Background 
Casein is the chief protein in milk and an essential ingredient of cheese. When rennet is added to warm milk it will cause the casein to curdle. To curdle 125 mL of reduced fat milk (1.5% fat), you would use 4 drops of rennet.

How to do this task 

• You are the research chemist for a dairy company. The company is going to write pamphlets on how to make cottage cheese. Part of making this cheese involves the curdling of the casein in milk by using rennet. The pamphlet needs to tell those making the cottage cheese what would be a good temperature to have the milk at before adding the rennet. 
• Your job is to trial milk temperatures of 15° C, 30° C, 45° C, and 60° C. You want the milk to curdle in a reasonable time, and for this product not to be too runny or too tough.
• For each trial use 125 mL of milk and 4 drops of rennet. 
• Carry out your trials and record all observations. 
• Finally write up a report for the dairy company recommending a temperature, and the reasons for this choice.