Internal corrosion in food cans is characterized by metallic dissolution which is an electrochemical reaction. In lacquered cans, corrosion may also cause disruption in the continuity of the lacquer film. These reactions may cause organoleptic changes in the product, loss of vacuum, swelling, and leaking in extreme cases. In some instances the metal dissolution (i.e., lead) may give rise to toxicological problems. Therefore, these phenomena are often the limiting factor in the shelf life of canned products. Changes in color, texture, and sensoric properties of the foods, which take place simultaneously, affect the aesthetic and nutritional value of the product and thus its shelf life. These changes are often related to interactions with the container. For example, tin dissolution prevents browning and loss of ascorbic acid. Shelf life of canned foods is governed by the quality of the raw materials, the processing technology, quality of the container and storage conditions which will be reviewed in this paper. Can manufacturing technologies, mechanisms of electrochemical corrosion, methods of their measurement and prediction of shelf life will be discussed.
Most food products can interact to some degree with their packaging. Migration, permeation and absorption are the mechanisms that determine the extent of this interaction, which is affected by temperature, storage time and other environmental parameters.The major challenge facing food and packaging manufacturers is to ensure the wholesomeness and safety of their products, so that the package-related factors, including chemical and physical integrity, will be controlled, ensuring that a safe product reaches the consumer in optimal condition.Keywords: Food-package interactions; migration; permeation; absorption I NTRO DU CTlO N Package manufacturers are facing the challenge of producing safe and wholesome packaging materials to ensure minimal interaction between food and package.The rapid change from hermetic and relatively inert rigid glass and metal packages to more interactive and not 100 % gas-tight synthetic polymers has brought forth new problems concerning interactions between foods and their packages.Plastic materials are not inert and where direct contact between the packed commodity and the plastic container occurs, there can be transfer of sufficiently mobile or soluble substances into the product as a result of a concentration gradient. These substances may be polymer additives and/or other adventitious impurities, such as monomers, catalyst remnants, polymer breakdown products and residual polymerization solvents. This transfer may introduce the risk of toxic hazard and/or formation of off-flavours. The actual hazard arising to the consumer from any extractable material into the food is a function of the toxicity of the extracted material and the amount extracted from the polymer that enters the packed food during packaging and storage.Interactions between foods and the packaging materials may be classified into the following categories:(i) Migration or transfer of components from the package into the foods during preparation or storage; (ii) Permeation of gases, organic vapours and water vapour through the package; (iii) Absorption of components from the food into the package.
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