Jewish World Review Feb. 19, 2002 / 7 Adar, 5762
Dr. Ed Blonz
Dear S.A.: A population study in the journal Arthritis and Rheumatism (January 2002) reported a increased risk of rheumatoid arthritis in women drinking more than four cups of decaffeinated coffee per day. It was a finding of the Iowa Women's Health Study, but no other research has made this connection. No relationship found between drinking caffeinated coffee and getting arthritis, and those drinking tea were found to have a decreased risk. With this type of study it is unclear what, if anything, is causing what.
Thus, it's inappropriate to conclude that decaffeinated coffee might increase the risk of developing rheumatoid arthritis. Aside from this study, there do not appear to be any additional health risks associated with drinking decaffeinated coffee.
We should discuss the ways in which coffee and tea are decaffeinated. One thing they share is a need for a solvent that does a good job of dissolving caffeine. This solvent can be water, methylene chloride, ethyl acetate, triglycerides, or pressurized carbon dioxide. An indirect method involves taking a load of green coffee beans and placing them in a quantity of water. All water-soluble substances -- including caffeine -- is then drawn into this water. At this point, the solution includes components that give coffee its desirable aroma and flavor. This solution is removed from that first batch of coffee beans, and those beans are discarded.
The next step is to remove only the caffeine from the solution, which is accomplished by using a selective caffeine solvent that effectively pulls the caffeine out of the water. The caffeine-rich solvent is then separated from the water extract.
At this point, the water extract contains the water-soluble portions of the coffee bean -- minus caffeine. This now becomes the working solution into which the next batch of (caffeine-containing) green beans are placed. Only the caffeine gets extracted in this second mixture, as all other components are already there and will exist in a state of equilibrium between what is in the beans and what is already in the solution. This second solution then goes through its caffeine extraction, and the process continues with subsequent batches.
Another indirect process is called the Swiss water process. It is similar to the above, except that the caffeine is not removed from the water mixture by solvents. The Swiss water process passes the caffeine-rich water mixture through charcoal filters pre-treated with substances that grab the caffeine. The caffeine-free water mixture is then mixed with the next batch of green coffee beans, and the process continues.
The direct method involves mixing the selective caffeine solvent directly with the beans (or tea leaves). Methylene chloride and ethyl acetate are the solvents most often used.
After it has had a chance to dissolve the caffeine, the solvent is removed, and the beans/tea leaves are steamed gently to eliminate any remaining solvent residue.
Methylene chloride is a carcinogen, but there shouldn't be any left to pose a health risk. This is because methylene chloride evaporates at around 110 F -- well bellow steaming temperature and well below the temperature at which coffee and tea is brewed.
Ethyl acetate is a compound that occurs naturally in fruits and vegetables and is the one most often used with tea leaves. In all the above, the green beans or tea leaves are ready for drying, roasting or further processing after the caffeine is removed.
There is a newer, more expensive method that utilizes carbon dioxide that has been liquefied under high pressure. (This is the only process approved for organic coffee and tea production.) The liquefied carbon dioxide dissolves the caffeine from the tea leaves or coffee beans and is then drained off. Yet another method utilizes the fatty substances called triglycerides. Whatever the method, decaffeination technology has improved greatly over the years, and flavor differences may be hard to detect. Much also depends on the quality of the beans and tea leaves, together with the particular practices of the roaster.
Note that the use of the term "water process" with decaffeinated beans doesn't tell you the whole story, as most indirect methods utilize a water extraction somewhere along the way. If the label states "Swiss water process" or has other additional information, a better determination can be
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