Leftover French fries can be delicious, but only if you reheat them correctly. If you’ve ever tried nuking your leftover fries hoping to recreate that crunchy goodness only to end up with a soggy mess, then you’ve already experienced first-hand why they’re on our list of foods you should never reheat in the microwave. But why exactly is that the case? Here’s what science has to say about it.
It all comes down to the way that microwaves operate. Contrary to forms of cooking that apply external heat which then moves to the inward through the food, microwaves work by causing the water in food to vibrate so much that it generates heat. That water turns to steam. Because the surrounding air in the appliance doesn’t get as hot, the water condenses on the food and prevents it from crisping up. In the case of French fries, this results in sogginess. Potatoes themselves contribute to the problem. They not only contain water but also absorb ambient moisture that starts to soften their crispy exterior.
What to use to reheat your fries instead of a microwave
You’ll get better results when reheating your French fries with just about any method besides the microwave. Probably the best approach is to use a deep fryer or Dutch oven, though with the downside that it’s a big production that requires a lot of oil and extensive clean-up, especially dealing with the used oil. If you happen to have an air fryer, it will use far less oil and is just about as easy as a microwave. If you don’t have an air fryer, you can always use an oven, or even a pan or skillet for an easy stovetop method.
If you absolutely have to use a microwave, at least coat your fries in a little bit of oil and wrap them with paper towels to absorb the moisture. Better yet, use a crisping tray. No matter what method you choose, just be sure to season your fries with a bit more salt before enjoying them again.
