French fries are delicious, but notoriously unhealthy. A research team at the University of Illinois, however, has developed a deceptively straightforward method to keep the satisfying taste and crunch without requiring as much oil.

The cooking method combines traditional frying and microwave heating. Adding that microwave step could reduce the amount of oil used in the process, meaning you would absorb less fat with each bite. All the secrets to being able to cook fries in this way have been laid out in two studies published in Current Research in Food Science and The Journal of Food Science.

French Fries and Health

Although popular, fried foods contain high levels of fat, which is linked to several health problems, including obesity and hypertension. “Consumers want healthy foods, but at the time of purchase, cravings often prevail,” says Pawan Singh Takhar, author of one of the two studies. “The high oil content adds flavor, but it also contains a lot of energy and calories.”

It’s precisely with the goal of helping consumers make better food choices without feeling deprived that researchers have been trying to figure out how they can cook healthier french fries, achieving lower fat content without altering their taste and texture.

One of the main difficulties in frying, as the studies explain, is preventing the oil from penetrating the food. In the early stages of the french fry process, in fact, the pores of the potato are filled with water, leaving no room for the oil.

As cooking continues, however, the water evaporates, creating empty spaces that allow the oil to be drawn in by negative pressure. Much of the frying process takes place under that negative pressure, which essentially increases the tendency of the oil to be sucked into the fries

A New Wavelength

In the new study, therefore, the researchers tried to figure out how to extend the time in positive pressure and reduce the period under negative pressure. “When we heat something in a traditional oven, the heat transfers from the outside to the inside, but a microwave oven heats from the inside to the outside because the microwaves penetrate everywhere in the material,” Takhar says.

Specifically, microwaves cause water molecules to oscillate, resulting in increased vapor formation and thus shifting the pressure profile toward positive values that prevent the oil from being easily absorbed.

Microwave frying alone, however, would not produce the desired texture. “If only microwaving is used, the food turns out mushy,” says Takhar. In order to achieve crispness, frying and microwaving should be combined.

To achieve the right balance, the researchers carried out an experiment in which they specially designed a microwave fryer, monitoring temperature, pressure, volume, texture, moisture, and oil content of the chips. “We propose to combine the two methods in the same device. Traditional heating maintains crispness, while microwave heating reduces oil consumption,” the study concludes.