Horák Tomás, Culík Jirí, Jurková Marie, Cejka Pavel, Kellner Vladimír
Research Institute of Brewing and Malting, Brewing Institute-Prague, Lípová 15, Prague 2, Czech Republic.
J Chromatogr A. 2008 Jul 4;1196-1197:96-9. doi: 10.1016/j.chroma.2008.05.014. Epub 2008 May 13.
Free medium-chain fatty acids in beer originate from raw materials, mainly from the fermentation activity of yeasts, and can influence beer taste, vitality of yeasts and also the foam stability of beer. This study presents the development of the method for the determination of free fatty medium-chain acids including caproic acid, caprylic acid, capric acid and lauric acid in beer or wort using stir bar sorptive extraction (SBSE). The combination of this extraction technique with solvent back extraction of the extracted analytes and subsequent gas chromatographic analysis with flame ionization detection was used for the determination of these compounds. The influences of different solvent back solutions, sampling time, solvent back extraction times and different contents of ethanol were studied. The method had high repeatability (RSD <6.7%), good linearity (the correlation coefficients were higher than 0.9963 for quadratic curves over the concentration range 0.5-8.0mg/l) and recoveries 57-89%.
啤酒中的游离中链脂肪酸源于原材料，主要来自酵母的发酵活动，并且会影响啤酒的口感、酵母活力以及啤酒的泡沫稳定性。本研究介绍了使用搅拌棒吸附萃取（SBSE）测定啤酒或麦芽汁中游离脂肪酸中链酸（包括己酸、辛酸、癸酸和月桂酸）的方法的开发过程。该萃取技术与萃取物的溶剂反萃取相结合，随后采用火焰离子化检测气相色谱分析来测定这些化合物。研究了不同溶剂反萃取溶液、采样时间、溶剂反萃取次数以及不同乙醇含量的影响。该方法具有高重复性（相对标准偏差<6.7%）、良好的线性（在0.5 - 8.0mg/l浓度范围内二次曲线的相关系数高于0.9963）以及57 - 89%的回收率。
