Is Parmesan Cheese Vegetarian?
True Parmigiano-Reggiano cheese is made with something called rennet. Rennet comes from the lining of a calf’s fourth stomach, according to Formaggio Kitchen. It contains enzymes called chymosin and pepsin, which coagulate the proteins in milk so it forms curds. Coagulation is the denaturing (or unfolding), of the protein molecules so they form structures that hold water, per ACS Publications. Young calves are used because the concentration of these enzymes decreases in the stomach lining as the animal is weaned, via the Association of Manufacturers & Formulations of Enzyme Products.
The calves are killed for their meat (veal), and the stomach is a by-product of that slaughter, per MasterClass. The stomach is cut up and the rennet is extracted by soaking it in salt water, according to ChefSteps. This mixture is added to the milk and heated, which activates the enzymes. The curds are separated from the whey, then drained and pressed, and aged to form Parmesan cheese.
Therefore, true Parmesan cheese is not vegetarian. But all is not lost! There are some Parmesan products that are acceptable to vegetarians.
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