Chlorine. Highly effective and relatively inexpensive, chlorine is the most commonly used chemical sanitizer agent. Typical chlorine compounds include liquid chlorine, hypochlorites, inorganic chloramines, and organic chloramines. These germicides attack microbial membranes, oxidize cellular protein, and inhibit cellular enzymes involved in glucose metabolism. Chlorine is effective against most bacteria, viruses, fungi, and bacterial spores. Chlorine solutions are highly corrosive and should not be used on surfaces that rust easily. The activity of chlorine is affected by such factors as pH, temperature, and soil load. In comparison with other sanitizers, chlorine is less affected by water hardness. Like most chemical sanitizers, the efficacy of chlorine can be diminished by the presence of food residues. Household chlorine should not be utilized in food facilities as it often contains substances and additives that are not approved for food use.
Quaternary ammonium compounds. Commonly known as quats or QACs, quaternary ammonium compounds are positively charged ions that are naturally attracted to negatively charged materials such as bacterial proteins. Effective against bacteria, yeasts, molds, and viruses, quats are active and stable over a broad temperature range. Usually odorless, non-staining, and non-corrosive, quaternary ammonium compounds are relatively nontoxic to users.
Iodophors. These act against bacteria, viruses, yeasts, molds, fungi, and protozoans. They attach themselves to sulfurs in proteins, which basically renders those proteins inactive. Iodophors have a continuous effect on microbial death due to a sustained-release effect. From a cost consideration, they are pricey and can stain some surfaces, especially plastics.
Peroxyacetic acids. Effective against most microorganisms, peroxyacetic acids (PAAs) are also efficient in removing biofilms. Normal cleaning and sanitizing methods, including chlorine use, usually do not eliminate disease-producing microorganisms that live in protective biofilm. Deemed as environmentally friendly, PAAs break down into acetic acid, oxygen, and water.
The Human Element
Proper sanitization occurs when specific chemical concentrations, time/temperature requirements, and water conditions are met. A lengthy list of factors, however, can affect the efficacy of chemical sanitizers, including:
- Concentration of the sanitizer (ppm)—too much can be toxic, too little is ineffective;
- Temperature of the sanitizing solutions—each has an ideal temperature for best effectiveness;
- Contact time with the surface or equipment to be sanitized—time needed to have a sanitizing effect;
- The pH and/or hardness of the water being used;
- Cleaning and rinsing—poor cleaning and rinsing can inactivate or reduce the effects of the sanitizer;
- Material being cleaned (plastic, metal, wood, glass)—some sanitizers are better on certain surfaces;
- Microbial load—the number of microbes on the equipment or surface initially; and
- Type of microorganism present—some microorganisms are more tolerant to certain sanitizers than others.
The knowledge of employees is another crucial factor that can greatly affect the efficacy of chemical sanitizers. Throughout the U.S., large numbers of food workers are trained on safe food handling practices, including cleaning and sanitizing procedures. Studies have revealed that training improves the food safety knowledge of industry employees. Unfortunately, this knowledge does not always transfer to the application of prescribed sanitary practices.
Consequently, it is imperative for companies to measure the effectiveness of sanitation training through employee testing, observing worker competencies up close in actual work settings, and reinforcing learning as necessary to achieve desired training outcomes.
Workers, at a minimum, should know how to mix sanitizers properly and how to test sanitizer concentrations at assigned temperatures. Without question, food employees are a critical human element in the appropriate use and optimal performance of chemical sanitizers.
Power of Concentration
Drawing upon 24 years of experience as a food microbiologist and researcher with Kraft Foods and the McKee Food Corp. among others, Carter states it is necessary to verify every aspect of sanitation programs, including sanitizer concentration.