Scientists have found a new way to cook french fries. It combines traditional frying with microwave heating, and the extra microwave step could help the fries take in less oil. The method is described in two studies published in Current Research in Food Science and the Journal of Food Science.
Fried foods are popular, but they are high in fat. "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 researchers wanted fries with less fat but the same taste and texture.
The hard part is stopping oil from getting in. At the start of frying, the tiny holes in a potato are filled with water, so there is no room for oil. As the water turns to steam, it creates positive pressure inside the potato, which helps keep the oil out.
Later, however, the water escapes and leaves empty spaces. The pressure inside turns negative, and oil gets pulled in. Much of the frying happens under this negative pressure.
In one of the studies, the researchers looked for a way to keep the positive pressure for longer. "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. Microwaves make water molecules vibrate, which produces more steam and keeps the pressure positive.
Microwaves alone are not enough, though. "If only microwaving is used, the food turns out mushy," says Takhar. To get crispy fries, frying is still needed.
So the researchers built a special microwave fryer and tested it, checking the temperature, pressure, moisture, texture, and oil content of the fries. "We propose to combine the two methods in the same device. Traditional heating maintains crispness, while microwave heating reduces oil consumption," the study concludes.