Post-mortem softening of fish muscle during chilled storage as affected by bleeding

Bleeding caused the delay of muscle softening in yellowtail, horse mackerel, and striped jack, which are pelagic fish. Conversely, bleeding had no influence on the muscle firmness of red sea bream, flatfish, and rudder-fish, which are demersal fish. Transmission electron microscopy showed delay of degradation of pericellular collagen fibrils in bled yellowtail and horse mackerel. Striped jack showed slower weakening of the pericellular connective tissue in a compression test. However, the demersal fish had no structural difference due to bleeding. These results indicate that removal of blood could delay collagen fibril degradation and muscle softening of pelagic fish.