Kosher cheese – Ask the Rabbi
Q. What makes cheese kosher? What can be non-kosher about ordinary cheese?
A. To get milk to curdle and turn into cheese, a small amount of a substance called rennet is added. This is extracted from the stomach of young calves.
Kosher cheese uses rennet taken from the stomach of animals slaughtered according to shechitah.
The Mishnah says that “if a person curdles milk with the skin of the stomach of an animal that was properly slaughtered and it imparts its flavour to the milk, it is forbidden” (Chullin 8:5); when rennet is used the quantity is too small to affect the flavour of the milk (Yoreh De’ah 87:11).
Alternatively, it is possible to use a completely vegetarian rennet.
There is a second objection to non-kosher cheese.
There is a rabbinic prohibition of “non-Jewish” cheese. This applies even when that the cheese contains only kosher ingredients.
Therefore, in order to be kosher, the cheese must have been made or its manufacture supervised by a religiously reliable Jewish person.
The supervisor ensures that the machinery is completely clean, that only kosher rennet is used and, preferably, that by means of a token payment s/he is the owner of the milk.
