🫙 Tetra Pak

A carton package (Tetra Pak-type carton) is a multilayer paperboard pack for milk, juice and other liquid foods. About three quarters of it is paperboard; the rest is layers of polyethylene and thin aluminium foil. In its aseptic version, a carton of UHT milk sealed under sterile conditions keeps for months without a fridge.

The layers work together. Paperboard gives shape and strength, polyethylene keeps liquid in, and the foil blocks light and oxygen. A typical sequence from the outside in is: polyethylene, paperboard, polyethylene, foil, and two more layers of polyethylene that touch the product.

The name comes from the Swedish company Tetra Pak, founded in Lund in 1951. The first packs were tetrahedrons — small pyramids with four triangular faces: from November 1952 a local dairy cooperative sold cream in them, one decilitre at a time. A machine for aseptic filling of milk was presented in 1961, and a brick-shaped aseptic carton appeared in 1969.

“Aseptic” means that a sterile product is filled into sterilised packaging without exposure to microbes. This is how UHT milk is packed: in a 2019 study it kept its quality for 34–36 weeks at 4–20 °C, but only 16–20 weeks at 30–37 °C.

Why it matters to you. Cartons can be recycled: a 2021 review in the journal Recycling calls the belief that this is impossible wrong. The paperboard fibres are separated in water, and the leftover polyethylene and aluminium is recycled too. According to an industry estimate, 51% of these cartons were recycled in the EU in 2019, so put them out separately if your community collects them.