Antemortem and postmortem biochemistry, drip loss and lipid oxidation of European sea bass muscle tissue

Abstract

Slaughtering methods of farmed fish can influence swimming activity and stress levels with consequences for the flesh quality properties of fish fillets. For example, muscle metabolic activity prior to death can affect the concentration of oxygen, ATP and the pH of muscle. Handling stress of fish prior to harvesting is characterized by increased swimming activity which leads to anaerobic metabolism while energy stores are depleted and white muscle pH drops leading to acceleration of autolytic reactions after death with consequences for the organoleptic parameters of fish fillets and the filleting yield of farmed fish. In addition to the food quality aspects of the slaughtering method, the potential suffering of fish being handled during common aquaculture procedures or during slaughtering prompted scientific research in the welfare of farmed fish during harvesting. The purpose of this work was to investigate the effect of handing stress on post- mortem muscle pH and rigor mortis. European sea bass were harvested using two different levels of handling stress. Muscle pH was monitored shortly after death and after ice storage. Drip loss, and thiobarbituric acid reactive substances (TBARS) were measured in ice stored fillets. Antemortem stress resulted in rapid drop of muscle pH and onset of rigor mortis. Drip loss, and thiobarbituric acid reactive substances (TBARS) increased in the stressed fish. The results indicate that reducing handling stress during harvesting can delay rigor mortis and improve the quality of European sea bass fillets.