Yes, there is an aluminum layer used but it does not come into direct contact with the food contents. The Tetra Pak cartons are made up 6 layers which help protect the food contents from various environmental factors such as moisture and sunlight for example. This particular package helps ensure the product stays fresh for months without refrigeration when unopened.
These 6 layers are made up 3 main materials. The main material used is paperboard, a recyclable material made from wood. Polyethylene is another material used which serves as an adhesive between other layers. Polyethylene layers seal in the liquid and protect product from external moisture. The third material used in the package is aluminum, which forms a barrier against light and oxygen, eliminating the need for refrigeration and preventing spoilage without using preservatives.