Isolation and Identification of 4-Hydroxy-2 (or 5) -ethyl-5 (or 2) -methyl-3 (2 H) -furanone, as a Flavor Component in Shoyu (Soy Sauce)

Abstract

Unstable compounds with intense sweet odor were isolated from shoyu and identified as 4-hydroxy-2-ethyl-5-methyl-3 (2 H) -furanone and 4-hydroxy-5-ethyl-2-methyl-3 (2 H) -furanone (tautomer ratio, about 3:2) on the basis of spectrometrical investigation. This may be the rare case of isolation of the tautomeric compounds from a natural product.
They were concluded to be major and important flavor components in shoyu.