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The oolongs were picked in spring 2018 and now it's November. I've made the mistake of opening a few different green oolongs and noticed that their flavor degrades rapidly, within 2 weeks they start to taste somewhat generic and lose most of the subtleties that made them high quality.

Is this a normal phenomenon and is there any way to slow down the process? Would humidity help waken up the tea again, similar to puer?
The packets have oxygen absorbers in them and I use potato chip clips to close the tea packages once they've been opened to essentially shut off all oxygen to the bag.

Sounds pretty normal to me, well two-three weeks in my experience. One reason I normally have only one green oolong open and finish within 2 weeks max. Dry climate might accelerate the process. Best consumed in a week.

If it is gone it is gone, not much you can do other than finish it off quickly.

Picking time seems less important to me, I am still drinking last Winters harvest, fresh as ever, stored in the fridge in odorless bags.

Bok wrote: ↑

Fri Nov 02, 2018 9:38 am

If it is gone it is gone, not much you can do other than finish it off quickly.

seems to be right about what is gone is gone. If subtle qualities and flavors are not gone, just being buried by another taste being stronger; then, there is a chance different preparation might mute the flavor that is being a bully. Right now I am working on a packet of foushoushan which somehow has more vegetal flavor than the other packets were giving. I've found 92C water rather than 96C, lessens the vegetal flavor's power somewhat. Helps get closer to my ideal of balanced flavors.

Something else I've noticed is that not only does the flavor significantly degrade after a few weeks, but that the teas also don't seem as caffeinating.

To be expected. That is why aged teas almost have no caffeine left in them, if any.

i agree, gaoshan is best enjoyed within a few weeks of opening it. imo about the most sensitive teas are japanese greens (matcha probably #1 most sensitive).
it's a shame, but because of that, i try hard to only have one pack of gaoshan or sencha open at a time.

however, the effect of degradation (or arguably aging) seems to be different in low-oxygen storage. this means stored with O₂ scavenger or nitrogen flushed.

imo unopened gaoshan still tastes great -- if a bit different (fruitier maybe?) -- when stored this way for a couple of years, but as soon as you open it, the freshness clock starts ticking again.

for sencha, i think it doesn't work as well. it tastes less interesting yet still different from and better than stale. aroma reminds me of hay.

also, there's no way that caffeine is appreciably degrading in just a few weeks or even a few years. caffeine's very stable.
maybe there's another explanation, but i'm not sure what it is.

I asked Stephane from Tea Masters about this problem and he sent me this answer which I thought was informative:

Green Oolongs are also called fresh Oolongs for a good reason: what is fresh and young rarely stays that way very long! Since these Oolongs have not been roasted, their moisture content is higher and causes changes in aromas when it's exposed to air (water + air + organic material = oxidation). Adding humidity, like for puerh, would actually make things worse! So, it's normal that these Oolongs would be less stable than roasted Oolongs. This raises several issues:

1. To preserve the fresh flavor longer, it's important to close the bag/foil tightly and minimize the air inside. Ideally one would have a vacuum sealer! Then keep it in a rather cool, dark and clean place. (Not the fridge, as there are too many smells there). Another tactic is to drink one fresh Oolong at a time. Only open the next package when you've finished the open one(s). Or drink them fast enough within the time frame you've observed. Some pewter tea caddies can also help preserving the fresh feel of Oolong.

2. Not all fresh Oolongs are processed the same. Even if they don't go as far as roasting them, the better high mountain Oolongs are well dried and come with a slightly higher oxidation level. Quality isn't just limited to the freshness level. This refining of the rough tea helps not only to make the Oolong stable for a longer period of time, but also to give it a better aging potential.

3. The change in aromas is part of life. Let's embrace it! A well aged high mountain Oolong can be very delicious, especially the better ones, those that were well dried and were sufficiently oxidized (the others are sometimes called 'nuclear green'). Such Oolongs can even be kept in porcelain jars. Their scents will change and loose freshness, but the taste and aftertaste will become smoother, but still powerful. And sometimes the change in scents even become positive as it adds complexity and richer aromas! But it's also a matter of managing your expectations, of course. Instead of hoping to freeze the aromas in time, expect them to change and realize that what you may have lost in terms of freshness, you might have gained in terms of finesse, elegance, depth. The taste shouldn't change that much, and if the aging is well done using my (best) Oolongs, it should even taste better!

Shine Magical wrote: ↑

Sat Nov 10, 2018 7:43 am

I asked Stephane from Tea Masters about this problem and he sent me this answer which I thought was informative:
.....

2. Not all fresh Oolongs are processed the same. Even if they don't go as far as roasting them, the better high mountain Oolongs are well dried and come with a slightly higher oxidation level. Quality isn't just limited to the freshness level. This refining of the rough tea helps not only to make the Oolong stable for a longer period of time, but also to give it a better aging potential.

