Pasteurization involves heating the milk at a very high temperature for a brief period followed by rapid cooling. This method increases the shelf life of the milk by inactivating pathogenic microorganisms, microbes and milk enzymes responsible for spoilage. Pasteurized milk stored below 5 °C remains palatable up to 10-15 days.
Methods of Pasteurization
Batch Pasteurization: Fixed quantity of milk is slowly agitated in a heated chamber at 62°C for 30-35 min. This method has only mild effect on the flavor.
High-Temperature Short Time Method (HTST): Milk is passed through a heat exchanger at 77°C for 15 seconds followed by cooling. This is the preferred method for industrial use.
Using HTST method, 10% of the whey protein denatures and gives a ‘cooked milk’ flavor.
Ultra –High Temperature Method (UTH): The milk is heated at 130-150 °C for 1-3 seconds followed by cooling. You can store Milk packed under sterile conditions for months without refrigeration.
UHT treatment milk is slight brown color in color and gives a ‘cooked milk’ flavor.
Sterilized Milk: The milk is heated at 110-121 °C for 8-30 min and kept indefinitely at room temperature. This milk is darker in shade and has a strong flavor.