Should Mayonnaise Be Refrigerated?
Mayonnaise is a common kitchen staple, but how it’s stored matters more than many people realize. Improper storage can increase the risk of foodborne illness and shorten its shelf life.
The Science Behind Mayonnaise
Mayonnaise is an emulsion made from oil, egg yolks, and an acid such as vinegar or lemon juice. The egg yolks contain lecithin, which binds the ingredients together.
Commercial mayonnaise is made with pasteurized eggs and often includes preservatives, giving it a longer shelf life. Homemade mayonnaise, on the other hand, lacks these protections and spoils much faster.
While the acidic ingredients slow bacterial growth, they don’t eliminate it entirely—especially once the jar is opened.
Why Temperature Matters
Bacteria multiply rapidly at room temperature. Refrigeration slows this process significantly, keeping mayonnaise safe and fresh for longer. For food safety, mayonnaise should be stored at 40°F (4°C) or below.
Storage Rules You Should Follow
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Unopened commercial mayonnaise: Can be stored in a cool pantry until opened (check the label).
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Opened commercial mayonnaise: Always refrigerate and use within the recommended time frame.
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Homemade mayonnaise: Must be refrigerated immediately and used within a few days.
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Left out for more than 2 hours (or 1 hour in hot conditions): Best to discard.
The Bottom Line
Once opened, mayonnaise belongs in the fridge. Refrigeration protects against bacterial growth and preserves quality. When in doubt, cold storage is the safest choice—for both taste and health.
