Structural and ultrastructural changes on muscle tissue of sea bass, Dicentrarchus labrax L., after cooking and freezing

In ThR muscle samples the formation of ice crystals during the freezing process produced abundant clear spaces occupied by liquids at the interstitial spaces and inside the muscle fibres. The reciprocal arrangement of thick versus thin contractile filaments was altered in transversal sections, most sarcolemmas were broken and the intermyofibrillar spaces significantly increased. Cooking of thawed muscle samples caused massive protein coagulation and disintegration of myofibrils. The most significant feature in these samples was the appearance of intrafibrillar cavities (holes) within the muscle fibres, which were occupied by liquids, amorphous material and granular aggregates. Also, endomysium was often replaced by a dense “chain like” line of small granular aggregates. Correlation between the structural changes, as described in the present study, and textural and organoleptic characteristics would contribute to define the optimal conditions of postmortem processing of sea bass flesh.