Vegetarians across the country may know how much it hurts to be turned down Parmesan cheese, otherwise known as Parmigiano-Reggiano, at restaurants.

This hard Italian cheese is a vegetarian product, unlike the vast majority of world cheeses.

But how can a cheese not be vegetarian?

Parmesan, which takes its name from the three places where it is made (Parma, Reggio Emilia and Bologna), is not vegetarian because its production involves animals.

The coagulation process, needed to make milk, usually requires an enzyme called chymosin, which comes from something called rennet.

In the case of Parmesan and most cheeses, that rennet is taken from the stomach of a calf.

For this, the baby cow is killed so that its stomach can be taken and separated, dried, diced and added to the cheese mixture.

This stomach enzyme is so important to the production of Parmesan that it cannot legally be called "Parmesan cheese" unless it contains cow's milk, salt and beef rennet.

And parmesan is not the only cheese that contains beef rennet. Grana Padano and Gorgonzola are other Italian rennet cheeses in the recipe.

Other cheeses that are not considered vegetarian include Gruyere, Manchego, Emmenthal, Pecorino Romano, Mimolette, Camembert, Boucheron and Vacherin.

Vegetarian cheeses, meanwhile, are made using rennet from either fungal/bacterial sources or genetically modified microorganisms.

Within the EU, cheeses cannot be described as parmesan unless they are made in the usual regions of Italy according to the three-ingredient recipe.

Source: Insider