Modified Atmosphere Packaging (MAP) is a well-established packaging technique which, when used in conjunction with refrigeration, helps to keep food safe and fresh. By using a specially selected combination of gases (usually those naturally present in air - i.e. oxygen, carbon dioxide and nitrogen) within the product pack, MAP can increase the shelf life of certain foods. The combination of the gases depends upon the type of food, its fat content, microbiological character and other factors.
MAP is used to preserve many types of chilled foods from meat and fish to prepared leafy salads and prepared fruit and vegetables. It requires high quality raw materials, strict temperature controls and specialised equipment. As a requirement of membership CFA members must comply with tough industry guidelines that cover the standards and procedures required. These standards are well established and enforced commercially. Safety and quality is further assured through strict temperature control and short shelf lives.
Under EU law, foods packaged using MAP must be labelled with the phrase 'packaged in a protective atmosphere'.
The Deparment of Health recommends the consumption of 5 fruit and vegetables per day as part of a healthy diet. Salad vegetables can make an important contribution to our fruit and vegetable intake. For some varieties, MAP helps provide all year round access to salad vegetables that may otherwise not be available by ensuring that they reach the consumer in an optimum condition.
Despite some suggestions to the contrary, MAP has no direct impact on vitamins (C Barry-Ryan and D O'Beirne 1999. Ascorbic acid retention in shredded iceberg lettuce as affected by minimal processing. J Fod Sci Vol 64 No 3, pp490-500).
In practice most prepared salads in the UK are packed in air only as very few varieties of lettuce (iceberg and cos) benefit from using MAP. Rapid preparation and chilled distribution of prepared salads together with their short shelf lives minimises the loss of vitamins.
