Decaffeination is the removal of
caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
from
coffee beans
A coffee bean is a seed of the ''Coffea'' plant and the source for coffee. It is the pip inside the red or purple fruit often referred to as a coffee cherry. Just like ordinary cherries, the coffee fruit is also a so-called stone fruit. Even thou ...
,
cocoa
Cocoa may refer to:
Chocolate
* Chocolate
* ''Theobroma cacao'', the cocoa tree
* Cocoa bean, seed of ''Theobroma cacao''
* Chocolate liquor, or cocoa liquor, pure, liquid chocolate extracted from the cocoa bean, including both cocoa butter and ...
,
tea
Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of southwestern China and northe ...
leaves, and other caffeine-containing materials. Decaffeinated drinks contain typically 1–2% of the original caffeine content, and sometimes as much as 20%.
Decaffeinated products are commonly termed decaf.
Decaffeination of coffee
Friedlieb Ferdinand Runge
Friedlieb Ferdinand Runge (8 February 1794 – 25 March 1867) was a German analytical chemist. Runge identified the mydriatic (pupil dilating) effects of belladonna (deadly nightshade) extract, identified caffeine, and discovered the first coal ...
performed the first isolation of pure caffeine from coffee beans in 1820, after the poet
Goethe
Johann Wolfgang von Goethe (28 August 1749 – 22 March 1832) was a German poet, playwright, novelist, scientist, statesman, theatre director, and critic. His works include plays, poetry, literature, and aesthetic criticism, as well as treat ...
heard about his work on
belladonna extract, and requested he perform an analysis on coffee beans. Though Runge was able to isolate the compound, he did not learn much about the chemistry of caffeine itself, nor did he seek to use the process commercially to produce decaffeinated coffee.
Decaffeination processes
Various methods can be used for decaffeination of coffee. These methods take place prior to roasting and may use organic solvents such as
dichloromethane
Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...
or
ethyl acetate
Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues ...
,
supercritical CO2, or water to extract caffeine from the beans, while leaving flavour precursors in as close to their original state as possible.
Organic solvent processes
=Direct method
=
The first commercially successful decaffeination process was invented by German merchant
Ludwig Roselius
Ludwig Roselius (2 June 1874 – 15 May 1943) 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. As a patron, he supported arti ...
and co-workers in 1903, after Roselius observed that a consignment of coffee beans accidentally soaked in sea water had lost most of their caffeine content without losing much of their flavour.
The process was patented in 1906, and involved steaming coffee beans with various
acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...
s or
bases, then using
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
as a solvent to remove the caffeine. Coffee decaffeinated this way was sold as
Kaffee HAG after the company name ''Kaffee Handels-Aktien-Gesellschaft'' (Coffee Trading Company) in most of Europe, as ''Café Sanka'' in
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
and later as
Sanka
Sanka is a brand of instant decaffeinated coffee, sold around the world, and was one of the earliest decaffeinated varieties. Sanka is distributed in the United States by Kraft Heinz.
History
Decaffeinated coffee was developed in 1903 by a team ...
brand coffee in the
US.
Café HAG
Café HAG is a worldwide brand of decaffeinated coffee currently owned by JDE Peet's.
History
Café HAG was founded in Bremen in 1906 as ''Kaffee-Handels-Aktiengesellschaft'' (Coffee Trading Limited). The company's founder was Ludwig Roseliu ...
and Sanka are now worldwide brands of
Kraft Foods
The second incarnation of Kraft Foods is an American food manufacturing and processing conglomerate, split from Kraft Foods Inc. in 2012 and headquartered in Chicago, Illinois. It became part of Kraft Heinz in 2015.
A merger with Heinz, arra ...
.
![Kaffee hag newspaper ad](https://upload.wikimedia.org/wikipedia/commons/7/76/Kaffee_hag_newspaper_ad.png)
Methods similar to those first developed by Roselius have continued to dominate, and are sometimes known as the ''direct organic solvent method''. However, because of health concerns regarding benzene (which is recognized today as a
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
),
other solvents, such as
dichloromethane
Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...
or
ethyl acetate
Ethyl acetate ( systematically ethyl ethanoate, commonly abbreviated EtOAc, ETAC or EA) is the organic compound with the formula , simplified to . This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues ...
