Age of Farmed Atlantic Salmon at Seawater Transfer Affects Muscle Collagen Content and Solubility at Harvest

Salmon released to seawater as different smolt types differed significantly in the total collagen content and the solubility of the collagen present. A 11/2 smolt contained more total collagen than 1/2 and 1 smolt types. Less insoluble collagen and more of the pepsin soluble collagen was generally present in 11/2 smolt type as compared with both 1/2 and 1 types, with the exception of prerigor type 1 salmon. No differences between smolt types in acetic soluble collagen were present. Fish with the higher amount of collagen also had the lowest end pH. Although the bled body weight differed, no correlation between body weight and collagen content or its solubility was found. Fish with higher end pH had lower total collagen and pepsin soluble collagen (r = ‐0.77, P = 0.0001 and r = ‐0.51, P = 0.04, respectively, and more insoluble collagen (r = 0.72, P = 0.002).