Biochemical, physical and sensory quality of ice-stored Atlantic cod (Gadus morhua) as affected by pre-slaughter stress, percussion stunning and AQUI-S™ anaesthesia

Biochemical, physical and sensory quality of farmed Atlantic cod subjected to percussion stunning (control), anaesthesia (AQUI-S™) and excessive exercise (30 min chasing before slaughter, ‘stressed’) were analysed after 7 days of ice storage. The white muscle energy status (initial pH, muscle twitches and high-energy phosphates) revealed that the fish were truly representatives of rested (percussion stunned and anaesthetised) and stressed cod. Sensory evaluation showed that the fillets of cod exposed to percussion stunning and AQUI-S™ anaesthesia prior slaughter had slightly higher whiteness scores, and that the fillets of AQUI-S™ anaesthetised cod had slightly shinier surfaces than the fillets of cod exposed to pre-slaughter stress. Furthermore, fillets of anaesthetised (AQUI-S™) cod had significantly higher inosine monophosphate (IMP) contents and lower K-values than fillets of cod exposed to pre-slaughter stress, after 7 days of ice storage. Pre-slaughter stress did to some extent affect fillet colour immediately after killing and after ice storage. Otherwise, no significant effects of stress were observed with regard to biochemical, physical or sensory quality (ultimate pH, water content, drip loss, water holding capacity, texture and gaping) of farmed Atlantic cod.