Oxygen Absorbers Info

Hey everyone, this is Tobias.  We get a lot of questions about oxygen absorbers, so I wanted to do a page for easy reference.

What are oxygen absorbers and how do they work?

Oxygen absorbers use a base metal (iron) and a basic chemical reaction (oxidation) to remove and sequester oxygen inside the little packet.  If you open a packet up you will see a dark gray or black substance, which is just powdered iron.  As a packet is used up, the material inside the packet will become a little hard and crunchy, and will turn a reddish brown.

How Do I use Oxygen Absorbers with Mylar Bags?

Each oxygen absorber is rated to absorb a certain amount of oxygen.  They are rated in CC (Cubic Centimeters).  So a 300cc oxygen absorber will remove 300cc (.3 liters) of oxygen from a closed atmosphere container (the mylar bag).  However, because air is about 80% nitrogen, they only need to absorb the 20% remaining that is oxygen.  Based on the 4:1/80:20 ratio, an oxygen absorber will 'clear' an empty space about 5 times it's rating.  So for example, that same 300cc oxygen absorber will clear an empty bag or jar containing as much as 1.5 liters (300cc x 5) of air.

However, because when we use them our bags are mostly full of food, and not air, we can use a higher ratio of oxygen absorber to bag size.  That is why, for example, we estimate a 300cc oxygen absorber can clear a 1-gallon Mylar bag.

How Many Oxygen Absorbers Should I use?

A general rule of thumb is to use 300-500cc of oxygen absorber per gallon of food you are storing.

A little chart on how that works out:

1 Quart Bag - 100cc oxygen absorber

1 Gallon Bag - 1-2 300cc oxygen absorbers

2 Gallon Bag - 2-500cc oxygen absorbers or 1-1000cc oxygen absorber

5 Gallon Bag - 1-2 2000cc oxygen absorbers or 2-3 1000cc oxygen absorbers

My Bag Didn't Contract, are my absorbers bad???

In almost all cases (99.99%), most certainly not!  Our oxygen absorbers are used by food processing companies worldwide, and there is no way they would accept a product that only worked 'some of the time'.  Also, because we sell pallets of oxygen absorbers every month in both retail and wholesale quantities, we are always turning them and have the freshest stock available. 

There are several reasons your bags might not contract.  For example, there are certain types of foods that will almost never contract, such as very dense foods like flour and very fluffy foods like oats.  A second reason bags may not contract is they are only removing the 20% of oxygen we talked about above.  Meaning the bag will always have the 80% nitrogen remaining inside (nitrogen is inert, so that is ok!). In some cases, you can even be storing the same type of food and notice some bags compress and some bags do not.  This can be caused by just a tiny variation in the amount of headspace (air) remaining in each bag.

Also, when using oxygen absorbers with very low moisture content food, they will take longer to activate (this is normal). Where in some cases an oxygen absorber can work in hours, in very arid and dry conditions, it can take up to a week or more to fully remove the oxygen from a container.

Finally, sometimes folks will not use enough oxygen absorbers for what they are storing.  Remember, if you are storing in 5 gallon bags, but buy 100cc oxygen absorbers, you will need to use 20 or more absorbers per bag!