In reality, Cacio e Pepe is notoriously difficult to get right, with the pecorino often forming into clumps, rather than a smooth, creamy sauce. Because of this, numerous restaurants now add ingredients like butter or cream to the sauce to help stabilise it. As you might imagine, there are some traditionalists for whom this situation is unacceptable :)
But a group of Italian physicists may have the solution for even the least-skilled of home chefs. In a new paper published in Physics of Fluids they report on their "scientifically optimized recipe" for Cacio e Pepe sauce that they say enables "a consistently flawless execution of this classic dish" - no additional ingredients or laboratory equipment needed.
They have achieved this by systematically analysing the so-called 'phase behaviour' of the sauce. In other words, they've methodically varied the proportions of cheese, water, and starch in the recipe, while controlling the cooking temperatures, to identify the combination of factors that produce the most stable, most creamy sauce. For each recipe variation, they carried out taste tests of the resulting Cacio e Pepe with their lab colleagues.
It turns out that the key factor is the ratio of starch to cheese. When starch concentrations were too low (below 1%, relative to the amount of cheese), the researchers found that unpleasant clumps formed in the sauce - a situation they call the “Mozzarella Phase". When there was too much starch (above 4%), the sauce became stiff and glue-like. The ideal range, they say, lies between 2% and 3%.
In a home kitchen, here are the ingredients you need to make their optimized recipe for two hungry people.
- 240 grams of pasta (tonnarelli, spaghetti or rigatoni)
- 160 grams of cheese
- As much freshly ground black pepper as you like.
Cook the pasta as normal in salted water until it is al dente, reserving a small amount of the cooking water before draining it.
Achieving the correct cheese-to-starch ratio requires 4 grams of starch, which is more than pasta cooking water typically contains. So, instead, while your pasta is cooking, make a separate starchy solution by dissolving 4 grams of powdered starch (e.g. corn starch) in 40 grams of water, heating it gently until it thickens and turns from cloudy to nearly clear. Let it cool for a few minutes.
Then, blend the starch solution with your grated cheese, adding a splash of the reserved cooking water if needed.
Once the pasta has been drained, let it cool down for up to a minute before adding it to the sauce. Mix them together, ensuring the pasta is evenly coated. Again, you can adjust the consistency by gradually adding small amounts of the reserved pasta water as needed. This will still keep you within the ideal starch range.
Buon appetito!
