What happens to tea over time? What can you do with old tea?

What happens to tea over time? What can you do with old tea?

You might have heard that tea has a shelf life and the claim that you should drink it within the year that it’s made (the younger the better). There is a contradiction to this with the existence of ‘aged’ tea — the older the better. The reality of this boils down to the type of tea it is, and how it’s stored.

White, Pu’Erh, and Oolong teas can age magnificently and in fact there are proverbs like “one year tea, three years medicine, seven years treasure” for white tea. “10 years is good, 20 is better, 30+ is best” for Pu’Erh tea. It’s surprising that I’ve never heard any proverb for oolong tea but as you will see below, there may be a reason why.

So what is aged and what is old? How do you know?
To know this answer you need to be informed of its storage conditions. White and Pu’Erh teas ‘age’ in a different way than oolong, but all 3 need humid conditions to transform. High temperature + high humidity will change a tea faster, than low temperature + high humidity, or high temperature + low humidity. In a place like Calgary which doesn’t really have humidity at all, ‘aging’ doesn’t happen without equipment and intent — things just get old here.

White and Pu’Erh tea ‘age’ because of their processing (actually the lack thereof). They have not been heated to the point in which all of the enzymes which can oxidize the leaf are killed and thus they live within the dried tea leaves in a near stasis. They are able to carry out their function extremely slowly thanks to moisture present in the air. The more moisture these enzymes have access to, the faster they are able to work. The natural speed of this process is extremely slow, and thus in the case of Pu’Erh tea for example, a large portion of the sales price is calculated by decades of proper aging. Connoisseurs of Pu’Erh like to know where it was aged because it gives them an idea (along with the vintage of the tea) on how mature it should have become over time (Pu’Erh aged in Hong Kong vs Malaysia for example)

Oolong ‘ages’ differently than white and Pu’Erh teas. The enzymes are killed in the initial production, so the reason for aging is more about quality control and cultural identity than flavor development. Taiwan is the place in the world when it comes to creating aged oolongs on any ‘large scale’. Taiwan is a very humid island; after a tea is finished the drying step of its production process it will likely sit in a warehouse somewhere until it sells. The moisture content of the finished and dried tea leaves will eventually creep up back to the point where mold and rot may start to take hold on the tea. If that happened the batch would be at risk of spoiling. The solution for this problem is to re-dry the tea with a gentle baking process whenever necessary (which generally is every couple years). The ‘baking’ process is what makes Taiwanese oolongs different from those of elsewhere. In an old tea, the baking process could be carried out many times, I have a tea from 1966 which has been re-baked 7 times. The unique flavors of Taiwanese aged oolongs stem from the natural flavor compounds of the tea reacting with moisture and transforming, being baked and going through maillard reactions, reacting with moisture again, baking again, etc.

A 50 year old white tea or Pu’Erh that was ‘aged’ by leaving it in a cabinet in Calgary will essentially be a dull, lifeless version of what left China 50 years prior. ‘Aged teas’ can become ‘old teas’ once they leave proper storage and move to improper storage, and that is unfortunate reality for many of them. Storing your teas properly is the key to having them taste great when you drink them. Having a 50 year old properly aged tea move across the world only for it to sit in a desert-like condition and become stale and flavorless is a true waste of what would be surely incredible tea.

So you have some old tea, what can you do with it?
There’s actually a lot you can do.
1) you can just drink your old tea, it’s not going to harm you, it just wont have very much flavor
2) you can make a flavored tea, it’s what all the big tea companies do. Cover the old flavorless tea with new flavors like vanilla, citrus zest, essential oils, etc. What a racket – it’s genius really. Buying 10KG of old black tea which didn’t sell from last years harvest (that total might come to $100 USD? it could even be less, depending on where it’s from), buy a few vials of vanilla extract or bergamot oil, sprinkle it on the black tea, wait, put it in 100g boxes and sell it for $20 each — Bam $1900 profit. This is the world of the vast majority of flavored teas. /rant
3) depending on the type of tea, you can do what the Japanese or Taiwanese do and roast the tea yourself. You can read an article I wrote about that here: https://www.sommerier.com/?p=2089
Roasted Japanese green tea is a pretty popular thing called houjicha, it’s super easy to make and a great way to give a second life to old green tea. Chinese green teas work too but I think the results are less predictable.
4) you can make blends which don’t necessarily alter the flavor of the tea, just add to it. It’s essentially another form of flavored tea by definition, but I wanted to keep this separate from point 2 because I consider this a little ‘more honest’ for some reason — there is a tea called like genmaicha in which toasted brown rice is added to old or low quality Japanese green tea, you could even put in some matcha powder if you want to get fancy.
5) there are teas like Moroccan mint tea which are essentially mocktails. To make one you would steep a green tea, add a LOT of fresh mint and white sugar or honey. This drink is delicious on ice, it’s delicious hot, it’s a big winner. It does use a lot of mint though, and while I think you could use any type of tea, it’s usually low grade Chinese green tea which makes the authentic stuff.

So at the end of the day, how old is old?
Well it depends on the type of tea, but for green and black tea ‘old is a year’. I’ve lost some great tea due to time. If it’s meant to be aged, consider storing it well. The teas which get roasted seem to hold their roasted flavor very well over time and although the ‘tea flavor’ might be gone, an old Taiwanese tea doesn’t have much ‘tea’ flavor left anyway.

What about if the tea was kept in a sealed bag, and never opened?
I can conclusively say that non-vacuum sealed teas (even in amazing packaging like sealed aluminum/tetra bags/canisters) get killed by time. If it has a vacuum seal it might be another matter, I don’t have enough experience drinking ‘old’ vacuum sealed teas to be helpful here. I think I should reiterate that a lot of this depends on the type of tea that it is though.

What about if the tea was stored in a freezer?
I’ve had one tea which was frozen to my knowledge. I got from thes-du-japon. It was a 2005 gyokuro that I bought in 2018 or 2019. Aged gyokuro is not a thing, at least not yet (I think this tea was proof that some more testing should be done). Some old product was found in vacuum sealed bags in a freezer and upon tasting the conclusion was that it was totally fine, perhaps better than it was originally. I don’t know the original quality but I concur that it was fantastic tea even after sitting in a freezer for 13 or 14 years.

What I can say is that tea shouldn’t go in and out of the freezer often. If you decide to put it in, it should be a 1 time thing. If you keep taking it in and out, condensation will build up inside the bag, the leaf will get wet, and you’ll ruin the quality of your tea very quickly. It’s the same with anything you might freeze, really.

Thank you for reading! If you have any comments or questions, please drop me a line! josh@sommerier.com