Methylene Chloride Decaffeination

Bad Process or Bad Press? As soon as anyone mentions a method of chemical decaffeination these days, people immediately become alarmed. Coffee that is decaffeinated with chemicals seems ‘bad´ and coffee decaffeinated with water or CO2 is ‘good´.

Peoples decision to not like chemically decaffeinated coffee is often to do with the bad press it receives. I have read that chemically decaffeinated coffee causes cancer and that the chemical that was used in decaffeination was banned for use in hairspray.

I still have mixed emotions. Friends in the coffee trade tell me that methylene chloride decaffeinated coffee tastes the best, is the least expensive and poses NO health risks. It sounds great, but I still have a hard time getting past the chemical.


What is Methylene Chloride?

Methylene Chloride is a colourless liquid with a slightly sweet aroma. It has a boiling oint of 104°F.


How is it used to decaffeinate green coffee?

The beans are treated with steam in order to draw the caffeine from the inner bean to the outer surface area. Once this has been done, the solvent (Methylene Chloride) is applied directly to the beans, removing the caffeine. Steam is again applied to the coffee, driving out residual solvent. Then the beans are dried and roasted just like any other green coffee.


Why is this method supposed to be so good?

Methylene Chloride is a selective solvent, removing only the caffeine and wax from the beans, leaving the coffees flavour intact.


Does any of the chemical remain on the bean after the decaffeination process is complete?

Minute traces. Methylene chloride evaporates at 100 to 200°F; beans are usually roasted at a temperature of 350 to 425°F and coffee is brewed at 190 to 212°F. Any amounts of methylene chloride left in brewed coffee would be less than one part per million.


Does methylene chloride cause cancer in laboratory animals?

According to a report published by the American Medical Association in August 1985, studies of rats fed regular and decaffeinated coffee (at doses equivalent to 70 or 80 cups of coffee per day) or fed methylene chloride in their drinking water (at doses equivalent to 125,000 to 625,000 cups of decaffeinated coffee per day) showed no evidence of carcinogenicity… Hence scientific evidence suggests that methylene chloride is safe for use as a solvent for decaffeinating coffee.


Is methylene chloride also used in paint removers and hair sprays?

According to Dr Samuel Lee, methylene chloride belongs to an important family of chemical compounds with widespread uses, called halogenated hydrocarbons. It is prepared by the chlorination of methane, the major component of natural gas. Methane is a compound of a single carbon atom with four hydrogens, each replaceable by chlorine.

How you replace the hydrogens with chlorine determines what your end result will be. When all four of the hydrogens are displaced, you get a heavy liquid that can be used as a dry cleaning solvent, spot remover, and as a fire extinguisher.

When three of the hydrogens are replaced by chlorine, the result is chloroform, used for over a century as the anaesthetic in surgical operations.

When only two of the hydrogens are replaced by chlorine, the result is methylene chloride, and when only one chlorine is included we get methyl chloride (used by doctors and dentists as a local anaesthetic).


If the process is non-toxic, inexpensive and the decaffeinated coffee tastes good, why are consumers so wary of it?

The dreaded ‘C’ word – exaggerated reports of suspected carcinogenicity. UK and American roasters agree that the process is safe, inexpensive and produces a great tasting cup of decaffeinated coffee. They also agree that MC decaffeination will eventually cease. Not because it is harmful, but because of the public’s perception that it is harmful.


The best thing to do is make up your own mind. If you are the type that doesn’t take aspirin, eat white sugar, has low cholesterol and exercises every day, you probably won’t want to take the one in several million chance that you may develop cancer as a result of drinking coffee decaffeinated with methylene chloride. If you are like me, and want to be able to drink a great tasting cup of decaffeinated coffee occasionally, then keep an open mind about it and give the coffee a try.


This article is a reproduction from Coffee and Cocoa International Magazine circa 1988 and is the best description we have found of this process.


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