Which Cheeses Have Rennet in Them? Your Guide to Rennet-Made Cheeses

January 13, 2026 •

4 min read

An enzyme called rennet is a key ingredient in cheesemaking, used for milk coagulation. Rennet has historically come from the stomachs of young ruminant animals. Today, cheeses are made with animal, microbial, or plant-based rennet.

Quick Summary

Rennet, used to curdle milk, comes from animal, microbial, or plant sources. Traditional cheeses such as Parmesan and Gruyère use animal rennet, while many commercial cheeses use vegetarian alternatives. Check labels for specific rennet types.

Key Points

Animal Rennet Source: Traditional rennet comes from the stomachs of young ruminant animals, such as calves and lambs.
Vegetarian Alternatives: Vegetarian cheeses use alternatives like microbial rennet (from fungi) or FPC rennet (genetically engineered chymosin).
Traditional Cheeses: Authentic European cheeses like Parmigiano-Reggiano, Gruyère, and Pecorino Romano often require animal rennet.
Labeling is Key: Look for terms like "microbial enzymes," "vegetarian rennet," or certification marks like kosher or vegetarian to identify non-animal rennet cheese.
Vague Labels: If a cheese label only lists "enzymes" or "rennet," assume it is animal-based unless a vegetarian certification is present.
Rennet-Free Cheeses: Some fresh cheeses like ricotta and paneer are made by acid coagulation and do not use rennet.

The Role of Rennet in Cheese Production

Rennet is a vital component in the process of cheesemaking, causing milk to coagulate into solid curds, separating from the whey. Chymosin, the active ingredient in rennet, causes milk proteins (casein) to clump, forming the solid mass that's processed into cheese. While traditionally derived from young ruminant stomachs, cheesemaking today uses a variety of rennet types.

Types of Rennet

Understanding the different rennet sources helps in identifying which cheeses use it. The main types include:

Animal Rennet: This traditional form is extracted from the stomach lining of young mammals like calves, lambs, and kids. Cheeses made with animal rennet are not vegetarian.
Microbial Rennet: Produced by fermenting specific fungi or molds, this is a vegetarian-friendly alternative to animal rennet. It is widely used in commercial cheesemaking.
Fermentation-Produced Chymosin (FPC): This advanced type of microbial rennet is created by inserting a calf's chymosin-producing gene into yeast or bacteria. The resulting enzyme is identical to animal chymosin and is considered vegetarian.
Plant-Based Rennet: Extracted from plants such as cardoon thistle, figs, or nettles, this rennet type is used in certain artisanal and traditional cheeses, especially in the Mediterranean. Its effectiveness and flavor profile can be less consistent than other types.

Cheeses Commonly Made With Animal Rennet

Many classic European and aged cheeses traditionally or legally require animal rennet. Vegetarians should avoid the authentic versions of these cheeses and seek out vegetarian alternatives.

Here are some of the most well-known cheeses that typically contain animal rennet:

Parmigiano-Reggiano: Authentic Parmigiano-Reggiano from Italy legally requires the use of animal rennet.
Pecorino Romano: This hard Italian cheese is also traditionally made with animal rennet.
Gruyère: The traditional version of this Swiss cheese is made with animal rennet.
Gorgonzola: This Italian blue cheese often contains animal rennet.
Manchego: The protected designation of origin (PDO) version of this Spanish cheese uses animal rennet.
Grana Padano: This Italian cheese with a PDO mandates the use of animal rennet.
Emmentaler: While some dairies use microbial rennet, many traditional Emmentaler producers use animal rennet.

Cheeses That May Use Either Type of Rennet

With the rise of vegetarianism, many cheesemakers use microbial or other vegetarian rennet alternatives. Reading the ingredient label or looking for vegetarian certification is essential.

