the norwegian institute of food, fishery and aquaculture, established a packaging technique that allows salmon to stay fresh for up to 20 days.superfresh is a technology to package salmon under vacuum, after placing a co2 emitting cushion that consists of, among others, citric acid and baking powder, in the packaging.after the pack is sealed, the cushion develops co2 gas and it also has absorbent properties.this co2 emitter has been adapted for the product, so that it does not change the fish&rsquos ph value, and sensory tests have also shown that the fish often has a higher quality than with comparable packaging technologies.this way salmon can be kept fresh for up to 20 days at a consistently low temperature, or between 10 and 12 days at 4°c.