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Cleaning and Sanitation
Sanitizing Agents
The objective in sanitizing is to reduce the number of microorganisms present on a surface to acceptable levels. This is done with steam treatment or chemical sanitizers- alkaline and acid disinfectants.
Steam
Steam is still used extensively for sanitizing equipment, especially filling machines, and filters that are difficult to chemically sanitize. Some brewers favor steam for brewery sanitation on the grounds that chemical sanitizers can taint the beer with objectionable odors. To be effective, steam must be wet (not superheated) and free from air. Such treatment is effective, providing it is long enough to maintain a temperature of 100ºC for at least 15 to 20 minutes. However, heating equipment to above 60ºC for 20 minutes will eliminate most microbes. Steam is not suitable for certain types of cleaning. Where it is used, the plant equipment must be clean; otherwise, soil will bake onto the surface and cause sterility troubles later.
Alkaline Disinfectants
Sodium Hypochlorite: Among the chemical disinfectants, chlorine has been traditionally employed in breweries because of its relatively low cost and very powerful germicidal properties. It is commonly used in the form of sodium hypochlorite, known as household chlorine bleach, Clorox®, or chlorinated soda. The strength of all chlorinating agents is assessed in terms of their available chlorine.
Sodium Hypochlorite: Among the chemical disinfectants, chlorine has been traditionally employed in breweries because of its relatively low cost and very powerful germicidal properties. It is commonly used in the form of sodium hypochlorite, known as household chlorine bleach, Clorox®, or chlorinated soda. The strength of all chlorinating agents is assessed in terms of their available chlorine.
Hydrochlorous Acid: An effective form of chlorine is hydrochlorous acid, with a pH between 4 and 6. Most brewers, however, prefer to use chlorine at pH 7 or 8. Hydrochlorous acid is less effective at that pH range, but it is much safer to use. If the pH is too acidic, chlorine becomes corrosive to stainless steel and dangerous to people.
Chlorine Dioxide: Chlorine dioxide is an extremely good sanitizer at destroying spore-forming organisms. It is slightly more potent than chlorine as a disinfectant and can be used at lower concentrations than chlorine. Chlorine dioxide lacks the corrosiveness typical of chlorination. It is less likely to flavor the beer when properly used, having little or no phenolic taste or odor potential. Unlike sodium hypochlorite, no THM (trihalomethanes) or chlorophenols are produced when it is used.
Quaternary ammonium compounds, commonly referred to as "quats" or "QACs," are used extensively in breweries because of their stability and noncorrosiveness. They have rapid bactericidal action at very low concentrations but selective biocidal activity. QACs are efficient against gram-positive bacteria but less effective against gram-negative bacteria (35).
Acid Disinfectants
Hydrogen Peroxide: Hydrogen peroxide is used primarily as a sterilant, but it is also very effective in cleaning flexible tubing, filter cartridges, and housings. One of the advantages of using peroxides, compared with other sanitizers, is that there is no need for a final sterile water rinse following application. This is because the components in diluted solutions of peroxide break down to give water, active oxygen, and trace levels of acetic acid. Recommended temperature of use is 16ºC at a rate of 100 ppm.
Peracetic Acid: Peracetic acid is becoming increasingly popular since it leaves only traces of oxygen and acetic acid in the system. It is very effective at low temperatures and can be used as a sanitizer. Due to its completely nonfoaming nature, PAA is well-suited for CIP systems, but not necessarily in manual applications. This compound is considered extremely hazardous because it is reactive with many other chemicals.
Anionic Acids: Anionic acids are one of the fastest growing sanitizing groups in the craft brewing industry. They are chemicals composed of two functional groups – a lipophilic portion and a hydrophillic portion – which results in a negative charge. The negatively charged anionic acid sanitizers react with positively charged bacteria by attraction of opposite charges. Anionic acids are effective against all microorganisms at any temperature and are not affected by organic load.
Iodophores: The group of compounds called iodophores have a wide biocidal spectrum, react directly with the cell, and are not subject to immune species of yeast, bacteria, or molds. These are iodine-containing formulations 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.
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