Researching one's favorite dish is probably not on the to-do list of most physicists.

How do you mix cheese with hot water without it clumping? This is a crucial question for anyone who has ever attempted—more or less successfully—to prepare the popular Italian pasta recipe Cacio e Pepe, which consists of pasta, the Italian hard cheese Pecorino, and pepper.

Physics has now set out to solve this complicated kitchen puzzle and share it with pasta fans all over the world: In the journal "Physics of Fluids," scientists from the Max Planck Institute for the Physics of Complex Systems in Dresden, the University of Padua, and other institutions report on their findings—and, at least in their view, provide an "idiot-proof" recipe.

Fatty substances like cheese don't normally mix well with water, which is why starch is an important binding agent. Through tests, the research team found that 2 to 3 percent starch relative to the amount of cheese is optimal for a creamy, uniform sauce. At less than 1 percent, the risk of lumps is too high, and at more than 4 percent, the sauce becomes stiff and unappetizing.

Also important: the heat – because the sauce can't tolerate much of it. Excessively high temperatures destroy the proteins in the cheese and cause it to clump – a process the researchers call the undesirable "mozzarella phase." Therefore, the water should be cooler when mixing it with the cheese.

"A true Italian grandmother would never need a scientific recipe for cacio e pepe," the study states. "For everyone else, this guide offers a practical way to master the dish."

• The researchers advise anyone who wants to try this to first mix a starch solution—preferably potato starch or cornstarch—rather than relying on pasta water, whose starch content is unknown. For example, dissolve four grams of starch in 40 grams of water and heat until a gel-like consistency forms.
• Another 80 grams of water are added to this gel, also to cool the mass.
• Only then is the pecorino (in this example 160 grams) stirred into the starch solution until a homogeneous consistency is achieved.
• Then just heat the sauce to cooking temperature. Add pepper, add pasta, and you're done.

In addition to scientific curiosity, the researchers also had a selfish interest: "We are Italians living abroad. We often eat dinner together and cook traditional recipes," co-author Ivan Di Terlizzi of the Max Planck Institute in Dresden is quoted as saying in a press release from the American Institute of Physics. Cacio e Pepe seemed like an interesting dish from a physical perspective. And: "Of course, there was also the practical goal of not wasting the good Pecorino cheese."