The Effects of Different Extraction Methods on the Yield, Microstructure, and Antioxidant Activity of Polysaccharides from Rhodomyrtus tomentosa Berry

Extraction of polysaccharides from Rhodomyrtus tomentosa berry (RTP) is essential for understanding their bioactive ingredients and developing functional foods and pharmaceuticals. This study aimed to evaluate the effects of ultrasonic-assisted enzymatic extraction (UAE) and microwave-assisted enzymatic extraction (MAE) on the yield, physicochemical properties, and antioxidant activity of RTP. The results revealed that the optimal conditions for RTP extraction using the UAE were as follows: liquid-solid ratio 35 ml/g; ultrasonic time of 11 min, ultrasonic power of 240 W, and complex enzyme dosage of 2.5%. Under these conditions, the extraction yield was 35.67 +/- 0.32%. The FTIR results indicated that the two extraction methods did not affect the functional groups of the polysaccharides. The scanning electron microscopy results indicated that the surface of the UAE-extracted samples showed folds, fibrous structures, and a large number of small pores, which may be more effective in releasing the polysaccharides. Whereas the sample surface was smoother after MAE treatment. The ABTS radical scavenging ability of UAE was significantly higher than that of MAE. This study demonstrated that the UAE method is a promising method for extracting high-quality RTP based on its high yield, high efficiency, and outstanding antioxidant activity.