Application of an aroma extract dilution analysis in parallel applied to the volatiles isolated from a sample of fermented cocoa with a pronounced smoky off-flavor and a reference sample with flawless aroma revealed seven potential off-flavor compounds with smoky/phenolic odor qualities and higher flavor dilution factors in the off-flavor sample than in the reference sample. These compounds were 2-methoxyphenol, 3- and 4-methylphenol, 3- and 4-ethylphenol, and 3- and 4-propylphenol. Their quantitation in seven off-flavor samples and two reference samples without off-flavor showed that 4-propylphenol did not exceed its odor threshold value. From the concentrations obtained for the other six compounds and their odor threshold values in deodorized cocoa butter, maximum tolerable concentrations were derived for the incoming goods inspection in the chocolate industry. The suggested limits are 2 μg/kg for 3-ethylphenol and 3-propylphenol, 20 μg/kg for 4-methylphenol, 3-methylphenol, and 4-ethylphenol, and 70 μg/kg for 2-methoxyphenol.
Keywords: 2-methoxyphenol; 3-ethylphenol; 3-propylphenol; 4-methylphenol; Theobroma cacao; aroma extract dilution analysis; stable isotopically substituted odorants.