Post-mortem structural characteristics and water-holding capacity in Atlantic halibut muscle

Summary

Structural characteristics of seven farmed and wild Atlantic halibut muscle (5 days post mortem) were individually studied, in relation to the pH and water-holding capacity (WHC) of the muscle. Both light- and electron-microscopic techniques were used to qualitatively investigate structural attributes that influence WHC. Farmed and wild halibut with different muscle pH and similar WHC were compared as well as farmed samples having similar pH but different WHC and vice versa. Both farmed and wild halibut exhibited the same structural alterations post mortem but they appeared more pronounced in the farmed fish. Small, new fibres were seen more often in the farmed fish than in the wild fish muscle. Common structural characteristics that could be related to decreased WHC were detachment of sarcolemma, gaps in the extracellular matrix, increased intermyofibrillar space and transverse shrinkage of the cells. It was not evident whether disruptions of the myofilaments influenced the WHC or not. The results indicated, however, that low pH in combination with pronounced structural degradation influenced the WHC more than low pH in combination with minor structural degradation.