real mayo safety

When you are talking about real mayo I assume you are talking about commercial mayonnaise. If so refrigeration for commercial products is so the product will not turn rancid and break down. . Commercial mayo is high in acid and fat, so it is not a big safety concern like there is with homemade homemade mayo If you leave it out too long it will separate and turn oily and also gets rancid pretty quickly.

If you left it out for a few hours or even overnight you are probably ok. Look at it and see if it looks ok and smells ok. If you notice changes and an off odor then toss it.

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Nellie Oehler.