Breakdown of intramuscular connective tissue in cod (Gadus morhua L.) and spotted wolffish (Anarhichas minor O.) related to gaping

The purpose of this work was to compare the microstructure of muscle connective tissue in cod and wolffish and to study its degradation during ice-storage to determine which structural alterations are related to the gaping phenomenon. Gaping is very often found in fillets of codfish, but not in wolffish. The results showed that detachments between myofibres occurred prior to the myotomes to myocommata detachments, which occurred more rapidly and to a larger extent in cod than in wolffish. Changes at the ultrastructural level in myocommata proper were mainly related to gaps between collagen fibres and between collagen fibres and cells in the extracellular matrix (ECM). The mean collagen fibre diameter was smaller and the collagen network in myocommata proper was denser in wolffish than in cod. After 7 days of ice-storage the collagen fibres, particular in cod, appeared sparsely packed. The results implied that the increased gaping during ice-storage might be due to degradation of proteoglycans and glycoproteins, important for the spatial organization of the collagen fibres and in anchoring cells in the ECM to the collagen network. (c) 2005 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.