Flour is a pantry staple made by grinding grains or other foods into powder. Although it traditionally comes from wheat, numerous types of flour are now available, including coconut, almond, and other gluten-free varieties. Many people keep flour in their pantry for long periods of time, even well past the expiration date. But, things can easily go wrong if you don't know the telltale signs of spoilage and have a fail-safe storage method that ensures freshness during such long periods.
According to the United States Department of Agricultural (USDA), flour is considered shelf-stable. This means that flour can be safely stored at room temperature. Yet, it should be kept in an airtight container in a cool, dry place to preserve its freshness. Refrigerating or freezing it may further increase its shelf life. For instance, multi-purpose flour lasts 6–8 months on the shelf but up to 1 year if refrigerated and two years if frozen.
Keep these tips in mind while storing your flour:
Flour’s shelf life depends both on the type of flour and the storage techniques you use. For example, white flour lasts longer than whole-wheat and alternative varieties due to its lower fat content.
Most packaged flours have expiration dates — also called best-by dates — printed on the bag to indicate how long they’ll stay fresh. However, these labels aren’t mandatory and don’t denote safety. Thus, your flour may still be safe to eat even after the best-by date. The best way to determine whether your flour is safe is to smell it. While fresh flour has a neutral odor, bad flour smells off — it can be stale, musty, or almost sour. It may also look discolored.
Additionally, if your flour has come into contact with water or moisture, large clumps of mold may appear. In this case, you should immediately discard the entire bag. Try creative ways to use your old flour when it’s near or past its expiration date to prevent food waste. Aside from baked goods like bread and cakes, it’s also suitable for creating non-food items like playdough or homemade glue.
When flour goes rancid, its molecular structure changes, producing harmful compounds. However, no recent studies have revealed any detrimental effects of eating sour flour. Although cooked foods made with it may taste unpleasant, they’re unlikely to harm your health if consumed in small amounts. On the other hand, moldy flour can be dangerous and foul-tasting. While not all molds are harmful, some can produce hazardous chemicals known as mycotoxins.
These compounds can trigger symptoms like vomiting and diarrhea. Mycotoxins are also linked to other serious illnesses, including cancer and liver disease, depending on the amount eaten and duration of exposure.
Thus, it’s always best to throw out your flour if it smells terrible or shows signs of mold.