Storage of lipids in the myosepta of Atlantic salmon (Salmo salar)

Storage of lipids in the myosepta of Atlantic salmon (Salmo salar) was determined by dissection of myosepta from both white and dark muscle, by analyzing lipid classes of myosepta, and by analysis of muscle tissues with and without myosepta. By using Iatroscan-TLC/FID it was found that triglyceride was the only major lipid class present in the myosepta. In a sample pooled from three fish, 39.1% of white muscle lipids were found to be stored in the associated myosepta. In the dark muscle up to 62.4% of the total lipids were located in the associated myosepta.After removal of the myosepta, the ratio of the total lipid content of dark muscle to white muscle decreased from 5.25 to 3.66. The proportion of polar lipids increased in both white muscle and dark muscle after removal of the myosepta; however the ratio of phosphatidyl choline (PC) to phosphatidyl ethanolamine (PE) in both muscle types remained constant. This suggests that neutral lipids accounted for most of the lipids in the myosepta. It is concluded that this type of connective tissue, not the actual muscle fibres, stores most of the muscle lipids in Atlantic salmon.