Abstract:To optimize the extraction process of total flavonoids from yellowed rice and evaluate their antioxidant activity，with yellowed rice as the raw material，an ultrasound-assisted extraction method was employed.The extraction rate of total flavonoids was used as the evaluation index to investigate the effects of different raw material pretreatment methods（swelling and grinding，grinding with a liquid nitrogen grinder，and grinding with a high-speed crusher）and different solvents（water，methanol，ethanol，and ethyl acetate）on the extraction effects. The results indicated that grinding with a liquid nitrogen grinder was the optimal pretreatment method，and ethanol was the best extraction solvent. Furthermore，through single-factor experiments and Box-Behnken response surface methodology，the optimal extraction conditions were determined as follows：extraction temperature of 50 ℃，solid-liquid ratio of 1∶58（g/mL），ethanol volume fraction of 83%，shaking time of 46 min，and ultrasonic time of 69 min. Under these conditions，the extraction rate of total flavonoids reached 9.66%.The yellowed rice demonstrated good antioxidant activity，and the antioxidant properties of its flavonoid extract were significantly higher than those of non-yellowed rice.