Italian scientists reveal the 'perfect' recipe for Cacio e pepe pasta - and how to avoid the dreaded clumps

Daily Mail​

29-04-2025

It's the beloved Italian dish that tastes delicious but is frustratingly difficult to cook.
At first glance Cacio e pepe looks like a simple recipe containing only three ingredients – pasta, Pecorino Romano cheese and black pepper.
Professional pasta chefs and Italian grandmothers have the ability to turn out a smooth, creamy sauce time and time again.
But as anyone who has tried to make it will know, the cheese will often clump when added to hot pasta water, turning it into a stringy, sticky mess.
Now, Italian scientists reveal how to make the perfect Cacio e pepe – without any of the dreaded clumps.
'We are Italians living abroad,' said Dr Ivan Di Terlizzi, from the Max Planck Institute for the Physics of Complex Systems in Germany, said. 'We often have dinner together and enjoy traditional cooking.
'Among the dishes we have cooked was Cacio e pepe, and we thought this might be an interesting physical system to study and describe. And of course, there was the practical aim to avoid wasting good pecorino.'
So, will you give their recipe a try?
Most people attempting to create the dish will collect their drained pasta water before stirring in the cheese.
While fatty substances like cheese cannot mix with water, the starch from the pasta helps bridge that gap.
In tests, the researchers discovered that a 2-3 per cent starch-to-cheese ratio produced the smoothest, most uniform sauce.
And the best way to ensure this proportion is to make your own starchy water, rather than relying on drained water from pasta, they said.
They recommend using powdered starch like potato or corn starch, and weighing out a quantity that is 2-3 per cent of the amount of cheese being used.
'Because starch is such an important ingredient, and the amount of starch can sharply determine where you end up, what we suggest is to use an amount of starch which is precisely measured,' Dr Di Terlizzi said.
'And this can only be done if you have the right amount of powdered starch in proportion to the amount of cheese that you're using.'
Once the starch is added to the water, the authors' instructions say to blend it with the cheese for a uniform consistency, before adding the sauce back into the pan and slowly heating it up to serving temperature.
How to make the perfect Cacio e pepe
For two hungry people:
Ingredients
- 300g pasta (tonnarelli is preferred, though spaghetti or rigatoni also works well)
- 200g cheese (traditionalists would insist on using Pecorino Romano DOP)
- 5g powdered starch (potato starch or corn starch)
- 150g water
- Black pepper (toasted whole black peppercorns, which are then grounded, are best)
Step 1: Dissolve the powdered starch in 50g water, heating the mixture gently until it thickens and turns from cloudy to nearly clear.
Step 2: Add 100g cold water to this mixture to cool it down.
Step 3: Using a blender, add the cheese to the starchy sauce.
Step 4: Add a generous amount of black pepper to the mixture.
Step 5: Meanwhile, cook the pasta in slightly salted water until it is al dente and leave to cool for a minute. Save some of the pasta cooking water before draining.
Step 6: Add the sauce back into the pan, stir in the pasta and heat it up very slowly to serving temperature.
Step 7: You can adjust the consistency by gradually adding the saved pasta water as needed.
Step 8: Garnish with grated cheese and pepper before serving.
This brings the researchers to another key element of the perfect Cacio e pepe sauce – heat, or rather, a lack of it.
They warned too much heat denatures the proteins inside the cheese, causing it to stick together and leading to the dreaded clumps.
Instead, the authors advise letting the starchy water cool before mixing in the cheese and bringing the sauce up to temperature as slowly as possible. Then, the final steps are to mix in the pepper and pasta, and eat.
Writing in the journal Physics of Fluids the team said: '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.
'For everyone else, this guide offers a practical way to master the dish.
'Preparing Cacio e pepe successfully depends on getting the balance just right, particularly the ratio of starch to cheese.
'The concentration of starch plays a crucial role in keeping the sauce creamy and smooth, without clumps or separation.'
They said their method is 'particularly useful for cooking large batches of pasta, where heat control can be challenging and requires extra care'.
The team also included researchers from the University of Barcelona, the University of Padova and the Institute of Science and Technology in Austria.
For future work they plan to look at other recipes including pasta alla gricia, which is Cacio e pepe plus cured pork cheek.
'This recipe seems to be easier to perform, and we don't know exactly why,' co-author Daniel Maria Busiello said.
'This is one idea we might explore in the future.'
HOW CAN YOU MAKE SPAGHETTI SNAP IN TWO?
Spaghetti's unusual shattering process has stumped science's best brains for years, including Nobel Prize winning physicist Richard Feynman.
However, researchers from MIT have finally shown how and why it can be done.
Two MIT students, Ronald Heisser and Vishal Patil, built a mechanical fracture device to uncontrollably twist and bend sticks of spaghetti.
Two clamps on either end of the device held a stick of spaghetti in place.
A clamp at one end could be rotated to twist the dry noodle by various degrees, while the other clamp slid toward the twisting clamp to bring the two ends of the spaghetti together, bending the stick.
They used the device to bend and twist hundreds of spaghetti sticks and recorded the entire fragmentation process with a camera, at up to a million frames per second.
They found that by first twisting the spaghetti at almost 360 degrees, then slowly bringing the two clamps together to bend it, the stick snapped exactly in two.
They found that if a 10-inch-long spaghetti stick is first twisted by about 270 degrees and then bent it will snap in two.
The snap-back, in which the stick will spring back in the opposite direction from which it was bent, is weakened in the presence of twist.
And, the twist-back, where the stick will essentially unwind to its original straightened configuration, releases energy from the rod, preventing additional fractures.