Integrated processes applied to cocoa bean hulls to obtain phenolic compounds and cellulose

Abstract

Abstract The cocoa bean hull is one of the main residues generated by the cocoa industry, accounting for approximately 10–20% of the total bean weight and resulting in large amounts of discarded biomass, which is rich in valuable components, including phenolic compounds (PC) and cellulose. This study aimed to valorize cocoa bean hull through the extraction of PC and cellulose using an eco-friendly approach and to propose the utilization of this residue by integrated processes resulting in value-added biobased products. For PC extraction, raw cocoa bean hulls (RCBH) and autoclave pretreated cocoa hulls (PTH) were subjected to a heat-assisted extraction (HAE) with water and to an ultrasound-assisted extraction (UAE) with water or 50% ethanol, while cellulose-rich materials were obtained by peracetic acid treatment. HAE applied to RCBH provided the highest PC content (16.67 mg GAE/g db) and antioxidant capacity, reaching 48 mg TE/g db by DPPH and 156 mg TE/g db by ABTS. Peracetic acid treatment promoted substantial delignification, increasing cellulose contents from 25.06 to 40.48% in the starting materials to 46.87–69.20% in the corresponding cellulose-rich fractions. The extracted materials exhibited increased crystallinity, reaching 74.4%. Overall, the results support further investigation of cocoa bean hull as a feedstock for integrated recovery of PC and cellulose, although process scalability, environmental impacts, economic feasibility, and valorization of the remaining fractions require further evaluation.