Abstract: The optimal processing conditions for ultrasonic extraction of pigment form leaves of Vacciniun bracteatum Thunb. were obtained by single factor and orthogonal tests. The results are: 30 kHz ultrasonic wave, 62% (volume fraction) ethanol as solvent, the ratio of liquid to material is 3.5:1 (mL:g), extracting once for 10 min at room temperature. Ultrasonic extraction has a prime superiority over traditional one. The yield of ultrasonic extraction under optimal processing conditions is 23.84%, higher than that of traditional extraction 11.43%. Furthermore,ultrasonic extraction has advantages of shorter duration, less solvent and energy consumption, and improved quality of products. Moreover, the pigment is stable at pH value<7.0 and temperature below 80℃. Sucrose has little effect on the stability of pigment while citric acid has considerable positive effect on increasing the color and luster, and keeping the stability of pigment. Sodium benzoate and potassium sorbate degrade the pigment quite obviously when their mass fraction are more than 0.01%.

Key words: ultrasonic extraction, Vaccinium bracteatum Thunb., pigment