Phase behavior of Cacio and Pepe sauce

[mapt]

The secret is that restaurants which make traditional cacio e pepe are using pasta water to emulsify the sauce.

But it's not the same pasta water you're using at home!

Only a tiny amount of starch is coming off of the 500g of pasta you just cooked in the proper ratio in 5000g of water (with 50g of salt). They've been cooking with their pasta water all day or all week; It's completely full of starch that came off the other pasta.

Dump a bunch of cornstarch or flour in there to get above 1% concentration (or more efficiently, into a tiny portion in a bowl) to replicate the emulsifying effect, or just use a different emulsifier.

[csantini]

The trick is to:

   1. Cook the pasta in very little water ("pasta risottata").

   2. Vigorously agitate (emulsify) the sauce with that super starchy broth

If you do it right, no water is drained at all: https://www.youtube.com/watch?v=ZN8g_ZNAJcg

[wlll]

I make fresh tomato pasta sauces this way as well as the cheese based ones sometimes. A bit of butter and olive oil in the sauce, minimal water in with the pasta (I really like orecchiette) and finish the pasta off in the sauce with a bit of the minimal remaining water. Very clingy, very silky.

[chongli]

That video amuses me to no end! All that work to carefully make a delicious pasta and then such a tiny serving at the end!

The simple, classic Italian cheese pastas (cacio e pepe as well as carbonara) are so delicious you can't just eat a small bite. You need a big bowl!

[tommiegannert]

The phase diagrams are great. This really raises the bar for cook books. If you can't show a diagram to explain why you chose that ratio of ingredients, why should I trust you to have made the optimal sauce?

[gorgoiler]

I took a trip to my local university library once and found the food science section. It made On Food and Cooking look like Green Eggs and Ham in comparison and I learned more than I cared to about pineapple canning.

(To be fair, McGee’s work does exactly what I did but with multiple orders of magnitude more effort: summarizing food science journal papers into single paragraphs.)

One thing that’s always struck me as fun about cooking as a science is that your reagents need to be live calibrated by look and feel. Want to use the right amount of cyder vinegar but it’s from a brand / manufacturer you don’t know? You’re going to have to live titrate it with your mouth!

Don’t even get me started on inconsistencies between egg manufacturers. Clara’s lecithin content seems to be at least 10% stronger than Number 4’s, and she is also more tolerant of being stroked.

[joshvm]

This is ubiquitous in baking at least. Also in confectionery where phase changes and structures are important (the canonical example being tempering). The extreme is probably Modernist cuisine.

You can look at the book "ratio" which presents a small number of standard recipes as proportions, with some hints for modification. I'd also recommend Lateral Cooking which describes recipes in terms of spectrums of ingredient variation or addition, usually starting with the simplest form. Finally there's a lot of interest in physics for coffee brewing, particularly pourover, but I'm somewhat skeptical of the rigour in that field and how much of it translates to better tasting cups.

[gghootch]

Your comment is probably tongue in cheek, but this level of detail is pretty standard for advanced cooking. Serious Eats, Chef Steps or What’s Eating Dan have published loads of recipes backed up by research and accompanied by great graphs.

[djtango]

Science and empiricism usually eventually wins out over the long term but thankfully for human civilisation, people have been able to achieve extremely good outcomes in things with very loose models and folk wisdom - for instance sports people don't need to understand physics to "Bend it like Beckham"

In cooking, the folklore knew that salting your egg mix before beating an omelette long before Chemistry could catch up and explain it. In the meantime all the cynics were making worse omelettes

[s0rce]

I'm not sure most cookbooks claim to offer an optimal recipe or even that there is an optimal one and that preference may play a big role. Some sites like serious eats do more investigation but I agree, I really like the phase diagram approach. Seems to best apply for stabilized colloids (mayo, ice cream, vinaigrettes, etc).

[fvdessen]

As the paper says:

A true Italian grandmother or a skilled home chef from Rome would never need a scientific recipe for Cacio and pepe, relying instead on instinct and years of experience.

[cantSpellSober]

The Recipe section is mostly to show the problem is solved

> small temperature variations can completely compromise the recipe’s outcome

[joeross]

lol “optimal sauce” is such an HN approach to describing good food

[dbfclark]

Another completely viable solution (other than adding extra starch) I’ve found is to sprinkle a bit of sodium citrate (the sodium salt of citric acid, a common food additive and cheap on Amazon) over the cheese before adding to the pan. This improves the melting qualities of the cheese and avoids the starch issue altogether. You’re basically using pecorino velveeta.

