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The Decaffeination Process
The oldest method of
decaffeinating coffee is that
used by Kaffee Hag, among
others, in which carbon dioxide,
pressurized to a supercritical nearly-fluid state, is forced through
steamed green beans, removing the caffeine. Many companies do not use this
method simply because the equipment and facilities required are so
expensive.
The most widespread means of decaffeination occurs when warmed or steamed
green beans are soaked in a solution containing a chemical solvent,
usually methylene chloride, which is selective in its target: all but
about three per cent of the caffeine, and practically none of the flavor,
passes into the solvent. The beans, rinsed and dried, go on to be roasted,
and almost any trace of the solvent remaining with the beans is destroyed
in the high roasting temperatures.
In 1995 this method was banned in
Europe because methylene chloride vapors, particularly in aerosol form,
destroy the ozone layer. The United States Food and Drug Administration
has limited methylene chloride residues in brewed coffee to ten parts per
million, a figure which does not worry most coffee processors, who insist
the actual residue is already less than one-millionth part anyway.
The slowest, and therefore most expensive, form of decaffeination is the
patented Swiss Water Method, which uses only steamed beans,
hot water and carbon filters to
remove the caffeine.
Unfortunately, some of the
volatile flavor compounds also
go with the caffeine, so the
water is evaporated, and the
remaining flavor concentrate
is then sprayed on to the
decaffeinated beans.
Although coffee lovers
and experts alike are still
convinced that decaffeination destroys the taste of coffee, many would
find it extremely difficult to differentiate between a "regular" coffee
and its "unleaded" version. In an exhaustive tasting project carried out
over a period of several weeks at the International Coffee Organization,
United Kingdom, a panel of trained tasters compared three cups of coffee,
each made from beans from the same crop and same plantation; one cup was
coffee decaffeinated with a solvent, one was water-processed
decaffeinated, and the third was regular un-decaffeinated coffee. The
tests were carried out time and again, not just with one set of coffee
samples, but with coffees from Kenya, Colombia and Brazil. The results
showed that often tasters could not tell which cups contained
decaffeinated coffee, and, further, when tasters thought they could
distinguish a difference, if asked for a preference, they often preferred
the taste of the chemically decaffeinated coffee to the "regular" version
of the same coffee.
Anyone who loves the taste of coffee, but is concerned about the effects
of caffeine, should realize that today there are some fabulous
decaffeinated coffees available, particularly from specialist
shops. Cover the label,
hide the box, and enjoy one of the luxuries of life: a cup of good coffee.
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