Does your cacio e pepe turn out lumpy? Try this 'scientifically optimized' pasta recipe

As It Happens5:55Physicists unveil 'scientifically optimized recipe' for cacio e pepe

Physicist Ivan Di Terlizzi wasn't having much luck making cacio e pepe in the kitchen, so he instead decided to perfect it in a lab. 

The classic Italian dish contains just four simple ingredients: pecorino romano cheese, black pepper, pasta and water. But if the ratios or temperatures are even slightly off, the sauce that should be creamy and rich can instead turn out curdled and lumpy.

"It's a pasta where the sauce is smooth and fills your mouth with the saltiness and the richness of the cheese and the heat of the pepper," Di Terlizzi, an Italian ex-pat living in Dresden, Germany, told As It Happens host Nil Kӧksal.

"It should be, like, homogeneously felt by the whole mouth, which is again the point of having a super smooth sauce — which is the aim of our study."

Di Terlizzi and several of his Italian colleagues at the Max Planck Institute for the Physics of Complex Systems tested hundreds of variations of cacio e pepe in order to present a "scientifically optimized" recipe that would create a "consistently flawless execution of this classic dish."

The study was published on arXiv, a site that hosts academic papers that have not yet been peer-reviewed. 

"I'm sure that chefs in Rome's historic trattorias will be relieved to hear that a group of scientists in Dresden have finally cracked the code to the perfect cacio e pepe," Mark Cirillo, founder of  the Cucinato Italian Culinary Studio in Toronto, told CBC in an email. 

"But seriously, if the 'scientifically optimized' method gives more people the confidence to make and enjoy cacio e pepe, we're all for it."

'There is a critical amount of starch'

Cacio e pepe appears, at first glance, deceptively simple. You boil pasta, usually spaghetti, return the starchy water to the pan, and then add cheese and pepper, heating and stirring until you achieve a perfect creamy blend.

But it's a finicky dish, Di Terlizzi says, and if not done properly, the proteins in the cheese will break down, causing it to curdle.

"So instead of having the smooth and rich sauce that you dream of, you basically get a mozzarella," Di Terlizzi said. "I'm not saying that mozzarella is bad — but it's bad when you're looking for a smooth cacio e pepe."

To figure out exactly when and why this occurs, he and his colleagues combined various amounts of cheese to water with a fixed level of starch at a constant temperature, extracted samples in petri dishes, took hundreds of photographs, then mapped the photos based on the sauce's consistency.

"What we discovered is that there is a critical amount of starch that you need for which the sauce is stable at all temperatures," Di Terlizzi said. 

Oftentimes, he says, pasta water doesn't retain enough starch to reach "this critical value." The workaround? Add cornstarch, about two grams per serving.

The team tested a cornstarch-enriched recipe by Italian chef Luciano Monosilio, and found it to be "foolproof."

Not for Nonnas

This tip won't come as a shock to anyone who has worked in an Italian restaurant, says Canadian Italian Chef Massimo Capra.

"You think that in restaurants, in busy restaurants in Italy, they make cacio e pepe to order without any help?" he told CBC.

Capra says his Ontario restaurants use cornstarch, as well as other "little tricks" like whipping up batches of starchy pasta water ahead of time.

But when cooking at home, he says he wouldn't recommend this shortcut. There's simply no need, he says, when old-fashioned trial-and-error will get you there.

"You might fail a couple of times, but at the end of it, you're going to end up learning," he said. "If you pay attention to what you're doing, you're going to end up with a great recipe."

Di Terlizzi agrees that with experience, people can learn "to do this in such a way that everything is emulsified to perfection."

But this recipe, he says, is not for pasta aficionados and Italian grandmothers who have been cooking it for decades. 

"It's much easier. It's something that you read on a piece of paper, and every person who can cook pasta, a normal pasta, can do this as well," he said.

"This is just more reproducible, which is all about science, right? Science must be reproducible."