Inert gas flushing at home

Post Reply
User avatar
pedant
Admin
Posts: 1516
Joined: Fri Sep 29, 2017 4:35 am
Location: Chicago
Contact:

Tue Dec 05, 2017 4:54 am

Key facets of tea preservation include reduction of: oxygen (O2) levels, moisture, light exposure, and temperature. Many vendors approach this through use of aluminized mylar packaging, which has good O2 and moisture barrier properties. Shelf life is further enhanced through use of modified atmosphere packaging (MAP) via O2 scavengers and desiccants. Vacuum sealing is sometimes used. Some vendors do inert gas flushing for sensitive teas (typically nitrogen flushing with Japanese greens from what I’ve seen). Also, inventory is sometimes refrigerated.

I’m kind of tired of having to burn through 100g of sencha in a month (neglecting other teas) to avoid wastage. Seeking to free myself from this burden, I decided to play around with MAP at home.

Image
My system consists of an argon (Ar) tank with an adjustable flowmeter connected to flexible tubing terminated with a hypodermic needle to pierce the tea packaging for flushing.

Image
Image
The flowmeter was fitted with a brass hose barb, and a short length of tubing (polyethylene, 0.5”/12.7mm OD, 0.375”/9.5mm ID) was jammed onto it to act as a semi-flexible coupler. A bit of electrical tape made it a snug fit, and it was secured with a hose clamp. A 3cc syringe with Luer lock (with the finger flange sliced off) was then snugly jammed into the tubing. A compressed wad of "poly-fil" polyester fiber fill was stuffed into the syringe to act as a filter just in case. It will be interesting to examine the appearance of the filter after some usage – hopefully it’ll be spotless.

Image
A medical “monitoring line” (PVC, 72”/182.9cm, male-to-female Luer lock terminated) was then attached to the syringe and fitted with an 18 gauge needle.

Image
Tea packaging is modified by applying blobs of silicone sealant which, when cured, act as self-healing injector ports. One port is the Ar inlet, and the other is the outlet.

Image
These things (adhesive-backed ports) might be a nice alternative, but I haven’t shopped for them. Silicone sealant works fine.

Image
With the packaging impulse sealed, a bare needle is inserted into one port as the outlet, and the Argon line needle is inserted into the other port. I’m flushing the packaging for a couple of minutes with occasional shaking. I also deflate the bag by squeezing it and flush it once more at the end. I should get some of those oxygen indicator tablets or something to see how long it’s really necessary to flush for.
http://www.sorbentsystems.com/tell-tab.html
If someone has other indicator suggestions, please let me know.

When shincha is upon us, I’ll take a packet, drink some, and then experiment with the unused portion by dividing it into 4 sealed packs and subjecting them to: room temp without flushing (control), refrigeration without flushing, room temp with flushing, and refrigeration with flushing. I’ll open them some months later and compare them blind.

Of course, this can be used to extend the shelf life of any sensitive tea.

A note about the argon: it is industrial grade (reported >= 95%) that I have for TIG welding, but I’m working under the assumption that the contaminants are basically other atmospheric components (N2, O2, H2O, etc.). The likely contaminants I’m interested in are O2 and H2O. Even if the tank is 5% H2O, after poking around in a thermo textbook, it looks like that would be under 4% RH @ STP, which seems pretty dry. The other worst-case scenario is that it’s 5% O2. Atmosphere contains about 21% O2, so even 5% would be a significant reduction. Those are worst-case scenarios though. High purity gasses (>99.9%) are available, and I may get a new N2 or Ar tank if I can find a reasonable supplier. My current supplier informed me that they only do rentals for high-purity gasses, so I’ll have to shop around. I’d appreciate any hints here (especially for a smaller size tank). However, if my test results are good, then I might not bother with a new one.

Why not just use O2 scavengers instead? Arguably a more sane solution. A main reason is that I haven’t found small ones individually sealed. I think it would be great if someone sold them like that for a reasonable price.
User avatar
Victoria
Admin
Posts: 3043
Joined: Sat Sep 30, 2017 3:33 pm
Location: Santa Monica, CA
Contact:

Tue Dec 05, 2017 7:26 am

Amazing thread, hats off to you, it’s impressive.
Atlas
Posts: 138
Joined: Mon Nov 27, 2017 7:09 pm
Location: SGV, Los Angeles CA
Contact:

Wed Dec 06, 2017 12:10 am

That's some serious dedication to freshness!

