My love for junk food is no secret in the test kitchen. In fact, I am the keeper of the Cook’s Illustrated team snack corner, which typically includes everything from chocolate bars and pretzels to popcorn and chips.
So I was excited when I was tasked with developing a recipe for kettle chips, the thick and crunchy style of potato chips that I happen to love. The prep work is a cinch—you don’t even have to peel the potatoes—and the frying method is actually tailor-made for home cooks (keep reading and I’ll explain why). Plus, if you’ve ever had freshly fried, still-warm chips, you know that they’re a real treat (especially homemade versions of classic flavors such as barbecue, sour cream and onion, and salt and vinegar). There’s also a certain satisfaction that comes from producing snack food that could pass for store-bought.
Before I dive into the distinctive feature of kettle chips—deep, satisfying crunch—it helps to know the basic differences between this style of chip and the thin and crispy kind (think Lay’s Classic). Crispy chips are cut thin and cooked relatively hot and fast, while kettle chips are cut roughly 50 percent thicker and fried at a lower temperature for longer.
Potato slice thickness impacts a chip’s texture, but it’s the frying time and temperature that make the most profound difference. In fact, when I dug through a stack of research papers to see how the two styles of chips are made commercially, it became clear that manufacturers have these details down to a science.
First, let’s look at the kettle kind. They’re batch‑fried in vats of oil, the temperature of which follows a U-curve that is key to creating their characteristic crunch. The process goes like this: The potato slices are dropped into moderately hot (about 300-degree) oil, which plunges to about 250 degrees. As the oil slowly heats back up, the starches inside the potatoes absorb water, forming a sticky gel that glues the potato cell walls together, like mortar strengthening a rock wall. Finally, the water is driven off, leaving behind a rigid net of crisscrossed starch molecules with an open, crunchy structure. (All the while, the chips are stirred, which prevents sticking.)
Meanwhile, crispy chips are made by propelling the potato slices quickly and continuously through hot (about 350-degree) oil along a conveyor belt—a process called continuous frying—which ensures that the oil temperature holds steady at a high enough temperature for the starches to desiccate before they can absorb water and create much sticky gel. As a result, the chips are delicate and crisp.
Generally speaking, it’s easy to follow a U-curve when frying at home because that drop in temperature happens naturally when you add cold food to hot oil, and it takes time to bring the oil back up to its starting temperature. But after making a few batches of kettle chips, I realized that you have to control how steeply the temperature drops and how quickly it recovers and that frying in a regular pot on a regular stove—as opposed to using a commercial setup—has its limitations.
When making chips at home, there is only one variety of potato to choose: russet. Good chips come from high‑starch, low‑sugar potatoes. Commercial producers actually use special varieties that are extremely low in sugar to prevent overbrowning; common russets (more accurately known as Russet Burbanks) are the closest available alternative.
I sliced a pound of russets into ¹⁄₁₆-inch-thick rounds using a mandoline and then heated 2 quarts of oil in a 7-quart Dutch oven to 300 degrees, mimicking the commercial method. But when I added all the potatoes, the limitations of my ordinary pot became obvious. The slices, which were covered in sticky surface starches, were crowded in the pot, and they stuck together even with constant stirring. So I took a cue from my recipe for Patatas Bravas (May/June 2016) and heated the oil for my next batch to 375 degrees, knowing that the higher temperature would help immediately dry out the potatoes’ surface starches and mitigate sticking (I’d still stir them as they fried).
Now the question was how much to turn down the heat, since that would determine how quickly the oil recovered to the 300-degree range and how much time the starches in the chips had to give up their water. I added the potatoes and played it safe by turning the stove dial to low—but I shouldn’t have. In total, that batch took more than 20 minutes to fry, and the chips were unpleasantly hard. That’s because with the longer cooking time, the water exited the gel so slowly that the starches had more time to organize into a denser, tougher structure.
Cranking the heat to high after adding the potatoes was also a mistake. First and foremost, the chips overbrowned. Second, a weaker gel formed and left behind a disorderly and brittle matrix of starch; as a result, the chips were more crispy than crunchy. Frying over medium heat was the answer: It allowed the oil to hover in that 250-degree “gel zone” for about 5 minutes so that the chips began to stiffen. After another 6 to 8 minutes—just 13 minutes total frying time—the oil temperature had rebounded to around 300 degrees, the rest of the water in the chips had evaporated, and they’d turned completely rigid and golden.
Now for those aforementioned seasonings. A smoky spice mix for barbecue chips was easy to make with pantry staples, and I imitated the other two classic flavors—sour cream and onion and salt and vinegar—with buttermilk powder and vinegar powder, respectively. Processing the seasonings in a spice grinder produced a fine powder that clung nicely when tossed with the hot chips.
If you’re on the fence about DIY snack food, take it from this aficionado: You’ll be wowed by these chips, and making them is easier than you’d think.