Beer

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Changed on: 09.06.2016

Beer is an alcoholic and carbonated beverage that has been made of cereals, hops and water that have been mixed and boiled and fermented using yeast. Alcohol-free beer has a maximum alcohol content of 0.5 % abv using special manufacturing processes. 
Beer is differentiated in bottom and top-fermented beer, depending on the yeast used during the main fermentation process. Only pure yeast strains are used in fermentation. Mixed yeast cultures may be used only for specific top-fermented beers.

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Beer is an alcoholic and carbonated beverage that has been made of cereals, hops and water that have been mixed and boiled and fermented using yeast. Alcohol-free beer has a maximum alcohol content of 0.5 % abv using special manufacturing processes. 
Beer is differentiated in bottom and top-fermented beer, depending on the yeast used during the main fermentation process. Only pure yeast strains are used in fermentation. Mixed yeast cultures may be used only for specific top-fermented beers.

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Microorganisms

Beer is an alcoholic and carbonated beverage. It is made of cereal grains, hops and water and is fermented using yeast. Various microorganisms are desired to be present in beer, such as yeast or lactic-acid bacteria. However, there are also microorganisms that can make beer unfit for human consumption.

Bacteria damaging to beer cause damage to the beer’s aroma and flavour (abnormal flavours), cloudiness and/or trub (sediments). They are not harmful to health, but are not expected or wanted by consumers.

Microorganisms that pose a health risk, such as faecal bacteria (coliform bacteria) must not be present in beer. Pathogens are rare in beer because they cannot reproduce. This is a result of the acidic pH value, alcohol and CO2 content.

Microorganisms  Occurrence

Yeast

natural

Lactic acid bacteria

Not required for brewing (except special beer), not harmful, consciously eaten in yoghurt and sauerkraut

Escherichia coli/Coliform bacteria

Faecal bacteria, must not be present

Pathogens

No growth in beer as a result of pH value, bitter substances, alcohol, CO2

Abnormal Flavours, Cloudiness

Beer aroma is caused primarily by the raw ingredients used, namely malt and hops, as well as the yeast metabolism. Abnormal beer aromas may have different causes. Off-flavours can occur because of technological errors, such as errors during fermentation, lacking evaporation or oxygen injection. However, they can also be caused at microbiological levels, by bacteria, moulds or yeasts. Such abnormal flavours are:

  • Celery taste: caused by the development of thermal bacteria during a delayed fermentation onset because of bad ventilation or adding too little yeast
  • Flowery, often gall-bitter taste: caused by exogenous yeast 
  • Sour taste: caused by a massive infection with lactic acid bacteria 
  • Butter taste (diacytyl): caused by an infection with pediococcus 
  • Vinegar taste (acescence): caused by acetic acid bacteria 
  • Mouldy taste: caused by the metabolic activity of certain species of mould and bacteria in wet filter aids or bottle caps, for example

Bacteria damaging to beer (obligatory beer spoiling organisms) are an inhomogenous group of often gram-positive and catalysis-negative coccus and rods (such as lacto bacillus, pediococcus) and become predominant after the fermentation or maturing process. They spoil any beer they contaminate. The can be grown over several beer batches and cause abnormal odours and flavours, cloudiness and/or trub.

Exogenous yeast is a term for all yeast strains not identical with the cultivated yeast used in brewing beer. Exogenous yeast of the non-saccharomyes family is yeast that may cause undesired organoleptic properties (e.g. abnormal flavours or taste) in beer.

Labelling

Beer is labelled in accordance with the regulations of Article 5 para. 2 of the Austrian Food and Consumer Protection Act, as amended, "Ban on Misleading Claims", Article 4 para. 1 Food Labelling Regulation 1993, as amended, "Obligatory Labelling Elements" and the Austrian Food Code III. Edition Code Chapter B 13 "Identifications".

Unfiltered beer sold on the market (e.g. "Zwickel", "Keller") has a cloudiness that stems only from the yeast used and from insoluble proteins. Draught beer without any special identification is considered "Vollbier".

Finished beer creates a set of conditions that only allows the growth of certain microbial groups. The lack of oxygen in beer (usually below 0.5 mg O2/l) prevents the growth of aerobic germs. Any other remaining anaerobic, microaerophile or even facultative pathogens would have to withstand acid (pH 4-5) and be hop tolerant (20-40 IBU).

Beer contains the following nutrients: dextrins, protein fractions, vitamins (B group), minerals and trace elements. The CO2 present (0.40-0.55 %) inhibits most germ growth.

Examinations

In Austria, beer samples are taken as part of official food inspections (carried out by the local food safety authorities) on a routine basis, as part of a targeted campaign or when reasonable suspicion arises. The samples are analysed by AGES or the food examination centres in Vienna, Carinthia and Vorarlberg. A total of 233 beer samples were analysed in 2012. None of them were assessed as a health risk. However, about 18 percent of the samples were rejected mainly because of labelling issues or misleading information. Only two samples were rejected based on microbiological contaminations. Tests conducted in previous years showed a similar picture:  

Year Tested Complaints Harmful to health ot fit for consumption Microbiologically contaminated
2012 233 18 % 0 2 2
2011 196 14 % 0 1 3
2010 248 24 % 0 3 3

table: official tests on beer; excerpt taken from the Food Reports 2010-2013 

Hygiene in Micro and Pub Breweries has Improved

Austrian pub and micro breweries have experienced a boom in recent years. However, hygiene was an issue a few years ago. Fortunately, countermeasures have brought considerable improvements.

Tests focusing primarily on samples from micro and pub breweries between 2007 and 2009 resulted in a significant rejection rate, mainly related to hygiene issues related to the beer. The rejection rate was 61 % in 2007, 56 % in 2008 and 48 % in 2009.

The reasons were: the insufficient cleaning of elements in the brewing and dispensing systems or the use of pitching yeast contaminated with bacteria. Nation-wide training courses for micro breweries have been offered since then and the assessment guidelines for microbiological standard values in beer – for micro breweries, in particular – have been reviewed.
Current tests focusing on the hygiene status of dispensing systems in pub breweries show clear improvements. The rejection rate in 2012 (Vienna, Burgenland, Styria) went down to 20 percent and to 13 percent in 2013 (Lower Austria, Upper Austria), compared to the results between 2007 and 2009.

The new assessment guidelines take into account the special brewing of beer in micro breweries, for the very first time. Such beer is usually not filtered or pasteurised and contains higher germ levels than beer brewed in large breweries. The microbiological-test scope encompasses the bacteria E. coli, coliform bacteria (fecal bacteria) and beer spoiling bacteria. The maximum levels of microbiological examinations have been adjusted to the technological situation at microbreweries without reducing the safety and sensory quality of the beer.

Links

Further Links and Informations

Official beer tests in Austria can be viewed in the Food Safety Reports: Lebensmittelsicherheitsberichten

The correct use of dispensing systems


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