Abstract: Ultrasonic extraction method was adopted to extract polysaccharide from the dissepiments of Wu walnut from Three Gorges Reservoir area.On the basis of single factor test,response surface analysis with 3 factors including ultrasonic power,ultrasonic treatment time and solid-to-liquid ratio on the extraction yield of polysaccharide was adopted.Meanwhile,the antioxidant activity of the extracted polysaccharide was tested.The results showed that,the optimal extraction conditions were as follows:ultrasonic power of 310 W,ultrasonic time of 87 s and solid-to-liquid ratio of 1:24 (g/mL),the predicted value and measured value of the dissepiments polysaccharide were 26.94 mg/g and 24.88 mg/g,respectively.The antioxidant activity testing results showed that,the dissepiments polysaccharide from Wu walnut had strong radical scavenging activity and reducing capacity,the EC₅₀ of DPPH and ABTS+ assays were 1.91 mg/mL and 1.21 mg/mL,respectively.

Key words: dissepiments crude polysaccharide, ultrasonic extraction, response surface method, antioxidant