Initial Volatile Aroma Profiles of Young and Aged Awamori Shochu Determined by GC/MS/Pulsed FPD

The natural vaporized aroma compounds present in awamori shochu were determined by a three-stage volatile organic compound (VOC) concentration technique consisting of on-line GC combined with MSD and PFPD. Several short-chain esters appear to predominantly contribute to the fruity aroma, including ethyl formate, methyl formate, ethyl propionate, and ethyl butyrate, which are typically contained in the natural vaporized aroma of awamori. Compounds that act as stimulant flavor compounds, including 2-methyl propanal, 3-methyl butanal, pentanal, hexanal, octanal, nonanal, and the ketones 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and 3-octanone, were also detected as minor components. Sulfur compounds that impart strong odor/flavor, such as dimethyl trisulfide, benzothiazole, dimethyl trisulfide, and benzothiazole, were detected initially, but their levels tended to decrease with aging. We also found that ethers, including tetrahydrofuran and 1,1-diethoxyethane, increased in aged awamori. Thus the profiles of these compounds changed during aging, resulting in a milder and sweeter flavor. These results suggest that the natural vaporized aroma would contribute to the initial characteristics of the unique awamori aroma.