Oxygen Absorbers & Laminated Storage Bags

twno1
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Sun May 17, 2020 10:42 am

Anyone have any experience using oxygen absorbers and laminated PET/AL bags to store tea?

A lot of the tea I bought are in (100g) packages that do not have resealing capabilities and some are not thick enough for a sealing stick to work. I thought about buying some re-sealable PET/AL bags (like the ones Thes-Du-Japon uses) in 50g sizes and splitting a 100g bag of tea into two of these resealable bags with an oxygen absorber. However, oxygen absorbers put out heat. Would I need to be worried about the tea inside getting roasted from the oxygen absorber working?
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Victoria
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Sun May 17, 2020 2:19 pm

Moved your post from What Green Are You Drinking to here, as topic is interesting enough to have its own thread. I really don’t think oxygen absorbers put out significant heat to affect Japanese green teas. Repacking 100gram packs into two 50g packs makes sense, I would use a vacuum sealer like Foodsaver system with aluminum mylar packs. If you look in Storage area @debunix uses canning jars with vacuum seal, also here she discusses it, and @pedant links to laminate storage packs, Sample Bags.
faj
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Sun May 17, 2020 3:26 pm

A fellow member suggested vacuum packaging might crush the leaves. Maybe for Japanese teas it would not be too bad, but with delicate Chinese greens I see how the process might break the leaves.

Oxygen absorbers I have ordered are waiting for me at the office. I am planning on testing them soon with products from a vendor that supplies teas in bags that are not nitro flushed. Storing them in the refrigerator for any length of time, even when unopened, seems like a poor idea. I will open the bags, put an absorber or two inside, seal them with a vacuum sealer (without sucking the air out), and store them in the fridge. I can sample the tea before sealing the bag, just as a control step, to confirm it is fresh.

Of course, it will take a few months before I can come to any solid conclusion about the process.
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pedant
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Sun May 17, 2020 4:54 pm

i think it should be ok.

you're right that it's exothermic, but it hopefully shouldn't get too hot before the oxygen in the bag is used up. they're commonly used in tea packaging. there's no point in using them unless you're impulse sealing the bag though. also note that O2 scavengers are pretty much one time use. toss them when you next open the bags.
twno1
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Sun May 17, 2020 5:29 pm

Victoria wrote:
Sun May 17, 2020 2:19 pm
Moved your post from What Green Are You Drinking to here, as topic is interesting enough to have its own thread. I really don’t think oxygen absorbers put out significant heat to affect Japanese green teas. Repacking 100gram packs into two 50g packs makes sense, I would use a vacuum sealer like Foodsaver system with aluminum mylar packs. If you look in Storage area debunix uses canning jars with vacuum seal, also here she discusses it, and pedant links to laminate storage packs, Sample Bags.
The repacking of 100g -> 2x50g wouldn't be for "long term storage" and I would essentially be opening the 50g package every day for drinking (one at a time, of course). I remember reading a post from Hojotea where he mentions that the usage of oxygen absorbers are "better" than vacuum sealing as vacuum sealing "only" removes about 99% of oxygen.
pedant wrote:
Sun May 17, 2020 4:54 pm
there's no point in using them unless you're impulse sealing the bag though. also note that O2 scavengers are pretty much one time use. toss them when you next open the bags.
I actually plan on only using the zipper and having this be my "daily use" storage where I open and close the bag daily (or whenever I want to drink tea). On the part of oxygen absorbers being one time use - Interestingly enough, the ones I ordered are specified to work over a period of 3-5 hours and absorb 100ml of oxygen (essentially 500ml of air). The bag I bought is estimated to have 110ml of space. Assuming that tea leaves fill up most of that space and that I squeeze any excess air out before zipping it up, wouldn't these specific oxygen absorbers theoretically be "multi-use" as their stated capacity is higher than the space they're in and that they don't work immediately?
faj
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Sun May 17, 2020 8:53 pm

twno1 wrote:
Sun May 17, 2020 5:29 pm
The bag I bought is estimated to have 110ml of space. Assuming that tea leaves fill up most of that space and that I squeeze any excess air out before zipping it up, wouldn't these specific oxygen absorbers theoretically be "multi-use" as their stated capacity is higher than the space they're in and that they don't work immediately?
That makes sense, and assuming the bag is relatively leak tight and is open for short periods of time, I would be optimistic that this can work at least up to a certain point. I intend to try that. Basically, I will open the bag, put in the absorber, store the bag in the fridge, then when I take the tea out of the fridge for good I will just leave the absorber inside. The tea I intend to try this with has a history of very quickly losing its freshness, so that should be a useful test.

