Cocoa beans, from the fruit of the cocoa tree (Theobroma cacao L.), are transformed into chocolate and other cocoa products by a complex process involving fermentation, drying and roasting. Fermentation is carried out by different methods in the countries of origin, and represents a crucial stage in the development of the aromatic precursors and bioactive compounds characteristic of chocolate and cocoa products. Proteins are the cocoa fraction that undergoes the most intensive modification during fermentation, where microbiological and enzymatic reactions lead to extensive breakdown of cocoa seed proteins, yielding peptides and amino acids which are the important flavour precursors
Peptides and amino acids generated during cocoa bean fermentation are known to be the most important precursors for the development of cocoa aroma. Although cocoa fermentation and aroma development have been extensively studied, the cocoa oligopeptide fraction is under-investigated, so we decided to investigate the presence of oligopeptides in fermented cocoa beans. Peptides were analysed by reversed phase LC/ESI-MS and LC/ESI-MS/MS, and the molecular masses of 44 different peptides were obtained by analysing the mass spectra associated with the most intense chromatographic peaks. Peptides were identified based on the exact molecular masses, mass fragmentation patterns and by comparison with vicilin and 21 kDa cocoa seed protein sequences. Results showed that fermentation strongly influenced the formation of peptides in cocoa beans. Furthermore, peptide patterns of cocoa beans of different origin are variable, suggesting an effect of different fermentation processes. The ratio of peptides generated from vicilin respect to those generated from 21 kDa cocoa albumin seems to be promising as indicator of the fermentation level.
The full manuscript has been recently published in Food Research International
Marseglia, A., Sforza, S., Faccini, A., Bencivenni, M., Palla, G., & Caligiani, A. (2014). Extraction, identification and semi-quantification of oligopeptides in cocoa beans. Food Research International.