The Core Issue: Understanding Animal Rennet
At the heart of the matter for vegetarians is the use of animal rennet. Rennet is a complex set of enzymes, primarily chymosin, that causes milk to coagulate and separate into solid curds and liquid whey. For thousands of years, cheesemakers have sourced this enzyme from the inner mucosa of the fourth stomach chamber of unweaned animals, typically calves, lambs, and goats. This process requires the animal to be slaughtered, making any cheese produced with this ingredient unsuitable for strict vegetarians.
The Traditional Production of Animal Rennet
The traditional method involves processing the dried and cleaned stomachs of young animals. These are typically a byproduct of the veal industry.
- The stomach lining is first dried and cleaned.
- It is then cut into small pieces and soaked in a brine solution, often with added vinegar or wine to lower the pH.
- After a period of soaking, the resulting liquid is filtered and used to curdle milk.
- The modern industrial method uses deep-frozen stomachs, which are milled and purified to produce a more potent and consistent rennet extract.
The Rise of Vegetarian-Friendly Alternatives
As the vegetarian and ethical food movement has grown, so too has the demand for alternatives to animal rennet. Thankfully, cheesemakers have developed several viable options.
Microbial Rennet
This is the most common alternative, used in the vast majority of commercial cheeses today.
- It is derived from the fermentation of specific fungi or molds, such as Rhizomucor miehei.
- Using modern biotechnology, some versions known as fermentation-produced chymosin (FPC) are made by inserting the animal gene for chymosin into a microorganism like yeast. The resulting enzyme is identical to animal chymosin but is entirely free of animal products.
Plant-Based Rennet
Certain plants naturally produce enzymes that can also coagulate milk. This method has been used for centuries, particularly in certain Mediterranean cheeses.
- Common plant sources include cardoon thistle, artichokes, and fig tree sap.
- Plant rennets can sometimes impart a distinct flavor or result in a different texture, making them suitable for specific artisanal cheeses but less common for mass production.
Acid Coagulation
Some fresh cheeses don't rely on rennet at all. Instead, milk is coagulated by adding an acid like vinegar, lemon juice, or citric acid. This method is suitable for certain soft cheese varieties.
How to Identify Vegetarian Cheese
Finding vegetarian-friendly cheese requires diligent label reading and an understanding of specific product regulations. Manufacturers are required to list the type of coagulant used, but the terminology can vary.
Common Labeling Terms:
- Vegetarian Rennet: A clear indicator that the cheese is suitable for vegetarians.
- Microbial Enzymes: Refers to rennet derived from molds or fungi.
- Plant-Based Enzymes: Identifies rennet sourced from plants.
- Enzymes: This generic term can be ambiguous. It could be either animal or microbial. If the label only says "enzymes," it is best to assume it is not vegetarian unless stated otherwise.
- Not Vegetarian: Traditional artisan or protected designation of origin (PDO) cheeses, like Parmigiano Reggiano and some Gruyère, are legally required to use animal rennet. Always research these specialty varieties.
A Comparison of Rennet Types
| Feature | Animal Rennet | Microbial Rennet | Plant-Based Rennet |
|---|---|---|---|
| Source | Stomach lining of young ruminants (calves, lambs) | Fermentation of specific fungi or genetically modified microbes | Extracts from plants like thistle or fig sap |
| Availability | Limited supply, often a byproduct of the meat industry | Wide availability, cost-effective, unlimited supply | Less common for mass production, often used by artisanal makers |
| Taste Impact | Traditionally believed to offer the best, cleanest flavor, especially for aged cheeses | Can sometimes produce bitter off-flavors, especially in aged cheeses, though this has improved | Can impart specific, and sometimes bitter, flavors from the plant source |
| Vegetarian-Friendly | No | Yes | Yes |
| Common Usage | Required for certain traditional, Protected Designation of Origin (PDO) cheeses | Dominates modern, large-scale commercial cheese production | Used mainly in specific artisanal or regional cheeses |
The Evolution of Cheesemaking
The historical reliance on animal rennet was simply due to its discovery and effectiveness. Legend even suggests the first cheese was made by accident when a nomad stored milk in a pouch made from an animal's stomach. As the global food system evolved, the limitations of animal rennet became apparent, prompting the search for alternatives due to cost, supply, and ethical concerns. The development of microbial and fermentation-produced chymosin in the 20th century was a major turning point, allowing for mass production of consistent, vegetarian-friendly cheeses.
Conclusion: Choosing Cheese with Confidence
For a vegetarian, the question "why is cheese not vegetarian?" is a crucial one that highlights a key aspect of food production. While it's true that traditional cheesemaking practices exclude many products from a vegetarian diet, modern alternatives are now the standard for most commercially available cheeses. By checking labels for terms like "microbial enzymes" or "vegetarian rennet," vegetarians can confidently select products that align with their dietary principles. For specialty or imported cheeses, always confirm the specific production methods, as some traditional cheeses are still bound by regulations to use animal-based rennet. The modern food landscape offers a wide variety of options, making it easier than ever to be a vegetarian cheese lover.
