Do you have a bag of flour currently rolled up in your pantry? Same. But it turns out that’s not the best way to extend its shelf life. The USDA considers flour shelf-stable and non-perishable. While refined flours (white flours like bread, AP, cake and self-rising) will stay at peak quality for anywhere from one to two years, air, heat and light exposure will speed up its expiration over time.
Any type of refined flour is better off in an airtight container stored somewhere cool and dark. Use a container with an airtight seal, made of an opaque material that protects against light, like plastic or stainless steel. If you can’t remember how long the flour has been sitting on your shelf, you may want to freeze it for two days to kill any potential weevils (those tiny, pesky pantry bugs) or eggs in the bag before transferring it to a container. You’ll know flour has gone bad if it smells off or sour.
Whole-grain flours can oxidize even faster because they contain more natural oils, so always keep those in the fridge for up to six months or in the freezer for up to a year.