Editing Decaffeination

{{Short description|Removal of caffeine}}
{{Redirect|Decaf|the computer software program|DECAF}}

'''Decaffeination''' is the removal of [[caffeine]] from [[coffee|coffee beans]], [[Cocoa bean|cocoa]], [[tea]] leaves, and other caffeine-containing materials. Decaffeinated products are commonly termed by the abbreviation '''decaf'''. 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 [[Food and Drug Administration|FDA]] standards.<ref>{{cite web |title=Decaffeinated Coffee |url=http://www.espressocoffeeguide.com/decaffeinated-coffee/ |website=www.espressocoffeeguide.com |date=11 May 2010 |access-date=2015-12-08}}</ref> A 2006 study found decaffeinated drinks to contain typically 1–2% of the original caffeine content, but sometimes as much as 20%.<ref name="sciencedaily"/> 

==Decaffeinated coffee==
[[Friedlieb Ferdinand Runge]] performed the first isolation of caffeine from coffee beans in 1820, after the German poet [[Goethe]] heard about his work on [[Atropa belladonna|belladonna]] extract, and requested he perform an analysis on coffee beans.<ref>{{cite book |title=The World of Caffeine: The Science and Culture of the World's Most Popular Drug |first1=Bennett Alan |last1=Weinberg |first2=Bonnie K. |last2=Bealer |publisher=Psychology Press |year=2001 |isbn=9780415927222 |url-access=registration |url=https://archive.org/details/worldofcaffeines00benn }}</ref> 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.{{citation needed|date=November 2024}}

===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]] or [[ethyl acetate]], [[supercritical carbon dioxide|supercritical CO<sub>2</sub>]], or water to extract caffeine from the beans, while leaving flavour precursors in as close to their original state as possible.<ref name="cafInCof">{{cite journal|last1=Ramalakshmi|first1=K.|last2=Raghavan|first2=B.|date=1999|title=Caffeine in Coffee: Its Removal. Why and How?|journal=Critical Reviews in Food Science and Nutrition|volume=39|issue=5|pages=441–56|doi=10.1080/10408699991279231|pmid=10516914}}</ref>

====Organic solvent====
=====Direct method=====
The first commercially successful decaffeination process was invented by German merchant [[Ludwig Roselius]] 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 while losing little of their flavour.<ref>{{cite web |url=https://illumin.usc.edu/204/where-does-my-decaf-come-from |url-status=dead |archive-url=https://web.archive.org/web/20120208025517/https://illumin.usc.edu/204/where-does-my-decaf-come-from |archive-date=2012-02-08 |title=Where Does My Decaf Come From? |website=Illumin |date=February 7, 2012}}</ref><ref name="decaf 101">{{cite web|last1=Emden|first1=Lorenzo|title=Decaffeination 101: Four Ways to Decaffeinate Coffee|url=http://www.coffeeconfidential.org/health/decaffeination/|website=Coffee Confidential|date=6 July 2012 |access-date=29 October 2014}}</ref> The process was patented in 1906, and involved steaming coffee beans with various [[acid]]s or [[Base (chemistry)|bases]], then using [[benzene]] as a solvent to remove the caffeine.<ref>{{US patent reference |number=897840 |y=1908 |m=09 |d=01 |inventor=Johann Friedrich Meyer Jr., Ludwig Roselius, Karl Heinrich Wimmer |title=Preparation of coffee}}</ref><ref>{{cite web |url=http://german.about.com/library/blerf_decaf.htm |title=Ludwig Roselius (1874–1943) |access-date=2012-08-20 |archive-date=2012-06-29 |archive-url=https://web.archive.org/web/20120629093928/http://german.about.com/library/blerf_decaf.htm |url-status=dead }}</ref> Coffee decaffeinated this way was sold as [[Café HAG|Kaffee HAG]] after the company name ''Kaffee Handels-Aktien-Gesellschaft'' (Coffee Trading Company) in most of Europe, as ''Café Sanka'' in [[France]] and later as [[Sanka]] brand coffee in the [[United States]]. [[Café HAG]] and Sanka are now worldwide brands of [[Kraft Foods]].{{citation needed|date=November 2024}}
[[File:Kaffee hag newspaper ad.png|thumb|1914 American newspaper advert for Kaffee HAG decaffeinated coffee]]
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]]),<ref name="IARC Monograph 100F">{{cite web|url=http://monographs.iarc.fr/ENG/Monographs/vol100F/mono100F.pdf|title=Chemical agents and related occupations, Volume 100F. A review of human carcinogens.|author=International Agency for Research on Cancer|publisher=International Agency for Research on Cancer|access-date=2014-08-20|archive-url=https://web.archive.org/web/20140821112721/http://monographs.iarc.fr/ENG/Monographs/vol100F/mono100F.pdf|archive-date=2014-08-21|url-status=dead}}</ref> other solvents, such as [[dichloromethane]] or [[ethyl acetate]], are now used.<ref>Ronald Clarke and O.O. Vizthum [https://books.google.com/books?hl=en&lr=&id=jIFY_Pz8LH0C&oi=fnd&pg=PR3&dq=Coffee:+Recent+developments ''Coffee: Recent Developments'']. Blackwell Science 2001, p. 109.</ref> The unroasted (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 between 8 and 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).<ref name="cafInCof" />

