Which Cheeses Contain Rennet?
When you pick up a wheel of cheese, you may not realize that an enzyme called rennet is often part of how that cheese was made. That detail becomes crucial if you follow a vegetarian, kosher, halal, or allergen-sensitive diet.
Below you'll find how rennet works, its different types, and examples of cheeses that typically use it (versus those that don't).
What is rennet, and why is it used?
Rennet is a set of enzymes whose primary function is to coagulate milk, separating it into curds (solid) and whey (liquid). The main active enzyme is chymosin, often supported by pepsin and lipase.
- Historically, rennet came from the stomach lining of ruminant mammals (especially calves). That is why many traditional cheeses are not considered vegetarian or suitable for certain dietary restrictions.
- Over time, alternatives emerged: microbial rennet (from fungi or bacteria), plant-based rennet (from thistle, nettles, fig leaves), and fermentation-produced chymosin (FPC), where microbes are engineered to produce the same enzyme.
- Today, in some regions, most cheese is produced using non-animal rennet (especially in mass commercial dairies). For example, in the U.S., less than 5 percent of cheese uses traditional animal rennet now.
Still, many heritage or Protected Designation (PDO) cheeses must use animal rennet because of tradition or regulation.
Types of rennet (and implications)
| Type | Source / Method | Pros / Cons | Notes |
|---|---|---|---|
| Animal rennet | Stomach lining (typically from calves) | Very effective, clean flavor, reliable yield | Many traditional European cheeses require this. |
| Microbial rennet | Fungi or bacteria naturally producing coagulating enzymes | Vegetarian, no animal tissue; possible bitter notes in some aged cheeses | Widely used as substitute. |
| Plant-based rennet | Enzymes from plants (thistle, nettles, fig, etc.) | Vegetarian, natural, but yield or consistency may vary | Traditional in some Mediterranean cheeses. |
| Fermentation-produced chymosin (FPC) | Microbes genetically engineered to produce the same enzyme | Economical, consistent, non-animal tissue, widely accepted | Many large producers use this now. |
Because the term "vegetarian rennet" is not strictly regulated, cheese producers sometimes use microbial or FPC rennet but label it vaguely as "enzymes."
Which cheeses almost always use rennet?
Many hard, aged, or traditional cheeses depend on rennet to form a firm structure and develop richness over time:
- Parmesan / Parmigiano-Reggiano: traditional versions must use animal rennet under PDO regulation.
- Pecorino Romano: typically made with animal rennet.
- Manchego: often use animal rennet in traditional recipes.
- Gruyère, Emmental, Gouda, Cheddar, Swiss: many of these traditionally use animal rennet.
- Stichelton (a blue cheese made in England) uses raw milk and calf-derived rennet.
- Berkswell (a hard ewe's milk British cheese) uses animal rennet.
Some widely sold cheeses have shifted to microbial or FPC rennet, making them suitable for vegetarians, especially in regions where consumer demand is high.
Cheeses that often avoid rennet (or use acid coagulation)
Several fresh or soft cheeses coagulate by acid, not by enzyme, meaning they may be safe for vegetarians (depending on ingredients).
Examples:
- Paneer (Indian fresh cheese) is made by adding an acid like lemon juice or vinegar rather than rennet.
- Queso fresco, ricotta (in many traditional forms), cream cheese: often use acid or culture rather than rennet.
- Some artisan cheeses marketed as "vegetarian cheese" use plant or microbial rennet instead of animal.
- Coquetdale (English semi-hard) is made with vegetarian rennet.
- Tintern, a Welsh blended cheddar herb cheese, uses vegetarian rennet in its formulation.
Still, one must check the labeling. Some cheeses may list "enzymes" without clarifying what kind.
How to know (or verify) what you are eating?
- Look for terms like microbial rennet, vegetarian rennet, and fermentation-produced chymosin on the label.
- Be cautious with vague "enzymes" or "coagulants" - these may hide animal rennet.
- In specialty shops, ask cheesemakers directly about their process.
- For PDO cheeses (like Parmigiano-Reggiano), the rules often require animal rennet.
- Some retailers now label cheeses by the rennet type, especially for vegetarian or kosher compliance.
Below is a table with two columns:
- cheeses that traditionally contain animal rennet,
- cheeses that are typically made without rennet (or with acid or non-rennet coagulation).
Some cheeses in column 2 may occasionally be made with rennet depending on the producer, so always check labels.
| Cheeses that traditionally uses animal rennet | Cheeses that are typically made without rennet (or using acid, or non-rennet coagulation) |
|---|---|
| Parmigiano-Reggiano / Parmesan | Paneer (Indian fresh cheese) |
| Pecorino Romano | Ricotta (fresh versions) |
| Grana Padano | Cream cheese |
| Gorgonzola (traditional) | Cottage cheese |
| Manchego (traditional) | Mascarpone |
| Gruyère | Fromage blanc / fromage frais |
| Emmental / Swiss | Queso fresco (fresh) |
| Cheddar (traditional) | Labneh (strained yogurt cheese) |
| Edam / Gouda (traditional) | Fresh farmer's cheese/curds |
| Provolone (traditional) | Cottage curds (unacidified) |
| Asiago (when made traditionally) | Some fresh goat cheeses (if acid-set) |
| Roquefort (traditional) | Some Greek style soft cheeses (unaged) |
| Comté | Some versions of chèvre (fresh goat cheese) |
| Fontina (traditional) | Whey cheeses (when made from leftover whey) |
| Emmental (traditional Swiss) | Acid curd cheeses generally |
| Munster (when traditional) | Some versions of fresh cheeses like labneh, etc. |
| Mozzarella (traditional / aged) | Nieheimer (a German sour-milk cheese made without rennet) |
| Asiago (aged) | - (fresh non-rennet cheeses overlap) |
| Fontina (aged) | - |
| Comté (aged) | - |
| Roquefort (PDO) | - |
Notes/caveats:
- Many soft, fresh cheeses are acid-coagulated (using lemon juice, vinegar, or cultures), and thus avoid the need for rennet.
- In modern production, even many cheeses listed in the "animal rennet" column are sometimes made with microbial or vegetarian rennet instead, so "traditionally using animal rennet" doesn't guarantee every version uses it.
- PDO (Protected Designation of Origin) cheeses in Europe often require use of animal rennet under their specification (for example, Parmigiano-Reggiano, Pecorino Romano)
- The presence of "enzymes" or "coagulants" in an ingredient list can mask the actual type of rennet used, so always verify if the packaging explicitly states microbial, vegetable, or animal rennet.
And you can always ask the seller about how the particular cheese product is made to make sure you pick the best one.
Closing note
Rennet plays a behind-the-scenes role in cheese production, but one with meaningful dietary and ethical implications.
Many traditional cheeses rely on animal rennet, while modern options (microbial, plant, or fermentation chymosin) offer flexibility and broader consumer acceptance.
Again, if your diet or values require avoiding animal rennet, always check labels or source from trusted producers who disclose their method.
