IN-VITRO STUDIES ON THE PROTEOLYTIC FORMATION OF THE CHARACTERISTIC AROMA PRECURSORS OF FERMENTED COCOA SEEDS - THE SIGNIFICANCE OF ENDOPROTEASE SPECIFICITY

The proteolytic formation of the cocoa-specific aroma precursors was s tudied in vitro using the vicilin-class globulin from cocoa seeds as p rotein substrate and different proteases. Cocoa-specific aroma precurs ors were obtained by degradation of the cocoa globulin with the aspart ic endoprotease from cocoa seeds followed by post-treatment with carbo xypeptidase A from porcine pancreas. Proteolysis products derived from the cocoa globulin by successive digestion with pepsin and carboxypep tidase A also revealed a typical, but less pronounced cocoa aroma upon roasting in the presence of reducing sugars. No cocoa-specific aroma precursors were, however, generated by degradation of the cocoa globul in with chymotrypsin and carboxypeptidase A. Therefore, the specific m ixture of oligopeptides and hydrophobic free amino acids required for the formation of the typical cocoa aroma components is not only determ ined by the structure of the protein substrate but also dependent on t he specificity of the endoprotease.