There are three commonly used methods of sanitation: Thermal, radiation, and chemical. The Environmental Protection Agency (EPA) regulates sanitizers for all applications, from health care to food manufacturing. To be an EPA-registered sanitizer (whether thermal, radiation, or chemical) for a food contact surface, test results for a product must show a bacterial reduction of at least 99.999 percent over the parallel control count within 30 seconds for the bacteria E. coli and S. aureus.
Obviously this is a big subject, so I am going to focus on chemical disinfection, a very common and effective way to sanitize equipment or other surfaces. Chemical sanitizers to be used on previously cleaned food contact surfaces require a 5-log reduction of S. aureus and E. coli and are registered by EPA for efficacy.
A sanitizing solution consists of a chemical compound that is mixed with water and applied to a surface. This chemical attacks and kills microorganisms present on the contact surfaces. The most common chemical compounds utilized as effective sanitizers are chlorine, iodine, quaternary ammonium (known as “QUATS”), and peroxide.
Chemical sanitizers available for use in food processing vary in their chemical composition and their activity, and understanding the individual characteristics of each chemical is the key in choosing the best sanitizer for a particular job. The ideal sanitizer has broad-spectrum microbial destruction properties, with a uniform rapid kill against vegetative bacteria, yeasts, and molds. It must also be effective in the presence of organic matter, detergent residues, water hardness, and pH variability.
The ideal sanitizer is also nontoxic and nonirritating, soluble in water, noncorrosive, has a low level of acceptable odor or is odorless, and is stable in both its concentrated form or at its diluted usage level. Application methods vary from product to product, and recommended directions for use are listed on each sanitizing product. Sanitizers should be easy-to-use, readily available, and inexpensive.
Chlorine Sanitizers. These sanitizers are commonly utilized in the food industry because they are inexpensive, fast acting, and effective against a variety of microorganisms. There are several different chlorine compounds that are used, including hypochlorite, organic and inorganic chloramines, and chlorine dioxide. Chloramines are formed from the addition of ammonia to hypochlorous acid, forming chloramine and water.
The term “available” or “free” chlorine is used in evaluating a chlorine sanitizer’s level of effectiveness. “Free chlorine” is the amount of chlorine available to act as a sanitizer. One thing to remember, however, is that chlorine will bind to organic soils or evaporate and, as a result, becomes unavailable in the sanitation process. For example, residual soap will negate a chlorine solution’s sanitizing effectiveness, underscoring the importance of the cleaning process that precedes the disinfection process.
Municipalities that treat drinking water with chlorine target a minimum residual of 1 part per million, or ppm, of free chlorine. Most public spas and hot tubs must contain 1.5 to 3 ppm of free chlorine. In the food industry, a chlorine solution of 50 ppm or less is not considered a sanitizer, so 50 ppm of chlorine is the minimum requirement imposed on a sanitizer for a food facility. But remember—too high a concentration of free chlorine results in chlorine residues. Therefore, generally, the maximum usage level for equipment (without rinsing) is 200 ppm.
Chlorine efficacy is both temperature and pH-sensitive. At high water temperatures, chlorine quickly evaporates, rendering the solution ineffective. The pH also affects a chlorine solution’s efficacy, with chlorine solutions being most effective at pH levels around 6.5. At a lower pH, the chlorine solution can be corrosive to materials and surfaces. Chlorine’s effectiveness drops very quickly as pH rises above neutral pH of 7. Because chlorine is corrosive and a skin irritant, its use poses potential health hazards.