Food Adulteration and Its Detection. Jesse P. Battershall
at 15°·5, of various infusions made in this manner:—
| Acorns | 1·0073 |
| Peas | 1·0073 |
| Mocha coffee | 1·0080 |
| Beans | 1·0084 |
| Java coffee | 1·0087 |
| Jamaica coffee | 1·0087 |
| Costa Rica coffee | 1·0090 |
| Ceylon coffee | 1·0090 |
| Brown malt | 1·0109 |
| Parsnips | 1·0143 |
| Carrots | 1·0171 |
| Yorkshire chicory | 1·0191 |
| Black malt | 1·0212 |
| Turnips | 1·0214 |
| Rye meal | 1·0216 |
| English chicory | 1·0217 |
| Dandelion root | 1·0219 |
| Red beet | 1·0221 |
| Foreign chicory | 1·0226 |
| Mangold wurzel | 1·0235 |
| Maize | 1·0253 |
| Bread raspings | 1·0263 |
Assuming the gravity of the pure coffee infusion to be 1·0086, and that of chicory to be 1·0206, the approximate percentage of coffee, C, in a mixture, can be obtained by means of the following equation, in which D represents the density of the infusion:—
C = 1·00(1·020 - D) 12.
This was tested by mixing equal parts of coffee and chicory, and taking the specific gravity of the infusion; it was 1·01408, indicating the presence of 49 per cent. of coffee. Some idea of the amount of foreign admixture (especially chicory) in ground roasted coffee may be formed from the tinctorial power of the sample. It has already been mentioned that coffee imparts much less colour to water than do most roasted grains and roots. The table below shows the weights of various roasted substances which must be dissolved in 2·000 parts of water in order to produce an equal degree of colour:[11]—
| Caramel | 1·00 |
| Mangold wurzel | 1·66 |
| Black malt | 1·82 |
| White turnips | 2·00 |
| Carrots | 2·00 |
| Chicory (darkest Yorkshire) | 2·22 |
| Parsnips | 2·50 |
| Maize | 2·86 |
| Rye | 2·86 |
| Dandelion root | 3·33 |
| Red beet | 3·33 |
| Bread raspings | 3·36 |
| Acorns | 5·00 |
| Over-roasted coffee | 5·46 |
| Highly-roasted coffee | 5·77 |
| Medium-roasted coffee | 6·95 |
| Peas | 13·33 |
| Beans | 13·33 |
| Spent tan | 33·00 |
| Brown malt | 40·00 |
The comparative colour test may also be applied as follows:[12]—One gramme each of the sample under examination, and of a sample prepared by mixing equal parts of pure coffee and chicory, are completely exhausted with water, and the infusions made up to 100 c.c. or more; 50 c.c. of the filtered extract from the suspected sample are then placed in a Nessler cylinder, and it is determined by trial how many c.c. of the extract from the standard mixture, together with enough distilled water to make up the 50 c.c., will produce the same colour. In calculating the chicory present, it is assumed that this substance possesses three times the tinctorial power of coffee.
(b) Chemical Examination.—Some of the chemical properties of roasted coffee afford fairly reliable means for the detection of an admixture of chicory. Coffee ash dissolves in water to the extent of about 80 per cent.; of the ash of roasted chicory only about 35 per cent. is soluble. Coffee ash is almost free from silica and sand, which substances form a notable proportion of the constituents of the ash of chicory.
The following (see p. 36) are the results obtained by the writer from the analysis of the ash of coffee and chicory.
It will be observed from these analyses, that the most distinctive features presented by coffee ash are the absence of soda, and the small amounts of chlorine, ferric oxide and silica present. In these respects, it is very different from the ash of chicory. The proportion of phosphoric acid found in the latter is in excess of that given by some authorities. Several analyses of chicory ash have been made by the author, and, in every instance, the amount of phosphoric acid was over 8 per cent.; in one sample of the ash of commercial chicory it approximated 13 per cent.
| Java Coffee. | Chicory Root | |
| per cent. | per cent. | |
| Percentage of ash | 3·93 | 4·41 |
| Potassa | 53·37 | 23·00 |
| Soda | .. | 13·13 |
| Lime | 5·84 | 9·40 |
| Magnesia | 9·09 | 5·88 |
| Alumina | 0·43 | .. |
| Ferric oxide | 0·53 | 5·00 |
| Sulphuric acid | 3·19 | 9·75 |
| Chlorine | 0·78 | 4·93 |
| Carbonic acid |
|