Basic Brewing Microbiology

Unlike traditional breweries, most craft breweries are not designed by brewery engineers or brewing microbiologists. As such, brewhouse and fermentation are very often housed in the same room! In contrast, traditional breweries were designed to separate the hot/cold side of brewing. The fact that malt dust contains many beer spoilers is just one of a plethora of reasons why.

The brewery is a very dirty place with many sources of potential beer spoilers. Examples include water, air, malt dust, traffic into the brewery, sewers, fruit flies (or other critters).

Fortunately, there are practical aseptic techniques that can help to overcome common beer spoilers. For starters, set aside a room isolated from the brewhouse to perform contamination testing. Testing wort/beer for contamination requires a clean space in which to work. Furthermore, clean clothes/lab coat reduces the chance of false positive results.

Always follow aseptic work habits. Hand and work surface cleanliness are a must. Sanitize your hands with 70% isopropyl alcohol. Lysol can be used on work surfaces.

Vessels, bottles, and equipment must be treated aseptically. Vessels/bottles used to collect samples must be sterilized by heat. All transfer pipettes must be purchased sterilized otherwise they must be sterilized by heat. Sample valves must be free of dried wort/beer from the previous sampling, sprayed with 70% isopropyl alcohol and flamed.

Due to practicality, brewers must sanitize tanks, hoses, etc. However, laboratory supplies can be either sterilized in an autoclave or pressure cooker (if not in their purchased sterile state).

Download this informative PPT by David Bryant of BSI. In it you will find key tips on how toDownload brewing tutorial perform a quick and dirty “film test” for bottled beer, using a microscope to evaluate samples, and detection of spoilage organisms using selective media.

For more information on basic brewing microbiology and more, visit our Legacy Resources page and see our Brewing Without the Blindfold booklet.

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