Roasting impact on the contents of clovamide (N-caffeoyl-L-DOPA) and the antioxidant activity of cocoa beans (Theobroma cacao L.)

The caffeoylated amino acid clovamide [(-)-N-[3'-4'-dihydroxy-(E)-cinnamoyl]-dihydroxyphenylalanine] was identified in the antioxidant polyphenolic fraction of cocoa (Theobroma cacao L.). As a naturally occurring caffcoyl conjugate, clovamide represents an interesting antiradical/antioxidant compound. We have streamlined the synthesis of clovamide, investigating the effect of roasting on its content in different samples of cocoa beans from different geographic origin. Within the samples analyzed, those from Ghana showed the highest clovamide content (2.637 mg/kg, powder from fermented beans, dry weight; 1.264 mg/kg, powder from roasted nibs, dry weight), while the Arriba samples showed the lowest values. A poor correlation existed between the contents of clovamide and the antioxidant properties of cocoa, while roasting caused a dramatic reduction in the clovamide contents (up to 59.13% in Arriba cocoa), paralleled by an overall decrease of the antioxidant properties, as measured by the DPPH method. Taken together, results show that while roasting is detrimental for the clovamide contents of cocoa, no correlation exists between the concentration of this compound and the overall antioxidant properties of cocoa samples, and suggest that clovamide is important but not critical for the antioxidant activity of cocoa. (C) 2007 Elsevier Ltd. All rights reserved.