Dynamics of volatile and non-volatile compounds in cocoa (Theobroma cacao L.) during fermentation and drying processes using principal components analysis

Different volatile and non-volatile compounds produced during the fermentation-drying process are considered as indicatives of cocoa beans quality. We found thirty-nine different compounds identified by SPME-HS/GC-MS and related to the desirable notes and off-flavor that have been reported. Volatile and nonvolatile compounds were associated with acidity and changes of pH, such as acetic and lactic acid. Using the principal component analysis (PCA), relations between compounds and fermentation and drying day were associated with dynamics of these compounds. The identification of principal compound produced during the fermentation and drying processes can be helpful in searching for off-flavor indicator and as a fermentation index, such as isobutyric, isovaleric and propionic acids. Oxidation of 3-methyl-1-butanol-to-3-methyl-1-butanol acetate can be of use in evaluating the degree of fermentation. At drying, the compounds with the highest levels were acetic and isobutyric acid, ethyl and 3-methyl-1-butanol acetate, pentanal and 2,3-pentanedione, and 1,3-butanediol and 2,3-butanediol. Therefore, acetic acid and isobutyric acid, due to their high levels and their low threshold value could play an important role in the aromatic quality of cacao drying. (C) 2010 Elsevier Ltd. All rights reserved.