Physics

There’s science to making great fried rice

Chefs make the dish often without realizing the physics behind it

Science underlies what chefs in Chinese restaurants do to cook rice quickly and completely — without burning.

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March 4, 2020 at 6:45 am

To make fried rice like a pro, use science. That’s what two physicists now advise.

Chefs typically toss the frying food into the air from deep, rounded pans ⎯ or woks ⎯ before catching it again. Launching rice and its fixings allows a chef to cook it over really hot flames without burning. At times, temperatures in a pan can reach 1,200° Celsius (2,192° Fahrenheit). This helps create the tastiest stir-fried fare. Now, Hungtang Ko and David L. Hu have analyzed videos of five chefs cooking up fried rice in Chinese restaurants. By doing this, Ko and Hu uncovered the repeated motions used to toss that rice. Both Ko and Hu work at the Georgia Institute of Technology in Atlanta.

The scientists found that the chefs relied on a specific pattern of motion. And they repeated those motions about three times a second. Ko and Hu described those movements February 12 in the Journal of the Royal Society Interface. Each repetition included sliding a wok back and forth at the same time it was rocked to and fro. The chefs used the rim of the stovetop as a fulcrum on which to balance their pan as they rocked it.

Cooking fried rice like a pro requires tossing it in the air to avoid burning. Physicists analyzed details of chefs’ movements. They now report that sliding and rocking motions repeat about three times a second, launching the food from a wok. Blue lines track the edges of the pan, with the left side moving clockwise and the right side counterclockwise. The red line notes the motion of the wok’s center.

Cooks use similarly complex patterns of movement to cook up other foods. They will tilt and rotate batter in a pan, for instance, to get smooth, flat crepes.

Ko and Hu used a computer to simulate the trajectories of rice that would occur in a wok moved in various ways. Along the way, the scientists hit on some key culinary tips. The rocking and sliding motions shouldn’t be totally in sync. If they are, the rice won’t mix well and could burn. Also, the wok’s movements should repeat rapidly. Moving the wok even faster could launch the rice higher. That might allow cooking at higher temperatures, they say, and perhaps a quicker meal.

But faster shaking may be hard on a cook. Chefs at Chinese restaurants can struggle with shoulder pain, studies have shown. Rapidly shaking their heavy woks could be part of the problem. One solution, Ho and Ku suggest, might be a stir-frying robot. It could be built based on their newfound results, they say, to take the weight off chefs’ shoulders.