Food Adulteration and Its Detection. Jesse P. Battershall
per cent.
Recent analysis of shelled cocoa-beans, made by Boussingault, gave the following results:—
| Fresh. | Dry. | |
| per cent. | per cent. | |
| Fat | 49·9 | 54·0 |
| Starch and starch-sugar | 2·4 | 2·5 |
| Theobromine | 3·3 | 3·6 |
| Asparagine | traces | .. |
| Albumin | 10·9 | 11·8 |
| „gum | 2·4 | 2·5 |
| Tartaric acid | 3·4 | 3·7 |
| Tannin | 0·2 | 0·2 |
| Soluble cellulose | 10·6 | 11·5 |
| Ash | 4·0 | 4·4 |
| Water | 7·6 | .. |
| Undetermined | 5·3 | 5·8 |
Dr. Weigman[15] obtained the following results from an examination of several varieties of the shelled beans:—
| Water. | Fat. | Ash. | Nitrogen. | |
| per cent. | per cent. | per cent. | per cent. | |
| Machala | 4·97 | 47·80 | 3·88 | 2·25 |
| Arriba | 6·57 | 47·44 | 3·52 | 2·31 |
| Caracas | 6·00 | 46·39 | 4·19 | 2·23 |
| Puerto Cabello | 5·71 | 48·74 | 3·94 | 2·13 |
| Surinam | 5·01 | 46·26 | 2·99 | 2·20 |
| Trinidad | 6·07 | 45·74 | 2·04 | 2·04 |
| Port au Prince | 4·73 | 48·58 | 3·89 | 2·33 |
The most important constituents of cocoa are the fat (cocoa-butter), and the alkaloid (theobromine).
Cocoa butter forms a whitish solid of 0·970 specific gravity, fusing at 30°, and soluble in ether and in alcohol.
Theobromine (C7H8N4O2) crystallises in minute rhombic prisms, which are insoluble in benzol, but dissolve readily in boiling water and alcohol. It sublimes at 170°. Theobromine is exceedingly rich in nitrogen, containing over 20 per cent. of the element. In this and many other respects it bears a great resemblance to theine.
The proportion of mineral ash in cocoa varies from 3·06 to 4·5 per cent.
James Bell[16] gives the following composition of the ash of Grenada cocoa nibs:—
| Per cent. | |
| Sodium chloride | 0·57 |
| Soda | 0·57 |
| Potassa | 27·64 |
| Magnesia | 19·81 |
| Lime | 4·53 |
| Alumina | 0·08 |
| Ferric oxide | 0·15 |
| Carbonic acid | 2·92 |
| Sulphuric acid | 4·53 |
| Phosphoric acid | 39·20 |
| 100·00 |
The most characteristic features of the ash of genuine cocoa are its great solubility, the small amounts of chlorine, carbonates, and soda, and the constancy of the proportion of phosphoric acid contained. Bell has also analysed several samples of commercial cocoa. The following will serve to illustrate their general composition:—
| Per cent. | |
| Moisture | 4·95 |
| Fat | 24·94 |
| Starch (added) | 19·19 |
| Sugar (added) | 23·03 |
| Non-fatty cocoa | 27·89 |
| 100·00 |
| Per cent. |