A Traditional Practice in a Modern World
Rennet is a complex of enzymes used to coagulate milk, separating it into solid curds and liquid whey. For centuries, cheesemakers have sourced these enzymes from the stomachs of young mammals. While calf rennet has been the most common animal source, the use of pig rennet is a highly specific and nearly obsolete practice today. The modern food industry has largely shifted towards more widely available and consistent alternatives, including microbial, plant-based, and fermentation-produced rennet. For consumers, this shift means that the vast majority of cheeses on store shelves do not contain pig-derived enzymes.
The Standout: Pecorino di Farindola
The most prominent and well-documented example of a cheese made with pig rennet is the traditional Pecorino di Farindola. This unique ewe's milk cheese originates from the Abruzzo region of Italy. What makes its production so special is that it is made with rennet extracted from the stomach of a pig, a practice with roots stretching back over 2,000 years.
Key Characteristics of Pecorino di Farindola:
- Produced exclusively by a small cooperative in the mountainous Farindola area.
- Rennet is sourced directly from locally-raised pigs, rather than being industrially produced.
- Research has shown that the use of pig rennet gives the cheese a distinctly different flavor profile compared to versions made with calf rennet, with the pig-rennet cheese being notably sweeter and less bitter.
- It is a protected Slow Food Presidium product, safeguarding its traditional production method.
The Role of Porcine Enzymes vs. Pig Rennet
It is important to distinguish between pig rennet (containing chymosin) and other porcine enzymes, such as lipase, which are sometimes used in cheese making. While true pig rennet is exceptionally rare, porcine lipase is occasionally employed to develop specific flavors. The Islamic Food and Nutrition Council of America (IFANCA) notes that porcine lipase is sometimes used in high-flavor, ripened cheeses like Romano to enhance flavor, but this is a different enzymatic process than initial coagulation. When checking cheese ingredients, this distinction can be important, as different enzymes serve different functions in the aging and flavor development process.
Other Traditional Animal Rennets
While pig rennet is a niche product, other animal rennets are still used in many traditional European cheeses, especially those with protected designation of origin (PDO) status. These traditionally use enzymes from ruminants. For example, some cheeses that have historically used animal rennet from calves or lambs include:
- Parmigiano-Reggiano (calf rennet)
- Grana Padano (calf rennet)
- Manchego (lamb rennet)
- Pecorino Romano (lamb rennet)
These are distinct from pig rennet, and the specific animal source is often part of the traditional recipe required for a PDO certification.
Comparison of Rennet Types
| Rennet Type | Source | Common Application | Vegetarian/Dietary Status |
|---|---|---|---|
| Pig Rennet | Stomach lining of young pigs | Pecorino di Farindola | Not Vegetarian, Halal Issues |
| Calf Rennet | Stomach lining of young calves | Traditional hard cheeses (Parmigiano-Reggiano) | Not Vegetarian, Halal Issues |
| Microbial Rennet | Fungi (e.g., Rhizomucor miehei) | Many mass-produced cheeses | Vegetarian, Kosher, Halal |
| FPC Rennet | Genetically engineered microbes | Large-scale cheese production | Vegetarian, Kosher, Halal |
| Vegetable Rennet | Plants (e.g., cardoon thistle, fig leaves) | Some artisanal and fresh cheeses | Vegetarian |
Labeling and Consumer Awareness
For consumers, especially those with dietary restrictions related to pork, understanding rennet sourcing is crucial. Unfortunately, regulations do not always require the specific animal source to be listed. Labels may simply state “enzymes,” “animal enzymes,” or “rennet”. This ambiguity means that the only way to be certain is to look for specific vegetarian or kosher certifications, or to contact the manufacturer directly. However, given the extreme rarity of pig rennet in commercial production, the risk is very low outside of specific, artisanal cheeses.
Conclusion
The question of which cheeses use pig rennet leads to a surprising and specific answer: very few, with the most famous example being the traditional Italian Pecorino di Farindola. This is a unique, historic case, not a common practice in the modern cheese industry. While some cheeses might contain other porcine enzymes like lipase for flavor, the coagulation process itself is overwhelmingly reliant on calf rennet or, more commonly today, microbial and FPC alternatives. For those concerned about dietary restrictions, the best approach is to seek out products explicitly labeled as vegetarian or certified kosher, as general “enzymes” labels do not offer specific guarantees. The rarity of pig rennet use in cheese production today highlights the evolution of modern food manufacturing away from some of its most ancient and specific techniques. For a deeper dive into the rarity of Pecorino di Farindola, see this article by Culture Cheese Magazine.
