Research On Determination Of Volatile Flavor Substances In Beer

There are a lot of materials that influence beer flavors, the most important substances are alcohols, ethers and acids. The content and proportion of alcohols and ethers decides the taste and texture of beer, and the kinds and content of acids is an important indicator to judge whether beer fermentation is normal. So, it is important to establish a simple, quick and accurate method on analysis of alcohols, ethers and acids in beer.This research established a simple and sensitive HS-GC method on analysis of the main volatile flavors in beer. Through experiments, the best experiment parameters were established:sample balance time was 40 minutes; sample balance temperature was 40℃; the amount of NaCl was 2 g; the flow rate was 1.3 mL/min; inlet temperature was 250℃; detector temperature was 250℃; the injection was made in the splitless mode; the oven temperature program was 5 min at 40℃and then 3℃/min to 200℃for 10 min. In the optimized detection condition, the calibration curves were protracted and the correlation coefficient ranged from 0.9991 to 0.9999. The minimum detection concentration were between 0.002 and 0.9μg/mL, the relative standard deviations (RSD) for all analytes were in the range of 1.2-4.6%, the average recovery of samples was in the range of 92.6%-98.2%.A simple and sensitive method for the analysis of beer volatile compounds was optimised using headspace solid-phase microextraction (SPME) and gas chromatography with mass detection. The fibers tested for the extraction of the volatile compounds were as follows: 100μm PDMS,85μm PA, and 75μm CAR/PDMS. Headspace SPME using a 75μm Carboxen-polydimethylsiloxane (CAR-PDMS) fiber provided effective sample enrichment and enabled extraction of a wide variety of compounds. The extraction temperature, extraction time, amount of NaCl, desorption temperature and time, interface temperature, the flow rate, oven temperature, the injection mode were modified through experiments. Through experiments, the best experiment parameters were established:extraction time was 30 minutes; extraction temperature was 40℃; tht amount of NaCl was 2 g; desorption temperature was 270℃; desorption time was 5 minutes; the flow rate was 1.3 mL/min; the injection was made in the splitless mode; interface temperature was 280℃; the oven temperature program was 5 min at 40℃and then 3℃/min to 200℃for 10 min; the qualitative analysis was in scan mode, and quantitative analysis was in sim mode. In the optimized detection condition, The calibration curves were protracted and the correlation coefficient ranged from 0.9991 to 0.9998. The minimum detection concentrations were between 0.002 and 0.9μg/mL. The relative standard deviations (RSD) for all analytes were in the range of 1.7%-3.6%. The average recovery of samples was in the range of 90.5%-99.7%.The experimental results of the research suggested that two analytical methods for the determination of main volatile fraction in beer were sensitive and accurate.