Should You Use Calcium Chloride When Making Mozzarella?

Stretching Mozzarella

Lately, online cheesemaking forums have been abuzz with controversy over the question of whether calcium chloride should be used when making mozzarella. Some folks insist that calcium chloride is necessary for proper curd formation, and others argue that it prevents the curds from stretching.

So, who’s right?

To get to the bottom of this controversy, we turned to world-renown cheesemaker Margaret Morris, author of The Cheesemaker’s Manual, 2015 winner of First Prize at the American Cheese Society (ACS) Society, and 2013 winner of the top award at the Global Cheese Making Competition in Somerset, UK.

Here’s what we learned.


You can make mozzarella the traditional, old fashioned way, or you can use a method that takes much less time. The chief difference between these two methods is the process you use to lower the pH of the milk. Lowering the pH creates the acidic environment needed to form curd.

The traditional method uses rennet and cheesemaking cultures. These natural ingredients lower the pH of the milk gently and slowly, which imparts better flavor and other finer qualities in the finished cheese.

By contrast, with the fast method, the pH of the milk is lowered very rapidly. This method circumvents the need for cheese cultures and instead uses citric acid in combination with the rennet. This is similar to the process most commercial cheesemakers use. You can use citric acid to make mozzarella at home, too, but we don’t recommend it if you are looking for wonderful flavors.


With the traditional method, rennet and cheese culture work in tandem to lower the pH of the milk, provided that adequate calcium is present. Calcium availability becomes an issue when using commercial brands of store-bought milk that have been pasteurized (or ultra-pasteurized). Pasteurization not only kills potentially harmful bacteria, but also damages the vitamins, minerals and other nutrients originally contained in the milk, which renders the natural calcium unavailable for making curds. So, when using store-bought milk, you need to supplement your milk by adding calcium chloride.  Doing so ensures that adequate calcium is available for natural curd formation to occur.

On the other hand, raw milk has not been damaged by pasteurization and retains all its original nutrients. Because raw milk already contains plenty of available calcium naturally, there’s no need to add calcium chloride to encourage curd formation.

Unlike the traditional method, which uses cheese cultures, the fast method relies on citric acid to work with the rennet. It takes much less time to make mozzarella this way because citric acid causes an instant, sharp drop in the pH of the milk. This forces curds to form very rapidly, regardless of what type of milk you’re using—pasteurized or unpasteurized.

If you were to add calcium chloride at this point, the pH would drop even lower—far below the level necessary to form curds. When the milk becomes too acidic, curds lose moisture. And when curds dry out, they tend to crumble instead of stretching.

So now you see why there’s been so much confusion about calcium chloride on the cheesemaking forums. Folks are getting different results because they’re using different methods to make their mozzarella. And those who claim that adding calcium chloride prevents curds from stretching are experiencing this problem because they’re using it in combination with citric acid.


If you follow these simple rules, your mozzarella will stretch every time:

  • Add calcium chloride when using rennet and cheese culture with store-bought (pasteurized) milk.
  • DO NOT add calcium chloride when using rennet and cheese culture with raw milk.
  • DO NOT add calcium chloride when using citric acid and any type of milk.


It can take a couple of hours to make mozzarella the natural, old-fashioned way; however, the result is an exceptional cheese that’s well worth the time spent. Mozzarella made this way tastes better because the cheese cultures impart superior flavor and texture.

Cheese cultures are a special collection of freeze-dried, health-promoting bacteria strains that you add to the milk when making cheese. A wide variety of cheese cultures are used in cheesemaking. Each recipe calls for a particular type of culture, as well as specific temperatures and timing. Together, these factors determine the flavor and texture of each cheese.

Using cheese culture does increase the cost of making cheese a bit, but part of the fun is trying a variety of cultures to see which kind you prefer. At Homesteader’s Supply, we offer an Italian Mozzarella Kit that contains cheese cultures imported from Italy, and we give you an authentic recipe. So when you use our kit, you get a real Italian mozzarella with real “Old World” flavor!

HS Italian Mozzarella Kit

On the other hand, if you use citric acid instead of cheese cultures, you can make mozzarella in half an hour. Other places sell those kits, which are less costly up front. You pay less because citric acid is much less expensive than cheese cultures. But, keep in mind that only a tiny amount of cheese culture is needed for each batch. So when you buy a cheesemaking kit from us, such as our Italian Mozzarella Kit, you get enough cheese culture to last you quite a while—and you can use it to make other types of cheeses, and even butter!

By the way, with the fast method, you could get a similar result by substituting a different kind of acid for the citric acid. For example, you could use vinegar or lemon juice. But, know that these types of additives leave their mark on the cheese. And you can taste the difference. That’s why commercial cheesemakers often use salt and other flavor enhancing additives.


We’ve shown you two different ways of making cheese. Technically, both methods produce mozzarella, but it should be obvious by now that not all mozzarella is created equal.

Cheese is like life in that there are no shortcuts to success. Sure, the fast method will save you time—but the flavor and quality of the cheese will be compromised. For a superior product, make your mozzarella the old fashioned way. Natural cheeses made with rennet and cheese cultures have incomparable flavor, age better, and last longer. You’ll never regret the extra time it took to create a truly superb cheese.