Abstract
Comparative determination of thiamine content in raw tuna meat, raw mackerel meat and their canned products was made by the thiochrome method with BrCN or K_3Fe(CN)_6-oxidation. Since the latter procedure gave much higher values, the causes were investigated. In the canned products, K_3Fe(CN)_6 oxidation produced fluorescent substances other thiochrome substances which were removed by L-Cysteine or by exraction with benzene・n-BtOH (75:25) as thiochrome extracting agent. The difference of thiamine contents in tuna and mackerel by two procedures was due to the presence of hydroxyethylthiamine (HET), which was in the order of 0.05-0.20mg HET-HCl eq./100g.
