K value of cultured southern bluefin tuna (Thunnus maccoyii) imported in chilled state, and its difference among parts of fish body

Cultured tuna is becoming one of important fish sources in Japan, which is used to be imported by airplane without freezing from abroad. It gives a better economical profit and taste, and also promises a constant supply through out a year. However, there are few data available for the freshness of tuna undergoing such kind of transportation. This study was conducted to evaluate the initial freshness indicated as Kvalue of chilled-southern bluefin tuna (Thunnus maccoyii), imported by airplane from Australia, considering the difference of K value among parts of this fish body. The total amount of ATP and its related compounds was 11.82, 9. 74, 7.83 and 5.88, u moles/ g for dorsal (red), dorsal (white), tail and abdomen muscles, respecively. Tail muscle was showing the highest K value followed by dorsal (white), abdomen and dorsal (red) muscles, respectively. As tail muscle was more active among parts of fish body before fish was being caught, so that degradation of ATP was thought to occur faster in tail. It was confirmed that the quality of the sample fish imported by airplane was fairly good, which has K value ranged between 8. 8-14. 7%. The tail muscle could be regarded as a suitable part for analyzing K value.