Studies on flavor components in Shoyu. I. Identification of volatile components in Shoyu(soy sauce) by gas chromatography-mass spectrometry.

A shoyu flavor concentrate was prepared with as much precaution as possible not to damage the original. The procedure consisted of distillation under reduced pressure, extraction with dichloromethane, and then concentration. The odor of this concentrate seemed to be almost the same as that of original shoyu. Another concentrate containing minor components was fractionated from the above concentrate by a gas chromatographic method. These two concentrates were analyzed by use of combined gas chromatography-mass spectrometry. Fifty components were identified, fifteen of which have not been reported previously in shoyu. They are 2-hexanone, 2-methyl-3-tetrahydrofuranone, 4-pentanolide, furfuryl acetate, ethyl phenylacetate, 2-phenylethyl acetate, 2-methylpyrazine, 2, 6-dimethylpyrazine, 2, 3-dimethylpyrazine, 2-ethyl-6-methylpyrazine, 3-ethyl-2, 5-dimethylpyrazine, borneol, bornyl acetate, benzyl alcohol and 2, 6-dimethoxyphenol.