The method is suitable for the determination of water vapor volatile aroma compounds in beer.
Volatile aroma compounds are driven out of the sample through steam distillation. The ethanolic distillate is saturated with NaCl. Potassium hydrogen sulfite is added to separate carbonyl groups that might interfere with the analysis. The extraction of the aroma compounds is performed by shaking out with dichloromethane and the phases separated by centrifuging.
Determination of organic acids by means of reversed phase chromatography/ion chromatography
This method is suitable for wine, fruit juice and other non-alcoholic beverages.
The organic acids are separated using two combined columns, reversed-phase HPLC and an ion exchange column and are then determined using a UV detector.
The method is suitable for beer brewed to any original gravity or to any alcohol content.
Volatile compounds in beer are concentrated through distillation and extracted with dichloromethane. The solvent phase is analyzed with a gas chromatograph. The linearity of the detector and the determination of the concentrations of analytes in the sample are achieved by using multiple concentration levels within the relevant range and through evaluation of the relative area under the peaks.
Determination of the steam-volatile acids by means of titration
This method serves as a means for determining the titratable steam-volatile acids in beverages and concentrates
Volatile acids are distilled using steam, and the distillate is analyzed through titration. Sulfurous acid present in the distillate is determined iodometrically and subtracted from the total.
Determination of the vicinal diketone content (diacetyl + 2,3-pentanedione) as well as the total diketone content in beer
The method is suitable for filtered beers brewed to any original wort or to any alcohol content as well as for fermenting wort.
Diacetyl (2,3-butanedione) and 2,3-pentanedione are detected photometrically in the beer after steam distillation. It is also possible to determine precursors in green beer.
Enrichment of the PAH is performed using solid phase extraction. The extract is obtained from the sample through separation with high performance liquid chromatography on the appropriate stationary phases under isocratic conditions. Detection is conducted with a fluorescence detector. The determination is quite sensitive because these polycyclic aromatic hydrocarbons possess substantial fluorescence properties. Since the fluorescence characteristics of these substances are substance-specific, they are determined using two spectra, the excitation and emission spectra. Thus, selective detection is possible. Through recognition of the specific spectra for each substance and the means of detection at the appropriate wavelengths, maximum sensitivity and selectivity are attainable.