We have developed a range of MAPAX® solutions to overcome the challenges facing fish and seafood specialists.
Microbial growth and enzymatic processes lead to rapid loss of original quality in fresh fish and seafood. This is due to their high water activity, neutral pH (where microorganisms thrive) and the presence of enzymes, which rapidly undermine both taste and smell. The breakdown of proteins by microorganisms gives rise to unpleasant odors.
The oxidation of unsaturated fats in oily fish such as salmon, herring and mackerel also results in an unappetizing taste and smell. Fish, such as herring and trout, can turn rancid even before microbial deterioration is detectable.
To maintain the high quality of fresh fish products, it is absolutely essential that the temperature is kept as close to 0°C as possible. Combined with proper temperature control, the right gas mixture can extend the shelf life of fish by a few crucial days – assuming of course, that the refrigeration chain is unbroken.
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Carbon dioxide preserves quality
The presence of carbon dioxide (CO2) has a strong inhibiting effect on common aerobic bacteria such as pseudomonas, acinetobacter and moraxella. At CO2 levels above 20% in sufficiently large package volumes, it does this by lowering the pH of the fish’s tissue surface.
The CO2 concentration is normally 50%. Depending on the storage temperature (0–2°C), Modified Atmosphere Packaging prolongs the shelf life of raw fish packaged in a tray with film wrap, by 3 to 5 days. However, excessively high concentrations can produce undesirable side effects in the form of lost tissue liquid or, in the case of crabs, an acidic or sour taste.
Cod, flounder, plaice, haddock and whiting are examples of fish that can be stored twice as long in a modified atmosphere as in air, at a temperature of 0°C.
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Oxygen preserves color
Oxygen can be used within a modified atmosphere mix to avoid discoloration and pigment fading in fish and seafood. It also prevents the growth of anaerobic microorganisms such as clostridium, which can produce toxins.
When fish is packaged in the correct modified atmosphere, with a short shelf life, the risk of Clostridium growth is negligible. If the temperature is kept below +3°C (+37.4ºF), Clostridium can be prevented from growing at all.
To avoid rancidity, oxygen should not be used to package oily fish – nitrogen is more suitable in this case.
