Comparison of two extraction methods for saponins from asparagus old stalk

The extraction of saponins from the old stalk of asparagus was optimized by employing quadrature experimental design. Ultrasonic wave assisted extraction was selected as an optimal method with the advantages of efficiency,safety,low cost,and non-damage of saponins. The optimal ultrasonic wave assisted extraction conditions were solvent of 60% ethanol,temperature at 50 ℃,extraction time of 50 min,and the ratio of material to solvent at 1∶35. Under the optimal conditions,the content of saponis in the ultrasonic wave assisted extraction was over 5.01%,being 129.3% than that by digestion extraction.