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EDITOR'S NOTE: When it comes to the topic of caffeine in tea, there is no end to the generating of myth and indeed of science fiction. Perhaps the most persistent canard is the one that alleges that tea can be 'mostly' decaffeinated (80% is, I think, the number most often quoted) by a quick preliminary infusion in hot water (30 seconds is the duration typically recommended). While one cannot hope to dispel so-called 'common wisdom' overnight, even by the demonstration of clear scientific fact, it is surely a step in the right direction to put the data into public circulation. That is why I have asked Nigel Melican, founder and Managing Director of Teacraft Ltd, to offer us a post on this and other aspects of caffeine in tea. Nigel is, quite simply, one of the world's leading authorities on tea; readers of CHA DAO will recall with pleasure the massive work of bibliography that he contributed to this blog in an earlier post; today's entry is, I think, destined to become a standard compendium of information on the topic.
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19 Feb 14
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Perhaps the most persistent canard is the one that alleges that tea can be 'mostly' decaffeinated (80% is, I think, the number most often quoted) by a quick preliminary infusion in hot water (30 seconds is the duration typically recommended).
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In the case of tea, this is provided commercially by a process that uses organic solvents to remove most of the offending caffeine
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commercial decaffeination is an expensive process that takes hours of production time and doubles the raw material price of a pound of tea.
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30 seconds: 9% caffeine removal
1 minute: 18% caffeine removal
2 minutes: 34% caffeine removal
3 minutes: 48% caffeine removal
4 minutes: 60% caffeine removal
5 minutes: 69% caffeine removal
10 minutes: 92% caffeine removal
15 minutes: 100% caffeine removal -
Another much-repeated claim is that black tea is high in caffeine, green tea is lower, and white tea (through the naturalness of its manufacture it is implied) has next to none. While suiting the sales pitch of some tea vendors this information is so wrong as to verge on the fraudulent.
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Actual caffeine level in tea is highest:
• when the tea is derived from buds and young first leaf tips (thus white tea has a high caffeine level) -
All of this goes to show that quoting any particular caffeine percentage for a given tea type, as many people do, should be fringed with caveats, and the exact data provided as to how it was processed and when it was grown. At best (using HPLC analysis), a precise and accurate caffeine-content measure is but a snapshot in time. And in the main, none of this information is available to the tea producer, let alone to the seller.
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The natural complexing of caffeine in tea (it binds with tea polyphenols during steeping) gives a slower and more gentle uptake in the stomach and hence to the brain; and I suspect that the relaxing effect of tea's own mind-calming amino acid (theanine) also contributes to the body's reacting more gently to tea caffeine than to coffee caffeine.
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27 Nov 09
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17 Oct 09
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II. CAFFEINE LEVELS IN VARIOUS TEAS
Another much-repeated claim is that black tea is high in caffeine, green tea is lower, and white tea (through the naturalness of its manufacture it is implied) has next to none. While suiting the sales pitch of some tea vendors this information is so wrong as to verge on the fraudulent.
Three scientifically verifiable facts are:
1. Caffeine level varies naturally in types of tea and levels in one type may overlap with another type
2. Black and green tea manufactured from leaf from the same bushes on the same day will have virtually the same caffeine levels (within +/- 0.3%)
3. For a given bush, the finer the plucking standard, the higher the caffeine level
Actual caffeine level in tea is highest:
• when the tea is derived from buds and young first leaf tips (thus white tea has a high caffeine level)
• when the bush is assamica type rather than sinensis (can be 33% higher caffeine, thus African black tea tends to be higher than China black tea)
• when the bush is clonal VP rather than seedling (can be 100% higher caffeine, thus new plantings in Africa are higher than old seedling plantings in Asia),
• when the plant is given a lot of nitrogen fertilizer (as in Japan), and
• during fast growing seasons.
Thus tea derived from older leaf, China type seedling bush, under-fertilized husbandry and in autumn season will naturally be lowest in caffeine. Georgian and Turkish tea falls into this category: expect only 1 to 1.5% caffeine in them, compared with the usual 3% in retail teas. Tea from well-fertilized fast-growing young tips of African clonal tea can often have 5-6% caffeine. -
The natural complexing of caffeine in tea (it binds with tea polyphenols during steeping) gives a slower and more gentle uptake in the stomach and hence to the brain; and I suspect that the relaxing effect of tea's own mind-calming amino acid (theanine) also contributes to the body's reacting more gently to tea caffeine than to coffee caffeine.
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First and most importantly, let us remember that tea was designed by Mother Nature to have caffeine in it – indeed it is caffeine that is demonstrably the primary reason that tea (and coffee, cacao, and mate) became popular beverages.
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16 Sep 08
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EDITOR'S NOTE: When it comes to the topic of caffeine in tea, there is no end to the generating of myth and indeed of science fiction. Perhaps the most persistent canard is the one that alleges that tea can be 'mostly' decaffeinated (80% is, I think, the number most often quoted) by a quick preliminary infusion in hot water (30 seconds is the duration typically recommended). While one cannot hope to dispel so-called 'common wisdom' overnight, even by the demonstration of clear scientific fact, it is surely a step in the right direction to put the data into public circulation. That is why I have asked Nigel Melican, founder and Managing Director of Teacraft Ltd, to offer us a post on this and other aspects of caffeine in tea. Nigel is, quite simply, one of the world's leading authorities on tea; readers of CHA DAO will recall with pleasure the massive work of bibliography that he contributed to this blog in an earlier post; today's entry is, I think, destined to become a standard compendium of information on the topic. I. DECAFFEINATING TEA Tea contains two physiologically active compounds: caffeine and theanine. Moderate caffeine consumption is perceived by some in western countries to border on the dangerous, and many consumers, rather than abstaining entirely from drinking tea, maté, or coffee, demand a decaffeinated version. In the case of tea, this is provided commercially by a process that uses organic solvents to remove most of the offending caffeine (along with other compounds); the result, unfortunately, is at best an indifferent product. (Ironically, the very caffeine so removed is a valuable by-product eagerly sought by soft-drink manufacturers to enhance their sugary beverages.) As well as reducing product quality, commercial decaffeination is an expensive process that takes hours of production time and doubles the raw material price of a pound of tea. How likely is it therefore that the accountants at Lipton and similar packers would have overl
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28 Mar 08
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