Does Cheese Have Pig Enzymes? Exploring Rennet and Other Coagulants

November 11, 2025 •

4 min read

Over 90% of global cheese production uses a non-animal enzyme known as fermentation-produced chymosin, a fact that surprises many. This reality addresses the common question: does cheese have pig enzymes, or other animal-derived coagulants, and how can consumers know for sure?

Quick Summary

The inclusion of animal-derived enzymes in cheese, such as traditional rennet from ruminants or historical porcine pepsin, is dependent on the manufacturing process. Modern cheese often uses vegetarian or microbial enzymes, but consumers concerned about animal products must check labels, as some specialty cheeses may still use them.

Key Points

Rennet is an enzyme used to curdle milk in cheesemaking. Traditionally, it was sourced from the stomach lining of young ruminant animals like calves.
Porcine (pig) enzymes, particularly pepsin, were once widely used but have been mostly replaced. The use of porcine pepsin was heavy from 1960-1985 in the US but has declined due to modern alternatives.
Some specialty cheeses, like Romano, may still use porcine lipase. This is for specific flavor development, but it's not a common practice in mainstream production.
Microbial rennet and Fermentation-Produced Chymosin (FPC) are the most common modern alternatives. FPC, made by genetically engineered microbes, accounts for over 90% of global rennet use and is suitable for vegetarians.
Labeling can be vague, so look for certifications or specific terms. Look for "microbial rennet" or "vegetarian rennet". Kosher and Halal certified cheeses will not contain porcine enzymes.
Some soft cheeses and vegan alternatives do not use rennet at all. Acid-set cheeses like ricotta and paneer are rennet-free, as are most vegan cheeses.
Brands like Tillamook and Cabot are known for using microbial rennet. Checking a brand's website is a reliable way to verify their rennet source for specific products.

What is Rennet and Why is it Used in Cheesemaking?

Rennet is a complex of enzymes that plays a critical role in cheesemaking by causing milk to coagulate, or curdle, separating the milk solids (curds) from the liquid (whey). This process is the foundational step in creating almost all types of cheese. The primary active enzyme in rennet is chymosin, which acts on the milk protein casein, causing it to clump together. Historically, rennet was obtained exclusively from the stomach linings of young, milk-fed mammals, such as calves, lambs, and goats. However, increasing demand and the rise of vegetarianism have led to the widespread adoption of alternatives.

The Historical and Present Use of Pig Enzymes

While rennet is most famously derived from calves, enzymes from other animals have been used throughout history. Porcine pepsin, an enzyme found in the stomachs of pigs, was heavily utilized in cheese manufacturing in the United States, particularly between the mid-1960s and mid-1980s. However, its use has since declined significantly and has been largely replaced by more consistent and cost-effective alternatives, namely microbial enzymes and fermentation-produced chymosin.

Despite this shift, porcine enzymes are not entirely absent from the modern cheese landscape. A different pig-derived enzyme, porcine lipase, is still occasionally used in the production of some high-flavor, ripened cheeses, like Romano. This enzyme adds a specific taste profile that some cheesemakers desire. The crucial takeaway is that while the use of pig enzymes is not as common as it once was, it has not been completely eradicated and can be present in specific products.

Modern Rennet Alternatives

To meet consumer demand for vegetarian and ethically-sourced products, cheesemakers have developed and adopted several alternatives to animal rennet:

Microbial Rennet: Produced by fermenting specific fungi, such as Rhizomucor miehei, this type of rennet provides an effective and animal-free coagulant. It is a very common choice for many commercial cheeses, especially soft and young varieties, and is suitable for vegetarians.
Fermentation-Produced Chymosin (FPC): This is the most prevalent rennet substitute in the modern cheese industry, accounting for over 90% of global use. It is created by inserting the gene for calf chymosin into microorganisms like yeast or fungi, which then produce the enzyme through fermentation. The resulting chymosin is identical to the one from calves but is a highly purified, animal-free product.
Plant-Based Rennet: Derived from plants like cardoon thistle, fig leaves, or nettles, this type is used in some traditional and artisanal cheeses, particularly from the Mediterranean. However, it can sometimes introduce a slightly bitter taste and offers less consistent results than other types, making it less common for mass production.

