Longevity in teas?


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Longevity in teas?

Postby LowInFat » Nov 4th, '12, 01:29

As we all know, most teas go bad after a while. Not in that they spoil and can't be consumed, but in that they lose freshness and aren't quite as enjoyable as when new. Of course, some teas like sheng puer and certain aged oolongs actually get better with age, but for the most part this holds true. Still, it is my understanding that there is some variation in just how quickly certain teas go bad. My current understanding is very limited and possibly incorrect: Most herbal teas keep rather poorly. Green and white teas also lose freshness fast. Black teas and oolongs keep well, but not tieguanyin, and some oolongs and puers keep indefinitely, often getting even better with age if stored correctly. This is obviously very generalized, but that's my understanding.

Would anyone care to explain longevity in different teas, why certain teas keep better than others, and what I can look for in determining how well a tea will keep?
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Re: Longevity in teas?

Postby MacGuffin » Nov 4th, '12, 10:39

I can't say for sure how long teas keep fresh for optimal conventional brewing but I'm cleaning out my "green" drawer and much of it is literally years old--some of it's open, some not. The stuff that's sealed is still kind of okay for conventional brewing and the open stuff is hopeless, HOWEVER, almost all of it is delicious (not just drinkable, mind you) if you have no objection to making refrigerator tea from it--the very few that weren't delicious were "mnyeh" rather than actually bad. In fact, at this very moment I'm enjoying some less-than-stellar green tea from Japan that was given to me in 2005 (dated package) by a friend who didn't know I knew better. I'd never opened it but decided to consign it to the fridge and it's delicious--sweet and lingeringly umami-rich. Once it's finished, it's on to the next.

On the other hand, I tried some old/open CTC Assam tea that didn't give up much when made the same way but to be honest, I don't remember how its quality was when it was new and brewed hot--my tea buddy Amy is making cold tea from a current batch of the same tea and is in raptures. I guess you never know. I'm hoarding some unopened oolongs, including bai ji guan and almond blossom dan cong that will NEVER receive such "disrespectful" treatment but the greens are fair game. :) I guess my point is that if you have no objection to cold tea, you needn't discard anything on the basis of age.
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Re: Longevity in teas?

Postby debunix » Nov 4th, '12, 12:57

My best understanding of this is that some of the flavors we enjoy in teas are very transient, not easily fixed by oxidation or baking, and those will fade rapidly or slowly depending on storage conditions, and others are more durable and may even improve with aging.

Delicate floral and vegetal notes go first, so the delicate first flush greens and minimally processed green oolongs go off quickly. Those I try to buy in small quantity, to be used within a year, and ideally, especially for the oolongs, in vacuum or nitrogen flushed packages of no more than 50 g each.

Earthy & spicy notes seem to last longest--e.g., deliberately aged puerhs, aged oolongs--so I buy occasional beengs of puerh and more deeply roasted/traditional oolongs (whether Wuyi, Anxi, Taiwanese, or similar teas from Korea (Balhyocha/yellows) that I really like up to 100g at a time.

Some sweet, nutty, and fruity notes are very durable, showing up in aged puerhs and oolongs, but I suspect these elements are more variable in their longevity. So a grassy nutty green tea might be ok in larger quantity (100g) than a fancy early bud tea from April, and I might be willing to buy 100g increments of a not-so-delicate but still lightly roasted oolong for everyday drinking.

Does that help?

I bet someone out there has far more detailed data on degradation of different tea flavor compounds.
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