Making Fresh Mozzarella: Temps and Times Matter!

If you’ve ever had the delicious privilege of eating a properly-made Pizza Margherita or a garden-fresh Caprese salad, then you have known the joy that simple, fresh mozzarella cheese can bring. It’s really quite good.

But, of course, it’s not readily available in every place. And if you are seriously into cooking and you made your dough from scratch and you made your sauce from scratch and you grew your own basil, well, then making your own mozzarella seems like the next step, right? If you’ve ever wanted to wade safely into the world of cheese making—without investing in an aging system or a curd press—making fresh mozzarella is a fantastic path to take.

Cheesemaking is intensely temperature-sensitive, so we’ll lay out the tools and temps you need to get it right as we follow the method published by Epicurious.

What is fresh mozzarella?

Mozzarella is an Italian cheese from the region surrounding Naples. It is the most well-known version of what the Italians call pasta filata, meaning spun paste. In English, we use the term stretched-curd or pulled-curd cheese, but the meaning is the same. Curds are cooked and heated, then stretched together and pulled repeatedly to make a cheese that is fibrous and somewhat elastic.

(Mozzarella doesn’t have the corner on the market for this method, though. Mexican queso de Oaxaca (locally called quesillo) is a very similar sister to fresh mozzarella but is rolled into what looks like a ball of string, with pieces unraveled and cut or torn off for use. Balkan Kashkaval is another pulled-curd cheese, as is real provolone.)

In Italy, mozzarella was originally made with the milk of an Italian breed of water buffalo (mozzarella di bufala). In the States, that’s harder to come across—and even harder to make from scratch—but if you ever get the chance to try some, certainly take advantage of the opportunity. It’s delicious.

Nowadays most mozz is made with moo milk, and most mozz is low-moisture, which is to say it’s the brick mozzarella that you grate off of a block. While that blocky cheese is also made by flexing and plasticizing the curds, it just doesn’t have the same texture and fun as the fresh stuff. Here, we want the original, fresh mozzarella.

How is fresh mozzarella made?

If I were to answer the question of how mozzarella is made in one sentence it’d probably be this: Fresh mozzarella is made by acidifying milk and coagulating it with rennet, then kneading and pulling the resulting curds in a hot water bath. Of course, that’s not nearly enough to go on, so let’s break it down.

Acidifying the milk for cheese

First, acidification. All cheeses undergo a process of acidification, either by the direct addition of an acid, as is done in this case, or by the action of lactic acid bacteria that consume lactose (the natural sugar found in milk) and produce lactic acid. The world of cheese-making bacteria is a fascinating and complex one, but one upon which we will not touch here, as it is irrelevant to our current project. We will use citric acid for our acidification. That direct acidification is one reason why mozzarella is a great cheese for first-time cheese makers:

Direct acidification is more controllable than biological acidification, and, unlike starters, it is not susceptible to phage infection. However, in addition to acidification, the starter bacteria serve very important functions in cheese ripening, and hence chemical acidification is used mainly for cheese varieties for which texture is more important than flavor.

—Patrick F. Fox, et al, Fundamentals of Cheese Science, pg 14

Another word for acidification is curdling. If you’ve ever put vinegar or lemon juice into milk, you know how it will curdle, going from a smooth liquid to a chunky mass. While that is unpleasant for drinking milk, it’s completely necessary for making cheese. The curdling step will prepare the milk for the coagulation step, so it’s important to get right.

To curdle the milk, a solution of citric acid in water is stirred into the milk before the milk is heated. As the milk heats up with the acid mixed into it, the proteins start to denature—that’s the curdling—preparing the liquid for the coagulant to work. This is the first time that you’ll need to reach for a thermometer in this process, but it won’t be the last. Use your Thermapen^® to check the milk as it slowly heats up to 90°F (32°C). That’s when you want to add the coagulant.

Coagulation in cheese making

Cheese is more than just curdled milk. It’s firmer, has more structure, more bite to it. That’s where coagulation comes in. Coagulation is the process whereby the free proteins bond to each other, causing a more solid network. Certain milk proteins, caseins, usually have an outer coating of charged protein strands that repel them from each other. When the coagulant goes to work in the milk, its enzyme shaves off those charged proteins, allowing the caseins to bond to one another and form chains. Those chains trap fats and water and create a more solidly-textured substance than curdling alone.

The coagulant we use for cheese making is rennet, which is an enzyme that was originally derived from the linings of young cow, sheep, and goat stomachs, though that is rarely the case now.

