Valorization of Cocoa Pod Husk Through Integrated Drying and Probe Ultrasound-Assisted Extraction: Effects on...

Cocoa pod husk, a major agro-industrial by-product of cocoa processing, represents an underutilized source of phenolic compounds with potential functional applications. This study developed an integrated extraction process combining drying pretreatments with probe ultrasound-assisted extraction to enhance the recovery and bioactivity of cocoa pod husk extracts. Preliminary solvent screening identified aqueous ethanol (1:3, v/v) as the most suitable extraction solvent, and a solid-to-solvent ratio of 1:9 (w/v) was subsequently selected for further extraction experiments. Under these extraction conditions, the type of drying pretreatment (tray drying or vacuum microwave drying), ultrasonic amplitude, and extraction time influenced the total phenolic content, phenolic composition, and antioxidant activities (DPPH, ABTS, and FRAP) of cocoa pod husk extracts. The evaluated extracts exhibited antibacterial activity against Streptococcus mutans. Cellular assays were performed using two selected extracts: Cocoa-A (vacuum microwave-dried) and Cocoa-B (tray-dried), which were prepared with aqueous ethanol (1:3, v/v) at a solid-to-solvent ratio of 1:9 (w/v) under 75% ultrasonic amplitude for 15 min. These extracts contained total phenolic contents of 5.41 ± 0.14 and 5.01 ± 0.14 mg GAE/g dried cocoa pod husk for Cocoa-A and Cocoa-B, respectively. Both extracts showed low cytotoxicity together with reduced intracellular reactive oxygen species and suppression of lipopolysaccharide-induced inflammatory mediators, including nitric oxide, IL-6, and TNF-α. The tray-dried extract (Cocoa-B) exhibited greater anti-inflammatory activity than the vacuum microwave-dried extract (Cocoa-A), indicating that the drying pretreatment influenced the biological activity of the extracts. This difference may also be associated with variations in phenolic composition, although the contribution of individual phenolic compounds was not investigated in the present study. These findings improve the understanding of how drying pretreatment and probe ultrasound-assisted extraction parameters influence the recovery of bioactive compounds from cocoa pod husk and provide a scientific basis for the further development of cocoa pod husk-derived bioactive ingredients for functional food, nutraceutical, and oral health-related applications.