Decaffeination is the act of removing caffeine from coffee beans.
All decaffeination processes are performed on unroasted (green) coffee beans,
but the methods vary somewhat. It generally starts with the steaming of the
beans. They are then rinsed in solvent that contains as much of the chemical
composition of coffee as possible without also containing the caffeine in a
soluble form. The process is repeated anywhere from 8 to 12 times until it meets
either the international standard of having removed 97% of the caffeine in the
beans or the EU standard of having the beans 99.9% caffeine free by mass. Coffee
contains over 400 chemicals important to the taste and aroma of the final drink;
this effectively means that no chemical reaction will remove only caffeine while
leaving the other chemicals at their original concentrations. While they are
occasionally referred to informally as "decaffeinated," soft drinks
without caffeine are prepared by simply leaving caffeine out in the first place.
Coffea arabica normally contains about half the caffeine of Coffea robusta.
A Coffea arabica bean containing little caffeine has been found recently in
Ethiopia. This may change how low-caffeine coffee is produced in the future.
Additionally, genetic engineering technology may be eventually applied to create
a naturally caffeine-free coffee. But for now, one of several methods to remove
the caffeine from caffeine-containing beans is employed.
The first commercially successful decaffeination process was invented by Ludwig
Roselius and Karl Wimmer in 1903. It involved steaming coffee beans with a brine
(salt water) solution and then using benzene as a solvent to remove the caffeine.
Coffee decaffeinated this way was sold as Cafe sanka in France and later as
Sanka brand coffee in the US. Due to health concerns regarding benzene, this
process is no longer used commercially and Sanka is produced using a different
Swiss Water Process
The Swiss Water Process uses only water to remove caffeine. Although the process
originated in Switzerland in the 1930s, today the world´s only Swiss Water decaffeination
facility is based near Vancouver, Canada.
In the direct method the coffee beans are first steamed for 30 minutes and then
repeatedly rinsed with either methylene chloride or ethyl acetate for about
10 hours. The solvent is then drained away and the beans steamed for an additional
10 hours to remove any residual solvent. Sometimes, coffees decaffeinated using
ethyl acetate are misleadingly referred to as "naturally processed"
because ethyl acetate can be derived from various fruits or vegetables. However,
for the purpose of decaffeination, it is not possible to create such a large
quantity of ethyl acetate, thus the chemical is synthetically derived.
In the indirect method beans are first soaked in hot water for several hours,
essentially making a strong pot of coffee. Then the beans are removed and either
methylene chloride or ethyl acetate is used to extract the caffeine from the
water—as in other methods, the caffeine can then be separated from the
organic solvent by simple evaporation. The same water is recycled through this
two-step process with new batches of beans. An equilibrium is reached after
several cycles, where the water and the beans have a similar composition except
for the caffeine. After this point, the caffeine is the only material removed
from the beans, so no coffee strength or other flavorings are lost. Because
water is used in the initial phase of this process, sometimes indirect method
decaffeination is referred to as "water processed" even though chemicals
With the CO2 process, pre-steamed beans are soaked in a liquid bath of carbon
dioxide at 73 to 300 atmospheres. After a thorough soaking, the pressure is
reduced allowing the CO2 to evaporate, or the pressurized CO2 is run through
either water or charcoal filters to remove the caffeine. The carbon dioxide
is then used on another batch of beans. This same process can also be done with
oxygen (O2). These liquids work better than water because they are kept in supercritical
state near the transition from liquid to gas so that they have the high diffusion
of gas and the high density of a liquid.
Green coffee beans are soaked in a hot water/coffee solution to draw the caffeine
to the surface of the beans. Next, the beans are transferred to another container
and immersed in coffee oils that were obtained from spent coffee grounds.
several hours of high temperatures, the triglycerides in the oils remove the
caffeine - but not the flavor elements - from the beans. The beans are separated
from the oils and dried. The caffeine is removed from the oils, which are reused
to decaffeinate another batch of beans. This is a direct contact method of decaffeination.
Not caffeine free
Almost all brands of decaffeinated coffee still contain some caffeine. Drinking
five to ten cups of decaf could deliver as much caffeine as one or two cups
of regular coffee, according to research at the University of Florida Maples
Center for Forensic Medicine.