Distribution, Deposition, and Modelling of Lipid and Long-Chain Polyunsaturated Fatty Acids in Atlantic Salmon Fillets

Abstract This review focuses on an understanding of lipid distribution and deposition dynamics in Atlantic salmon and explores the extent to which these can be predicted through multi-dimensional modeling. The methodology used to measure lipids can have an impact on their assessment and considerable work has been done to standardize and develop robust rapid assessment measures. The distribution of lipids in salmon fillets is spatially variable, with levels consistently highest in the belly region and lowest in the tail section. The level of lipids in the whole-body, fillet and Norwegian Quality Cut (NQC) of Atlantic salmon increases with fish size but plateaus as size increases. Lipid levels are predictable based on fish size data although there are various other factors that influence lipid deposition in the fillet. The relationship between these factors and the deposition of n-3 LC-PUFA is mathematically complex but does lend itself to multidimensional modeling. Effects are strongly influenced by dietary fatty acid composition and for the most part a “parity” exists between levels of certain fatty acids in the diet and what ends up in the body tissues. This parity results in a “dilution effect” that generally explains the relationship between diet and whole-body fatty acid levels. Some specific fatty acids demonstrate traits of selective retention in Atlantic salmon muscle tissue. Notably, docosahexaenoic acid is preferentially retained compared to other fatty acids. Which is explained by the understanding that not all fatty acids dilute at the same rate and biologically active fatty acids, like EPA, are essential for mediating inflammatory responses and have a critical role to play in biosynthesis. There are various influential dietary factors in addition to the level of specific fatty acids in the diet, that affect the level of deposition of n-3 LC-PUFA in the muscle.