the (un)clean cut on rennet

Twice in the past two months since the start of my production, I have been asked about my choice of rennet. Twice, I’ve had to disappoint two conscientious vegetarians who were saddened to hear I use veal rennet. While this is not a significant hit rate (and, at that, both customers admitted to “cheating” and buying the cheese anyway), I was intrigued to dig a little deeper into the subject. Since rennet is an essential part of my cheesemaking practice, I wanted to know more about the choice I make every day, often twice a day when I dilute a few millimeters of syrupy brown liquid in water and stir it into a 40-gallon vat of fermenting milk.

Let me preface the conversation by admitting that I was drawn to veal rennet for a couple of primarily indulgent reasons. First, the word on the street has always been that alternative rennets can cause bitterness in cheese. Having a sweet tooth myself, I decided this was not to my taste. 

Second, I had a warm and fuzzy feeling about finding use for the dismal byproduct of the dairy industry: male calves. It is known to most that the only reason veal exists in this country is a result of dairy. What to do with the young, male calves who will not grow up to be milkable? Let’s turn them into tender, young meat. Eating dairy means not-so-indirectly fueling the veal industry. (I, too, still have a hard time digesting this quandary.)

And finally, I am a traditionalist by nature. I think back to the man or woman who made the earth’s first cheese, surprised to open his or her calf-stomach storage sack and find that the milk had curdled. (Actually, Egyptian tomb murals show cheese being made as early as 2000 B.C.). The enzyme in the fourth stomach of the unweaned calf exists to help it digest its mother’s milk, and humans were smart to discover that this enzyme can be used in the coagulation of milk for cheesemaking. Veal rennet is nothing more than these fourth stomachs, cleaned, dried, sliced and rehydrated in a salty, slightly acidic brine to create the liquid form.

Surely, that does not sound appetizing, but it makes intuitive sense. And if one were to examine the rennet options available on Dairy Connection’s website, the option of Veal Rennet has the simplest and most alluring description to the purist: 100% natural veal rennet. 

Natural, but not vegetarian.

The alternatives, which are vegetarian friendly options, are not quite as natural, and require a little more color.

The first alternative to veal rennet is microbial rennet, often coming by the name Marzyme and manufactured by a company called DCI. Microbial rennet is derived from a fermentation of mucor miehei, or mold. These molds are produced in a fermenter and then purified and concentrated for commercial use. Microbial rennet is known to cause some bitterness and off flavors in cheese, and is also rumored to be a less stable source of coagulant, but it is suitable for vegetarians so long as no animal products were used in its manufacture.

Because of the imperfections with microbial rennet, producers sought an additional alternative. Enter: CHY-MAX. With the development of genetic engineering, it became possible to extract rennet-producing genes from animal stomach and insert them into certain bacteria, fungi or yeasts to make them produce chymosin during fermentation. According to Wikipedia, “The genetically modified microorganism is killed after fermentation and chymosin isolated from the fermentation broth, so that the fermentation-produced chymosin (FPC) used by cheese producers does not contain any GM component or ingredient.” In conclusion, this version is suitable for vegetarians but flirts with the line between natural and genetically modified ingredients. Further, the ultimate source of the rennet is still being extracted from animal, so while it does not contain any animal matter in its final form, it still depends on animals for its manufacture.

With this knowledge, I stand a little taller in my decision to use veal rennet as my primary coagulant in cheesemaking. It's not a squeeky clean choice, but one that suits my style and aligns most closely with my ideals: that is, to be as pure and traditional as possible in my ingredients and in my process. 

And there you have it: way more detail than you ever wanted to know about rennet, but here for your bedtime reading nonetheless. While I do not have all of the answers to the big paradox around eating dairy and conscious eating, at the very least, I’ll try not to eat my words.