Answer:
Fresh milk, often referred to as homogenised and pasteurised milk, is sold in the chilled food section of the supermarket. It has a short shelf life and must be kept below 4°C to maintain freshness. Ultra heat treated (UHT) milk, which is sometimes called long-life milk, is slightly different. It has had extra treatment which enables it to be stored at room temperature (as long as it is unopened) for extended periods.
Both fresh milk and UHT milk have undergone pasteurisation and homogenisation before packaging and sale to consumers. Pasteurisation involves heating the milk to 72°C for 15 seconds to kill harmful bacteria that may be present. The milk is rapidly chilled, before homogenisation commences. This involves passing the milk through a fine nozzle to create a smooth, creamy taste and texture.
Fresh milk is then packaged and refrigerated, while UHT milk is exposed to a more powerful heat treatment to inactivate harmful bacteria. This allows the milk to be stored out of the fridge while it is unopened. It is important to chill UHT milk once it has been opened.
This information is provided by the Sanitarium Nutrition Service.
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