Why Doesn't My Bag of Food with Oxygen Absorber Looked Vacuum Sealed?

 AIR is made up of Nitrogen & Oxygen.

 "Air" is a colorless, odorless, tasteless, gaseous mixture, made up of mainly nitrogen (approximately 78 percent nitrogen) and oxygen (approximately 21 percent oxygen) with approximately 1% of lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases.

 When you put an oxygen absorber of the correct size into a Mylar bag along with food, the oxygen absorber is going to scavenge (aka remove) the oxygen from the bag, nothing else. The bag will still contain all of the nitrogen and 1% other gases, so you will still have 80% of what you were calling "air" inside the bag. What is in the bag is now is nearly 100% nitrogen, which is why this process is nearly identical to the much more complicated method of flushing a bag with nitrogen gas from a big tank.

It will most likely LOOK like you still have "air" (oxygen + nitrogen + 1% other) in the bag because the VOLUME of "air" has only been reduced by 21% (the oxygen). But what is in the bag is NITROGEN, not "air" (oxygen + nitrogen).

The oxygen absorber will remove ALL the oxygen and leave ALL the nitrogen, so the chances of all your Mylar bags of foods looking vacuum sealed is slim. It's just plain physics. If there was a cup of "air" in the bag when you sealed it up with the oxy absorber, then you will have over ¾ of a cup of nitrogen still in that bag after 24 hours, which is exactly what you want.

Occasionally, a mylar bag of dried food with an oxygen absorber of the correct size will appear to be vacuum packed. Vacuum packing is a completely different process than nitrogen packing. Vacuum packing removes most, but not all, of the "air". Vacuum sealing leaves some "air" (nitrogen AND oxygen) in the bag with the food, which is in a clear single layer plastic bag not designed for long term storage (if you are using a Food Saver or Seal a Meal). It is OK if there is still some oxygen in a vacuum sealed bag because vacuum sealing is for short to mid-term food storage, NOT long term food storage.

 

So if your Mylar bags don't suck down hard the way a vacuum sealed bag does, don't worry. What is still in that bag is nitrogen, protecting your food for long term storage.