Influence of diet and season on the discoloration of dark muscle of cultured yellowtail <i>Seriola quinqueradiata</i>

Abstract

We investigated the in‰uence of diet and season on the discoloration of dark muscle of cultured yellowtail Seriola quinqueradiata. The amount of a-tocopherol (aToc) and ascorbic acid (AsA) in the diet aŠected the amount in dark muscle and discoloration was inhibited by the amount of AsA rather than the amount of aToc. Discoloration was suppressed by adding ascorbic acid derivatives to the diet. Discoloration varied depending on the season: the ratio of metmyoglobin to total myoglobin (metMb) was lower from August to October that than from December to March. The amount of AsA from December to March was low, and the pH of dark muscle from August to October was high. Although metMb was correlated with AsA content and pH, there was no correlation with aToc amount. Therefore, the amount of AsA and suppression of pH decrease were considered to be the key to suppressing discoloration.