Does Mayonnaise Expire?
Yes, mayonnaise can expire. Unopened mayonnaise lasts 3-4 months past the printed date. Once opened, it should be used within 2-3 months when refrigerated. Unlike popular belief, commercial mayo is quite stable due to acidic ingredients, but it will eventually spoil.
Key Takeaways
- Commercial mayonnaise is more shelf-stable than homemade because it contains [vinegar](/does-vinegar-expire) or lemon juice that lowers pH and prevents bacterial growth.
- Homemade mayonnaise with raw eggs has a much shorter shelf life (about 1 week refrigerated).
- Mayonnaise left out at picnics is often blamed for foodborne illness, but usually the other ingredients (chicken, potatoes) are the culprits.
Explanation
Commercial mayonnaise is more shelf-stable than homemade because it contains vinegar or lemon juice that lowers pH and prevents bacterial growth. The eggs in commercial mayo are also pasteurized. Unopened jars are remarkably stable.
After opening, mayonnaise should always be refrigerated. It can actually last quite a while in the fridge because of its acidic nature. The two-month guideline is conservative; properly stored mayo often stays good longer.
Signs of spoiled mayonnaise include off or sour odors, yellowing or darkening color, separation that does not remix when stirred, and any visible mold. When in doubt, discard it - the risk is not worth saving a few dollars.
Things to Know
- Homemade mayonnaise with raw eggs has a much shorter shelf life (about 1 week refrigerated).
- Mayonnaise left out at picnics is often blamed for foodborne illness, but usually the other ingredients (chicken, potatoes) are the culprits.
- Reduced-fat mayonnaise may have shorter shelf life than full-fat versions.