From cocoa waste to sustainable bioink: valorising pectin for circular economy-driven tissue engineering

Cocoa bean production, a cornerstone of many developing economies, currently adheres to a linear economic model, giving rise to sustainability concerns. The expansion of cocoa butter and liquor consumption has resulted in the increased generation of residual biomass, constituting 60–70 % of fresh fruit. The absence of management plans for this biomass in cocoa-producing countries poses a risk of phytosanitary issues. This study proposed a circular economy approach by valorising cocoa pod husk-derived pectin for tissue engineering. The study optimised an alkaline-based protocol to extract pectin from cocoa pod husk, resulting in ∼ 20 % yield with a ∼ 47 % degree of esterification. Methacrylation transformed extracted pectin into pectin methacrylate (PECMA), confirmed by FTIR-ATR and NMR analyses. PECMA hydrogels, crosslinked with CaCO₃ and UV, exhibited rapid gelation and superior water uptake properties. SEM revealed distinct morphological differences with UV exposure, showing improved interconnectivity and anisotropic porosity while the mechanical testing demonstrated enhanced compressive modulus and rheological properties with UV crosslinking. PECMA-based bioink encapsulated chondrocytes, maintaining cell viability over 6 days. This innovative bioink, derived from cocoa waste, holds promise for sustainable tissue engineering applications.