For Mozzarella to stretch well it needs two things:
- The right amount of heat to soften the curd
- The right acidity (pH of approximately 5.2)
For the heating step make sure the heat is very low. When the water temperature reaches 42°C (100°F) if the curds are still soft and look like they will disintegrate, take off the heat until the curds are springy to touch and look a little shiny.
The curds will not hold the shape of a cube, they will almost form one mass in the pot.
The right acidity of the curd will be determined by following the instructions and ensuring that all ingredients are added. If you have pH strips and can measure the pH of your milk prior to adding your rennet this is a good idea. You can adjust the pH by using your pipette and adding small amounts of lemon juice or white vinegar.