Research on Determination of Volatile Flavor Substances in Beer
|Keywords||Beer Volatile flavor compounds Headspace analysis Solid phase micro extraction Gas chromatography - mass spectrometry|
Substances that affect the flavor of beer, one of the most significant is the higher alcohols, esters and organic acids. The the beer higher alcohols, higher esters content ratio determines the taste and mouthfeel of the beer, the kind and content of organic acids is based on beer fermentation normal flag. Therefore, the establishment of a simple, rapid and accurate determination of beer senior alcohols, esters, organic acids analysis method is very necessary. This study established a simple and sensitive determination of volatile flavor compounds in beer static headspace - gas chromatography. Determine the optimal experimental conditions: sample equilibration time 40 min; samples equilibrium temperature of 40 ° C; the NaCl dosage to 2 g; flow rate of 1.3 mL / min; inlet temperature of 250 ° C; detector temperature 250 ° C; injection experiments splitless; temperature-programmed conditions of 40 ° C maintained for 5 min, 5 ° C / min, increased to 200 ° C and maintained for 10 min. In optimum conditions, draw the eight components of the standard curve, correlation coefficient of 0.9991-0.9999, the minimum detectable concentration of each component 0.002-09μg/mL, the relative standard deviation was 1.2% -4.6%. Eight substances in the four beer samples were measured, and the average recovery was 92.6% -98.2%. Through experiments established a simultaneous determination of beer senior alcohols, esters, organic acids and other substances headspace solid phase microextraction - gas chromatography - mass spectrometry. Experiment compared three extraction fiber: 100 uM polydimethylsiloxane (PDMS), 85μm polyacrylate (PA), the extraction efficiency of 75 microns CAR-PDMS, experimental results show that the extraction efficiency of the: 75μmCAR-PDMS extracted fibers best. Effects of extraction time, extraction temperature, the amount of inorganic salt (NaCl), analytical temperature, resolution time, the interface temperature, carrier gas flow rate, column temperature, injection measured to determine the optimal experimental conditions: extraction time 30 min ; extraction temperature 40 ° C; the NaCl dosage to 2 g; resolve temperature of 270 ° C; parse time 5 min; carrier gas flow rate of 1.3 mL / min; injection splitless; interface temperature of 280 ° C; temperature-programmed conditions maintained at 40 ° C for 5 min, 5 ° C / min increased to 200 ° C and maintained for 10 min; SCAN scan qualitative, quantitative SIM mode. Draw a standard curve of the 14 substances in optimum conditions, the linear correlation coefficient of 0.9991-0.9998, The each component minimum detectable concentration was 0.002-0.9μg/mL relative standard deviation of 1.4% -3.6%. 14 substances in the four beer samples were measured, and the average recovery was 90.5% -103.6%. The results showed that both sensitive and accurate determination of the method of analysis of the beer flavor compounds.