Off-Flavor Compounds in Fermented Cocoa: Impact of Overfermentation

The compounds responsible for a variety of off-flavors that occasionally occur in fermented cocoa have recently been identified, but their origin is not yet fully understood. However, overfermentation has been suggested as a possible source. Quantitation of potential off-flavor compounds in well fermented and overfermented samples resulting from fermentation trials in Nicaragua and Costa Rica showed that overfermentation can lead to smoky, leathery, and horse stable-like off-flavors caused by 2-methoxyphenol and 4-ethylphenol, and to cheesy, vomit-like off-flavors caused by short-chain carboxylic acids such as 2-methylpropanoic acid, butanoic acid, 2-methylbutanoic acid, and 3-methylbutanoic acid. The concentrations of 2-methoxyphenol and 4-ethylphenol in the overfermented cocoa samples were in a similar range as previously reported in cocoa samples with wood smoke contamination during artificial drying. To avoid overfermentation, measuring the pH of the fermentation mass emerged as a potential alternative to the daily evaluation of a representative number of cocoa bean cross sections.