The effects of different extraction methods on the yield, microstructure, and antioxidant activity of polysaccharides from Rhodomyrtus tomentosa berry

Abstract Extraction of polysaccharides from Rhodomyrtus tomentosa berry (RTP) is essential for understanding their bioactive ingredients and developing functional foods, nutraceuticals, 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 single-factor and orthogonal experimental design revealed that the optimal conditions for ultrasound assisted RTP extraction are at liquid to solid ratio of 35 mL/g, ultrasonic time of 11 min, ultrasonic power of 240 W, and complex enzyme dose of 2.5% with RTP extraction yield of 35.67 ± 0.32%. FT-IR spectroscopy showed that UAE caused less disruption of the polysaccharide molecular structure and better retention of functional groups than MAE. The scanning electron microscopy results demonstrated that the ultrasonically treated samples exhibited a greater degree of structural disruption, which could more effectively facilitate the release of polysaccharides. In addition, RTP obtained by the UAE has a better extraction yield and ABTS radical scavenging activity than MAE. This study demonstrated that the UAE method is a promising method for extracting high-quality R. tomentosa berry polysaccharides based on its high yield, high efficiency, and outstanding antioxidant activity.