The effect of blood deposition on the degradation of the connective tissue of the yellowtail Seriola quinqueradiata during storage.

Blood is deposited in fish muscle during storage, and this deposition accelerates the deterioration of flesh quality. We have examined the effect of blood deposition on the degradation of collagen fibrils and fibers in the ordinary muscle of yellowtail (Seriola quinqueradiata). In this study we compared changes in collagen fibrils and fibers in the upper sides and undersides of yellowtails killed by two different methods (spinal cord destruction with blood removal and suffocation in air without blood removal [SA]). Tests of breaking strength showed that ordinary muscle from the underside of fish in the SA group (SA-under)had a slightly low value than the other groups. Histological observations showed thinner collagen fibers and looser structures in the SA-under groups than in the other groups during storage. In addition, blood-derived gelatinolytic activities were higher in muscle from the the underside of the SA group than in other groups. These results indicate that blood contains gelatinolytic enzymes and that when blood is deposited to the underside from the upper side of fish, these enzymes may participate in accelerating the degradation of collagen fibers during storage. [ABSTRACT FROM AUTHOR]