Caffeine

Caffeine, also known as trimethylxanthine, coffeine, theine, mateine, guaranine, methyltheobromine and 1,3,7-trimethylxanthine, is a xanthine alkaloid found naturally in such foods as coffee beans, tea, kola nuts, Yerba mate, guarana berries, and (in small amounts) cacao beans. For the plant, caffeine acts as a natural pesticide since it paralyzes and kills some of the insects that attempt to feed on the plant.

Sources

One common source of caffeine is the coffee plant, the beans from which are used to produce coffee. Caffeine content varies substantially between Arabica and Robusta species and to a lesser degree between varieties of each species.

Related Topics:
Coffee plant - Beans - Coffee - Arabica - Robusta

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One dose of caffeine is generally considered to be 100 mg. In theory, a single serving (6 fl oz / 150 ml) of drip coffee or one-half caffeine tablet would deliver this dose. In the real world, coffee varies considerably in caffeine content per serving, ranging from about 75 mg to 250 mg. Generally, dark roast coffee has less caffeine than lighter roasts since the roasting process reduces caffeine content of the bean.

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Tea is another common source of caffeine in many cultures. Tea contains somewhat less caffeine per serving than coffee, (usually about half as much, depending on the strength of the brew), though certain types of tea, such as Lapsang sou chong smoked teas, and oolong contain more caffeine.

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Caffeine is also common in soft drinks such as cola. Such drinks typically contain about 25 mg to 50 mg of caffeine per serving. Some "energy drinks" such as Red Bull contain 80 mg, while others offer considerably more caffeine per serving, from 100 mg to 400 mg.

Related Topics:
Soft drinks - Cola - Energy drink - Red Bull

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Mateine and guaranine are other names for caffeine. The names come from yerba maté and guarana respectively, caffeine-containing plants used for tea and other things. Many yerba maté enthusiasts insist that mateine is a stereoisomer of caffeine and thus a different substance altogether. However, this is impossible; caffeine is an achiral molecule with no chiral centers, and therefore has no stereoisomers. Similar claims are sometimes made of guaranine.

Related Topics:
Caffeine - Yerba maté - Guarana - Stereoisomer - Achiral

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Coffee

All fluid ounces are U.S. fluid ounces.

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• Coffee, brewed (drip) - 4 to 20 mg/floz (130 to 680 mg/litre) (40 to 170 mg/5 floz)
• Coffee, decaffeinated - 0.4 to 0.6 mg/floz (13 to 20 mg/litre)
• Coffee, instant - 4 to 12 mg/floz (130 to 400 mg/litre)
• Espresso Arabica - ~40 mg/floz (1.36 g/litre)
• Espresso Robusta - ~100 mg/floz (3.4 g/litre)

Teas and other infusions

• Black tea, brewed (USA) - 2.5 to 11 mg/floz (85 to 370 mg per litre)
• Black tea, brewed (other) - 3 to 14 mg/floz (100 to 470 mg/litre)
• Black tea, canned iced - 2 to 3 mg/floz (70 to 100 mg/litre)
• Black tea, instant - 3.5 mg/floz (120 mg/litre)
• Oolong, 3.75 mg/floz (120 mg per litre) (12 to 55 mg per tea bag, i.e. one serving)
• Green tea, 2.5 mg/floz (85 mg/litre) (8 to 30 mg per tea bag, i.e. one serving)
• White tea, 2.0 mg/floz (68 mg/litre) (6 to 25 mg per tea bag, i.e. one serving)
• Decaf, 0.5 mg/oz (17 mg/litre) (1 to 4 mg per tea bag, i.e. one serving)

Caffeine is sometimes called theine when it is found in tea, as the caffeine in tea was once thought to be a separate compound to the caffeine found in coffee. But tea does contain another xanthine, theophylline whose chemical structure is C7H8N4O2 compared to caffeine's C8H10N4O2. This is similar to the naming problem with mateine and guaranine.

Related Topics:
Xanthine - Theophylline - C - H - N - O

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• Tisanes (i.e. Herbal teas) - caffeine content depends on the herb, e.g. Chamomile and Rooibos "teas" have no caffeine while Yerba mate and Guarana do contain varying quantities. Many tea drinkers characterise herbal tea simply as that which, unlike black or green tea, contains no caffeine.

Chocolate

Chocolate is a weak stimulant due to to its content of theobromine, theophylline, and caffeine.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15549276

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However, chocolate contains too little of these compounds for a reasonable serving to create effects in humans that are on par with a coffee buzz.

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Other sources

• Energy drink - 10 mg/floz (340 mg/litre). Some countries limit the caffeine content at 135 mg/litre.
• Soft drink (caffeinated) - 3 to 8 mg/floz (100 to 270 mg/litre, some countries limit the caffeine content in cola drinks to 200 mg/l)
• Pill (caffeine) - 200 mg (100 mg in Canada and many countries within EU)
• Buckfast Tonic Wine - 375 mg/litre (0.05% of caffeine by weight) http://www.young.shaney.freewebspace.com/images/buckfast.jpg

Equivalents to 200 mg of caffeine

• One caffeine pill (Two in some countries where these are 100 mg)
• ~2 shots of espresso from robusta beans (2 floz)
• ~5 shots of espresso from arabica beans (5 floz)
• ~2 "5 floz containers" of regular coffee (10 floz)
• ~1.3 L soft drink (these can vary widely in content)
• ~5 cups (8 floz) of black tea or ~10 cups (8 floz) of green tea
• ~5 cans of soda (these can vary widely in content)

In the European Union, a warning must be placed on packaging if the caffeine content of any beverage exceeds 150 mg per litre. This includes caffeine from any source (including guarana, which is often found in energy drinks). In many countries, caffeine is classified as a flavouring.

Related Topics:
European Union - Guarana - Flavouring

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