Farmed salmon is generally of good quality, but on occasions salmon fillet can be soft. Previous studies indicate that the firmness of the meat is linked to a certain degree to the health condition of the fish.
Arginine and glutamate are natural amino acids that can produce increased muscle growth and health benefits in both humans and animals.
In a feeding trial from a weight of approximately 100 g until to a weight of approximately 3 kg the following year, one group of salmon received feed with the amino acid arginine mixed in, a second group received feed with glutamate mixed in while a third control group received standard feed without protein supplements.
The results show that salmon in the groups that received feed containing protein supplements generally had firmer fillet than the salmon that ate standard feed.
Salmon that had received glutamate supplements maintained a good level of firmness throughout a 12-day storage period, but salmon that had received the standard feed as expected became softer during storage.
A salmon’s liver appears to be a good indicator of the health condition of the fish. As in humans, increased fat content and enlarged liver are signs of being overweight and having disturbed metabolism.
The study pointed to the fact that the salmon that were fed standard feed had the largest liver and highest fat content. These salmon also had elevated values of an enzyme that is often used as a marker for liver damage when compared with the fish that were fed supplements of amino acids.
“This result shows that muscle firmness is influenced by many factors and that the feed appears to play a more important role than previously thought,” says Senior Scientist Turid Mørkøre from Nofima. “The protein composition is of greater significance to the fillet quality and health of the salmon than we initially realised and this is something that we should follow up. These finds provide a basis to more closely study the nutritional requirement in different phases of the life of today’s farmed salmon.”