Decaffeinated coffee
Coffee naturally contains the active supplement caffeine. The stimulating power of
coffee is as well known as the outstanding taste. A lot of coffee lovers appreciate
this stimulating power, but there are some people that do not handle caffeine so
well or do not like the stimulating effect every time of the day. For them there is
decaffeinated coffee on the market. This decaffeinated coffee lacks the stimulating
power of caffeine.
Normal coffee beans contain between 0.8 percent and 2.5 percent caffeine
depending on origin and variety. Decaffeinated coffee is not entirely caffeine-free.
In European Community (EC) countries, roasted decaffeinated coffee may contain a
caffeine residue of 0.1 percent and coffee extract 0.3 percent.
Decaffeination processes
To make coffee caffeine free, the stimulating supplement needs to be derived from
the beans. Since coffee develops most of its flavour during roasting, the caffeine is
extracted from the raw green coffee beans. Various methods exist to achieve this,
of which the water-carbon (H2O/C) and dichloromethane (commonly known as
DCM) methods are the most used. Both of these techniques extract the caffeine
with a caffeine-selective solvent, which therefore leaves the other substances in the
bean. Modern decaffeinating methods have no effect upon the flavour and aroma of
the coffee. Good decaffeinated coffee therefore tastes almost the same as coffee
containing caffeine.
Water-carbon method
This process uses water (H2O) as a solvent. The green beans are rinsed with water
for a long period, during which time the caffeine dissolves into the water. The
water, with its dissolved caffeine, is then pumped through an active carbon (C)
filter which absorbs the caffeine. The decaffeinated beans are dried using warm air
and then cooled with cold air. They are then roasted, ground and packed in the
usual way. The water is re-used for the decaffeination process.
Dichloromethane process
This method employs dichloromethane (DCM) as a solvent and has been developed
to suit the requirements of the out of home industry. The green beans are
moistened with water in order to make the surface of the bean porous, and soaked
in the solvent for 30 minutes. This is repeated several times. The beans are
removed from the solvent once the caffeine has dissolved. They are then steamed
for some time in order to remove any remaining solvent. Afterwards the beans are
dried using warm air, then cooled with cold air. They are roasted, ground and
packed in the usual way. The dichloromethane is reused for further decaffeinating.
source: Douwe Egberts
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