A. In general terms, pasteurization is the process of heating a food, usually a liquid, to a specific temperature for a definite period of time, then cooling it immediately.
Pasteurization is the main reason for milk’s extended shelf life. It has been one of the most beneficial and cost-effective measures to protect the health of the consumer.
Dairy processing plants use three methods to pasteurize milk:
1. High Temperature Short Time (HTST) Method
- milk is pumped rapidly through a series of steel plates
- milk is heated to 72°C and held no less than 16 seconds
- then it is rapidly cooled to 4°C
- a continuous-flow pasteurizer is used to achieve this precise temperature control
2. Batch-Holding Method
- uses a paddle or coil in a large vat to agitate the entire batch of milk as it heats to62°C
- the milk is held at this temperature for 30 minutes before being cooled to 4°C
3. Ultra High Temperature (UHT)
- whole or partly skimmed milk is heated to 138°C – 158°C for one or two seconds
- milk is quickly cooled and placed, under sterile conditions, into pre-sterilized containers
- an unopened package of UHT milk will keep for three months with very little change in flavour and quality
- once opened, milk should be refrigerated and used within one week