Everything you think you know about parmesan cheese is a lie
The pasta-lovers staple actually contains an enzyme produced in calves' stomachs called rennet, BuzzFeed reported. When calves are killed for meat, rennet is harvested from their stomachs.
Rennet is key to producing hard cheeses such as parmesan, Gruyere, and manchego, as it allows the dairy to clump together and harden.
Fortunately for vegetarians, many parmesan cheeses in the US now use a nontraditional rennet, made using fermentation or microbes. Cabot Cheese, for example, only uses microbial-based enzymes in producing its cheeses and is vegetarian approved.
Unfortunately, it is often unclear if cheeses use enzymes harvested from the stomachs of calves, or if they are in fact vegetarian. The label of Kraft Parmesan Cheese, for example, simply says the cheese contains "enzymes." Kraft didn't respond to Business Insider's attempt to clarify if the cheese was vegetarian or not.
The vegetarian question is really just scratching the surface of parmesan cheese's modern identity crisis.
In Europe, what cheese can be labeled as Parmigiano-Reggiano is strictly regulated. Parmigiano-Reggiano can only contain milk produced in a certain part of Italy, using a time-intensive and exact method. In the US, however, generic parmesan cheeses made with different types of milk and different ingredients is both legal and common.
"These legal imitations won't harm anyone physically," Kevin Loria wrote in Tech Insider. "But they do affect the reputation and livelihood of the people who dedicate their lives to making these foods. Perhaps even more importantly, the bland imitations of food created largely by our system of mass-production are largely flavorless."
These issues came to a head in a 2016 scandal, when Bloomberg tested several brands of grated parmesan and found that all of the cheeses contained an anti-clumping additive made of wood pulp. While the additive, cellulose, is legal and safe, customers freaked out when they realized their 100% parmesan cheese contained something other than cheese.