Physicists find key to perfect pasta – but not how Mamma used to make it

The Guardian

29-04-2025

It may be only pasta, pecorino and black pepper, but cacio e pepe is not nearly as easy to make as some would imagine.
However, researchers have come up with a scientific recipe that avoids a lumpy sauce every single time – but it all gets a lot more complicated.
Cacio e pepe is made by cooking pasta and using the resulting starchy water to create a sauce with grated cheese and pepper.
Now researchers recommend that the perfect recipe for two involves dissolving 5g of powdered starch in 50g of water rather than using the reserved pasta water – as traditional recipes do. Then, heat the mixture gently until it thickens and turns clear.
Next, add 100g of water to cool the mixture, before blending it with 200g of cheese and adding toasted black pepper.
The resulting sauce should then be mixed with 300g of pasta that has been cooked in slightly salted water until it is al dente, drained and allowed to cool slightly.
This step helps prevent the excessive heat from destabilising the sauce. Finally, they say a little reserved starchy water can be used to adjust the consistency as needed.
'A true Italian grandmother or a skilled home chef from Rome would never need a scientific recipe for cacio e pepe, relying instead on instinct and years of experience,' the researchers write. 'For everyone else, this guide offers a practical way to master the dish.'
Dr Ivan Di Terlizzi, one of the co-authors of the research, said the team consumed about 6kg of cheese for the study, with 'most of it eaten with bread'.
'Although we are still not tired of this delicious dish, one of the authors had blood tests showing very high cholesterol levels,' he added. 'It's the price of science!'
'When heated, cheese proteins change their configuration and, therefore, aggregate,' said Dr Daniel Busiello, another co-author of the study from Max Planck Institute for the Physics of Complex Systems in Germany. Starch, he said, mitigates this effect by binding to the cheese proteins, reducing their direct interactions and hence their formation of clumps.
To explore the secret to a smooth and creamy sauce, researchers carried out a number of experiments using a fixed cheese-to-water ratio, but with varying concentrations of starch. The latter was controlled by dissolving known quantities of dry corn starch in the water.
The results revealed fewer clumps occurred at lower temperatures, regardless of starch concentration, with the team adding that the proteins did not start to clump below 65C. As temperatures increased, higher concentrations of starch were needed to avoid clumps forming and prevent the 'mozzarella phase' – where huge wads of cheese appear.
'At higher starch concentrations, temperature becomes less of a concern, as the sauce remains smooth even with less precise heat control,' said Busiello.
Busiello added pasta water alone contains too little starch to reliably prevent clumping, only producing a smooth sauce with careful temperature control.
'Our recommended scientific approach uses a starch to cheese ratio between 2% and 3% by weight, allowing home cooks to reliably create a smooth sauce without worrying too much about temperature,' he said.