, are now used. The not roasted (green) beans are first steamed and then rinsed with the solvent which extracts the caffeine, while leaving other constituents largely unaffected. The process is repeated from 8 to 12 times until the caffeine content meets the required standard (97% of caffeine removed according to the US standard, or 99.9% caffeine-free by mass per the EU standard).
=Indirect method
=
Another variation of Roselius' method is the ''indirect organic solvent method''. In this method, instead of treating the beans directly, they are first soaked in hot water for several hours, then removed. The remaining water is treated with solvents (e.g. dichloromethane or ethyl acetate) 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, wherein 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, indirect method decaffeination is sometimes referred to as "water-processed". This method was first mentioned in 1941, and people have made great efforts to make the process more "natural" and a true water-based process by finding ways to process the caffeine out of the water in ways that circumvents the use of organic solvents.
Swiss Water process
![Green Decaffeinated Brazilian Coffee Sack](https://upload.wikimedia.org/wikipedia/commons/d/d2/Green_Decaffeinated_Brazilian_Coffee_Sack.JPG)
An alternative method for removal of caffeine from coffee is the Swiss Water process. This process uses no organic solvents, and instead only water is used to decaffeinate beans, a technique first developed in Switzerland in 1933, and commercialized by Coffex S.A. in 1980.
The Swiss Water process was then introduced by The Swiss Water Decaffeinated Coffee Company of
Burnaby
Burnaby is a city in the Lower Mainland region of British Columbia, Canada. Located in the centre of the Burrard Peninsula, it neighbours the City of Vancouver to the west, the District of North Vancouver across the confluence of the Burrard I ...
,
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
, Canada, in 1988.
The process uses
green coffee extract
Green coffee extract is an extract of unroasted, green coffee beans. It is used in the Swiss water process for decaffeinating coffee. It has also been used as a weight-loss supplement and as an ingredient in other weight-loss products, although ...
(GCE) for the caffeine extraction mechanism. Green coffee extract is a solution containing the water-soluble components of green coffee except for the caffeine, obtained by soaking green coffee beans in hot water, then filtering through an activated charcoal filter to remove the caffeine molecules.
Fresh beans containing both caffeine and the other components are added to the GCE solution, where the gradient pressure difference between the GCE (which is caffeine-lean) and the green coffee (which is caffeine-rich) causes the caffeine molecules to migrate from the green coffee into the GCE. Because GCE is saturated with the other water-soluble components of green coffee, only the caffeine molecule migrates to the GCE; the other water-soluble coffee elements are retained in the green coffee. The newly caffeine-rich GCE solution is then passed through the
activated carbon
Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area avail ...
filters to remove the caffeine again, and the process is repeated. The continuous batch process takes 8–10 hours to meet the final residual decaffeinated target.
Noted food engineer
Torunn Atteraas Garin
Torunn Atteraas Garin (1947/1948 - 2 May 2002) was a Norwegian chemical engineer who worked on notable food projects. She worked on the artificial sweetener aspartame and was a national spokesperson for the product. She also developed nontoxic proc ...
also developed a process to remove caffeine from coffee.
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 and left to soak.
After several hours of high temperatures, the
triglycerides
A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride'').
Triglycerides are the main constituents of body fat in humans and other vertebrates, as we ...
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.
Supercritical CO2 process
Food scientists have also turned to
supercritical carbon dioxide
Supercritical carbon dioxide (s) is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure.
Carbon dioxide usually behaves as a gas in air at standard temperature and pressure (STP), or as ...
(sCO
2) as a means of decaffeination. Developed by Kurt Zosel, a scientist of the Max Planck Institute, it uses CO
2 (carbon dioxide), heated and pressurised above its
critical point, to extract caffeine.
Green coffee beans are steamed and then added to a high pressure vessel. A mixture of water and CO
2 is circulated through the vessel at 300
atm and . At this pressure and temperature CO
2 is a
supercritical fluid
A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous so ...
, with properties midway between a gas and a liquid. Caffeine dissolves into the CO
2; but compounds contributing to the flavour of the brewed coffee are largely insoluble in CO
2 and remain in the bean. In a separate vessel, caffeine is scrubbed from the CO
2 with additional water. The CO
2 is then recirculated to the pressure vessel.
