Mozzarella's Core Ingredients: Milk and Coagulants
Authentic Italian mozzarella, mozzarella di bufala, comes from the milk of the Italian Mediterranean water buffalo. Most mozzarella sold worldwide is made from cow's milk. The process involves curdling milk, which requires a coagulating agent.
The Role of Rennet in Mozzarella Production
Cheesemakers have used rennet for centuries to curdle milk. Rennet is an enzyme, mainly chymosin, found in the fourth stomach lining of young, milk-fed ruminant animals such as calves, lambs, and goats. Rennet causes the protein casein to coagulate, separating the milk into curds and whey.
The traditional form of rennet comes from ruminants, not pigs. This is why mozzarella does not contain any pork. Confusion can come from the term "animal-derived enzymes" and its use in other cheese or food products.
Modern Alternatives to Traditional Animal Rennet
Because of the traditional source of rennet, people following a vegetarian diet or specific religious dietary laws must be mindful of the coagulant used. Manufacturers use alternative, non-animal-derived rennets:
- Microbial Rennet: Produced via fermentation of specific fungi or bacteria, this is a vegetarian alternative.
- Fermentation-Produced Chymosin (FPC): This is a bio-engineered form of chymosin, identical to the calf-derived enzyme but made using genetically modified microorganisms. It is also suitable for vegetarians.
- Vegetable Rennet: Derived from plants like the thistle or cardoon, this type of rennet is vegetarian-friendly.
Industrial mozzarella, especially low-moisture varieties used for pizzas, frequently uses these alternative rennets for consistent results and to serve vegetarian markets.
Clarifying the Confusion: Pork in Cheese and "Head Cheese"
Speculation about pork in cheese often stems from these misconceptions:
- The 'Head Cheese' Mix-Up: "Head cheese" is not a dairy product, but a meat terrine or pâté made from the head of a pig or calf, congealed in its own gelatin.
- American Cheese Products: Some older or cheaper American cheese products have used non-ruminant animal enzymes, which could include porcine sources. This is not a factor for mozzarella, and most producers have switched to non-animal alternatives.
Comparison of Rennet Types in Cheese Production
This table compares the most common types of rennet.
| Feature | Traditional Animal Rennet | Microbial Rennet | Fermentation-Produced Chymosin (FPC) |
|---|---|---|---|
| Source | Stomachs of young ruminants (calf, lamb) | Fungi and bacteria through fermentation | Genetically modified microorganisms |
| Vegetarian-Friendly? | No | Yes | Yes |
| Halal/Kosher Concerns? | Yes, if not from correctly slaughtered animals | No | Generally accepted, but certification is key |
| Flavor Impact | Clean, traditional flavor; preferred for aged cheeses | Can produce bitterness in aged cheeses; neutral in fresh cheeses | Identical in function to calf rennet, with neutral flavor |
| Usage | Traditional, artisan, and some aged cheeses | Common for vegetarian and kosher cheeses, especially fresher types | Widespread in modern, large-scale cheese production |
Conclusion: How to Ensure Your Mozzarella is Pork-Free
A pure mozzarella, made only from milk, starter cultures, and coagulant, is not made from pork. The milk—buffalo or cow's—is dairy-based. The potential for animal byproducts comes from the type of rennet used.
Examine the product label for the type of coagulant used. Look for terms like "microbial enzymes," "vegetarian rennet," or a specific halal or kosher certification. The mozzarella used for pizzas, pasta, and salads is a dairy product, free from any porcine ingredients. Learn more about the different types of rennet at ScienceDirect.
