Abstract
In the previous paper, the authors reported on the precipitate which was considered as one of the causes of thiamine loss, when high concentration of tannin and thiamine were mixed. The mechanism of thiamine loss in the case of low concentration of tannin solution, which was so tiny that no precipitate was formed even when mixed with thiamine, was further examined.
A marked decrease of thiamine was observed when the thiamine and tannin mixture was brought to pH 7 at 60.The products formed in this reaction was analysed with paper chromatography and others. A small amount of thiamine disulfide (TDS) was found. The longer the reaction time continued, the more the thiamine decreased.But the amount of TDS formed was not always incresed in proportion to the thiamine loss.Besides TDS, thiochrome, vitachrome, thiothiamine and thiazole compound were detected by various methods.Thiamine-decomposite formed by tannin was not recovered by the addition of acid. From an evidence of little change of TDS by tannin, it was proved that TDS would hardly be decomposed by tannin.Finally, at this reaction, TDS seemed to be formed only a little and the majority of thiamine is probably destroyed to physiologically inactive compounds.
