Have you ever pulled a two-year-old bag of flour out of the cupboard and wondered if it was still good to use? As a recipe developer, I go through a bag of flour every couple of weeks, so I wondered how long does flour last and how the heck do I store it? Is there any way to know when it's gone bad? "I advise people to remember that flour is perishable — it's not salt, it's not sugar, and it's definitely not inert. Take care of it," says Martin Philip, an award-winning author, baker, and baking ambassador for the King Arthur Baking Company. Taking a closer look at different types of flour the grains themselves will help give us the answers.
Types of flour
All whole grain kernels are comprised of three parts: the bran, the endosperm, and the germ. The bran is the outer shell, the endosperm contains starch and protein, and the germ carries the genetic information of the grain and fat. That fat turns rancid over time, which is why some types of flour are best kept cold, while others are stable at room temperature.
White flour
White flour including all-purpose flour, pastry flour, bread flour, and cake flour use only the endosperm of the wheat kernel — which has no oils in it — and don't require cold storage like other types of flour such as whole wheat or rye. Frank Tegetoff, a research and development specialist from the King Arthur Baking Company, recommends transferring the flour from its original paper bag to an airtight container, which will help keep out moisture and bugs. Whether your container is glass or plastic is up to you — just make sure the lid is closed tightly. Store the container in a cool, dry, and dark spot like a cupboard or pantry for up to one year.
Whole wheat flour
Whole wheat flour uses the entire wheat kernel — including the bran and the germ. The germ contains a little bit of fat which, when exposed to oxygen, can go rancid over time. "Freezing slows that process," said Philip. While whole wheat flour can last up to several months in the pantry or on the counter, its shelf life varies based on factors such as temperature, humidity, and its age. Storing whole wheat flour in an airtight container or sturdy resealable plastic bag (Philip recommends double bagging) in the freezer will ensure that your flour lasts through its expiration date.
Rye and other whole grain flours
The same storage rules also apply to rye and all other whole grain flours. Keep them in an airtight container in the freezer. And label them clearly, especially if you're storing more than one type of flour.
Gluten-free flours
Gluten free flours can be subdivided into white and whole grain types.
White gluten-free flours include white rice flour, tapioca flour, and potato flour. These flours are made up almost entirely of starch and contain no fats. If kept relatively cool and dry, these flours have an almost indefinite shelf life. Store these at room temperature in airtight containers.
Whole grain gluten-free flours include brown rice flour, sorghum flour, amaranth flour, and oat flours. These should be stored like other whole grain flours — in airtight containers in the freezer, where they will last for at least one year. Like all other whole grains, these contain fat that can go rancid over time at room temperature.
Polenta, cornmeal, grits, and masa harina
Polenta, cornmeal, and any flour or meal made from corn kernels are best kept cold — preferably in the freezer. This is especially important for any corn product labeled "stone ground" or "whole grain," as these will contain the germ of the corn kernel. Degerminated corn products, which make up the majority of big brand cornmeal and polenta, are technically shelf stable for up to a year, but experts agree that the freezer will keep them fresher tasting for longer.
Nut flours
At this point, we know that fat, when exposed to the air, can quickly go rancid. "A whole nut is nature's perfect storage system," said Tegetoff. "The more we make it easy to use and enjoy (shelled, chopped, ground), the more we take away it's natural protection and hasten its demise. With each refinement more and more of the oils are exposed to oxidation." Storing your nut flours in the freezer will help stave off rancidity and oxidation at least through their expiration date.
Baking mixes
"With this type of mix, the goal is to prohibit the activation of the leavener(s)," Tegetoff said. Once opened, any leaveners in a baking mix such as baking powder or baking soda need to be kept cool and dry in order to retain their full power. He suggests transferring baking mixes into airtight containers or even resealable plastic bags and storing them in a cool dry place (the pantry is fine) out of direct sunlight.
Whole grains and home-milled flour
Milling flour at home has become more popular since the sourdough boom, and home-sized mills produced by brands like Mockmill are gaining popularity. But how long does home-milled flour last and how should you store it?
"Use it, don't store it," said Dr. Stephen Jones, a professor and director of the Bread Lab, an extension of Washington State University. If you have the luxury of an at-home grain mill, you'll reap the most benefits by using fresh-milled flour sooner rather than later. If you need to store it, allow it to cool down before placing it into an airtight container. If you don't plan on using it within a few days, store it in the freezer.
Unmilled whole grains will keep for much longer, as the germ is securely protected by the outer bran layer. Store whole grains in an airtight container in a cool dry place for up to 5 years or in the freezer indefinitely. Dr. Jones emphasized that the most important thing with whole grains is making sure they are clean, dry, and free of bugs before you seal them up for long-term storage.
How to tell if flour has gone bad
Worried about that bag of whole wheat flour sitting in your pantry? The best way to tell if it's gone off is to give it a sniff. "If the flour has gone rancid [or] oxidized, it will smell like Playdoh," Tegetoff said. "The rancid aroma and flavor will transfer through to the finished product. It will not be servable."
There are all sorts of high-tech products that can help keep dry goods fresh for longer such as mylar bags and oxygen absorbers. But flour doesn't need to be vacuum sealed in order to stay fresh — all you need is a freezer to keep flour tasting its best. Better yet, purchase smaller quantities of flour if you don't bake much.
Buy what you need, then buy more — you'll end up with more space in your pantry or freezer and you'll benefit from eating fresher flour.
Shop Food52's storage essentials
Glass Jars with Hand-Turned Wooden Lids
Those paper bags of flour from the grocery store are not packaged for long term storage — when you get home, transfer the contents to a tightly sealed container to keep bugs, moisture, and air at bay. These jars are a stylish way to store flour, sugars, and other dry baking essentials. The hand-turned wooden lid twists on for an airtight seal.
OXO 8-Piece Baking Essentials POP Container Set
This eight-piece set of food storage containers are perfect for holding flour, sugar, and other dry goods. The lids pop on for an airtight seal and the set includes two scoops and a brown sugar saver. Plus, the containers stack neatly on top of each other to keep your pantry clean and organized.
Ultimate 7-Piece Nested Storage Bowl Set
Freezing pantry staples will definitely help them last longer, but not all containers fare well in the freezer. Confidently store whole grain flours in these freezer-safe, airtight containers. This seven-piece set comes with a variety of sizes and are perfect for leftovers and lunches in addition to your dry goods.
