【作者】 刘春凤；

【导师】 李崎；

【作者基本信息】 江南大学 ， 发酵工程， 2008， 硕士

【摘要】 本文利用顶空固相微萃取/气相色谱(HS-SPME/GC)技术,建立了一种能够同时检测啤酒中醇、酯及游离脂肪酸(FFAs)的分析方法。利用Plackett-Burman试验设计法及响应面分析法,优化得到顶空固相微萃取-气相色谱检测啤酒中挥发性风味物质的最佳萃取条件:萃取温度54℃、萃取时间45 min,加盐量为0.41 g/mL。选用固相微萃取头PDMS/DVB对啤酒中的醇、酯及脂肪酸进行定性定量研究,得到乙酸乙酯、乙酸异戊酯、异丁醇、异戊醇、β-苯乙醇、辛酸和癸酸的线性范围分别为0.998~199.68、0.25~500、0.735~147、0.387~774、0.126~2515、0.4~80.8、0.46~92 mg/L,相对标准偏差(RSD)小于4 %,检测限在0.01~0.404μg/L之间,各物质峰面积与浓度之间线性相关系数均大于0.998。同时将其与顶空气相色谱法(HS-GC)及液液萃取(LLE)法进行了比较,证明了该方法的可靠性和可行性。尝试将模糊综合评价法应用于啤酒口感协调性品评中,通过与传统感观品评结果相比较,发现两者的拟和度较好。对市售的48种啤酒样品进行了口感协调性优劣排序和比较,检测分析了口感协调性排名前20的啤酒样品的风味物质含量,发现不同品牌啤酒在有机酸、醇、酯和脂肪酸几大类风味物质组成上存在较大差异。在模糊综合评价基础上,结合口感协调性品评试验,通过统计口感协调性最优啤酒样品的几大类风味物质分布,初步确定了口感协调性啤酒风味物质组成的较优范围:丙酮酸35~77 mg/L,苹果酸37~64 mg/L,乳酸53~82 mg/L,乙酸21~55 mg/L,柠檬酸113~157 mg/L,琥珀酸44~95 mg/L;异丁醇5~11 mg/L,异戊醇37~83 mg/L,β-苯乙醇21~26 mg/L,乙酸乙酯11~24 mg/L,乙酸异戊酯2~6 mg/L;辛酸1~2 mg/L,癸酸0.05~0.4 mg/L。为后面以啤酒口感协调为目标的酿造工艺的优化,即样品风味物质组成的优劣判别提供了参考依据。依据口感协调风味物质的较佳组成配比,结合样品口感模糊综合评价结果和较佳稀释率的放大验证试验得出:口感协调性较佳的样品稀释率相应较大,稀释率较小的样品的口感协调性模糊综合评价结果等级也较低,常浓酿造啤酒口感协调性品评结果较差。更多还原

【Abstract】 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.更多还原