a 
rites 
* 
i 
EFFECT OF ALKALI TREATMENT ON COCOAS. 9 
alkalinity shows a maximum for the treated cocoas of 8.10 cc above 
the maximum for the untreated cocoas, and an average of 3.16 cc 
higher. ‘There is very little difference in the figures on the insoluble 
alkalinities, and this difference would be still slighter if it were not 
for those few samples which have been treated with magnesium 
carbonate and which show a higher water-insoluble alkalinity on 
that account. 
WATER-SOLUBLE MATTER IN UNTREATED AND TREATED COCOAS. 
In order to determine the effect of alkali treatment on the solu- 
bility of the cocoa, the total water-soluble matter was determined in 
both treated and untreated cocoas. This was done.by rubbing up 
10 grams of the cocoa with, 250 cc of water, heating to boiling and 
boiling for a minute, then allowing to stand over night and filtering. 
Fifty ce of this filtrate, corresponding to 2 grams, of the original 
cocoa, were evaporated to dryness and dried to constant weight. 
Thesesolids were then ashed, and the total ash, water-soluble ash, water- 
insoluble ash, alkalinity of the soluble ash, and alkalinity of the insolu- 
ble ash determined on each sample. Nitrogen was determined on a 50 
ce portion of the filtrate, and protein calculated from this determin- 
ation. Itwasnoted that on addition of acid to the watersolution of the 
‘‘Dutched”’ cocoas a flocculent precipitate was thrown down. Upon 
investigation this proved to be a nitrogenous substance. Todetermine 
the amount of this nitrogenous substance present, a measured portion 
of the water solution of the cocoa was made acid with 1 per cent of 
sulphuric acid. This was then filtered, and nitrogen was determined 
upon an aliquot of the filtrate, and the protein calculated therefrom. 
The difference between the protein as here determined and that of 
the total water-soluble protein was the nitrogenous substances pre- 
cipitated by the sulphuric acid. The color value on a brewer’s scale 
of the water solution was determined in a Lovibond tintometer, using 
a -inch cell. In making the water solution the cocoa was weighed 
as it came, but the results were all calculated to a moisture- and fat- 
free basis. These results are listed in Tables 5, 6, and 7. Table 5 
Ve gives the results obtained on untreated cocoas, Table 6 those on cocoas 
treated with alkalies, and Table 7 the comparison of the same blend 
of beans treated in various ways. 
The water-soluble matter in the untreated cocoas varies from 29.16 
to 35.55 per cent, with an average of 31.58 per cent. In the alkali- 
treated cocoas it varies from 24.90 to 37.02 per cent, with an average 
_ of 32.16 per cent. The minimum was obtained on a sample which 
_ was treated with magnesium carbonate, the next lowest being 28.17 
per cent. The maximum percentage of water-soluble material in the 
alkali-treated cocoas is higher than that in the untreated cocoas by 
1.47, while the average is 0.58 higher. This increase in solu- 
45789°—18—Bull. 666-2 
