Decaffeination is the act of removing
caffeineCaffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee, which in English became caffeine...
from
coffee beansCoffee is a brewed beverage prepared from roasted seeds, commonly called coffee beans, of the coffee plant. They are seeds of "coffee cherries" that grow on trees in over 70 countries. It has been said that green coffee is the second most traded commodity in the world behind crude oil. Due to its...
,
mateMate , also known as chimarrão or cimarrón, is a traditional South American infused drink. It is prepared from steeping dried leaves of yerba mate in hot water...
,
cocoaCocoa is the dried and fully fermented fatty seed of the cacao tree, from which chocolate is made. "Cocoa" can often also refer to the drink commonly known as hot chocolate; to cocoa powder, the dry powder made by grinding cocoa seeds and removing the cocoa butter from the dark, bitter cocoa...
,
teaTea is the agricultural product of the leaves, leaf buds, and internodes of the Camellia sinensis plant, prepared and cured by various methods...
leaves and other caffeine-containing materials. (While caffeine-free soft drinks are occasionally referred to as "decaffeinated," some are better termed "uncaffeinated": prepared via simply omitting caffeine from production.)
In the case of coffee, various methods can be used. The process is usually performed on unroasted (green) beans, and starts with steaming of the beans. They are then rinsed with a 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
EUThe European Union is an economic and political union of 27 Member States, located primarily in Europe. Committed to regional integration, the EU was established by the Treaty of Maastricht on 1 November 1993 upon the foundations of the pre-existing European Economic Community...
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; it is, therefore, challenging to remove only caffeine while leaving the other chemicals at their original concentrations.
Coffea arabicaCoffea arabica is a species of coffee indigenous to Ethiopia and Yemen. It is also known as the "coffee shrub of Arabia", "mountain coffee" or "arabica coffee". Coffea arabica is believed to be the first species of coffee to be cultivated, being grown in southwest Arabia for well over 1,000 years...
normally contains about half the caffeine of
Coffea robusta. A
Coffea arabica bean containing little caffeine was discovered in Ethiopia in 2004.
Roselius process
The first commercially successful decaffeination process was invented by
Ludwig RoseliusLudwig Roselius was a German coffee merchant and founder of the company KAFFEE HAG. He was born in Bremen and is credited with the development of commercial decaffeination of coffee...
and Karl Wimmer in 1903. It involved steaming coffee beans with a
brineBrine is water saturated or nearly saturated with a salt .It is used to preserve vegetables, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses.Brine is a common fluid used in large refrigeration installations for the transport of heat from...
(salt water) solution and then using
benzeneBenzene, or benzol, is an organic chemical compound with the molecular formula C6H6. It is sometimes abbreviated Ph–H. Benzene is a colorless and highly flammable liquid with a sweet smell and a relatively high melting point...
as a solvent to remove the caffeine. Coffee decaffeinated this way was sold as
Kaffee HAGCafé HAG is a worldwide brand of decaffeinated coffee owned by U.S. multinational Kraft Foods.The brand originated in Bremen in Germany in 1906 and took its name from the company title Kaffee Handels-Aktien-Gesellschaft, or Kaffee HAG for short....
after the company name
Kaffee Handels-Aktien-Gesellschaft (Coffee Trading Company) in most of Europe, as
Café Sanka in
FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
and later as
SankaSanka is a brand of decaffeinated coffee, sold around the world, and was one of the earliest decaffeinated varieties. Sanka is distributed in the United States by Kraft Foods.-History:...
brand coffee in the
U.SThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
Café HAGCafé HAG is a worldwide brand of decaffeinated coffee owned by U.S. multinational Kraft Foods.The brand originated in Bremen in Germany in 1906 and took its name from the company title Kaffee Handels-Aktien-Gesellschaft, or Kaffee HAG for short....
and Sanka are now worldwide brands of
Kraft FoodsKraft Foods, Inc. is the largest food and beverage company headquartered in the United States and the second largest in the world ....
. Due to health concerns regarding benzene, this process is no longer used commercially and Coffee Hag and Sanka are produced using a different process.
Swiss water process
The Swiss Water Process is a method of decaffeinating coffee beans developed by the Swiss 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, releasing
caffeineCaffeine is a bitter, white crystalline xanthine alkaloid that is a psychoactive stimulant drug. Caffeine was discovered by a German chemist, Friedrich Ferdinand Runge, in 1819. He coined the term kaffein, a chemical compound in coffee, which in English became caffeine...
. When all the caffeine and coffee solids are released into the water, the beans are discarded. The water then passes through a carbon filter that traps caffeine but lets the coffee solids pass through. The resulting solution, called "flavor-charged" water by the company, is then put in a similar filtration device, and new coffee beans are added. Since the flavor-charged water cannot remove any of the coffee solids from the new beans, only the caffeine is released. The process repeats, filtering out all the caffeine until the beans are 99.9% caffeine-free. These beans are removed and dried, and thus retain most if not all of their flavour and smell.
