Does Flour Go Bad?
Buying a lifetime-supply-size bag of bread flour might seem like a good idea, but can you really bake enough sourdough to use all that flour before it expires? Wait, flour goes bad? Indeed, and faster than you might think. Read on for everything you need to know about the shelf life of flour, including how it varies from flour to flour, the best way to store flour, and what happens if you do use past-its-prime flour.
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What is the shelf life of flour?
How long flour stays fresh depends on the type of flour, as well as how you store it.
Refined flours
All-purpose flour, white bread flour, white cake flour, white pastry flour, white self-rising flour and other white, starch-based flours like potato and tapioca flours are refined flours and have the longest shelf life. Depending on the storage method (more on that later), these refined flours will keep at least six to eight months and even up to two years.
Whole-wheat flours
The whole-wheat category includes white whole-wheat flour, pumpernickel flour, whole and medium rye flour, buckwheat flour and any whole-grain flour blends. These flours have a much shorter shelf life than refined flours because whole-wheat flours contain the grain's bran and germ (meaning they've been refined or processed less), which are rich in fiber, nutrients and oils that spoil faster and are more sensitive to light, moisture and air. Depending on how they're stored, whole-wheat flours will keep for three months to a year.
Nut flours
Almond, coconut and other nut flours contain nut oils that make them spoil faster than wheat-based flours. Most will keep for three to six months, depending on storage.
Gluten-free flours and gluten-free flour blends
These flours and flour blends often contain nut or root flours, which makes them quicker to spoil, so you can expect them to last three to six months, depending on storage.
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How to store flour so it lasts
All flour should be stored in sealed, airtight containers in a cool, dry and dark place to preserve freshness. If transferring a bag of flour to a container, you may want to note the best-by date, either by marking your container or by cutting off that part of the bag and adding it to the container. To extend the shelf life of flour, store it in the fridge or freezer, but make sure that it's wrapped airtight—preferably using a double layer of freezer bags—to keep out air and moisture, as well as odors and flavors from nearby food.
If wrapped and stored properly, refined flours will keep for six to eight months at room temperature, up to one year in the fridge and up to two years in the freezer. Whole-wheat flours will keep for three months at room temperature and up to a year in the fridge or freezer. Nut flours will keep about three months at room temperature and up to six months in the fridge or freezer, though they're one of the most delicate, which is why many cooks insist on only storing them in the fridge or freezer. Gluten-free flours vary depending on their ingredient mix, but their shelf life will likely be similar to that of whole-wheat or nut flours.
Choosing a storage method depends not just on the flour but also on how often you plan to use it. If you mostly use all-purpose flour and do so quite regularly, keeping it in an airtight canister in your pantry makes sense. However, if you are only an occasional baker and like to use whole-wheat flours, nut flours and gluten-free flours, you should consider storing them in the fridge or freezer because they spoil more easily and you're not baking often enough to use them up quickly.
If you do opt for cold storage, you may want to give the flour time to come to room temperature. Flour warms up quickly and its temperature most likely won't make a difference in your average cookie or brownie recipe, but for some more sensitive recipes, including many bread recipes, it's important to use room-temperature flour.
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How can you tell if flour has gone bad?
The most obvious way to tell if flour has gone bad is to check the expiration date on the bag. But if you moved it to an airtight container—as you should—and ignored the aforementioned advice to note the best-by date, you might not know it. And, as discussed, how you store your flour will affect its shelf life.
The best approach is to check the flour yourself, and you should start by looking at it. Mold, lumps and bugs are obvious red flags, but flour should also have the same color and consistency it had when you purchased it.
Smell is another great test. Wheat-based flours should smell neutral or almost not at all, but you may detect a subtle wheat aroma. Nut-based flours will smell nutty. If flour smells unpleasant in any way—sour, moldy, musty, bitter—it's gone bad.
To learn the signs of spoiled flour, it's good to start paying more attention to fresh flour. The next time you open a bag of any flour, give it a closer look, and breathe in, so you have a better sense of what it looks like and smells like. Then, a few months down the line, it will be easier to tell if it's still fresh.
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What happens if you use flour that's gone bad or expired?
Putting aside these guidelines, there may be times when you simply don't know if your flour is still fresh. Maybe you tossed the bag with the best by-date or can't tell if it smells sour. Or maybe you just forgot to even check and then you're staring at a basket of muffins wondering if that whole-wheat flour was past its prime.
Rest assured that, most of the time, using expired flour will not make you sick. There is a small risk of ingesting too many mycotoxins—toxic compounds produced by certain kinds of mold—but you'd have to ingest large amounts for them to make you sick, and flour with that much mold would smell so bad you wouldn't want to use it.
The more likely result of using expired flour is that it will affect your baking. If the flour has a bad flavor, it may come through in your cakes or quick breads. It may also change the texture, as flour that's been around too long has likely been exposed to a lot of air, which can damage the protein structure, resulting in more crumbly baked goods. One flour to be particularly careful with is self-rising flour. Even if the flour itself is fine, after time the baking powder may lose its potency and affect the rise of whatever you're baking.
In the unlikely event that you bake with flour containing flour beetles, or weevils, know that while it's incredibly unappetizing, it won't hurt you. The bugs will die in the oven, and you may not even notice them.
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Bottom Line
Flour may be more perishable than you realized, but if you store it properly—in an airtight container, away from heat, light and moisture, and maybe even in the fridge or freezer—and check it before you grab the measuring cup, it will be fresh and ready for your next batch of blondies, banana bread or chocolate chip cookies.
