Curd Formation . Most varieties of cheese are produced by enzyme coagulation or rennet. Rennet coagulates milk by precipitating casein. After the curd is formed, the enzyme is either inactivated or expelled with the whey. The specific starter culture depends on the type of cheese being produced.
Cheese made by acid coagulation tends to be unripened.
The temperature for coagulation of milk is carefully controlled and varies with the type of cheese being made. The combination of the temperature of coagulation, the starter culture, the coagulating enzyme, and the acid produced influences the rate of formation, the firmness, the elasticity, and other physical properties of the resulting curd and the degree of whey expulsion. Cutting or Breaking Curd . This process speeds whey expulsion and permits more uniform, thorough heating of the equal-sized smaller curd. The curd particles are cut into various sizes depending on the variety of cheese being made.