Disclaimer, please read!
Yes, I know what a tisane is. No, this isn't just fresh/dried mint leaves put in hot water. No, I didn't invent anything new.
This is a followup to a previous post where I light-heartedly introduced this topic, not paying enough attention to the level of details.
here I want to redeem myself, talking about a fun experiment where I apply some orthodox Camellia sinensis processing techniques to other botanical species (such as Mentha spicata, spearmint, in this post), to develop a deeper flavor profile on a molecular level!
You can find the previous post for context here.
Also, quick TL;DR: if you're interested in the process to try making this "GABA" mint tea more than in my endless yapping, scroll down!

Premise

Standard tisanes have something in common: they are made from dried herbs and plants. Passive dehydration leads to a baseline volatile profile (mostly monoterpenes). Furthermore, on the contrary of what one could think, leaves are not super permeable and that's why tisanes usually require 100°C and well above 5 min of infusion (I have some that suggest over 10). Orthodox tea processing is exactly what historically served the purpose of improving these factors:

• Cellular stress: needed to alter metabolic pathways. Plucked leaves are still live organisms with working metabolism; bruising, rolling, anaerobiosis... are processes that alter it and develop a different flavor profile, mainly through oxidation.
• Thermal deactivation: to stop enzymes responsible of said oxidation (PPO and such), fixing the final product at a specific oxidation level (think of the 6 orthodox tea categories).
• Precursors: light carbohydrates are broken down, aminoacids are accumulated, and volatile compounds generated through roasting are given time to escape the cellular matrix, developing a round and balanced flavor profile.

The (Old) Experiment

As I said, I haven't invented anything. Cultural traditions involving "tea processes" applied to different plants (mint, fireweed, berry bushes) are as old as tea itself, but somehow they disappeared through time, forgotten or substituted. Why? I don't know, I'm interested in this aspect but that's outside the scope of this post, but there are a lot of YouTube channels, articles and blogs talking about this phenomenon.

And this is where my previous controversial post starts. One of said channels, called Honoring Nature, made its way to my homepage and presented me a world of possibilities I haven't previously considered (but many did, and I'm glad for that!): applying orthodox tea crafting to other plants that biologically and chemically allow it.

Now: I have a lot of wild spearmint in my garden. I don't know what to do with it. I recently started trying these "fake teas" picking up plants from my garden, and I thought: could I do the same with all this mint? When bruised, it oxidises and gets bitter very fast... are there any processes in the tea industry that can prevent this from happening?
I ended up reading about GABA oolong tea, which undergoes anaerobic stress to induce production of its namesake aminoacid, and decided to try this process.

Procedure

I've talked enough, now it's time to get our hands dirty.

I picked the youngest leaves possible (since we are in late summer, and here spearmint is almost flowering sadly), gently brushed them with a soft cloth being as light as possible and then started the real process. This is what I did, but it is still heavily improvable:

1. Withering: Indoor, for 4-6 hours at max, until leaves lose their initial stiffness and become somewhat flaccid.
2. Anaerobic Stress: Real GABA tea would require a nitrogen-saturated gas chamber, which I obviously don't own. While the process is not strictly the same, the idea here is to completely stop oxidation (PPO requires oxygen) by putting the leaves under vacuum. This was performed by using food vacuum containers. I left the leaves in a dry cool area in complete darkness for 12 hours.
3. Kill-green: Pan-fired on a hot wok, measured temperature with IR thermometer at around 130-150°C. This is needed to fix the color and stop the oxidation (enzyme denaturation), that would otherwise start again once out in the air: 130°C is indicative, but should allow for a rapid and homogeneous heat transfer, time required depends on your batch (small batches are done in under two minutes of consistent heat). Move the leaves often, with the help of a soft clamp (heat-safe) or your hands with heatproof gloves.
4. Drying: Residual water has to go, ideally as fast as possible. I left the leaves in the oven at 50°C with the lid open (with the help of a wooden spoon) for around 20-30 min, or as soon as the biggest leaf can be snapped in half with no resistance or flexibility.
5. Resting: This is the most important part when making tea (both real and "fake") at home. The leaves need to rest, allowing the various aromatic compounds to set and develop a balanced and characteristic flavor profile. I left my mint in the same, cleaned glass container from before (but NOT under vacuum!) for at least 1 week.

Then it's time to brew!
I got under 2g of dry leaves, so it was barely enough for a decent gongfu session, but it surprised me how the leaves were able to infuse for over 4 total minutes at 90°C, developing a smooth, clear liquor with fruity sweet notes and a pleasant minty aftertaste, which was nowhere near strong enough to overcome the other flavors.

Things to improve

While the final result was really pleasant and unexpected, dare I say it was insane, it was not without mistakes and downsides.
The leaves gradually became darker infusion after infusion, proving the kill-green step was not 100% complete; anaerobic stress worked (fruity notes that were absent in the original mass), but I suspect it could go a bit longer; and most obviously, I could've picked the spearmint when it was fresh and aromatic, rather than approaching flowering and losing part of its fragrance... there's still plenty of room for improvement.
Also, I study Chemistry, but biochemistry is not my main field, so please if you have more details or tips please tell me!

Again, I want to remind that this is not my invention, I'm sure many have actually tried making this type of tea and documented a better and more accurate process than mine...
My aim with this post is just to share with you my personal experience, and encourage anyone that wants to try and make their own tea by doing something slightly more challenging than just drying wild herbs. Tea biology is unbelievable and we all love it, but nature is wonderful and many other plants have such an underexplored or underappreciated potential in this sector.

Please be careful about what you pick/identify and potential safety hazards!

I just saw a biology meme about killer cells and decided to childishly make one about glycochemistry (🤍)
These AI Google replies always throw me off.
It’s the instant threat assessment that gets me…