Can rennet used in hard cheese render the product non-kosher?

A product containing a minuscule amount of a non-kosher ingredient is often regarded as kosher, as the non-kosher substance is batel, or nullified. However, rennet used in hard cheese cannot be batel because of the halachic axiom that a non-kosher ingredient that gives a product its form—called a davar hama’amid—is never nullified (Yoreh Deah 87:11). Even trace amounts of such an ingredient can affect the kosher status of a product. Rennet is one of the most potent food enzymes, and it is therefore used in hard cheese in minute amounts; nevertheless, it cannot be batel.