potato salad

Cheryl asked 4 years ago

How long can I leave potato salad with mayonnaise out at room temperature when I take it to a family get together or picnic?

1 Answers
Mark Staff answered 4 years ago

Thanks for the good question, Cheryl.
When a food is added to mayonnaise, such as potato, this raises the pH, which means there is less acid available to stop the growth of pathogenic bacteria. In this case, the potato salad should not be left at room temperature for more than 4 hours. If longer than that, throw it out!
An interesting fact – commercially prepared mayonnaise doesn’t need to be refrigerated for safety reasons because has a low pH, meaning there is a lot of acid (from added vinegar or lemon juice). However, when another food like tuna, potato, etc. is added to mayonnaise, this reduces the amount of acid and then the mayonnaise can support the growth of disease-causing (pathogenic) bacteria. 

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