Have you ever wondered what goes into making your favorite mozzarella cheese? Well, one of the most critical ingredients in the process of making mozzarella cheese is rennet.

Rennet is a mixture of enzymes that are used to coagulate milk and turn it into curd. But, is rennet used in all mozzarella cheese? Let’s find out.

What is Rennet?

Rennet is a complex mixture of enzymes that are found naturally in the stomachs of young mammals, including cows, sheep, and goats. The enzymes help young mammals digest their mother’s milk by coagulating it into curd. The curd then separates from the whey, which allows the young mammal to easily digest the milk.

How is Rennet Used in Cheese Making?

In cheese making, rennet is added to milk to coagulate it and form curds. The curds are then separated from the whey and processed further to make different types of cheeses like cheddar, parmesan, and mozzarella.

Is Rennet Used in Mozzarella Cheese?

Traditionally, animal-based rennet was used to make mozzarella cheese. However, due to concerns over animal welfare and dietary restrictions for vegetarians and vegans, many manufacturers now use microbial or vegetable-based rennet instead.

Microbial Rennet

Microbial rennet is produced by fermenting a specific strain of bacteria called Rhizomucor miehei. This type of rennet produces an enzyme called chymosin that has similar coagulating properties as animal-based rennet.

Vegetable Rennet

Vegetable rennet is made from a variety of plant sources like thistle or fig leaves. These sources contain enzymes that can coagulate milk and are used as a substitute for animal-based rennet.


In conclusion, while traditional mozzarella cheese making involves the use of animal-based rennet, many manufacturers now offer vegetarian and vegan options that use microbial or vegetable-based rennet. So, the next time you buy mozzarella cheese, make sure to read the label and choose the type of rennet that aligns with your dietary preferences.