Beer Bacterial InfectionSeptember 30, 2011 # 4:46 AM # Microbiology # 2 Comments
Infection is due to different bacteria. Probably it is because your tank, instrument, pip line and tools are not clean enough or you do not respect sterility of the wort during brewing. A beer with an infection with bacteria is not dangerous for the health but you can have some short intestine problems. The wort has a height pH and the hops acid protects your beer against the infection, but in case of an infection you can have the following bacteria in your beer:
What are the signs of a bacterial infection?
However it happens sometimes that the beer has an infection and doesn’t smell good (off flavor) because of production of acetic acid, esters, phenol etc. or is not look good because of turbidity, surface film and flaked sedimentations.
What are the bacteria involved in beer making?
Bacteria causing problems in the brewery are following;
1. Wort bacteria
• Non-spore forming rods
• Aerobic or facultative anaerobic
• Catalase positive, Oxydase negative
• Motile as well as non motile species occur
• Simple Nutrition demand
For example of wort bacteria;
• Hafnia protea (Obessumbacterium)
• Hafnia alvei
• Klabsiella pneumoniae
• Enterobacter cloacae
• Enterobacter aerogenes
• Enterobacter agglomerans
2. Lactic acid bacteria (Beer spoilage bacterias)
• Non-sporeforming rods or Cocci
• Catalase negative
• Complex Nutrition demand
For exemple of lactic acid bacteria ;
How lactic acid bacteria spoils your beer?
• String forming (rarely)
• Diacetyl (”Sarcina sickness”)
P.damnosus > P.inopinatus
• String forming (production of ekstracellular polysaccharides)
• Fruity aroma
• Atypical taste and aroma (can vary)
3. Acetic acid bacteria
Converts ethanol to Acetic acid
How acetic acid bacteria spoils the beer?
These bacteria will converts ethanol to Acetic acid and Acetic acid to CO2