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By Tracy Howard
Decaf coffee has always suffered a bit of an image problem, and when you stop to think about how a coffee bean could have one of its primary elements stripped away and still taste good, it’s no wonder that stigma has stuck. So what exactly is the magic process behind removing caffeine from coffee? Here’s a quick rundown of the three main decaffeination methods.
Chemical processing is typically handled either directly or indirectly using methylene chloride or ethyl acetate, which is a naturally occurring compound found in a variety of fruits. In the indirect method, green coffee beans are soaked in hot water, which separates the caffeine, as well as the flavor oils, from the beans. The water is transferred to a tank where it is treated with one of the two chemicals. The chemical then bonds with the caffeine in the water, making it easier to separate. After filtering out the caffeine, the beans are then reintroduced to the water in order to reabsorb their flavor and oils. In the direct method, the beans are steamed and then rinsed with either methylene chloride or ethyl acetate to remove the caffeine. The beans are then steamed again to remove any chemical residue.
Water processing occurs in two ways: the trademarked Mountain Water and Swiss Water processes. Mountain Water processing takes place in Mexico while the Swiss Water process, which originated in a small Swiss plant in the 1930s, today takes place at a single facility near Vancouver, British Columbia, using water from Canadian coastal mountains. Generally, the two water processes involve similar steps, beginning with green coffee beans being either steamed or soaked in hot water to expand the coffee’s pores, making the caffeine more easily extractable. From there, the beans are soaked in water and a proprietary blend of coffee solids, which, over time removes the caffeine while leaving the original flavor oils intact. That water is then moved to a separate tank and the caffeine is filtered out. The beans are dried and shipped to roasters around the world.
Carbon Dioxide Processing
In the carbon dioxide decaffeination method, green coffee beans are soaked in water in a large stainless steel tank, and pressurized carbon dioxide is introduced to the water. The caffeine molecules are attracted to the CO2, while the coffee’s proteins and carbohydrates stay intact. The caffeine-charged CO2 is then transferred to another stainless steel tank where the pressure is released, returning the CO2 to its gaseous state and leaving the caffeine behind. The caffeine-free beans are then dried, and the CO2 is reserved for the next cycle of decaffeination.
To see our Taste Test of seven different decaffeinated coffees, check out the January/February 2010 issue.