Determination of Characteristic Components in Essential Oils from Wisteria brachybotrys Using Gas Chromatography- Olfactometry Incremental Dilution Technique

The essential oil, obtained by steam distillation of flowers, leaves and stems from Wisteria brachybotrys Sieb.et Zucc, collected in Japan was analyzed by gas chromatography (GC) and GC-MS. The important aroma-active compounds were also detected in the oil using GC-MS/Olfactometry (GC-MS/O) and aroma extraction dilution analysis (AEDA). As a result, sixty-eight compounds from flowers of W. brachybotrys, accounting for 96.3%, were identified, and benzyl cyanide (31.7%), palmitic acid (8.7%), and (Z)γ-bisabolene (8.4%) as the main compounds. Thirty compounds from leaves, accounting for 97.3%, were identified, and phytol (46.0%), palmitic acid (8.2%), and nonanal (5.7%) as the main compounds. Twenty-eight compounds from stems, accounting for 98.7%, were identified, and geraniol (32.8%), linalool (22.1%), and nerol (10.4%) as the main compounds. A preliminary analysis by GC-MS and using Kovats’ retention indexes, lead to characterize and quantify the oil constituents, while GC-MS/O was then applied for the identification of the main odorants. By the incremental dilution method (AEDA), applied to the GC-MS/O technique, the flavor dilution (FD) factor was obtained. To our knowledge, the composition of these parts of essential oils is described here for the first time, both from the chemical and olfactometric viewpoints.