French fries are loved for their crunchy bite and rich taste. But they soak up a lot of oil while frying, which adds extra fat and calories. Eating too much oily food can lead to weight gain and high blood pressure.
Researchers at the University of Illinois Urbana‑Champaign wondered if microwaves could help make fries that take up less oil but still stay crispy. Their experiments show that mixing microwave heating with normal frying can shorten cooking time, lower oil absorption, and keep the texture people expect.
Healthier Fries Without Losing Flavor
"People want food that is good for them, but cravings often win at the store. Oil gives flavor, but it also adds a lot of calories," explains Professor Pawan Singh Takhar, who leads the study. "Our goal is to cut the fat in fried foods while keeping taste and texture almost the same."
Takhar and doctoral student Yash Shah published two papers that describe what happens inside a fry when microwaves are used.
What a Special Microwave Fryer Does
The team worked with scientists at Washington State University who built a fryer that can run at two microwave frequencies: 2.45 GHz (the same as a kitchen microwave) and 5.8 GHz. Different frequencies move energy through food in different ways, changing how fast water molecules heat up.
Following the Fry’s Journey
Potatoes were peeled, cut into strips, blanched briefly, salted, and then fried in hot soybean oil at 180 °C. Throughout cooking, the researchers recorded temperature, pressure inside the pieces, size, texture, moisture, and how much oil was absorbed.
At the start, the tiny pores inside a potato are filled with water, leaving little room for oil. As the fry heats, water turns into steam and leaves the pores, creating a vacuum that pulls oil inside.
"Imagine a straw," Takhar says. "If you blow into it, liquid is pushed out (positive pressure). If you suck, liquid is drawn in (negative pressure). Food has millions of tiny straws. When the pressure becomes negative, oil rushes in."
Why Pressure Matters
The study found that up to 90 % of oil uptake happens while the fry is under negative pressure. Keeping the pressure positive for longer could stop oil from being sucked in.
Microwaves heat water all over the piece, not just from the outside. The extra steam raises internal pressure, making it harder for oil to enter.
Microwaves Speed Up Cooking
Computer models were used to test different scenarios. Compared with regular frying, microwave‑assisted frying removed moisture faster, cut total cooking time, and reduced oil uptake.
However, fries cooked only with microwaves stayed soft and did not become crispy.
Combining Two Techniques
Takhar suggests a hybrid fryer: first use conventional heat to brown and crisp the surface, then add microwave energy to drive out moisture quickly and keep oil out.
This approach could let manufacturers produce fries that are less oily but still crunchy, while also cooking faster—a win for health and efficiency.
Existing continuous fryers in large factories could be upgraded with inexpensive microwave generators, making the idea practical for commercial use.
The findings were published in the Journal of Food Science and Current Research in Food Science, with funding from the USDA National Institute of Food and Agriculture.