Study On Extract And Analysis Method Of Four Aging Flavor Compounds In Beer

Beer, which is one of essential substances in human living, is a kind of fermented drink with rich nutrient. In the modern society, people become stricter on the quality of food. The flavor of beer is an important parameter of the quality of beer. During the process of the production, storage and transportation of beer, it will gradually generate unpleasant smell which is named Aging flavor. Different types of beer with different routes and rates generate different aging flavor. Establishing an analysis method for testing aging flavor in beer, which is not only can evaluate the extent of the aging of beer effectively, but also can monitor the quality of beer, is very important.A high performance liquid chromatographic method was established for the simultaneous determination of four main aging flavor compounds in beer. The influence of the component and proportion of the mobile phase, the flow rate, the detection wavelength, the column temperature and the injection volumn on the separation and determinantion of four components were studied. The optimal conditions included a Platisil C18column. A system composed of methanol and water acted as the mobile phase using a gradient elution style, and the flow rate was1.0mL·min-1. The maximum absorption wavelength for each component acted as detected wavelength which was changing with time. The column temperature was30℃and the injection volumn was10μL. Under the optimal condition, the linear correlation coefficients of working curves ranged from0.9996to0.9999. The linear range was greater than or equal to10. The detection limits were0.002～0.003μg·mL-1(S/N=3). The average recoveries of samples were87.1%～108%and the relative standard deviations were2.6%～5.5%. The simultaneous determination of5-(hydroxylmethyl)-2-furaldehyde,2-furaldehyde, phenylacetaldehyde and E-2-nonenal in beer could be performed in30minutes.Additionally, a capillary column GC method was established for the simultaneous determination of four main aging flavor compounds in beer. The influence of the column temperature, the flow rate of carrier gas and hydrogen, the injection temperature, the detector temperature, the injection volumn, the injection mode and other factors on the separation and determinantion of four components were studied. The optimal conditions included a HP-5MS capillary column with temperature programming was used. Nitrogen acted as the carrier gas, and the flow rate was5.4mL·min-1. The flow rate of hydrogen and air were37.7mL·min-1and380mL·min-1, respectively. The injection temperature was280℃, and the detector temperature was320℃. We use the splitless injection mode, and the injection volume was1μL. Under the optimal conditions, the linear correlation coefficients of working curves ranged from0.9994to0.9999. The detection limits were0.01～0.06μg-mL-1(S/N=3). The average recoveries of samples were81.7%～107%and the relative standard deviations were3.2%～8.5%. The simultaneous determination of5-(hydroxymethyl)-2-furaldehyde,2-furaldehyde, phenylace-taldehyde and E-2-nonenal in beer could be performed in11minutes.In order to extract four targeted compounds in beer samples effectively and attained the purpose of refining samples. The extract methods of four aging flavor compounds in beer were studied systematically. Through the experiment, liquid-liquid extraction to extract four aging flavor compounds in samples simultaneously was used and the optimal pretreatment conditions were determined as follows:Acetonitrile and ethyl acetate acted as the solvent extraction, and the volumn fraction of acetonitrile and ethyl acetate was20%. The volatilization temperature was40℃, and volatiled nearly to dryness (40℃, volatiled3h). The quantity of NaCl was10%(2.0g NaCl was added into20mL sample), and extract time was5min. The quantity of sample and extratant were20mL and10mL, and the number of times of extraction was once. The extract efficiency of four aging flavor compounds was above60%and they were enriched6.0to17.2times.The results of this study showed that the HPLC method was sensitive, and had a good analytical performance. The capillary column GC method was easy, rapid and low cost. These two analytical methods were both suitable for the simultaneous determination of5-(hydroxymethyl)-2-furaldehyde,2-furaldehyde, phenylacetaldehyde and E-2-nonenal four main aging flavor compounds in beer.