Decaffeination
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Decaffeination is the act of removing caffeine from coffee beans, mate, cocoa, tea leaves and other caffeine containing materials.
All decaffeination processes are performed on unroasted (green) coffee beans, but the methods vary somewhat. It generally starts with the steaming of the beans. They are then rinsed in solvent that contains as much of the chemical composition of coffee as possible without also containing the caffeine in a soluble form. The process is repeated anywhere from 8 to 12 times until it meets either the international standard of having removed 97% of the caffeine in the beans or the EU standard of having the beans 99.9% caffeine free by mass. Coffee contains over 400 chemicals important to the taste and aroma of the final drink; this effectively means that no chemical reaction will remove only caffeine while leaving the other chemicals at their original concentrations. While they are occasionally referred to informally as "decaffeinated," soft drinks without caffeine are prepared by simply leaving caffeine out in the first place.
Coffea arabica normally contains about half the caffeine of Coffea robusta. A Coffea arabica bean containing little caffeine has been found recently in Ethiopia.[1] This may change how low-caffeine coffee is produced in the future. Additionally, genetic engineering technology may be eventually applied to create a naturally caffeine-free coffee. But for now, one of several methods to remove the caffeine from caffeine-containing beans is employed.
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[edit] Roselius process
The first commercially successful decaffeination process was invented by Ludwig Roselius and Karl Wimmer in 1903. It involved steaming coffee beans with a brine (salt water) solution and then using benzene as a solvent to remove the caffeine. Coffee decaffeinated this way was sold as Cafe sanka in France and later as Sanka brand coffee in the US. Due to health concerns regarding benzene, this process is no longer used commercially and Sanka is produced using a different process.
[edit] Swiss Water Process
The Swiss Water Process uses only water to remove caffeine. Although the process originated in Switzerland in the 1930s, today the world's only Swiss Water decaffeination facility is based near Vancouver, Canada.
[edit] Direct method
In the direct method the coffee beans are first steamed for 30 minutes and then repeatedly rinsed with either methylene chloride or ethyl acetate for about 10 hours. The solvent is then drained away and the beans steamed for an additional 10 hours to remove any residual solvent. Sometimes, coffees decaffeinated using ethyl acetate are misleadingly referred to as "naturally processed" because ethyl acetate can be derived from various fruits or vegetables. However, for the purpose of decaffeination, it is not possible to create such a large quantity of ethyl acetate, thus the chemical is synthetically derived.
[edit] Indirect method
In the indirect method beans are first soaked in hot water for several hours, essentially making a strong pot of coffee. Then the beans are removed and either methylene chloride or ethyl acetate is used to extract the caffeine from the water—as in other methods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled through this two-step process with new batches of beans. An equilibrium is reached after several cycles, where the water and the beans have a similar composition except for the caffeine. After this point, the caffeine is the only material removed from the beans, so no coffee strength or other flavorings are lost. Because water is used in the initial phase of this process, sometimes indirect method decaffeination is referred to as "water processed" even though chemicals are used.
[edit] CO2/O2 process
With the CO2 process, pre-steamed beans are soaked in a liquid bath of carbon dioxide at 73 to 300 atmospheres. After a thorough soaking, the pressure is reduced allowing the CO2 to evaporate, or the pressurized CO2 is run through either water or charcoal filters to remove the caffeine. The carbon dioxide is then used on another batch of beans. This same process can also be done with oxygen (O2). These liquids work better than water because they are kept in supercritical state near the transition from liquid to gas so that they have the high diffusion of gas and the high density of a liquid.
[edit] Triglyceride process
Green coffee beans are soaked in a hot water/coffee solution to draw the caffeine to the surface of the beans. Next, the beans are transferred to another container and immersed in coffee oils that were obtained from spent coffee grounds.
After several hours of high temperatures, the triglycerides in the oils remove the caffeine - but not the flavor elements - from the beans. The beans are separated from the oils and dried. The caffeine is removed from the oils, which are reused to decaffeinate another batch of beans. This is a direct contact method of decaffeination.
[edit] Not caffeine free
Almost all brands of decaffeinated coffee still contain some caffeine. Drinking five to ten cups of decaf could deliver as much caffeine as one or two cups of regular coffee, according to research at the University of Florida Maples Center for Forensic Medicine. [2] [3]
[edit] References
- ^ "Scientists discover decaf coffee bean", Guardian Unlimited, June 24, 2004.
- ^ [1] "Study: Decaf coffee is not caffeine-free" UPI, October 10, 2006, at ScienceDaily.com. viewed 10/10/2006
- ^ Decaf coffee may still pack a mini-caffeine punch, CNN, October 23, 2006
- Ramalakshmi K., Raghavan B. (1999). "Caffeine in coffee: Its removal. Why and how?". Critical Rev. Food Sci. Nutrition 39: 441-456. DOI:10.1080/10408699991279231.
| Coffee |
| Facts about coffee: History of coffee | Economics of coffee | Coffee and health |
| Species and varietals: List of varietals | Coffea arabica: Kenya AA, Kona, Jamaican Blue Mountain | Coffea canephora (robusta): Kopi Luwak |
| Major chemicals in coffee: Caffeine | Cafestol |
| Coffee bean processing: Coffee roasting | Home roasting coffee | Decaffeination |
| Common beverage preparation: Espresso | Drip brew (from coffeemakers) | French press | Turkish coffee | Instant coffee | Chemex |
| Coffee and lifestyle: Social aspects of coffee | Coffeehouse | Caffé |
