Characterization of Niacin of Skipjack Tuna Muscle and Change of the Niacin Content during Storage

Abstract

Niacin content in the upper and lower ordinary muscles (0.91±0.06-0.93±0.05 mmol/total tissues) of skipjack tuna showed a much higher level than in the liver or dark muscle. Most (98.4±0.8%) of the niacin was free form, and not bound to protein in the tuna muscle. The amount of the coenzyme forms of niacin, NAD (H) and NADP (H), was scarcely contained in the tuna muscle. The muscle niacin of skipjack tuna was not lost during storage at 4°C for 5 days. These results indicate that the tuna ordinary muscle is an important dietary source of niacin.