Decaffeination is the removal of caffeine from coffee beans, cocoa,
tea leaves, and other caffeine-containing materials. While soft drinks
which do not use caffeine as an ingredient are sometimes described as
"decaffeinated", they are better termed "non-caffeinated" because
decaffeinated implies that there was caffeine present at one point in
time. Decaffeinated drinks contain typically 1–2% of the original
caffeine content, and sometimes as much as 20%. Decaffeinated
products are commonly termed decaf.
Decaffeination processes for coffee
2.1 Common characteristics of decaffeination
2.2 Swiss Water process
2.3 Organic solvent processes
2.3.1 Solvents used in decaffeination
2.3.2 Direct method
2.3.3 Indirect method
2.4 CO2 process
2.5 Triglyceride process
3 Decaffeinated coffee
Caffeine content of coffee
Caffeine content of decaffeinated coffee
5 Decaffeinated tea
6 See also
Friedlieb Ferdinand Runge
Friedlieb Ferdinand Runge performed the first isolation of pure
caffeine from coffee beans in 1820. He did this after the poet Goethe
requested he perform an analysis on coffee beans after seeing his work
on belladonna extract. 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
The first commercially successful decaffeination process was invented
by German merchant
Ludwig Roselius and co-workers in 1903 and patented
in 1906. In 1903, Ludwig accidentally stumbled upon this method
when his freight of coffee beans was soaked in sea water and lost much
of its caffeine without losing much taste. This original
decaffeination process involved steaming coffee beans with various
acids or bases, then using benzene as a solvent to remove the
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
France and later
Sanka brand coffee in the US
Café HAG and
Sanka are now worldwide
brands of Kraft Foods. Because of health concerns regarding benzene
(which is recognised today as a carcinogen), benzene is no longer
used as a solvent commercially.
Since its inception, methods of decaffeination similar to those first
developed by Roselius have continued to dominate. While Roselius used
benzene, many different solvents have since been tried after learning
of the potential harmful effects of benzene. The most prevalent
solvents used to date are dichloromethane and ethyl acetate.
Another variation of Roselius' method is the indirect organic solvent
method. This is very similar to the process described above, only
instead of treating the beans directly, water resulting from the
soaking of beans is treated with solvents and the process goes on
until equilibrium is reached without caffeine in the beans. 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.
Another process, known as the Swiss Water Method, uses solely water
and osmosis to decaffeinate beans. The use of water as the solvent to
decaffeinate coffee was originally pioneered in Switzerland in 1933
and developed as a commercially viable method of decaffeination by
Coffex S.A. in 1980. In 1988, the Swiss Water Method was introduced
by The Swiss Water Decaffeinated
Coffee Company of Burnaby, British
Columbia, Canada. Noted food engineer
Torunn Atteraas Garin also
developed a process to remove caffeine from coffee.
Most recently, food scientists have turned to supercritical carbon
dioxide as a means of decaffeination. Developed by Kurt Zosel, a
scientist of the Max Planck Institute, it uses CO2, heated and
pressurized above its critical point, to extract caffeine and could
be useful going forward because it circumvents the use of other
solvents and their possible effects entirely.
Decaffeination processes for coffee
In the case of coffee, various methods can be used. The process is
performed on unroasted (green) beans and starts with steaming of the
beans. They are then rinsed with a solvent that 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).
Common characteristics of decaffeination
In all decaffeination processes, coffee is always decaffeinated in its
green, unroasted state. The greatest challenge to the decaffeination
process is to try to separate only the caffeine from the coffee beans
while leaving the other chemicals such as sucrose, cellulose,
proteins, citric acid, tartaric acid, and formic acid at their
original concentrations. This is not an easy task considering coffee
contains somewhere around 1,000 chemicals that contribute to the taste
and aroma. Since caffeine is a polar, water-soluble substance,
water is used in all forms of decaffeination. However, water alone is
not the best solution for decaffeination because it is not a selective
solvent and therefore removes other soluble substances, including
sugars and proteins, as well as caffeine. Therefore, most
decaffeination processes use a decaffeinating agent such as methylene
chloride, activated charcoal, CO2, or ethyl acetate. These agents
help speed up the process and minimize the "washed-out" effects that
water alone might have on the taste of decaffeinated coffee.
Swiss Water process
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The Swiss Water Process involves soaking the green coffee in water,
allowing the caffeine (and other soluble components) to be dissolved,
and later returning flavor components to the green coffee after
removing the caffeine from the solution.
The Swiss Water 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 the
caffeine. The process relies on the stability of the soluble
components of the GCE and the gradient pressure difference between the
GCE (which is caffeine lean) and the green coffee (which is caffeine
rich). This gradient pressure 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.
Once the GCE is rich with caffeine it is then percolated through
carbon absorbers which attract the caffeine molecule from the GCE
while leaving other green coffee elements intact in the GCE. When the
GCE is once again lean of caffeine it is then used to remove
additional caffeine from the green coffee. This is a continuous batch
process that take 8–10 hours to meet the final residual
Organic solvent processes
Solvents used in decaffeination
Given numerous health scares connected to early efforts in
decaffeination using solvents such as benzene, trichloroethylene,
and chloroform, the solvents of choice have become dichloromethane and
Dichloromethane is able to extract the caffeine
selectively and has a low boiling point. Although it is mildly toxic
and carcinogenic, its use as a decaffeination agent is allowed by
the US Food and Drug Administration if the residual solvent is less
than 10 parts per million (ppm). Actual coffee industry practice
results in residues closer to one part per million. Starting in the
1980s, ethyl acetate was introduced as a replacement to
dichloromethane. Although ethyl acetate is mildly toxic,
coffee that is decaffeinated with this solvent is sometimes marketed
as "naturally decaffeinated" because this solvent may be obtained from
a biological process such as the fermentation of sugar cane.
