Why French Fries Are The Worst Leftover Food

There's no doubt that hot and crispy french fries are one of the most beloved foods in the U.S. In fact, Americans consume 4.5 billion pounds per year, and there's even a designated day for the fried potato — July 13^th. As wonderful as french fries taste, the leftovers are a bland and soggy mess with a gritty texture. How can something so crispy and delicious turn into the flavor of cardboard just because it got cold? The answer lies in one word: chemistry.

French fries are primarily made of starch, which comes in the form of tiny crystals inside the potatoes. As the fries heat up, the crystals hydrate and make the french fry fluffy. As they cool, the texture changes, because the water leaves the crystals and enters the crust of the french fry, which is why they become soggy and flavorless. Heat helps enhance the flavor of food, which is another reason cold french fries are so undesirable. Leftover fries also lose their smell, which is one of the main reasons they taste so good to begin with.

If you find yourself with leftover french fries, not all hope is lost. They can be brought back to their golden splendor with just a little bit of cooking oil, an air fryer, or even a waffle iron. Using a microwave is the worst way to reheat french fries, because the moisture gets pulled out and trapped in the microwave then finds its way back to the fries. The trick is to rehydrate the fries at high temperatures and, if you're not using an air fryer, cooking oil. The cooking oil adds moisture and produces crispy skin, because it seals the outside of the french fry and locks in the moisture, rejuvenating the fries. 

Air fryers are great for cooking or reheating french fries because their design allows hot air to envelop food, like oil does in a deep fryer, and this produces similar results. However, for the best results, reheat french fries on the stovetop with just enough oil to cover the fries. The oil rehydrates the starch and adds crispness, similar to when the fries were originally cooked. It might take a little bit of time, but it's worth it. Just make sure not to throw out those leftover french fries.