Modified atmosphere and vacuum packaging of food
How it works
Food in modified atmosphere packaging (MAP) is surrounded with gases that slow down food spoilage by:
- reducing the speed of chemical reactions in the food
- stopping or slowing the growth of bacteria, yeasts and moulds.
With a few exceptions, MAP foods are supposed to be stored in a fridge and can be kept for longer. Some foods, such as cured meats, cheeses and seafood, have all air completely removed from the package – this is called vacuum packaging.
Foods that are sometimes packaged using MAP:
- leafy salads
- fresh pasta
- raw meat
- deli meats
- bakery products (like sandwiches).
Why you should be careful with MAP
Although MAP slows down the growth of microorganisms, it doesn't mean they're not in the food. However, with fewer signs of spoilage and decay – such as mould, 'off' smells or discolouration – it may be harder for you to tell that the food is unsafe to eat.
Read the label
Follow storage instructions to keep safe. Most fresh and minimally-processed foods that are packaged using MAP still require refrigeration.
If you keep the food as instructed on the label, it will be safe to eat until the use-by date. Producers are required to formulate a gas mixture and packaging system that keeps the product both appealing and safe.
There may be separate instructions to follow before and after the package is opened so read carefully.
MAP meat can sometimes be discoloured
Fresh meat appears red because of the way its natural pigments (myoglobin) interact with oxygen. When meat is packaged using MAP, there are low levels of oxygen and there may be high levels of carbon dioxide. This makes the meat turn a purple-red colour which is not desirable but is still safe to eat. The bright red colour returns quickly when the package is opened.
Carbon monoxide has the opposite effect and can make meat appear red even when it's old. For this reason, some countries have banned or limited its use in meat packaging. New Zealand allows only small concentrations ( less than 1%) of carbon monoxide in the packaging of some meats.
Who to contact
If you have questions about food safety, email firstname.lastname@example.org.