Storing whole-grain flours
Because whole-grain flours contain oils, they can quickly go rancid if not stored properly. Check the sell-by date on the package when you buy them, or if you buy from a bulk bin, smell the flour. It should not have any oily aromas.
Heat and sunlight can spoil the grains, so keep them in a cool, dry cabinet if you intend to use them within a week or two. Cookbook author Lorna Sass advises placing them in a sealed container in the refrigerator or in the freezer, especially in the summer. Pastry chef and author Kim Boyce favors the fridge, saying she detects off-flavors when she stores whole-grain flour in the freezer.
I have had good luck storing them in both the refrigerator and freezer in resealable food-safe plastic bags.
-- Samuel Fromartz