CHEMISTRY AND PHARMACOLOGY OF COFFEE
_The chief factors which enter into coffee
goodness—Brief discussion of caffein and
caffeol—Coffee’s place in a rational dietary—Latest
scientific discoveries which establish the whole
truth about coffee as a wholesome, satisfying drink
for the great majority of people and cause it to be
regarded as the servant, rather than the destroyer,
of civilization._
Generally speaking, the trade and the consumer are concerned chiefly
with those factors which enter into coffee goodness. These are the
caffein content and the caffeol. Caffein supplies the principal
stimulant. It increases the capacity for muscular and mental work
without harmful reaction. The caffeol supplies the flavor and the
aroma,—that indescribable oriental fragrance that woos us through the
nostrils, forming one of the principal elements that make up the lure
of coffee. There are several other constituents, including certain
innocuous so-called caffetannic acids, which, in combination with the
caffeol, give the beverage its rare gustatory appeal.
In the roasting of green coffee, part of the original caffein content
is lost by sublimation (vaporizing), and caffeol is formed. Chemists
recognize two groups of constituents which are formed during roasting
and are soluble in water,—heavy extractives and light aromatic
materials.
The heavy extractives include caffein, mineral matter, proteins,
caramel, and sugars, “caffetannic acid,” and various organic materials.
Some fat will also be found in the average coffee brew, melted from the
bean by the heated water and carried along with the solution. The light
extractives are collectively known as caffeol.
Caffein has a slightly bitter taste, but, because of the small
percentage present in a cup of coffee, it contributes little to its cup
value. Nevertheless, it furnishes the stimulation for which coffee is
generally consumed. The caffein content of _Coffea arabica_, green, is
1.5 percent.
The mineral matter, together with certain decomposition and hydrolysis
products of crude fiber and chlorogenic acid, contribute toward the
astringency or bitterness of the cup. The proteins are present in such
small quantity that their only role is to raise somewhat the almost
negligible food value of a coffee infusion. The body, or what might be
called the licorice-like character, of coffee is due to the presence
of bodies of a glucosidic nature and to caramel. The degree to which a
coffee is sweet-tasting or not is, of course, dependent upon its other
characteristics, but probably varies directly with the reducing sugar
content.
The term “caffetannic acid” is a misnomer, for the substances called by
this name are in all probability mainly coffalic and chlorogenic acids,
neither of which is a true tannin, nor do they evince but few of the
characteristic reactions of tannic acid. Some neutral coffees will show
as high a “caffetannic acid” content as other acid-charactered ones.
Careful chemical analysis has shown that the actual acidities of some
East Indian coffees vary from 0.013 to 0.033 percent. These figures
my be taken as reliable examples of the true acid content of coffee,
and, though they seem very low, it is not at all incomprehensible
that the acids they indicate produce the acidity in a cup of coffee.
They probably are mainly volatile organic acids together with other
acidic-natured products of roasting.
We know that very small quantities of acid are readily detected in
fruit juices and beer, and that variation in their percentages is
quickly noticed, while the neutralization of this small amount of
acidity leaves an insipid drink. Hence it seems quite likely that this
small acid content gives to the coffee brew its essential acidity. A
few minor experiments on neutralization have proved the production of
a very flat beverage by thus treating a coffee infusion. Acidity of
certain coffees most apparently should be attributed to such compounds
rather than to the miscalled “caffetannic acid.” For personal proving
of this statement, put a small pinch of the weakly alkalin baking soda
(NaHCO₃) into a cup of coffee and note the difference that it makes.
The light aromatic materials and other substances that are
steam-distillable (i. e., which are driven off when coffee is
concentrated by boiling) are important factors in determining the
individuality of coffees. These compounds (caffeol) vary greatly in
the percentages present in different coffees, and thus are largely
responsible for our ability to distinguish coffees in the cup. It is
these compounds that supply the pleasingly aromatic and appetizing odor
to coffee.[1]
[1] Ukers: _All About Coffee_ (p. 718-19, 1922).
Like all good things in life, the drinking of coffee may be abused.
Indeed, those having an idiosyncratic susceptibility to alkaloids
should be temperate in the use of tea, coffee, or cocoa. In every
high-tensioned country, there is likely to be a small number of people
who, because of certain individual characteristics, cannot drink coffee
at all. These belong to the abnormal minority of the human family. Some
people cannot eat strawberries, but that would not be a valid reason
for a general condemnation of strawberries. One may be poisoned, says
Thomas A. Edison, from too much food. Horace Fletcher was certain that
overfeeding caused all our ills. Overindulgence in meat is likely to
spell trouble for the strongest of us. Coffee is, perhaps, less often
abused than wrongly accused. It all depends. A little more tolerance!
Trading upon the credulity of the hypochondriac and the caffein
sensitive, in recent years there has appeared in America and abroad a
curious collection of so-called coffee substitutes. They are “neither
fish, nor flesh, nor good red herring.” Most of them have been shown
by official government analyses to be sadly deficient in food value,
their only alleged virtue. One of our contemporary attackers of the
national beverage bewails the fact that no palatable hot drink has been
found to take the place of coffee. The reason is not hard to find.
