Abstract:The ultrasound-assisted ethanol extraction method was used to extract the total polyphenols from highland barley spent grains.Four factors，including ultrasound temperature，solid-liquid ratio，ultrasound time，and ultrasound power，were selected to explore their effects on the yield of total polyphenols from highland barley spent grains through single-factor experiments.Then the optimal extraction process was optimized by orthogonal experiments，and the antioxidant properties of total polyphenols from highland barley spent grains were evaluated by in vitro antioxidant assays.The results showed that the optimal extraction process for highland barley spent grains polyphenols was as follows：ultrasound time of 50 min，ultrasound power of 400 W，ultrasound temperature of 45 ℃，and solid-liquid ratio of 1 ∶20（g/mL）.Under those conditions，the extraction rate of total polyphenols from highland barley spent grains was（3.337 1±0.149 8）mg/g.Furthermore，in vitro antioxidant activity assays demonstrated that highland barley spent grains polyphenols had good scavenging effects on DPPH·，·OH and·O2-，with clearance rates of（83.76±1.35）%，（52.05±2.09）%，and（76.88±1.47）% at a concentration of 21 μg/L，respectively.