Pectin Extraction from Residues of the Cocoa Fruit (Theobroma cacao L.) by Different Organic Acids: A Comparative Study

Ecuador is the world's fifth largest cocoa producer, generating hundreds of annual tons of residues from this fruit. This research aims to value this residual (cocoa pod husk) by using it as raw material to obtain pectin, which is widely used in the food and pharmaceutical industries. For them, the extraction of three different organic acids with GRAS status (and therefore safe for their use), citric, malic and fumaric acids, were studied. In addition, two other factors, temperature (70-90°C) and extraction time (60-90 min), were explored in a central composite design of experiments. Under the conditions of the experiment, it was obtained that the best yields were reached for citric acid, malic acid and fumaric acid and for ~86 min of extraction time. The temperature did not show a significant influence on the yield. The pectins obtained under optimal conditions were characterised, showing their similarity with commercial pectin. However, the equivalent weight and the esterification degree of the pectin obtained with fumaric acid classify it as having a high equivalent weight and a low degree of esterification. It differs significantly from the other two acids, perhaps due to the limited solubility of fumaric acid.