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'''Quality Assurance''' refers to the process if developing standard operating procedures for proactively avoiding quality problems <ref name="Diffen">[https://www.diffen.com/difference/Quality_Assurance_vs_Quality_Control "Quality Assurance vs. Quality Control". Diffen website. Retrieved 03/28/2018.]</ref>. In the brewing industry, this includes avoiding off-flavors from contamination, dissolved oxygen in beer, fermentation and ingredient issues, etc. This article will focus on microbial contamination issues and methods, particularly in the area of sharing a space for both pure culture fermentation and mixed fermentation of beer.

While most microorganisms cannot survive in beer due to the hops, low pH, alcohol content, relatively high carbon dioxide, and shortage of nutrients, certain species are considered to be beer spoilage organisms due to their ability to form biofilms and survive in beer and make a potential impact on the beer's flavor by producing acidity, phenols, turbidity, and/or super-attenuation with just a few surviving cells. Adaption to the brewing environment also makes them more able to survive the harsh environment of beer. These species include [[Brettanomyces|''Brettanomyces'']] species, numerous [[Lactobacillus|''Lactobacillus'']] species, ''Pediococcus damnosus'', ''Pectinatus cerevisiphilus'', ''P. frisingensis'', ''Megasphaera cerevisiae'', ''Selenomonas lactifex'', ''Zymophilus'' spp., [[Saccharomyces#Saccharomyces_cerevisiae_var._diastaticus|''Saccharomyces cerevisiae'' var. ''diastaticus'']], and some species from the ''Candida'' and ''Pichia'' genera. Hop tolerant lactic acid bacteria make up the majority of contamination issues in breweries, with ''L. brevis'' making up more than half of the reported contaminations. In sour beers with a pH below 4.3, only the lactic acid bacteria, ''Brettanomyces'', and some wild ''Saccharomyces'' have the potential for unwanted growth, while beers with low alcohol, a small amount of hops, lower CO² volumes (cask ales and beers dispensed with nitrogen, for example), and higher pH (4.4-4.6) are the most susceptible to contamination. Other species of microbes do not grow in beer but can become contaminants earlier on in the brewing process (for example during kettle souring). These species include enterobacteria such as ''Clostridium'' species, ''Obesumbacterium proteus'' and ''Rahnella aquatilis'', and wild ''Saccharomyces'' that might not be able to grow in finished beer. Other species are considered "indicator" species because they do not directly cause spoilage of beer, but indicate that there is a hygiene problem. These include ''Acetobacter'', ''Gluconobacter'', and ''Klebsiella'' species, as well as aerobic yeasts, all of which usually don't have an impact when present unless oxygen is also present <ref name="Wirtanen_2001">[https://www.researchgate.net/publication/273439407_Disinfectant_testing_against_brewery-related_biofilms. Disinfectant testing against brewery-related biofilms. Erna Storgårds, Gun Wirtanen. 2001.]</ref><ref name="Bokulich_2018">[https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2012-0709-01 A Review of Molecular Methods for Microbial Community Profiling of Beer and Wine. Nicholas A. Bokulich, Charles W. Bamforth & David A. Mills. 2018.]</ref>.

Sources for contamination in breweries can occur as "primary" contaminations (yeast pitching, and brewhouse related contaminations), or as "secondary" contaminations (packaging and cellaring), as well as in tap systems. They are usually not sudden occurrences, but a result of continued growth of microorganisms in a problem area. Historically, re-pitching yeast was often a source of contamination, however, more recently this has become less of a source for contaminations due to better education and techniques. Typical sources for contamination also include unclean equipment such as thermometers, manometers, valves, dead ends, gas pipes, leaks in any part of the system (especially at heat exchangers), wort aeration equipment, and even worn floor surfaces. More than half of documented contaminations come from the packaging system. These are typically the sealer (35%), the filler (25%), the bottle inspector (10%), dripping water from the bottle washer (10%), and the environment close to the filler and sealer (10%). In regards to the environment as a source of contamination, this has been found to be from airborne contaminants near the filler and crowner. The higher the humidity and the more airflow, the more chances of airborne contamination. In tap systems at taverns, 'one-way' valves that are attached to kegs have been found to be a source of contamination, as well as the dispensing line <ref name="storgards_2000" />.

