Say Kosher Cheese Title Image

By: Judy Pister

There is a distinct prohibition on eating cheese made by a non Jewish person, termed gevinat akum, even if the ingredients and equipment are in fact kosher. This strictly adhered to halacha is derived from the Talmud which states that it is forbidden to eat cheese manufactured by a non-Jewish person. One of the reasons for this enactment is due to the use of an ingredient called rennet which enables milk to coagulate and set. Historically, rennet was derived from the lining of a calf’s stomach, which could violate laws prohibiting the mixing of milk and meat. Today, almost all kosher cheese manufacturers and even some non kosher ones use microbial rennet, whereby the rennet is produced by growing it on microorganisms. Nevertheless, the law of gevinat akum remains in effect and, therefore, an observant Jewish person must supervise and participate in the production.

What does a kosher cheese production run entail?

Kosher Ingredients

The first step is to ensure that the rennet (irregardless of its source), the starter, and any additives are certified kosher.

Gevinat Akum

In order to avoid the issue of gevinat akum, a mashgiach must be present during the entire cheese run process. There are several cheese producers that manufacture kosher cheese and therefore, abide by the rules that COR (as well as all mainstream kosher certifiers) enforce. These cheese runs are scheduled weeks in advance so that the company can book the time and COR can make the necessary travel arrangements, usually to the east coast, for a mashgiach to be present.

Kosher Run

A kosher run must be completely segregated from non kosher. Before the run starts, allequipment must be spotlessly clean, attention is paid to residual caseins on walls of vats, and residual cheese on cutting wires, knives, hoops, etc. A decision must be made whether a full kashering of the equipment is necessary. If the temperature of the non-kosher cheese does not exceed 113° F (45° C), or the degree of heat is such that the hand recoils when it touches it (yad soledet bo) then a meticulous cleaning is sufficient. If non kosher cheese is produced at temperatures above 45° C an intense “kosherizing” of the equipment is necessary. Based on the length of time required for the kosher run, it may be necessary to have two mashgichim working back to back.

Why does a Mashgiach have to add the rennet?

Once the equipment is ready, the process starts with the mashgiach adding the bacterial culture or starter to the vat. Further into the process, the mashgiach adds the rennet in order for coagulation to occur. By having a Jew perform these two crucial tasks, the cheese receives the designation gevinat yisroel and is therefore, granted kosher certification. This designation applies to all hard cheese, where rennet is used.


When the cheese blocks are made, the lot numbers are recorded and the blocks are labeled with special production stickers. Careful recording procedures ensure proper documentation. Once the information is forwarded to the COR, a special letter of certification is issued for the run.

The kosher cheese will require an exclusive name and label design. It must be different enough so as to prevent any possible association by the consumer of the kosher and non-kosher products.

Further Processing

It is possible that this kosher cheese is then sent to another facility for shredding. Once again, a mashgiach must ensure that the equipment is clean and that the cheese block is from a kosher run before permitting the shredding process and packaging process. Here again, the mashgiach, termed a mashgiach temidi (or constant supervisor), must be present for the entire production.

How is kosher cheese production different in preparation for Passover?

The first step is to ensure that the ingredients are permissible for Passover. Often the creation of the bacterial starter cultures and enzymes used for cheese production are fermented in environments and surfaces which are not acceptable for Passover production. Some starters are even grown on bread! It is unlikely matzah could provide a viable alternative. Vinegar is sometimes added to cheese vats in order to balance pH levels. If this is the case, kosher for Passover vinegar must be used. If any flavourings are added to the cheese, they too must be carefully checked to ensure that they are certified for Passover use.

All equipment and utensils used for the cheese production must be thoroughly cleaned and washed in scalding water under the supervision of the mashgiach.

So, the next time you are eating COR certified cheese, remember that the cheese production has been through a meticulously planned, monitored and executed process to receive its kosher designation!