This post is the first post in a two-part series. In this post, we explain the science behind our carbonara recipe. If you want to skip the science and go straight to the recipe, click here.

Carbonara Science Explained: Emulsions, Starch and More

Although Carbonara is a simple dish, achieving the perfect version can be surprisingly challenging. It’s difficult to get the eggs just right. I usually end up with either undercooked eggs and a soupy sauce, or a scrambled egg sauce.

However, what if we opt not to use eggs?

Is it possible to swap out the eggs for some other ingredients, and still make a great carbonara?

The answer is yes. In this post, we’re going to explore exactly that. Carbonara science isn’t something we learn in cooking classes, but in this post we’re going to dive into the science of carbonara to understand what exactly the eggs do. Then we’ll use that understanding to replace the eggs with other ingredients that do the same thing.

But before we do any of that, let’s remind ourselves how a traditional carbonara is usually made.

Carbonara is traditionally made with just five ingredients:

• Hard cheese (e.g. Pecorino, Parmesan, etc)
• Eggs
• Pasta
• Cured pork (e.g. pancetta or guanciale)
• Black pepper

To begin, you cook the pasta in seasoned water until it reaches an al dente texture. Meanwhile, you mix a few eggs with some black pepper and grated cheese. You cook the bacon on a low heat until the fat renders, then you mix in the pasta (with the water) to form an sauce from the bacon fat and pasta water. You then turn off the heat and mix in the egg, pepper and cheese to form the carbonara sauce.

That’s it. With those simple steps, you’ve got a bog-standard, traditional carbonara.

However, this method of preparing carbonara is inherently precarious. The eggs can easily scramble, turning that velvety sauce into a coagulated, starchy mess.

But this can be avoided. To do that, we first need to understand the science of the carbonara.

The Science of Emulsions

Carbonara science isn’t rocket science. At its most basic, a carbonara sauce is just an emulsion. But what exactly is an emulsion?

Well, there are some liquids that just naturally don’t mix together. If you try to mix together oil and vinegar, they’ll quickly separate.

This happens because fat and water (in this case, oil and vinegar respectively) do not mix together. But if we give that mixture a firm shake, it’ll form a creamy cohesive sauce.

When you force together two liquids that usually don’t mix, as described, you’ve made an emulsion. In this case, we’ve made a basic vinaigrette.

But it won’t take long for the oil and vinegar to separate again. That’s because there’s nothing forcing the liquids to stay together. They’ll begin separating the moment you stop mixing them. We’ve only created a temporary emulsion.

But there is a way to stop the liquids from separating permanently – we need to create a permanent emulsion.

If you add a small amount of mustard to the mixture and shake it up again, this time the emulsion will stay together. The reason this happens is because mustard contains certain molecules that can attract both water and fat. It acts like a glue that holds the oil and vinegar together. We call ingredients with these properties emulsifiers, and mustard is just one example. There are hundreds of synthetic and natural emulsifiers, including eggs.

When you add an emulsifier to a temporary emulsion, you create a permanent emulsion.

As mentioned, a carbonara sauce is also just an emulsion. In this case, it’s an emulsion between pasta water and egg.

Eggs are a great ingredient to use in emulsions. Alongside hundreds of proteins and various nutrients, eggs also contain plenty of fat and a natural emulsifier called lecithin.

That means an egg provides two of the three ingredients we need to make an emulsion: the fat and the emulsifier. In fact, both the fat and the lecithin are mainly concentrated in the egg yolk. So we can actually make the carbonara sauce without the egg whites. Using just egg yolks will give us a richer, thicker sauce.

All we need to do to make an emulsion is mix the egg yolk with something water-based, like, for example pasta water.

But a carbonara sauce isn’t just made up of egg and water. There’s one more ingredient: starch. (Nobody said carbonara science was simple!)

The Science of Starch

Pasta water isn’t just “regular” water.

As we all probably know, pasta water is much cloudier than normal water.

That’s because the pasta water is full of the starch that the pasta has released into the water as it’s cooked. The reason this starch is important for us is because it thickens our sauce.

