The Decaffeination Process

The Decaffeination Process

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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