Finding cheeses that subscribe to kosher dietary guidelines can be a challenge, both for casual and strict observers. The body of knowledge that surrounds the definition of "kosher" provides (unfortunately) a variety of ways that the term can be applied to cheese. I've tried to gather the pertinent information surrounding the topic so that you can judge for yourself which cheeses fall within your personal guidelines.
What is kosher?
Kosher foods are those foods that conform to Jewish dietary laws, or kashrut. Put simply (very simply) an animal that chews a cud and has a cloven hoof is kosher, while an animal that exhibits only one of the two traits is not kosher. The common milk-producing animals cow, sheep, and goat, are all considered kosher, so the milk from these animals would also be considered kosher.
Kosher observance prohibits consumption of dairy and meat during the same meal, and herein lies the debate about kosher observance and cheese. Many common cheeses - especially traditional European cheeses - are made with a substance derived from to stomach of a young animal. That substance is called “rennet.”
What is cheese?
Most cheeses follow the same four basic steps in their manufacture: acidifying the milk, coagulating the milk, draining the liquid (whey), then molding and aging the cheese. Some cheeses are made by combining the first two steps; acidifying (or souring) will cause the milk to separate into curds and whey that can be processed into cheese (acid-set cheese). These would include a number of fresh cheeses, like cream cheese, farmer’s cheese, some goat cheeses to name a few. Most formed cheeses, like brie, cheddar, swiss, etc., include a separate step of adding an enzymatic coagulant, known as rennet, to the milk.
What is rennet?
Rennet is the common term for an enzyme called chymosin. It is produced in the stomach lining of young ruminant animals (a ruminant is an animal that chews its cud). Medieval cheese-makers used dried strips of stomach lining from a young animal for coagulation, but modern science has developed a recombinant form of the enzyme called microbial rennet; there is also a vegetable source for the enzyme. Many American cheeses are made using the microbial form of the enzyme, while many Portuguese cheeses use the vegetable form.
What makes rennet non-kosher?
Since traditional rennet is derived from the stomach of an animal, one interpretation of kosher rules considers this basar bechalav: It violates the law proscribing the mixing of milk and meat. Strictly speaking, only cheese that is made without rennet (acid coagulation) or cheese made from non-animal rennet can be considered kosher (provided that the animal and the cheese-making process are also kosher). Although microbial rennet is produced by bacteria or fungi, the genetic engineering that created the microbes began by inserting the chymosin-producing genes from the animal form into a micro-organism. Today’s microbial rennet is self-replicating, but still uses that same genetic profile. Some dietary guidelines consider the recombinant form as being of animal origin, since the animal-derived enzyme is the foundation of the microbial form, but other guidelines consider the microbial form davar chadash – so far removed from the original source that it’s form could be consider kosher. To make things a bit more confusing, some schools of thought say that if the animal was ritually slaughtered under rabbinical supervision, then that rennet would be considered kosher.
How do I tell if a cheese is kosher?
The obvious first step is to find cheeses certified “kosher.” Then, depending on how you view the place of the rennet in the process, you would have to peruse the label to determine which type was used to make the cheese.
The majority of cheeses are labeled with their ingredients, which typically number four: Milk, bacterial cultures, rennet, and salt. The rennet ingredient can show up using a variety of terms, including rennet, traditional rennet, animal rennet, enzymes, microbial rennet, or vegetable/vegetarian rennet. Vegetarian rennet can be either microbial or vegetable derived, so the absolute non-animal source would say “vegetable rennet,” “vegetable enzymes” or sometimes “thistle rennet.”
Who makes kosher cheese?
Kosher markets will carry these cheeses, as well as local grocery stores (at least near the Jewish holidays). The website Kcheese.com offers a list of kosher cheese producers, many of which are available at cheese shops or grocers in major markets. A brief survey of that site shows a number of them specifically referencing ‘vegetable enzymes’ in their production.