In the direct method, the coffee beans are first steamed for 30
minutes to open their pores and then repeatedly rinsed with either
dichloromethane or ethyl acetate for about 10 hours to remove the
caffeine. The caffeine-laden solvent is then drained away and the
beans steamed to remove residual solvent.
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 dichloromethane 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, 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
This process has been referred to as CO2 Method, Liquid Carbon Dioxide
Method, and Supercritical Carbon Dioxide method but it is technically
known as supercritical fluid extraction.
The supercritical CO2 acts selectively on the caffeine, releasing the
alkaloid and nothing else. Water-soaked coffee beans are placed in an
extraction vessel. The extractor is then sealed and supercritical CO2
is forced into the coffee at pressures of 1,000 pounds per square inch
(about 69 bar) to extract the caffeine. The CO2 acts as the solvent
to dissolve and draw the caffeine from the coffee beans, leaving the
larger-molecule flavor components behind. The caffeine-laden CO2 is
then transferred to another container called the absorption chamber
where the pressure is released and the CO2 returns to its gaseous
state and evaporates, leaving the caffeine behind. The caffeine is
removed from the CO2 using charcoal filters, and the caffeine free CO2
is pumped back into a pressurized container for reuse on another batch
of beans. This process has the advantage that it avoids the use of
potentially harmful substances. Because of its cost, this process is
primarily used to decaffeinate large quantities of commercial-grade,
less-exotic coffee found in grocery stores.
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 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.
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 (no less than 97% caffeine content
reduction according to
United States standards). To do so, many
coffee companies choose to employ High-performance liquid
chromatography to quantitatively 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 quantify remaining caffeine
includes Ultraviolet–visible spectroscopy, which can be greatly
advantageous for decaffeination processes that include supercritical
CO2, as CO2 does not absorb in the UV-Vis range.
A controlled study 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 16-ounce (473-ml) 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. An 8-ounce
(237-ml) cup of regular coffee contains 95–200 mg of
caffeine, and a 12-ounce (355-milliliter) serving of Coca-Cola
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.
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 decaffeinated coffee, and trademarked in
The prospect for Decaffito-type coffees was shown by the discovery of
the naturally caffeine-free
Coffea charrieriana, reported in 2004. It
has a deficient caffeine synthase gene, leading it to accumulate
theobromine 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 the gene for caffeine synthase in normal coffee plants.
Further information: Health effects of tea
Tea may also be decaffeinated, usually by using processes analogous to
the direct method or the CO2 process, as described above. The process
of oxidizing tea leaves to create black tea ("red" in Chinese tea
culture) 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
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.
Although the CO2 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, nonpolar compounds (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.
In addition to CO2 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, where
higher temperatures at or over 100 °C, moderate extraction time
of 3 minutes, and a 1:20 water to leaf weight per volume ratio removed
83% caffeine content and preserved 95% of total catechins.
Catechins, a type of flavanol, contribute to the flavor of the tea and
also, interestingly, have been shown to increase suppression of
mutagens that may lead to cancer.
Both coffee and tea have tannins, which is responsible for the
astringent taste, but tea has nearly three times smaller tannin
content than 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 antimicrobrial
properties. Specifically, tannins accelerate blood clotting, reduce
blood pressure, decrease the serum lipid level, produce liver
necrosis, 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. Several instances in China where
this is evident is in many cooked pu-erh teas, as well as more heavily
Wuyi Mountain oolongs; commonly referred to as 'zhonghuo'
(mid-fired) or 'zuhuo' (high-fired).
A generally accepted statistic is that a cup of normal black (often
called red in China; as distinct from green) tea contains
40–50 mg of caffeine, roughly half the content of a cup of
Although a common technique of discarding a short (30- to 60-second)
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).
Health effects of caffeine
Health effects of coffee
Health effects of tea
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Tea (Camellia sinensis)
Lapsang souchong (Jin Jun Mei)
Ban Tian Yao
Bu Zhi Chun
Da Hong Pao
Shui Jin Gui
Anji bai cha
Lu'an Melon Seed
Earl Grey (Lady Grey)
Breakfast tea (English, Irish)
Moroccan mint tea
Prince of Wales
Afternoon/High tea/Evening meal
Chashitsu (tea room)
Mizuya (prep room)
Teahouse circuit or trek (Himalayas)
Tea processing (
Tea leaf grading)
Tea plant diseases and
Tea plant predation
Ground or pressed (
Tea and health
Flavan-3-ol (Catechin), Epigallocatechin gallate
Consumption by country
Doodh pati chai
Hong Kong-style milk tea
7 layered Tea
Tea set (Brewing: Strainer or Infuser, Utensils:
Teacup or Teapot)
Bak kut teh
List of Chinese teas
Lipton Institute of Tea
Teas of related species
Tea seed oil
Tea Task Force
List of countries by coffee production
Species and varieties
Coffee Pot Control Protocol
List of coffee dishes
Cà phê sữa đá
Café au lait
Café de olla
Café con leche
Café com Cheirinho
Greek frappé coffee
Indian filter coffee
Ipoh white coffee
Viennese coffee house
Roasted grain drink
Coffee and doughnuts
Coffee cup sleeve
Tasse à café
Coffee leaf rust
King Gustav's twin experiment
Coffee vending machine
Single-serve coffee container
Third wave of coffee