We prepared some beans and rice for long-term storage this weekend. We'd purchased a 50-pound bag of each about two weeks ago, and then ordered some mylar storage bags with oxygen absorbers online. The bags came in last week.
The hubster found this tutorial online that shows how to properly seal the bags. One point that doesn't seem to get emphasized enough (at least in my research) is that you don't want to have any wrinkles in the bags when sealing them, as this could make for an air leak.
Most of the tutorials you can find online (on YouTube, for instance) seem to focus on bags large enough to fill a 5-gallon bucket. However, once you open the bag, time is ticking. We opted instead for one-gallon bags. This makes for some extra work, but will be better in the long run. One "gallon" of rice is a LOT of rice for two people, but not so much that we can't eat it before it goes bad or gets infested, as grains are wont to do. I'd be worried we couldn't use up a 5-gallon bucket of rice in time. By using smaller bags, our food storage will last longer. Plus, a one-gallon bag of rice or beans would be a nice bartering tool, if things came to that.
One thing to keep in mind when using oxygen absorbers is that as soon as you open the package, the absorbers are activated. You want to seal them up in the mylar bags ASAP. A good plan is to have all your bags filled and ready for sealing, and your iron on and heated, before you open the absorbers. In our case, we received one package of 50 oxygen absorbers, but we weren't planning on using all 50 of them. We got our bags and iron ready, opened the absorbers, counted out how many we needed, and vacuum-sealed the rest in a Food Saver bag. So far, the absorbers seem to be remaining good (they change color once they're spent).
Mylar bags with oxygen absorbers will protect your food from decay, but not from rodents. That is why most people store their food in mylar bags, inside a bucket. Buckets are cheap (sometimes free--ask at your local grocery store deli/bakery if they have any buckets they could give you) and protect your bags from bugs or rodents that might chew through them. We could have put our one-gallon bags in buckets, but opted instead for a large plastic tote.
One additional change we made was to seal each bag twice. We sealed it the first time using an iron. For a second seal, just in case we left a tiny air hole with the iron, we used the sealing mechanism on the Food Saver machine. Why not use the Food Saver exclusively, you ask? It was a logistics thing. Once the gallon bags were filled, it would have been too difficult to hold the bags at an angle without spilling the contents, and still get a good seal with the Food Saver. If you don't have a Food Saver, you could seal each bag twice with an iron as well--you'd just have to be sure to leave enough room at the top of the bag.
Next, I plan to amass some herbs and spices, and seal those in mylar as well. Another trick I learned online, is to take a one-gallon mylar bag, cut it in half, and reseal the cut half with an iron, creating two, half-gallon bags. These will be a good size for herb storage, I think.