3. The change in aromas is part of life. Let's embrace it! A well aged high mountain Oolong can be very delicious, especially the better ones, those that were well dried and were sufficiently oxidized (the others are sometimes called 'nuclear green'). Such Oolongs can even be kept in porcelain jars. Their scents will change and loose freshness, but the taste and aftertaste will become smoother, but still powerful. And sometimes the change in scents even become positive as it adds complexity and richer aromas! But it's also a matter of managing your expectations, of course. Instead of hoping to freeze the aromas in time, expect them to change and realize that what you may have lost in terms of freshness, you might have gained in terms of finesse, elegance, depth. The taste shouldn't change that much, and if the aging is well done using my (best) Oolongs, it should even taste better!

Ha, I had a feeling this was from Tea Masters. I enjoy reading his blog. He makes a lot of good observations. Totally agree that with skillful oxidation and drying of a quality high mountain, the tea will last a long time. Today I am sipping on thick leaf FuShouShan that was opened earlier in the Spring, sealed with a bag clip and put back in its canister; it is delicious, no degradation, possibly a little more tannic in back, but also a thicker mouthfeel, full of sweet buttery stone fruit notes, and still highly aromatic. On the other hand delicate steamed gyokuro and sencha leaves degenerate very quickly unless re-sealed with a vacuum system to remove oxygen or nitrogen flushed. I’m in the process of shopping around for a system right now, so I can divide my Japanese green 100ml bags into two 50ml and reseal.

Victoria wrote: ↑

Sat Nov 10, 2018 4:37 pm

Shine Magical wrote: ↑

Sat Nov 10, 2018 7:43 am

I asked Stephane from Tea Masters about this problem and he sent me this answer which I thought was informative:
.....

2. Not all fresh Oolongs are processed the same. Even if they don't go as far as roasting them, the better high mountain Oolongs are well dried and come with a slightly higher oxidation level. Quality isn't just limited to the freshness level. This refining of the rough tea helps not only to make the Oolong stable for a longer period of time, but also to give it a better aging potential.

3. The change in aromas is part of life. Let's embrace it! A well aged high mountain Oolong can be very delicious, especially the better ones, those that were well dried and were sufficiently oxidized (the others are sometimes called 'nuclear green'). Such Oolongs can even be kept in porcelain jars. Their scents will change and loose freshness, but the taste and aftertaste will become smoother, but still powerful. And sometimes the change in scents even become positive as it adds complexity and richer aromas! But it's also a matter of managing your expectations, of course. Instead of hoping to freeze the aromas in time, expect them to change and realize that what you may have lost in terms of freshness, you might have gained in terms of finesse, elegance, depth. The taste shouldn't change that much, and if the aging is well done using my (best) Oolongs, it should even taste better!

Ha, I had a feeling this was from Tea Masters. I enjoy reading his blog. He makes a lot of good observations. Totally agree that with skillful oxidation and drying of a quality high mountain, the tea will last a long time. Today I am sipping on thick leaf FuShouShan that was opened earlier in the Spring, sealed with a bag clip and put back in its canister; it is delicious, no degradation, possibly a little more tannic in back, but also a thicker mouthfeel, full of sweet buttery stone fruit notes, and still highly aromatic. On the other hand delicate steamed gyokuro and sencha leaves degenerate very quickly unless re-sealed with a vacuum system to remove oxygen or nitrogen flushed. I’m in the process of shopping around for a system right now, so I can divide my Japanese green 100ml bags into two 50ml and reseal.

https://www.amazon.com/PrimeTrendz-Impu ... VMKO8?th=1
https://www.amazon.com/ColorGo-Portable ... bag+sealer
Wouldn't these be a pretty inexpensive solution? The question I have is if I seal the bag each time after opening, would the tea be any different from the link below.

I've been using these but they haven't prevented the freshness issue with my gaoshan.
https://www.amazon.com/Stay-Fresh-Bag-S ... bag+sealer

You would need to remove oxygen by vacuum sealing or nitrogen flushing to retain freshness. Just closing the bag isn’t enough for longer than a few weeks with very green teas. I’m looking at these vacuum sealers from Food Savers, although I would prefer to use craft bags with foil lining. @pedant and @Baisao have discussed vacuum and nitrogen flushing systems, maybe they can comment also. Would be interesting to partially vacuum seal and then quickly nitrogen flush, and then seal bag.

Just sealing isn’t enough. Nitrogen flushing a zip-lock mylar bag works well for physically delicate teas (phoenix oolongs, baozhong, bi luo chun, etc.), but I think zipping is key to quickly locking the nitrogen in,

The best method by far is vacuum sealing balled oolongs and Japanese greens in the pine needle shape, like most sencha.

I roast gaoshan when it drops off (baozhong as well). Something to consider!

Bok wrote: ↑

Fri Nov 09, 2018 7:22 pm

To be expected. That is why aged teas almost have no caffeine left in them, if any.

Caffeine is stable in tea and doesn't diminish with ageing. Small bits are lost with re-roasting but this, according to most published research, (mostly on the caffeine content of coffee beans) is a marginal amount. My Taiwanese friends like to point to their roasters and the white powder shrouding much of them to to "prove" that roasting lowers the caffeine level but the scientific evidence says otherwise.

But then what about the effect on sleep? You can drink aged tea all night without having trouble to sleep, which can not be said about younger teas. I thought that was correlated to the caffeine? Or does the nature of it change? Not firm on the chemistry at work...