Understanding factors affecting flesh quality in farmed fish

This chapter discusses the factors affecting the quality of the fish muscle, focusing on nutrient composition, harvesting methods, and changes occurring during the rigor mortis process affecting flesh quality. Some fish species show seasonal changes in muscle lipid content and then the lipid content is exchanged with water, keeping the other nutrients more or less constant. Farmed fish are fed numerous variations in diet energy density, are subjected to changes in feeding rate, manipulations of the dietary compositions, and light regimes resulting in changed breeding season, all factors that might influence the nutritional and sensory quality of the fish flesh at harvest. Product tailoring is focused on production of fish meat that is to contain a pre-defined nutritional composition when harvested. Lipid rich farmed fish like the salmonids are relatively easy to tailor when it comes to lipid soluble nutrients, but much harder when considering the water soluble nutrients. The fact that protein composition in fish is determined by the genetic code and the fact that free amino acids cannot be stored as such, which means that the fillet protein cannot be tailored. A high flesh quality might be defined as a fish muscle containing nutrients that are health promoting for the consumer, and have the texture and taste required by consumers but concomitantly containing as little as possible of any harmful contaminants that might jeopardize human health. Further, processing and slaughter methods might affect the final quality of the harvested fish.