What is the role of rennet in cheesemaking?

Rennet plays a crucial role in the cheesemaking process by coagulating the milk, which is the primary step in transforming liquid milk into solid cheese. It contains enzymes, primarily rennin (also known as chymosin), that cause the proteins in milk, specifically casein, to curdle. When rennet is added to milk, the enzymes interact with the whey proteins and caseins, leading to the formation of curds, which are the solids that eventually become cheese.

This coagulation process is essential because it allows the separation of solid curds from liquid whey, paving the way for further processing, which may include cutting, cooking, pressing, and aging the curds. Each of these steps ultimately contributes to the texture and flavor of the final cheese product.

The other options presented do not accurately describe the function of rennet: it does not directly flavor the cheese, age it, or play a role in pasteurization, which is a separate heat treatment process used to eliminate harmful bacteria from milk before cheesemaking begins.