In addition to the volatile oil, which is contained in roasted coffee in the proportion of about 1 part in 50,000, coffee contains caffeine, of which there is ¾ to 1 per cent., and an astringent acid, called caffeo-tannic or caffeic acid, which differs from ordinary tannin in that it does not blacken a solution of an iron salt.
The chief adulteration of coffee is Chicory, which is thought by some to improve the coffee. It is generally harmless, though in some people it produces heartburn and diarrhœa. Chicory is prepared from the root of the wild endive. It contains a volatile oil and a bitter principle, but no caffeine. It is, therefore, of no utility as a stimulant. Its presence can be detected by shaking a little of the suspected coffee on to the surface of the water in a wine-glassful of cold water. Coffee swims on the surface, and gives little or no colouration to the water; while chicory sinks, and gives a deep red tint. The aqueous extract of pure coffee (extracted by boiling water) is, when evaporated, 25 to 30 per cent. of the weight of the original decoction of coffee; while that of chicory is 65 to 70 per cent.; and on this basis, as well as on the fact that a filtered decoction of 10 grammes of coffee in 100 c.c. of distilled water, cooled to 60° F. has a specific gravity of 1009, while that of a similar solution of chicory would be 1021, the proportion of chicory in a mixture of coffee and chicory can be calculated. The microscopical appearances of the two powders differ, coffee showing hexagonal cells and no laticiferous vessels, unlike chicory. There is no law against selling mixed coffee and chicory, if the fact that it is a mixture is stated; and the proportion of the two unfortunately is not required to be stated. As a pound of coffee costs five times as much as a pound of chicory, it is obviously to the purchaser’s advantage to make his own mixture in the proportions desired.
The Preparation of Coffee ought to be effected as in the case of tea—by making an infusion and not a decoction, i.e. by pouring boiling water on the coffee and allowing it to stand, but not continuing the boiling. Continuance of boiling dissipates the delicate aroma.
Inasmuch as coffee contains a much smaller percentage of theine than tea, more of the former must be used to obtain a beverage equally refreshing with tea. Two ounces to a pint of boiling water are required. The infusion thus made should be mixed with an equal part of boiled milk. The coffee ought, if possible, to be freshly roasted.
The colour of coffee is no guide to its strength. Many of the black coffees, especially “French coffee,” owe their colour to the caramel (burnt sugar) contained in the chicory mixed with them.
Coffee has similar properties to tea, with some minor differences. (1) Like tea, it is restorative and sustaining in its action, but seems to act more quickly than tea. (2) Unlike tea, it does not tend to produce perspiration, but rather a dry hot skin. (3) With some it is decidedly laxative; while tea, especially if badly made, has an opposite effect; but this is not always true. (4) It seems to have a greater power of antagonising the effects of alcohol than tea; and is a valuable antidote, after the action of an emetic, in poisoning by opium or arsenic or alcohol.
As a rule, coffee is not so prone to disorder the digestion as tea, but this is not universally true, and in some persons it always produces “biliousness.” When taken in excess, it produces—besides indigestion—palpitation, restlessness, irritability, sleeplessness, and a condition of general nervous prostration; in fact, similar symptoms to those produced by a prolonged over-indulgence in tea.
While the consumption of tea is rapidly on the increase, that of coffee is steadily diminishing. This is partly owing to the greater expense of coffee—a larger quantity being required to form a good beverage; and partly to the greater difficulty in preparing good coffee.
COCOA.
Cocoa, or more properly cacao, is obtained from the seeds of the Theobroma Cacao—a native of the West Indies, Mexico, and the central parts of America. Its name Theobroma was given it by Linnæus, and means the “food of gods.” The fruit is a large leathery capsule, having nearly the form of a cucumber. It contains from 25 to 30 seeds, each about the size of an almond. Before using, these are roasted like coffee berries, and a peculiar aroma is developed in this process as in the case of coffee. The beans or seeds are then manufactured into three different products. (1) They are simply deprived of their husks and broken to pieces; this forms Cocoa-Nibs. (2) They are ground, husk and all, between hot rollers into a paste, and mixed with starch and sugar; this forms Cocoa. (3) They are shelled and then ground into a paste, as in making cocoa; sugar and some seasoning, usually vanilla, being subsequently thoroughly mixed; this paste is Chocolate.