Effects of bleeding on the volatile flavor compounds in skipjack tuna

The volatile flavor compounds in ordinary muscles with and without bleeding of skipjack tuna Euthynnus pelamis were analyzed by gas chromatograph-mass spectrometry (GC/MS) and compared. The contents of aldehydes and alcohols in ordinary muscle of skipjack tuna with bleeding were significantly lower (p < 0.05) than those without bleeding. The aldehydes and alcohols were generated when the blood and lipid separated from the skipjack tuna were incubated in phosphate buffer (pH 6.0) for 2 days at 5 degrees C. However, they were not generated in one side of blood and lipid. The aldehyde and alcohol levels both increased with blood concentration in the range from 0 to 100 mu L by the reaction of 100 mg of lipid. These results suggest that the aldehydes and alcohols from the skipjack tuna might be generated by the reaction of blood and lipid. Moreover, the bleeding of skipjack tuna could be effective for reducing fish odor.