แปลมะด๊าย ใครใจดีช่วยหนูโหน่ย Analysis of volatile compounds Volatile compounds were analyzed from the headspace of cooked burger patties by using the solid-phase micro extraction (SPME) and gas chromatography/mass spectrometry (GC/MS) following the method described by Estévez, Ventanas, Ramírez, and Cava (2004) with minor modifications as follows: The SPME fiber, coated with divinylbenzene-carboxenpoly (dimethylxilosane) (DVB/CAR/PDMS) 50/30 μm, was preconditioned prior to analysis at 220 °C during 45 min. One gram of minced sample was placed in a 4 mL SPME vial and sealed with a silicone septum. The sample was allowed to equilibrate during 30 min while immersed in water at 37 °C. During the extraction, the SPME fiber was inserted through the septum and exposed to the headspace of the vial. After extraction, the SPME fiber was immediately transferred to the injector of the chromatograph (HP5890GC series II gas chromatograph) which was in splitless mode at 220 °C. Volatiles were separated using a 5% phenyl–95% dimethyl polysiloxane column (Restek, USA) (30 m × 0.25 mm id., 1.05 μm film thickness). The GC/MS conditions were as follows: the carrier gas was helium at 18.5 psi, resulting in a flow of 1.6 mL min− 1 at 40 °C. The SPME fiber was desorbed and maintained in the injection port at 220 °C during the whole chromatography run. The temperature program was isothermal for 10 min at 40 °C and then raised at the rate of 7 °C min− 1 to 250 °C and held for 5 min. Transfer line to the mass spectrometer was maintained at 270 °C. The mass spectrometer (Agilent model 5973) operated in the electron impact mode with an electron energy of 70 eV and a multiplier voltage of 1650 V, collecting data at a rate of 1 scan s− 1 over a range of m/z 40 to 300. Volatiles compounds were whether tentatively identified by comparing their mass spectra with those from the Wiley library or positively identified by comparing its mass spectra and retention time with those displayed by the standard compounds. Results from the volatiles analysis were provided in arbitrary area units (AAU).
Posted on: Thu, 11 Jul 2013 17:38:48 +0000