Identification and formation of volatile components responsible for the characteristic aroma of mat rush (igusa).

An aroma concentrate of the mat rush (igusa) was prepared by combining solvent extraction with the solvent-assisted flavor evaporation (SAFE) technique. An aroma extract dilution analysis (AEDA) applied to the volatile fraction revealed 51 odor-active peaks with FD factors between 4(3) and 4(7). Among the perceived odorants, twelve peaks with the higher FD factors (>or=4(6)) were proved to be the most important components of the characteristic aroma in mat rush. Eleven odorants were identified or tentatively identified from the twelve peaks as methional, (E,Z)-2,6-nonadienal, (E)-2-nonenal, (E,E)-2,4-nonadienal, (E,E,Z)-2,4,6-nonatrienal, trans-4,5-epoxy-(E)-2-decenal, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-hydroxy-4,5-dimethyl-2(5H)-furanone, isovaleric acid, methyl anthranirate, and vanillin. The FD factors of the odor-active peaks in dried mat rush were observed to be much higher than those in raw mat rush. This finding suggests that the drying process during manufacturing of the mat rush is one of the most important factors for the formation of the characteristic mat rush aroma.