Water 12·000
Woody tissue 34·000
Fixed fatty matters 10 to 13·000
Gum, sugar, and vegetable acids 15·500
Nitrogenous matter allied to
legumin (vegetable casein) 13·000
Free caffein 0·800
Compound of caffein with potash 3.5 to 5·000
Solid fatty essence 0·002
Aromatic essential oil 0·001
Saline matters 6·697
-------
100·000
_Prep., &c._ The finest kind of coffee is that called mocha, from Aden,
but that in common use is principally supplied from the British
plantations in the West Indies. The selection being made, the berries are
carefully roasted in revolving cylinders by a gradually applied heat,
until the aroma is well developed and the toughness destroyed. Too much
heat is avoided, as the volatile and aromatic properties of the coffee,
and, consequently, the flavour, are thereby injured; whilst, on the other
hand, if the berries are roasted too little, they produce a beverage with
a raw, green taste, very liable to induce sickness and vomiting. When
properly roasted, coffee has a lively chocolate-brown colour, and should
not have lost more than 18% of its weight by the process. If the loss
exceeds 20%, the flavour suffers in proportion. The roasted coffee should
be placed in a very dry situation, and excluded from the air as soon as
possible. It loses flavour by keeping, and also powerfully absorbs
moisture from the atmosphere by reason of its hygrometric power.
_Qual., &c._ Coffee promotes digestion, and exhilarates the spirits, and
when strong, generally occasions watchfulness, but in some phlegmatic
constitutions induces sleep. Drunk in moderation, especially if combined
with sugar and milk, it is perhaps the most wholesome beverage known. The
various qualities that have been ascribed to it by some persons such as
dispelling or causing flatulency, removing dizziness of the head,
attenuating the blood, causing biliousness, &c., appear to be wholly
imaginary. In a medical point of view it has been regarded as a cerebral
stimulant and anti-soporific, and as a corrector of opium. As a medicine
it should be strong, and is best taken only lukewarm.
_Adult., &c._ The principal substances used for the purposes of
adulteration are caramel, roasted chicory, roasted locust beans, roasted
corn, &c. Chicory being now charged with the same amount of duty as
coffee, is not considered in a revenue point of view an adulteration;
nevertheless, when we contrast coffee with chicory, we at once see the
vast superiority of the former over the latter, thus:--
Coffee is the fruit of a tree, whilst chicory is the root of an herbaceous
plant, and it is well known that more virtues exist in fruits and seeds
than in roots.
Coffee contains three active principles, viz. an essential oil, caffeia,
and tannic acid, and these exercise a powerful influence on the system,
retarding the waste of the tissues of the body, exciting the brain to
increased activity, and exhilarating without intoxicating. Chicory
contains none of these constituents.
Coffee exerts on the system highly beneficial physiological effects;
chicory possesses medicinal properties, which are not desirable in an
article of food.
Chicory, therefore, is very objectionable, and when a dealer sells a
mixture of coffee and chicory for pure coffee, as is almost invariably the
case, he is guilty of selling an adulterated article, and ought to be
punished accordingly.
The adulteration with caramel or chicory may readily be detected as
follows:--
1. A spoonful of pure coffee placed gently on the surface of a glass of
cold water will float for some time, and scarcely colour the liquid; if it
contains caramel or chicory, it will rapidly absorb the water, and,
sinking to the bottom of the glass, communicate a reddish-brown tint as it
falls. Another method of applying this test is by expertly shaking a
spoonful of the suspected coffee with a wine-glassful of cold water, and
then placing the glass upon the table. If it is pure, it will rise to the
surface, and scarcely colour the liquid; but if caramel or chicory is
present, it will sink to the bottom, and the water will be tinged of a
deep red as before.
2. The brown colour of decoction or infusion of roasted coffee becomes
greenish when treated with a per-salt of iron; and a brownish-green,
flocculent precipitate is formed. The colour of chicory is only deepened,
but not otherwise altered, and no precipitate is formed, under the same
treatment. A mixture of chicory and coffee retains a brownish-yellow
colour after the precipitate has subsided, and the liquid appears brownish
yellow by refracted light. The addition of a little weak ammonia water
aids the subsidence of the precipitate.
