I just found a huge tin, that I’d filled with flour, 7 years ago. I opened it to take a quick peek...and, it looks just perfect. No evidence of bugs, at all. I’m pretty sure I’d put the flour in the freezer, before I put it in the tin.
Yeah, I don’t think it’s an always guaranteed problem (bugs/larvae) in flour, but it is most definitely a potential issue. Freezing it definitely seems to work, and keeps the worry away more than anything. I’m still working through a big bag of Safale baker’s yeast I bought some years ago. I froze it in a canning jar, and it seems perfectly fine.
One thing I didn’t have much luck with, is the “all in one” stuff like Bisquick. They use powdered fats of somekind or something that can start to turn rancid or oxidize. I didn’t notice that so much, but I did have to goose it with fresh baking powder to make it work. I just threw it out, and make my own bisquits or dumplings or whatever.
Instant Oatmeal, with sugar and flavorings didn’t fare well at all, though to be fair I didn’t do anything to try tonpreserve them. It tasted real strange. I still have a big container of Quaker old fashioned oats, that are quite ancient. I don’t know if they are bad or not. Maybe, the cardboard isn’t airtight or anything. I’ve since bought several and ate through them as normal, they are inexpensive and a good source of protein, for a grain. Thing is, I don’t really like oatmeal. It’s OK, but it is a good stockpile item. Just hope I never need it. Better to stock foods one really likes.
Another interesting problem, I had an unopened can of cocoa powder that had been bouncing around for years in my chuckbox. When I finally rotated it out, it had a slight but definite whang to it - it tasted like my old (long gone) Chevy pickup smelled - the exhaust. It picked up some oil/gas odor from spending a few too many roadtrips in the bed w/topper area, I guess.