=====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 [[Solubility equilibrium|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.<ref>{{cite patent|country=US|number=4409253|title=Recovery of noncaffeine solubles in an extract decaffeination process|status=Patent|pubdate=1983-10-11|inventor-last=Morrison|inventor2-last=Elder|inventor3-last=John|inventor-first=Lowen|inventor2-first=Melisse|inventor3-first=Phillips}}</ref> 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 significant 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 circumvent the use of organic solvents.<ref>Ronald Clarke and O.O. Vizthum [https://books.google.com/books?hl=en&lr=&id=jIFY_Pz8LH0C&oi=fnd&pg=PR3&dq=Coffee:+Recent+developments ''Coffee: Recent Developments'']. Blackwell Science 2001, p. 111.</ref>

====Swiss Water====
[[File:Green Decaffeinated Brazilian Coffee Sack.JPG|thumb|Sack of green coffee beans decaffeinated by the Swiss Water process]]
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. It is a technique first developed in Switzerland in 1933, and commercialized by Coffex S.A. in 1980.<ref name="decaf 101" /> The Swiss Water process was then introduced by The Swiss Water Decaffeinated Coffee Company of [[Burnaby]], [[British Columbia]], in 1988.<ref>[http://www.swisswater.com/about/history History of the SWISS WATER Decaffeination Process] {{Webarchive|url=https://web.archive.org/web/20061230192710/http://www.swisswater.com/about/history |date=2006-12-30 }}, Jan 04, 2007</ref>

The process uses [[green coffee extract]] (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.<ref name="decaf 101" /> 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.<ref>{{Cite web|last=Dowling|first=Stephen|title=How do you decaffeinate coffee?|url=https://www.bbc.com/future/article/20180917-how-do-you-decaffeinate-coffee|access-date=2020-08-07|website=www.bbc.com|date=18 September 2018 |language=en}}</ref> Because GCE is saturated with the other water-soluble components of green coffee, only the caffeine molecules migrate 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]] 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.<ref name=":0">{{cite web|title=Extraction of Caffeine from Tea: Greening the Chemistry|url=https://web.archive.org/web/20160221223733/http://faculty.chemeketa.edu/jcammack/CH241-3B%20Lab/CH241B%20Labs/CH241%206%20Caffeine%20Extraction%20F14.pdf}}</ref>

Food engineer [[Torunn Atteraas Garin]] also developed a process to remove caffeine from coffee.<ref>{{cite news|title=Torunn A. Garin, 54, Noted Food Engineer|url=https://www.nytimes.com/2002/05/01/nyregion/torunn-a-garin-54-noted-food-engineer.html?_r=0|work=The New York Times|date=1 May 2002}}</ref><ref>{{Cite patent|country=US|number=4113887A|title=Adsorption process|status=|pubdate=|gdate=1977-02-24|invent1=Kramer|invent2=Henig|invent3=Garin|invent4=Vogel|inventor1-first=Franklin|inventor2-first=Yair Steve|inventor3-first=Torunn Atteraas|inventor4-first=Gerald James|inventorlink3=Torunn Atteraas Garin|url=https://patents.google.com/patent/US4113887A/en}}</ref>

