- The freezer must be at least minus 30° centigrade before the freezing begins
- Fish will be damaged if left too long in the freezer
- The fish must be thoroughly frozen before being removed from the freezer
All species of fish except mackerel, herring, red fish, spiny dogfish and sea trout must be gutted.
The gutting can be done manually or mechanically. The gutting cut can vary by species.
The gutting cut should be done mid-belly, between the pelvic fins in an even cut towards the anal vent. Coley, haddock, common ling and tusk should be cut to the left of the anal fin and all the way back to the abdominal cavity.
Gutting of roe-bearing fish and large fish
When gutting large fish and roe-bearing fish, it can be an advantage that the gutting cut does not open the whole belly. When the cut starts at the pelvic fins, the collar bones remain connected, and it is easier to handle the fish without causing damage.
If the fish liver and roe is to be preserved, it is important to cut in carefully aslant from below the belly. Use a knife with a rounded point to avoid damaging the roe sac and the liver. Cut the intestine at the throat and remove the entrails carefully from the abdominal cavity.
We will here demonstrate bleeding and gutting of halibut in one operation.
The gutting cut should be done on the lighter side of the fish, to make it easier to see if the cut has been performed correctly. It is not wrong to cut on the darker side, but it makes it more difficult to check where you cut. Begin your cut from the upper edge of the gill cover, right behind the pectoral fin and cut down towards the anal vent.
If the flatfish is to be sold with the head, remove the entrails and gills.
The blood along the back bone of halibut and Greenland halibut must be removed. It can be scraped off with a spoon.
At the front of the neck of the halibut and the Greenland halibut there are two glands which can discolour the flesh of the fish, and must therefore be removed.
To remove blood in the veins of halibut, the rear of the abdominal cavity can be washed out with water. This results in an effective removal of the blood.
Incorrect gutting cuts
Gutting the fish incorrectly can reduce profitability, and even completely ruin the fish. If the gutting cut opens the fish flesh, the fish will be exposed to bacterial growth and bleeding in the flesh.
Poorly gutted fish will darken in colour and deteriorate in quality during storage. All the liver must be removed to avoid the fish flesh growing rancid. This results in a yellowish colour and an unpleasant taste. If the gall bladder is punctured, there will be green discoloration of the flesh.
We will now demonstrate the consequences for the quality and appearance of the fish of incorrect gutting and cleaning. This is a poorly cleaned cod with traces of liver and blood. After 14 days in cold storage the liver traces have resulted in yellow spots in the flesh and the blood has caused dark spots in the belly. The damage is even more visible in the filet. The discoloration in the abdominal cavity has been transferred to the filet.
The following points are important when gutting:
It is important that the head is cut correctly with nice and clean cuts. If the head is cut incorrectly with loose collar bones and ruined necks, it results in poor quality or even in the fish being ruined.
The decapitation can be done manually or mechanically. There are several methods of cutting.
Round cut: cut through the throat and the upper intestine. Avoid harming the collar bones. Cut through the cartilage between the neck vertebrae and press the head backwards while cutting. The head is to be cut with a crescent-shaped cut, without tearing it off.
The round cut is used when the fish is to be used when the fish is to be salted, salted and dried, or just dried (stockfish).
Straight cut: remove the head in one continuous cut.
The straight cut can be used when the fish is to be filleted or sold as whole, fresh cod.
You can clearly see the difference between round cut and straight cut here.
Japanese cut: In a Japanese cut, one cuts from the neck diagonally behind the collar bones and pectoral fins down towards the anal vent. Cut as close to the collarbone as possible. Do not cut all the way to the anal vent, one to two centimeters of the abdominal cavity is supposed to remain.
Icelandic halibut and red fish is often Japanese cut.
The following points are important when cutting:
When cutting cod, it is important to be aware of the post-clavicle bone. It is attached to the collarbone and goes diagonally into the filet. If you handle the fish too roughly, the post-clavicle bone can cut into the flesh and cause bleeding.
Packaging, labeling and frozen storage.
The fish must be packaged correctly to ensure good protection of the product. Sorting and labeling depends on customer requirements and quality regulations.
The following points are important:
Four examples of fish with quality errorsWe will here illustrate the difference between fish with quality errors and of good quality.