Gas Chromatography)Mass Spectrometry (GC-MS).Volatile compounds were analyzed using an HP 5890 Series II GC/HP 5972 mass selective detector system (Hewlett-Packard Co., Palo Alto, CA). One microliter of extract was injected into DB-Wax (or DB-5ms) (60 m length 0.25 mm
i.d. 0.25 ím film thickness; J&W Scientific, Folsom, CA).Helium was used as carrier gas at a linear velocity of 25 cm/s.Oven temperature was programmed from 40 to 200 °C at a
rate of 3 °C/min with initial hold times of 5 and 60 min. GCMS conditions were as follows: splitless mode; injector temperature, 200 °C; 60 s valve delay; capillary direct interface
temperature, 280 °C; ionization energy, 70 eV; mass range,33-350 amu; electron multiplier voltage, 1824 V (200 V above autotune); scan rate, 2.2 scans/s.