Cocoa is among the most cultivated and important tropical crops in the world, and it is economically viable in the agro-pastoral systems of tropical Africa. Further, the amount of cocoa residue is steadily increasing due to the strong worldwide demand for chocolate products. This review of cocoa residue found that an average of 18 publications per year were published in the last 10 years. The most common type of publication on cocoa pod husks (CPH) was newspaper articles, which comprised 50% of the publications. This review examines the use of CHP in sustainable development, agrochemical materials, and agro-materials through their potential valorizations into high value-added products. Indeed, CPH is an abundant, accessible, and renewable resource of bioproducts, dietary fibers, nutraceuticals, functional foods, pectin, antioxidant compounds, theobromine, and minerals. Potential food applications of CPH include the production of flavor compounds, gums, texturing agents, and others. The production of biomaterials for food and non-food use, biofuels, and organic acids, such as lactic acid (the polymerization of which produces the PLA used in bioplastic production), are several potential areas for the biotechnological development of CPH and its fractions.

Cocoa pod husks are a type of biomass that is still poorly explored. This work was carried out as part of the optimization of the delignification process for this residue with potassium hydroxide, to maximize the reducing sugars content. Screening for potentially influencing factors showed that the biomass to solvent ratio and the temperature had the greatest effect on the delignification process. Optimization of these factors using a composite central plan revealed that the quadratic model was the most suitable for predicting the rate of delignification. The predicted R² (0.815) was in good agreement with the adjusted R² (0.906). The correlation coefficient (R2 = 0.945) between the predicted and experimental results confirmed the fit of the model. The optimal conditions were a biomass to solvent ratio of 9.14% and a temperature of 128 °C, which resulted in a maximum degree of delignification of 93.9%, with 80% of the solids recovered. This study found that the removal of extractables before the pretreatment considerably improved the delignification of cocoa pod husks and the production of reducing sugars, which increased from 3.15 ± 0.006 mg/mL to 5.33 ± 0.143 mg/mL. Scanning electron microscopy and X-ray diffraction confirmed physicochemical changes in the biomass after pretreatment.

The valorisation of agricultural residues into a high value-added product is necessary to respond to the global environmental concerns caused by the pollution of agricultural waste. The objective of this study was to shed light on a new value-added usage of cocoa pod husk (CPH) for the synthesis of cellulose triacetate (CTA). Alkaline treatment with sodium hydroxide (5 wt%) followed by bleaching process with (2 wt%) hydrogen peroxide was found effective for the extraction of cellulose from CPH. The percentage of cellulose obtained was 80.5% with a yield of 54%. The CTA was synthesised by a explore new way acetylation reaction in the presence of acetic acid, acetic anhydride, and sulphuric acid. The CTA obtained had a degree of substitution of 2.87 and a percentage of acetylated group of 43.8%, as determined by titration. The result of Fourier transform infrared spectroscopy showed the appearance of the stretching of the ester and the acetyl groups, indicating the formation of CTA. X-ray diffraction showed that the crystallinity index of CPH cellulose was 38.4%, while indicating the semi-crystalline nature of CTA produced. Scanning electron microscopy confirmed a change in the morphology of CTA after acetylation. X-ray energy dispersive analysis showed that the CTA was mainly composed of carbon and oxygen.