title: Soft texture of atlantic salmon fillets is associated with glycogen accumulation.
abstract: Atlantic salmon (Salmo salar L.) with soft fillets are not suited for manufacturing high quality products. Therefore fillets with insufficient firmness are downgraded, leading to severe economic losses to the farming and processing industries. In the current study, morphological characteristics of salmon fillets ranging from soft to hard were analysed. Different microscopic techniques were applied, including novel methods in this field of research: morphometric image analysis, periodic acid Schiff staining, immunofluorescence microscopy, transmission electron microscopy and fourier transform infrared microscopy. The results showed that the myocytes of soft muscle had detached cells with mitochondrial dysfunctions, large glycogen aggregates and enlarged inter cellular areas, void of extracellular matrix proteins, including lower amounts of sulfated glycoproteins. Myofibre-myofibre detachment and disappearance of the endomysium in soft muscles coincided with deterioration of important connective tissue constituents such as Collagen type I (Col I), Perlecan and Aggrecan. In summary our investigations show for the first time an association between soft flesh of Atlantic salmon and massive intracellular glycogen accumulation coinciding with degenerated mitochondria, myocyte detachment and altered extracellular matrix protein distribution. The results are important for further understanding the etiology of soft salmon.
authors.affiliation: Nofima AS, Ås, Norway.
authors.forename: Jacob S
authors.initials: JS
authors.lastname: Torgersen
authors.affiliation: Institute of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Oslo, Norway.
authors.forename: Erling Olaf
authors.initials: EO
authors.lastname: Koppang
authors.affiliation: Institute of Marine Research, Bergen, Norway.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Stien
authors.affiliation: Nofima AS, Ås, Norway ; Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Ås, Norway.
authors.forename: Achim
authors.initials: A
authors.lastname: Kohler
authors.affiliation: Nofima AS, Ås, Norway.
authors.forename: Mona E
authors.initials: ME
authors.lastname: Pedersen
authors.affiliation: Nofima AS, Ås, Norway.
authors.forename: Turid
authors.initials: T
authors.lastname: Mørkøre
mesh_terms: D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D017756:Aquaculture; D024042:Collagen Type I / Q000378:metabolism; D003238:Connective Tissue / Q000033:anatomy & histology; D005455:Fluorescent Antibody Technique; D006003:Glycogen / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism; D008460:Meat; D032342:Muscle Cells / Q000166:cytology / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000378:metabolism* / Q000648:ultrastructure; D025341:Principal Component Analysis; D012044:Regression Analysis; D020317:Salmo salar / Q000033:anatomy & histology*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D053674:Aggrecans; D024042:Collagen Type I; D019812:Heparan Sulfate Proteoglycans; C071927:perlecan; D006003:Glycogen