Packaging

Traditionally, food for retail was packaged in cans, glass, paper bags and cartons. Whatever was used the integrity of the package was essential, because foods rely on it to protect the product from spoilage and the consumer from harm. Total protection may be bought at a price, but the cost of packaging is always of major concern. Over-packaging loses money and under-packaging loses money, too, in damage to product in transit and loss of confidence by the consumer. The wooden case and the paper bag, both single and multi-walled, have disappeared and a lot of attention has been given from the 1950s to optimum package design. Systems have been developed to determine how packages, especially outer cartons and flexible films, behave during transport and on storage under various climatic conditions and the results obtained, both chemical and physical, have been used greatly to improve the design and performance of both.

Mention has already been made of changes to metal cans and Australian food technology has rapidly adapted to them. Light weight glass and variations on the way in which glass containers are closed have been absorbed also. The modern paperboard carton for liquids developed from waxed cardboard containers which were introduced overseas in the late 1930s. This carton did not come to Australia until after the Second World War, but, now lined with polythene, it is familiar today as a light-resistant container for milk and fruit juices.

The post-war revolution in packaging flowed from the sudden surge in plastics which offered lower costs and greater eye appeal. Food technology relied on chemical technology for these new packaging materials and they were offered as flexible films and rigid containers. Films of various properties were laminated with each other and with metal foil. They could be designed and manufactured to satisfy many different specifications and they could take print. They were rapidly adopted for low moisture foods, for cheese, as already noted, and in due course, for meats and as collapsible liners for wine 'casks'. Their design called for the measurement of gas transmission rates of, especially, water vapour, oxygen and carbon dioxide, the selection of the correct heat sealing properties and the resistance as far as possible to the stresses of long distance transport. Their use required careful machine adjustment especially of the heatsealing elements.

The introduction of heat-shrink wrappers has been a particular boon to the flourishing post-war poultry industry and has facilitated the transport of stacked pallets of finished products, especially protecting open cans and glassware between the makers and the food processors. This particularly applies to individual serves (portion controls, or PCs) which were introduced to Australia about 1960 by Kraft. They have to be sealed well enough to preserve the integrity of the product but not so well that the consumer cannot open them. Retortable pouches, which require less processing time were introduced overseas but suffer from some serious disadvantages; their use in Australia thus far (1986) has been very limited. Rigid plastic containers have been enthusiastically adopted for many products both liquid and high moisture. Vinegar, cooking oil and beverages appeared in plastic bottles and it is not too much to say that the boom in yogurt and similar products was made possible by the cheap rigid plastic container.

Australian Academy of Technological Sciences and Engineering