There can be no substitute for coffee. Dr. Harvey W. Wiley has ably
summed up the matter by saying, “A substitute should be able to perform
the functions of its principal. A substitute in a war must be able to
fight. A bounty jumper is not a substitute.”
A brief summarization of available information on the pharmacology of
coffee indicates that it should be used in moderation, particularly
by children, the permissible quantity for adults varying with the
individual, his constitution, mode of living, etc., and ascertainable
only through personal observation.
Recent scientific research has destroyed many bugaboos manufactured by
the traducers of our national beverage; for one, the alleged harmful
effects of the caffein content. We now know that the small amount of
caffein in the coffee cup is distinctly beneficial to the majority and
that it is a pure stimulant having no harmful reaction.
Then there was the notion that cream in coffee made the beverage
indigestible. The statement was made that milk or cream caused the
coffee liquid to become coagulated when it came into contact with the
acids of the stomach. This is true, but it does not carry with it the
inference that indigestibility accompanies this coagulation. Milk and
cream, upon reaching the stomach, are coagulated by the gastric juice,
but the casein product formed is not indigestible. These liquids,
when added to coffee, are partly acted upon by the small acid content
of the brew, so that the gastric juice action is not so pronounced,
for the coagulation was started before ingestion, and the coagulable
constituent, casein, is more dilute in the cup as consumed than it is
in milk. Accordingly, the particles formed by it in the stomach will be
relatively smaller and more quickly and easily digested than milk _per
se_.
Used in moderation, coffee has invariably proved a valuable stimulant,
increasing personal efficiency in mental and physical labor. Its
action in the alimentary regime is that of an adjuvant food, aiding
digestion, favoring increased flow of the digestive juices, promoting
intestinal peristalsis, and not tanning any part of the digestive
organs. It reacts on the kidneys as a diuretic, and increases the
excretion of uric acid; which, however, is not to be taken as evidence
that it is harmful in gout. Coffee has been indicated as a specific
for various diseases, its functions therein being the raising and
sustaining of low vitalities. Its effect upon longevity is virtually
nil. A small proportion of humans who are very nervous may find coffee
undesirable, but sensible consumption of coffee by the average, normal,
non-neurasthenic person will not prove harmful but beneficial.
Until the campaign of education recently conducted by coffee men in the
United States, many neurotics received with gladness the tales of the
harmfulness of coffee. They eagerly welcomed the doubtful substitutes,
coffee minus the caffein, or some nauseating cereal preparation. They
were convinced that by avoiding coffee they could cure their nervous
condition.
Commenting upon the campaign of enlightenment, the _New York Medical
Journal & Medical Record_ said:
This whole question has been exaggerated. Coffee in
moderation does not produce nervous ailments. Removal
of coffee from the diet does not cure them. Coffee
with cream and sugar is a source of food and energy.
In many cardiac and nephritic conditions there is
no better or simpler preparation than well prepared
coffee.
It is amusing to see chocolate, cocoa, and even tea
substituted for coffee in various nervous or other
conditions, when as a matter of fact the amount of
stimulus cup for cup is the same or even greater.
What foundation there is for giving children and old
persons various chocolate preparations in place of
coffee is difficult to determine.
It would be well to look at the coffee question
squarely and not cover the situation by inane
avoidances. Coffee is one of the mainstays of our
rapid civilization. Those adults who wish to live and
enjoy life, let them drink their coffee in peace.
Those who wish to ascribe illness or nervousness to
magical causes, let them abandon it.
This is an able summing up of the question of the alleged harmfulness
of coffee. Those who may wish to examine the evidence pro and con will
find it detailed in the chapter on the pharmacology of coffee in _All
About Coffee_. Opinions, names, and full references are given there.
_The Whole Truth about Coffee_
For more than three years the Massachusetts Institute of Technology
made an exhaustive investigation of coffee. This investigation was made
at the invitation of the coffee trade of the United States to determine
by scientific research the whole truth about coffee and coffee making.
It involved a total cost of $40,000 and was one of the most thorough
investigations ever made of any food product.
The result of this scientific research, as announced by Professor
Samuel C. Prescott, director of the institute’s Department of Biology
& Public Health, shows that coffee is a wholesome, helpful, satisfying
drink for the great majority of people.
The report covers many hundreds of pages, for every aspect of
coffee and coffee making was studied, but in just one paragraph of
92 words Professor Prescott swept aside all the old prejudices and
superstitions, and gave coffee the cleanest bill of health that could
be wished. He said:
It may be stated that, after weighing the
evidence, a dispassionate evaluation of the data
so comprehensively surveyed has led to no alarming
conclusions that coffee is an injurious beverage
for the great mass of human beings, but on the
contrary that the history of human experience, as
well as the results of scientific experimentation,
point to the fact that coffee is a beverage which,
properly prepared and rightly used, gives comfort and
inspiration, augments mental and physical activity,
and may be regarded as the servant rather than the
destroyer of civilization.
[Illustration: 800,000 COFFEE TREES IN BEARING AT GUATAPARA, BRAZIL]