Hello Kurma, Can you tell me a bit about rennet in cheesemaking, and its usual sources, and specifically, where does vegetarian rennet come from, and is it genetically modified?
Sally Baker, Islington, London UK Hello Sally, Thanks for your letter about Rennet. Here’s some info: Cheese is made by coagulating milk to give curds which are then separated from the liquid, whey, after which they can be processed and matured to produce a wide variety of cheeses. Milk is coagulated by the addition of rennet. The active ingredient of rennet is the enzyme, chymosin (also known as rennin). The usual source of rennet is the stomach of slaughtered newly-born calves. Vegetarian cheeses are manufactured using rennet from either fungal or bacterial sources. Advances in genetic engineering processes means they may now also be made using chymosin produced by genetically altered micro-organisms. The exact processes in the making of cheese varies between different varieties. However, all cheeses are made by essentially the same method. Initially, the milk is usually pasteurised by heating at 72°C for 15 seconds to destroy potentially harmful bacteria. The milk is then cooled to
