Abstract: In order to improve the utilization rate of Asparagus officinalis L. scraps, ultrasonic assistance was applied for the extraction of saponins from the materials. After two rounds of uniform design, the optimal extraction conditions for achieving maximum extraction rate of saponins were material-to-liquid ratio of 1:1 (m/V), extraction temperature of 30 ℃, duty cycle of 0.4:1.6 (ratio of occupied to empty space), ultrasonic power of 200 W, extraction time of 30 min, extraction pH of 5.05 and ethanol concentration of 70%. Under the optimal conditions, the extraction rate of saponins was up to 7.5%, and the recovery rate was 98.78% after three rounds of extraction. The saponins could be fully recovered by three rounds of extractions in a 2 L circulated ultrasonic-assisted extraction device. Therefore, ultrasonic-assisted extraction is suitable for the extraction of saponins from Asparagus officinalis L. scraps.

Key words: Asparagus officinalis L., steroid saponins, uniform design, ultrasonic circulation extraction