Pre-rigor filleting and drip loss from fillets of farmed Atlantic cod (Gadus morhua L.)

Improved slaughtering procedures of farmed fish may provide sufficient time so that filleting can be performed pre-rigor while the muscle pH is still high. Such filleting not only reduces fillet gaping but also lowers the transportation costs and makes fresh fillets available to the markets at an earlier stage. The aim of our work was to determine the weight reduction of the fillets due to liquid loss and to study the proteins and enzymes in the drip. After 11 days of cold storage, fillets of farmed Atlantic cod produced pre-rigor had a weight loss of 10% and a fillet contraction of 19% while for fillets produced post-rigor the values were 5% and 4% respectively. At the same time, approximately twice the amount of proteins had been lost from the pre-rigor-produced fillets. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis showed that the proteins in the drip were similar to the sarcoplasmatic proteins extracted from the muscle. Specific analysis of proteolytic enzymes indicated that they are less stable in the expelled liquid than in the flesh during storage. The extensive loss of weight and proteins from pre-rigor-produced fillets during subsequent storage must be taken into account if such processing is considered for farmed cod.