Volatile Compounds and Flavor Substances

The odorants of cocoa powder are listed in Table 21.24. A model (cf. 5.2.7) made by using the 24 aroma substances on the basis of deodorized cocoa powder reproduced the aroma of cocoa very closely. 

The taste of cocoa is described by the attributes bitter, astringent and sour. It can be reproduced by mixing 41 constituents dissolved in water (pH 5.5). The key compounds for the individual notes are the substances listed in Table 21.23. Apart from theobromine, a series of diketopiperazines are involved in the bitter taste (cf. Table 21.23), which are formed during the thermal degradation of proteins during roasting (Formula 21.10)  

The intensity of the bitter taste of theobromine is increased by the interaction with certain diketopiperazines, a molar ratio of 2 1 giving the highest intensity. However, only those complexes are synergistically active in which the hydrogen bridges shown in Formula 21.11 can be formed. Thus, synergism does not occur when, e. g., in caffeine, the N(l)-atom in the purine ring is methylated. 

Apart from the compounds mentioned in Table 21.23, epicatechin contributes to the astringent taste and also influences the bitter note. 

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