Bokulich et al. (2015) studied the microbial populations throughout a brewery (presumably Allagash) that produces clean beer, mixed fermentation sour beer, and spontaneously fermented coolship ale. They found that most of the microbes living in breweries were introduced from the ingredients such as malted barley and hops, and many populations were confined to specific rooms or areas within the brewery. Some species did spread to other rooms, presumably through human and insect vectors. Beer resistant lactic acid bacteria spread throughout the brewery (although more abundantly found near packaging equipment and fermenters that were filled with sour beer), but the clean beer was largely uncontaminated. Physical partitions and walls appeared to help inhibit the spread of microbes from room to room.

Microbes with hop tolerant genes were found more abundantly in the fermenter and packaging areas (filler heads, below the bottling line belt, packaging sink, and a keg faucet) compared to microbes found on pellet hops (which were determined to not be a source of contamination), kegs, or barrel bungs, and was associated with where beer was being processed, particularly mixed fermentation and spontaneously fermented sour beer <ref>[https://elifesciences.org/articles/04634 Mapping microbial ecosystems and spoilage-gene flow in breweries highlights patterns of contamination and resistance. Nicholas A Bokulich, Jordyn Bergsveinson, Barry Ziola, David A Mills. 2015.]</ref>.

Many microorganisms can form ''biofilms'' which is defined as a community of cells of one or more species that are attached to each other and/or a surface and are embedded in a matrix of extracellular polymeric substances (EPS), including polysaccharides and proteins, similar to a [[Pellicle|pellicle]]. Biofilms allow microbes to survive less vigorous cleaning and sanitizing regiments and chemicals and has become a concern in the food industry as well as in the brewing and winemaking industries <ref>[https://onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12087 The Paradox of Mixed‐Species Biofilms in the Context of Food Safety. Iqbal Kabir Jahid and Sang‐Do Ha. 2014.]</ref>. Biofilms most often form in the packaging system somewhere, but can also be found on side rails, wearstrips, conveyor tracks, drip pans, and in-between chain links <ref name="storgards_2000" />.

* [https://twitter.com/socialmicrobes/status/983764240254341125?s=04 Time lapse of biofilm formation.]

Some species of fungi and bacteria can form spores. Fungi form spores in order to reproduce sexually. Their sporulated forms are not a mode of protection from disinfectants and are therefore killed by normal sanitation methods. Bacteria form spores as a mode of survival. For example, some dangerous types ''Clostridium botulinum'' spores require 250°F (121°C) for 3 minutes to be killed, which is the requirement for canned goods <ref>[http://www.jfoodprotection.org/doi/abs/10.4315/0362-028X-45.5.466?code=fopr-site Differences and Similarities Among Proteolytic and Nonproteolytic Strains of Clostridium botulinum Types A, B, E and F: A Review. RICHARD K. LYNT*, DONALD A. KAUTTER and HAIM M. SOLOMON. 1982.]</ref><ref>[http://beerandwinejournal.com/botulism/ Chris Colby. "Storing Wort Runs the Risk of Botulism". Beer and Wine Journal Blog. 04/17/2014. Retrieved 04/04/2018.]</ref>. Spore-forming species of bacteria, however, are not considered beer spoilers <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2047716495256554/?comment_id=2047776558583881&reply_comment_id=2048688798492657&comment_tracking=%7B%22tn%22%3A%22R%22%7D Bryan Heit. Milk The Funk Facebook thread on yeast and bacteria spores and brewery hygiene. 04/04/2018.]</ref>. Thus, the challenge of killing yeast or bacteria spores is irrelevant in most beer and wine production. There are some extraneous brewing methods where bacteria spores should be considered, for example [[Wild_Yeast_Isolation#Safety|wild yeast isolation safety]], [[mold]] formation during fruit fermentation or barrel aging, and the [http://beerandwinejournal.com/botulism/ long storage of unfermented wort].

