Mayonnaise is a common household staple, used as a condiment and an ingredient in many different dishes. However, many people wonder whether it should always be stored in the refrigerator or if it is safe to leave it on the kitchen counter. Proper storage is important because it helps maintain its freshness, quality, and safety.

Mayonnaise is made from oil, egg yolks, and an acid such as vinegar or lemon juice. Commercial varieties often contain pasteurized eggs and preservatives, which help extend their shelf life. Homemade mayonnaise, on the other hand, is more vulnerable to spoilage. Although its acidity can slow bacterial growth, it does not completely prevent it.

According to food safety guidelines, opened mayonnaise should be refrigerated and should not remain at room temperature for more than two hours. In particularly hot conditions, this limit drops to one hour. Keeping mayonnaise below 40°F (4°C) helps slow bacterial growth and preserve its quality. Leaving it out for too long can increase the risk of harmful bacteria, including Salmonella and Listeria.

It is also important to recognize signs of spoilage. Mayonnaise that develops an unusual smell, changes color, separates, or shows visible mold should be discarded. Even if it looks normal, mayonnaise that has been left out beyond the recommended time should not be considered safe. Storing it properly in the refrigerator is the simplest way to protect its freshness and reduce the risk of foodborne illness.