Abstract:Ultrasonic-assisted inner ebullition method was selected to extract pigment from the peel of Eleocharis tuberosa.The extraction conditions，including liquid-solid ratio，power，temperature，and time，were optimized by single-factor and response surface experiments.Additionally，the stability and antioxidant activity of the pigment in the peel of Eleocharis tuberosa were preliminarily investigated.The optimal extraction conditions were determined to be as follows:liquid-solid ratio of 50∶1（mL/g），power of 280 W，temperature of 60 ℃，and time of 20 min.Moreover，under these optimal extraction conditions，the theoretically predicted absorbance value of the pigment in the peel of Eleocharis tuberosa was 0.921.The stability test indicated that the absorbance of the pigment partly decreased in acidic conditions，whereas its color intensity was enhanced in alkaline conditions.Furthermore，the pigment in the peel of Eleocharis tuberosa had higher antioxidant activity，and its hydroxyl radical clearing rate could reach 97.38%.