Cocoa processing residues in a circular bioeconomy: integrated valorization pathways, applications, and future perspectives

Cocoa (Theobroma cacao L.) is a major tropical cash crop that generates large volumes of underutilized residues, including cocoa pod husks (CPH), cocoa bean shells (CBS), mucilage, and placenta tissues. These residues are generally dumped in the open field where they constitute environmental challenges, especially in the West African region, where cocoa production is dominant, with an annual estimated yield of 40–50 million tonnes CPH and nearly one million tonnes CBS. However, these residues can be integrated into the bioeconomy through valorization. This review synthesizes current knowledge on cocoa residue generation, composition, and its possible applications in different sectors. Analyses showed that cocoa residues are rich in phytochemicals such as polyphenols, flavonoids, methylxanthines, high in dietary fibres, and essential minerals, making them good antioxidants and antimicrobial agents. These components confer techno-functional properties suitable for food, nutraceutical, cosmetic, and pharmaceutical applications. Emerging valorization pathways include bioenergy production (biochar, biogas, briquettes, and bioethanol), functional food ingredients, cosmetics, renewable packaging materials, and agricultural inputs (organic fertilizers, mulches, animal feed after detoxification). Innovative approaches for effective valorization and sustainability, such as extraction, fermentation, and thermochemical processing, were explored. However, the presence of toxic theobromine, mycotoxins, heavy metals, high moisture content (perishability), and inadequate infrastructure for cocoa waste handling remain serious challenges, especially in West Africa. Pretreatment technologies, regulatory frameworks, and integrated biorefinery approaches manage these challenges for effective valorization. Overall, cocoa residue valorization into high-value products supports sustainable agriculture, rural income diversification, waste reduction, and the realization of a circular bioeconomy, which contributes to all SDGs, and is most impactful for SDGs 8, 12, and 13.