Fermented cocoa is occasionally affected by off-flavors, which might be transferred into the final product and then lead to rejection by the consumers. The occurrence of moldy, smoky, fecal, mushroom-like, and coconut-like off-flavors has been reported. Among them, the smoky off-flavor, often also referred to as hammy off-flavor, is the most prevalent.<br/>For the elucidation of the molecular background of smoky off-flavors, a fermented cocoa sample showing a pronounced off-note was subjected to gas chromatography–olfactometry (GC–O) and aroma extract dilution analysis (AEDA). A fermented cocoa sample with a flawless and typical aroma was used as a reference and analyzed in parallel. The comparative AEDA in combination with the structure elucidation of major odorants revealed the following potential off-flavor compounds (flavor dilution (FD) factor in the off-flavor sample/FD factor in the reference sample): 4-ethylphenol (4096/&lt;1), 2-methoxyphenol (2048/512), 3- and 4-propylphenol (2048/&lt;1), 3-methylphenol (256/&lt;1), 4-methylphenol (64/&lt;1), and 3-ethylphenol (16/2). To estimate the contribution of the individual odorants to the observed off-flavor, their concentrations were determined in various smoky off-flavor samples as well as in flawless reference samples by using stable isotopically substituted odorants as internal standards. Data were related to the individual breakthrough thresholds of the potential off-flavor compounds determined in deodorized cocoa butter, cocoa liquor, and chocolate mass. Results showed that particularly 4-ethylphenol, 4-methylphenol, 3-methylphenol, and 3-ethylphenol contributed to the observed smoky/hammy off-flavor. Further studies will focus on the identification of the crucial processing parameters promoting the formation of these compounds. This will finally lead to suggestions on how to avoid their formation on the way from the cocoa pods to fermented cocoa.

Elucidation of the molecular background of smoky and hammy off-flavors in cocoa

2019 Fall National Meeting

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