If you have any difficulties with your milk setting when making a rennet based cheese (e.g. mozzarella) you should add another 1 scoop of rennet (dissolved into 1/4 cup water), warm the milk to 100°F and allow it to set for a further 30 minutes.
For customers in the USA please also read the below tips:
A number of customers in the USA have been experiencing difficulties with the curds setting in their mozzarella. We test all our recipes using fresh whole supermarket milk bought in the UK, but the ways which milk is processed does vary quite a lot around the world. This is particularly an issue in the USA, where a slightly higher amount of rennet may be needed to set the cheese. Please read through the bullet points below if you're having difficulty getting your milk to set.
- You should use whole cow's milk for your mozzarella, which shouldn't be labeled UP (ultra-pasteurized). Be wary of organic milks, many of which are actually ultra-pasteurized. If you find that the milk you're using doesn't work, then we would recommend trying a different brand.
- You should also be sure to dilute the rennet in non-chlorinated water, as chlorine can cause the rennet to become inactive. You can either use distilled water, bottled chlorine-free water, or water which has boiled on the hob for 20 minutes and allowed to cool.
- If your mozzarella hasn't set, then we would recommend not discarding the curds and instead adding a little extra citric acid and heating until the milk coagulates and turns into ricotta!