As Americans' eating habits continue to change, and as food distribution and merchandising methods evolve, the demand for packages which protect food from physical, chemical and microbial damage is stronger than ever. Rigid and flexible barrier containers, some able to resist retorting conditions or the temperature extremes of freezer-to-oven applications, are increasingly commonplace. In addition, refined technologies for extending shelf life through hot filling or aseptic processing have further broadened the range of shelf-stable products.