How to Identify Cheeses Without Animal Enzymes

Navigating the cheese aisle can be confusing, but a few key steps can help consumers avoid animal-based enzymes:

Check the label: Search for specific terms like "vegetarian rennet," "microbial rennet," or "non-animal enzymes" on the ingredients list. If the label only lists "enzymes" without further specification, it is more likely to contain animal-derived rennet.
Look for certifications: Products with Halal or Kosher certifications are guaranteed to be free of pig enzymes. Kosher certification prohibits the mixing of meat and dairy, ensuring no porcine products are used. A Halal label confirms that any animal-derived ingredients meet Islamic dietary laws.
Choose traditionally acid-coagulated cheeses: Some cheeses do not use rennet at all. These are often fresh, soft cheeses that are curdled using an acid like vinegar or lemon juice. Examples include ricotta, paneer, and some cream cheeses.
Research specific brands: Many large commercial brands openly state their use of non-animal rennet. A quick search on the company's website or an inquiry with customer relations can provide clarity. For instance, Tillamook and Cabot are noted for using microbial rennet in many of their cheeses.

Comparison of Rennet Types


Feature	Animal Rennet	Microbial Rennet	Fermentation-Produced Chymosin (FPC)	Plant-Based Rennet
Source	Stomach of young ruminants (calves, lambs)	Specific fungi and molds	Genetically engineered bacteria or yeast	Plants like thistles, figs, nettles
Common Use	Traditional, long-aged cheeses (e.g., Parmigiano-Reggiano, some Cheddars)	Many commercial, mass-produced cheeses	Widely used in the modern cheese industry	Some artisanal and specialty cheeses
Vegetarian-Friendly	No	Yes	Yes	Yes
Flavor Impact	Valued for traditional flavor profiles	Improved quality, less bitter over time	Produces a clean flavor profile	Can impart a slightly bitter taste
Consistency	Can vary depending on source	Consistent for large-scale production	High consistency and purity	Can be inconsistent

The Final Verdict for Your Nutrition Diet

For those adhering to specific dietary or ethical guidelines, the source of cheese-making enzymes is a significant consideration. While the use of porcine enzymes, particularly pepsin, is a historical practice that has largely ceased, specific pig enzymes like lipase still find their way into some specialty products. Fortunately, the rise of microbial and FPC rennet has made it easier to find high-quality, animal-free cheese options. A combination of careful label-reading, looking for specific certifications, and choosing certain types of cheese is the best strategy for a nutrition diet that avoids animal-derived enzymes. The good news is that the market offers plenty of delicious choices that are transparent about their ingredients, empowering consumers to make informed decisions.

Conclusion

The question of whether cheese contains pig enzymes is complex, with the answer depending on the specific product and manufacturer. While the widespread use of porcine enzymes is a relic of the past, they are not entirely extinct in the cheese industry. Modern advancements, driven by consumer demand, have introduced numerous vegetarian-friendly alternatives to animal rennet. By understanding the different types of coagulants and practicing diligent label-reading, consumers can confidently navigate the cheese market and find products that align with their dietary needs and preferences. The availability of microbial and plant-based options means that delicious cheese can be part of many different diets, regardless of their stance on animal enzymes.

Frequently Asked Questions

No, not all cheese is made with animal rennet. Many modern cheeses, especially mass-produced varieties, use microbial rennet or fermentation-produced chymosin (FPC) instead. Some soft cheeses also use acid-based coagulation instead of rennet.

To determine if a cheese is made with pig enzymes, you must carefully read the label. Look for specific labels like 'microbial rennet' or 'vegetarian rennet.' If the ingredients list simply says 'enzymes' or 'rennet,' it might be animal-derived. Choosing products with Kosher or Halal certification is the most reliable way to ensure no porcine enzymes are used.

Yes, kosher-certified cheeses are guaranteed not to contain any pig enzymes. According to kosher dietary laws, meat and dairy products cannot be mixed, which precludes the use of any animal-derived rennet or enzymes in cheese-making.

Many traditional European cheeses, particularly hard and aged varieties like authentic Parmigiano-Reggiano, Pecorino Romano, and some artisanal cheddars, are known to use animal rennet. For these cheeses, you should always check the label or consult with a cheesemonger.

Microbial rennet is an enzyme extracted directly from fermented fungi. FPC, or Fermentation-Produced Chymosin, is created using genetically modified microorganisms that produce a very pure, highly consistent version of the chymosin enzyme, making it the most common rennet substitute worldwide.

Soft cheeses that rely on acid coagulation rather than rennet are naturally rennet-free. These include fresh cheeses like ricotta, paneer, and cottage cheese, as well as some types of cream cheese.

Yes, if a product is labeled with "vegetarian rennet," it means the coagulating enzyme used is not from an animal source. This can be either microbial or plant-based, making the cheese suitable for vegetarians.