This method describes the determination of dimethyl sulfide and its precursors in malt.
Malt intended for use in beer brewing or elsewhere in the food industry
DMS and the precursors of DMS (DMSP) are obtained from a finely ground malt sample by means of cold extraction. This aqueous extract is then boiled under alkaline conditions which converts the DMS precursors (DMSP) to free DMS. The DMS is determined using gas chromatography by means of the headspace technique.
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.
Determination of free dimethyl sulfide (DMS) and its precursors in wort and beer
wort and beer
Free DMS is determined in wort and beer with a gas chromatograph using the headspace method. Calibration is performed at various concentrations within the relevant range. The relative peaks corresponding to the concentrations are evaluated.
Determination of organic acids using ion chromatography
This method is suitable for beer, wort, green beer, NAB, water and wastewater
Separation by ion chromatography followed by conductivity detection.
Wort samples of all kinds.
Analysis of wort for beer-spoilage bacteria (anaerobic). In the case of trace infections, it may be necessary to carry out a second enrichment. Slow-growing (e.g. Pediococcus spp.) or thermally damaged microorganisms can also be detected here.
Detection of indirect beer-spoilage organisms to monitor the microbiological situation in the cold wort area.
Pitching wort
A number of different bacteria that can be found in water, also develop in hopped wort. They are summarised under the term "wort bacteria" and largely belong to the Enterobacteriaceae family. Pseudomonas spp. are occasionally found in water treatment plants. Many microorganisms can only exist or multiply in a sufficiently oxygen-rich atmosphere, i.e. under aerobic conditions.
Preliminary microscopic analysis for aerobic wort bacteria and check for wort bacteria odour after prior aerobic incubation.
To determine whether the wort contains microorganisms capable of reproduction, incubate the wort sample for up to 7 days at 27 ± 2 °C and then analyse using dark-field microscopy.