For most bakers out there, flour is the foundation for all treats and the answer to our questions. Whether you're using all-purpose, whole wheat, spelt, or coconut flour, it's important to be aware of what you're working with. The last thing a baker wants is to make gluten-free cookies with rancid almond flour or use cake flour that has a funky aftertaste. Buying flour of any kind on a whim is common, but if you bake a cake once a year and tuck away your flour until the next time you get inspired, you must be asking, "Does flour expire?"

Anybody who does some light cooking or baking routinely uses flour, so it’s crucial to know if the powder could possibly make you (or the people you're cooking for) sick. After all, there is nothing worse than having perfectly softened butter to find out you need to run to the store to get more flour. Here is the low-down on the question "Does flour expire?" (even if it’s four years out of date) and when to toss it.

So, does flour expire?

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Casey Irwin

Long story short, yes. If your flour is really expired, the molecular structure of the powder changes and can potentially produce harmful compounds. But like many other foods, flour will remain good long past its "best by" or "better if used by" date that can be found on the original container. The key is knowing when flour has actually become rancid.

According to Healthline, the type of flour can drastically change its shelf life. Regular flour tends to last 6-8 months past its printed date, while whole wheat flour is typically only best for an extra 4-6 months. It’s important to pay close attention to how long past the "best by" date your flour has gone so you don't have to make a random guess.

How can you tell flour has gone rancid?

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Jocelyn Hsu

This answer is a bit trickier and can be determined by smelling or tasting the flour. If the flour smells musty or sour, then it’s probably expired and well past its “best by” date. An unpleasant taste or smell means it’s time to part ways and toss your flour.

Another threat to the longevity of flour is if it comes into contact with water or moisture. If this happens, the flour might develop moldy clumps and a foul smell. 

Can I still use flour after it expires? 

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Jocelyn Hsu

The time between fresh flour and rancid flour is precious. Personal preference comes into play here. Consider taste testing a pinch of flour to make sure that it tastes normal, as the taste will change before a change in smell is noticeable. 

If the smell and taste is not rancid (stale, musty, or sour), then there is really no reason to toss flour. Also take a look at the color, as it should not change. The outcome of the product, if you are baking or cooking, should not be strongly affected by the "best by" date.

If your flour has formed mold, toss it immediately because mold can be toxic if consumed. 

Can expired flour make you sick?

While eating anything expired is risky, there are no concrete studies that prove expired flour is detrimental to health. Worst case scenario is that your cake or breaded chicken tastes and smells funky.

However, consuming moldy flour that's been exposed to moisture has some serious risks. According to Healthline, toxic molds, which could potentially form in moist flour, can cause upset stomach, vomiting, and/or diarrhea

How can I keep flour fresh?

Victoria Guo

One of the worst things you can do for your flour is leaving it out in the open in that punctured bag you struggled to get open in the first place. That exposes the flour to unwanted heat and moisture. 

In general, the FDA recommends that shelf-stable foods, like flour, be stored in dry, cool cabinets. If the original container is still intact, keep the flour there. One way to ward off the question, "Does flour expire?" is using additional sealing with a plastic bag.

One of the easiest and best-looking ways to keep most ingredients fresh is to invest in a countertop jar that can hold a number of products. They're often sold with their different labels for flour or sugar, but more importantly, they seal off any air or moisture to keep the product inside fresh. Added bonus, they look great on any countertop.