Here are the results of an experiment at producing home made rennet.
Rennin is an enzyme which, in an acid environment, digests the water soluble milk protein casein into insoluble products. When these precipitate out of solution, the milk coagulates. The test is the famous “clean break” of cheese making.
Here, the abomasum of a suckling kid was cleaned, salted and dried. A small piece (0.75 gm) of it was suspended in warm water (30 C), and added to 1 gallon of inoculated milk. While a clean break was not achieved in three hours, by the evening (about 7 hours) the milk had formed a very firm coagulant.
This is my first attempt at using home made rennet. I am sure that the process and conditions can be improved. Let me know if you have suggestions.
See the bottom of the page for suggestions from Mr. Wolfgang Pachschwöll, of “Hundsbichler company Austria – producer of natural rennet.”
Here are some points of expert advice on making rennet from Wolfgang Pachschwöll of “Hundsbichler company Austria – producer of natural rennet”, sent in response to my initial posting of this page. (Thank you very much Wolfgang!)
1) Do not thoroughly clean out the inside of the abomasum. The “slime” inside contains rennin. Therefore, also no washing nor squeezing.
2) Lightly salt the abomasum, store undried with 30% salt in a closed container to activate the enzyme over three months. (Pepsin, another stomach enzyme, is also secreted in the inactive form (pemsinogen), and activated by acid or enzymatic action.)
3) The traditional way to then dry the abomasum is to inflate it like a balloon and dry by hanging in a cool dark place.
4) Dissolving and activation of rennin occurs best in acid conditions at a cool temperature.