Ask Dr. Universe – French Fries

Dr. Universe: Why are French fries so good? – Emma, 8, Alaska

Dear Emma,

A good French fry starts with the right potato. My friend Rick Knowles is a potato researcher at Washington State University and told me all about the spuds.

It turns out there are certain kinds of potatoes that make the best fries. Two of them are the Clearwater Russet and Blazer Russet potatoes. These potatoes have a good texture and their long shape makes them great for cutting into fries.

If you took a bite of a raw potato, it probably wouldn’t taste very good. But when we cook a potato at just the right temperature, something called the Maillard reaction happens.

The Maillard reaction is a reaction in potatoes that happens between glucose, a kind of sugar, and amino acids, the building blocks of protein. Knowles explained that the Maillard reaction changes the flavors and odors of some foods that we cook.

“In the case of potatoes, we want a certain amount of Maillard reaction to give us the golden brown color and characteristic cooked flavor of the chips and fries, but not too much Maillard reaction,” Knowles said. “Otherwise we get dark colored fries that have a bitter, burnt flavor.”

You may have noticed the Maillard reaction doesn’t happen when we cook up mashed potatoes. That’s because we only boil the potatoes to around 212 degrees Fahrenheit. The Maillard reaction happens when foods like potatoes have just the right amount of glucose and amino acids and are heated to above 302 degrees Fahrenheit.

A big part of the flavor in fries also comes from the oil we use to fry them. A little salt also adds to the taste.

A lot of people in the food industry are very curious about flavor. In the lab here at WSU, Knowles and his team invite people to taste test French fries each year.

“We make them up right here,” Knowles said, when I visited him in the research building where he works.

Researchers in the Knowles lab study new potato varieties that they are growing in Oregon, Washington, and Idaho. They developed potatoes like the Clearwater Russet and Blazer Russet through a process called plant breeding. Plant breeding helps the researchers select the traits they want in a plant, like a certain shape, size, or a high amount of protein.

The team is helping farmers learn which potatoes people will buy and want to eat. In Washington state, we grow more than 9 billion pounds of potatoes every year and most of them will go on to become French fries.

You can also whip up some fries right at home with the help of a grown-up. My friends at WSU Extension even have a recipe for you to try: crispy potato wedges. Try out the science of cooking in your kitchen sometime, check out that Maillard reaction, and let us know how your potatoes turn out at

Dr. Universe