Caffeine in
Coffee
by James Grierson
Caffeine is only one of
several hundred chemicals found in coffee. However it is the
most notorious because of the many physiological affects it has
on the human body. Caffeine
naturally occurs in many other plants apart from the coffee
bush, such as tea and cocoa plants.
There is a long established link between coffee and mental
stimulation, which gives a cup of coffee a certain appeal. In
fact it could be argued that coffee drinking has helped change
the course of history. In 1773, it was in a Boston coffee house
where citizens planned the Boston Tea Party; and in 1789, it
was from Café Foy that Camille Desmoulins led the angry mob
that later brought down the Bastille.
Whether caffeine is actually good for us is a long and much
argued debate. Caffeine is commonly used by endurance athletes
to permit them to train for longer and aid their recovery
afterwards. Scientific studies have also linked it to the
prevention of Parkinson's and Alzheimer's disease. However, too
much caffeine can lead to insomnia, diuresis, gastro-intestinal
disturbance, arrhythmia, psychomotor agitation and
osteoporosis.
The amount of caffeine in an average cup of coffee (8oz/230ml)
varies from between 80 to 150 milligrams. This variation is due
to a number of factors. The main difference is caused by from
where, and from which variety of plant, the coffee beans are
harvested. As caffeine has natural anti-fungal properties,
coffee plants grown in environments less favourable to the
growth of fungal spores contain less caffeine. At high
altitudes, the temperature and humidity is such that spores
germinate too slowly to have too much of an effect on a coffee
plant. So, generally speaking, the higher the altitude at which
a bean is grown, the lower its caffeine content. Also Arabica
beans typically have half the amount of caffeine when compared
to Robusta beans.
The roasting process alters the amount of caffeine in a coffee
bean. A common misconception is that, the darker the roast
level, the lower the caffeine content. However, this is not
really the case as caffeine changes very little during the
roasting process. Caffeine has a very stable structure with a
boiling point above 315°C, well above roasting temperatures,
which rarely exceed 245°C. Nevertheless a small amount of
caffeine is lost due to sublimation, where a substance changes
directly from a solid state to a gaseous one. This occurs in
caffeine at approximately 175°C.
The roasting process dramatically alters a coffee bean. A bean
loses weight, mostly due to water evaporation, causing the
level of caffeine by weight to increase. However, as beans
nearly double in size when roasting, the level of caffeine by
volume decreases.
The final factor affecting the caffeine content of your cup of
coffee is the brewing method. Different brewing methods require
different amounts of coffee, ground to different sizes. Many
people believe that an espresso contains less caffeine then a
regular cup of coffee. But as you require more coffee to make
an espresso then a regular cup, and the coffee is ground finer,
increasing the surface area, this means that the caffeine
content is roughly the same. However the effects will be felt
more quickly with an espresso, and wear off faster, as caffeine
is absorbed more rapidly when taken in concentrated doses.
About the author:
James Grierson is the owner of Galla Coffee: http://www.gallacoffee.co.uk
- Uk online retailer of designer coffee accessories. Through
the Coffee Knowledge section of his website he aims to help
people understand more about coffee and give them tips on how
to make great tasting coffee in their home.
Check out http://www.gallacoffee.co.uk/acatalog/Coffee_Knowledge.html
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