Analysis of the aroma component was performed on a Thermo Finnigan Trace GC (Thermo Elecron, San Jose, Calif., U.S.A.) coupled to a Trece DSQ mass spectrometer. The gas chromatograph was equipped with an HP-INNOWax capillary column --- and the carrier gas used was helium ---- constant flow. The GC oven temperature was programmed from 40c (maintained for 2.5 min) to 200c at a rate of 5c/min, and then 200c to 240c at a rate of 10c/min. The final temperature was mintained for 1.5 min. The GC to Ms transfer line was held at 280c The mass spectrometer was operated in the electron impact ionization (EI, 70 eV). The range of mass --- was scanned from 35 to 400.
The compounds were identified by matching their mass spectra with the data stored in the National Institute of Standards and Technology (NIST) library and were confirmed by comparison of the retention time and massspectra obtained from samples with those from pure commercially available standards injected under the same conditions