You’ve probably used cornflour before to thicken sauces or soups. Well, the starch from pasta basically does the same job. The more starch we use, the thicker our carbonara sauce will be. However, pasta can only release so much starch into the water. When you’re boiling pasta, for any given amount of pasta, the more water that you use, the more diluted its starch content will be. In other words, more water means less starch, and less starch means a thinner sauce. The key to getting as much starch as possible from your pasta is to use as little water as possible.

So that’s how a carbonara sauce is made. It’s an emulsion between pasta water and the fat from the egg, held together by the egg’s natural emulsifiers and thickened by the pasta starch.

An eggless carbonara?

As we’ve learnt, eggs provide two important things to a carbonara: fat and lecithin.

With that theory in mind, it is pretty straightforward to make an eggless carbonara. By substituting the egg’s fat and lecithin with alternative ingredients, we can still achieve similar results. (Obviously the taste will be different, but we will still have a creamy and rich sauce).

There are loads of combinations that we could use:

• Alternative fats: olive oil, rendered animal fat (e.g. tallow), coconut oil, etc.
• Alternative emulsifiers: tomato puree, mustard, xantham gum, guar gum, etc.

Follow the same steps outlined above (or in the recipe below) but replace the eggs with a new fat and emulsifier and viola – you’ll still have a carbonara.

How’s that for carbonara science?

Putting the carbonara science into action: a fool-proof carbonara recipe

But if you do still want to have eggs in your carbonara (because, come on, who doesn’t?) then we can still leverage an understanding of the science of the carbonara recipe to make a fool-proof carbonara.

As we’ve already talked about, the real challenge of a traditional carbonara is temperature control. We need to cook the eggs just enough to form a tight sauce but not so long that the eggs scramble. So how can we achieve that? First, we need to get rid of the egg whites.

Eggs are mainly made up of protein, but eggs aren’t made up of just one kind of protein. They’re made up of dozens of different proteins, and different proteins have different denaturing and coagulation temperatures. The proteins that are in the egg whites are different from the proteins in the egg yolks. Those in the egg yolks actually denature at a higher temperature than those in the egg whites.

That means if we remove the egg whites from the sauce, we increase the sauce’s coagulation temperature and, in turn, increase our margin for error.

Second, we need to make sure that we’re only adding the egg and cheese mixture to the pan when the pan is off the heat. If we rely on the direct heat from the hob’s burner, we’d have to keep a very close eye on the pan to make sure that the eggs don’t coagulate and scramble.

If we instead only add the mixture to the pan while it’s off the heat, we can gently cook the eggs using the heat of the pasta, the pasta water, and whatever heat is left in the pan. This massively reduces the chances of the eggs scrambling.

Third, and most importantly, we need to add our hot pasta water to the egg and cheese mixture directly, instead of adding it to the pan. Now, this might sound inconsequential, but if we do it this way around, we can reduce the chance of the egg scrambling.

As we’ve already discussed, as we cook an egg, its proteins begin to latch onto one another. But if we dilute the egg mixture with other ingredients, we’re literally adding more space between the proteins. And by doing this, it makes it harder for the proteins to grip each other as they unfold. And that’s simply because they’re further away from each other. This, in turn, increases the time it takes for the eggs to coagulate.

Think about it like this: it’s a stupid example, but imagine two people trying to hug each other. If they’re right next to each other, they’ll be able to hug each other straight away with no problems. But now imagine there are loads of people between them. It’s going to be a lot harder for them to make contact, right? Of course, where there’s a will, there’s a way. They will hug eventually, but it’ll just take them more time to reach each other.

In the same way, when we dilute the egg with other ingredients, we’re making it harder for the proteins to make contact. They will eventually still coagulate. We can’t stop that from happening. But by diluting the mixture, we’re increasing the time it takes for that to happen, further increasing our margin for error.

By leveraging all these tricks, making a fool-proof carbonara becomes, well, fool-proof. Don’t believe me? Try it yourself.