Food has been packaged into metal cans since the early 1900s. Drink cans for both carbonated and non-carbonated soft drinks are the primary use of metal food packaging. Metal cans may either consist of tin plate (steel covered in a thin tin layer) or of aluminum and steel coated with a lacquer. Tinplate has reducing abilities preventing color and flavor loss as well as product oxidation.
For product types where oxidation prevention is less necessary, lacquers have been introduced to protect the food from migration of the packaging material.
The lacquers are on a polymer basis such as epoxy resins and may also migrate into the food. Cans can be extruded, drawn or welded (only possible with steel) and usually consist of two to three pieces, which are connected by seams. Even in non-lacquered cans, it is considered useful to seal the metal seams with lacquer in order to protect the food from contaminants from outside the packaging material"