Stunning/slaughtering by cold shock in saline water: Effects on fish stress, post-mortem changes, and product quality in rainbow trout

This study evaluated the effects of two stunning/slaughtering methods, percussion vs. immersion in cold saline (−6 °C, 5% NaCl) water, on stress status and freshness evolution in rainbow trout (Oncorhynchus mykiss). Stress indicators (cortisol, malondialdehyde-MDA) were measured in plasma, muscle, fin and skin mucus of 30 fish (15 per treatment), while freshness evolution and quality (pH, rigor mortis index, fillet and skin colour, and muscle texture) were assessed in 70 fish (whole fish and fillets; 35 per treatment) at 3, 48, 168, and 264 h of storage.