Theobroma cacao L., "The food of the Gods": quality determinants of commercial cocoa beans, with particular reference to the impact of fermentation.

The quality of commercial cocoa beans, the principal raw material for chocolate production, relies on the combination of factors that include the type of planting material, the agricultural practices, and the post-harvest processing. Among these, the fermentation of the cocoa beans is still the most relevant since it is the process whereby the precursors of the cocoa flavor arise. The formation of these precursors depends on the activity of different microbial groups on the beans pulp. A comparison of fermentations in different countries showed that a well-defined microbial succession does not always take place and that the role of Bacillus spp. in this process remains unclear. Considering the overriding importance of the fermentation to achieve high quality commercial cocoa beans, we discuss the need of addressing the impact of the farming system, the ripeness state of the pods, and the role of microbial interactions on the fermentation in future research. In addition, the problem of high acidification cocoa beans, aspects dealing with the volatile fraction of the flavor, and the cocoa butter properties, all were identified as critical aspects that need further investigation. The standardization of the microbiological methods and the application of metagenomic approaches would magnify the knowledge in this domain.