[Illustration]
3. Under the microscope (see _Chicory_) the presence of chicory may be
readily detected by the size, form, and ready separation of the cells of
the cellular tissue, and by the presence and abundance of the pitted
tissue or dotted ducts, which are absent from coffee, and by the size of
the spiral vessels, which are very small in coffee. The most
characteristic structure, however, and that by which chicory can be easily
identified, is the lactiferous tissue. Roasted corn, and other amylaceous
substances, may also be detected, in the same way, by the peculiar size
and character of their starch grains.
Under the microscope the berry is seen to consist of a hard, tough tissue,
that resists even long soaking. The testa covering the berry is made of
lengthened cells with oblique markings resting on a thin membrane, almost
structureless. These oblique markings of the cells are so characteristic
as to render the cells distinguishable from every other tissue. The
substance of the berry consists of angular cells, each one of which
contains minute drops of oil. This oil is in some measure driven off
during the process of roasting, which, however, leaves the structure
unimpaired where it is not charred.
[Illustration]
Roasted corn, beans, &c., may be detected by the cold decoction striking a
blue colour with tincture of iodine. Pure coffee is merely deepened a
little in colour by this substance.
4. (A. H. Allen.) The amount of ash in genuine coffee does not exceed 4·5
per cent.; chicory yields 5 per cent. The silica in coffee ash never
exceeds 1 per cent., while in chicory it varies from 10-36 per cent. The
average soluble ash in coffee is 3·24, while in chicory it is 1·74 per
cent. By determining the soluble ash S, the per-centage of pure coffee C
may be calculated thus:--
(100 S - 174)
C = 2 ---------------
3
The density of coffee-infusion is determined by heating the powder with 10
times its weight of cold water, raising the liquid to the boiling point,
filtering, and taking the gravity at 15·5° C. Taking the density of pure
coffee-infusion at 1008·6, and that of chicory at 1020·6, the per-centage
of pure coffee C in the sample may be calculated from the equation
100(1020 - D)
C = ------------
12
where D represents the density of the infused sample. The relative
tinctorial power of an infusion of a sample of coffee is determined by
boiling a given weight with 20 c. c. of water for a few minutes,
filtering, and again boiling the residue until thoroughly exhausted. An
equal weight of a standard mixture of equal weights of pure coffee and
chicory is treated in a precisely similar manner. The standard solution
is made up to 200 c. c., that of the sample to 100 c. c.; 10 c. c. of the
latter are put into a narrow burette, and some of the standard into a test
tube of exactly equal bore. If the tints are exactly the same, the sample
consisted of pure coffee; if chicory is present, water must be added to
the sample until the tints are the same. Each c. c. of water represents 5
per cent. of chicory. The presence of leguminous seeds or cereals may be
detected by boiling the sample with animal charcoal and water, filtering,
and testing for starch in the cold liquid with iodine. Neither coffee nor
chicory contains starch.
_Obs._ A few years ago the attention of the scientific world was drawn to
the value of roasted coffee leaves, as furnishing materials for a beverage
unexcelled in excellence by the coffee berry itself. It appears that the
leaves, prepared for use, may be purchased for 1-1/2d. per lb., or packed
ready for export at 2d. per lb. "That this preparation contains a
considerable amount of the nutritious principles of coffee is evident from
the analysis; but as the leaves can only be collected in a good state at
the expense of the coffee-bush, it is doubtful whether the coffees
produced by the berries be not, after all, the cheapest, as it certainly
is the best." (Jury Report, Exhibition, 1851.) Coffee for the table is
best prepared with the aid of a French cafetière, or coffee biggin,
furnished with a percolator or strainer, which will permit a moderately
rapid filtration. To produce this beverage in perfection, it is necessary
to employ the best materials in its preparation--fresh roasted and fresh
ground. "At least 1 oz. of coffee should be used to make 3 common-sized
coffee-cupfuls, with 1 teaspoonful of freshly roasted and ground chicory.
If desired strong, the quantity of both should be doubled." (Cooley.) Many
habitual coffee drinkers cannot tolerate the use of chicory, which is a
doubtful improver of coffee. The prevailing fault of the coffee made in
England is its want of strength and flavour. The coffee-pot should be
heated previously to putting in the coffee, which may be done by means of
a little boiling water. The common practice of boiling coffee is quite
unnecessary, for all its flavour and aroma is readily extracted by boiling
hot water. Indeed, all the "useful and agreeable matter in coffee is very
soluble, it comes off with the first waters of infusion, and needs no
boiling." (Ure.) Should prejudice, however, induce the housewife or cook
to boil her coffee, it should be only just simmered for a minute, as long
or violent boiling injures it considerably.
