2 BULLETIN 666, U. S. DEPARTMENT OF AGRICULTURE. 
it to ferment and then stopping the fermentation by heat; or simply ’ | 
adding water to the cocoa and heating the product to drive off this | 
added water, have all been employed. When alkalies are used, the | 
cocoa beans are partly roasted, then cracked, and the shells removed. — 
The nibs are then treated, either in the roaster or in a separate 
kettle, with the salt dissolved in water, or, in the case of magnesium 
carbonate, made into an emulsion with water. The roast is then 
finished, heat being applied gradually to drive off the water com- | 
pletely. Sometimes this procedure is varied by roasting the beans | 
entirely and cracking and winnowing them, adding the chemical 
to the cracked nibs in a water-jacketed kettle and applying heat until | 
the product is dry. Although the first occasion for the employment 
of any of these methods was undoubtedly an attempt to develop a 
darker color in cocoas, it was later claimed that the alkali treatment — 
renders the cocoa more soluble in water. There is practically no | 
doubt that any of these treatments produces a cocoa which forms 
a more perfect suspension in the cup and which does not separate 
as readily from the water solution as does an untreated cocoa. This © 
is largely due to the fact that a portion of the starch is gelatinized | 
by the action of the water in the treatment of the cocoa. It is also © 
claimed that the alkali disintegrates some of the cell walls, and in this | 
way enables the cocoa to stand up better in the cup. | 
This investigation was undertaken primarily with a view to ascer- — 
tainmg whether the alkali treatment does in fact render the cocoa 
more soluble, and what changes take place in the cocoa as a result | 
of this treatment. Comparatively little work has been done on the — 
subject of alkali-treated or ‘‘Dutched’’ cocoas, and practically |) 
none with the object of the investigation here reported. . | 
Farnstemer + has made an exhaustive study of the effect on the 
cocoa ash of the addition of varying amounts of potassium carbonate — 
and magnesium carbonate to cocoa. His work was carried out by | 
treating the raw cocoa bean, which had been shelled and ground as 
finely as possible, with a definite amount of these reagents, ashing 
the mixture, and determining the ash constants on this product. 
In addition to this, he has worked out formulas for the determination 
of the amount of alkali used. He also examined a large number of | 
cocoas in the same way, and endeavored from his researches to 
determine the percentage and kind of alkali employed. Other refer- | 
ences to treated cocoas may be found in ‘‘Cocoa and Chocolate.”’? | 
Practically the only subjects treated of in this book are the ash 
constants and the method of manufacture of Dutch process cocoa. 
1Z. Nahr. Genussm. (1908) 16: 625-645. 
2°;Whymper. P, Blakiston’s Son & Co, (1912): 103-110, 117, 231-238, 
