Special bonds are routinely broken and cows often develop painful medical conditions. Just like humans, cows only produce milk for their offspring. Therefore, they are forcefully impregnated every year. A female and her offspring are forced through a cycle of cruelty that ends with their slaughter.

Most stomach-derived rennet is taken from the fourth stomach of young, unweaned calves. These animals are not killed expressly for their rennet; rather they are killed for meat production (in this case, veal) and the rennet is a byproduct.

As the calves get older the amount of chymosin reduces and other enzymes take its place (those necessary for digesting other foodstuffs). This is why you can get various quality grades of rennet depending on how much chymosin is present: 100% chymosin from a young unweaned calf is the Cadillac of rennets.

Animal rennet is better for longer-aged cheeses, claims the website’s FAQ section, because residual components in the rennet help complete the breakdown of proteins in the cheese. Vegetable rennet may leave a bitter taste after six months of aging, but their product is kosher and repackaged under kosher supervision.

For example, vegetable rennet can begin to impart a slightly bitter taste to cheese after an extensive aging process (3+ months). It also may not be as easy to use as animal rennet, as it can produce somewhat inconsistent results that beginners may have trouble compensating for.

Some cheeses are, indeed, made without rennet, which curdles milk protein. A few varieties are made with no curdling agent at all, and others use plant-based forms of the enzyme found in rennet. There is also a rennet that is made from genetically modified fungi.

Calf rennet is extracted from the inner mucosa of the fourth stomach chamber (the abomasum) of young, nursing calves as part of livestock butchering. These stomachs are a byproduct of veal production.

Is rennet a pork? Does animal rennet for cheese come from PIGS? NO. Animal rennet must come from the same species of animal as the milk being used in for cheese.

When it comes to environmental impact, beef is by far the worst offender compared to other proteins. But, that doesn’t mean that cheese—or any dairy product—is in the clear. According to the Oxford study, “tenth-percentile GHG emissions and land use of dairy beef are then 36 and 6 times greater than those of peas.”

Rennet causes milk to coagulate, beginning the process of separating the solid curd from the liquid whey. Cheesemakers start the process of making cheese by introducing bacteria to milk that converts lactose to lactic acid. Rennet is then added to coagulate the milk.

In most cheesemaking, rennet is added to the milk either in liquid or paste form. Modern practices also incorporate rennet in tablet and powdered applications, a method that allows the ingredient to be stored longer in warmer climates.

Rennet contains an enzyme called chymosin that is traditionally obtained from the “abomasum” (fourth stomach) of a newborn calf or lamb. Adult mammals don’t have this enzyme — newborn calves and lambs need it to help digest and absorb milk. Almost all European cheeses still use animal rennet.

Rennet contains an enzyme called chymosin that is traditionally obtained from the “abomasum” (fourth stomach) of a newborn calf or lamb. Adult mammals don’t have this enzyme — newborn calves and lambs need it to help digest and absorb milk.