Objective  Effects of vitamin C addition in water to improve cold-tolerance of turbot ( Scophthalmus maximus ) on the physiology, biochemistry, and muscles of the fish in chilling preservation were studied.

  Method  Live turbots were kept in water containing 0, 25, 50, or 100 mg·L⁻¹ of vitamin C for 12 h prior to chilling to 3 ℃ by circulating the water through a refrigeration system and holding for 0, 12, 24, 36, 48, 60, or 72 h out of water to observe the survival rate of the fish and determine the optimal vitamin C concentration for the pretreatment. In water with the optimized vitamin C concentration, turbots were kept for 12 h followed by cooling the water to 18, 13, 8, and 3 ℃ to measure the physiological and biochemical indexes, such as white blood cells, epinephrine, cortisol, and muscle texture, of the turbots under cold stress.

  Result  The turbots kept in water containing 50 mg·L⁻¹ vitamin C then chilled to 3 ℃ for 72 h had the highest survival rate at 40.0%. The white blood cells, red blood cells, hemoglobin, and platelets of the vitamin C-treated fish were significantly higher than those of control (P＜0.05). During cooling from 18 ℃ to 3 ℃, the contents of serum epinephrine, cortisol, and total protein in fish were on an increasing trend, while serum glucose, liver glycogen, and muscle pH decreasing; the physiological and biochemical indexes changed significantly less on the pretreated turbots than control (P＜0.05); and the muscle firmness, elasticity, and chewiness of the treatment fish were significantly higher than those of control (P＜0.05).

  Conclusion  With a 50 mg·L⁻¹ vitamin C pretreatment, the negative impacts of cold stress on liver and kidney of the chilled turbots were significantly reduced and the energy metabolism and meat quality of the fish relatively unaffected.