DPPH radical scavenging activity.