Resteeping and Caffeine?


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Resteeping and Caffeine?

Postby EDS » Mar 7th, '08, 10:32

I was curious, does Oolong tea still contain similar amounts of caffeine if steeped several times? Thanks
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Postby Mary R » Mar 7th, '08, 11:29

I sort of answered that question in this month's Between the Leaves at TeaMuse.

The main paper I cite (Hicks 1996) tested two different types of Taiwanese oolong. The first lost 66.3% of caffeine after the first steep, the second lost 71.7%. In the second steep, the first lost an additional 25.6% and the second 22.4%. In the third steep the first lost 8.1% and the second 5.9%. All infusions were for a full FIVE minutes using BOILING water.

Basically, the tea won't become truly decaffeinated until it is spent, and a quick 30s to 1.5m infusion won't remove an adequate amount of caffeine to appease those rare caffeine-sensitive folks.
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Postby hop_goblin » Mar 7th, '08, 13:04

Mary R wrote:I sort of answered that question in this month's Between the Leaves at TeaMuse.

The main paper I cite (Hicks 1996) tested two different types of Taiwanese oolong. The first lost 66.3% of caffeine after the first steep, the second lost 71.7%. In the second steep, the first lost an additional 25.6% and the second 22.4%. In the third steep the first lost 8.1% and the second 5.9%. All infusions were for a full FIVE minutes using BOILING water.

Basically, the tea won't become truly decaffeinated until it is spent, and a quick 30s to 1.5m infusion won't remove an adequate amount of caffeine to appease those rare caffeine-sensitive folks.


Yep, that is why they say that gongfu brewing is a natural way to decaffinate your tea as it gets a majority of the caffine out during the first rinse. But me loves caffine ----> me at bedtime! :shock:
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Postby scruffmcgruff » Mar 7th, '08, 13:37

Hop, I just responded to your decaffeination point in another thread, but I urge you to re-read Mary's article, as I do not think that is what she said at all.

Mary R wrote:Basically, the tea won't become truly decaffeinated until it is spent, and a quick 30s to 1.5m infusion won't remove an adequate amount of caffeine to appease those rare caffeine-sensitive folks.
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Postby tenuki » Mar 7th, '08, 13:56

don't feed the troll.
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Postby Salsero » Mar 7th, '08, 15:05

tenuki wrote:don't feed the troll.
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Postby silverneedles » Mar 7th, '08, 15:09

so they steep the 1st time 5 minutes at high temp,

looseleaf ? tea bags?
how much leaf? weight?
in how much water ? 4oz ? 10oz ? 1gal?
XX% caffeine removed...XX% out of what? 10mg ? 10mg/dl ? 100kg ?

5min after 5 min boiling is likely undrinkable to me
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Postby Mary R » Mar 7th, '08, 23:34

Good questions, silverneedles. I've excerpted the paper's abstract below.

abstract wrote:Hicks, M.B., Hsieh, P., & Bell, L.N. (1996). Tea preparation and its influence on methylxanthine concentration. Food Research International, 29, 325-330.

The amount of tea or coffee estimated from the number of cups consumed is frequently used as an indication of caffeine consumption in epidemiologic studies. However, this alone may be an inadequate indication of intake since drinking practices of tea varies. In this study, methylxanthine (caffeine, theobromine, and theophylline) contents in three brews of four types of tea (black, oolong, green, and herbal) in both bangs and loose leaf forms were investigated to determine the actual amount of methylxanthines present in tea as a function of different brewing methods. On a dry leaf weight basis, total caffeine after three brews was highest in black (32.8 mg/g) and green (36.6 mg/g) tea leaves and lowest in Formosa oolong tea 2 (23.8 mg/g). Total theobromine was highest in black teas (1.64 and 1.69 mg/g) and least in oolong teas (0.65 and 0.71 mg/g). Caffeine and theobromine were not detected in either herbal tea samples, and theophyline was not detected in any tea tested. The overall average caffeine released in the first through third brews were 69%, 23%, and 8% respectively. Three cups of tea brewed using three tea bags (Western culture) have approximatedly twice the amount of methyxanthines as the same volume prepared by three successive brews of loose tea leaves (Asian culture). These differences should be accounted for by the epidemiologic studies evaluating the effect of methylxanthines on health.


Hicks and crew used 8 different types of teas: 2 black teas (Lipton tea bags and loose Asian black tea leaves), 2 different loose Formosan oolongs, 2 green teas (Lipton green tea bags and Korean green tea leaves) and 2 herbal 'controls (Celestial Seasoning's "Lemon Mist" and International Bazaar's "Cinnamon Apple.")

For the bagged teas, 1 bag was placed in a beaker and 177ml of boiling water was poured over it. The tea was allowed to brew for 5 min and allowed to drain into the tea for an additional 30 sec.

For the loose teas, 2.3-2.5 grams of leaf were measured out and prepared in the same way. After a 5 minute brew, the leaves were placed on filter paper and allowed to drain into the tea for an additional 30 sec. The two oolong samples, however, were prepared in a ratio according to the package instructions: 3 grams in 150ml of boiling water. This worked out to be 3.5458 g/177ml.

The total amount of caffeine in each tea ranged from 23.8 mg per g of leaf to 36.6 mg per g of leaf. The full numbers are given in the article.

The infusion intervals and temperatures would be pretty undrinkable to me too...Hicks and crew weren't testing palatability, but rather showing for the first time that caffeine infusion does not follow a linear pattern.
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Postby Salsero » Mar 8th, '08, 00:24

Thanks for clarifying that for me, Mary. I didn't really quite "get it" before. Shouldn't this thread be linked to the "Discussion" thread at the end of your article?
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Postby hop_goblin » Mar 8th, '08, 11:46

Salsero wrote:
tenuki wrote:don't feed the troll.
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Don't feed the troll? :lol:
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Postby TierOne » Mar 8th, '08, 22:22

Mary R wrote:The infusion intervals and temperatures would be pretty undrinkable to me too...Hicks and crew weren't testing palatability, but rather showing for the first time that caffeine infusion does not follow a linear pattern.



Ahh. Good. 5 minutes at high temp was :shock: to me!
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