Other food products such as cut vegetables, fruit, bakery goods, fish products, coffee and snacks are increasingly being packed in gas. Packaging in gas extends the microbiological life of products that are stored chilled and protects against quality defects such as rancidity and discolouration. This packaging technology enables centralised packing at the factories where the products are made, with a high level of quality assurance of the packaging itself. Good results with gas packaging depend on hygienic handling of the raw materials and maintaining an unbroken cold chain.
By selling prepacked goods, the retailers can save on packaging and staff costs. Wastage of food in the value chain is limited, mainly because extended shelf life means less food thrown away. Gas packed products are labelled "Packed in a protective atmosphere".
Packing in a modified atmosphere means using the same gases as are found in air, but in different concentrations. During the storage of foods in modified atmospheres, the composition of the gas mixture will change because individual gases are absorbed or converted in the food product and because gases are transmitted through the packaging to varying degrees. For some foods, such as meat, it is important to use packaging that is an efficient gas barrier, so as to best maintain quality. For other foods, such as vegetables, we need packaging that allows air with oxygen (O2) to pass through, so that the vegetables can breathe or respire. With quite low levels of O2 in the pack, equilibrium will gradually be established.
The most important gas is carbon dioxide (CO2), since this reduces the growth of many types of bacteria. For many food products it is also important to remove O2, both to limit bacterial growth and to prevent quality defects. There are exceptions, such as using high levels of O2 with lean fish to limit odour development or with meat to create a red colour. Nitrogen (N2) is used as a filling gas in the gas mixtures for many food products. Determining the ideal composition of gas mixtures for different types of food requires considerable knowledge and experience.
By clicking on the following links you can find out more about gas packaging of various food products.
