The production of cheese requires the use of enzymes to coagulate or curdle the milk and the addition of other ingredients for various functions. The enzymes can be derived from animal, vegetable, or microbial sources. The animal sources include pigs and cattle. The enzyme derived from pigs is called pepsin and is haram. Another enzyme derived from pigs or small cattle is lipase. (Lipase can also be made by microorganisms, which is halal.) One of the enzymes derived from the inner lining of the fourth stomach of calves is called rennet. It may come from Zabiha calves or non-Zabiha calves. The enzyme can also be produced by microbial methods. Microbial enzymes are not derived from meat and are halal.
Rennet is a crude preparation containing dried, ground linings of the calf stomach. The active enzyme is called chymosin. Today, purified chymosin is also manufactured through genetic modifications of microorganisms when the chymosin gene from a calf is duplicated and inserted into microbial cells. Calf rennet is still used by specialty cheese manufacturers. Moreover, pig enzymes, such as lipase, are still used in high flavor, ripened cheeses, like romano.
Today, most cheeses in the North American markets are questionable. However, IFANCA has certified some specialty cheeses. Most cheese products do not list the source of the enzyme, so one must ask the producer from where the enzyme comes. Of course, it is possible the source will change without notification.
Finally, cheese products may contain many other ingredients, each of which must also be examined.
And ALLAH, Subhanahu wa ta’ala, knows best.