* Use the maximum concentrations, exposure times, and hottest temperatures (considering temperature limitations of plastics and glass) suggested by the manufacturers of any given cleaning/disinfectant product.

* Clean first using an effective cleaner, and then apply a disinfectant/sanitizer as a second step.

* The more surface area that equipment has, the more prone it is to biofilm formation. Horizontal surfaces are more prone than vertical surfaces to biofilm formation.

Several generalized procedures are used for limiting the number of unwanted microorganisms. These include acid washing yeast that is re-pitched (kills bacteria but not wild yeast), keeping beer cool (slows the growth of microbes in general), filtration (removes yeast), pasteurization (kills vegetative cells in the finished beer, but not spores - most beer spoilers are killed at 15 [http://wiki.zero-emissions.at/index.php?title=Pasteurization_in_beer_production pasteurization units (PU)] and all are killed at 30 PU using a recommended pasteurization temperature of 66°C ), and aseptic or hygienic packaging. Packaging systems should be frequently flooded with hot water between 80-95°C or saturated steam (every 2 hours in the summer and every 4 hours in the winter). UV light or disinfecting chemicals are also used. The filler and crowner should be disinfected frequently as well. Packaging in an aseptic room with HEPA filtration and higher air pressure within the room compared to outside, along with special clothing, is another method that larger breweries use to remain aseptic <ref name="storgards_2000" />.

Most brewing equipment should be designed for good hygiene. Pits and crevices should be avoided, and all surfaces should be smooth when possible. All equipment and pipelines should be self-draining. Valves are a typical source of contamination because they are not easily CIP'ed, especially plug valves and ball valves (although butterfly, gate, and globe valves are also difficult to CIP) <ref name="storgards_2000" />. Horizontal surfaces and wet surfaces are more prone to biofilm formation. In one study that compared biofilm formation in bottling lines versus canning lines, it was found that canning lines develop less microbial biofilms and contaminations than bottling lines due to not having rinsing stations, labeling stations, and simpler constructions than the bottling lines that were studied <ref name="Storgårds_2006" />. However, some canning lines cannot use caustic for cleaning or it is not common practice but use foaming agents instead which are less effective at removing biofilms (see [[Quality_Assurance#Efficacy_of_Cleaning_Agents|efficacy of cleaning agents below]]). The lack of use of caustic cleaners in canning lines has been identified as a source of contamination issues with [[Saccharomyces#Saccharomyces_cerevisiae_var._diastaticus|''Saccharomyces cerevisiae'' var. ''diastaticus'']] in canning lines <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1561762887185253/?comment_id=1791471917547681&reply_comment_id=2017381731623364&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Caroline Smith from Lallemand. Milk The Funk Facebook group post on diastaticus contamination. Feb 2018.]</ref>.

The goal of cleaning is to remove as much biomaterial as possible, while the goal of sanitizing is to reduce the population of viable microbes as much as possible and prevent them from growing on surfaces during the non-production time. It's been shown that chemical cleaners are better at removing biofilms than sanitizers and disinfectants, and sanitizers that kill cells in suspension may not be effective at killing cells within biofilms. Complete removal of unwanted microbes within biofilms can be achieved by first using a cleaning agent to remove the biomass followed by a sanitizing/disinfecting agent. CIP procedures may not be enough to remove biofilms without high turbulent flow with spray nozzles and the use of heat (low cleaning temperatures are not effective at removing biofilms). Chlorinated alkaline detergents were found to be the most effective at removing biofilms <ref name="Wirtanen_2001" />. Below is a typical CIP process according to [http://www.vtt.fi/inf/pdf/publications/2000/P410.pdf Erna Storgårds (2000)]; CIP processes at room temperatures are not adequate enough to remove biofilms, so use hot temperatures when applicable. Use the highest chemical concentrations recommended by the vendor. Also, the higher the velocity of the cleaning fluid through the system, the more efficient it is at removing biofilms:

* [https://www.facebook.com/groups/MilkTheFunk/permalink/1710242802337260/ Another MTF thread on sanitation.]

