It’s likely that you’re still using the same bag of all-purpose flour that you bought a while back, perhaps when you first settled into your current home. As you reach for that half-used, opened bag on your shelf, it’s natural to wonder: Does flour expire? How long can it sit in your pantry before it goes bad? If all-purpose flour is prone to spoilage, how can you tell when it’s time for a replacement? Let’s explore these questions.
### Is All-Purpose Flour Shelf Stable?
To begin with, yes, all-purpose flour is indeed shelf-stable. According to the US Department of Agriculture’s Food Safety and Inspection Service, “shelf-stable” means it doesn’t require refrigeration once opened. However, the FSIS also reminds us that eventually, all foods spoil if not preserved properly. This holds true for flour as well, as it can go bad over time.
### Flour Rarely Spoils, But When It Does, Here’s How
How exactly does all-purpose flour spoil? Interestingly, it’s not the starch in the flour that deteriorates but the wheat protein, known as gluten. Karin Allen, a food quality specialist, explains that when gluten-forming proteins are exposed to air, they undergo significant changes, limiting gluten formation. This results in a more crumbly texture in your baked goods, making it harder to achieve that stretchy, starchy quality found in fresh flour. Gwen Adams from King Arthur Flour notes that aged flour may cause bread to rise less and cakes to sink.
### How To Know If Flour Has Gone Bad
The most straightforward way to determine if your flour has passed its prime is by checking the best-by date. “The typical shelf life of all-purpose flour is about 1 year or longer from when it’s milled,” Adams says. If you don’t remember when you bought it or if you transferred it to another container, smelling is your next best bet. According to Sarah House at Bob’s Red Mill, old flour emits an off, musty odor that will affect the final product, while fresh flour has little fragrance and smells like clean grain.
The shelf life of all-purpose flour is longer than that of whole wheat or other whole grain flours because the germ, which contains oils that can go rancid, is removed during milling. If you’re not using whole wheat flour within a month, it’s best to store it in the fridge or freezer.
### How To Store Flour So It Stays Fresh
To extend flour’s life, proper storage is crucial. House advises keeping all-purpose flour in an airtight container in a cool, dry place, which can prolong its shelf-life up to 24 months. The freezer is also a great option for white flours, but ensure they return to room temperature before use. Generally, you don’t need to worry much about flour spoiling or ruining your bakes if stored correctly. Adams points out that all-purpose flour rarely develops rancid flavors, due to its low fat content. However, if you’re uncertain about how long flour’s been in your pantry, it might be wise to invest in a new bag.
