Soft flesh problems in farmed marine fish

Several factors such as the amount and quality of the feed, harvesting and slaughtering methods, and storage time after slaughter, can affect both technological and sensory properties of the fish fillet. Several factors such as the amount and quality of the feed, harvesting and slaughtering methods, and storage time after slaughter, can affect both technological and sensory properties of the fish fillet. Examples of negative properties that may be found both in wild and farmed fish, are too soft muscle a nd fillet gaping. The softening of the muscle makes it difficult to fillet the fish and the results are low yield and products of inferior sensory quality of reduced value. Marine species like codfish appears to be particular prone to softening and gapi ng. Extensive flesh softening often coupled with pale muscle, has been noticed in products of Atlantic salmon as well. After slaughter, farmed fish show more severe structural alterations including pathological features such as fibre loss and loss of ori ented fibre structures in the muscle tissue, than the wild counterparts. High numbers of inflammatory cells such as lymphocytes and macrophages, and fibroblasts have also been observed in the muscle. It is not known if the increased degradations are due t o changes in physiochemical properties of the muscle or only changes in the amounts of enzymes or inhibitors. Neither is it known if the degradation enzymes are endogenous to the muscle fibres or originate from cells in connective surrounding the muscle f ibres. Our hypothesis is that severe husbandry stress or exhaustion during the slaughtering procedure, may cause influx of inflammatory cells, activation of endogenous systems and cause pathological type of (oxidative) changes which may result in more se vere structural degradation and soft muscle flesh. To better understand these mechanisms we will study proteolytic enzymes (matrix metalloproteinases and cathepsins), enzymatic degradation and peroxidation in muscle of cod. The results from the study may suggest ways through husbandry practice including slaughtering procedures, to reduce the soft flesh problems in farmed fish.