See the [[Barrel#Sanitizing|Barrel]] wiki page.

[[File:Wirtanen disinfectants.PNG|thumb|300px|Advantages and disadvantages of disinfectants in food processing. Source: [https://link.springer.com/article/10.1023/B:RESB.0000040471.15700.03 "Disinfection in Food Processing – Efficacy Testing of Disinfectants". G. Wirtanen and S. Salo. 2003.]]]

Sodium hydroxide (caustic), [https://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid EDTA (ethylene diaminetetra-acetic acid)], chlorinated disinfectants, and hydrogen peroxide-based disinfectants such as Pur-Ox from Birko or Lerasept-O from Loeffler are effective at breaking up biofilms when used in their highest recommended concentrations <ref name="Wirtanen_2001" /><ref>Brandon Jones. Private correspondence with Dan Pixley. 04/02/2018.</ref><ref>[https://www.reddit.com/r/TheBrewery/comments/6hqnvf/mtkettle_cleaning/dj0zd0s/ Levader on Reddit.com. "The Brewery". Retrieved 04/02/2018.]</ref>. Foaming agents that are often used in packaging lines for cleaning, however, might not be as effective. One study found that one foaming agent (VK10 Shureclean, which is sodium alkylbenzenesulphonate) required two times the maximum concentration that is recommended by the manufacturer to completely remove biofilms. In comparison, all of the sodium hydroxide (caustic) based cleaners that were tested were effective at completely removing biofilms in concentrations that were below the vendors' recommended maximum concentrations <ref>[https://link.springer.com/article/10.1007/s13213-010-0085-5#Bib1 Susceptibility of wine spoilage yeasts and bacteria in the planktonic state and in biofilms to disinfectants. Mariana Tristezza, António Lourenço, André Barata, Luísa Brito, Manuel Malfeito-Ferreira, Virgílio Loureiro. 2010.]</ref>. Peracetic acid (PAA) has also been shown to be effective against biofilms in the highest recommended concentrations but isn't as effective as the previously mentioned cleaners and should be used after a caustic cleaning cycle <ref>[https://www.researchgate.net/publication/273439407_Disinfectant_testing_against_brewery-related_biofilms Disinfectant testing against brewery-related biofilms. Storgårds, Erna & Närhi, Mikko & Wirtanen, Gun. 2001.]</ref><ref>[https://www.researchgate.net/publication/244994186_COMMERCIAL_SANITIZERS_EFFICACY_-_A_WINERY_TRIAL COMMERCIAL SANITIZERS EFFICACY – A WINERY TRIAL. Duarte, Filomena & López, Alberto & Alemão, Filomena & Santos, Rodrigo & Canas, Sara. 2011.]</ref>, but its effectiveness decreases below 20°C. Chlorine and iodine-based disinfectants destroy microbe at colder temperatures, however, they are less effective in the presence of wort or other residues. Chlorine-based disinfectants can cause pitting in stainless steel if left in contact for too long, and [https://ssbrewtech.zendesk.com/hc/en-us/articles/205602399-DO-NOT-USE-BLEACH-OR-CHLORINATED-CHEMICALS- some stainless steel manufacturers] recommend not using chlorine-based disinfectants at all (refer to your equipment and chemical manufacturers). Hot water is one of the most effective disinfectants, however, dry heat is not as effective at killing bacteria (one strain of ''L. brevis'' was able to withstand 80°C dry heat for 60 minutes) <ref name="Wirtanen_2001" />. Dry heat at higher temperatures will sterilize at 170°C for 1 hour or 190°C for 12 minutes and can be used to sterilize many metal and glass instruments. Flaming surfaces kills within seconds <ref>Private correspondence with Dr. Bryan Heit by Dan Pixley. 04/12/2018.</ref>.

'''Five Star Star San'''