Metal is the most versatile of all packaging forms. It provides excellent physical protection and barrier properties. It has got formability and decorative potentials. It is recyclable and got consumers’ acceptance. Aluminium and steel are most prominently used in packaging.
Aluminium is lightweight. Magnesium and manganese are added to aluminium to enhance its strength. Aluminium is highly resistant to most forms of corrosion. Coating of aluminium oxide provides an effective barrier to air, temperature, moisture, microorganisms and saves from chemical attacks.
Aluminium is flexible and surface resilience. It has got excellent malleability and formability. It possesses excellent embossing potential. It is easy to reclaim, therefore, ideal for recycling into new products. Pure aluminium is used for light packaging. It is ideal for packaging of soft drinks, pet food, and sea-feed.
Aluminium foils are prepared by rolling pure aluminium metal into thin sheets. It is, then, annealed to achieve dead-folding properties, due to which it can be folded tightly. Aluminium foils are used to wrap food. Thicker foils are used to prepare trays. Aluminium foils provide excellent barrier to air, odour, light and moisture. These are inert to acidic foods and do not require lacquer or other protection. It is easy to re-cycle.
Barrier properties of aluminium are enhanced by binding aluminium foils with paper or plastic films. As “laminated aluminium” is expensive, it is used to pack only high value foods, such as dried soups, herbs and spices. The solution is the use of less expensive alternative – metalized film. These are plastics containing a thin layer of aluminium metal. The reflective exterior of aluminium is attractive to consumers. These films provide improved barrier to moisture, air, odour and oil. Metalized films are used to pack snacks.