📅 Shelf life

Shelf life is how long a food can be safely stored and eaten. For milk it varies a lot. It all depends on how the milk was treated and packed, and whether it was kept cold.

Raw milk keeps for only a day or two in the fridge. Ordinary pasteurised milk is heated to about 72 °C for 15 seconds. Kept cold, it lasts from a few days to two weeks. Ultra-pasteurised (UHT) milk is heated to 135–150 °C for a few seconds and filled into sterile packaging, such as a Tetra Pak carton. Unopened, it can keep for six months or longer, even without a fridge. Sterilised milk keeps even longer. Milk powder and tinned condensed milk also last a long time: one has little water, the other a lot of sugar, and germs cannot grow in them.

It is important to check the label and the storage instructions. Once opened, any kind of milk must be kept in the fridge and drunk within a few days. The CDC advises keeping perishable foods at 4 °C or colder and not leaving them out in the warm for more than two hours. If milk smells sour or has curdled, it is best not to drink it.