Ultrasound-assisted extraction of saponins from mustard greens (Brassica juncea)

This study investigates the effects of operating parameters on ultrasound-assisted extraction of saponins from mustard greens (Brassica juncea). Single-factor experiments revealed clear optimum ranges for extraction time, ultrasound amplitude, solid-to-solvent ratio, and ethanol concentration. Total saponin content reached 27.10 ± 0.01 mg/g DW after 20 minutes of ultrasonication and 25.78 ± 0.01 mg/g DW at 50% amplitude, while further increases reduced extraction efficiency, likely because of compound degradation. A solid-to-solvent ratio of 1:25 (w/v) yielded 46.13 ± 0.01 mg/g DW. In the ethanol–water system, 70% and 80% ethanol achieved the highest extraction efficiencies, at 59.31 ± 0.01 and 59.12 ± 0.01 mg/g DW, respectively. These findings provide a scientific basis for subsequent optimization of saponin recovery from mustard greens.