They still are "single-use" in the sense they cannot be "recharged". I would also say they work "slowly" rather than "not immediately".
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debunix
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Sun May 17, 2020 10:06 pm

The canning jar solution will not crush leaves, FYI.
faj
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Sun May 17, 2020 10:53 pm

debunix wrote:
Sun May 17, 2020 10:06 pm
The canning jar solution will not crush leaves, FYI.
I assume it will leave more oxygen than the absorbers, however.
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debunix
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Sun May 17, 2020 11:15 pm

Not necessarily if using the vacuum sealer on them.
faj
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Mon May 18, 2020 6:29 am

debunix wrote:
Sun May 17, 2020 11:15 pm
Not necessarily if using the vacuum sealer on them.
Vacuum sealing only removes part of the air (and therefore oxygen). I was curious to find out how much. Googling around, I find it a bit hard to find information about that, but I see products being listed as "800 mbar", which I take to mean either they remove 800 mbar of pressure (so about 80% of the air) or they reduce the pressure to 800 mbar (therefore removing about 20% of the air). 800mbar is a bit below 12 psi. Can a canning jar withstand that? Seems like it should, so 80% removal would be my guess, because removing only 20% seems quite low. Anyone knows for sure?

Of course, with vacuum, you need to take into account how much gas volume there is left. For instance, when vacuum sealing in a plastic bag, even if the pressure drops by "only" 20%, if that allows 99% of the air volume to be sucked out as the bag tightens around the item, you are left with less than 1% of the oxygen that was there in the first place. In other words, the container's shape is likely to affect the comparison between vacuum and absorbers quite a bit. And nothing, I guess, says you cannot both such the air out and put an absorber in, to get the best of both worlds.
LuckyMe
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Mon May 18, 2020 8:43 am

I experimented with Food Saver some years ago and do not recommend it for tea. It can work for fukamushi or balled oolong but as @faj mentioned, it leads to crushed leaf. The consumer grade vacuum sealers lack pressure adjustment which the professional ones have that can avoid this issue. Food Savers were designed to vacuum seal large items like meat but they can crush delicate foods.
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debunix
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Thu May 21, 2020 1:19 am

LuckyMe wrote:
Mon May 18, 2020 8:43 am
I experimented with Food Saver some years ago and do not recommend it for tea. It can work for fukamushi or balled oolong but as @faj mentioned, it leads to crushed leaf. The consumer grade vacuum sealers lack pressure adjustment which the professional ones have that can avoid this issue. Food Savers were designed to vacuum seal large items like meat but they can crush delicate foods.
These peppers are not crushed, and the vacuum is sufficient quality to require a lid opener to open the jar.
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IMG_0889.jpg (288.96 KiB) Viewed 221 times
LuckyMe
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Thu May 21, 2020 11:18 am

debunix wrote:
Thu May 21, 2020 1:19 am
LuckyMe wrote:
Mon May 18, 2020 8:43 am
I experimented with Food Saver some years ago and do not recommend it for tea. It can work for fukamushi or balled oolong but as @faj mentioned, it leads to crushed leaf. The consumer grade vacuum sealers lack pressure adjustment which the professional ones have that can avoid this issue. Food Savers were designed to vacuum seal large items like meat but they can crush delicate foods.
These peppers are not crushed, and the vacuum is sufficient quality to require a lid opener to open the jar.

Image
I was referring to items that are vacuum packed in bags not glass jars.
faj
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Thu May 21, 2020 11:52 am

LuckyMe wrote:
Thu May 21, 2020 11:18 am
These peppers are not crushed, and the vacuum is sufficient quality to require a lid opener to open the jar.
Mason jars have lids about 2.5 inches in diameter, so roughly 6 square inches in area. Suppose the vacuum removes 50% of the air (just an example). The pressure difference between the inside and outside is going to be about 7.5 psi, for a total force of more than 40 lbs. In other words, even a vacuum level that still leaves quite a bit of oxygen is likely to require some force to open. No doubt it helps reduce whatever is inside degrade slower. How much seems hard to tell without having a way to know the vacuum level generated (and maintained) in the container.

One thing is for sure : using both methods has a synergistic effect : if you include an oxygen absorber in a vacuum packed container, the absorber has less oxygen to absorb, and it is likely the vacuum improves the seal and the absorber has less leakage to content with than it would otherwise have.
twno1
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Sun May 24, 2020 4:05 am

The re-sealable alum/PET bags I bought online (same as the ones that Thes-Du-Japon uses) seem to "leak" air when I squeeze them.
If I put one filled with air under water, there are no bubbles in the water. However, if I squeeze the sealed bag under water, air bubbles will emerge from the sealed bag. Do you all think this would be a problem for long term (1 year) storage in terms of freshness?
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