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Since the excessive consumption of caffeine can cause anxiety, abdominal pain and insomnia, many coffee enthusiasts have decided or have been advised to drink only decaffeinated coffee. So, just how is caffeine removed from coffee?
Decaffeinating methods vary, but most use chemical solvents to strip most of the caffeine from the coffee beans while they are still green. These methods of removing caffeine from coffee involve either direct contact with the decaffeinating agent or indirect contact.
Common methods of extracting caffeine from coffee
There are four basic methods of extracting caffeine from coffee. These methods include the use of solvents, like methelyene chloride and ethyl acetate or substances, like liquid carbon dioxide or water. All four methods share some common steps in the basic stages of the decaffeinating process.
- The green coffee beans are soaked in water or steamed to cause them to swell and make the caffeine available for extraction.
- The caffeine is actually extracted from the coffee beans.
- The coffee beans are steamed to strip any solvent residues (if solvents are used).
- The decaffeinated coffee beans are dried back to their original moisture content.
Extracting caffeine using the methelyene chloride process
The solvent, methelyene chloride, is used both as a direct contact method and an indirect method of caffeine extraction.
In the direct contact method, the softened coffee beans are repeatedly rinsed in methelyene chloride for several hours, which removes the caffeine from the beans. The caffeine-laden solvent is then drained away and the coffee beans are steamed to allow any remaining solvent to evaporate.
In the indirect contact method, after the coffee beans are soaked in near boiling water, the water containing the flavor oils and caffeine from the coffee is separated into a tank and treated with the solvent.
Removing caffeine from coffee using the ethyl acetate method
This process is very similar to the indirect contact method using methelyene chloride, except for the fact that ethyl acetate requires more time to absorb the caffeine.
The caffeine extraction process using ethyl acetate is repeated several times, until the residual caffeine level meets the legal maximum level. Coffee decaffeinated using this solvent is commonly referred to as natural decaf, since ethyl acetate is derived from fruits.
Decaffeinating coffee using the liquid carbon dioxide process
This process of extracting caffeine is simple and is normally conducted in large-scale decaf coffee production for economic reasons. The carbon dioxide is forced through the green coffee beans, which allows it to penetrate the coffee beans and actually dissolves most of the caffeine present.
Removing caffeine using the water method
There are two methods of caffeine extraction using only water and charcoal or carbon filters to remove the caffeine. No chemical solvents are used in either process and the only difference between these two processes seems to be the source of the water.
One water method is known as the "Swiss Water Process", developed by Swiss Water Decaffeinated Coffee Company, Inc of Canada and the other is known as "Mountain Water Decaffeination Process", developed by a company in Mexico.
In this process, the green coffee beans are soaked in hot water to draw off the caffeine, and then this resulting solution of caffeine and flavors is separated from the beans and sent through a bed of activated charcoal or carbon filters to remove the caffeine.
Caffeine appears to be a very valuable commodity, since most coffee companies recover the caffeine that has been extracted and sell it for use in soft drinks and prescription medications.
So, is your decaf really caffeine free?
It is important to understand that no matter which decaffeination process is used, neither process removes all of the caffeine from the coffee beans. A study conducted by the Mayo Clinic found that an eight ounce cup of regular generic brewed coffee contains from 95 mg to 200 mg of caffeine, while the same size cup of regular generic brewed decaffeinated coffee contains from 2 mg to 12 mg of caffeine.
According to research conducted at the University of Florida, drinking five or more cups of decaffeinated coffee would contain as much caffeine as one or two cups of regular caffeinated coffee.
If you love coffee and have decided to switch to decaf, please remember, even though the decaffeination process removes most of the caffeine, just because a coffee is labeled decaffeinated, it does not mean that the coffee is totally caffeine-free.
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