Given what we now know about the opportunistic nature of food spoilage organisms, it is somewhat difficult to comprehend that processing plants and food service operations were once filled with food contact surfaces (e.g., wooden cutting boards, hard plastic sinks, and rubber conveyor belts) that greatly abetted their growth.
For even the most industrious sanitation crews of bygone times, cleaning and sanitizing a wide assortment of food contact surfaces were difficult, at best, to near impossible at worst.
Due to technological advances in hygienic food equipment design (clean in place), innovations in production equipment (i.e., the widespread implementation of stainless steel), and enhancements in preparation utensils, many contact surfaces are less prone to harbor potentially harmful food residues.
Nevertheless, the challenge of deterring the growth of bacteria, fungi, viruses, and other spoilage organisms on food contact surfaces is more pressing than ever in a heightened food safety-minded environment. Contaminated equipment and utensils have been cited as one of the leading risk factors most responsible for foodborne illness outbreaks in the U.S.
Local public health officials and federal regulators emphasize the importance of cleaning and sanitizing contact surfaces to prevent foodborne disease, and verification of the concentration of widely used chemical sanitizers through requisite testing. In addition to food plants, food service operations, and restaurants, contaminated food contact surfaces have been identified in a broad spectrum of institutions that prepare and serve meals, such as hospitals, military bases, long-term care facilities, supermarket delis, and schools.
The Food Safety and Inspection Service (FSIS), the meat and poultry oversight branch of USDA, states that the proper sanitization of contact surfaces is a fundamental and important task for food establishments. When performed correctly, according to FSIS, the sanitization of food contact surfaces: 1) decreases the chance of spreading foodborne illness from a food handler to a consumer; and 2) reduces the likelihood of contaminating previously safe food by destroying microorganisms found in food processing, preparation, and storage areas.
Gone in 30 Seconds
In accordance with sanitation standard operating procedures exercised across the food industry, food chemical sanitizers are used in tandem with detergents and water to kill potentially harmful microbes on food contact surfaces.
A food product contact surface is defined as a surface in direct contact with food residue, or where food residue can drip, drain, diffuse, or be drawn. Among the most frequently referenced contact surfaces in peer-reviewed scientific literature are cutting boards, knives, prep tables, sinks, scales, slicers, mixing bowls, food containers, and thermometers.
Food-grade chemical sanitizers from reputable suppliers, such as Ecolab, Inc., Birko Chemical Corp., ChemStation International, Diversey, and Zep Manufacturing, are approved by FDA for use in food facilities.
FDA-sanctioned sanitizers must destroy 99.999 percent of harmful bacteria within 30 seconds of a single application, be stable under a myriad of environmental conditions, and have low toxicity. Chemical sanitizers, which are registered through EPA, are reviewed for concentration efficacy, safety data, and product labeling information prior to being approved.
Noting it is difficult to overstate the importance of chemical sanitizers, Mark Carter, executive vice president of corporate development of Matrix Sciences, a full-service food testing and consulting laboratory that provides companies with analytical and business-based solutions, says the effective control of spoilage organisms is a “hidden gem” in strong and sustainable sanitation programs.
“The value of effective sanitizer use can sometimes get lost or overlooked in sanitation programs,” Carter proclaims. “It is inherently obvious, however, that chemical sanitizers—when applied at appropriate concentrations—are highly beneficial in helping industry stakeholders safeguard food products from disease-causing microorganisms.”
Scores of chemical sanitizers are utilized in food establishments. When choosing one for a particular food environment, users must weigh a host of considerations. Chief among them are the effectiveness at reducing microbial contamination in specific conditions, ease of application, need for rinsing, toxic/irritating properties, and compatibility with available water. The following section provides a brief synopsis of some of the most commonly used food-grade sanitizers.
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.
“Verifying sanitizer efficacy is a key process in managing a rigorous cleaning and sanitizing program,” he says. “Verification can be accomplished through various means, but when done correctly, it can help companies keep their sanitation systems under control.”
Federal, state, and local health regulations require companies to verify the concentration of chemical solutions through sanitizer test kits.
Through the efforts of companies like Micro Essential Laboratory (Hydrion) and other sanitizer kit suppliers, test strips have largely become the verification method of choice among chemical sanitizer manufacturers and users. Micro Essential supplies pH test papers, sanitizer test papers, and pH buffer standards to the global market.
Test strip kits, which are not interchangeable, contain detailed instructions (i.e., proper water temperature, contact time, correct level of sanitizer in solution) and color charts to determine accurate concentration measurements based on the type of chemical used. Generally, chemical manufacturers determine the concentration for effective sanitization.
When placed in the chemical solution, test strips produce a color change based on the amount of active chemical in the solution. Each color on the chart represents a different sanitizer concentration in ppm.
Pouring sanitizer solution into sinks and buckets can create foam. Usually, foam has a higher concentration of sanitizer and must be allowed to dissipate prior to testing unless a clear area in the solution can be found. Once the foam is gone, the test strip should be dipped directly into the solution and held still—without swirling or moving—for the correct amount of time based on the type of sanitizer being used. The test strip should then be immediately compared to the color chart located on the test strip dispenser to determine the concentration of the sanitizer.
Throughout the day, results should be documented, analyzed, and tracked as part of sanitation standard operating procedures.
For all types of sanitizers used in the food environment, the frequency of testing should be performed as needed to keep the water clean, to ensure effective sanitizer concentration, and aid in the entry of safe food into the consumer marketplace. Test kits have a maximum shelf life and should be discarded in accordance with expiration dates.
The strategic placement of technical information sheets and instructional posters in the workplace has been shown to be beneficial in reminding employees of the importance of following cleaning and sanitizing procedures. In a related vein, some chemical suppliers offer on-site training to assist operations with their sanitation efforts.
Sanitation programs must operate on all cylinders to protect the integrity of food from a diverse gamut of spoilage microorganisms. It has been said that proper sanitization is often the final—and definitive—step to ensure that safe food reaches consumers. This daunting maxim significantly raises the ante on food safety stakeholders to ensure their chemical sanitizers are performing at peak efficiency.
Williams is a food writer, editor, and marketer whose articles have appeared in numerous food industry publications. He previously served as communications manager (North America) at Mérieux NutriSciences. Reach him at firstname.lastname@example.org.