Brewers are an incredibly stubborn lot. By continuing you agree to the use of cookies. Unlike iodophor, however, the amount used is typically not as critical both in terms of microbial reduction and flavoring beer. For vessels that will be refilled with beer within a few hours, chlorine dioxide works best to give a quick kill without flavoring the beer. Conversely, chlorine dioxide is ideal for sanitizing after the cleaner has been rinsed. Brewers know that carbon dioxide is more stable at colder temperatures (known as Henry’s law). The best known brand is Clorox. The recommended concentration for disinfection has been 600-800 ppm of chlorine bleach and 50 to 200 parts per million (ppm) for sanitizing. Reuse is not typically recommended because once the chlorine dioxide is generated, the solution begins to lose concentration. The sodium chlorite is then added to the acidified water to generate chlorine dioxide. Stainless steel types 304 and 316 corroded rapidly when exposed to the acidified chlorite solution. Eye contact is irritating, however, and an eye wash with cold water for 15 minutes is recommended should the sanitizer come in contact with the eyes. 5.25% Sodium Hypochlorite is cheap, usually costing around one dollar per gallon at your local supermarket. Quantitative measurement of chlorine dioxide can be achieved by using a chlorine dioxide test kit, which is available from laboratory suppliers, such as Hach or LaMotte. For brewers to try sanitizing with chlorine dioxide, a small pilot batch or system should be tested. Keeping the Workforce Safe During the COVID-19 Pandemic. Chlorine dioxide is, by and large, less irritating than most sanitizers. The acidification of water to drop the pH to 4.5-5 then adding the sodium chlorite ensures that the solution does not become too acidic. In sanitizing (and especially post-rinse sanitizing) where the beer and “chemical” actually have the possibility of coming in contact with one another, a huge leap of faith is required on the part of the brewer to try a different approach. Chlorine dioxide removes phenolic tastes and odors from water and does not form trihalomethanes or chlorophenols. Chlorine dioxide (ClO2), like iodophor, is very effective at destroying spore forming organisms at low active parts per million (ppm) levels and does not flavor beer when used properly. This method works well for small volumes of water or with soft water. The symptoms can begin to show long after the exposure has taken place and can remain for a long time. One sanitizer was an acidified solution of dilute sodium chlorite at pH 2.7; the other sanitizer was dilute chlorine dioxide (about 15 ppm) in tap water. 5. So it is with chlorine dioxide. Spore-forming organisms are notorious for becoming progressively immune to sanitizers (especially chlorine bleach) when used continuously for weeks and months at low ppm levels. For best results, use the cold tap water and keep the temperature of the solution below 80 degrees F. Do not reuse the solution. Federal exposure limits of chlorine dioxide are published in the MSDS. Chlorine dioxide was used to treat the US Senate Building after the anthrax attack. The 8-h time weighted average for chlorine dioxide is 0.1 ppm. Do not use hot water when making chlorine dioxide solutions. The acidification of sodium chlorite, NaClO2 at moderate acid pH (5 – 6) to generate chlorine dioxide gas, ClO2, has a mechanism as follows(2): 5NaClO2 + 4H+ —-> 4ClO2 + 4Na+ + Na+Cl- + 2H2O. This is preferred due to in some countries, it is been regulated that it will minimize the use of rinsing if you use that concentration. Inhalation of chlorine dioxide gas causes coughing, a sore throat, severe headaches, lung oedema and bronchio spasma. Basically, however, it comes down to three questions: These are the questions that need to be answered by the brewer before jumping in with both feet. Proper measures need to be taken not to overuse any sanitizer. Chlorine dioxide is also used to remove cyanides, sulfides, aldehydes and mercaptans from water. Chlorine dioxide relies on oxygen chemistry (oxidation) to kill organisms. Because fibers from the boxes can be electrostatically deposited inside the bottle, many breweries rinse the bottles just prior to being filled. Chlorine dioxide can induce a total and irreversible elimination of biofilm constituents (fixed bacteria, proteins and polysaccharides). Studies have shown that it produces as high as a 6-log reduction. That’s great, you say, but what is chlorine dioxide? Both mechanisms are extremely quick, but leave little residual protection. Rinse with phosphoric acid to neutralize the caustic and remove beerstone (calcium oxalate). Conversely, chlorine dioxide is ideal for sanitizing after the cleaner has been rinsed. Based on 100 grams of sodium chlorite concentrate: 8.3 g NaClO2 x {(67.45 g ClO2 ) / (90.45 g NaClO2 )} x 0.97 yield = 6.0 g ClO2. In the case of sodium hypochlorite bleach, they are correct. A 50-100 ppm chlorine dioxide solution should have little or no odor and that is why flavoring is not a problem. Homebrewers are familiar with sodium hypochlorite (NaOCl), 5.25%. As shown in Table 1, about one tablespoon (1/2 fluid ounce, 15 ml) of typical chlorine bleach per gallon of water is the maximum that should be used for sanitizing … Chlorine dioxide cannot be stored for too long, because it slowly dissociates into chlorine and oxygen.It is rarely stored as a gas, because it is explosive under pressure. Spanish flu (A/H1N1), a pandemic oc- At more aggressive pH (4.5 or less), chlorite becomes chlorine dioxide on a more one-to-one basis involving several mechanisms. For a 1.75% titratable iodine concentrate, no more than 1 (one) fluid ounce per 5 gallons of water should be used to achieve 25 ppm active. Overusing iodophor serves only to flavor beer and does not offer any additional microbiocidal effect. The short-term exposure level for chlorine dioxide in the air is 0.3 ppm. Chlorine dioxide near neutral pH 7.2 was noncorrosive to both type 304 and 316 stainless steels at a concentration of 100 ppm during 10 d of continuous exposure. 4. For bleach with a higher concentration, contact your chemical supplier. If there is more time between sanitizing a refilling the vessel with beer such as a day or weekend, iodophors offer residual protection that chlorine dioxide cannot. Therefore, post-rinse sanitizing equipment and bottles is not recommended with hypochlorite bleach. The taste associated with beer that has been flavored with iodophor can be termed medicinal or phenolic, (sort of like a bandaid), metallic or “tinny”. Activate only the amount of sodium chlorite needed for a given application, such as sanitizing a fermenter, then discard the solution when you are done. Copyright © 2020 Elsevier B.V. or its licensors or contributors. 2). Once a system for cleaning and sanitizing is established that actually works and a quality beer is produced, it is tough for change to occur.