Mocha.East Indian.
Raw.Roasted.Raw.Roasted.
per cent.per cent.per cent.per cent.
Caffeine1·080·821·111·05
Saccharine matter9·550·438·900·41
Caffeic acids8·464·749·584·52
Alcohol extract
(containing nitrogen
and colouring matter).		6·9014·144·3112·67
Fat and oil12·6013·5911·8113·41
Legumin or Albumin9·8711·2311·2313·13
Dextrine0·871·240·841·38
Cellulose (and
insoluble colouring
matter).		37·9548·6238·6047·42
Ash3·744·563·984·88
Moisture8·980·639·641·13
100·00100·00100·00100·00

Other authorities have obtained the following results:—

König.Payen.
Raw.		 Smethan.
(Average of
7 Varieties.)
Roasted.
Raw.Roasted.
per cent.per cent.per cent.per cent.
Substances soluble in water27·4427·45....
Nitrogen1·872·31..2·26
Nitrogenous substances11·4312·0511 to 13..
Caffeine1·181·380·8..
Caffetannic acid....3·5 to 5..
Fat13·2315·0310 to 1310·99
Ethereal oil....0·013..
Sugar3·251·32....
Sugar and Dextrine....15·5..
Other non-nitrogenous
substances.		31·5238·41....
Cellulose27·7224·2734·029·28
Ash3·483·756·74·19
Soluble ash......3·37
Moisture11·193·1912·02·87

It will be noticed from these analyses that the amount of sugar is greatly diminished by the process of roasting. According to some analysts, the proportion of fat experiences an increase, but it is more probable that this constituent is simply rendered more susceptible to the action of solvents by a mechanical alteration of the structure of the berry. Recent determinations of the ash in coffee place its average proportion at 4 per cent.; 3·24 being soluble in water, and 0·74 per cent. insoluble. The soluble extract in roasted coffee usually amounts to about 30 per cent.

An analysis made by Beckurts and Kauder[10] gives the general composition of roasted chicory, dried at 107°, as follows:—

Per cent.
Substances soluble in water57·40
„ insoluble „41·90
Ash7·66
Fat0·73
Nitrogenous substances7·12
Grape sugar4·35
Cane sugar and dextrine5·33
Starch2·45
Other non-nitrogenous substances49·13
Woody fibre26·23

The most common adulterations to which coffee is liable consist in the addition of chicory, caramel, and numerous roasted grains, such as corn, wheat, and rye, as well as such roots and seeds as dandelion, mangold wurzel, turnips, beans, peas, etc. The roasted and ground article is naturally most exposed to falsification, although letters patent have been issued for the fictitious manufacture of a pressed “coffee bean,” containing absolutely no coffee. The addition of chicory is by far the most prevalent adulteration of coffee. Of thirty-four samples examined by Hassall, thirty-one (91 per cent.) contained this root. In regard to the moral aspects of its use, it can safely be asserted that, while the addition of chicory to coffee is largely sanctioned, and indeed demanded by the existing tastes of many coffee-drinkers, its use constitutes a true adulteration, and should be condemned, unless its presence is prominently stated on the label of the package. In chicory the active principles of coffee, which exert valuable physiological effects on the system (viz. caffeine, the essential oil, etc.), are totally absent; moreover, its comparative cheapness is a constant temptation to employ a proportion largely in excess of the amount requisite to produce any alleged improvement in the flavour of the resulting admixture.

The sophistications of coffee may be detected, in a general way, by physical tests, by chemical analysis, and by microscopic examination, in which processes great aid is derived from the characteristic properties exhibited by the pure roasted and ground berry which distinguish it from its more usual adulterants.

(a) Physical Examination.—The following tests, while not always decisive in their results, are often of service.