This study investigated the volatile flavor composition of essential oils extracted from Synurus deltoides (Arr.) Nakai. The essential oils extracted from the aerial parts of plants by the hydrodistillation extraction method were analyzed by gas chromatography (GC) and GC-mass spectrometry. Ninety-six (98.76%) volatile flavor compounds were identified in the essential oil extracted from fresh leaves of S. deltoides (Arr.) Nakai. The major compounds were 6,10,14-trimethyl-2-pentadecanone (19.91%) and phytol (12.38%). Ninety-seven (97.81%) volatile flavor compounds were identified in the essential oil extracted from shade-dried leaves of S. deltoides (Arr.) Nakai. The major compounds were phytol (51.71%), di(6-methylhept-2-yl) phthalate (7.66%), and 6,10,14-trimethyl-2- pentadecanone (4.23%). Quantitative variations of 6,10,14-trimethyl-2-pentadecanone, phytol and di(6-methylhept-2-yl) phthalate according to different state of S. deltoides (Arr.) Nakai can serve as a quality index of essential oils used in the food industry.

This study investigated the chemical composition of burdock (Arctium lappa L.) leaves essential oil, and the quantitative changes of the major terpene compounds according to the specific harvesting season. The essential oils obtained by the hydrodistillation extraction (HDE) method from the aerial parts of the burdock leaves were analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). The essential oil composition of this plant was characterized by the higher content of phytol and 6,10,14-trimethyl-2-pentadecanone. Seventy seven (98.28%) volatile flavor compounds were identified in the essential oil from the burdock leaves harvested during the spring season of 2012, and phytol (33.47%) and 6,10,14-trimethyl-2-pentadecanone (32.47%) were the most abundant compounds. Eighty eight (99.08%) compounds were identified in the essential oil from the leaves harvested during the autumn season of 2012, and in this case, phytol (37.35%) and 6,10,14-trimethyl-2-pentadecanone (34.67%) were also the most abundant compounds. These two volatile components were confirmed as the major oil components of the burdock leaves during the time of any harvest. The ratio between the two components contained in the burdock essential oils did not differ significantly by harvesting season. But overall, the essential oil harvested during the spring season contained 65.94% of the two major components, while for the essential oil harvested during the autumn season, the total amount of these two major components was 72.02%. While the main ingredients of the essential oils were found to be unchanged from one harvest time to the next, it was found to differ in content. For the burdock leaves, the quality index of the volatile constituents according to the harvest time would be more useful for utilizing the total quantity other than the proportion between phytol and 6,10,4-trimethyl-2-pentadecone.