Rennet 101

As a basic aspect to cheesemaking, it is necessary to separate the curds from the whey. Once the milk reaches the proper pH, a substance called rennet is added to coagulate the milk proteins into curds. Rennet is largely comprised of rennin, an enzyme found in the fourth stomach of ruminant animals. Most animal rennet is derived from unweaned calves. Animal rennet is a key ingredient in a great variety of cheeses, and many believe it furthers the development of complex flavor and texture during maturation. However, inconsistent supplies of animal rennet and increased market demand for animal-friendly products have caused several vegetarian alternatives to appear. The most widespread variants are vegetable rennet and microbial rennet.

Non-animal rennet has appeared mainly in response to increased vegetarianism, lack of calf rennet supply, advances in bioengineering, and local availability of plant sources.  Of this sort of rennet, there are three main types: vegetable rennet derived from plants such as thistle or fig leaf, microbial rennet derived from cultured fungiform microorganisms, and genetically modified (GMO) rennet, a lab-engineered derivative of animal rennet. Vegetable and microbial rennet enjoy a much greater market share, primarily due to the negative connotations consumers associate with GMOs.

Here at Artisanal Premium Cheese, we stock several fine examples of cheeses containing non-animal rennet. Our best vegetable rennet cheeses come from Spain and Portugal, including Azeitao, Serra da Estrella, Torta del Casar, and La Serena. The milk for these cheeses is uniquely curdled using a cultivar of the thistle plant. Our selection is just as well rounded when it comes to microbial rennet cheeses: Great Hill Blue from Massachusetts, Berkswell, and Purple Haze and Humboldt Fog from Cypress Grove Chèvre in California.

I hope you enjoy our vegetarian friendly selection of fermented dairy delights.

Sources:

Mcgee, Harold. "On Food and Cooking: the Science and Lore of the Kitchen" (Second Edition, Scribner, 2004)

Dairy Microbiology Handbook: The Microbiology of Milk and Milk Products, 3rd Edition Richard K. Robinson (Editor)