Effects of Different Drying Methods on Structural Characterization, Rheological Properties, Antioxidant and Hypolipidemic Activities of Polysaccharides from Fig (Ficus carica L.)

In this study, figs were dried by hot air drying (HD), vacuum freeze-drying (FD), vacuum drying (VD) and far-infrared drying (FID). Four fig polysaccharides (FPs) were extracted from different dried figs, and the corresponding names were FPH, FPF, FPV and FPFI. The effects of different drying methods on the structural properties, rheological properties and biological activities of FPs were compared. The result shows that the extraction rate of polysaccharides after FD (2.49%) treatment was 58.60%, 50% and 28.35% higher than that of HD (1.57%), VD (1.66%) and FID (1.94%), respectively. Drying methods result in varying molar ratios of monosaccharides. FPFI has more stable gel properties. HD, VD and FID caused damage to the surface structure of the polysaccharides. FPF exhibited the highest uronic acid content (25.56%), along with relatively low apparent viscosity and molecular weight (1.45 × 105 Da), which contributed to its superior antioxidant and lipid-lowering activities. Therefore, FD is a drying method to obtain fig polysaccharide with high antioxidant and hypolipidemic activity. The results provided a scientific basis for the drying process of fig polysaccharide and a reference for the development of potential hypolipidemic products of fig polysaccharide.