（ 转帖）Which Tea has the Least/Most Caffeine?

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This is one of our most popular questions. The answer is complicated, to say the least.  Aside from our herbal caffeine-free selections, NO tea is caffeine-free.  Even decaffeinated teas retain a very small amount of caffeine after the decaffeination process (usually less than 2 mg per cup).  
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9 x- e: X; T2 s( rCaffeine occurs naturally in the leaves of the tea plant, camellia sinensis.  The amount of caffeine that is transferred from that leaf into your cup depends on many things: varietal, age of leaf, method of manufacture, production techniques, steeping time, and the water temperature used during steeping.  

/ i2 ?& s0 c& T4 u. O& rBecause there are so many variables, no one can tell you the exact amount of caffeine in your cup unless a caffeine counter is used immediately before you drink from it.  We have read documents claiming that white tea is the least caffeinated tea and others proclaiming it to be second only to black tea as the most caffeinated tea. Despite all of this, here are a few rules of thumb when it comes to understanding how much caffeine is in your tea:  
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" |: }; ^) s" L  K9 k•NO tea from the plant camellia sinensis is caffeine-free; even decaffeinated teas have a small amount of caffeine.
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% K' c. Z8 ^, W. @8 q( I5 `: M•When brewed at our recommended serving size, any variety of tea (black, green, oolong, white and pu-erh) will have less caffeine than coffee.  

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•Generally speaking, green tea brewed with 180-degree water has less caffeine than black, oolong, white and pu-erh tea. Because a lower water temperature is used during steeping, less caffeine will be extracted from the tea leaf.