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Five Star Chemicals product Star San is a popular acid anionic sanitizer sold to homebrewers because of its relative safety and ease of use. Claims that acid anionic sanitizers are not effective at killing yeast have been made on various internet forums <ref>[https://www.homebrewersassociation.org/forum/index.php?topic=24447.msg312961#msg312961 User 'S. cerevisiae'. American Homebrewers Association forums. 10/05/2015. Retrieved 04/11/2018.]</ref><ref>[https://www.homebrewersassociation.org/forum/index.php?topic=4576.msg52894#msg52894 User 'richardt'. American Homebrewers Association forums. 11/15/2010. Retrieved 04/11/2018.]</ref><ref>[https://community.diybeer.com/topic/9709-starsan-not-effective-against-wild-yeast-and-molds/ Coopers Community Forums. Post by user 'Christinas1'. 09/08/2016. Retrieved 05/23/2019.]</ref>. These claims are cited in various food science pamphlets, blogs, and websites, and appear to be based on the food science textbooks, "Principles of Food Sanitation," by Norman G. Marriott and Robert B. Gravani (2006) and "Basic Food Microbiology" by George Banward (1989), which contain conflicting information about the effectiveness of acid anionic sanitizers. Neither of these textbooks contain experimental data nor references to experimental data. The statements in these books conflict with each other. Marriott and Gravani claim, "(Acid anionic sanitizers) have limited and varied antimicrobial activity (including poor yeast and mold activity)... The antimicrobial effect of acid anionics appears to be through reaction of the surfactant, with positively charged bacteria by ionic attraction to penetrate cell walls and disrupt cellular function." Banward's claims of acid anionic sanitizers are, "Advantages: Active against a wide spectrum of microorganisms including thermodurics, controis phage and most yeast strains. Disadvantages: Slow activity against sporeformers, not effective in destruction of most spores." Furthermore, the provided explanation, which is that acid anionic sanitizers supposedly don't work effectively against yeast and molds is because acid anionic sanitizers are negatively charged and yeast are also negatively charged yet bacteria is killed because it is positively charged, is biologically incorrect ([https://etd.ohiolink.edu/pg_10?0::NO:10:P10_ACCESSION_NUM:osu1250193404 this masters thesis] appears to be the source of this incorrect information). According to [https://www.youtube.com/watch?v=0JC9n50RdVo Dr. Bryan Heit of Sui Generis blog], both yeast and bacteria have negatively charged cell walls, and this fact has been well established in microbiology since the 1940's (Dr. Heit has published several [https://scholar.google.com/citations?user=8yxqYNgAAAAJ&hl=en&oi=ao peer-reviewed scientific studies on cell wall polarity]).
Star San has only been officially tested by Five Star Chemicals against the pathogenic bacteria species ''E. coli'' and ''S. Aureus'', which is the minimum baseline required by the EPA to be labeled a "sanitizer" <ref>[https://www.homebrewersassociation.org/forum/index.php?topic=31537.msg409346#msg409346 Conn, Denny. American Homebrew Association forums. 04/08/2018. retrieved 07/09/2018.]</ref>. While we are not aware of any publicly available published studies on the efficacy of StarSan to kill yeast, several studies with other acid anionic sanitizers have confirmed that they are effective against yeast. Lee et al. (2007) found that an acid sanitizer very similar to Star San that uses citric acid instead of phosphate but the same surfactant (sodium dodecylbenzene sulfonate) took 5 minutes to kill ''Saccharomyces cerevisiae'', ''E. coli'', and ''Listeria innocua'' at room temperature (some species were killed faster than others with the ''E. coli'' actually being more resistant than the yeast), and one minute if the sanitizer was heated to 40°C on both metal and LDPE plastic (they compared the acid anionic sanitizer to 35% hydrogen peroxide, which killed all organisms with 15 seconds, indicating that this acid anionic sanitizer is effective at killing yeast, but it takes longer than a stronger chemical such as hydrogen peroxide). This study did not make mention of biofilms, however, the cultures were allowed to grow and dry overnight which could have allowed for biofilm formation <ref>[https://onlinelibrary.wiley.com/doi/full/10.1111/j.1750-3841.2007.00496.x Efficacy of Two Acidic Sanitizers for Microbial Reduction on Metal Cans and Low-Density Polyethylene Film Surfaces. J. LEE, M.J. GUPTA, J. LOPES, AND M.A. PASCALL. 2007.]</ref>. Five star Star Chemicals [httphttps://www.fivestarchemicalsbsgcraft.com/wp-contentResources/Craftbrewing/PDFs/uploadsProduct_Spec_and_Data_Sheets/Star-San-HB4Product_Spec_Sheets/StarSan_Tech.pdf also recommends 5 minutes of contact time with Star San]. Winniczuk et al. (1997) found that three phosphoric acid anionic sanitizers ("CS-100" and "CS-101-lf" by Chemical Systems of Florida, and "Clear-Clean" by Pelican Brand) were less effective at killing yeast than bacteria in the timeframe tested (1 minute contact time), but they were still effective at killing yeast at high concentrations (peracetic acid also required a higher concentration to kill yeast than bacteria). However, one of the acid anionic sanitizers tested was more effective than the other two, indicating that the chemical makeup of the particular acid anionic sanitizer has an impact on how effective it is as a sanitizer relative to other acid anionic sanitizers. Additionally, they found that peracetic acid, iodophor, and chlorine dioxide required less concentration than the acid anionic sanitizers to be effective (again, tested at 1 minute exposure time) <ref>[http://lp7lc5er8n.scholar.serialssolutions.com/?sid=google&auinit=PP&aulast=Winniczuk&atitle=Minimum+inhibitory+concentrations+of+antimicrobials+against+micro-organisms+related+to+citrus+juice&id=doi:10.1006/fmic.1997.0103&title=Food+microbiology&volume=14&issue=4&date=1997&spage=373&issn=0740-0020 Minimum inhibitory concentrations of antimicrobials against micro-organisms related to citrus juice. P.P Winniczuk, M.E Parish. 1997.]</ref>.
