Kosher cheeses are cheese products that follow the strict guidelines set by the kashrut, the set of traditional Jewish dietary laws. This entails that the animal from which the milk was taken to make the cheese must fit certain criteria described in the Torah, Jewish scripture. In some traditions, cheese can only be considered kosher if made by or under the supervision of a Jew knowledgeable in kosher production methods. In following orthodox Jewish tradition, eating kosher cheeses is also subject to certain guidelines. Popular cheeses considered kosher include cheddar, mozzarella, and Swiss cheese.
Jewish tradition dictates that kosher cheeses can only be made from animals that chew their own cud and possess cloven hooves. Since the majority of popular cheeses are made from animals that meet these requirements — cows, goats and sheep —, this rule is often overlooked. Kashrut demands, however, that animals must be free from disease in order to be considered kosher, rendering any cheese made from the milk of diseased animals treif, or not kosher. The topic of treif milk being mixed with kosher milk in large-scale dairy producers has been subject to debate, but most experts allow some leeway in the use of this milk.
The production of kosher cheeses is largely affected by the use of rennet, the enzyme that aids in the separation of milk curds from whey. Rennet is most commonly extracted from animal stomach linings, which makes cheese production open to incorporating non-kosher sources. Cheeses must be made with rennet from kosher animals, vegetables, or from microbial sources in order to be considered kosher. In addition, animal-based rennet can only be considered kosher if the source animals were slaughtered according to shechita, the traditional Jewish method of ritualistic slaughtering. In this regard, it is a commonly-accepted practice to have orthodox Jews present during cheese production to ensure the standards of kashrut are upheld; some branches of orthodox Judaism, particularly among Haredi Jews, go so far as to require it.
The consumption of kosher cheeses is also subject to certain laws. The primary consideration involves the prohibition of mixing meat with dairy. Due to this guideline, cheeses mixed with meat or meat products cannot be considered kosher. Although rennet can be obtained from animal sources, the enzyme does not qualify as meat and can, therefore, be used to make kosher cheeses. Some households follow this practice to a strict degree, often waiting for one to several hours in between eating meat and cheese, and using separate sets of dishes and utensils for meat and dairy foods.