Identification of 2,4-Dihydroxy-2,5-dimethyl-3(2H)-thiophenone as a Low-Molecular-Weight Yellow Pigment in Soy Sauce

Abstract

The color of soy sauce is considered to be mainly attributable to melanoidins formed by the Maillard reaction. However, the chemical structure of melanoidins cannot be clarified, because melanoidins are high-molecular-weight heterogeneous polymers. We isolated a low-molecular-weight pigment from soy sauce and identified 2,4-dihydroxy-2,5-dimethyl-3(2H)-thiophenone as this pigment formed by the Maillard reaction, although its contribution to the total color of soy sauce was very low.