Nofima scientists are hoping to find out when trawl captured cod should be slaughtered in order to obtain the whitest fillet and best texture.
The trial involved placing 87 cod in the experimental swim tunnel at the Tromsø Aquaculture Research Station. During a 15-minute period the velocity of the water current was increased from low to high, and the fish were removed as they became exhausted.
“The objective is to get as many fish exhausted at the same time so the situation will be as similar to real trawling as possible. The exhausted cod are placed in cages submerged in a tank, where they are divided into five different groups, which recuperate for zero, two, four, six and 10 hours respectively. The first group is slaughtered immediately without any recuperation time,” says Ragnhild Aven Svalheim, Research Fellow at Nofima, who is managing the trial.
The scientists are attempting to find out the ideal recuperation time in order to optimise the muscle quality of the cod in respect to both colour and texture.
Test so far found that fish which recuperate for three hours prior to slaughter have a lot of blood in their musculature, and the meat becomes red and not as appetizing for the consumer.
After all the groups of cod were slaughtered, the scientists took blood tests and a series of other tests were performed.
The cod are stored on ice and the rigor mortis is measured at regular intervals for 72 hours.
The scientists at Nofima hope that this trial will enable them to find out as much as possible about the optimisation of trawl capture of white fish in order to raise the quality of the fish, both physically and visually.
