Constituents of Top Note Aroma of Shoyu

Abstract

As a continuation of our effort to identify the flavor constituents of Shoyu by means of the GC and GC-MS techniques, we have carried out the isolation and identification of compounds in the top note aroma of freshly heated Shoyu. Some of the identified compounds responsible for this aroma were subjected to the quantitative analysis. Shoyu flavor volatiles were isolated by using the methods; ( 1 ) vaccum co-distillation with water followed by freeze concentration and fractionation by preparative gas chromatography, ; ( 2 ) condensation of headspace volatiles given off during sweeping with pure helium gas followed by solvent extraction. The fractionated condensed volatiles were analyzed by GC-MS fitted with packed and glass capillary columns.
Fifty-four compounds were identified (Table 5). Among them, 6 compounds i. e. allyl alcohol, furan, 2-methylfuran, methyl acetate, ethyl 2-methylbutanoate and 1, 1-diethozy-2methylbutane were detected for the first time as Shoyu flavor constituents. Additionally, the major 14 compounds of these constituents were quantitatively determined by direct gas chromatographic analysis of headspace vapors (Table 2) and discussed with respect to the top note aroma of Shoyu.