Rennet can usually be bought at local health food store and is readily available online, according to About.com. About.com recommends purchasing rennet from New England Cheesemaking Supply. As of April 2014, its website lists both animal and vegetable rennet, some of it organic, in liquid, tablet and powdered form.Continue Reading
About.com reports that rennet has traditionally been made from animal sources: "Specifically, the stomach lining of young animals that have been butchered." Young animals are required because the enzyme needed, chymosin, is found in their stomach lining to assist in the digestion of their mother's milk. Enzymes are extracted from the stomach lining of a calf, ewe or baby goat that was butchered for food. Cheeses made from animal-sourced rennet typically list "traditional rennet" as an ingredient, but the FDA does not require cheesemakers to disclose the type of rennet used, according to About.com.
Other sources of rennet are also available. Rennet can be produced from plant sources. Microbial rennet is produced from mold. These types of rennet do not produce reliable results and are not used as frequently. Genetically engineered chymosin begins with an animal cell but does not necessitate the butchering of the animal. According to About.com, "this type of cost-effective and reliable rennet is widely used in cheesemaking."Learn more about Grocery