Coffee and chicory

SECTION III.

STRUCTURE AND CHEMICAL COMPOSITION.

Three persons partook of a chicory breakfast. The infusion was dark-coloured, thick, destitute of the agreeable and refreshing aroma so characteristic of coffee, and was of a bitter taste.

Each individual experienced for some time after drinking this infusion a sensation of heaviness, drowsiness, a feeling of weight at the stomach, and great indisposition to exertion; in two headache set in, and in the third the bowels were relaxed. In second and third trials of the chicory breakfast the same feelings of drowsiness, weight of the stomach, and want of energy were experienced, but no headache or diarrhœa. Several other trials were subsequently made, with nearly similar results. But chicory, it will be said, is seldom taken alone in this country, and when mixed with coffee these effects are not produced.

Two persons partook, for a considerable period, twice a day, of an article denominated coffee, costing 1s. 6d. a pound, and largely adulterated with chicory; during nearly the whole of this time they both suffered more or less from diarrhœa.

From the results of these trials, therefore, we are warranted in concluding that at least some doubt is attached to the assertion of the wholesome properties of chicory-root as an article of diet.

Several characters, sufficiently simple and easily recognised for general application, have been indicated in different works for detecting the addition of roasted chicory to coffee in the roasted and ground state, but the application of chemical reagents for detecting the presence of the colouring matter of roasted chicory, when added to infusion of coffee, has not yet proved successful.

The brownish-yellow colouring matter which is developed in chicory-root by the process of roasting, when dissolved in water by infusion or decoction, retains its colour, or becomes a little deeper by the action of persalts of iron, without giving rise to any precipitation.

The brown colouring matter of roasted coffee, on the other hand, acquires, from the same reagent, a green colour, and a brownish-green flocculent precipitate is formed. These two different reactions may be applied, not only for distinguishing the pure infusion of coffee and of chicory, but also those which contain a mixture of the soluble principles of the two alimentary substances.

Infusion of pure coffee acquires a green colour, more or less intense, on the addition of some drops of persulphate of iron.

Infusion of pure chicory, under similar circumstances, retains its brownish-yellow colour, which becomes more intense, and acquires a slight greenish tint.

A mixture of the two infusions, containing one-half, a fourth, or a fifth of its volume of infusion of chicory, may be recognised by its brownish-yellow colour, which remains after the deposition of the precipitate produced by the salt of iron, together with part of the colouring matter of the coffee. This separation may be expedited by rendering the coloured liquor slightly alkaline by the addition of a small quantity of weak solution of ammonia, and allowing it to stand in tubes closed at one end. The supernatant liquor, after the precipitate has deposited, will possess a brownish-yellow tint by refracted light, which will be deeper in proportion to the quantity of chicory present.

If the experiment be first made with infusion of pure coffee of a certain strength, and afterwards with additions of known quantities of chicory, keeping these for comparison, the quantity of chicory in a mixed sample may be thus determined.[2]

A simple means of detecting the chicory in ground coffee is as follows:

Throw about a tea-spoonful of the suspected coffee in a wine-glass of water, and stir the mixture with a spoon. If

the coffee be pure, it for the most part floats, becomes very slowly moistened, even when shaken up with the water, and communicates scarcely any colour to the liquid; very gradually it imbibes water; the liquid acquires a very pale sherry tint; and at the end of several hours the greater part of the powder is found to have fallen to the bottom of the glass. If, however, it be chicorised, the presence of chicory (genuine or spurious) will be readily detected, by a portion of the suspected powder rapidly sinking and communicating to the liquid a reddish-brown tint, which will be more or less deep according to the amount of chicory present.

If the coffee be adulterated with what is called Hambro’ powder (roasted and ground peas, &c., coloured with Venetian red) or roasted corn, we have a further test in iodine, which communicates a purplish or bluish-red tint to the water to which either of these substances has been added. The preceding test is sufficiently delicate and valuable, in all ordinary cases, for detecting chicory in coffee; but to those familiar with microscopic investigations, the microscope furnishes another mode of proceeding: fragments of dotted ducts being found in chicory, but not in pure coffee. They are not met with, however, in great abundance; and some patience and care, therefore, are requisite in searching for them. The starch grains of Hambro’ powder are readily detected by the microscope, as also the blackening effect of a solution of iodine on them.

Plate 10 represents the structure and character of genuine ground roasted coffee, and of a fragment of roasted chicory-root, showing the dotted or interrupted spiral vessels which pass in bundles through the central parts of the root, magnified 140 diameters; copied, by permission, from Dr. Hassall’s work on “Food and its Adulterations.”

In the raw chicory-root three parts or structures may be distinguished with facility, cells, dotted vessels, and vessels of the latex. These vessels afford useful means of distinguishing chicory from some other roots employed in the adulteration of coffee. The chief part of the root is made up of little utricles or cells. These are generally of a rounded form, but sometimes they are narrow and elongated. The former occur when the pressure is least and the root soft, the latter in the neighbourhood of the vessels.[3]

There are four characters by which adulterated chicory may be distinguished from the genuine.

1st. It yields to cold water a much whiter colour. In using this test it is necessary to have a sample of genuine chicory for comparison.

2ndly. A decoction of chicory containing either roasted grain or pulse, yields when cold a purplish or bluish-black colour, with a solution of iodine; whereas a corresponding decoction of genuine chicory is merely coloured brown by iodine.

3rdly. The microscope detects in adulterated chicory the torrefied starch grains of either corn or pulse. That they are starch grains is shown by the action of a solution of iodine, which blackens them.

4thly. The odour and flavour will sometimes detect adulterations.

Roasted and ground chicory attracts water from the air, and thereby increases in weight and becomes clammy. The grinders are accustomed to return as much by weight of ground chicory as they receive of the unground root, for the loss which the root suffers by grinding is more than compensated by the absorption of water from the air.

THE END.

C. WHITING, BEAUFORT HOUSE, STRAND.