How and When to Use Oxygen Absorbers

Food Storage Made Fabulous, the 2nd volume of articles from the Prep School Daily blog, is now available on Amazon.  With over 100 family-friendly recipes using basic long-term food storage staples, your family will have no idea there's a crisis. 

 

Today it's all about oxygen absorbers, those white packets you sometimes find in food you got from the grocery store and that every respectable prepper adds to their buckets and bags and jars of food they store at home.  Most understand that oxygen absorbers help preserve their food, but confusion arises as to the limitations of what these little wonders can and can't do and what size packet for what size job.

What they are:  The purpose of oxygen absorbers is to help maintain freshness, taste, and quality in dry foods as well as protect them from insects. They only work in sealed containers or packages.  Oxygen absorbers are available through Amazon, Home Storage Centers (in person or online), and grocery stores like WinCo. 

How they work:  Oxygen absorbers are little packets that contain iron, sodium, and activated carbon.  The iron does the vast majority of the work here; the porous packet material allows the iron to absorb oxygen and moisture from the air in the container but does not let any of the iron leak out.  The sodium activates the iron, and the activated carbon absorbs gases and odors.  Hand warmers, which some prepper websites advocate as a substitute for oxygen absorbers because they also contain iron powder, sodium, and activated carbon, are not food safe.  They also contain vermiculite and may have traces of asbestos, not necessarily something you want right next to your food.  And even if they were food-safe, there is no way of calculating how much oxygen they absorb.  Would one hand warmer be sufficient?  Hand warmers may work well for killing wool moths when storing your sweaters and blankets away for the summer.

What foods they are used with:  Foods should be low in moisture, 10 percent or less.  If the moisture content is not low enough, the conditions will be ripe for the growth of the bacteria that causes botulism, and instead of being happy that you have food, you will be wishing you were dead and then you will be dead.  

Oxygen absorbers are used for:

• grains and grain products (flours and pastas)
• beans
• nuts
• chocolate
• herbs and spices
• dehydrated fruits and vegetables
• pharmaceuticals
• processed, smoked, cured meats and cheeses
• dry milk products

Do NOT use oxygen absorbers with:

• sugar (If you do, the sugar will still be plenty safe to eat, but you will need a cheese grater or a hammer to use it.  Oxygen absorbers turn sugar into rock solid bricks.)
• pancake mixes
• yeast
• baking soda
• baking powder
• salt  

Containers they can be used with:   

• Mylar bags
• Soda bottles (PETE bottles with airtight, screw-on caps.  Milk jugs should not be used.)
• Canning jars with gasketed metal lids or the re-usable canning lids, like those produced by Tattler
• Plastic buckets with a gasketed lid

What size oxygen absorber for what size container? There are actually quite a few variables that affect the capacity of the oxygen absorber needed--the volume of the container, the density of the food, and your altitude.  Most guidelines provide only for the volume of the container and assume that grains and flours are being stored, and that is what is provided in the chart below.  However, if you are storing items that are less dense or have more air, like beans, pasta, and freeze-dried meals, you need double the number of cc's in your oxygen absorber.  For example, if you would use a 1500 cc absorber (or the equivalent amount in smaller absorbers) for a five-gallon bucket of wheat, you would need two of these 1500 cc absorbers for the same bucket of beans or pasta.  

However, just to keep things interesting, if you live at a higher altitude, above 4,000 feet, you need fewer oxygen absorbers, or less oxygen absorber capacity, I should say.  So if you would normally use five 300-cc absorbers for a five-gallon bucket, if you were at high altitude you would only need four.  Yes, the math doesn't work out perfectly because we are limited in the selection of cc absorbers.  And it is always better to have more cc's than is required. 

              100 cc absorber                            1 quart jar or 1 liter bottle

              100 cc absorber (2)                      1/2 gallon jar or mylar bag

              300 cc absorber                            1 gallon container or #10 can

              500 cc absorber                            1 gallon bag

            1000 cc absorber                            2 gallon mylar bag

            1500 cc absorber                            5 gallon bucket

            2000 cc absorber                            6 gallon bucket

And an anecdotal tidbit for those living at higher altitudes.  Back in my beginning food storage days, over thirty years ago now, when I lived at Lake Tahoe, there was a woman who had lived there for at least ten years at the time.  She was very good about using and rotating her long-term storage items.  She kept her food in plastic buckets and never used anything to protect it from bugs and attributed it all to the high altitude.  (She was at 7,500 feet.  I was at 6,500 feet and never noticed a problem, either, but I wasn't there as long.)  It may also be a factor of the lack of humidity.  FWIW.  However, this only has to do with bug infestations.  You'd still want to use oxygen absorbers at high altitudes to preserve freshness.

How do you use oxygen absorbers?  First, calculate how many you need for each container, taking into account the volume of the container and density of the food, and if applicable, your altitude.  Have all your buckets, bags, and jars filled and ready to be sealed.  Remove as many absorbers as you will use in the next 15-30 minutes and spread them out on a tray so that they do not touch one another.  Place the remaining absorbers in the smallest canning jar that will hold all of them and fill it in with uncooked rice.  Replace the canning lid and band and vacuum seal as well, if possible.  A one-pint jar will hold about 25 absorbers.

Put the oxygen absorber(s) on top of the food and seal the container.  While bags may shrink around the food as the oxygen is absorbed (this usually takes a few days), all the gas does not need to be removed for the food to be preserved.  Remember, these are oxygen absorbers.  The nitrogen, which makes up almost 80 percent of our air, remains in the bag.

 

Is using an oxygen absorber the same as vacuum packaging? Actually, no.  Oxygen absorbers are more efficient at removing oxygen than vacuum packaging.  The gas that remains in the package is only nitrogen, which will not affect the food nor permit the growth of bugs.  But you can always combine both methods to provide an additional layer of protection if that makes you feel better.  There's no harm in it, unless you are using Mylar bags and anything that will poke holes in the Mylar, like rice.  Then it's best to skip the vacuum sealing.

 
For more information:

https://www.sorbentsystems.com/Oxygen_Absorber_Facts.pdf

https://www.usaemergencysupply.com/information-center/packing-your-own-food-storage/oxygen-absorbers-recommended-amounts
https://www.familysurvivalplanning.com/using-oxygen-absorbers.html
https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=1089&context=facpub

 20 june 2019