MAP can be optimised by maximising the amount of dissolved CO2 in the fish product. This is important because only dissolved CO2 can inhibit the growth of bacteria. Factors that affect this are gas mixture and partial pressure of CO2, the ratio between gas volume and product volume (g/p ratio), pH, chemical composition of the fish product, microbiology and storage temperature.
Increasing the g/p ratio will lead to more CO2 being dissolved in the product. But at the same time, increasing the g/p ratio will lead to transporting a lot of gas and a smaller amount of the product. To resolve this problem, Nofima Mat has developed a CO2 emitter that produces CO2 gas after the pack is sealed. This functions as a humidity absorber and is activated by the loss of liquid from the fish during storage. In this way the CO2 emitter can increase the partial pressure of CO2 in the pack with the use of a smaller volume of gas (g/p 1:2) without any loss of quality or shelf life.
