Abstract:To reduce plant resource waste and improve the economic benefits of the red pitaya industry， this study focused on the efficient extraction of polysaccharides from red pitaya peel. Polysaccharides were extracted using the ultrasound-assisted water-soluble alcohol precipitation method， with their extraction ratio as the evaluation index. Extraction conditions were optimized through single-factor and response surface methodology， and the antioxidant activity of the extracted polysaccharides was determined. The results indicated that the optimal extraction process for polysaccharides from red pitaya peel was an ultrasonic time of 41 min， an ultrasonic temperature of 62 ℃， and a solid-to-liquid ratio of 1∶39 （g/mL）， which yielded a maximum extraction ratio of crude polysaccharides at 15.47%. The concentration of crude polysaccharides from red pitaya peel showed a positive correlation with the scavenging activity of 1，1-diphenyl-2-picrylhydrazyl （DPPH） radicals and hydroxyl radicals （·OH）. Within the tested range， at a crude polysaccharide concentration of 4.0 mg/mL，the scavenging activity of DPPH radicals and hydroxyl radicals was 46.77% and 78.42%， respectively.