Approximately 80% of all food products are sensitive towards loss or uptake of water vapour, flavours, and odours. These food products must therefore be stored in a protected environment from one or more of these gases. Especially oxygen can pose a serious problem since oxygen penetration into food packages are known to be detrimental to the flavour, texture, colour, nutrition, and/or shelf life of the food. Oxygen enters into many reactions which affect the shelf life of foods, e.g. microbial growth, colour changes in fresh and cured meats, oxidation of lipids and consequent rancidity, and senescence of fruit and vegetables. The shelf life of many foods is therefore determined by the oxygen transmission rate (OTR) of the material used to package the food, especially during long-term storage.
It is estimated that in 1991, more than 10 000 new food products were introduced in the US alone, a market where total sales amounted to billions of USD per year. Food products are typically sold in small units that often are individually packed. Thus the cost of the packaging material becomes a vital competition factor, and it has become increasingly important to find materials with an optimal balance between price and barrier properties against these gases.
This challenge has resulted in an increased use of barrier packages within the food industry, since they provide a cost efficient and practical manner of packaging food products while offering good protection from detrimental gases in the ambient air. The “barrier plastic” portion of the food packaging market is the fastest growing segment, and there is a world wide activity in achieving new and improved plastic barrier materials for food packaging, which can offer better protection against gas penetration and longer shelf life for a wide range of products.
As a result, there is a dramatic increase of the number and types of barrier plastic packages being made available for the package designers. The resultant challenge, then, is to quantify the demand of the food to be packed, and to match the proper barrier material to that particular application. Thus there is a growing demand for testing the barrier properties of package materials, especially for the oxygen transmission rate (OTR).