====Triglyceride====
In this process, green coffee beans are soaked in a hot water and 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]] 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 CO<sub>2</sub>====
Food scientists have also turned to [[supercritical carbon dioxide]] (sCO<sub>2</sub>) as a means of decaffeination. Developed by Kurt Zosel, a scientist of the Max Planck Institute, it uses CO<sub>2</sub> (carbon dioxide), heated and pressurised above its [[critical point (thermodynamics)|critical point]], to extract caffeine.<ref name="decaf 101" /> Green coffee beans are steamed and then added to a high pressure vessel. A mixture of water and CO<sub>2</sub> is circulated through the vessel at 300 [[atmosphere (unit)|atm]] and {{cvt|65|°C}}. At this pressure and temperature CO<sub>2</sub> is a [[Supercritical carbon dioxide|supercritical fluid]], with properties midway between a gas and a liquid. Caffeine dissolves into the CO<sub>2</sub>; but compounds contributing to the flavour of the brewed coffee are largely insoluble in CO<sub>2</sub> and remain in the bean. In a separate vessel, caffeine is scrubbed from the CO<sub>2</sub> with additional water. The CO<sub>2</sub> is then recirculated to the pressure vessel.<ref name="cafInCof" /><ref>{{cite web|date=1 December 2013|title=How Do They Do It?: S7 E15 - Decaf Coffee; Smoked Salmon; Water Jets|url=https://www1.cartoonhd.nl/watch-show/how-do-they-do-it/season/7/episode/15|url-status=dead|archive-url=https://web.archive.org/web/20190401120303/https://www1.cartoonhd.nl/watch-show/how-do-they-do-it/season/7/episode/15|archive-date=1 April 2019|access-date=1 April 2019|publisher=[[How Do They Do It?]]}}</ref>

===Caffeine content of coffee===
{{main|Coffee#Caffeine content}}{{expand section|date=April 2022}}

===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.<ref>{{cite web |title=Decaffeinated Coffee |url=http://www.espressocoffeeguide.com/decaffeinated-coffee/ |website=www.espressocoffeeguide.com |date=11 May 2010 |access-date=2015-12-08}}</ref> There is less than 0.1% caffeine in decaffeinated coffee and less than 0.3% in decaffeinated instant coffee in Canada.<ref>{{Cite web|url=http://laws.justice.gc.ca/eng/regulations/C.R.C.,_c._870/page-35.html#h-67|title=Consolidated federal laws of canada, Food and Drug Regulations|last=Branch|first=Legislative Services|website=laws.justice.gc.ca|language=en|access-date=2018-07-19}}</ref> Many coffee companies use [[high-performance liquid chromatography]] (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 spectroscopy|near-infrared (NIR) spectroscopy]].<ref>{{cite web |url=http://www.camo.com/downloads/resources/application_notes/decaffeinated_coffee_NIR_spectroscopy.pdf |title=Determination of caffeine in decaffeinated coffee by NIR spectroscopy. |work=The Unscrambler |access-date=2015-12-08 |archive-url=https://web.archive.org/web/20160303205710/http://www.camo.com/downloads/resources/application_notes/decaffeinated_coffee_NIR_spectroscopy.pdf |archive-date=2016-03-03 |url-status=dead }}</ref> 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]]: useful for decaffeination processes that include supercritical CO<sub>2</sub>, as CO<sub>2</sub> does not absorb in the UV-Vis range.<ref>{{cite web |url=http://aai.solutions/documents/AA_AN019_Measuring-Caffeine-Concentration.pdf |title=Measuring Caffeine Concentration |work=Applied Analytics Application Note No. AN-019}}</ref>

A controlled study in 2006 at [[Florida State University]] consisting of ten samples of prepared decaffeinated coffee from coffee shops showed that some caffeine remained.<ref name="sciencedaily">{{cite journal |url=https://www.sciencedaily.com/releases/2006/10/061012185602.htm |title=Study: Decaf coffee is not caffeine-free |date=October 15, 2006 |access-date=2008-01-12 |doi=10.1093/jat/30.8.611|pmid=17132260 |last1=McCusker |first1=R. R. |last2=Fuehrlein |first2=B. |last3=Goldberger |first3=B. A. |last4=Gold |first4=M. S. |last5=Cone |first5=E. J. |journal=Journal of Analytical Toxicology |volume=30 |issue=8 |pages=611–613 |url-access=subscription }}</ref> Fourteen to twenty cups of such decaffeinated coffee would contain as much caffeine as one cup of regular coffee.<ref name="sciencedaily" /> The 473 ml (16 ounce) cups of coffee samples contained caffeine in the range of 8.6&nbsp;mg to 13.9&nbsp;mg. In another study of popular brands of decaf coffees, the caffeine content varied from 3&nbsp;mg to 32&nbsp;mg.<ref>[http://www.myproductalert.com/decaf-coffee.html "Are You Really Getting Caffeine-Free Decaf Coffee?"] {{Webarchive|url=https://web.archive.org/web/20080527222533/http://www.myproductalert.com/decaf-coffee.html |date=2008-05-27 }} Independent research on 10 popular decaffeinated coffees. Viewed Aug 05, 2008</ref> In contrast, a 237 ml (8 ounce) cup of regular coffee contains 95–200&nbsp;mg of caffeine,<ref>[http://www.mayoclinic.com/health/caffeine/AN01211 "Caffeine Content for Coffee, Tea, Soda, and More"] List of caffeine content in beverages known to contain caffeine. Viewed Aug 28, 2012</ref> and a 355 ml (12 ounce) serving of [[Coca-Cola]] contains 36&nbsp;mg.<ref>[http://www.caffeineinformer.com/caffeine-amounts-in-soda-every-kind-of-cola-you-can-think-of "Caffeine Amounts in Soda: Every Kind of Cola You Can Think Of"] List of caffeine content in popular soft drinks. Viewed Aug 28, 2012</ref>

