Sustainable Bioethanol Production from Cocoa Pod Husk with and Without Reductive Catalytic Fractionation (RCF)

The urgent need to reduce greenhouse gas emissions has driven the search for sustainable alternatives to fossil fuels. In this context, cocoa residues emerge as a promising feedstock for bioethanol production. This study evaluated the influence of a catalytic biorefinery treatment on the bioethanol production potential from cocoa pod husks. Both raw and catalytically treated biomass were characterized using SEM, pore size distribution analysis, and TGA. Subsequently, enzymatic hydrolysis was performed using various cellulase and hemicellulase loadings, followed by anaerobic fermentation with Saccharomyces cerevisiae. Bioethanol production was modeled using the modified Gompertz equation. The results evidenced changes in the structure and composition of the lignocellulosic matrix following catalytic treatment, increasing surface area and reducing hemicellulose content. Although total sugar release during hydrolysis was comparable between the two samples, the biomass processed via the catalytic biorefinery promoted higher sugar consumption and bioethanol concentration, reaching 3.36 g/L with a yield of 112 g kg−1 of dry biomass. The kinetic model showed a strong fit (R2 between 0.94 and 0.97). These findings demonstrate that the integration of catalytic biorefinery, enzymatic hydrolysis, and fermentation constitutes a viable alternative for the valorization of cocoa residues.