Caffeine content of coffee
Caffeine content of decaffeinated coffee
To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low. A caffeine content reduction of at least 97% is required under United States standards. There is less than 0.1% caffeine in decaffeinated coffee and less than 0.3% in decaffeinated instant coffee in Canada. Many coffee companies use
high-performance liquid chromatography
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
(HPLC) to measure how much caffeine remains in the coffee beans. However, since HPLC can be quite costly, some coffee companies are beginning to use other methods such as
near-infrared (NIR) spectroscopy. Although HPLC is highly accurate, NIR spectroscopy is much faster, cheaper and overall easier to use. Lastly, another method typically used to measure the remaining caffeine includes
ultraviolet–visible spectroscopy
UV spectroscopy or UV–visible spectrophotometry (UV–Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in part of the ultraviolet and the full, adjacent visible regions of the electromagnetic spectrum. Being relativel ...
: useful for decaffeination processes that include supercritical CO
2, as CO
2 does not absorb in the UV-Vis range.
A controlled study in 2006 at
Florida State University
Florida State University (FSU) is a public research university in Tallahassee, Florida. It is a senior member of the State University System of Florida. Founded in 1851, it is located on the oldest continuous site of higher education in the st ...
of ten samples of prepared decaffeinated coffee from coffee shops showed that some caffeine remained.
Fourteen to twenty cups of such decaffeinated coffee would contain as much caffeine as one cup of regular coffee.
The 473 ml (16 ounce) cups of coffee samples contained caffeine in the range of 8.6 mg to 13.9 mg. In another study of popular brands of decaf coffees, the caffeine content varied from 3 mg to 32 mg. In contrast, a 237 ml (8 ounce) cup of regular coffee contains 95–200 mg of caffeine, and a 355 ml (12 ounce) serving of
Coca-Cola
Coca-Cola, or Coke, is a carbonated soft drink manufactured by the Coca-Cola Company. Originally marketed as a temperance drink and intended as a patent medicine, it was invented in the late 19th century by John Stith Pemberton in Atlanta ...
contains 36 mg.
Both of these studies tested the caffeine content of store-brewed coffee, suggesting that the caffeine may be residual from the normal coffee served rather than poorly decaffeinated coffee.
Decaffito
As of 2009, progress toward growing coffee beans that do not contain caffeine was still continuing. The term "Decaffito" has been coined to describe this type of coffee, and trademarked in Brazil.
The prospect for Decaffito-type coffees was shown by the discovery of the naturally caffeine-free ''
Coffea charrieriana
''Coffea charrieriana'', also known as Charrier coffee, is a species of flowering plant from the ''Coffea'' genus. It is a caffeine-free coffee plant endemic to Cameroon in Central Africa. It is the first recorded caffeine-free ''Coffea'' in Cent ...
'' variety, reported in 2004. It has a deficient
caffeine synthase gene, leading it to accumulate
theobromine
Theobromine, also known as xantheose, is the principal alkaloid of ''Theobroma cacao'' (cacao plant). Theobromine is slightly water-soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to s ...
instead of converting it to caffeine.
Either this trait could be bred into other coffee plants by crossing them with ''C. charrieriana'', or an equivalent effect could be achieved by
knocking out
A knockout (abbreviated to KO or K.O.) is a fight-ending, winning criterion in several full-contact combat sports, such as boxing, kickboxing, muay thai, mixed martial arts, karate, some forms of taekwondo and other sports involving striking ...
the gene for caffeine synthase in normal coffee plants.
Decaffeinated tea
Tea may also be decaffeinated, usually by using processes analogous to the direct method or the CO
2 process, as described above. Oxidizing tea leaves to create
black tea
Black tea, also translated to red tea in various East Asian languages, is a type of tea that is more oxidized than oolong, yellow, white and green teas. Black tea is generally stronger in flavour than other teas. All five types are made from ...
("red" in
Chinese tea
Tea is a beverage made from the leaves of tea plants ('' Camellia sinensis'') and boiled water. Tea leaves are processed using traditional Chinese methods. Chinese tea is consumed throughout the day, including during meals, as a substitute for ...
culture) or
oolong tea
Oolong (, ; (''wūlóngchá'', "dark dragon" tea)) is a traditional semi-oxidized Chinese tea (''Camellia sinensis)'' produced through a process including withering the plant under strong sun and oxidation before curling and twisting.Zhongguo ...
leaves from green leaves does not affect the amount of caffeine in the tea, though tea-plant subspecies (i.e. ''
Camellia sinensis sinensis'' vs. ''
Camellia sinensis assamica'') may differ in natural caffeine content. Younger leaves and buds contain more caffeine by weight than older leaves and stems. Although the CO
2 process is favorable because it is convenient, nonexplosive, and nontoxic, a comparison between regular and decaffeinated green teas using supercritical carbon dioxide showed that most volatile, non
polar compound
In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end.
