This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Fermented cocoa occasionally exhibits off-flavors that can compromise the quality of chocolate and other cocoa products. But what causes these undesirable flavors?
Researchers at the Leibniz Institute for Food Systems Biology at the Technical University of Munich have now shown that overfermentation of cocoa beans can cause smoky, leathery and cheesy off-flavors. Smoky flavors, therefore, are not necessarily attributable to smoke contamination. It has only been in the past few years that the odorants responsible for many cocoa off-flavors have been identified.
However, how and under what conditions they arise are not yet fully understood. To get to the bottom of the causes, Franziska Krause and principal investigator Martin Steinhaus examined cocoa samples from various stages of fermentation and growing regions. Part of the work took place under real-world conditions on cocoa plantations in Nicaragua and Costa Rica, where Krause monitored the fermentation process onsite.
The study is published in the Journal of Agricultural and Food Chemistry. Using modern odorant analysis techniques in the laboratory, the researchers compared samples of optimally fermented cocoa beans with samples of intentionally overfermented beans. In doing so, they detected elevated concentrations of short-chain carboxylic acids in the overfermented samples.
These compounds can cause off-flavors that smell like cheese, sweat or vomit. The overfermented samples also contained significantly higher concentrations of the compounds 2-methoxyphenol and 4-ethylphenol. Both substances have a smoky odor.
While 2-methoxyphenol has a rather sweet, smoky smell, 4-ethylphenol also exhibits leathery, phenolic and horse stable-like notes. In an earlier study, the research team had already identified and quantified off-flavor compounds typical of wood smoke contamination in cocoa beans. The new results now show that overfermented cocoa beans contain key smoke-like-smelling phenols in concentrations similar to those found in wood smoke–contaminated cocoa.
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