==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.<ref name="decaffito">{{cite journal |author1=Paulo Mazzafera |author2=Thomas W. Baumann |author3=Milton Massao Shimizu |author4=Maria Bernadete Silvarolla |title=Decaf and the Steeplechase Towards Decaffito—the Coffee from Caffeine-Free Arabica Plants |journal=Tropical Plant Biology |volume=2 |issue=2 |pages=63–76 |date=June 2009 |doi=10.1007/s12042-009-9032-7 |s2cid=36008460 }}</ref>

The prospect for Decaffito-type coffees was shown by the discovery of the naturally caffeine-free ''[[Coffea charrieriana]]'' variety, reported in 2004. It has a deficient [[caffeine synthase]] gene, leading it to accumulate [[theobromine]] instead of converting it to caffeine.<ref name="pmid15215853">{{cite journal |vauthors=Silvarolla MB, Mazzafera P, Fazuoli LC |title=Plant biochemistry: a naturally decaffeinated arabica coffee |journal=Nature |volume=429 |issue=6994 |pages=826 |date=June 2004 |pmid=15215853 |doi=10.1038/429826a |bibcode=2004Natur.429..826S |s2cid=4428420 |doi-access=free }}</ref> Either this trait could be bred into other coffee plants by crossing them with ''C. charrieriana'', or an equivalent effect could be achieved by [[gene knockout|knocking out]] the gene for caffeine synthase in normal coffee plants.<ref>{{cite news |url=https://www.newscientist.com/article/dn6064-naturally-decaffeinated-coffee-plant-discovered/ |title=Naturally decaffeinated coffee plant discovered |work=[[New Scientist]] |first=Andy |last=Coghlan |date=June 23, 2004}}</ref>

==Decaffeinated tea==
{{Further|Health effects of tea}}
Tea may also be decaffeinated, usually by using processes analogous to the direct method or the CO<sub>2</sub> process, as described above. Oxidizing tea leaves to create [[black tea]] or [[oolong tea]] 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.{{citation needed|date=December 2016}} Although the CO<sub>2</sub> process is favorable because it is convenient, nonexplosive, and nontoxic,<ref>{{cite book|last1=Moyler|first1=D|editor1-last=King|editor1-first=M|editor2-last=Bott|editor2-first=Theodore|title=Extraction of Natural Products Using Near-Critical Solvents|url=https://archive.org/details/extractionnatura00king|url-access=limited|date=1993|publisher=Springer Netherlands|location=Glasgow|isbn=978-94-010-4947-4|pages=[https://archive.org/details/extractionnatura00king/page/n148 140]–183|edition=First|chapter=Extraction of flavours and fragrances with compressed CO2}}</ref> a comparison between regular and decaffeinated green teas using supercritical carbon dioxide showed that most volatile, non[[polar compound]]s (such as [[linalool]] and [[phenylacetaldehyde]]), green and floral flavor compounds (such as [[hexanal]] and (''E'')-2-[[hexenal]]), and some unknown compounds disappeared or decreased after decaffeination.<ref>{{cite journal |last1=Lee |first1=S. |last2=Park |first2=M.K. |last3=Kim |first3=K.H. |last4=Kim |first4=Y.-S. |title=Effect of Supercritical Carbon Dioxide Decaffeination on Volatile Components of Green Tea |journal=Journal of Food Science |date=September 2007 |volume=72 |issue=7 |pages=S497–S502 |doi=10.1111/j.1750-3841.2007.00446.x |pmid=17995663 }}</ref>

