Microwave-Assisted Extraction of Phenolic Compounds from Cocoa Pod Husk: Process Optimization and Impact of Drying Temperature on Bioactive Recovery

Cocoa pod husk (CPH), the principal by-product of cocoa processing, represents an abundant and underutilized source of bioactive phenolics with potential applications in the food and nutraceutical sectors. This study optimized the extraction of catechin, epicatechin, procyanidin B2, and clovamide from CPH (CCN-51 variety) using microwave-assisted extraction (MAE) and evaluated the influence of drying temperature on their retention. A Box-Behnken design within a response surface methodology framework was employed to evaluate the effects of ethanol concentration (0-100%), extraction temperature (50-150 °C), and extraction time (15-60 min) on compound recovery. The phenolic profile was characterized by high-performance liquid chromatography with diode-array detection and electrospray ionization ion trap tandem mass spectrometry. Optimal MAE conditions of 51% ethanol, 104 °C, and 38 min yielded maximum concentrations of clovamide, procyanidin B2, and epicatechin of 3440, 908, and 445 mg/kg dry matter of cocoa pod husk, respectively. Drying studies demonstrated that moderate hot-air temperatures (40-50 °C) preserved the highest phenolic levels. These results underscore the importance of optimizing both extraction and drying conditions to enhance the recovery of phenolic compounds from cocoa processing residues, supporting their potential valorization as antioxidant-rich functional ingredients.