Although the process originated in Switzerland in the 1930s, today the world's only Swiss Water decaffeination facility is based near
VancouverVancouver is a coastal city and major seaport located in the Lower Mainland of southwestern British Columbia, Canada. The city is bounded by English Bay, Burrard Inlet, the Fraser River, the city of Burnaby, and the University Endowment Lands. Vancouver is named after Captain George Vancouver, a...
,
British ColumbiaBritish Columbia is the westernmost of Canada's provinces and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . In 1871, it became the sixth province of Canada.The capital of British Columbia is Victoria, the 15th largest metropolitan region in Canada...
,
CanadaCanada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean...
.
Direct method
In the direct method, the coffee beans are first steamed for 30 minutes and then repeatedly rinsed with either methylene chloride (Dichloromethane/DCM) or
ethyl acetateEthyl acetate is the organic compound with the formula CH3COOCH2CH3. This colorless liquid has a characteristic sweet smell like certain glues or nail polish removers, in which it is used...
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 that are decaffeinated using ethyl acetate are referred to as naturally processed because ethyl acetate can be derived from various fruits or vegetables; but, because of the impracticality of gathering natural ethyl acetate, the chemical used for decaffeination is synthetic.
Indirect method
In the indirect method, beans are first soaked in hot water for several hours, in essence, 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
equilibriumSolubility equilibrium is any type of chemical equilibrium relationship between solid and dissolved states of a compound at saturation.Solubility equilibria involve application of chemical principles and constants to predict solubility of substances under specific conditions .The substance that is...
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.
CO2 process
This process is technically known as
supercritical fluid extractionA supercritical fluid is any substance at a temperature and pressure above its critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. In addition, close to the critical point, small changes in pressure or temperature result in large changes in density,...
. Pre-steamed beans are soaked in a bath of supercritical
carbon dioxideCarbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state...
at a pressure of 73 to 300 atmospheres. After a thorough soaking, the pressure is reduced allowing the CO
2 to evaporate, or the pressurized CO
2 is run through either water or
charcoalCharcoal is the blackish residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood, sugar, bone char, or other substances in the absence of oxygen...
filters to remove the caffeine. The carbon dioxide is then used on another batch of beans. This liquid works better than water because it is kept in
supercriticalA supercritical fluid is any substance at a temperature and pressure above its critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. In addition, close to the critical point, small changes in pressure or temperature result in large changes in density,...
state near the transition from liquid to gas, combining favorable
diffusivityDiffusivity can refer to:*Diffusivity of heat*Diffusivity of mass:** Molecular diffusivity ** Eddy diffusivity*Momentum diffusivity...
properties of the gas with increased
densityVapour density is the density of a vapour in relation to that of hydrogen. It may be defined as mass of a certain volume of a substance divided by mass of same volume of hydrogen....
of a liquid. This process has the advantage that it avoids the use of potentially harmful solvents.
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.
Decaffeinated tea
Tea may also be decaffeinated, usually by using processes analogous to the Direct Method or the CO
2 process as described above. Fermentation (i.e., the process of oxidizing tea leaves to create "black," "white," or "oolong" tea leaves from green leaves) does not affect the amount of caffeine in the tea, though tea plant species (i.e.,
Camellia sinensis sinensis vs.
Camellia sinensis assamica) may differ in natural caffeine content. Younger leaves and buds contain more caffeine per weight than older leaves and stems. Also, certain processes during production might lend a hand in either decreasing the caffeine content directly or simply lowering the rate at which it is released throughout each infusion. Several instances in China where this is evident is in many cooked pu'er teas, as well as more heavily fired Wuyi Mountain oolongs; commonly referred to as 'zhonghuo' (mid-fired) or 'zuhuo' (high-fired). A generally accepted statistic is that a cup of tea contains 40–50 mg of caffeine, roughly half the content of a cup of coffee. Although a common technique of discarding a short (30– to 60-second) steep is believed to reduce caffeine content in a subsequent brew by 80–90%, research suggests that a five-minute steep yields up to 70% of the caffeine, and a second steep has one-third the caffeine of the first (about 23% of the total caffeine in the leaves).,
Caffeine content of decaffeinated coffee
Almost all brands of decaffeinated coffee still contain some caffeine. Drinking five to ten cups of decaffeinated coffee could deliver as much caffeine as would one or two cups of regular coffee, according to research at the University of Florida Maples Center for Forensic Medicine. In one independent research on 10 popular decaffeinated coffees, researchers found that all but one contained caffeine. The 16-ounce (473-milliliter) cups of coffee samples contained caffeine in the range of 8.6 milligrams to 13.9 milligrams. In another similar study of popular brands of decaf coffees, the caffeine content was anywhere from 3 milligrams up to 32 milligrams.
The need to remove caffeine could vanish if coffee growers begin using a naturally caffeine-free bean first produced in June 2004.