For as much as 90% of the time a French fry spends in the deep fryer, the physics inside it amounts to a vacuum pulling oil into the potato. Researchers at the University of Illinois Urbana-Champaign think microwaves can flip that pressure, and their lab data suggest it works.
The team, led by food engineering professor Pawan Singh Takhar with doctoral student Yash Shah, reported results in two papers: one in the Journal of Food Science and a companion modeling study in Current Research in Food Science. The work was funded by the USDA National Institute of Food and Agriculture.
Their conclusion is not that anyone should microwave their fries. It is that a hybrid fryer, combining conventional oil heat with microwave energy in a single unit, could cut fat content without wrecking texture.
The Tiny Straws Inside Every Potato
At the start of frying, the potato's pores are full of water, and there is nowhere for oil to go. As frying continues, that water evaporates, opening pore space, and oil is drawn in by negative pressure.
Takhar explains it with a straw. Blow into a straw and liquid gets pushed out. Suck on it and liquid climbs. "Now imagine food materials have lots of tiny straws," he said in the university's announcement. Positive pressure keeps oil out. Negative pressure invites it in.
Because suction runs for up to 90% of the process, the engineering goal becomes obvious once stated: keep internal pressure positive longer and shorten the stretch when it is negative.
Two Frequencies, One Soggy Problem
For the experimental paper, the Illinois group worked with Washington State University colleagues who had built a specialized microwave fryer capable of running at 2.45 gigahertz, the frequency of a household microwave oven, and at 5.8 gigahertz.
Potatoes were rinsed, peeled, cut into strips, blanched, salted and fried in soybean oil preheated to 180 degrees Celsius. The researchers tracked temperature, internal pressure, volume, texture, moisture and oil content during and after cooking.
Microwaves heat differently. Rather than moving inward from the surface, they penetrate the strip and agitate water molecules throughout, generating vapor faster and shifting internal pressure toward the positive side. Across the experiments and the modeling work, microwave frying produced faster moisture loss, shorter cooking time, and lower oil intake than conventional frying when both were taken to the same final moisture content.
Then the obvious problem. Microwave energy on its own leaves fries soft rather than crisp. Crispness requires conventional heating, which is why the team proposes combining both methods in the same unit, using oil heat for browning and crunch while microwaves suppress oil uptake.
The second paper used mathematical modeling to explore variables that are difficult to measure directly, comparing 2.45 GHz, 5.8 GHz and conventional conditions across pressure, texture and oil absorption.
Takhar has also reported that microwaves applied during the cooling step after frying can pull oil content down further, which points to a second place a hybrid unit could intervene. "Conventional heating maintains the crispiness, while microwave heating lowers the oil intake," he said.
Why Fat in Fries Specifically Draws Attention
The interest in the frying step is not incidental. A study published in The BMJ in August 2025 gave fries their own unflattering headline. Drawing on more than 205,000 U.S. nurses and health professionals followed across three cohorts, researchers led by the Harvard T.H. Chan School of Public Health found that every three weekly servings of French fries were associated with a 20% higher rate of type 2 diabetes, while baked, boiled, and mashed potatoes showed no significant association.
Across nearly four decades of follow-up, 22,299 participants developed the disease. Replacing three weekly servings of fries with whole grains was estimated to lower the rate by 19%.
Potatoes overall were not blameless. Every three weekly servings of total potatoes was associated with a 5% higher rate, and swapping potatoes for white rice was associated with a higher risk rather than a lower one.
That was an observational study. It cannot establish that fries cause diabetes, and the researchers adjusted for lifestyle and dietary factors but could not eliminate all of them. Still, the preparation method, not the potato, carried most of the signal. Oil is the most obvious difference.
This Is a Factory Idea, Not a Kitchen Hack
Nobody is selling a hybrid microwave fryer. The researchers describe their work as fundamental mechanism research using experiments and physics-based modeling, with hybrid fryer design as a downstream application for industry and restaurants.
They do note a practical path: continuous fryers in large processing plants could be retrofitted with microwave generators, which are widely available and relatively inexpensive.
Two caveats deserve stating plainly. These studies measured oil uptake, moisture, pressure and texture. They did not measure acrylamide, the compound formed when starchy foods are cooked at high temperatures, so this line of work says nothing about that particular concern. And lower fat is not the same as healthy. A fry with less oil is still a fried potato.
Key Questions Answered
What did the researchers actually demonstrate?
That microwave energy during frying speeds moisture loss, shortens cooking time, and reduces oil absorption compared with conventional frying at the same final moisture content.
Why does oil get into fries in the first place?
As water evaporates, it leaves empty pores, and the resulting negative pressure draws oil in. This suction is active for as much as 90% of the frying process.
Can I do this at home?
No. The experiments used a specialized microwave fryer, and the proposed hybrid system does not exist as a consumer appliance.
Would the fries taste different?
Microwave energy alone produces soft, soggy fries. The proposal keeps conventional heating specifically to preserve browning and crunch.
Does this make French fries a healthy food?
It does not. Reducing oil content lowers calories and fat, but the research does not address acrylamide, salt or overall dietary pattern.
Why are fries singled out among potato dishes?
A large BMJ cohort analysis linked fries, but not baked, boiled or mashed potatoes, to higher type 2 diabetes rates, pointing to the frying step rather than the potato itself.
