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.
Determination of the content of 2,3-butanedione (diacetyl) and 2,3-pentanedione or the content of total VDK (free VDKs and precursors) after thermal conversion of the precursors
The method is suitable for beer brewed to any original gravity or to any alcohol content as well as for fermenting wort.
Diacetyl, 2,3-pentanedione and their precursors are determined by means of gas chromatography. A sample from the headspace – in equilibrium with the beer at 35 °C – is analyzed. Precursors are converted to the corresponding diketones through aeration and heating the beer to 60 °C. The evaluation of the results is performed by comparing the height of the peaks of diacetyl and against the peak for hexanedione as the internal standard.
Determination of total diacetyl in beer.
The method is suitable for beers of all original wort ranges and alcohol contents.
Beer is thermally treated to cause the precursors present in the sample to transform into their respective vicinal diketones. Using the headspace technique, the concentration of total diacetyl is determined using gas chromatography. The linearity of the detector and the determination of the concentrations of analytes in the sample are achieved by using multiple concentration levels within their relevant range and through evaluation of the relative area under the peaks. Depending upon the operating conditions of the chromatograph, the relative areas under the peaks can also be used to determine the concentrations. The method is suitable for beer brewed to any original gravity or to any alcohol content.
This method describes how to determine the gushing potential of a sample to be analyzed.
Malted and unmalted grain intended for use in beer brewing or elsewhere in the food industry
A cold water extract of a malt or adjunct (coarse grist) is concentrated through boiling; subsequently, standardized bottled water is added to the extract. The extract is filled in bottles. After the bottles have been shaken according to a defined procedure, they are opened and the weight of liquid fobbing out of the bottles as foam (gushing) is determined and taken as a measure of the gushing potential for the malt or adjunct in question.
This method describes how to classify barley according to size using a laboratory sieving machine.
Barley intended for the production of malt is to be evaluated on the basis of the characteristics described below.
A barley sample is classified into fractions according to kernel size in a sieving machine containing three sieves with defined slot widths.
This method describes how to classify barley according to size, though this is performed without separating out the half kernels.
Barley malt intended for use in beer brewing or elsewhere in the food industry.
The sieving test represents one of the most important objective physical methods for evaluating malt and can be carried out rapidly and easily. The percentages of total dockage (< 2.2 mm) and that of the kernels belonging to grades I and II can be determined from the results of the sieving test.