Lipid oxidations in ordinary and dark muscles of fish: influences on rancid off-odor development and color darkening of yellowtail flesh during ice storage

We investigated the role of lipid oxidation in the development of a rancid off-odor in the early stage of ice storage in both ordinary and dark muscles of cultured yellowtail (Seriola quinqueradiata). The total lipid hydroperoxide content and thiobarbituric acid-reactive substances (TBARS) of the dark muscle were significantly higher (P < 0.01) than those of the ordinary muscle during 2 d of ice storage. The increase in the metmyoglobin content of the dark muscle was accompanied by gradual darkening of the muscle color during ice storage. To distinguish the changes in odor characteristics of the muscles, sensory evaluation was carried out. Slight changes in the intensity of 7 different odors were noted in the ordinary muscles, and there was a significant increase in the overall, fishy, spoiled, and rancid smells of the dark muscle during 2 d of ice storage. No correlation was found between the total content of lipid hydroperoxide and the odor intensities in ordinary muscle; however, there was a significant correlation between the total lipid hydroperoxide content and rancid off-odor and overall smell intensities in the dark muscle. The rate of lipid oxidation of the yellowtail dark muscle was significantly faster than that of the ordinary muscle. Lipid oxidation of the dark muscle was closely related to meat darkening and development of the rancid off-odor during the early stage of ice storage.