Potato salad is safe to leave out of the refrigerator for one to two hours max—but it’s not the mayonnaise that will make you sick.
Leaving potato salad out at room temperature may be one of the oldest potluck, picnic, BBQ, block party, and cookout concerns around. So how long can you leave mayo-based dishes at room temperature (or yard temperature) before they’ll go bad? And will they even actually make you sick?
A lot of us already know that, on its own, commercial mayonnaise poses no threat of food poisoning when kept at room temperature (although it may get a funky flavor you probably want to avoid). But when mayo, a perfectly good kid in his own right, starts hanging out with troublemakers (cross-contaminated or low-acid foods), the likelihood that he will toilet-paper your house (i.e., cause food poisoning) is pretty high. And even if you’re proud of your remodeled bathroom, you probably want to avoid sending friends and family to get a nice close look at it after they try your famous potato salad at the Fourth of July or Labor Day barbecue.
So how long are mayo-based salads safe to serve at room temperature? Between one to two hours, according to the folks at the FDA (same goes for other foods that require refrigeration). It takes roughly two hours for bacteria in foods to grow to dangerous levels, which is why you want to minimize the amount of time food is in the temperature danger zone (between 41 degrees and 135 degrees Fahrenheit). On days that are 90 degrees Fahrenheit or warmer, that time shrinks to one hour.
In general, it’s always best to keep food in the fridge (if you’re hosting at home) or in an ice-packed cooler until the moment you serve it, and then put it back immediately after lunch. If it sits out for longer than an hour, your best bet is to throw away the leftovers. And if the ice melts in the cooler? Yup, throw that food away too—cold water does not prevent mayo-based salads from becoming contaminated the way ice does. Down with food poisoning, up with safe and delicious barbecues!
For extra credit, make your own mayo too:
But if you’re still suspicious (or just hate mayonnaise), skip the white stuff altogether and make a mayo-free potato salad instead!