Stunning, pre slaughter and filleting conditions of Atlantic salmon and subsequent effect on flesh quality on fresh and smoked fillets

The aim of this study was to investigate how stunning methods in combination with pre slaughter conditions such as pumping and live chilling influence the flesh quality in both fresh and smoked products of Atlantic salmon (Salmo salar). For quality measurements, a total of 181 fish were percussive stunned at the 1) cage, 2) after pumping and 3) after live chilling, where half of the fish were stimulated with 16 s of electricity in order to simulate electrical stunning. Muscle pH and rigor index were measured for 4 days in 10 fish from each group (n = 60). The other 121 fish were either pre (n = 57) or post rigor filleted (n = 64). After 7 days on ice storage one fillets from each fish was analyzed for gaping, color, drip loss, and texture hardness, while the other fillet was dry salted and smoked and evaluated 14 days post mortem. Muscle pH and time to onset of rigor decreased according to the number of events (pumping, live chilling and electrical stunning). For fresh fillets the filleting method was the predominant factor for the end quality overshadowing the influence of pre slaughter conditions and stunning method. Salting and smoking eliminated differences caused by slaughter or filleting methods. We conclude that the quality of Atlantic salmon is influenced in following order: stunning method < pre slaughter conditions < filleting method < processing by salting and smoking.