Oxygen Absorbers

 As noted previously, sometimes bad things happen with stored food over time.  Food in a sealed container that has oxygen in it, as well, can suffer from infestation and oxidation / deterioration. Freezer burn is another example of this.  So it is best when storing things for more than a short time to vacate the oxygen.

Food Saver-style vacuum sealers do this, and there are also jar attachments for wide mouth and regular mouth canning jars.  I don't know offhand what concentration of oxygen they can reduce the interior of a jar to, but they're a decent approach. They may not drop it enough to prevent insect eggs from hatching.

Another approach is to use oxygen absorbers. They are sold in various sizes to accommodate different containers.  US Emergency Supply has a very useful chart on this. In addition to canning jars, mylar bags and buckets can be used (the bags do not need to be kept in a bucket, but a bucket needs a bag in order to store food--BYU researchers found that oxygen levels could not be reliably maintained at a low enough level using a bucket alone, probably because of seal leakage).

There are plenty of resources online showing the use of mylar bags.  In addition to oxygen absorbers, dry ice can be used to drive out the oxygen.  That's a more old-school approach that fills the container with CO2 rather than sucking the oxygen out of the air and into the iron powder in the absorber.  The Rose Red Homestead has a video that demonstrates both approaches.

When exposed to air, oxygen absorbers begin to react.  It does not necessarily happen very fast, but it does happen: so opening a package of them doesn't render them all useless within two minutes unless sealed back up, but they do need to be put in either their final destination or in another airtight container quickly (a canning jar that is then vacuum-sealed is ideal).

Some oxygen absorber packages have an oxygen indicator:

The Oxyeye is pink when it hasn't been exposed to oxygen, and it soon turns purple after opening the package (or after the package leaks and allows the concentration inside to exceed 0.05%).

One caveat is that in time, the indicator will turn a faded pink, looking almost like it did when unexposed:

The above indicator is a few months old; I just clipped it to the refrigerator to see what would happen.

A usable oxygen indicator will feel like a pillow stuffed with powder, which it is when it's in its unexposed state. If it feels rigid and crumbly, it's probably no longer able to absorb oxygen.  Some vendors repackage absorbers into smaller quantities.  The repackaged absorbers are quite likely to be at least partially depleted in this process, and may be completely ruined. While some oxygen reduction is better than none, levels have to drop below one percent to prevent insect eggs from hatching.  With functioning absorbers and mylar bags, this is achievable.

The above picture shows some pinto beans, packed into gallon-sized mylar bags (five pounds in each). After a day, a noticeable vacuum effect has sucked the package down around the contents as the oxygen has been removed.

After my infestation episode, I'm trying to put my wheat into mylar, even though wheat doesn't necessarily need oxygen-free storage for quality purposes over a relatively short time frame. Hopefully the day of weevils will not be repeated.