Ascorbic acid-assisted extraction of bioactive pectin from cocoa and coffee husks with antioxidant and anti-inflammatory potential

Pectin, a multifunctional polysaccharide with food, pharmaceutical and biomedical applications, can be sustainably extracted from Theobroma cacao and Coffea arabica pod husk waste. This study optimized an eco-friendly, ascorbic-acid-assisted acid extraction to maximize galacturonic acid (GalA) content, achieving optimal conditions for cocoa (R= 0.02 g/mL, P= 45:55 v/v AA:HCl, T= 65 min) and coffee (R= 0.01 g/mL, P= 100:0 v/v AA, T= 65 min). The extraction yielded pectin with ≥74% GalA, meeting USP/FCC pharmaceutical-grade criteria, with cocoa and coffee husk yields of ∼7% and ∼21%, respectively. Dialysis increased purity, raising molecular weight up to ∼297,000 Da and narrowing dispersity. Extracted pectin exhibited higher total phenolic and flavonoid contents than commercial citrus pectin and showed superior antioxidant capacity (ORAC up to 53.1 mg TE/g; DPPH up to 2420 mg TE/g), supported by metabolomic profiling that identified abundant antioxidant metabolites such as protocatechuic acid, trigonelline and catechol. In vitro assays with human dermal fibroblasts demonstrated cytocompatibility at 0.1 mg/mL, mild ROS-scavenging effects and selective modulation of inflammatory cytokines, with cocoa pectin reducing IL-6 and dialyzed coffee pectin showing strong IL-6 suppression.