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The Genesis of Decaffeinated Coffee© 2002 Brian Martell Caffeine is curious thing. It is a mild stimulant to the central nervous system when consumed in low does, by drinking coffee for example. In its pure form, it looks like a white powder with a slight bitter taste. It has helped many a student get through term papers, it jump starts the majority of Canadian adults to get their day going, and, yes, can be mildly addictive. Many studies have been conducted on the effects of caffeine, both good and bad, from the absurd (force-feeding rats the equivalent of 50 coffees a day) to the sublime (along with anabolic steroids, add caffeine to the list of banned substances complied by Dick Pound and the boys at the Olympic anti-doping centre). Most physicians will recommend that mothers-to-be should limit their coffee intake to no more than 3 cups a day as a preventative measure, but for the most part, coffee and its inherent caffeine is benign for most healthy adults. Why, then, do we even have decaffeinated coffee? There comes a time when the flavour and aroma of a good cup of coffee is seductive enough to make one over indulge (you know who you are); or the caffeine content adversely effects your ability to function properly. It’s at these times that coffee lovers who need to avoid the caffeine pay homage to Ludwig Roselius. Caffeine was first successfully isolated in 1821 as a pharmaceutical by-product of coffee. The effects of coffee were widely known for centuries before that as many a society had tried to either control or outright ban the consumption of coffee for it’s effects. Thus, by isolating the “active ingredient” in coffee, early scientists were able to better understand the effects of coffee on its consumers. From there, it was another 84 years in 1905 that Ludwig Roselius developed the first commercial method for decaffeinating coffee. Like all trail blazers, Roselius had a hard time marketing his new coffee. First, the new decaf was processed using benzene as the solvent, which performs less effectively than current solvents used in decaffeinating coffee. Second, the green beans were actually boiled before being exposed to the solvent, thus effectively removing almost all flavour components in the coffee. The preceding notwithstanding, the world was introduced to decaf and haven’t looked back since. Current methods of decaffeinating coffee still use some of the processes pioneered by Roselius, but with much better results. The commercial methods, varying in popularity and cost, used today are: Direct Method In the direct method, green coffee beans are steamed until soft for about 30 minutes and then rinsed in the solvent repeatedly for about 10 hours. The solvent captures the caffeine and is drained away from the green beans, which are then steamed for another 8 to 10 hours to evaporate the residual solvent. The decaffeinated beans are then air dried to their appropriate moisture level. Indirect Method, sometimes called the Water
Method In the indirect method, the green coffee beans are actually soaked in a hot water/coffee solution for several hours. Slowly, the solution removes the caffeine from the beans, as well as some of the desirable flavour elements of the coffee. The solution is then drained off and treated with the solvent, which absorbs the caffeine. The mixture is then heated to evaporate the solvent and caffeine leaving only the water/coffee solution. This caffeine free solution is then re-introduced to the green beans, allowing them to regain most of the flavour components lost during the soaking stage of the process. Methyl chloride is used as an effective solvent in the decaffeinating process in both the direct and indirect methods due to its excellent soluble properties. While methyl chloride does pose a health risk in high doses, the amount of this solvent present in the decaffeinated green bean weighs in at no more than one part per million. Further, methyl chloride evaporates at 170 degrees F, leaving virtually no trace of the solvent after the 400 + degree F roasting process. Ethyl acetate is commonly referred to as a natural solvent in the decaffeinating process as it is derived from various fruits and vegetables. Decaffeinated coffees processed with ethyl acetate are often called “Natural Decafs.” Triglyceride Method Triglycerides, found in coffee oils, are used as a solvent to remove caffeine in coffee beans. In this process, the beans are soaked in a water/coffee solution to bring the caffeine to the surface of the bean. Next, the beans are submersed in coffee oils for several hours at high temperature. The triglcyerides remove the caffeine, but not the flavour from the coffee beans. The beans are removed from the oils and dried. Once the caffeine has been removed from the oils, the oils are then recuperated for use in the next decaffeinating cycle. Swiss Water Method The Swiss Water method uses the same principle as the Indirect (Water) Method previously indicated. The main difference is that instead of using a solvent to remove the caffeine from the water, a series of charcoal or carbon filters are used to trap the caffeine. The re-introduction of the flavour components after the caffeine has been removed is the same for both the Indirect Method and the Swiss Water Process. Supercritical Carbon Dioxide/Oxygen By using special chambers, CO2 or Oxygen are transformed into a liquid state at 88 degrees F under tremendous pressure (73 atmospheres). The CO2 takes on the characteristics of both a liquid and a gas allowing for better penetration of the bean to dissolve the caffeine. Once the pressure is brought to near normal levels, the caffeine precipitates into another chamber and the green coffee is released. The CO2 or Oxygen is then ready to be re-pressurized for the next cycle. All the above methods will decaffeinate coffee to a level of at least 97% caffeine free, the level established by law where upon the coffee may be marketed as decaffeinated. By understanding the different methods of the decaffeinating process, we are better equipped to answer our customers questions on this, one of the lesser known areas of the coffee world.
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