Molecular Sensory Analysis Confirms Wood Smoke Exposure as a Source of Smoky Off-Flavors in Fermented Cocoa

Among the off-flavors occasionally found in fermented cocoa, a smoky taint is common. While major contributors to the off-flavor are already known, their source has not been fully clarified: wood smoke contact during drying and overfermentation are currently discussed. Odorant screening by gas chromatography-olfactometry and aroma extract dilution analysis applied to a cocoa sample smoked in a worst-case scenario confirmed 2-methoxyphenol, 3- and 4-methylphenol, 3- and 4-ethylphenol, and 3-propylphenol as important smoky odorants and additionally suggested 2,6-dimethoxyphenol as a potential off-flavor compound. Quantitation and odor activity value calculation of the compounds in fermented cocoa with authentic wood smoke contact in the origin revealed 2-methoxyphenol, 4-methylphenol, and 3-ethylphenol as the most potent smoky odorants. Their distribution between nibs and husks showed considerable diffusion into the nibs; thus, husk removal during further processing cannot guarantee a substantial reduction of the smoky compounds.