The Different Types of Rennet in Cheesemaking
Rennet is a crucial component in cheesemaking, containing enzymes that cause milk to coagulate, separating it into solid curds and liquid whey. While the result—coagulation—is the same, the source of these enzymes can differ significantly. Understanding these sources is key to knowing whether a cheese like mozzarella contains animal products.
Historically, rennet was obtained from the fourth stomach lining of young ruminant animals, such as calves, lambs, and kid goats. This is what is meant by "animal rennet" and it is still used today, particularly in traditional, artisanal, or specialty cheeses. In fact, some cheeses, like true Parmigiano-Reggiano, are required by law to use animal rennet.
However, due to ethical concerns, rising demand for cheese, and the limited supply of animal rennet, alternatives were developed decades ago. These include:
- Microbial Rennet: Produced by fermenting specific types of molds or fungi, like Rhizomucor miehei. This is a very common, vegetarian-friendly option for many commercial cheeses, including mozzarella.
- Fermentation-Produced Chymosin (FPC): Created using genetically modified microorganisms, such as yeast, to replicate the chymosin enzyme found in calf rennet. FPC is chemically identical to animal chymosin but is vegetarian and widely used in large-scale production, accounting for a huge portion of cheese production globally.
- Plant-Based Rennet: Derived from plants with coagulating properties, such as thistle, artichokes, or fig leaves. While a vegetarian option, it is less common for commercial mozzarella and can sometimes lead to a bitter flavor in aged cheeses.
Traditional vs. Commercial Mozzarella: What’s the Difference?
When asking, "Is mozzarella ever made with animal rennet?", the specific type of mozzarella is the most important factor. The answer changes significantly depending on whether you are referring to fresh, traditional mozzarella or the shredded, low-moisture version commonly found on pizza.
Traditional Mozzarella (Mozzarella di Bufala)
In Italy, traditional mozzarella, especially the type made from water buffalo milk (mozzarella di bufala), can be made with animal rennet. For cheesemakers adhering to ancient traditions or those with protected designation of origin (PDO) status, using animal rennet is standard practice. Consumers buying high-end, imported fresh mozzarella should be aware that it might not be vegetarian.
Commercial Mozzarella (Shredded, Low-Moisture)
The vast majority of mozzarella produced for pizza, lasagnas, and other dishes is mass-produced and uses vegetarian alternatives. The global shift towards microbial and FPC rennet in the late 1970s and 1980s was driven by the surge in popularity of pizza and the need for a cheaper, more abundant source of coagulant. This means that the shredded mozzarella you buy at a typical grocery store is almost certainly vegetarian.
How to Identify the Rennet Source
For conscientious consumers, especially vegetarians, knowing how to determine the rennet source is vital. Here is a guide to navigating the options.
1. Check the Label
- Look for terms like "microbial enzymes," "vegetarian enzymes," "non-animal rennet," or "vegetable rennet". If any of these are listed, the cheese is safe for vegetarians. Many manufacturers now proudly label their cheese as vegetarian.
2. Understand "Enzymes"
- If the ingredient list simply says "enzymes," the source is not specified. In many countries, including the U.S., manufacturers are not required to disclose the source. In this case, you should assume it could be animal-derived, or take the next step.
3. Contact the Manufacturer
- If the label is unclear, visiting the company's website or calling their customer service line is a reliable way to find out. Many brands, like Belgioioso, specify their use of microbial rennet on their website.
4. Look for Certifications
- Certified kosher cheeses will always be vegetarian, as they are prohibited from using animal rennet. Some organic products also avoid FPC because it uses genetically modified organisms (GMOs) in its production process.
Mozzarella Rennet Comparison Table
| Feature | Animal Rennet | Microbial Rennet | FPC Rennet |
|---|---|---|---|
| Source | 4th stomach of young calves or lambs | Fermentation of specific molds/fungi | GMOs (bacteria, fungi, yeast) |
| Vegetarian-Friendly? | No | Yes | Yes |
| Availability | Limited; used in artisanal cheese | Widespread; standard in commercial cheese | Extremely Widespread; dominates industry |
| Flavor Impact | Clean flavor, optimal for aging | Generally neutral, but can cause bitterness in aged cheese | Chemically identical to animal chymosin; neutral |
| Cost | Expensive | Less expensive than animal rennet | Least expensive; highly cost-effective |
What About Other Mozzarella Variations?
While most commercial cow's milk mozzarella is vegetarian, some traditional or regional variations should be considered. For example, some sheep's milk mozzarella (mozzapecora) from Italy uses lamb rennet. Similarly, some small-batch, specialty producers may opt for animal rennet for its traditional flavor profile, especially if they are making fresh mozzarella.
For those who wish to avoid dairy entirely, there are numerous vegan mozzarella alternatives made from plant-based ingredients like cashews, soy, and tapioca starch. These options offer a similar texture and melting properties for various dishes.
Conclusion
To answer the question, "Is mozzarella ever made with animal rennet?", the response is that it can be, particularly in traditional Italian varieties and artisanal products. However, the vast majority of commercial, mass-produced mozzarella, especially the low-moisture kind found in most grocery stores, is made with vegetarian-friendly microbial or FPC rennet due to changes in industry practices. The key for consumers is to be vigilant and check product labels for confirmation or, when in doubt, to contact the manufacturer. For a deeper understanding of cheesemaking techniques, explore the informative resources from organizations like Wisconsin Cheese.
