Pasteurisation was invented by the French scientist Louis Pasteur during the nineteenth century. Pasteur discovered that heating milk to a high temperature and then quickly cooling it before bottling or packaging could keep it fresh for longer.
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Today, the process of pasteurisation is widely used within the food and drink industry, and it is the most common form of heat treatment used for milk in Northern Ireland. Pasteurisation makes sure milk is safe to drink (by killing any harmful bacteria) and also helps to prolong its shelf-life.
The process of pasteurisation involves heating milk to 71.7°C for at least 15 seconds (and no more than 25 seconds). The nature of the heat treatment means that it is sometimes referred to as the ‘High Temperature Short Time’ (HTST) process. Once the milk has been heated, it is then cooled very quickly to less than 3°C. The equipment which is used to heat and cool the milk is called a ‘heat exchanger’.