Rennet is the coagulant that is used to set a curd when making cheese. Traditionally rennet is made from an enzyme found in the stomachs of baby calves, goats or lambs. Vegetable rennets are obtained from a type of mold, and there are also plant-based rennets such Thistle rennet. Rennet comes in tablet, liquid and powder form.
To use your rennet, you first must dilute the desired amount in non-chlorinated water (we use distilled water but if you have a good filter on your water source, that will generally take all the chlorine out of the water). If using rennet tablets, just be aware that 1 tablet = 1 teaspoon and when you dilute it in the water it won’t actually dissolve. Use your diluted rennet within 30 minutes or it will lose its effectiveness.
Rennet has a limited shelf life – liquid rennet lasts for 7-8 months when refrigerated and tablets last for up to 2 years when stored in the freezer. If you are unsure how old your rennet is or whether or not it is still effective, you can do the following test:
- Heat one cup of milk to 90F.
- Dilute ¼ tablet or ¼ tsp liquid rennet in ½ cup non-chlorinated water.
- Take 2 tsp of the diluted rennet and add it to the milk.
- Stir gently for 30 seconds.
- If the rennet is working, the milk surface will form a slight film in 2 minutes and will have formed a firm curd within 6 minutes.
If not, it might be time to get some new rennet!
Submitted by Kate Johnson