Change of meat quality in tiger puffer during frozen storage

Quality of frozen tiger puffer meat was evaluated in a comparative study with frozen yellowtail. After being frozen by air blast freezing, the fish samples were stored at -50 degrees C for 1-6 months. Two different methods of thawing were tested; in running water at 17 degrees C and in still air at 4 degrees C. The breaking force of fish meat for yellowtail decreased rapidly over the first month, however, no significant difference was observed for the tiger puffer regardless of freezing duration. The amount of free drip in the yellowtail was relatively low compared that observed in the tiger puffer which increased continually for three months. Histological observations showed less damage in the tiger puffer cells than in the yellowtail, with cell structure prior to thawing in the yellowtail being subjected to significant extracellular freezing, while intracellular freezing occurs in the tiger puffer.