揮発性成分を利用した醸造醤油と化学醤油の簡易判別法

抄録

Japanese shoyu is divided into two main classes, genuine fermented shoyu and chemical shoyu which is prepared from chemical hydrolyzate of soybeans. About ninety samples of flavor concentrates of the two kinds of shoyu was quantitatively analyzed by use of gas chromatography (GC, liquid phase: LAC-2R-446), and it was found that two volatile components were by far larger in quantity in chemical shoyu than in genuine fermented one. The two components were identified as ethyl 4-oxovalerate and 4-pentanolide by means of combined gas chromatography mass spectrometry (GC-MS). In genuine fermented shoyu ethyl 4-oxovalerate was not detected by either GC or GC-MS method and 4-pentanolide was not contained or only a little even if contained. Consequently, chemical discrimination between genuine fermented and chemical shoyu might become easier and speedier by adopting this GC quantitative analysis of the two volatile components in comparison with the present popular analysis for detecting 4-oxovaleric acid which is proved to be contained abundantly in chemical shoyu. However, those two components are organoleptically considered not to contribute significantly to the characteristic flavor of chemical shoyu. Possible formation pathways of ethyl 4-oxovalerate and 4-pentanolide are also discussed.