YII FERMENTATION AND DRYING 209 



distilling fermented cocoa by means of vapour of water. 

 Very little is obtained, perhaps only 1 cubic centimetre 

 of essential oil from about 20 kilograms of seeds ; but 

 the smell is so strong that this small quantity is enough 

 to give to the whole mass of cocoa its peculiar aroma. 



Another important substance, theobromine, also 

 appears during fermentation. Like the "cocoa-red" 

 and the essential oil, it is a product of the action upon 

 each other of the different substances which the seed 

 contains and which come into contact as soon as the 

 seed has been killed. 



Finally, the substance which gives the bitter taste 

 to the fresh seeds is partially changed into a tasteless 

 product during fermentation. The bitter-tasting pro- 

 duct in the fresh seeds used to be generally regarded as 

 a tannin, but this also has been proved l to be wrong. 

 It has been given the name " cacaool," and during 

 fermentation it combines with oxygen to form a yellow 

 or reddish-coloured tasteless compound. 



The oxygen of the air is thus necessary for all the 

 processes of fermentation. On the other hand, however, 

 when the beans are fermented longer than is necessary, 

 oxidation sets in too strongly, and brown spots appear 

 on those beans which are .most exposed to the air and 

 which are at the same time subjected to a high tempera- 

 ture. The appearance of these spots is therefore an 

 indication to the planter that fermentation must be 

 stopped. 



The processes of fermentation are not yet thoroughly 

 understood, but it seems that the external fermenta- 

 tion (the fermentation of the pulp) is important only 

 by reason of its production of heat which kills the 

 seeds, with the result that the various substances con- 

 tained in them act upon each other, some of them 

 becoming oxidised. At the same time, the high tempera- 

 ture assists and accelerates these reactions. These 

 changes take place much more easily in the varieties 



1 Ultee and van Dorssen, "Over de zoogenaamde looistof der cacao" 

 (Cultuurg-ids, 1909, 2e. gedeelte, Afl. 12). 



P 



