The relation between the oxidation of phenolic compounds in shoyu and the browning of shoyu has been studied.
In this paper, ether soluble phenolic compounds in shoyu were studied. One of the phenolic compounds on TLC plate became brown without any spraying of chemical reagents (solvent system; benzene:methanol:AcOH=45:7:1 v/v). This compound was fractionated by silicic acid column chromatography (solvent; n-hexane:ether=9:1 v/v and n-hexane: ether=1:1 v/v) and separated by TLC. Resolved substance was eluted with n-hexane:ether=9:1 from adsorbent and crystallized from hot n-hexane. Rf value, mp, UV spectra and IR spectra isolated needles were the same as those of catechol.
Isolation of catechol from shoyu was first carried out in the present work.