Indicator Compounds and Precursors for Cocoa Aroma Formation

During cocoa roasting several hundred volatile aroma compounds are formed. Therefore we looked for compounds that would indicate the degree of roasting. It turned out, that within the range of technical roasting processes, the concentration of 2,3-dihydro-3-hydroxymaltol has a linear correlation with respect to the extent of roasting, and the concentration of dimethylpyrazines strongly increases at the beginning of overroasting. Amadori compounds formed by reaction of aldoses and amino acids are aroma precursors. Their concentrations increase during pre-drying prior to roasting. In model roasting experiments with fructosealanine, a typical aroma precursor detected in cocoa, different classes of aroma compounds (pyrazines, pyrroles, pyridines, furans), which have already been described for the aroma of cocoa, were formed. Their formation depends on reaction conditions.