Brewery Cleaning And Sanitation
Once deposits and debris are removed and surfaces are visibly clean, the equipment can then be sanitized. Sanitizing agents (often called disinfectants) are used to reduce the number of microorganisms to acceptable levels in the brewery. The single most important precondition for successful sanitizing is an effective cleaning program. Any residual deposits remaining can protect microorganisms from contact with the sanitizer, thus reducing their effectiveness. Sanitizing may be accomplished by physical methods (e.g., hot water or steam) or through the use chemical sanitizers.
Hot Water and Steam
Ideally, hot water used for sanitation should be at least 82 degrees C (180°F) at discharge, circulated or held for a minimum of 10 to 15 minutes. If you cannot maintain the higher temperature, the time should be increased (i.e., 20–25 minutes) with a minimum temperature of 179 degrees C (175°F). It is critical that time and temperature be monitored carefully to ensure reliable results. Effective hot-water sanitation of pasteurized storage tanks is difficult and may cause damage to some tanks if done without care.
As opposed to thermal sanitizing, chemical sanitizers do not require heat to kill microorganisms. Issues to consider when using disinfectants include the sanitizer’s range of microbial activity and effectiveness on certain microorganisms, longevity and residual effectiveness, specialized equipment needed, related energy costs, worker safety, and possible reactions with other chemicals or beer product. Chemical sanitizing generally involves either immersing the object in a sanitizing solution for a specific amount of time or spraying/wiping the object with the solution and allowing it to air-dry.
Quaternary ammonium compounds, commonly referred to as QUATs or QACs, are used extensively in breweries because of their stability and non-corrosiveness. They have rapid bactericidal action at very low concentrations but selective biocidal activity. Gram-positive bacteria (Oenococcus, Pediococcus, and Lactobacillus) are most sensitive, whereas Gram-negative bacteria (Acetobacter and Gluconobacter) are less so. Quaternary ammonium compounds can be used on a wide variety of brewery equipment, including: presses, destemmer-crushers, tanks, fittings, transfer hoses and pumps, filters, walls, and floors.
Peroxyacetic acid (peracetic, PAA) has been known for its germicidal properties for a long time. Peroxyacetic acid is gaining popularity as a sanitizing agent in the beer industry for its broad microbicidal capacity, and rapid, on-contact efficacy under a range of conditions. It can be used to sanitize a range of surfaces and equipment, including tanks, pumps, lines, and filters, and is non-corrosive to stainless steel at the dilute usage concentrations. It is suitable for use in a final CIP rinse; no further rinsing is required.
Ozone is one of the most potent sanitizers available and is finding increased use in the beer industry. Ozone is effective against bacteria, fungi, and viruses. Unlike chemical sanitizers, ozone oxidation leaves no harmful or foul byproducts and residue, only oxygen. Because it’s highly reactive and unstable, ozone doesn’t persist—any ozone not instantly consumed by contact oxidation of organics quickly reverts to oxygen. This makes ozone perfect as a final, no-rinse sanitizer. With no persistence, ozone requires no special disposal system. Neither pH nor temperature affects the activity of this sanitizer. Like many sanitizing agents, ozone is often combined with other technologies to increase its efficacy.
Chlorine dioxide’s properties make it an ideal choice for most brewery operations. Chlorine dioxide does not form trihalomethanes or chlorophenols, which is very important to the brewer because these compounds are extremely detrimental to beer, not to mention the toxicity to humans or the environment. Chlorine dioxide is a strong oxidizing agent. Chlorine dioxide possesses broad spectrum antimicrobial capabilities. It is effective against a variety of beer spoilage organisms, including bacteria, yeast, and mold. It is able to penetrate the cell membranes of microorganisms, rendering it more effective than chlorine.
Iodophors are considered to be broad spectrum sanitizer with demonstrated effectiveness against a variety of bacteria, yeasts, and molds. Iodophors are iodine-containing formulations are usually composed of elemental iodine, a surfactant, and an acid such as phosphoric acid. The surfactant reduces the staining and corrosive properties of iodine, which is stated to be a more effective sanitizer than chlorine at comparable concentrations. Though not as effective as other sanitizing agents, its major advantage is that it evaporates directly from solution to gas when used in proper proportions, and hence leaves no residues and, as some manufacturers suggest, requires no rinsing.
Acidulated Sulfur Dioxide
Acidulated sulfur dioxide may be used as an effective sanitizing agent especially for hoses. Because the antimicrobial activity of sulfur dioxide is pH dependent, the sanitizing agent (100mg/L sulfur dioxide or 200mg/L potassium metabisulfite) is usually made up in acidulated solution by inclusion of 3 g/L citric acid.
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