We all know the popular nursery rhyme about Little Miss Moffett eating her curds and whey, but you might not be quite as familiar with rennet. Simply put, rennet is an enzyme that coagulates milk and separates it into the aforementioned curds and whey. But where does it come from, and what does it do for the cheese?
Coagulation is the first step of cheesemaking, separating the solids (curds) from the liquid (whey) so that the solids can be manipulated in different ways, eventually resulting in cheese. Some cheeses are lactic- or acid-coagulated, meaning that the action is caused by lactic acid bacteria present in the milk. But many cheeses, including most hard or aged cheeses, are made with rennet. Rennet-coagulated cheeses use animal (or "traditional"), microbial, or vegetable-based rennet.
Traditional rennet is derived from the 4th stomach, or abomasum, of a young ruminant animal. Vegetable-based rennet can be derived from plant-based sources like thistle, and microbial rennet is grown in a lab using live organisms like mold, yeast, or fungi.
Each version has benefits - while traditional rennet is better for longer-aged cheeses, microbial rennet is suitable for vegetarians, and is also cheaper to produce, which decreases the cost of cheesemaking. Thistle rennet is more common in torta-style cheeses from Spain and Portugal, and lends an herbaceous flavor to the cheese. Some cheesemakers use combinations of different types of rennet to achieve their desired texture and flavor.
If you're interested in tasting some cheese made with different types of rennet, consult your local cheesemonger! They are a wealth of knowledge and can guide you through your options, as well as give you samples to taste. If you're searching for a vegetarian-friendly cheese, we recommend that you try an American cheese! The USA produces the highest number of vegetarian rennet cheeses in the world, second only to Portugal. If you don't have access to a cheesemonger, check the packaging on your precut cheeses - it will likely denote what kind of rennet is used during cheesemaking.
Once you've selected your cheese, don't forget to add a package of Formaticum Cheese Storage Bags to your basket as well, to preserve the flavor of your newest discovery.