Already the Assam teas are held in high estimation by good judges of tea in this country, whilst they fetch a high price in India for local consumption.
The colour of the berry is by no means a decisive criterion of excellence of quality; in some parts the bluish berry is esteemed most highly, in others the yellow. The West Indian coffees often change colour when kept a few years.
It is well known that the various sorts of coffee imported into Europe from the several parts where the plant is cultivated differ widely in quality and flavour. Levantine or Mocha still retains its old superiority in this respect, though the best sorts imported from Ceylon, Bourbon, Mauritius, and other Indian Islands are now generally considered to come very near it. This difference in quality and flavour of the various sorts of coffee is generally attributed to climatic and local causes and influences, which are necessarily beyond the power of remedy. This, however, is a great mistake. The more or less advanced state of maturity to which the berry is allowed to attain before picking, and, more particularly still, the degree of dryness, and the longer or shorter period of time for which it is kept before being sent into the market, exercise a most powerful influence upon the quality and flavour of the article. Berries gathered before they have attained maturity, though they may be perfect in colour, will always have a raw, herbaceous taste. If the drying berries are heaped too thickly or closely, they are apt to heat and to contract an unpleasantly bitter and harsh taste, and a disagreeable smell; this will frequently occur also where artificial heat is had recourse to expedite the drying. Keeping tends to cure these serious defects in coffee. There are instances on record where coffee of a most disagreeable flavour and smell has been brought near perfection by being kept for some years in a dry loft; and though it may be going too far to assert, as has been done by some high authorities on the subject, that “the worst coffee produced in the West Indies will, in a course of years not exceeding ten or fourteen, be as good, parch and mix as well, and have as high a flavour as the best we have now from Turkey,” still there can be no doubt that long keeping will most materially improve the quality of even the worst sorts. Unfortunately, the difference of price between inferior and superior coffee is not sufficiently great to cover so many years’ interest on the capital invested. It is for the same reason that planters, though they are perfectly aware that trees growing on a light soil, and in dry and elevated spots, produce smaller berries of very superior flavour to those grown in rich, flat, and moist soils, yet prefer cultivating the latter, simply because the production is double that of the better sort. Those who wish to improve the quality of their coffees by keeping, must bear in mind that perfect dryness of the loft or warehouse, moderate warmth, and gentle ventilation are the indispensable conditions of success; a strong draught of air is more particularly to be guarded against, as it tends to bleach the berries. Great care must be taken, also, to keep all strong-flavoured wares, such as pepper, pimento, ginger, cod-fish, herrings, rum, &c., as far as possible from the coffee, which has a powerful attraction for these scents, and gets thoroughly impregnated with them, to the great deterioration, of course, of its quality. This remark applies more particularly to the shipping of coffee from Jamaica and the other West India Islands. Want of proper ventilation in the holds in which a cargo of coffee is stowed on board ship, is equally injurious to the quality of the article. Coffee which has suffered damage by sea-water, or has been spoiled by the close vicinity of strong-scented wares, may, to some extent, be reclaimed by “rouncing” or putting it in a tub, pouring boiling water over it, stirring for a few minutes, then pouring the water off, repeating the same operation a second, or even a third time, if necessary, and most carefully drying the washed berries.
SECTION V.
CHEMICAL ANALYSIS.
Coffee has been analysed by several chemists, and though the results obtained differ in some slight degree, yet it seems pretty clear that the principal constituents to which its hygienic and medicinal properties are due are caffeine, a peculiar volatile oil generated in the roasting, and a kind of tannic acid.
The alkaloid caffeine, or theine, is found in one or two other plants besides tea and coffee. It occurs in the seeds of Paullinia sorbilis, a native of Brazil, and in the leaves of several species of holly, natives of South America, which furnish the Paraguay tea, or Yerba mate, so large an article of consumption in several of the South American republics. The leaves and young shoots, dried, parched, and pulverised, are used for a hot infusion. A kind of cake, called Guarana bread, is made from the seeds of the Paullinia, which is highly esteemed in Brazil and other countries when infused, like chocolate, for its nutritive and febrifuge properties, and is sold generally as a necessary for travellers, and as a cure for many diseases.
The nutritive and medicinal virtues of all these plants must certainly be attributed in a great degree to the presence of this chemical principle, and to the tannic acid which they also contain.
The use of coffee as a beverage has been examined in a chemical and physiological point of view by Professor Lehmann. The general results of his investigations are:
1. That a decoction of coffee exercises two principal actions upon the organism, which are very diverse in character, viz. increasing the activity of the vascular and nervous system, while at the same time it retards the metamorphosis of plastic constituents.
2. That the influence of coffee upon the vascular and nervous system, its reinvigorating action, and the production of a general sense of cheerfulness and animation, is attributable solely to the mutual modification of the specific action of the empyreumatic oil and the caffeine contained in it.