Effect of extraction methods on property and bioactivity of water-soluble polysaccharides from Amomum villosum.

•Four extraction methods were compared for extracting water-soluble polysaccharides (WSP) from A. villosum.•Samples from different extraction methods had the same monosaccharide composition.•Ultrasonic-assisted extraction had the highest yield of WSP.•WSP extracted by ultrasonic-assisted extraction had the best antioxidant activity.•Ultrasonic-assisted extraction was the best extraction method for WSP.