When coffee is prepared in a common pot, the latter being first made hot,
the boiling water should be poured over the powder, and not, as is
commonly the plan, put in first. It should then be kept stirred for 4 or 5
minutes, when a cup should be poured out and returned again, and this
operation repeated 3 or 4 times, after which, if allowed to repose for a
few minutes, it will generally become fine of itself. In all cases, where
a percolator is not used, the liquor should be well stirred up several
times before finally covering it up to settle for use.
Amongst the various descriptions of coffee pots in use we may mention
those of French make, consisting of two cylindrical vessels, the upper
having a metal strainer, on which the ground coffee is placed, and through
which the clear infusion runs into the lower one; Loysell's--an apparatus
making very good coffee, and as one of the latest, an ingenious and
inexpensive coffee pot, known as the "Kaffee Kanne," devised by Mr Ash, of
Oxford Street. Ash's "Kaffee Kanne" consists of an ordinary biggin,
surrounded by a jacket containing boiling water. The coffee is made by
percolation in the inner vessel, and being kept at the point of ebullition
by the surrounding boiling water, yields a beverage of excellent flavour
and aroma.
Coffee is sometimes clarified by adding a shred of isinglass, a small
piece of clean eel- or sole-skin, or a spoonful of white of egg. An
excellent plan, common in France, is to place the vessel containing the
made coffee upon the hearth, and to sprinkle over its surface half a
cupful of cold water, which from its greater gravity descends, and carries
the 'foulness' with it. Another plan sometimes adopted is to wrap a cloth,
previously dipped into cold water, round the coffee-pot. This method is
commonly practised by the Arabians in the neighbourhood of Yemen and Moka,
and rapidly clarifies the liquor, unless a very large quantity of chicory
is present. It should be recollected that the use of isinglass, white of
egg, and all like artificial finings, remove much of the astringency and
vivacity of the liquor.
The French, who are remarkable for the superior quality of their coffee,
generally allow an ounce to each large coffee-cupful of water, and they
use the coffee both newly ground and freshly roasted. A shred of saffron,
or a little vanilla, is frequently added, whilst the percolating
coffee-pot is generally employed. When the Parisian uses a common
coffee-pot he generally divides the water into 2 parts. The first portion
he pours on boiling hot, and allows it to infuse for 4 or 5 minutes; he
then pours this off as clear as possible, and boils the grounds for 2 or 3
minutes with the remaining half of the water. As soon as this has
deposited the sediment it is decanted, and mixed with the infusion. The
object of this process is to obtain the whole of the strength as well as
the flavour. The infusion is thought to contain the latter, and the
decoction the former; a plausible, but erroneous idea, since both of them
were carried off by the first water.
A much better method, and one we can recommend from experience, is to
divide the coffee into 2 parts. Boil the first portion in the coffee-pot
for 4 or 5 minutes, then add the other portion, and allow it to infuse
slowly for about 10 minutes, the coffee-pot lid being kept well closed.
This gives a coffee possessing a flavour which even the French cannot
excel.
=Coffee, Essence of.= A highly concentrated infusion of coffee, prepared
by percolation with boiling water, gently and quickly evaporated to about
1/3rd or 1/4th of its bulk, and mixed with a thick aqueous extract of
chicory and syrup of burnt sugar, so as to give the whole the consistence
of treacle. The proportions of the dry ingredients should be--coffee, 4
parts; chicory, 2 parts; burnt sugar (caramel) 1 part. It should be kept
in well-corked bottles in a cool place. This preparation is very
convenient for making extemporaneous coffee; but the beverage so made,
though superior to much of that sold at coffee-houses, is inferior in
flavour, aroma, and piquancy, to that we are accustomed to drink at home.
Much of the so-called 'Essence of Coffee' is simply treacle and burnt
sugar, flavoured with coffee.
=Coffee, Searle's Patent.= This is prepared by mixing condensed milk with
a very concentrated essence of coffee and evaporating at a low temperature
(_in vacuo_, if possible), until the mixture acquires the consistence of a
syrup (coffee syrup), paste (coffee paste), or candy (coffee candy). The
last may be powdered (coffee powder, dry essence of coffee).
=Coffee, Substitutes for.= These are numerous, but are now seldom
employed, owing to the cheapness of the genuine article, and the
stringency of the revenue laws. Among the principal are the following:--
1. COFFEE, ACORN. From acorns deprived of their shells, husked, dried, and
roasted.