Influence of the interposition of pink muscle fibers in the dorsal ordinary muscle on the post-mortem hardness of meat in various fishes.

We previously showed that the tenderization of ordinary muscle during ice storage is affected by the interposition of pink muscle fibers in the ordinary muscle. However, little is known about whether or not the interposition of pink muscle fibers affects the hardness of raw fish meat. To clarify the influence of the interposition of pink muscle fibers in the dorsal ordinary muscle on hardness of meat, the breaking strengths and the fiber types of the dorsal ordinary muscle of eight fish species (a total of thirty-seven specimens) were discriminated. The breaking strengths among fish species were within a range of 6.5 N/cm2 to 19.1 N/cm2 . Pink muscle fibers were found in the dorsal ordinary muscle of six out of the eight fish species ranging from 0.0% to 56.0% in quantity ratio, and 0.0% to 19.3% in area ratio, respectively. The quantity ratio and area ratio of pink muscle fibers in the dorsal ordinary muscles of all eight fish species samples positively correlated with the breaking strength. Relative to the quantity ratio (p < 0.05), the area ratio (p < 0.02) of pink muscle fibers was more representative of post-mortem texture hardness. In conclusion, the high interposition ratio of pink muscle fibers in ordinary muscle could potentially improve the post-mortem hardness, the texture, and even the flesh quality of raw fish meat.