Abstract:

A method has been established for the analysis of flavor compounds in wheat by headspace sorptive extraction (HSSE). The sorptive extraction bar was composed of a silicon rubber coating and a capillary glass with an inner iron rod. The silicon rubber coating was condensed inside a stainless steel mold from the silicon precursors with a sol-hot air vulcanization method. The coating of the extraction bar has a volume of about 87 μL and is thermally stable until 390 ℃. The flavor compounds extracted by the bar were desorbed in a homemade thermal desorption unit (TDU) and introduced directly into a pre-column in a gas chromatograph for analysis. Experimental parameters for the extraction efficiency were optimized including extraction temperature and time, phase ratio and thermal desorption conditions. The standard wheat flour samples spiked with seven flavor compounds were analyzed under the optimized conditions, and showed good linear relationships (r>0.9979), limits of detection (LOD) of 0.09-1.00 μg/kg, good recoveries (95%-121%) and repeatabilities (relative standard deviations, RSD, 2.2%-7.8%). By external calibration method, the absolute contents of the seven flavor compounds in a real wheat sample were determined. The method is rapid, simple with low limits of detection, and is applicable for the rapid quantitative analysis of the flavor compounds in wheat.

Key words: flavor compounds, gas chromatography (GC), headspace sorptive extraction, silicon rubber extraction bar, sol-hot air vulcanization method, wheat