Fish and seafood products consist of an enormous variety of species. On the international market ground fish, pelagic and fresh water fish, shellfish and other molluscs or crustaceans are imported and exported from one country to another. These products are brought to the market in a variety of forms and conditions such as “fresh whole”, frozen (whole or in parts), dried, pickled or salted and cuts (such as in the form of fillets or steaks), as well as “live”.
Facts about Seafood
Seafood and fish are highly perishable products. From the moment they are taken from their natural environment and until made ready for consumption handling methods and temperature, which are critical points, must be extremely controlled.
The particularly soft muscle structure of fish makes it susceptible to physical damage and highly sensitive to temperature fluctuations. Such products, which are subject to temperature increases, will soon show evident signs of a decrease in quality.
It is crucial to keep the temperature as low as possible throughout the handling chain. At harvest fish and seafood are chilled at 0°C in ice or submerged in -2°C seawater. From that point onwards, the temperature for any kind of fresh fish and seafood must be kept between -1°C to 1°C, in order to optimize their shelf life. For frozen products, the ideal temperature to preserve the products is under -23°C.
When the cold chain has failed, meaning that temperature ranges have not been properly maintained, fish and seafood will then be susceptible to many types of degradation. This in turn will have a direct impact on the product quality. When stored and kept within optimal temperatures, fresh fish and seafood have a shelf life that can vary between 4 to 18 days.
Examples of Some Categories of Fish and Seafood:
| GROUND FISH | PELAGIC FISH | FRESH WATER FISH | SHELL FISH AND MOLUSKS |
| Cod Dogfish Flatfish Haddock Hake Halibut Lingcod Monkfish Perch Plaice Pollock Sablefish Sole Turbot |
Alewife Anchovy Capelan Eel Herring Mackerel Salmon Sardine Sea Bass Shark Tuna (Alba-core, Ship-jack, Bonito, Yellowfin) |
Trout Carp Tilapia Salmonidae, nes |
Crab Clam Cuttlefish Geoduck Lobster Mussel Oyster Octopus Scallop Sea Urchin Shrimp Squid Snails |
Temperature abuse or inappropriate handling will irrevocably lead to a rapid deterioration of the product. Bacterial activity grows rapidly on the surface and inside the product as the temperature increases, thereby digesting the flesh and producing acids that destroy texture and produce off-odour. The enzymatic activity, which is necessary during living activities, will by consuming the flesh cause objectionable texture changes after death and become problematic. This problem will be compounded at temperatures higher than 5°C.
The following chart shows the characteristics of a good fish compared to an off-condition fish:
| ANATOMY PARTS | GOOD CONDITION | OFF-CONDITION | |
| Skin | General | Bright appearance | Dull, lifeless appearance |
| Colour unfaded | Faded colour | ||
| Shiny | Dry and cracked | ||
| Characteristic odor | Off-odor | ||
| Scales | No missing scales | Many missing scales | |
| Slime | Natural creamy white or transparent covering fish | Yellowish slime with bad odor | |
| Dry, milky appearance of slime | |||
| Eyes | Clear, bright | Dull | |
| Slightly protruding bulging | Sunken | ||
| Full prominent | Dissappearing | ||
| Gills | Pink to dark | Dirty colour | |
| Bright in colour | Very pale pink or dark brown. Gray or grayish | ||
| No off-odor | Slimy, foul odor | ||
| Abdomen | Clean | Discoloured | |
| Free from offensive odor | Foul odor, offensive, soft and pulpy | ||
| Interior of the body cavity becomes reddened | |||
| Flesh | Firm to the touch | Soft and limp | |
| Firmly attached to the bones | Flesh is no longer firmly attached to bones | ||
| Pits readily on pressure | |||
| Dull, yellowish/ brownish cast to the flesh | |||
| Napes and Belly | Napes and belly walls are firm and elastic | Napes and belly walls are soft and pulpy | |
| Depression will not remain when finger is removed | Inside surface has been turned to a brownish colour | ||
| Tainted odor | |||
| Backbone | Pearly gray colour | Pink discolouration | |
| Odor | Mild | Tainted, strong | |
| Sea-water odor | Rank odor | ||
| No foreign odor | Putrid or Rotten | ||
| Contamination | Free from parasite | Free from parasite | |