See [https://www.facebook.com/groups/MilkTheFunk/permalink/1436419659719577/ this MTF thread] for a more extensive explanation of why skepticism should be applied to the claim that acid anionic sanitizers are not effective at killing yeast.
# For non-circulated, soaking, use 6 to 8 ounces per gallon of 180°F water (if using this product on plastics, heat the water that is mixed with the PBW to be as hot as the manufacturer of the plastics recommends), and soak overnight. Note that there have been reports of high concentrations of PBW breaking down PET bottles over time when soaking <ref>[https://www.homebrewtalk.com/forum/threads/pbw-and-plastics.521708/ Homebrewtalk thread reporting PBW breaking down PET bottles. 03/25/2013.]</ref>. For example, BetterBottle™ recommends using 5 grams per liter of 125°F water (0.67 ounces per gallon, or one tablespoon per gallon) of PBW and cleaned with agitation/circulation instead of soaking. They also recommend using an enzymatic cleaner such as Seventh Generation Free and Clear Natural 2X or Super Pro-zyme Enzymatic Cleaner instead of PBW <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/2104526149575588/ Better Bottle Cleaning and Sanitizing web article; downloaded from Archive.org.]</ref>.
# Rinse thoroughly with hot water (cold water may not remove some of the residual chemicals).
Alternatives to PBW include:
* [https://www.nationalchemicals.com/craftmeister/ CraftMeister Alkaline Brewery Wash.]
* [https://www.google.com/search?client=firefox-b-1-d&q=pbw+vs+oxiclean Unscented Oxiclean.]
'''See Also'''
While the VBNC state has mostly only been studied in detail for bacteria, it has also been suggested that this state is also possible with eukaryotes (yeast). It has been reported that although there are many methods for detecting ''Brettanomyces'' in winemaking, there are cases when ''Brettanomyces'' is not found using culturing techniques, but years later have still infected wine. Agnolucci et al. (2010) found that sulfur dioxide induces the VBNC state in 7 ''Brettanomyces'' strains isolated from wine at concentrations of 0.2 mg/L (molecular SO<sub>2</sub>) for 5 out of the 7 strains to 0.4 mg/L for the other 2 strains after 24 hours of incubation in a synthetic wine medium that was supplemented with various amounts of sulfur dioxide. At 0.4 mg/L they found that all but one strain had 0% culturable cells, and 4-26% VBNC cells depending on the strain. At 0.8 mg/L, no strains had culturable cells, but they all had at least 4.6-17% VBNC cells (percent of the original number of cells before being exposed to the sulfur dioxide). Even at 1 mg/L of sulfur dioxide levels, there were 2.9-15% VBNC cells, depending on the strain (the ability for the ''Brettanomyces'' to remain viable at 1mg/L of sulfur dioxide might have also been due to the pH only being 3.5, and ethanol only being 13%). They also found that 2.1 mg/L was required to reduce the VBNC state of cells to zero after 55 days of incubation and limit the amount of ethyl phenols produced by ''Brettanomyces''. They reported that trypan blue was the best method for detecting VBNC cells <ref>[https://www.sciencedirect.com/science/article/pii/S0168160510003958?via%3Dihub Sulphur dioxide affects culturability and volatile phenol production by Brettanomyces/Dekkera bruxellensis. Agnolucci M, Rea F, Sbrana C, Cristani C, Fracassetti D, Tirelli A, Nuti M. 2010. DOI: https://doi.org/10.1016/j.ijfoodmicro.2010.07.022.]</ref>.