I'd be interested to see the results of cracking two packs of the same tea (say a sencha or something similarly sensitive), vac-sealing one and MAPing the other, and tasting a few months down the road to compare.
User avatar
debunix
Posts: 1812
Joined: Sat Oct 21, 2017 1:27 am
Location: Los Angeles, CA

Wed Dec 06, 2017 11:23 am

Food-grade CO2 is easy to find: I've got a small setup for sparkling water (for sparkling sencha!), and a larger tank I used for injecting CO2 into freshwater aquariums for better plant growth. I wonder if it would have any beneficial effect on tea?
User avatar
beachape
Posts: 31
Joined: Thu Dec 14, 2017 1:06 pm
Location: Pennsylvania

Sun Dec 17, 2017 10:41 pm

I like the scientific method you have proposed with a blind test. I briefly used a nitrogen flush with those disposable bottles used for wine and couldn't tell much difference. Doubt I really got any nitrogen in the bag though.
User avatar
_Soggy_
Posts: 63
Joined: Mon Dec 11, 2017 5:11 pm
Location: Chicago

Wed Dec 20, 2017 12:51 pm

Pedant, I think this will be fun experiment to do blind. I'm curious how it will affect other teas as well. Would it preserve a roast and moisture creep of a yancha? How will it affect aging puerh? Yesterday, I tried looking up which bacteria and fungal is aerobic and anaerobic but I didn't get much information (over my head). It seemed like you can't get low enough oxygen anyways to be anaerobic.
User avatar
Baisao
Posts: 1397
Joined: Mon Dec 11, 2017 5:17 pm
Location: ATX

Tue Jan 30, 2018 12:59 am

I’ve been using a product used for wine called Private Preserve. It is nitrogen and argon, if I remember correctly (been a long time simce I’ve read the bottle).

I use it to replace oxygen in delicate teas that cannot be vacuum sealed but would benefit from storage in a very low oxygen environment. I use mylar opaque mylar bags or brown glass jars. It’s convenient and takes less than 30 seconds to flush a bag/jar before sealing.

I don’t do this for all teas. In fact, I tend to let my more oxidized tea rest or age. But some teas are better off fresh, like Taiwanese Bi Luo Chun, and cannot be vacuum sealed without damaging the leaves. This is a perfect candidate for inert gas flushing.
User avatar
Nis
Posts: 72
Joined: Tue Dec 12, 2017 7:13 am
Location: France

Tue Jan 30, 2018 1:26 pm

pedant wrote:
Tue Dec 05, 2017 4:54 am
Why not just use O2 scavengers instead? Arguably a more sane solution. A main reason is that I haven’t found small ones individually sealed. I think it would be great if someone sold them like that for a reasonable price.
I wonder if repacking them yourself in zip-lock mylar bags would be good enough.
User avatar
Baisao
Posts: 1397
Joined: Mon Dec 11, 2017 5:17 pm
Location: ATX

Tue Jan 30, 2018 1:46 pm

Nis wrote:
Tue Jan 30, 2018 1:26 pm
pedant wrote:
Tue Dec 05, 2017 4:54 am
Why not just use O2 scavengers instead? Arguably a more sane solution. A main reason is that I haven’t found small ones individually sealed. I think it would be great if someone sold them like that for a reasonable price.
I wonder if repacking them yourself in zip-lock mylar bags would be good enough.
I've vacuum sealed them with success to keep them from deactivating. The issue I find with them is that they seem to only be useful in very small spaces. For example, they work well in a vacuum sealed bag of tea but deactivate rapidly in a bag that has the air casually pressed out of it.
User avatar
Nis
Posts: 72
Joined: Tue Dec 12, 2017 7:13 am
Location: France

Tue Jan 30, 2018 1:59 pm

Baisao wrote:
Tue Jan 30, 2018 1:46 pm
Nis wrote:
Tue Jan 30, 2018 1:26 pm
I wonder if repacking them yourself in zip-lock mylar bags would be good enough.
I've vacuum sealed them with success to keep them from deactivating. The issue I find with them is that they seem to only be useful in very small spaces. For example, they work well in a vacuum sealed bag of tea but deactivate rapidly in a bag that has the air casually pressed out of it.
You do need to use the right number of packets for the volume.
This site has information on that: https://www.usaemergencysupply.com/info ... rber-types
Post Reply