Determination of the fermentation cellar yield in order to monitor brewhouse operations
Wort from the midpoint of chilling/pitching wort
The fermentation cellar yield is calculated using the value determined for the amount of extract contained in a batch of wort relative to the amount of extract present in the raw materials used to produce the wort.
Determination of the overall brewhouse yield during wort production in order to monitor brewhouse operations
Wort from the midpoint of chilling/pitching wort
Since determination of the hot wort yield can be problematic and the cold wort yield as described above does not represent a measure of the total extract obtained from the grain bill, an attempt has been made to record all of the extract recovered, with the exception of that remaining in the spent grain. This value is then compared to the laboratory yield. The result is expressed as the total yield (overall brewhouse yield) (OBYCW) in %.
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
Applicable for all (laboratory) worts
The Congress wort is heated in order to inactivate the amylolytic enzymes, and afterwards, yeast is added and the wort is allowed to completely ferment out at a minimum temperature of 20 °C in a fermentation tube (fig. 1). The difference in the extract before and after fermentation is measured in order to calculate the limit of attenuation.
The method is suitable for beers of all original wort ranges and alcohol contents.
Volatile compounds in beer are concentrated through distillation and the distillate is quantitatively determined by direct injection into 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.
This method is suitable for beers exhibiting all ranges of original gravity and alcohol concentrations.
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.