The Agnolucci et al. (2010) study did not provide a method or data for resuscitating the VBNC ''Brettanomyces'' cells so that they can again divide and grow colonies, and this has been criticized because resuscitation of VBNC cells is considered an important aspect of strengthening the conclusion that the cells are indeed VBNC. Serpaggi et al. (2012) found similar results with using 0.8 mg/L of molecular SO<sub>2</sub>, which resulted in all ''Brettanomyces'' cells from one wine strain to not be culturable on YPD after being incubated in synthetic wine medium that was supplemented with SO<sub>2</sub> for 2 days, while the viability of the cells remained high for as long as 11 days (they did not check viability after 11 days, and the viability count remained constant from day 2 to day 11; viability was determined by staining with fluorescein diacetate which stains when certain metabolic esterase activity is present). They were able to resuscitate the cells by adding NaOH to the media to bring the pH up from 3.5 to 4.0 in order to effectively eliminate the molecular sulfur dioxide (molecular SO<sub>2</sub> is the only form of SO<sub>2</sub> that is significantly effective at inhibiting microbes, and it is only stable at very low pH's). They noted that VBNC cells were about 20% smaller in size than culturable cells. The cells in the VBNC state did not produce 4EG phenol but did produce a very small amount of 4EP phenol <ref>[https://www.ncbi.nlm.nih.gov/pubmed/22365358 Characterization of the "viable but nonculturable" (VBNC) state in the wine spoilage yeast Brettanomyces. Serpaggi V, Remize F, Recorbet G, Gaudot-Dumas E, Sequeira-Le Grand A, Alexandre H. 2012. DOI: 10.1016/j.fm.2011.12.020.]</ref>. It has also been demonstrated that the presence of minerals and vitamins, as well as p-coumaric acid, can assist in resuscitating so-called VBNC cells of ''Brettanomyces'' <ref>[https://www.mdpi.com/2306-5710/9/3/69 Chandra M, Branco P, Prista C, Malfeito-Ferreira M. Role of p-Coumaric Acid and Micronutrients in Sulfur Dioxide Tolerance in Brettanomyces bruxellensis. Beverages. 2023; 9(3):69. https://doi.org/10.3390/beverages9030069.]</ref>.
It is worth noting that the VBNC state in ''Brettanomyces'' has not been tested against a higher concentration of SO<sub>2</sub> (for example when wineries use much higher concentrations of SO<sub>2</sub> solutions as a sanitizer), other chemical sanitizers, and pasteurization-level temperatures. For example, it has been proposed that steaming barrels in order for them to reach 140°F (60°C) for 20 minutes is enough to sanitize them (see [[Barrel#Sanitizing|Barrel Sanitizing]] for more information). However, Nunes de Lima et al. (2020) inoculated wines with various strains of ''Brettanomyces'' after raising the pH of the wine to 3.8, which rendered the amount of free SO<sub>2</sub> in the wines completely ineffective, and many of the strains entered a VBNC state. This indicates that other unknown factors can induce a VBNC state in ''Brettanomyces''. It has been documented that other factors, such as nutrient starvation, extreme temperatures, osmotic pressure and oxygen, has caused a VBNC state in other microorganisms (VBNC has been mostly studied in bacteria) <ref name="Nunes de Lima 2020">[https://www.sciencedirect.com/science/article/abs/pii/S0740002020302069 Survival and metabolism of hydroxycinnamic acids by Dekkera bruxellensis in monovarietal wines. Adriana Nunes de Lima, Rui Magalhães, Francisco Manuel Campos, José António Couto. 2020. DOI: https://doi.org/10.1016/j.fm.2020.103617.]</ref>.
* [http://masterbrewerspodcast.com/115-todays-challenges-in-beer-quality MBAA Podcast interview with Mary Pellettieri, author of "Quality Management: Essential Planning for Breweries".]
* [https://www.masterbrewerspodcast.com/045 MBAA Podcast interview with Eric Jorgenson about his approach to microbiology and his quick reference guide of significant bacteria found in the brewery environment.]
* [https://www.masterbrewerspodcast.com/271 MBAA Podcast interview with Lauryn Rivera and Tess Downer about Comprehensive Quality at Odell's.]
* "Quality Management: Essential Planning for Breweries" by Mary Pellettieri (Brewers Publications), 2015.
* "Illustrated Guide to Microbes and Sediments in Wine, Beer & Juice" by Charles G. Edwards (WineBuggs LLC), 2005 - A microscope companion book that includes over 30 different species of yeast, bacteria and mold commonly associated with beverages, as well as frequently encountered sediments.