THE PROTEOLYTIC FORMATION OF ESSENTIAL COCOA-SPECIFIC AROMA PRECURSORS DEPENDS ON PARTICULAR CHEMICAL STRUCTURES OF THE VICILIN-CLASS GLOBULIN OF THE COCOA SEEDS LACKING IN THE GLOBULAR STORAGE PROTEINS OF COCONUTS, HAZELNUTS AND SUNFLOWER SEEDS
J. Voigt et al., THE PROTEOLYTIC FORMATION OF ESSENTIAL COCOA-SPECIFIC AROMA PRECURSORS DEPENDS ON PARTICULAR CHEMICAL STRUCTURES OF THE VICILIN-CLASS GLOBULIN OF THE COCOA SEEDS LACKING IN THE GLOBULAR STORAGE PROTEINS OF COCONUTS, HAZELNUTS AND SUNFLOWER SEEDS, Food chemistry, 51(2), 1994, pp. 197-205
Cocoa-specific aroma precursors were generated in vitro, when the vici
lin-class globulin of cocoa seeds was successively degraded by the asp
artic endoprotease and the carboxypeptidase isolated from ungerminated
cocoa seeds. To study the significance of the chemical structure of t
he protein substrate, globular storage proteins were isolated from dif
ferent crops and subjected to proteolysis by the aspartic endoprotease
and the carboxypeptidase of ungerminated cocoa seeds. The obtained pr
oteolysis products were comparatively analysed for their patterns of o
ligopeptides and free amino acids and were roasted in the presence of
reducing sugars and deodorised cocoa butter. Sensory evaluation of the
roasting aromas revealed that neither the proteolysis products of the
legumin-class globulins from hazelnuts or sunflower seeds, nor those
derived from the vicilin-class globulin of coconuts contained the typi
cal pattern of aroma precursors formed by degradation of the vicilin-c
lass globulin of cocoa seeds with the same proteases. Considerable dif
ferences were observed between the patterns of free amino acids and ol
igopeptides generated by proteolysis of the cocoa vicilin and of the g
lobular storage proteins from the other crops. These findings indicate
that the formation of the cocoa-specific aroma precursors is determin
ed by the particular chemical structure of the vicilin-class globulin
present in the cocoa seeds.