Post-mortem calorimetric and biochemical profiles of Chinook salmon (Oncorhynchus tshawytscha) white muscle following rested and exhausted harvesting

We report calorimetric and biochemical profiles of anoxic, post-mortem, white muscle from Chinook salmon subjected to rested and exhausted harvesting regimens. Heat output was greater (P < 0.01) in the rested group immediately after death (ca. 400 mu Wg(-1)), and for the first 7h post-mortem, reaching a nadir of about 15 mu Wg(-1) by 12 h. In exhausted animals, heat output was relatively unchanged at <10 mu Mg-1 over 24 h. In both groups there was an exothermic event, occurring between 4 and 6 h post-mortem, amounting to a rise of ca. 35 mu Wg(-1). The greater heat production by the muscle from rested animals was accompanied by elevated pH (7.5 vs 6.7, P<0.05), and higher concentrations of glycogen (16 vs 2 mu mol g(-1)), creatine phosphate (18 vs 0.1 mu mol g(-1)), ATP (6 vs 3.5 mu mol g(-1)) and potential energy (30 vs 7 mu mol g(-1)) than the exhausted group, which had elevated concentrations of lactate (43 vs 18 mu mol g(-1), P<0.05) and glucose (5 vs 2 mu mol g(-1)), over a number of hours post-mortem. The maintenance of potential energy in the form of ATP, glycogen and creatine phosphate for an extended period post-mortem indicates that tissue viability is extended in muscle from fish that are harvested in a rested manner. (C) 2009 Elsevier B.V. All rights reserved.