Intro to CONTAMINATION

A beer spoiler overview. Although only a few types of organisms can adapt to the acidic environment of beer and beer lines, they can alter the appearance, aroma and flavor of beer. These bacteria are known as beer spoilers. While beer spoilers are not hazardous to human health, their side effects are usually manifested the day after ingestion.

The most common side effects are loose bowels and the "draft beer drools" or the runs. Beer spoilers that reach high concentration levels can cause tumbling during pour to occur and cloudiness within the beer itself. Furthermore while such organisms can produce chemical byproduct which can result in strong off taste and odors. There are up to 27 types of bacteria that can grow in the beer brewing process. For this overview, we focus on the most common contaminants. 

Visible Beer Spoilers

​These types of spoilers are the most easily recognized types of beer spoilers due to them being visible without a microscope.

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Beer Stone

Deposits of calcium oxalate, insoluble proteins and other materials are referred to as "Beer Stone".  Beer contains calcium, which is introduced into the brewing process from raw materials such as grains. Oxalic acid or oxalic salts are present in hops and formed during the germination of barely and in the course of malting. Calcium ion and oxalic can form compounds called calcium oxalate. Beer stone appears gray or brown within a faucet or the inner wall of a beer line. If not properly cleaned, the beerstone can build up in a draft system, causing problems with pour, including foam and tumbling.

Mold

The most likely source of a draft system being introduced to mold contamination is by exposure to the atmosphere. Even small amounts of beer surrounding a faucet or coupler assembly can easily support the growth of molds. Molds will generally appear as brownish solid material, which can be present on the outside of couplers, vinyl jumpers and faucets.

Yeast

​Many types of wild yeast present in the air can grow on faucets or in a keg. They can cause surface growth when the lines are not cleaned regularly and properly or if beer warms above 50 degrees Fahrenheit. Beer provides an excellent food source to promote the growth of yeast. Yeast appears as either a heavy surface film or as a white colored substance.

Bacterial Contamination

The unseen but well known contamination that causes bitter beer tastes, foul smells and distorted appearances.

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Accetobacter 
​Accetobacter bacteria produces large amounts of acetic acid. This causes beers to become sour, ropey, turbid and discolored.

​Lactobacillus
​This bacteria can make beer appear cloudy. Large amounts of lactic and acetic acid are produced which causes beers to become sour in taste. Some strains of Lactobacillis also produce diacetyl which causes a buttery taste.

​Pectinatus
When Pectinantus bacteria effects beer, it becomes cloudy. smells like rotten eggs and is sour tasting. Acetic and lactic acid, methyl mercaptan, dimethyl sulfide and hydrogen sulfide are all produced by this bacteria.

​Pediococcus
A bacteria similar to Lactobacillus, Pediococcus. It often gives beer a popcorn butter aroma.