Spme vial

Solid phase microextraction-gas chromatography mass spectrometry (SPME-GCMS) was used to analyse the volatile constituents of the wines produced from the fermentation of the spiked MGJM mixtures. Aliquots of the wines (5 mL) were diluted 1 in 2 with H₂O to a final volume of 10 mL before analysis. In all cases, NaCl (3 g) was added to each SPME vial (amber 20 mL, Supelco) prior to sample addition. Samples were spiked prior to analysis with 10 µL of a solution containing the following deuterated internal standards at the specified concentrations: d₁₃-hexanol (920 mg/L); d₁₁-hexanoic acid (930 mg/L); d_16-octanal (82.1 mg/L); d₅-ethyl nonanoate (9.2 mg/L), d₃-linalool (1.73 mg/L). SPME-GCMS was carried out using an Agilent 7890A gas chromatograph (Santa Clara, CA, USA) equipped with a GerstelMP2 auto-sampler and using an Agilent Technologies 5975C mass spectrometer for detection of m/z and compound identification. SPME and chromatography conditions and compound identification were carried out as reported by Dennis et al. [8 (link)]. Quantification of the analytes was achieved by linear 5-point external calibrations (r² = 0.97–0.99). Standard compounds were added to model wine (12% aqueous ethanol, pH adjusted to 3.2 with potassium bitartrate) at five different concentrations, and further preparation of the SPME vials was analogous to the above procedure for samples.

The headspace solid-phase microextraction (HS-SPME) method was employed to extract the volatile compounds from the minced pepper samples. The volatile components were analyzed according to the methods previously described (2 (link)). Samples (30 g each) were blended with 30 ml of distilled water, and 2 g of the sample was immediately transferred into a 15 ml SPME vial (Supelco, Bellefonte, PA, USA) followed by addition of 50 μL 2-octanol (10^–6 mol/L) in methanol as an internal standard. After sample preparation, each vial was placed in a water bath at 70°C for 15 min with agitation to reach an equilibrium state. Subsequently, a fiber coated with 50/30 μm DVB/CAR/PDMS (Supelco, Bellefonte, PA, USA) was injected into the vial for 30 min to absorb volatile compounds.

A new 75 mm CAR/PDMS SPME fiber (Supelco, Bellefonte, PA, USA) was conditioned with helium at 270 °C for 2 h prior to use. After each extraction cycle, the fiber was returned to the SPME needle to prevent contamination and conditioned again with helium at 270 °C for 20 min. Extractions were performed in 15 mL Supelco SPME vials filled with 9 mL bacterial culture containing a stir bar. The vials were clamped inside a thermostatic water bath placed on a hot stirrer. The SPME needle was allowed to pierce the septum and the fiber was exposed to the headspace of the vial for 90 min at 60 °C with constant magnetic stirring. The VOCs from 9 mL KMB broth were used as controls.