🔄 Filling

Filling is packing finished milk into containers: cartons, bottles, jars and cups. It is the last step at the plant before labelling and shipping to the warehouse.

After cooling, pasteurised milk is collected in buffer tanks, and from there it goes to filling. The key things here are cleanliness and cold, so that no new germs get into the milk. UHT milk is filled aseptically: the packaging and the product are sterilised separately, then brought together and sealed in a sterile zone. Otherwise all the benefit of the strong heating would be lost. With sterilised milk it is the other way round: it is first filled and sealed, and then heated right in the bottle or jar.

Packaging must protect milk from light and oxygen. Light destroys vitamins and gives an off taste, so an opaque carton protects better than a clear bottle. Cardboard milk cartons were invented in Sweden: the tetrahedron appeared in 1952, the aseptic version in 1961, and the familiar “brick” in 1963.