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.
This method describes the determination of four hop aroma compounds found in hops and hop products using gas chromatography.
Hops and hop products intended for use in beer brewing or elsewhere in the food industry
The hop oil obtained through steam distillation (refer to links) is dissolved in an organic solvent, separated into its components by means of gas chromatography and determined with a flame ionization detector. The contents are expressed as a percentage of the area of each component compared to the overall area of the peak.
Applicable for malt (or the wort produced from it) and all (laboratory) worts
The analysis sample (e.g., Congress wort or wort from above the grain bed during lautering) undergoes a chemical reaction with an acetic acid/thiobarbituric acid solution; the resulting product is yellow in color and is measured spectrophotometrically.
Determination of free dimethyl sulfide (DMS) and its precursors in beer
wort
Dimethyl sulfide precursors (DMSP) in the wort are converted to dimethyl sulfide (DMS) by heating under aqueous, alkaline conditions. The DMS is determined using gas chromatography by means of the headspace technique.
This method is suitable for the determination of steam-volatile aroma compounds in wort.
Volatile aroma compounds are driven out of the sample through steam distillation. The ethanol distillate is adjusted to be alkaline and saturated with NaCl. The extraction of the aroma compounds is performed by shaking out with dichloromethane and the phases separated by centrifuging. The organic phase is further concentrated in a stream of nitrogen gas. An ammonia solution is added to remove the acids, because the acids would co-elute, thus preventing quantification of the target substances.
The method is suitable for beers of all original gravities and of any alcohol content.
The gas chromatography headspace method is used to determine the higher alcohols and esters present in beer, i.e., the volatile compounds are transferred from the headspace in the sample vial into the GC system for analysis. The following substances are measured in this analysis:
Acetaldehyde
Propanol-1
Ethyl acetate
2-Methylpropanol
3-Methylbutanol
2-Methylbutanol
2-Methylpropylacetate
Butyric acid ethyl ester
3-Methylbutyl acetate
2-Methylbutyl acetate
Hexanoic acid ethyl ester