Now[…]modern biotechnology produces a pure version of the same calf enzyme called chymosin, in a bacterium, a mold, and a yeast. Today, most cheese in the United States is made with these engineered “vegetable rennets,” and less than a quarter with traditional rennet from a calf stomach.”

-Harold McGee, On Food and Cooking, pg 56

(Some vegetable rennets are also derived from cardoon thistles, but they are only used in sheep and goat cheeses.)

You can buy liquid rennet online or, usually, at your local home-brew store. It is also available in tablet form, which can usually be found near the gelatin in most grocery stores. In this recipe, we will use liquid rennet.

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Once the milk has been properly acidified and curdled, remove it from heat and add the rennet (diluted with some water for better dispersion in the milk), stirring it in. The stirring must be very thorough—stir for a full 30 seconds. Cover the pot and let it stand, off the heat, for five minutes. (An Extra Big & Lound timer is a handy way to track the coagulation time.)

After five minutes, check the cheese. It should have a gelatinous texture and should be able to pull away from the edges of the pot. The milk is now ready to cut into curds. (If it has not yet coagulated to that point, set it aside for another five minutes. This could happen based on various factors, from rennet strength to the milk itself.)

Cooking the mozzarella curd

What you have produced by coagulation is called by experts a “milk gel,” and it is quite stable for what it is. But once you cut it, the network of casein proteins breaks and the trapped liquids held within the chains will quickly leak out. This semi-milky liquid is, of course, whey, and the gel-like pieces from which it empties are now called curds. This water expulsion concentrates the fats and proteins in cheese by up to 12 times from their concentration in milk. Different cheese curds are cut in different ways, based on how they were coagulated and how they will be handles later on. Mozzarella curds are cut roughly 1/2-inch square.

Cut the milk gel into curds with a thin spatula or a knife (even a butter knife will do). Cut a 1/2-inch cross-hatch pattern into the gel. You will immediately see that the whey begins to pour out of the curds. This is good.

The curds now need to be cooked. Cooking the curds will tighten the proteins, making them expel more whey and water from within their networks, much like what happens when you overcook a steak. We don’t want to cook the curds too far, however. Put the pot of curds and whey back on the stove over medium heat. use your Thermapen to track the temperature as you heat the pot—gently stirring it occasionally—up to 105°F (41°C). Once you get to temp, take the pot off the heat and let it sit for another (timer-measured) five minutes.

Use a fine-mesh strainer to separate the curds from the whey. Let them drain some. Put the pot of whey back on the stove. It’s time for the stretching.

Stretching mozzarella curd

Fresh mozzarella is partly about the flavor—milky, fresh, with a slight tang to it. 4 But it is equally about the texture, and that texture comes from kneading and pulling the curds. Let’s take a look.

While the curds are draining in their sieve, put the pot of whey back on the stove and start heating it. Use your Thermapen to measure the temp as you heat it, aiming for 185°F (85°C). This part can get pretty hot, so I recommend wearing some cotton gloves for insulation underneath some waterproof gloves. Lower the strainer full of curds into the hot water for a minute or so. Fold the curd over onto themselves a few times, then check to see if they’ve reached 135°F (57°C). If not, return them to the hot water.

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Once the curds have reached their target temp, it’s time to knead them. Remove the curds from the whey pot, salt them lightly, and start folding them in on themselves. Fold and stretch, fold and stretch, fold and stretch again. If the cheese gets too cold or starts to tear easily when you stretch it, put it back in the pot for a few moments, then continue to fold and stretch. It’s quite fun!

Once you have stretched it and folded it several times, it will have a springy, almost elastic feel and should be quite smooth in texture. Now you can shape it how you like. Cut pieces of and fold them in on themselves to make large balls, roll the whole thing into a log and cut it into sections, or do as I did and hold the mass in one hand and extrude a piece up between your thumb and forefinger, pinch it between those digits and twist it off with your other hand. If you like, stretch the cheese into long strands and wrap them up like a yarn ball for Oaxacan quesillo.

If you aren’t going to eat your cheese immediately, store it in a container of cooled whey, perhaps with a little bit of salt.

Ok. I know that was a lot. But when you get down to it, it’s heating, mixing, resting, cutting, stirring, scooping, kneading. You can do that. And with your Thermapen^® and your Extra Big & Loud Timer at your side, you can do it with confidence. The first time I made mozz, it didn’t go great. I was following old-school instructions that didn’t tell me anything about actual temperatures. But you don’t have to relive my struggle. Use these temps, maze some fresh cheese. Happy cooking!

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