The precursors of chocolate aroma were concentrated, in a fraction amounting to some 5% of the fermented shell-free cocoa bean, by solvent extraction and dialysis.The concentrate, which was soluble in both methanol and water, comprised sugars, amino acids, and flavonoids, and produced chocolate aroma when heated.Examination of unfermented cocoa bean revealed significant differences in these components prior to fermentation.

Eleven members of the homologous series of paradols, of which one, [6] paradol (n-heptyl 4-hydroxy-3-rnethoxyphenethyl ketone), occurs naturally in the seeds of Amomum melegueta Roscoe (Zingiberaceae) (otherwise known as Grains of Paradise, Guinea pepper, or Melegueta pepper), have been synthesised by an improved method. Physical characteristics, including g.1.c. behaviour, and pungency evaluation experiments are described for the series.THE paradols 1 ~2 are a series of phenolic ketones of general formula (1), structurally related to the gingerols (2) and the shogaols (6).3 Representatives of all three types of molecule have been identified l s 3 as pungent principles in the oleoresin of commercial extracts of ginger, prepared from the rhizomes of the tropical plant Ziizgiber oflcinale Roscoe (Zingiberaceae) ; [6]gingerol (3) and [6]paradol (13) have been found in the seeds of Amomum melegueta Roscoe (Zingiberaceae) , variously known as Grains of Paradise, Guinea pepper, or Melegueta pepper .4t The number bracketed before the name designates the number of carbon atoms in the aldehyde which would be produced by a retro-aldol reaction on the gingerol (2). Thus each gingerol (2) is identified by the length of this potentially aldehydic portion of the side chain. To ensure consistency, the same nomenclature has been adopted to cover the shogaols (6) and the paradols ( l ) , though it is recognised that the latter cannot undergo retro-aldol fission.$ B. P. Appl. 45379/1972.

SUMMARY— Amino acids are produced during the fermentation of cocoa beans at a rate which is in agreement with the already established rapid rate of flavour and aroma development. The role of these compounds as aroma precursors receives further confirmation as a result of these studies, and an objective method of assessing the “degree of fermentation” of cocoa beans has been described and tested on a number of different commercial varieties of cocoa.

SUMMARY— The sucrose in fresh cocoa beans is hydrolyzed to glucose and fructose during fermentation and the rate of the reaction confirms the possible inclusion of reducing sugars among the precursors of chocolate aroma. The optimal concentration of reducing sugars in the bean is reached at about the same time as maximal flavor development, and coincides approximately with the peak in amino acid concentration. An objective method for assessing the “Degree of Fermentation” of cocoa beans has been proposed and tested.

SUMMARY The destruction of reducing sugars during the roasting of cocoa beans was investigated and found to be almost complete. The significance of this observation is discussed in relation to the possible role played by the reducing sugars in the deamination of the free amino acids of the cocoa bean, and to flavor development.