食品中のビタミンCの定量法に關する知見

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Introduction : The substances resembling reductones are found in the dried seeds, certain vegetables, animal tissues as well as cooked and preserved food. It has been known that these substances interfere the dichlorophenol-indophenol titration method for vitamin C.The method for estimation of true vitamin C in the presence of these reductones and allied substances are to be discussed.Chapter I. On the relations between the pH value of titration and the influence of reducing substances.The reducing substances which may be present in the meta-phosphoric acid exts. of plant and animal tissues can be divided into 3 classes according to their behaviours with indophenol reaction.substances of class I, (glutathion, cystein, tannic acid and pyrogallol) react with dichlorophenol-indophenol at pH 4.0 or on. To eliminate the error which is caused by the interference of these substances, the titration should be carried on the acidic side, i. e. at pH 1.8-4.0. Substances of class 2,(of which only number so far encounbered is ascorbic acid) react with dichlorophenol-indophenol equally throughout pH 1.8-4.7. Substances of class 3,(reductones, ferrous salts and thiosulphates) readily react with dichlorophenol-indophenol at pH 1.8-4.0 but only veay slowly at pH 40 or on.
社団法人日本生物工学会の論文
1950-03-15