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 cc of this nitrate, corresponding to 2 grams of the original 

 cocoa, were evaporated to dryness and dried to constant weight. 

 These solids 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 

 cc portion of the nitrate, and protein calculated from this determin- 

 ation. It was noted that on addition of acid to the water solution of the 

 "Dutched" cocoas a flocculent precipitate was thrown down. Upon 

 investigation this proved to be a nitrogenous substance. To determine 

 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. Tins 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 

 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 mi treated 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 mitreated cocoas by 

 1.47, while the average is 0.58 higher. This increase in solu- 

 45789°— 18— Bull. 666 2 