Polar molecules must contain one or more pola ...
s (such as
linalool
Linalool () refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of ...
and
phenylacetaldehyde
Phenylacetaldehyde is an organic compound used in the synthesis of fragrances and polymers. Phenylacetaldehyde is an aldehyde that consists of acetaldehyde bearing a phenyl substituent; the parent member of the phenylacetaldehyde class of compound ...
), green and floral flavor compounds (such as
hexanal
Hexanal, also called hexanaldehyde or caproaldehyde is an alkyl aldehyde used in the flavor industry to produce fruity flavors. Its scent resembles freshly cut grass
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monoc ...
and (''E'')-2-
hexenal
''cis''-3-Hexenal, also known as (''Z'')-3-hexenal and leaf aldehyde, is an organic compound with the formula CH3CH2CH=CHCH2CHO. It is classified as an Saturated and unsaturated compounds, unsaturated aldehyde. It is a colorless liquid and an aro ...
), and some unknown compounds disappeared or decreased after decaffeination.
In addition to CO
2 process extraction, tea may be also decaffeinated using a hot water treatment. Optimal conditions are met by controlling water temperature, extraction time, and ratio of leaf to water. Temperatures of 100 °C or more, moderate extraction time of 3 minutes, and a 1:20 leaf to water weight per volume ratio removed 83% caffeine content and preserved 95% of total
catechins
Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of comp ...
. Catechins, a type of
flavanol
Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compo ...
, contribute to the flavor of the tea and have been shown to increase the suppression of
mutagen
In genetics, a mutagen is a physical or chemical agent that permanently changes nucleic acid, genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can ca ...
s that may lead to cancer.
Both coffee and tea have
tannins
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
The term ''tannin'' (from Anglo-Norman ''tanner'', f ...
, which are responsible for their
astringent
An astringent (sometimes called adstringent) is a chemical that shrinks or constricts body tissues. The word derives from the Latin ''adstringere'', which means "to bind fast". Calamine lotion, witch hazel, and yerba mansa, a Californian plant ...
taste, but tea has around one third of the tannin content of coffee. Thus, decaffeination of tea requires more care to maintain tannin content than decaffeination of coffee in order to preserve this flavor. Preserving tannins is desirable not only because of their flavor, but also because they have been shown to have anticarcinogenic, antimutagenic, antioxidative, and antimicrobial properties. Specifically, tannins accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, and modulate immunoresponses.
Certain processes during normal production might help to decrease the caffeine content directly, or simply lower the rate at which it is released throughout each infusion. In China, this is evident in many cooked
pu-erh tea
''Pu'er'' or ''pu-erh'' is a variety of fermented tea traditionally produced in Yunnan Province, China. In the context of traditional Chinese tea production terminology, fermentation refers to microbial fermentation (called 'wet piling'), and ...
s, as well as more heavily fired
Wuyi Mountain
The Wuyi Mountains or Wuyishan (; formerly known as Bohea Hills in early Western documents) are a mountain range located in the prefecture of Nanping, in northern Fujian province near the border with Jiangxi province, China. The highest peak i ...
oolongs; commonly referred to as 'zhonghuo' (mid-fired) or 'zuhuo' (high-fired).
A generally accepted statistic is that a cup of normal black (or red) 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 seconds) steep is believed to much reduce caffeine content of a subsequent brew at the cost of some loss of flavor, 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).
See also
*
Health effects of caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine to ...
*
Health effects of coffee
A 2017 umbrella review of meta-analyses found that drinking coffee is generally safe within usual levels of intake and is more likely to improve health outcomes than to cause harm at doses of 3 or 4 cups of coffee daily. Exceptions include possibl ...
*
Health effects of tea
Although health benefits have been assumed throughout the history of using ''Camellia sinensis'' as a common beverage, there is no high-quality evidence that consuming tea confers significant benefits other than possibly increasing alertness, an ...
*
Coffee substitute
Coffee substitutes are non-coffee products, usually without caffeine, that are used to imitate coffee. Coffee substitutes can be used for medical, economic and religious reasons, or simply because coffee is not readily available. Roasted grain b ...
References
{{Coffee, nocat=1
Chemical processes
Coffee production