Understanding the role of rennet in cheesemaking
Rennet is a crucial component in the production of most cheeses. It is a complex mixture of enzymes that causes milk to coagulate, separating the liquid whey from the solid curds that will eventually be pressed into cheese. The primary active enzyme in rennet is chymosin, which is responsible for this coagulation.
Historically, and still today for many traditional cheeses, rennet is sourced from the stomach lining of young, unweaned ruminant animals like calves, lambs, and goat kids. However, the dairy industry now widely uses several alternatives to animal-derived rennet, including microbial, vegetable, and fermentation-produced chymosin (FPC). The choice of rennet significantly influences the final flavor, texture, and aging process of the cheese.
The unique case of Pecorino di Farindola
In the mountainous Abruzzo region of Italy, a truly exceptional cheese breaks from the norm. Pecorino di Farindola is a sheep's milk cheese and is believed to be the only one in Italy, and possibly the world, made with pig rennet. This long-standing tradition dates back over 2,000 years to the ancient Vestini tribe who inhabited the region.
Unlike commercially available animal rennet, the pig rennet for Pecorino di Farindola is not an industrial product. It is traditionally made by the local producers themselves from the stomachs of pigs they raise. The rennet is created through a meticulous, labor-intensive process that can involve infusing the stomach lining in local white wine for several months or even over a year. The techniques are often passed down from mother to daughter, earning it the nickname "pecorino delle donne" (women's cheese).
How pig rennet affects the flavor profile
The use of pig rennet is not just a historical custom; it directly contributes to the cheese's unique characteristics. A 2013 study compared Pecorino di Farindola made with pig rennet to an ewe cheese made with calf rennet under similar conditions. The results showed a significant difference in taste, with the pig rennet cheese consistently described as sweeter and never bitter, in contrast to the spicier and sometimes bitter flavor of the calf rennet cheese. This is likely due to the different enzyme profiles present in porcine rennet compared to ruminant rennet.
Beyond Pecorino: The wider world of rennet in cheese
For those who adhere to specific dietary rules, such as vegetarian, kosher, or halal diets, it's essential to understand that pig rennet is just one of many types of coagulants. Most commercially produced cheeses today do not use animal rennet at all, with fermentation-produced chymosin (FPC) holding a significant share of the market.
Comparing different types of rennet
| Type of Rennet | Source | Common Uses | Dietary Suitability | Flavor Impact |
|---|---|---|---|---|
| Porcine Rennet | Pig stomach lining | Pecorino di Farindola | Not Vegetarian, Kosher, or Halal | Contributes a distinctive, often sweet and non-bitter flavor. |
| Calf Rennet | Calf stomach lining | Traditional hard cheeses like Parmigiano Reggiano | Not Vegetarian | Often provides a classic, robust flavor profile prized in aged cheeses. |
| Microbial Rennet | Certain molds/fungi | Soft cheeses, many mass-produced hard cheeses | Vegetarian | Can sometimes introduce a slightly bitter note to cheeses that are aged for a long time. |
| Vegetable Rennet | Plants (thistle, fig) | Artisanal, traditional Mediterranean cheeses | Vegetarian | Variable strength and can contribute a bitter flavor, especially with age. |
| FPC (Fermentation-Produced Chymosin) | Genetically modified microbes | Most major commercial cheese brands | Vegetarian (also Kosher/Halal certified) | Highly consistent, pure chymosin that produces predictable results without flavor variations. |
How to tell what rennet was used
Because food labeling laws differ, it can be difficult to determine the source of rennet in a product simply by reading the ingredients list. In many places, manufacturers are not required to specify the type of rennet used. However, there are clues to look for:
- Labeling: Products specifically marketed as "vegetarian cheese" or carrying kosher or halal certification symbols will not contain pig rennet or other animal-derived coagulants. Conversely, some traditional European cheeses, particularly those with a Protected Designation of Origin (PDO), must use traditional animal rennet.
- Brand Information: Some cheese companies, especially those producing vegetarian options, will explicitly state "vegetarian rennet," "microbial enzymes," or "fermentation-produced chymosin" on their packaging or website.
- Manufacturer Inquiry: For products with vague labeling, contacting the manufacturer directly is the most reliable method for determining the source of their enzymes.
The wider nutritional and dietary implications
Choosing cheese based on its rennet source has more to do with dietary and ethical considerations than nutrition. The final nutritional content of cheese is largely determined by the type of milk, aging process, and moisture content, not the coagulant. Therefore, consumers choose rennet-specific cheeses for various reasons:
- Vegetarians: Individuals following a vegetarian diet will avoid cheeses made with animal rennet, opting for microbial or vegetable alternatives instead.
- Kosher/Halal Consumers: Observant individuals adhering to kashrut or halal laws will need to ensure not only that the rennet is not from a forbidden animal (like a pig) but also that it comes from a properly slaughtered animal or a non-animal source. FPC is often used for these certifications.
- Culinary Enthusiasts: Those seeking a specific flavor and texture, particularly in certain aged cheeses, may prefer products made with traditional animal rennet, including the unique notes imparted by porcine rennet in Pecorino di Farindola.
Conclusion: Navigating the world of cheese and rennet
While Pecorino di Farindola is a rare and distinct example of a cheese that uses pig rennet, it is not the norm. The vast majority of cheeses available today are made with calf rennet, or more commonly, microbial or fermentation-produced chymosin. For most cheese lovers, the type of rennet used might seem like a minor detail, but for those with specific dietary requirements or culinary preferences, it's a vital piece of information. Understanding the different sources of rennet empowers consumers to make informed choices that align with their ethical and gastronomic values. When in doubt, checking for explicit labeling or contacting the producer is the most reliable way to know what you're eating.
Explore the world of cheese with confidence by understanding its key ingredients.
