Activated carbons made from cocoa ( Theobroma cacao ) and coconut ( Cocos nucifera ) shells can be used as adsorbents to improve the quality of frying oils

Abstract

This research study aimed to evaluate the ability of activated carbons derived from cocoa and coconut shells to eliminate oxidation products and regenerate frying oils. The powders were activated, after which they were carbonised at various temperatures. The resulting activated carbons were characterised using the Boehm and methylene blue method. The best adsorbent activated carbons, as well as their mixtures, were used to treat/filter oxidised oils collected after 8, 16 and 24 frying cycles. The primary (hydroperoxides) and secondary (aldehydes) oxidation products and the free fatty acids were quantified before and after treatment using standardised methods. A sensory evaluation of doughnuts fried in the filtered oils was also conducted. The results of the study demonstrate that carbonised cocoa shells (CoAS) at 300°C and carbonised coconut shells at 200°C exhibit superior porosity, a substantial adsorption surface area and a high proportion of acidic functions (34.4%–35%). Activated carbons made from CoAS and from the mixture cocoa–coconut shells at 15% demonstrated their ability to reduce impurities (hydroperoxides, aldehydes) in frying oil and to improve organoleptic properties of deep‐fried products. This study can be used as a benchmark for the valorisation of these agricultural by‐products in the production of natural adsorbents for oil regeneration.