Milling and Storage

STORING FRESH WHOLE GRAIN FLOUR

It might seem odd that a product that we habitually see sitting on grocery store shelves (for who knows how long) and in the backs of our pantries (also for who knows how long) is actually not as “shelf stable” as we may think. Especially whole wheat flour. Before you throw in the towel about storing whole wheat flour properly, consider that the beauty of whole grain flour – all of the goodness contained in the grain’s outer shell and germ – is precisely what makes it go bad more quickly. And it is what makes a little fussing over storage absolutely worth it. Grain needs to be stored properly to fully appreciate and reap the benefits of its wholesome beauty.

Why does whole-grain flour spoil more quickly?

Whole grain flours are packed with healthy oils [link to nutrition benefits page], making them more nutritious but also less stable than refined flour. Heat, light, and moisture degrade the nutrient content of whole grain flours, which require cold temperature storage to slow the degradation of nutrients, flavor, and taste. While the fat composition of wheat is relatively low (approx. 2-3%), whole wheat flour contains more fat (also known as lipids), than refined flour. The fat distribution within the grain is approximated as follows: 63% in the endosperm, 34% in the germ, and 3% in the bran.23 Unfortunately, wheat grains also contain enzymes that break down these fats, releasing what are called “non-esterified fatty acids,” which can make the flour taste bitter and rancid.24 Some enzymes that degrade fats are more plentiful in the bran and germ, potentially exacerbating lipid oxidation in whole grain flour.25 Oxygen in the environment can also get to the fatty acids and break them down. The breakdown of fats is of concern because it can negatively affect the bake by diminishing gluten’s ability to hold gas and stretch.26 While the breakdown of fat is the main storage concern, changes in proteins and carbohydrates can also occur over time which can affect baking behavior. Vitamin E and carotenoids, which have desirable antioxidant properties, also degrade over time.27 This is to say, all bakers using whole-grain flours should treat fresh flour as a perishable product, using it as soon as it is milled, or freezing it if necessary.

Researchers have been working to develop creative solutions to the short shelf life of whole-grain flour. Attempts to stabilize lipids have included: incorporation of additional antioxidants or metal ions into flour, limiting oxygen, heating, and gamma irradiation.28 These approaches haven’t been super successful, but the good news is there are a few simple and low-tech solutions to keep your whole grain flour fresh, detailed in the next section.

Purchasing and storing your fresh whole milled flour

We encourage you to get the freshest flour possible to maximize nutritional benefits and flavor. Unfortunately, as Jonathan Stevens of Hungry Ghost Bread in Northampton, MA laments, “The problem with almost all the whole wheat flour that you can get in the store is that it’s rancid already, and you won’t really know that until you try to make a loaf of bread and it just doesn’t perform right, it doesn’t taste quite special. And you blame yourself.” Luckily, he says, “now we’ve got a whole renaissance of local mills” and the technology for home mills is becoming more accessible. Below, we offer tips on how to source the freshest whole grain flour, and if you need to purchase from the grocery store, we’ll tell you how to maximize the freshness of that flour, too.
Option A. Buy locally milled flour. 
Visit your local mill or store that stocks freshly milled whole-grain flour or whole grains that they can mill for you. If this option is available to you, we highly recommend it – it allows you to support local growers, millers, and/or store owners, feel more connected with your food, and guarantee freshness. The internet is your friend when it comes to hunting down local mills!

How to buy: Check out our New England Mills [link to that section] guide to find a mill or store close to you. If there is not a location close to you, some will ship to you, but still try to buy as locally as possible to minimize shipping costs and time.

How to store: If you plan to use up your whole grain flour quickly, it will keep in airtight containers on a cool, dry pantry shelf for 1 to 3 months. We suggest tasting the flour as it ages because some varieties may age, which is to say become bitter, more quickly than others. If you plan to use your flour more gradually, then freezer storage is recommended to maintain freshness for 2 to 6 months.29 The refrigerator is a good option if freezer space is low. You can empty the whole flour bag into your storage container of choice or wrap the original flour bag in an airtight plastic bag.30