Interactions between ice storage time, collagen composition, gaping and textural properties in farmed salmon muscle harvested at different times of the year Marit Espe a, * , Kari Ruohonen b , Marit Bjørnevik c,1 , Livar Frøyland a , Ragnar Nortvedt a , Anders Kiessling c,2 a National Institute of Nutrition and Seafood Research, NIFES, P.O. Box 176 Sentrum, N-5804 Bergen, Norway b Finnish Game and Fisheries Research Institute, Turku Game and Fisheries Research, Ita ¨inen Pitka ¨katu 3, 20520 Turku, Finland c Institute of Marine Research, Matre Aquaculture Research Station N-5984 Matredal, Norway Received 24 June 2003; received in revised form 31 March 2004; accepted 19 April 2004 Abstract Atlantic salmon were sampled in June, September and February of the consecutive year and were stored on ice for up to 14 days in order to test the effect of harvest time and subsequent ice storage on meat quality. Texture and gaping frequency were analysed and were related to colour, protein degradation, collagen solubility, collagen types and final pH as well as lipid oxidation in the fillets to test possible interactions between harvest time and quality degradation during storage. In February, the connective tissue contained more soluble collagen and less insoluble collagen, as well as more of both types I and V collagen, than in the samples collected in June. During ice storage, fish became softer with a concomitant increase in the number of fish displaying very high gaping. pH increased during ice storage and fillet colour became lighter and redder, while yellowness changed in the fattier fillets upon ice storage. Ice storage resulted in changes in pepsin-soluble collagen (PSC) depending on harvest time as did both types I and V 0044-8486/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2004.04.023 * Corresponding author. Tel.: +47-55905143; fax: +47-55905299. E-mail address: marit.espe@nifes.no (M. Espe). 1 Present address: Bodø College, N-8049 Bodø, Norway. 2 Present address: Department of Animal and Aquacultural Sciences, Agricultural University of Norway, P.O. Box 5003, N-1432 Aas, Norway. www.elsevier.com/locate/aqua-online Aquaculture 240 (2004) 489 – 504