940 FOODS AND FOOD ADULTERANTS. 
The results of Stutzer’s own investigations, referred to above,! were 
obtained with three samples of cocoa powder, and are given as follows: 
Angee q Sample | Sample | Sample 
Of the total nitrogen present, there was found— Noni Novo a Nae 
a ; ; Per cent.| Per cent.| Per cent. 
Nitrogen in form of soluble nitrogenous compounds, | 
includin's; theobpLominess === pe eeb eee scene] eee eee 
Nitrogen in the form of digestible albumen .-.-.-.--.----- 33. 34 40. 61 22. 62 
Nitrogen in the form of indigestible substances. - --------- | 35. 33 32. 44 47. 83 
100, 00 | 160. 00 100. 00 
For quantitative data concerning the nitrogenous constituents, see 
tables on page 960 et seq. 
Starch.—Cocoa contains 5.78 per cent to 15.13 per cent of starch. 
(See tables of analyses.) A more detailed description of this starch will 
be found in paragraphs devoted to the microscopy of cocoa. 
Cocoa red, the coloring matter of the bean, seems to be related to the 
tannins, but authorities differ as to whether it is a decomposition pro- 
duct of a tannin, or whether a tannin is the result of its decomposition. 
It is obtained from the aqueous or alcoholic decoction by precipita- 
tion with lead acetate and decomposition of the washed precipitate 
with hydrogen sulphide. The solution thus prepared has a bitter 
taste; according to Watts, gives a dark green or brown precipitate with 
ferric and a green or sometimes violet precipitate with ferrous salts; 
absorbs oxygen, becoming acid, the coloring matter being converted 
into a kind of tannic acid, which is precipitated by gelatin—cocoa red 
in its unaltered state not being thus thrown down (Hassall).? 
It is colored blue by iron salts and dissolved out by caustie potash 
with a green color, by sulphuric acid with a red color, and by acetic 
acid and aleohol with a violet color. Cold water dissolves the pigment 
with difficulty, while warm water dissolves it entirely. Since the fresh 
seeds are colorless, Mitscherhch presumes that cocoa red is formed by 
a process of oxidation from a body related to the tannins (Moeller).* 
It is changed to tannin by oxidation and colored green by iron salts 
(Tuchen).* 
Concerning the astringent principle of cocoa and cocoa red, Thorpe?’ 
writes as follows: 
The astringent principle is of the nature of tannin, but is different from the tan- 
nin of tea and coffee. It rapidly changes during analysis to cocoa-red, which ren- 
ders its quantitative estimation difficult. It is precipitated by subacetate of lead 
and may be obtained from this precipitate by decomposition with hydrogen sulphide; 
‘Rep. f. anal. chem., 1882, 88 and 165; Hygiene-Bericht, 1882-’83, 1, 217; also op. cit., 
note 8, p. 938 of this work. 
2Hassall, Food: its Adulteration and the Methods for their Detection. 
3Moeller, Mikroskopie der Nahrungs- und Genussmittel aus dem Pflanzenreiche. 
4Tuchen, Dissertation iiber d. organ. Bestandtheile der Cacao, 
6Thorpe, Dictionary of Applied Chemistry. 
