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decaffeination
Decaffeination is the act of removingcaffeine fromcoffeebeans,mate,cocoa,tea leaves and other caffeine containing materials. (While caffeine-free soft drinks are occasionally referred to as"decaffeinated," some are actually prepared by simply leaving caffeine out in the first place.)
In the case of coffee, the decaffeination processes are performed on unroasted (green) beans, but the methods vary somewhat.It generally starts with the steaming of the beans. They are then rinsed insolvent thatcontains as much of the chemical composition of coffee as possible without also containing the caffeine in a soluble form. Theprocess is repeated anywhere from 8 to 12 times until it meets either the international standard of having removed 97% of thecaffeine in the beans or theEU 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 physicalprocess or chemical reaction will remove only caffeine while leaving the other chemicals at their original concentrations.
Coffea arabica normally contains about half the caffeine ofCoffea robusta. A Coffea arabica bean containing little caffeine has been found recentlyin Ethiopia.[1] This may change how low-caffeine coffee isproduced 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.
Roselius process
The first commercially successful decaffeination process was invented byLudwigRoselius and Karl Wimmer in 1903. It involved steaming coffee beans with abrine (salt water) solution and then usingbenzene as a solventto remove the caffeine. Coffee decaffeinated this way was sold as Cafe sanka inFrance andlater asSanka brand coffee in theUS. Due to healthconcerns regarding benzene, this process is no longer used commercially and Sanka is produced using a different process.
Swiss water process
The Swiss Water Process is a method of decaffeinatingcoffee beans that was developed by theSwiss Water Decaffeinated Coffee Company. To decaffeinate the coffee bean by the Swiss Water method, a batch of green(unroasted) beans is soaked in hot water, releasingcaffeine. This process is done for a while,until all the caffeine and coffee solids are released into the water. These beans are then discarded. Next, the water passesthrough a carbon filter which traps the caffeine molecules but allows the water and the coffee solids to pass through. Thecaffeine-free water which comes through, known as "flavor-charged" water by the company, is then put in a similar filtrationdevice, and new coffee beans are added. However, since the flavor-charged water cannot remove any of the coffee solids from thenew beans, only the caffeine is released. The process repeats, filtering out all the caffeine until the beans are 99.9% caffeinefree. These beans are removed and dried, and thus retain most if not all of their flavor and smell.
Although the process originated in Switzerland in the 1930s, today the world‘s only Swiss Water decaffeination facility isbased nearVancouver,Canada[2].
Direct method
In the direct method the coffee beans are first steamed for 30 minutes and then repeatedly rinsed with eithermethylene chloride orethyl acetatefor about 10 hours. Thesolvent is then drained away and the beans steamed for an additional 10hours to remove any residual solvent. Sometimes coffeesdecaffeinated using ethyl acetate are referred to as naturallyprocessed because ethyl acetate can be derived from various fruitsor vegetables. However for the purpose of decaffeination it is notgenerally possible to create such a large quantity of ethylacetate, thus the chemical is synthetically derived.
Indirect method
In the indirect method beans are first soaked in hot water for several hours, essentially making a strong pot of coffee. Thenthe beans are removed and either methylene chloride or ethyl acetate is used to extract the caffeine from the water—as in othermethods, the caffeine can then be separated from the organic solvent by simple evaporation. The same water is recycled throughthis two-step process with new batches of beans. Anequilibriumis reached afterseveral cycles, where the water and the beans have a similarcomposition except for the caffeine. After this point, the caffeineis the only material removed from the beans, so no coffee strength orother flavorings are lost. Because water is used in theinitial phase of this process, sometimes indirect method decaffeinationis referred to as "water processed" even though chemicalsare used.
CO2/O2 process
With the CO2 process, pre-steamed beans are soaked in a liquid bath ofcarbondioxide at 73 to 300 atmospheres. After a thorough soaking, the pressure is reduced allowing the CO2 toevaporate, or the pressurized CO2 is run through either water orcharcoal filters toremove the caffeine. The carbon dioxide is then used on another batch of beans. This same process can also be done withoxygen (O2). These liquids work better than water because they are kept insupercritical state near the transition from liquid to gas so that they have thehigh diffusion of gas and the high density of a liquid.
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 beansare 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 todecaffeinate another batch of beans. This is a direct contact method of decaffeination.
Decaffeinated tea
Tea may also be decaffeinated, usually by using processes analagous to the Direct Method or the CO2 process asdescribed above. Fermentation (i.e. the process of oxidizing tea leaves to create "black," "red," or "oolong" tea leaves fromgreen leaves) does not affect the amount of caffeine present in the tea, though tea plant species (i.e. Camellia sinensissinensis vs. Camellia sinensis assamica) may differ in natural caffeine content. Younger leaves and buds contain morecaffeine per weight than older leaves and stems. A generally accepted statistic is that a cup of tea contains 40-50 mg ofcaffeine, roughly half the content of a cup of coffee.[3]Tea can be decaffeinated by 90% (+- 8% depending on the tea) by ‘rinsing‘ the tea for 30 second in boiling water before brewing,usually with very little degradation in flavor.
Caffeine content of decaffeinated coffee
Almost all brands of decaffeinated coffee still contain some caffeine.[4] Drinking ten cups of decaffeinated coffee could deliver as much caffeine as one or two cups ofregular coffee, according to research at the University of Florida Maples Center for Forensic Medicine.[citation needed] However, a new study undertaken in June 2004 has revealedthat a naturally caffeine-free bean has been produced.[5]
References
^ "Scientists discover decaf coffee bean", Guardian Unlimited, June 24, 2004.
^History of the SWISS WATER® Decaffeination Process , Jan 04, 2007
^ Upton Tea Imports (2003). "Tea and Caffeine". Upoton Tea Imports Newsletter 16 (1). Retrieved on 2007/01/26.
^"Study: Decaf coffee is not caffeine-free" UPI, October 10, 2006, at ScienceDaily.com. viewed 10/10/2006
^"Naturally decaffeinated coffee plant discovered", NewScientist.com, June 23, 2004
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 varieties:List of varieties |Coffea arabica:Kenya AA,Kona,Jamaican Blue Mountain |Coffea canephora (robusta):Kopi Luwak
Major chemicals in coffee:Caffeine |Cafestol
Coffee beanprocessing:Coffee roasting |Home roasting coffee | Decaffeination
Common beveragepreparation:Espresso (lungo,ristretto) |Drip brew (fromcoffeemakers) |French press |
Turkish coffee |Instant coffee |Chemex |Moka Express
Popular coffee beverages:Americano/Long black |Café au lait/Café con leche |Cafe mocha |Ca phe sua da
Cappuccino |Greek frappé coffee |Irish coffee |Latte/Flat white | Macchiato (espresso,latte) |Iced coffee |Red eye
Coffee and lifestyle:Social aspects of coffee |Coffeehouse |Caffè |Café |Caffè sospeso |Coffee cupping