Research On The Characteristics Of Harmonious And Soft Taste Of Beer

The method of determining alcohols,easters and free fatty acids at the same time was established by Head-space solid microextraction. The Head-space solid phase microextraction conditions for flavor compounds analysis in beer were optimized by Plackett-Burman design and response surface analysis. The optimal conditions were as follows:extract temperature, time and salt dosing was 54℃, 45 min and 0.41 g/mL, respectively. The working curve linear scope of ethyl acetate, iso-amyl acetate, isobutyl alcohol, iso-amyl alcohol,β-phenethyl alcohol, caprylic acid and capric acid was 0.998~199.68 mg/L, 0.25~500 mg/L, 0.735~147 mg/L, 0.387~774 mg/L, 0.126~2515 mg/L, 0.4~80.8 mg/L and 0.46~92 mg/L, respectively. The relative standard deviation (RSD) was less than 4 % with detection limits between 0.01~0.404μg/L and correlation coefficient more than 0.998. The reliability of this method was proved through comparing with Head-space Gas Chromatogram and Liquid-Liquid extraction.The Fuzzy Comprehensive evaluation was applied to the evaluation of harmony character of beer. We found that the fitting degree for the two methods was very well through the results of Fuzzy Comprehensive evaluation and the results of sensory evaluation. The harmony characters of 48 kinds of beer were composited, and the flavour substances of the beer ranking before 20. We found that the great discrepancy in the contents of organic acids,alcohols,easters and fatty acids of different beer samples was indeed presented. With measured of the flavour substances contents of the harmonious beer, the relative optimal range of flavour substances of the harmonious beer was considered as: pyruvic 35~77 mg/L, malic 37~64 mg/L, lactic 53~82 mg/L, acetic 21~55 mg/L, citric 113~157 mg/L and succinic acid 44~95 mg/L; isobutyl alcohol 5~11 mg/L, iso-amyl alcohol 37~83 mg/L,β-phenethyl alcohol 21~26 mg/L, ethyl acetate 11~24 mg/L, iso-amyl acetate 2~6 mg/L, caprylic acid 1~2 mg/L, capric acid 0.05~0.4 mg/L. The beer could be ranked and compared by the flavour substances content in beer.According to the relative optimal range of flavour substances of the harmonious beer and the results of the Fuzzy Comprehensive evaluation, we could obtained that the beer with higher dilution rate has the better sensory evaluation characteristic, and the beer produced by High gravity brewing owned the better harmonious characteristic than the beer produced by general brewing.