ball cooksup microwavable steel can  the material will allow processors to offer products in a packaging material suited to the convenience food segment, which continues to show strong growth. microwave energy cannot pass through steel, making the material traditionally unsuitable for products meant to be cooked this way. conventional microwavable food is packaged using polymeric or paperbased materials transparent to mocrowave radiation, but the shelf life is considerably lower than food packaged in steel.