You dont have to put grain in the freezer all you have to do is put it in a mylar bag then into a 5 gallon bucket with lid. Then fill with nitrogen from the bottom to the top. Then put on with a twist lid that will be air tight.... no bugs.

Keep in cool dry and no light. This way when the power goes out you dont have worry.

Too add nitrogen to bucket:

Insert the nitrogen tube into the 5 gallon bucket and cautiously push the tube to the bottom of the Five gallon bucket. Care should be taken not to damage the bag with the tube. Now open the nitrogen valve allowing nitrogen into the bag. We're not talking about a lot of gas. Think of a gentle to moderate blowing through a drinking straw, as a guide for how much nitrogen to allow into the bag. Flush the nitrogen while holding the bag vertically. Nitrogen is heavier than air and will settle, forcing the oxygen out the hole at the top, so do not restrict the air from escaping from the bag. The nitrogen gas will be cold so you will feel the bag getting cooler as the nitrogen replaces the oxygen.