Effects of multi-mode divergent ultrasound pretreatment on the physicochemical and functional properties of polysaccharides from Sagittaria sagittifolia L

The aim of this study was to investigate the physicochemical and functional properties of polysaccharides from Sagittaria sagittifolia L. (SSP), extracted by the assistance of multi-mode divergent ultrasound (SSU), with different frequencies (20, 28, 40 kHz) and various combinations (20/28, 20/40, 28/40, 20/28/40 kHz). The results showed that, compared with hot water extraction, multi-mode divergent ultrasound assistance extraction (MDU) not only improved the yield of SSP (SSU-28/40 increased by 43.47%) with lower Mw and higher uronic acid content, but also changed its morphology (p < 0.05). In addition, all SSPs extracted by MDU are hetero-polysaccharides with triple helix structure, which contain different molar ratios of rhamnose, arabinose, xylose, mannose, glucose and galactose. Moreover, these polysaccharides displayed higher foam capacity, foam stability, thermal stability, significant scavenging on DPPH, ABTS and hydroxyl radicals, and better inhibitory effects on HepG2 and MCF-7 cells in vitro. These results indicated that MDU may contribute to the degradation of polysaccharides, promote the transformation of monosaccharide, and improve the yield, solubility, antioxidant activity, and anti-tumor activity of SSP, suggesting that MDU has great potential application prospects in food, medicine, cosmetics and other fields.