Involvement of Type V Collagen in Softening of Fish Muscle during Short-Term Chilled Storage

Type V collagen became solubilized in softened sardine muscle after 1 day of chilled storage with the concomitant weakening of pericellular connective tissue induced by disintegration of thin collagen fibrils. However, no significant changes were observed in the structure of interstitial connective tissue or biochemical properties of type I collagen. Z disk in myofibrils showed structural changes, but no significant loss of longitudinal continuity of myofibrils was observed even at the deteriorated Z disk from the muscle destroyed by compression test. On the other hand, tiger puffer muscle did not show significant softening during the storage, with no significant changes in structure of connective tissues and biochemical properties of collagens. These facts suggest that degradation of type V collagen causes disintegration of the thin collagen fibrils in pericellular connective tissue, weakening pericellular connective tissue and resulting in postharvest softening.