Fresh milk is preserved by pasteurisation (heating to min. 72 °C for min. 15 seconds), after which it can be enjoyed for at least one week with no loss of taste.
There are two ways to preserve milk for even longer periods:
1) Longer shelf life through heating to a higher temperature = ESL milk
People who do not go shopping regularly and do not like the "cooked" taste of UHT milk, have a perfect alternative in the form of ESL milk. ESL stands for "extended shelf life", which means that you can keep it in the fridge for longer. ESL milk remains "fresh" for up to 4 weeks, so it ranks between pasteurised milk, which can be kept for 5–6 days, and UHT milk, which can be kept for over 3 months. In order to preserve ESL milk – the cross between fresh and long-life milk – it is heated to 125 °C for only 10–15 seconds and then cooled instantly. This process retains the vitamins and nutrients in the milk to a large extent, along with its fresh taste. So those who want to keep their milk fresh-tasting for longer are well served by ESL milk.
2) Even better "longer fresh" = microfiltered milk
In this process, the milk is filtered before pasteurisation, allowing a refrigerated shelf life of three weeks to be achieved without further heating. The shelf life can be extended by two weeks, because the filtration step uses very fine screens to filter out spores and germs that cannot be killed by pasteurisation.
Microfiltered milk provides three significant benefits for consumers:
• Three-week shelf life (two weeks longer than fresh milk)
• Same taste as whole milk (because the milk is not heated to a higher temperature)
• Milk fat, protein, vitamins and trace elements are all retained