Comparative study of different cocoa ( Theobroma cacao L.) clones in terms of their phenolics and anthocyanins contents

Abstract

Polyphenols were analysed at 280 nm by HPLC device using a Photodiode Array Detector (PDA). Anthocyanins were separated with the SEP-PAK Vac 6cc 1000 mg (Waters) column and measured at 520 nm with a PDA. Nineteen cacao clones from Cameroon genebank were analysed. Fresh and fermented-like seeds were used. Two main polyphenols were present in our samples: catechin and epicatechin. Epicatechin represents 2–4% DM of defatted cocoa seed powder. Undefined substances called A, B and C were also found in cocoa seeds. Substance A is discussed as a derivative of caffeic acid and an ester-bound compound. Substances B and C are oligomeres of proanthocyanidins. Protocatechiuc acid and quercetin were not detected. Two anthocyanins were found in cocoa seeds: cyanidin-3-galactoside and cyanidin-3-arabinoside. They represent 0.02–0.4% DM of defatted cocoa seed powder. Total phenols, catechin, epicatechin and anthocyanin in fresh and fermented-like beans were genotype-dependent. Polyphenols from seeds of two different pods from the same clone showed a quantitative significant difference. Spearman's correlation test showed that there is no correlation between the number of seeds per pod, weight of pod and content of polyphenolic compounds. Nevertheless, a negative correlation was found between the number of seeds per pod and the catechin content ( r = - 0.4 6 3 , P < 0.0 1 ). Groupings of samples were observed using PCA and hierarchical cluster analysis. The separation between groups is related to their polyphenol and anthocyanin contents.