2.6. Volatile compounds analysis
Samples from unskinned semimembranosus muscle surface (1 cm
thickness) were collected from fully matured dry-cured hams (≈20
months processing time), vacuum-packaged and stored at −20 °C
until analysis. Frozen samples were minced and 1.5 g placed in a
20 ml glass vial sealed with a PTFE septum. Volatile organic compounds
(VOCs) were extracted by using a solid-phase microextraction (SPME)
device with a 75 μm CAR-PDMS coating (Supelco, Bellafonte, PA).
Prior to analysis, the fibre was preconditioned at 300 °C for 40 min at
the GC injection port. The vials were conditioned in the TriPlus
autosampler at 40 °C for 15 min. Then the fibre SPME was exposed to
the headspace for 30min. A gas chromatograph Trace GC (Thermo Electron
Corporation) equipped with mass detector DSQ II (Thermo Electron
Corporation) was used with a DB-5 capillary column (Supelco:
30 m, 0.25 mm i.d., 0.25 μm thickness). The injection was in split
mode (1:15). Helium was used as a carrier gas at 1.3 ml/min. The temperature
programmewas isothermal for 15min at 36 °C, then increased
to 120 °C at 4 °C/min, and then from120 to 250 °C at 20 °C/min. Injector
and detector temperatures were set at 250 °C.
Themass spectra were obtained by means of a mass selective detector
working in electronic impact at 70 eV, a multiplier voltage of 1650
and collecting data at a rate of 1.4104 scan/sec over the range 36–
360 uma. Compounds were identified by comparing their mass spectra
with reference spectra from the NIST 2005 version 2.0 spectral library