Then there is the potluck and picnic where food is made with mayonnaise. The food might sit out for hours in a non-refrigerated state. Since mayonnaise is made using raw eggs, food safety guidelines tell us that it should not sit out for more than a couple of hours. So, we tend to stick with the food safety guidelines.
Color Change. Discoloration is one of the first signs of spoiled mayonnaise. Noticeable change of color, like darker shade of white or a brownish-yellow color.
Visible Molds. Look for signs of mold. Any organic growths inside the neck of the jar, like mold or spores.
Texture Changes. The mayo should have a creamy consistency
Smell. Off, acidic, or putrid smell. Even though mayonnaise has vinegar, it should not smell overly sour or acidic.
Taste. If it tastes sour or just off, it is a red flag that it is spoiled.