The method is suitable for the determination of steam-volatile aging indicators in beer.
Volatile aging indicator substances 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. Ammonia solution is added to remove the acids, as the acids would coelute, thus preventing the quantification of important substances.
Pour-plate method and microscopy.
Determining the standard of hygiene through rinse water checks
Macroscopic counting of the colonies formed, microscopy for bacteria, yeasts, moulds
Check for microbiological vulnerabilities by detecting bacteria (moderately acid-tolerant bacteria) and yeasts in process water.
Pour-plate method and membrane filtration
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.