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Sheepdog
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141 Posts
Discussion Starter · #1 ·
I searched, then searched again and for good measure searched one more time with every string I could think of and couldn't find the answer....:confused:

Is it OK to use oxygen absorbers in a mylar bag (for long term food storage) in addition to vacuum sealing the bag? I've heard conflicting information and I'm trying to decide if it's one step better to add the absorber in addition to the vacuum.

Thanks
 

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Free Mason
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1,100 Posts
I would like to know also. Many times people have written do not use O2 absorber along with a vacuum seal. I have never herd the technical reason. I use a lot of canning jars for dry goods. Some I have used O2 absorbers and some I have vacuum sealed. Last week I put up some pasta that I did both.
 

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Free Mason
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You use the O2 absorber without a vacuum. It needs the head gasses to work properly. Since it's removing the O2 a vacuum wouldn't do anything anyway.
The vacuum seal removes all the gases in the air equally. Then the O2 absorber should remove the remaining O2 and stop working. If my jar lids have a small leak in a few years the O2 absorber should start working again. I hope.
 

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Mom Walton
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1,390 Posts
Oxygen absorbers perform their action through a chemical reaction. They contain iron powder which reacts with the oxygen in the air causing the iron powder to rust. When all the iron powder has oxidized, the oxygen absorbers are "loaded" and the absorbing action stops. Remove the oxygen from an active absorber and the chemical reaction stops. Put them back in the air and the reaction starts again until the iron is gone.
It is a waste of money to use the O2s if you have a vacuum packer... unless you have separate sealed bags in your bucket and you want to remove the O2 around them in the bucket. In this case the O2 does not go in the bags.

In the days before O2 packages, we used dry ice about the size of a nickel to do the same thing. Nitrogen displaced the oxygen, then you closed the bucket.

In all of these approaches, the seal is what counts when you are done. If you are going to double up anything, double up your seal... which is what you are doing by sealing the mylar bag and the bucket, (if the bucket has a gasket.)

Ever see a Mylar balloon lose its air? Well it does, especially if it is played with. Keeping your seal is the trick.
 

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Being Prepared
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311 Posts
I vac using a shop vac along with an 02 absorber. It works great. The vacum rids excess air,so the mylar bag is hard, then 3 days later, after the o2 absorber has removed the remaining oxygen, the mylar bag is rock hard with a high internal vacum. NOTHING will live in the bag, or for that matter, oxidize. I expect VERY long storage life for grains, rice, and beans.

Bubba
 

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Sheepdog
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141 Posts
Discussion Starter · #8 ·
I'm not worried about the little bit of extra cost for the O2 absorbers, I just don't want to create a problem. O2 absorbers are not that expensive. I just figured it's a little extra insurance, but wasn't sure if there would be some type of adverse reaction with the combination of vacuum and O2 absorber.
 

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Super Moderator and Walking Methane Refinery
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68,585 Posts
The vacuum seal removes all the gases in the air equally. Then the O2 absorber should remove the remaining O2 and stop working. If my jar lids have a small leak in a few years the O2 absorber should start working again. I hope.
The O2 absorber factory seems to disagree. They're the ones who said that the O2 absorbers require the head gas to work and aren't compatible with vacuum sealing.

If I remember right, O2 absorbers become inert after time and won't restart. That's been my big hesitation with trying to store a long term supply of them.
 

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Registered
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The O2 absorber factory seems to disagree. They're the ones who said that the O2 absorbers require the head gas to work and aren't compatible with vacuum sealing.

If I remember right, O2 absorbers become inert after time and won't restart. That's been my big hesitation with trying to store a long term supply of them.
I find that odd since that's how they sell them. Every order of O2's I've bought have been shipped vacuum sealed. If having less air ruins them then you'd think they'd sell them with some air in the bags.

Also a perfect vacuum is hard to get. Most vacuum sealers only draw down to about 28'' of vacuum (30" being a perfect vacuum, if memory serves me correctly).

From what I understand air is ~ 80% nitrogen and 20% oxygen, even in a partial vacuum. The O2 absorbers aren't much more then just raw iron. The iron absorbs the O2 and forms rust (FeO2), leaving N2, an inert gas. Drawing a partial vacuum shouldn't change that equation. It just leaves more raw iron that hasn't been changed to rust.

To me it's like adding extra O2 absorbers to a bag. Drawing a vacuum shouldn't hurt, unless I'm missing something.
 
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Super Moderator and Walking Methane Refinery
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I find that odd since that's how they sell them. Every order of O2's I've bought have been shipped vacuum sealed. If having less air ruins them then you'd think they'd sell them with some air in the bags.
They didn't say it ruins them. They said they need the head gas to work properly.

It's been about 15-16 years, but I think I remember them saying that circulation was part of it too. That makes sense when you think of it. If you remove most of the air, the bag sucks in tight enough that the rest might not make contact with the O2 absorber. This would leave food at the outer edges to oxidize, while that closer to the absorber wouldn't.

The absorbers reduce the O2 level to something like .2%. Reducing the amount of air isn't going to change that. If it offers no benefits, and the factory says not to do it, well, that's good enough for me. They know their product better than I do.
 
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