Effects of different drying methods on Rubus chingii Hu fruit during processing：HS-SPME-GC-MS
Description
In this study, the dried fruits of Rubus chingii Hu (Chinese name: Fu-Pen-Zi; FPZ) were processed and dried by three methods – in the shade, the sun, and the oven.The technique of headspace–solid-phase-microextraction–gas-chromatography–mass spectrometry (HS-SPME-GC-MS) and flavoromics were used to analyze the flavor-conferring metabolites of FPZ.
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The samples were ground to a fine powder and 500 mg of the powder was transferred to a 20 mL HS vial (Agilent, CA, USA), containing a saturated NaCl solution, to inhibit any enzyme present. The vials were sealed using crimp-top caps with TFE-silicone HS septa (Agilent, CA, USA). For SPME analysis, each vial was incubated at 60 °C for 5 min, then a 120 µm DVB/CWR/PDMS fiber was exposed to the HS of the sample at 60 °C for 15 min. After sampling, desorption of the VOCs from the fiber coating was carried out in the injection port of the GC apparatus at 250 °C for 5 min in the splitless mode. The identification and quantification of VOCs were carried out using a GC-MS equipped with a 30 m × 0.25 mm × 0.25 μm DB-5MS (5% phenyl-polymethylsiloxane) capillary column. Helium was used as the carrier gas at a linear velocity of 1.2 mL/min. The injector temperature was maintained at 250 °C and the detector at 280 °C. The temperature of the oven was programmed to maintain at 40 °C for 3.5 min, increase at 10 °C/min up to 100 °C, then at 7 °C/min up to 180 °C, then at 25 °C/min up to 280 °C, and hold for 5 min. The mass spectra were recorded in the electron impact (EI) ionization mode at 70 eV. The quadrupole mass detector, ion source, and transfer line temperatures were set at 150, 230, and 280 °C respectively. The MS was set at the selected ion monitoring (SIM) mode and was used for the identification and quantification of the analytes.