Changes of proximate compositions and myoglobin content in the dorsal ordinary muscles of the cultured Pacific bluefin tuna Thunnus orientalis with growth

Abstract

Using the dorsal ordinary muscle (DOM) of cultured Pacific bluefin tuna (body length [BL]: 47.5–81.8 cm, body weight [BW]: 2.1–13.5 kg, n=15), the changes of proximate compositions and myoglobin (Mb) content with growth were investigated. There was a positive correlation (r=0.9832, P<0.05) of BL and BW in cultured tuna. The protein contents of the DOM of cultured tuna decreased (P<0.05) and the lipid contents had a tendency to increase (not significantly) with growth. The meat color changed from pink to red with growth. In addition, the Mb contents of the DOM of cultured tuna increased (P<0.05) from 1.0 mg/g (minimum BW fish) to 3.8 mg/g (maximum BW fish) with growth. These results indicate that the increase of the Mb content in the DOM of cultured tuna is not caused by the restriction of exercise and overfeeding between 2.1 kg and 13.5 kg of BW.