In addition to CO<sub>2</sub> 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&nbsp;°C or more, moderate extraction time of 3 minutes, and a 1:20 leaf to water weight per volume{{clarify|date=October 2022}} ratio removed 83% caffeine content and preserved 95% of total [[catechins]].<ref>{{cite journal |last1=Liang |first1=Huiling |last2=Liang |first2=Yuerong |last3=Dong |first3=Junjie |last4=Lu |first4=Jianliang |last5=Xu |first5=Hairong |last6=Wang |first6=Hui |title=Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment |journal=Food Chemistry |date=2007 |volume=101 |issue=4 |pages=1451–1456 |doi=10.1016/j.foodchem.2006.03.054 }}</ref> Catechins, a type of [[flavanol]], contribute to the flavor of the tea and have been shown to increase the suppression of [[mutagen]]s that may lead to cancer.<ref>{{cite journal |last1=Bu-Abbas |first1=A |last2=Nunez |first2=X |last3=Clifford |first3=M |last4=Walker |first4=R |last5=Ioannides |first5=C |title=A comparison of the antimutagenic potential of green, black and decaffeinated teas: contribution of flavanols to the antimutagenic effect |journal=Mutagenesis |date=1996 |volume=11 |issue=6 |pages=597–603 |doi=10.1093/mutage/11.6.597 |pmid=8962430 |doi-access=free }}</ref>

Both coffee and tea have [[tannins]], which are responsible for their [[astringent]] taste, but tea has around one third of the tannin content of coffee.<ref>{{cite journal |last1=Savolainen |first1=H |title=Tannin content of tea and coffee |journal=J Appl Toxicol |date=1992 |volume=12 |issue=3 |pages=191–192 |pmid=1629514 |doi=10.1002/jat.2550120307|s2cid=42678826 }}</ref> 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.<ref>{{cite journal |last1=Chung |first1=King-Thom |last2=Wong |first2=Tit Yee |last3=Wei |first3=Cheng-I |last4=Huang |first4=Yao-Wen |last5=Lin |first5=Yuan |title=Tannins and Human Health: A Review |journal=Critical Reviews in Food Science and Nutrition |date=1998 |volume=38 |issue=6 |pages=421–464 |doi=10.1080/10408699891274273 |pmid=9759559}}</ref>

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]]s, as well as more heavily fired [[Wuyi Mountain]] oolongs; commonly referred to as 'zhonghuo' (mid-fired) or 'zuhuo' (high-fired).{{Citation needed|date=February 2009}}

A generally accepted statistic is that a cup of normal black (or red) tea contains 40–50&nbsp;mg of caffeine, roughly half the content of a cup of coffee.<ref>{{cite journal |title=Tea and Caffeine |author=Upton Tea Imports |author-link=Upton Tea Imports |journal=Upton Tea Imports Newsletter |volume=16 |issue=1 |year=2003 |url=http://uptontea.com/shopcart/information/INFOnl_V13N1_Article_page1.asp |access-date=2007-01-26}}</ref>

Although a common technique of discarding a short (30 to 60 seconds) steep<ref>[https://web.archive.org/web/20120227002601/https://www.imperialtea.com/faq.php "FAQ at imperial tea court"], www.imperialtea.com, 2002</ref> 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 [[steeping|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).{{clarify|date=October 2022}}<ref>{{cite journal |title=Tea preparation and its influence on methylxanthine concentration |author=Monique B. Hicks |author2=Y.-H. Peggy Hsieh |author3=Leonard N. Bell |name-list-style=amp |journal=Food Research International |volume=29 |issue=3–4 |year=1996 |pages=325–330 |doi=10.1016/0963-9969(96)00038-5}}</ref>

==See also==
{{portal|Technology|Coffee}}
*[[Caffeine-Free Coca-Cola]]
*[[Caffeine-Free Pepsi]]
*[[Coffee substitute]]
*[[Health effects of caffeine]]
*[[Health effects of coffee]]
*[[Health effects of tea]]
*[[Low caffeine coffee]]

==References==
{{Reflist}}

{{teas}}
{{Coffee|nocat=1}}

[[Category:Caffeine]]
[[Category:Chemical processes]]
[[Category:Coffee production]]