Pasteurized vs UHT milk: what's the difference
Both methods heat milk to kill pathogens, but at different temperatures and for different times. The method determines the shelf life and whether the milk needs refrigerating before the pack is opened.
| 🥛 Pasteurized milk | 🥛 UHT milk | |
|---|---|---|
| Heat treatment | High-temperature short-time pasteurization (HTST): 71.5 °C for 15 seconds, or 63 °C for 30 minutes | About 135 °C for 1–2 seconds |
| Shelf life | About two weeks in the fridge | About three months unrefrigerated in special aseptic packaging |
| Packaging | Ordinary containers; must be kept cold | Aseptic packaging (such as multilayer cartons); aseptic Tetra Pak cartons appeared in 1961 |
| Safety | Pasteurization effectively kills pathogens from raw milk without significantly affecting nutritional value (FDA) | Almost sterile until the pack is opened |
| History | Pasteur proposed brief heating for wine in 1864; Franz von Soxhlet proposed it for milk in 1886 | Industrial plants from the 1950s–1960s; UHT milk became widely available in the 1970s |
| Popularity | Common wherever there is a well-developed cold chain | In Europe, about seven in ten people drink it regularly; less popular in northern Europe and Scandinavia |
Which to choose
If you'll finish the milk in a few days and have a fridge to hand, pasteurized milk will do. For stocking up, travel and places without reliable refrigeration, UHT milk is more convenient. Once opened, both kinds are kept in the fridge.
Sources
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