Flour Storage Basics

When you store all-purpose flour in an airtight container, the average shelf life is up to eight months. If you place that same container in the refrigerator, you can extend the shelf life to one year. Whole-wheat flour, on the other hand, has a much shorter shelf life. Because this flour still contains wheat germ, it contains oils. These oils, when exposed to oxygen, break down and cause the flour to become rancid. In a container, whole wheat flours typically last four to six weeks. If you grind your own flour, it is best to store the wheat berries and grind when needed.

Mylar Bags

Mylar bags provide a barrier from moisture, light and oxygen, keeping food fresh for longer periods. Made from multiple layers of poly film and aluminum foil laminated together, Mylar bags create a durable storage container. While blocking light, moisture and air, the thick material also helps protect against accidental puncture. Mylar bags come in 1-gallon bags or larger sizes to line buckets. Heat-sealing these bags allows for complete protection from the elements and extends the life of your flour. Flour stored in Mylar bags with oxygen absorbers can last as long as five years, while whole grains can last decades.

Oxygen Absorbers

The main component that shortens the life of flour when stored is oxygen. Oxygen absorbers work by absorbing the surrounding oxygen and binding it with finely ground iron. By removing the surrounding oxygen, the flour is unable to oxidize, thus stopping the flour from going rancid. Food grade oxygen absorbers go right into the Mylar bag with the flour to remove any remaining oxygen after the bag has been sealed.

Packing the Bags

When packing your flour into a 1-gallon Mylar bag, begin by labeling the bag. Because these bags block light, they also block you from seeing the contents inside. Using a spoon or measuring cup, fill the bag with your desired flour. Leave 2 to 3 inches of space at the top of the bag to allow for sealing. Add your oxygen absorber. Use a paper towel to wipe any flour from the inside top of the bag, to ensure a tight seal. Fold over the top inch of the bag and run a regular clothes iron or hair straitening iron over the top of the bag for a few seconds.