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Dry Canning Using Oxygen Absorbers

Canning your dry ingredients with oxygen absorbers is one of the easiest and quickest ways to preserve your food for short-term or long-term storage.  What’s especially nice about using this canning method is that you can open up the jar anytime you want, use some of the contents, close the lid leaving the oxygen absorber(s) inside and it will reseal itself!  But before we get started lets learn a few things about oxygen absorbers.

About oxygen absorbers:

Oxygen absorbers are small packets that contain iron powder.  The packages have tiny holes in them which allow oxygen and moisture to enter causing a chemical reaction that turns the iron powder to rust.  Once all of the iron powder is oxidized the oxygen absorbers become “loaded or full” the absorbing action stops.  The iron powder cannot escape the packet so they are perfectly safe to use for food preservation.  Once you open the sealed container and the oxygen absorber is exposed to the air, they are reactivated the chemical reaction starts all over again.

Oxygen absorbers come in different sizes and are rated in cc’s (cubic centimeters) which is the amount of oxygen that they can absorb. Typically these packets are sold in sizes that range from 50cc to 2000cc.  The size and amount of oxygen absorbers you will need will vary depending on the size of container or jar that you are using, the head space (the space between the top of your food and the top of the jar) and the amount of air surrounding the pieces of dried food in the container.  We’ll explain the calculation process in more detail below.  Oxygen absorbers can be used multiple times, however, they do have a certain lifespan which will vary depending on how many times they have been activated and deactivated.

It is recommended that you DO NOT remove the oxygen absorbers from their original container or packaging until you are ready to use them.  Additionally, you shouldn’t leave them out in the open for any more than 20 minutes otherwise their lifespan will be decreased and/or they may be rendered useless.

Preparing and filling your jars:washing-jars

Below are the steps you should take in preparation for canning your dry food ingredients:

  1. Just as in other canning methods you should always wash your jars and lids thoroughly.
  2. Check your lids/seals to make sure they are in good shape and not dried out, brittle or cracked.  If you find any that are questionable simply replace them.  If you purchased new lids you can boil them for a few minutes to help soften the rubber seal.
  3. Make sure that your jars are completely dry as you don’t want ANY moisture to remain inside of the jar.  Any added moisture can spoil your dry ingredients and even cause botulism poisoning.  An important note about food that has moisture inside can be found below.
  4. Once your jars are completely dry place them in an “assembly” line on your counter.
  5. Fill each of the jars with your desired dry food ingredients leaving a space of at least 3/4″ to 1″ from the top of the jar.  This will allow for plenty of head space to insert the oxygen absorber packet(s).
  6. Wipe off the rim of each jar to make sure there they are clean and free of debris as this can prevent the lid from sealing properly.

dry-canning-1Determining what size and how many oxygen absorbers you’ll need:

Now that your jars are filled with your dry ingredients you are ready for the second part of this canning process. As a general rule of thumb and to help you get started even faster, a 300cc oxygen absorber is sufficient to seal a standard 500ml mason/canning jar.  I personally use 500cc packets as they aren’t expensive anyway and was the smallest size I could find locally.  Remember that it’s okay to use more oxygen absorbers than what you actually need.

If you don’t want to go through the hassle of converting all of these numbers you can go by some of the examples below:

  1. 50cc oxygen absorbers – Use one for each quart or pint size canning jar. You can also use a number of these in a larger container.
  2. 300cc oxygen absorbers – Use one for each #10 can, gallon or ½ gallon canning jar or equivalent size
  3. 500cc oxygen absorbers – Use 2 packets per 5 gallon bucket of wheat, rice, whole oats and other items that do not have a high residual air volume. It is OK to use 1 of the 2000 cc size oxygen absorber with these grains as well.
  4. 2000cc oxygen absorbers – For food such as pasta with a high residual air volume, you want to use this size oxygen absorber. Use one per 5 or 6 gallon bucket. Will also work fine for wheat, rice, oats, etc.

For those of you who are all about numbers and want to be more precise, you can use the steps below to determine exactly how many oxygen absorber packets you’ll need.  The method below is fairly simple and uses common weight and volume measurements.

