Microwave-assisted extraction for optimizing saponin yield and antioxidant capacity from cacao pod husk (Theobroma cacao L.)

This study aimed to optimize microwave-assisted extraction (MAE) parameters for saponins from cacao pod husk (CPH). The results showed that the optimal MAE parameters for obtaining the highest saponin content (SC) and saponin extraction efficiency (SEE) from the CPH were 85% methanol concentration, 600 W microwave power, 6 s/min irradiation time, 40 min extraction time, and 50 ml/g solvent to sample ratio. Under these optimal parameters, the measured values for SC and SEE were 69.9 mg EE/g dried sample (DS) and 71.1%, respectively. The powdered CPH extract obtained under the optimal MAE parameters and freeze drying had moderately low water activity (0.52) and high water soluble index (88.58%). The powdered CPH extract possessed high saponin and flavonoid contents (402.74 mg EE/g DS and 115.50 mg CE/g DS, respectively), which displayed potent antioxidant capacity with DPPH radical scavenging capacity and ferric reducing antioxidant power of 348.67 mg DPPH/g DS and 64.88 mg Fe(II)/g DS, respectively. Therefore, the optimal MAE parameters of 85% methanol, 600 W, 6 s/min, 40 min, and 50 ml/g are recommended for extraction of saponins from the CPH for further investigation and application. Practical applications Cacao pod husk is generated a huge amount in cacao processing industry, which is considered as a potential source for exploitation of bioactive compounds, particularly saponins for application in the nutraceutical and functional foods industries. This strategy helps to increase the economic value for cacao tree as well as reduce the risk for environmental pollution, toward sustainable development.