Most Norwegian salt-cured fish today is produced from headed cod that is stored chilled or frozen. Prolonged chilling of headed fish is believed to cause discolouration in the neck region.
This project has documented to what extent chilling head-on or head-off can result in a different quality and yield of salt-cured fish and clipfish.
The trial involved several different chilling methods and storage times. Regardless of the chilling method, fish stored head-off had more discolouration in the neck than raw material stored head-on. However, somewhat more discolouration was detected when ice-water was used rather than storing the fish on ice in crates.
The degree of discolouration increased with increased salt and storage time. Naturally enough, the exposed neck region of stored fish had the most discolouration, but the trial also demonstrated that headed fish salted on the date of catch developed some discolouration. An equivalent connection of discolouration was not found in the actual fillet, regardless of chilling method and storage time.
The weight of fish stored head-on in ice-water increased. The reason for this increase is that water gathers in the gills and head, thereby increasing the weight. When the fish was stored on ice in crates, the weight remained stable or decreased slightly, regardless of whether the fish was headed or not.
Head-on or head-off, the product yield was the same if other conditions were equal. However, the trial pointed to the fact that storing the raw material before salting has a significant impact on the product yield. Fresh cod that was salted on the date of catch produced significantly less yield than cod stored for instance for seven days prior to salting, regardless of the chilling method.
The project 'Discolouration of salted-cured fish and clipfish (cod) when the raw material is stored head-on and head-off' is financed by the Fishery and Aquaculture Industry Research Fund (FHF).