The Science-Backed Method for Achieving Perfectly Crispy Roasted Potatoes

As the chilly fall season rolls in, we start craving comforting foods that warm us up. And when it comes to comfort, potatoes are always at the top of the list. Whether mashed, baked, boiled, or roasted, there's something about buttery or well-seasoned potatoes that feels like a cozy hug from the inside.

But did you know there’s a little-known trick to getting your roasted potatoes extra crispy? The best part is, you probably already have the secret ingredient in your kitchen.

So, what’s the secret ingredient? It’s baking soda.

Why does baking soda make potatoes so crispy?

In his recipe for perfectly crispy roasted potatoes, Chef John adds baking soda to the water before boiling, raising the pH level of the potatoes. This method, borrowed from J. Kenji López-Alt and the Serious Eats team, works wonders.

Experts explain that increasing the pH level in the water helps break down the pectin—the natural 'glue' that holds vegetables together—while also roughing up the potatoes. According to López-Alt, this pectin breakdown creates a starchy slurry, giving the potatoes a larger, more uneven surface area. "It’s this rough, starchy texture that creates such a deep, crispy crust when roasted," Chef John notes.

For Chef John's method, bring 6 cups of water to a boil with 4 1/2 teaspoons of kosher salt and just under 1/2 teaspoon of baking soda.

Once the potatoes are boiled, Chef John coats them in a mixture of oil and spices—his go-to seasoning from his high school diner days. He ensures the potatoes are well-coated before placing them in a 450°F oven. In just 45 to 60 minutes, you’ll have perfectly crispy roasted potatoes!

More Tips for the Crispiest Roasted Potatoes

If you don't have baking soda on hand, Chef Nick Ocando, culinary director of Allelo, Juno & the Peacock, and Pluma Lounge in downtown St. Petersburg, Florida, has some great tips for making crispy roasted potatoes without it.

•  “Always make sure your potatoes are as dry as possible—‘free of all water’—by drying them with a paper towel before seasoning,” says Ocando. “Excess moisture makes them steam instead of roast.”
• He also says to not overcrowd your roasting pan, roast in single layers, and season right before you cook them, “because salt will pull moisture to the surface and cause your potatoes to steam instead of roast.”

And there you have it—the key to achieving the crispiest roasted potatoes you’ve ever made. Combine this technique with our secret for the ultimate roasted potatoes, and you just might create the best potatoes you’ve ever tasted.