Kept at room temperature in an airtight container or in the original packaging placed inside a zip-top bag, most flours will last 6 to 12 months. The exception is whole grain flours: The bran and germ portions of the grain contain oils that cause these flours to go rancid more quickly. Keep whole wheat flour in your fridge or freezer, sealed the same as you would for the pantry, and it will last up to a year. Other whole grain flours such as buckwheat, oat and rice flours will last only two to three months in the freezer. Don't let them go bad: Try them in one of these delicious recipes from Good to the Grain author Kim Boyce.