A group of German physicists at the Max Planck Institute have developed a fool-proof recipe for an infamously difficult pasta dish, Cacio e Pepe.

German physicists develop fool-proof Cacio e Pepe recipe

Across the world, many blasphemous acts are committed against pasta every day, seasoning with ketchup or snapping spaghetti in half pre-boil to name a few. But even the most well-intentioned cooks can fall foul, especially when it comes to the deceptively complicated Cacio e Pepe.

Spaghetti, pecorino cheese and pepper? What could possibly go wrong? Lots. Newcomers to Cacio e Pepe are often plagued with a hard, clumpy sauce which cannot be saved, meaning a waste of perfectly good cheese. Now, physicists at the Max Planck Institute in Munich have found the answer. 

“We started talking about the idea because at [Max Planck] we study phase separation. [...] This is the physical theory which explains how mixtures are stable with respect to temperature,” researcher Ivan Di Terlizzi told the BBC.

“In lots of physics books, you can find the phase diagram of water. This tells you that if the temperature is above 100 degrees celsius, then you have vapour, so the phase of water, is vapour,” Di Terlizzi explained, “If you go below 100 [degrees] you have the liquid phase and if you go below zero you have the solid phase. Of course, this can be generalised to other substances and we wanted to do a phase diagram for the sauce of Cacio e Pepe.” 

Starch - often in the form of leftover pasta water - is Cacio e Pepe’s hidden ingredient, and to stop your cheese from clumping you need a specific amount of starch. Di Terlizzi and colleagues created a phase diagram for starch and temperature. In the low-starch-concentration-and-high-temperature region of the diagram, they found the “mozzarella phase”, the right mixture for a perfect Cacio e Pepe.

How to stop Cacio e Pepe sauce from clumping

So how can you take advantage of this groundbreaking discovery? In a recipe for two, before you cook your spaghetti, dissolve 4 grammes of corn starch in 40 millilitres of hot water until forms a gel. 

Once your corn starch gel is cooled, mix it with your 160 grams of pecorino cheese and black pepper. Cook and drain 240 grams of spaghetti, but keep a little pasta water in the pot. Once it has cooled, combine your ingredients, stir and say “buon appetito”.

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