ees.

_The Aromatic Principles of Coffee_

To ascertain just what substance or substances give the pleasing and
characteristic aroma to coffee has long been the great desire of both
practical and scientific men interested in the coffee business. This
elusive material has been variously called caffeol, caffeone, "the
essential oil of coffee," etc., the terms having acquired an ambiguous
and incorrect significance. It is now generally agreed that the aromatic
constituent of coffee is not an essential oil, but a complex of
compounds which usage has caused to be collectively called "caffeol."

These substances are not present in the green bean, but are produced
during the process of roasting. Attempts at identification and location
of origin have been numerous; and although not conclusive, still have
not proven entirely futile. One of the first observations along this
line was that of Benjamin Thompson in 1812. "This fragrance of coffee is
certainly owing to the escape of a volatile aromatic substance which did
not originally exist as such in the grain, but which is formed in the
process of roasting it." Later, Graham, Stenhouse, and Campbell started
on the way to the identification of this aroma by noting that "in common
with all the valuable constituents of coffee, caffeone is found to come
from the soluble portion of the roasted seed."[145]

Comparison of the aroma given off by coffee during the roasting process
with that of fresh-ground roasted coffee shows that the two aromas,
although somewhat different, may be attributed to the same substances
present in different proportions in the two cases. Recovery and
identification of the aromatic principles escaping from the roaster
would go far toward answering the question regarding the nature of the
aroma. Bernheimer[146] reported water, caffein, caffeol, acetic acid,
quinol, methylamin, acetone, fatty acids and pyrrol in the distillate
coming from roasting coffee. The caffeol obtained by Bernheimer in this
work was believed by him to be a methyl derivative of saligenin.
Jaeckle[147] examined a similar product and found considerable
quantities of caffein, furfurol, and acetic acid, together with small
amounts of acetone, ammonia, trimethylamin, and formic acid. The caffeol
of Bernheimer could not be detected. Another substance was separated
also, but in too small a quantity to permit complete identification.
This substance consisted of colorless crystals, which readily