Commercially produced mayonnaise differs significantly from homemade versions. Store-bought mayonnaise is made with pasteurized eggs, which eliminates many pathogens that can be present in raw eggs. It also often contains preservatives and stabilizers designed to extend shelf life and maintain quality. These factors make commercial mayonnaise far more stable and safer than homemade mayonnaise, particularly before opening.
Homemade mayonnaise, by contrast, typically uses raw egg yolks and no preservatives. While delicious, it is much more vulnerable to bacterial growth and spoilage, making careful storage essential.
Refrigeration: when it’s necessary
Store-bought mayonnaise:
Once opened, commercially prepared mayonnaise should always be stored in the refrigerator. While it may be shelf-stable before opening, exposure to air, utensils, and fluctuating temperatures increases the risk of contamination. Refrigeration slows bacterial growth and helps preserve flavor, texture, and safety.
Homemade mayonnaise:
Homemade mayonnaise should be refrigerated at all times and used within a very short window—usually 3 to 5 days. Because it lacks preservatives and often contains raw egg yolks, it can spoil quickly, even when kept cold.
During meals and gatherings:
Leaving mayonnaise out briefly during a meal—such as on a dinner table or picnic spread—is generally safe for a short period. However, it should not remain unrefrigerated for extended periods, especially in warm weather. As a general rule, mayonnaise should not sit out for more than one to two hours, and even less time if temperatures are high. Warm conditions dramatically accelerate bacterial growth.
Why proper storage matters
Mayonnaise has long been blamed for food poisoning, but it is often unfairly accused. In many cases, illness results not from mayonnaise itself but from cross-contamination. Examples include using the same knife or spoon for raw meat and then dipping it into the jar, double-dipping utensils, or returning mayonnaise that has been left out for too long back to the refrigerator.
Over time, improper storage can also cause mayonnaise to separate, develop off odors, or take on an unpleasant taste. While these changes don’t always mean it’s unsafe, they are strong indicators that the product’s quality has declined and it should be discarded.
Practical storage tips
Always refrigerate mayonnaise after opening
Keep homemade mayonnaise cold at all times
Avoid leaving mayonnaise out for long periods, especially in warm environments
Use clean utensils every time to prevent contamination
Discard mayonnaise if it smells sour, looks separated, or tastes off
The bottom line
Mayonnaise is safe and reliable when handled properly. Refrigeration after opening is essential, homemade versions require extra caution, and clean handling makes a significant difference in safety. By storing mayonnaise correctly and paying attention to temperature and hygiene, you can enjoy it confidently as part of everyday meals without unnecessary risk.
Understanding these basics helps ensure that this familiar condiment remains both delicious and safe—from the refrigerator to the table and back again.