Electrical stimulation of Atlantic salmon muscle and the effect on flesh quality

The duration of an electrical stimulation and subsequent effect on quality was investigated to determine favourable durations for stunning Atlantic salmon (Salmo salar). A total of 78 fish were killed at the cage by a percussive blow to the head where one fillet was used as a control, while the other was stimulated with electricity for 6, 12 or 180 s. Fillets from 16 fish, were placed in a cold room under ip-cameras and pictures were taken every 5 min to measure fillet shrinkage during rigor. The fillets from the 62 other fish were after pH, weight and colour measurements wrapped in aluminum foil and stored on ice. At days 8 and 16 of storage the fillets were taken out for pH, drip loss, water holding capacity (WHC) and texture profile (TPA) measurements. Results show that a prolonged electrical current causes initially the fillet pH to drop, paler fillet colour and increased and accelerated fillet shrinkage compared to control fillets. Fillets exposed for 12 or 180 s of electricity had higher drip loss and lower WHC than their respective control fillets, but not until after 16 days of storage, while colour and TPA remained more or less unaffected by treatment for the entire storage period. We conclude that a 6 s current duration is a favorable duration for stunning fish as pre rigor times and other quality attributes are slightly changed.