Central composite experimental design for ultrasound‐assisted extraction optimization of alkaloid compounds and antioxidant properties from cocoa pod husk ( Theobroma cacao L.)

Abstract

The objective of this research was to identify ultrasound-assisted extraction (UAE) parameters for maximizing alkaloid yield and antioxidant activity from cocoa pod husk (CPH). The findings indicated that the optimum UAE parameters were extraction temperature 60°C, extraction time 50 min, and solvent to sample ratio 50 ml/g. Under these UAE parameters, total alkaloid content (TAC), alkaloid extraction efficiency (AEE), DPPH radical scavenging capacity (DRSC), and ferric reducing antioxidant power (FRAP) obtained from the CPH were 45.62 mg AE/g dried sample (DS), 63.28%, 16.57, and 2.15 mg TE/g DS, respectively, which were not significantly different (p < .05) from the predicted values (42.57 mg AE/g DS, 59.04%, 15.06 and 0.99 mg TE/g DS, respectively). The residual moisture, water activity, density, water soluble index, and pH of enriched-alkaloids powder from the CPH were 7.66%, 0.39, 0.13 g/ml, 93.77%, and 5.08, respectively. TAC, total phenolic content (TPC), total flavonoid content (TFC), and total saponin content (TSC) of powder were 655.43 mg AE/g DS, 33.60 mg GAE/g DS, 48.51 mg CE/g DS, and 186.48 mg EE/g DS, respectively. ABTS radical scavenging capacity (ARSC), DRSC, cupric reducing antioxidant capacity (CUPRAC) and FRAP of powder were 84.48, 49.54, 155.01, and 6.01 mg TE/g DS, respectively. The results achieved from this study imply that the powder obtained from the CPH is a rich source of alkaloids. Thus, it is a potential candidate for application in the functional food and nutraceutical industries. Practical applications Cocoa pod husk is generated in huge amounts and is a rich source of alkaloids. Recovery of alkaloids from the CPH for potential application in the functional foods and nutraceuticals not only increases value for cocoa tree but also reduces pollution risk to environment.