Does Flour expire?
Refined white flour is mostly starch and protein with the oily germ removed, so it lasts well in a sealed container. Wholemeal and stoneground flours keep the germ, and that small fraction of oil oxidises to give the sharp, bitter, crayon-like smell that is the reliable sign flour has turned. Freezing wholemeal flour stops the process almost completely and is worth doing if you buy it in bulk. The other failure is not chemical but biological: pantry moth larvae arrive in the bag from the shop and spread through a cupboard, and webbing in a bag means the whole cupboard needs emptying.
How to store it
- Airtight container, cool and dark — not the original paper bag.
- Freeze wholemeal and speciality flours.
- Freezing a new bag for 48 hours kills any moth eggs that came with it.
How to tell it has gone
- A sharp, bitter or crayon-like smell is rancid germ oil.
- Webbing, clumps or small moving larvae mean pantry moths.
"Use by" and "best before" are legally different. Use-by is a safety date and should be respected; best-before is about quality, and food is usually fine well past it. Where the two diverge matters, the page above says which applies.
Common questions
- Does Flour expire?
- White flour keeps 6-12 months; wholemeal goes rancid in 3-6 because the wheat germ oil oxidises.
- How long does Flour last?
- White: 6-12 months. Wholemeal: 3-6 months at room temperature
Related pages
- Does Eggs expire? Eggs stay usable for weeks past the date on the box, and the float test tells you about age rather than safety.
- Does Medicines expire? Most solid medicines keep much of their potency for years past the date — but a handful genuinely must not be used late.
- Does Petrol and diesel expire? Petrol goes stale within months, and ethanol blends go faster because they absorb water.
- Does Batteries expire? They self-discharge on the shelf, at very different rates by chemistry — and alkalines leak when flat.
- Does Wine expire? The great majority of wine is meant to be drunk within a year or two. Very little of it improves.
- Does Chocolate expire? It keeps far longer than the date. The white bloom on old chocolate is fat or sugar, not mould.
- Does Household bleach expire? It loses strength within months and eventually becomes salt water. This surprises most people.
- Does Paint expire? Unopened water-based paint keeps a few years; opened tins depend entirely on how well they were sealed.
- Does Honey expire? Does not expire
- Does Milk expire? Has a real expiry date
- Does Sunscreen expire? Unsafe or ineffective after the date
- Does Salt expire? Does not expire
- Does Frozen food expire? Indefinite if stored properly
- Does Canned food expire? Indefinite if stored properly
Sources
- Food Safety and Inspection Service — US Department of Agriculture (Public domain (US Government))