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How to Use and Store Oxygen Absorbers for Freeze Drying or Long Term Food Storage

What are Oxygen Absorbers?

Oxygen absorbers are packets containing iron powder sealed in a small packet made of material approved for contact with food.

How Do Oxygen Absorbers Work?

The packet is added to a Mylar bag or jar when preparing food for long term storage. The oxygen absorber removes oxygen through a chemical reaction. When the packet and powder inside are exposed to oxygen it reacts by oxidizing.

This brings the oxygen level of the container down to 0.1%. This method is more effective than vacuum sealing (2%) or nitrogen flushing (5%).

How Do I Know if the Oxygen Absorbers are Still Good?

I would not rely on the oxygen indicators. They don’t provide you the information that you need regarding the health of your oxygen absorbers. They only tell you that the oxygen level in the package is below 1%. Remember that a properly prepared container of food with a fresh oxygen absorber added, will bring the oxygen level down to 0.1%.

Beware of Buying Oxygen Absorbers on EBay and Amazon

People who want to have a business reselling oxygen absorbers just need to buy oxygen absorbers in bulk, repackage and resell to end users in smaller bags of 10 or 25 or 50.

You do not know if these individual sellers are handling the oxygen absorbers correctly in the re-packaging process. If they are adding oxygen indicators, the oxygen absorbers may be spent, but if the oxygen absorbers have a little bit of power, the indicator will give the false impression that they oxygen absorbers are still good. Therefore, do not rely on an oxygen indicator to tell you if your oxygen absorbers are good

Where To Buy Oxygen Absorbers

I buy my oxygen absorbers from Discount Mylar Bags or Harvest Right.

How Can You Tell if your Oxygen Absorber is Good or Not?

  • When you take a fresh oxygen absorber out of the package, pinch it. It should feel soft and powdery. As the packet absorbs energy, there is a chemical reaction that causes the powdery iron inside to become crunchy and hard. Eventually the powder will become a single solid piece.
  • Absorbers begin to get warm as you work with them. If you leave a pile of oxygen absorbers in the open plastic bag, you may see condensation developing in the bag due to the warm oxygen absorber. This is not good!

How Do You Use Oxygen Absorbers?

Have the freeze dried food ready, in Mylar bags or mason jars, ready for the oxygen absorbers before opening the sealed package of oxygen absorbers. Take out the number of oxygen absorbers needed for your batch. There are two ways to store the opened bag of oxygen absorbers:

  1. Put the unused oxygen absorbers in a mason jar with a lid. You will see the lid gets sucked down and seals the jar. Be careful to inspect your jars and lids that you use for storing oxygen absorbers. Look for tiny cracks and chips around the rim, especially when reusing jars. I have seen antique canning jars spoil a batch of oxygen absorbers because the jar opening had some defects that prevented a perfect seal.
  2. Keep the unused oxygen absorbers in the plastic pouch they came in and reseal with an appropriate sealer, or transfer to a Mylar bag and use the heat sealer. Or if you are nervous, you can do all three! Seal the oxygen absorbers back in their original plastic, seal that in a Mylar bag and put the whole thing in a mason jar. That is overkill, for sure, but I understand!

How many oxygen absorbers are used?

I found this chart from Homestead and Prepper website. Currently I only use mylar bags that are one gallon or smaller and use 300cc absorbers.

14″ x 20″ (2 gal)10001500-2000
14″ x 18″ x 6″ (2 gal)10001500-2000
12″ x 18″ (1.5 gal)500-8001000-1200
12″ x 16″ x 6″ (1.5 gal)500-8001000-1200
10″ x 14″ (1 gal)300-400400
10″ x 14″ x 4″ (1 gal)300-400400
8″ x 12″ (1/2 gal)100-200200-400
8″ x 12″ x 4″ (1/2 gal)100-200200-400
6″ x 10″ (1/4 gal)100100-200
6″ x 8″ x 2″ (1/4 gal)100100-200

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