[mgaunard]

One interesting aspect of pasta sauces is that the amount of starch they need is usually incompatible with the recommended amount of water to boil the pasta in, and if you use less water, your italian friends are going to complain.

Cheating by adding some starch is the right approach, and works much more reliably.

[Hikikomori]

Why do we need so much water when cooking pasta, is it even correct? I know pasta tend to stick if you have less water, boiling hard with lots of water alleviates that, but so does some stirring.

[gavindean90]

Use a short wide pan and just barely keep the noodles covered. You will get better pasta, easier cacio e Pepe and reduced energy costs related to pasta.

[toolslive]

Note that if you're after the perfect recipe and you want to find the ideal ratios/temperature aso, changing the setup "one factor at a time" is a working but sub-optimal strategy. You want to look into DoE (Design of Experiments)

[Metacelsus]

time to do a fractional factorial Cacio e Pepe!

[Keysh]

I like how the arXiv sub-category this paper is in is "Soft Condensed Matter".

Because of course it is.

(Also, the Acknowledgments ends with "We further thank [list of names] for their support and for eating up the sample leftovers.")

[gfna]

I would also like to see a study which considers the age of the pecorino. I seem to have an easier time of getting the proper emulsion with older drier pecorino, and less risk of clumping

[dboreham]

Costco peccorino works well.

[saagarjha]

I’m going to be upset if this doesn’t win an Ig Nobel

[Oarch]

Only 4 days into 2025 and we've already found the winner. At ease, HN.

[dwattttt]

It's a shoe-in

[smegger001]

I mean its good but is it to the Ig Nobel level?

I mean its no "Homosexual Necrophilia in the Mallard Anas Platyrhynchos"

[neom]

I've made a lot of Cacio e Pepe over the years, the best video on the subject is Ethan Chlebowski imo. Ethan Chlebowski videos are generally REALLY great.

https://www.youtube.com/watch?v=10lXPzbRoU0

[serial_dev]

I prepared this dish a couple of times, the second time I randomly got lucky and made a great cacio e pepe, since then all my attempts turn out clumpy, “mozzarella-like” and not creamy.

No matter how many videos I watched, I could never make it well enough.

I’m glad someone got to the bottom of this issue.

[dboreham]

You had the temperature too high. I use an IR thermometer. Nonna from the old country just knows how long to wait for it to cool down enough which is why it looks like magic easy in their YouTube videos.

[ggm]

Subjects: Soft Condensed Matter

This has to be targeting igNobels

[larodi]

I must admit, the paper inspired me cook a pasta as close as possible to suggestions, together with Claude ingesting the PDF and the result was really good.

Thanks, physics PHDs!

[marsavar]

"We thank Tetsuya Spippayashi for enlightening clarifications on the historical origins of Cacio and pepe"

That surname can't be real...

[dismalaf]

Probably a bad transliteration.

[bdauvergne]

Conlusion: just add some (possibly cooked) flour to your sauce. It's called "singer" in French.

[sebtron]

The authors suggest corn or potato starch, not flour.

[mastazi]

In Italy we just add to the pan some of the water in which the pasta was cooked; this is rich in starch due to the cooking process. This works with other recipes as well, for example gricia or aglio olio & peperoncino. I guess that adding flour would produce a texture more similar to gravy and that's not what we're going for in traditional Italian cooking.

[paultopia]

Cooking would suck a lot less if physicists who cared about clarity and precision wrote recipes.

[ziofill]

The main trick (to add cornstarch in order to achieve the right creaminess) is good for lots of recipes where you have milk/cheese and you want to make it creamy. It's a real ace up the cook's sleeve.

[douglee650]

Someone get these guys hooked up with lasagna manifolds https://web.stanford.edu/~cm5/lasagna.pdf

[nimish]

This is the real hacker news. More of this!

We need more curiosity about things :)

[andreagrandi]

corn... potato starch......... WTH?!

Ohh... I know what you did here!

Someone needs to train their LLMs with original italian BESTEMMIE and posted this link to encourage Italian people to write a lot of them.

Smart move :)