Search: Beer-spoiling bacteria

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.

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.

Determination by means of reversed phase chromatography after pre-column derivatization with dansyl chloride and fluorescence and UV detection.

Biological process control in breweries involves testing water, wort, yeast, beer, air, and gases that are in contact with wort and beer as well as other substances, e.g. clarifying agents, for microbial contamination. In addition, the pipework of beer, water and pressurised gas as well as equipment, machines and containers that come into contact with water, wort, yeast or beer are tested.

In all these tests, the aim is to detect obligate beer-spoilage organisms in particular, but in special cases also those that can lead to beverage contamination as potential beer-spoilage organisms.

"Indirect beer-spoilage organisms" are microorganisms that can damage intermediate products such as yeast and wort, whereby this preliminary damage can be carried over into the bottled beer (e.g. Enterobacteriaceae in the wort pathway or in propagation systems)

"Indicator organisms" are microorganisms that do not pose a risk to the biological shelf life of the finished product, but do indicate that cleaning and disinfection measures have been carried out inadequately or that mistakes have been made during production (e.g. yeast culture in rinsing water and acetic acid bacteria in the bottling area).

Table 1 shows which microorganisms can be expected in which stages of production in the brewery.

In addition, reference is made to current and relevant literature that allows the further characterisation and evaluation of potential beer-spoilage bacteria, obligate beer-spoilage bacteria, indicator bacteria, foreign yeasts, yeast cultures and other microorganisms that are relevant to breweries.

Detection of anaerobic mesophilic and thermophilic bacteria using the pour-plate method.

Membrane filtration and anaerobic incubation