  1. Determine the cubic centimeter volume of your container.  The easiest way to do this is to convert the volume of your container into milliliters (ml).  1 milliliter (ml) = 1 cubic centimeter (cc).
  2. Weigh your container (in grams) then add your food product and weigh them together.  Subtract the weight of your container from the weight of your food.  This will give you the net weight of your food.
  3. Subtract the cubic centimeter volume (found in Step 1) from the net gram weight of your food (found in Step 2)  to determine the head space and void space, or residual air volume.
  4. Since there is approximately 21.0% oxygen in air, multiply the residual air volume (found in Step 3) by .21 to get the cubic centimeter volume of oxygen in your product container.
  5. Divide the cubic centimeter volume of oxygen of your container (found in Step 4) by the cc size of oxygen absorbers you are planning to use.  This will give you the total amount of oxygen absorber packets that you’ll need in order to seal your container successfully and preserve your food.  Always round up your numbers. Example: If you ended up with 1.3 packets, then you would use two packets.

Now that you have figured out the amount of oxygen absorbers you need you can follow the simple and quick steps below to finish the canning process:

  1. Open the package or container that your oxygen absorbers came in.
  2. Quickly insert the correct number of oxygen absorber packets into the head space in your canning jars, place the sealing lid on top of the jar and snugly screw on the cap. Don’t over tighten it right now.
  3. Immediately place any remaining oxygen absorbers into a spare mason/canning jar, cover it with a sealing lid and screw on the right tightly.  They will seal the jar and deactivate themselves allowing you to keep them for future use.
  4. Put your jars aside and leave them alone.  DO NOT push down on the sealing lids while the sealing process is taking place.  It can take upwards of 4 hours until all of the oxygen and moisture is absorbed in the jar.  As a general rule of thumb you should leave your jars sit overnight and check them the next day.

With a proper seal the center of the lid should already be pushed downwards into the jar.  You shouldn’t be able to push it down with your finger.  Also, you shouldn’t be able to easily pull off the lid with the tips of your fingers.  If your jar didn’t seal overnight the rim of the jar or sealing lid may not have been cleaned properly or the rubber seal may be damaged.  If this has happened the oxygen absorber(s) in your jar will no longer be any good. Throw them out and replace them with the fresh ones that you put in your spare canning jar and let the sealing process repeat- again making sure there is no debris on the new lid and on the rim of your jar.  Once you are confident that your jar is sealed you can completely tighten the sealing ring.

Preserving different dried food products:dry-canning-2

You can preserve many types of dried food products, however, you need to make sure that the food you are canning contains less than 10% moisture and is low in oil content.  If the moisture level is greater than 10% you run a risk of botulism poisoning.  Below are a few examples of dried food products below that you are able to safely can with oxygen absorbers.  The approximate shelf life of these food items is based on the food being stored at a stable temperature of 70 Fahrenheit.  Some of these can store even longer if kept in cooler temperatures and dark places.

  • Beans – Approx 8-10 years
  • Dehydrated vegetables – Approx 8-10 years
  • Dehydrated fruit – Approx 5 years
  • Dehydrated dairy products – Approx 15 years
  • Flours and other products made from cracked/ground seed – Approx 5 years
  • Garden Seeds – Approx 4 years
  • Hard Grains (buckwheat, corn, flax, kamut, millet, hard red wheat, durum wheat, hard white wheat, soft wheat, special bake wheat, etc) – Approx 10-12 years
  • Salt and sugar – These should last indefinitely
  • Pasta – Approx 8-10 years
  • Peanut butter powder – Approx 4-5 years
  • Rice (brown) – Approx 1-2 years
  • Rice (white) – Approx 8-10 years
  • Soft Grains (barley, oats, groats, quinoa, rye, etc) – Approx 8 years

Keep in mind that some foods shouldn’t be stored with oxygen absorbers. Items such as sugar and other granulated food items can be stored in this fashion but they will clump together and turn into solid masses.  The reason behind this is because these foods need a certain amount of moisture in their environment in order to maintain their powder-like form.

So before you start any project that involves food it’s important that you do your research. I hope this article has helped you and we’d love to hear about your dry canning experiences!

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