Effects of Ultrasound-Assisted Extraction on Yield, Physicochemical Properties, and Structural Characterization of Rosa laevigata Polysaccharides: A Comparative Analysis with Five Conventional Methods

This study systematically compared ultrasound-assisted extraction (UAE) with five other methods (hot water extraction (HWE), microwave-assisted extraction (MAE), acid extraction (FTACP), alkali extraction (FTAIP), and enzyme-assisted extraction (EAE)) for their effects on the yield, physicochemical properties, and bioactivities of <i>Rosa laevigata</i> Michx. polysaccharides. The results demonstrated UAE's superior performance: it achieved a higher polysaccharide yield (31.27%) than HWE, FTACP, and FTAIP, approaching that of MAE and EAE. SEM observation revealed that UAE-derived polysaccharides exhibited a uniform porous network with smooth surfaces and excellent dispersibility, outperforming the irregular aggregates or structural loosening observed in other methods. Notably, UAE polysaccharides showed remarkable cholesterol-binding capacity (31.18 mg/g) and FRAP reducing power (0.0423 mmol/g), which highlights their potential for functional food applications. Structural analyses (FT-IR, XRD, TGA) confirmed that UAE better preserved the native conformation and thermal stability of polysaccharides, whereas chemical (FTACP/FTAIP) and high-temperature (MAE) methods induced molecular degradation. In conclusion, UAE, as an eco-friendly and low-denaturation technique, offers an optimal strategy for the high-value utilization of <i>R. laevigata</i> polysaccharides.