Ultrasound-assisted extraction of total saponins from wild bitter melon (Momordica charantia L. var. abbreviata Ser.) with response surface methodology and kinetic analysis

Wild bitter melon, indigenous in Vietnam, showed a diversified profile of bioactive compounds, especially saponin, making it an attractive target for industrial extraction. Novel methodology for extracting saponins is crucial to improve the product’s potential. In this study, the combination of ultrasonic-assisted extraction and response surface methodology (RMS), fortified by kinetic analysis, was applied to determine the optimal conditions for the extraction of total saponin content (TSC). The single-factor analysis revealed the optimal range of three key factors – solvent/sample ratio (15:1, 20:1, and 25:1 mL/g), ultrasonication time (15, 20, and 25 min), and temperature (50, 60, and 70°C) – which was used in the Box–Behnken design. The kinetic analysis showed that the Luong kinetic model captured both the maximum TSC and the decline trend during different extraction periods, with a maximum TSC of 78.42 mg/g during an extraction time of 4.15 h. The RSM for 2-h extraction procedure suggested an optimal condition for saponin extraction with a solvent/sample ratio of 26.89 mL/g, a temperature of 66.22 °C, and an ultrasound time of 21.33 min. This profile resulted in TSC of 82.92 mg/g, and was confirmed by experimental data. This study integrated kinetic modeling with RMS for improving the saponin extraction process from the indigenous wild variety of M. charantia var. abbreviata collected in the northern region of Vietnam.