Abstract
In our previous paper, it was reported that the L-ascorbic acid-L-histidine system gave the characteristic color product in the aqueous solution.
In order to make a further research of the browning mechanism, the effects of pH, several kinds of metalic salt, thiourea and sucrose on this system were investigated; and also, the chromatographic studies on the colored solutions were carried out.
The results of these experiments were as follows:
1. The most remarkable color development in this system was observed at the stage of pH 6-8; and also, the color development in the dehydroascorbic acid-L-histidine system was similarly remarkable at the same stage of pH.
2. The browning of this system was accelerated by Fe and Cu (chlorides), considerably, inhibited by Sn, Zn, Mg (chlorides), thiourea and sucrose, and almost perfectly inhibited by N2 or H2.
3. The hydrolysates of these colored solutions gave two ninhydrine-positive spots in addition to that of L-histidine in the paper chromatography.
This fact seems to suggest that L-histidine is immediately responsible for the browning mechanism of these systems.
