Q: I’ve always been told that it is not the mayonnaise but the potatoes in potato salad that will make you sick on a hot day. Is this true?
A: The culprit isn’t the mayonnaise or the potatoes. The real risks are hands and heat, says Ben Chapman, an associate professor at N.C. State University.
If you have bacteria, such as staph, on your hands, you transfer it to salad ingredients when you cut them up. Since potatoes and hard-boiled eggs may be warm, bacteria can grow on them.
Commercial mayonnaise gives you a little protection, because it has acidity that keeps bacteria from growing so quickly. But that’s not enough to stop trouble when you leave potato salad out in the sun.
Make sure you wash your hands and don’t let potato salad sit out for more than an hour above 90 degrees.