Comparison of different extraction methods for polysaccharides from Dendrobium officinale stem

The purpose of this study was to screen the optimum extraction of polysaccharides (DOP) from Dendrobium officinale stem. Firstly, different methods, including hot water extraction (HWE), cold-pressing (CP), freeze-thawing cold-pressing (FTCP), ultrasonic-assisted hot water extraction (UHWE), microwave-assisted hot water extraction (MHWE) and enzyme-assisted hot water extraction (EHWE), were employed to extract DOP under their respective best parameters. Then, the extraction yield, structure and antioxidant activity of the polysaccharides from different extraction methods were compared under the same condition. The data implied that UHWE and FTCP possessed higher extraction yield than the other extraction methods. Besides, DOP CP and DOP FTCP had higher molecular weight than the other polysaccharide samples. More importantly, DOP FTCP had the highest antioxidant activity. Overall, DOP FTCP exhibit high extraction yield, well-preserved molecular chains and best antioxidant activity, all these indicated FTCP was the most suitable method to extract DOP.