Abstract

The primary purpose of food packaging is to protect food against environmental contaminants. Each food category, eg, ambient temperature shelf stable, frozen, or chilled, has different requirements. Generally, product processing must be integrated with the package to optimize shelf-life objective. Thus canned foods are both heated and hermetically sealed to exclude microbiological recontamination; dry foods are sealed against moisture access; frozen foods must be maintained at low temperatures and protected against moisture loss; and chilled foods are refrigerated while controlling the transmission of both moisture and air.

The most widely used packaging materials are paper and paperboard employed mostly in distribution channels. Second are metals; aluminum for cans to contain carbonated beverages and beer dominates in this category. Steel is applied for vacuum packaged foods. Glass has been declining as a package material because of weight, relative fragility, and high energy consumption. Plastic materials constitute only about 20% of the mass of package materials, but contain proportionately larger amount of food because of low densities and exceptional surface-to-volume ratio to achieve functionality. A variety of plastic materials is used for packaging depending on the food requirements, eg, polyethylenes, polyesters, polypropylenes, polystyrenes, nylons, poly(vinyl chlorides), etc. Among the structures employed are extrusion and injection blow-molded bottles, thermoformed trays and cast or blown films. High gas barrier plastics are coated, coextruded, or laminated to structural plastics to enhance properties.