Cheddar: Aged artisanal cheddars often use animal rennet. Many commercial brands use microbial enzymes.
Mozzarella: Traditional, fresh mozzarella can be made with animal rennet, but most commercial versions use microbial rennet.
Feta: The rennet type in feta varies by brand and origin. Some traditional recipes use animal rennet, while producers now use microbial rennet.
Swiss Cheese: Many modern Swiss cheese varieties may use microbial rennet, though traditional versions might use animal rennet.
Goat's Cheese: While many traditional French goat cheeses use animal rennet, British and modern producers often use a vegetarian-friendly option.

Comparison of Rennet Types in Common Cheeses

This table provides a quick reference for cheeses and their traditional or potential rennet content.


Cheese Type	Traditional Rennet Source	Common Rennet Type in Modern Production	Vegetarian-Friendly Version Available?
Parmigiano-Reggiano	Animal (Calf)	Animal	No (authentic version)
Pecorino Romano	Animal (Lamb)	Animal	Look for microbial versions
Gruyère	Animal	Animal	Look for microbial versions
Gorgonzola	Animal	Often Animal	Yes, look for microbial versions
Cheddar	Animal	Microbial or Animal	Yes, many mass-produced brands
Mozzarella	Animal	Microbial	Yes, widely available
Feta	Animal	Microbial or Animal	Yes, check labeling

How to Determine If Your Cheese Uses Animal Rennet

Identifying the rennet type can be challenging because labeling is not always explicit. Here's how to check:

Check the Label: Vegetarian cheeses are often labeled with phrases like "vegetarian rennet," "microbial enzymes," or "non-animal rennet".
Avoid Vague Terms: If the label says "enzymes" or "rennet," it likely contains animal-derived rennet.
Look for Certifications: Look for a vegetarian society or kosher certification symbol on the packaging. These indicate that the cheese does not contain animal rennet.
Research the Brand: If you frequently buy a specific cheese, contact the manufacturer for clarification.
Authenticity Matters: Certain protected designation of origin (PDO) cheeses, especially from Europe, are legally mandated to use animal rennet.

A Note on Acid-Set Cheeses

Not all cheeses use rennet. Some, such as fresh cheeses, are coagulated using an acid like vinegar or lemon juice instead. These are naturally rennet-free and suitable for vegetarians.

Examples of acid-set cheeses include:

Ricotta
Paneer
Queso Fresco
Cream Cheese
Cottage Cheese

Conclusion

Identifying which cheeses have rennet involves knowing their origin, the rennet type used, and how to read food labels. Classic European cheeses like Parmigiano-Reggiano almost always use animal rennet, but many modern versions use vegetarian-friendly microbial or FPC rennet. Paying attention to labeling and certifications helps vegetarians and those with specific dietary needs make informed choices.

For more information, visit Wisconsin Cheese.

Frequently Asked Questions

No, not all cheese is made with rennet. Some cheeses, especially fresh varieties like ricotta, paneer, and some cottage cheeses, are set using acid instead of rennet.

Several cheeses with a Protected Designation of Origin (PDO), such as authentic Parmigiano-Reggiano, Gruyère, Grana Padano, and Pecorino Romano, often use animal rennet.

Microbial rennet is a vegetarian-friendly enzyme produced by fermenting specific fungi or molds. It is a common alternative to animal rennet in commercial and mass-produced cheeses.

To tell if a cheese is vegetarian, look for labels stating 'vegetarian rennet,' 'microbial enzymes,' or a vegetarian or kosher certification symbol. If the label is vague and lists only 'enzymes,' it likely contains animal rennet.

Yes, many aged cheeses can be vegetarian if they are made with a microbial or FPC rennet substitute. However, some believe animal rennet provides a more complex flavor for aged cheeses, so checking the label is crucial.

It can be, but it depends on the manufacturer. Many mass-produced cheddars use microbial rennet, but some artisanal cheddars still use animal rennet. Always check the ingredient list for clarification.

Rennet acts as a coagulating agent, causing milk proteins (casein) to clump, forming solid curds. This is essential for separating the solids from the liquid whey to create cheese.