– Two days is really a very long time for vacuum packages, which are used everywhere. We have used cod in our research because it is a more difficult perishable product than salmon, says scientist Anlaug Ådland Hansen in Nofima. Photo: Jon-Are Berg-Jacobsen/Nofima

Extends shelf life by two to four days

An ingenious little pad that gently emits extra CO2, can extend the shelf life of a package of fresh cod by more than half a week. A total of four extra days!

– This can have a major impact on reducing food waste, believes Anlaug Ådland Hansen, a scientist at Nofima.


The flat and small stroke of genius is called a CO2-emitter. Nofima has developed this itself with funding from, among others, the Research Council of Norway.

Already today you can find a small pad under the food in all packaging of perishable food which absorbs moisture. And absorb moisture is all it does, but by replacing the small moisture absorber with a CO2 emitter one achieves, at the same time, a longer shelf life. When moisture from the food comes into contact with the emitter, it emits CO2. This inhibits bacterial growth so that the sell by date can be extended

– Today, there are essentially two different packages for perishable foods. One is the vacuum package, where all the air is removed. This makes the storage climate anaerobic. The other type of package is called Modified atmosphere packaging, abbreviated to MAP. Here, the air around the product is replaced with a packaging gas. The most common packaging gas is a mixture of CO2 (carbon dioxide) and nitrogen, Ådland Hansen explains.

Extended shelf life

Tests carried out by Nofima show that the shelf life of a vacuum-packaged cod fillet can be seven days. If you include a CO2 emitter you increase the vacuum packages shelf life to nine days. In other words by two whole days.
Normal shelf life for the same cod fillet in a MAP is up to nine days. If you include a CO2 emitter you extend the shelf life to 13 days! That is, up to four full days longer. The tests with cod and a CO2 emitter were carried out at a temperature of 20 C.

– A CO2 emitter acts as an inhibiter of bacterial growth. So long as you supply enough CO2 you prevent the growth of bacteria in the product, the scientist explains.
However, you can’t just throw in any CO2 emitter. It must release the proper amount of gas to optimise shelf life.

Precision is called for

– The CO2-emitter must be precisely matched to the product, the product’s moisture content and its weight. Likewise, it is important that product hygiene before packaging is properly taken care of, says the scientist. Painstaking precision is, in other words, essential if one is to extend shelf life.

Work on the CO2-emitter has been going on for a decade, and Nofima has every reason to be pleased with the results.

– Two days is really a very long time for vacuum packages, which are used everywhere. We have used cod in our research because it is a more difficult perishable product than salmon. When packaging fresh cod it is particularly important to use a CO2 emitter, says the scientist. This is also the first time a CO2 emitter has been tested in vacuum packages of cod.

Easy to use

Ådland Hansen is satisfied that the solution is so simple for the industry to implement. She also emphasises that the CO2 emitter does not contain anything that does not already exist or is absorbed in the food. It only maintains the gas pressure in the package so that the contents stay fresh longer.
– CO2 emitters are a fairly new technology, but as a modest start they are already used in shops today. Our research shows that they can be given a very extensive application, says Nofima’s Anlaug Ådland Hansen.

Food safety and quality