Which gases can be used for Modified Atmosphere Packaging?
Modified Atmosphere Packaging (MAP) is a process which uses gas to modify the atmosphere in food packaging. Read on to discover which gases should be used to meet your MAP goals.
When it comes to MAP, oxygen usually has a role to play. In most cases, MAP is being used in order to displace oxygen from the food packaging, in order to prevent food spoilage caused by oxidation and to inhibit the growth of aerobic organisms.
However, sometimes oxygen is the gas which the food’s atmosphere is modified to include more of. An odourless and tasteless gas, oxygen is commonly used with red meat where it is used during processing to keep the meat’s vibrant red colour and stop it from becoming pale. Using oxygen in this way also prevents the growth of anaerobic organisms.
Nitrogen is one of the most common gases used for MAP, mainly due to it being inert, odourless and tasteless. It’s also easy to obtain high quality food grade nitrogen, which can be generated on demand from a nitrogen generator. Food grade nitrogen has a purity of at least 99%, which makes it an ideal gas to displace oxygen, preventing food oxidation and the growth of aerobic organisms. Nitrogen gas is also very slow to diffuse through plastic film, so it is able to remain in packaging for long periods of time.
Argon can also be used although it is not as common as nitrogen for MAP. Like nitrogen, argon is inert, odourless and tasteless. However, unlike nitrogen gas, which can be generated onsite from a nitrogen generator, argon can not be generated on demand. Instead it is supplied in cylinders and is typically more expensive than food grade nitrogen due to significantly higher scarcity.
CO2 is also popular for MAP use and it shares the same odourless and tasteless qualities as argon and nitrogen. Although it inhibits oxidation and most aerobic growth, it can result in food turning sour if the volume of CO2 used is too high. It is also easier for carbon dioxide to diffuse through packaging films than it is for argon and nitrogen. Moreover, carbon dioxide can also be absorbed by the food which can result in packaging collapse. In some instances, this can be desirable e.g. for hard cheeses, but in the majority of cases this is something to be avoided.
Another odourless and tasteless gas, carbon monoxide is used similarly to oxygen – to retain the red colour of meat. However, its use for modified atmosphere for food is prohibited in the EU and many other countries, so it is uncommon to find it used in MAP nowadays.
When food is packaged using MAP, this has to be detailed on the label. In line with EU Regulation 95/2/EC the MAP gases used should ideally be listed as their corresponding E number (list below, excluding carbon monoxide). However, manufacturers also have the option to just state on the ingredients list, that the product has been ‘Packaged in a protective atmosphere’.
Oxygen: E 948
Nitrogen: E 941
Argon: E 938
Carbon Dioxide: E 290
If you are considering using MAP but are unsure which gas would be best for your application, contact us today to discuss your requirements with our MAP specialist.
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