Rennet for Cheese Making
What is rennet?
Traditional animal rennet is an enzyme derived from the stomachs of calves, lambs or goats before they consume anything but milk. (Ours is all from calves.) It is about 90% pure chymosin. Vegetable rennet is obtained from a type of mold (Mucur Miehei). However, even though it is derived from mold, there is no mold contained in the final product. It is an equivalent chymosin product which works equally well but is not animal derived. We have recently added organic vegetable rennet to our catalog. Rennet thrives at temperatures in the 85-105F range, but it won't be deactivated completely until it reaches the 140F's. Rennet continues working to set the milk as long as it has the right conditions. So, when a recipe calls for cutting the curds after a certain time period, it is important to follow the directions. Otherwise, your curds may be too firm for the cheese you are trying to make.
How do I choose which rennet to use?
Rennet is standardized, so all the different kinds of rennet (liquid, tablet or powder) work the same to set milk. Liquid is the easiest to work with because you can measure it very precisely. However, the powders and tablets will keep better under more adverse conditions. Calf rennet is considered to be the best choice for longer aged cheeses because some of its residual components help to complete the breakdown of proteins. Some of the more complex proteins in the vegetable rennet can have a slightly bitter taste after 6 months of aging. The liquid vegetable rennet is Kosher, but it has been re-packaged without Kosher supervision.
How much salt is in rennet?
The amount of salt in rennet is miniscule. It is there as a preservative. Considering that you add 1/4 teaspoon of rennet to a gallon of milk and that much of the rennet runs off with the whey during draining, the amount of salt left in the cheese is virtually impossible to measure. If you are interested in making cheese with no salt, the fresh cheeses, Mozzarella and Ricotta are best suited for this. The aged cheeses require a slight amount of salt to sow bacterial activity.