啤酒、酒类中苦味异α-酸和α，β-酒花酸检测方案(毛细管电泳仪)

HIGH PERFORMANCECAPILLARYELECTROPHORESIS SYSTEMCAPELseries SIMULTENEOUS DETERMINATION OF BITTER ISO-0-ACIDS AND a-AND 3-HOP ACIDS IN BEER INTRODUCTION It is important to quantify a-and B-hop acids (humulons and lupulons) as well as bitter iso- a-acids(isohumulons) on the all stages of beer production. Hop acids are the biochemical markers of a certain hoptype. Bitter iso- a-acids stabilize the beer foam， suppress the growth of undesirable microorganisms and givethe beer its bitter taste. MEASUREMENT METHOD The method has two stages - sample preparation and analysis. The first stage is based on the sampledegassing， extraction of acids into isooctane， evaporation and subsequent dissolving of the residual intowater / methanol mixture. Analysis is based on the differential migration of ionic forms of the analysedcompounds in the fused silica capillaries under the influence of the applied electric field. Sodium dodecylsulphate is added to the electrolyte to provide the so-called pseudostationary phase which leads to a betterresolution. Detection is done at 215 nm. To increase selectivity it is possible to switch the wavelength to 315nm during the run. MEASUREMENT RANGE Determination of the total hop and bitter acids concentration is done by normalization for the each acid group.In general， the measurement range for bitter acids is 5-200 mg/L， for hop acids 1-100 mg/L. EQUIPMENT AND REAGENTS The"CAPEL-105/105M" capillary electrophoresis system is used in measurements. Data acquisition， collection， processing and output are performed using a personal computer running under“WINDOWS@ 2000/XP”operating system with installed dedicated software package for acquisition andprocessing of chromatography data. All reagents must be of analytical grade or higher. EXAMPLES OF REAL ANALYSES Buffer： borate， with SDS， pH 9.18 Capillary： Leff/ Ltot 65/75 cm， ID 50 pm Sample： light beer， initial volume 10 mLMeasurement results： 1-3-iso-a-acids (total concentration 36.7 mg/L) 4 and 5-a-and B-acids (totalconcentration 4.3 mg/L) Other beer components， which can be determined by capillary electrophoresis method are following： Cations and anions in water for brewing processes； Organic acids； ● Vitamins (B complex， ascorbic acid)； Amino acids： Amines (histamine， volatile alkyl amines)； Preservatives and coloring agents in finished products. Lumex°_WWW.LUMEX.BIZ he content of this application note is subject to change without notice.WWW.LUMEX.BIZ 在啤酒生产的各个阶段，对α-和β-酒石酸（苦味酸和蛇麻素）以及苦味异α-酸（同分异构体）进行定量研究是很重要的。酒花酸是某些啤酒花型的生化标志物。苦异α-酸稳定啤酒泡沫，抑制有害微生物的生长，给啤酒带来苦味。毛细管电泳法的测定分为两个阶段：样品制备和分析。第一阶段是基于样品脱气、酸萃取成异辛烷、蒸发后将残渣溶解到水/甲醇混合物中。第二阶段是基于在所施加电场的作用下，所分析化合物的离子形式在熔融石英毛细管中进行差分迁移。在电解液中可加入十二烷基硫酸钠以提供所谓的拟稳态，从而得到更好的分辨率。检测波长为215 nm，为了提高选择性，可以在运行期间将波长切换到315nm。