The application and use of sanitizers in our industry is widespread, and it goes beyond the traditional application during the normal cleanup and sanitation process. Sanitizers are now used as an agent in process control to reduce risk and provide a greater level of consumer protection from pathogen contamination.
The war on pathogens has changed the focus of sanitizer usage from shelf-life control to pathogen control. Sanitizer usage as a process-control agent in a zero-tolerance landscape presents many challenges.
Let’s start by examining the difference between a disinfectant and a sanitizer.
Both types are regulated by the Environmental Protection Agency (EPA). The EPA rules include testing, claims and direction for use. 1
A disinfectant must completely eliminate all the organisms listed on its label and may include viruses and fungi.
Sanitizers do not need to eliminate one hundred percent of all organisms to be effective. Fungi or viruses are not included in a sanitizing claim. For food contact surfaces, a sanitizer must reduce the bacterial count by 99.999%.
Conditions of Use
Disinfectants and sanitizers are intended to be used on hard, non-porous, environmental surfaces such as walls, floors and equipment. A disinfectant can be used on a food contact surface, but the surface needs to be rinsed with potable water after being disinfected. A food contact sanitizer should not be rinsed after sanitizing a food contact surface. A food contact sanitizer is designed to function as the final rinse on food contact surfaces.
Sanitizers are defined as incidental food additives under the Federal Food, Drug, and Cosmetic Act, (21 U.S.C. 201), and require establishment of a food additive tolerance.
Chlorine-bearing chemicals must be validated with the AOAC Available Chlorine Germicidal Equivalent Concentration Method. The requirements are for one test on each of 3 samples, from 3 different batches, one of which is at least 60 days old. The test organism is S. typhi. Test results must show chlorine concentrations of 50, 100, and 200 ppm of available chlorine.
Efficacy testing of quaternary ammonium compounds (quats) is similarly conducted by the AOAC Germicidal and Detergent Sanitizers Method. The test organisms are E. coli and S. aureus. The minimum concentration of the product which provides a 99.999% reduction in the number of microorganisms within 30 seconds is the minimum effective concentration.
The above examples describe the application of sanitizers on clean, hard, impervious surfaces. In many process-control applications, the surface to be treated is not always clean. Likewise, the operational application of sanitizers to contact and non-contact surfaces as well as product is not required nor technically expected to have a 99.999% or 5 log kill (Figure 1).
This is why validation tests need to be conducted to determine effectiveness of the application.
Figure 2 is an example to help define and describe some of the terms used in measuring the effectiveness of sanitizers. If a sanitizer applied to a process has a reported log kill value of Log 3 (It kills 99.9% of the bacteria present) these are the results.
Let’s assume 1,000 CFU/sq. in. and the surface area to be treated is 100 sq. in. This means there are 100,000 CFU/100 sq. in.
If the sanitizer treatment has a 3 log reduction potential measured by a validation test, then 100 CFU/100 sq. in. would remain. This is equivalent to 1 CFU/sq. in.
So out of 100 sq. in., each square inch would theoretically have 1 bacteria present. To effectively remove the contaminating organisms, the initial count must be lower or the sanitizer reduction potential must be higher.
The use of sanitizers as an in-process control factor is best defined as a hurdle in the process-control system. Sanitizers, when used as an in-process control hurdle, do not always exert absolute control over the process as a HACCP critical control point (CCP) is intended. Hurdles reduce risk and exert some control. The level of control attained is measured with a validation study.
Many in-process applications of sanitizers are designed to prevent or minimize the movement of the organism as it travels from transfer point to transfer point on floors, equipment, material, people and unfortunately products. Everything that moves or is moved inside the plant is a potential transfer agent for a microbiological hitchhiker. Chemical sanitizers act as hurdles in these microbial pathways or transfer vectors. In many situations requiring control, or when one is forced with a zero tolerance, multiple hurdles are often required to exert the level of control desired.
The following link defines applications of sanitizers for indirect usage (21CFR178.1010): http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=178.1010
The sanitizers cited are approved for the uses stated by FSIS. The usage level or upper concentration limit is defined. The process-control factors for sanitizer usage include:
• Contact time
• Water hardness
• Cleanliness of surface (presence of organic matter)
Product sanitizer concentration is regulated when used on contact surfaces that touch or may touch product. For specific information related to specific compounds there are several sources of information. Among them are FSIS Directive 7120.1; 21 CFR 178.1010; 21 CFR Part 173 — and be sure to read the suppliers label.
Most sanitizers have a limited scope of organisms they affect. Rotating sanitizers can prevent a buildup of spoilage organisms. Also sanitizer effects on equipment are different. For instance, chlorine containing compounds are corrosive and do remove by oxidation in organic buildup on equipment, somewhat similar to an acid treatment. To prevent excessive corrosion, the rotation of chlorine and quaternary ammonia sanitizer keeps the surfaces bright and provides a broader spectrum of effectiveness.
In the plant environment, microorganisms have many modes of protection as they make their way from their growth niche (Listeria) or primary source (E. coli on the hide of the animal) to the finished product. These modes or layers of protection are barriers that prevent direct physical exposure of the organism to the chemical sanitizer.
Sanitizer effectiveness requires direct contact with between the sanitizer and the organisms at the molecular level. Harmful organisms are commonly embedded in a bio-film or other organic matter. The sanitizer must penetrate the protective material to be effective. For instance, a very thin layer of microscopic fat may prevent contact of a water-soluble sanitizer. This is why cleaning always precedes sanitization. Spraying 200 ppm chlorine on a dirty floor or on the hide of a carcass will only have a minimal effect on the overall microbial population.
Microbiological control would be very easy if, by simply spraying a weak chlorine solution on a contaminated surface, all of the contaminating organisms would be eliminated. Therefore when designing or evaluating a process-control system, pay particular attention to those factors that present interference to direct contact at the molecular level. The material or debris that protects often becomes the vehicle that is motorized from transfer point to transfer point in the transfer vectors.
Sanitizers do have varied ability to penetrate some level of organic matter. Obviously, this varies with sanitizer, contact time, concentration, etc. Disassembly, cleaning and sanitization to expose equipment growth niches is required to assure pathogen control.
John Weisgerber, owner of Weisgerber Consulting LLC, offers a few examples of “hurdles in the process-control system.”
A sanitizer solution can be used to treat intact packages between a chilling medium and final packaging to “manage” lot sizes when chilling media is held over for extended periods of time. For this application the treatment must be validated with challenge studies to support the efficacy of the treatment.
How different sanitizers work
By Brendan Murphy, contributing writer
There are many factors that come into play when selecting the best sanitizer to use for a given application. How a sanitizer attacks its target can affect its suitability (or otherwise!) depending on the conditions of that application. There are a number of ways sanitizers affect microorganisms, the mode of action of some commonly encountered sanitizers is summarized below.
Although several alcohols have been shown to be effective antimicrobials, ethyl alcohol and isopropyl alcohol are the most common and are widely used as skin antiseptics and hand sanitizers. Curiously, alcohols work best when diluted with water to concentrations of 60% to 90%. Little is known about the specific mode of action of alcohols, but based on their increased efficacy
Compounds like chlorine and iodine have long been used for general disinfection and as sanitizers in the food industry. The actual mechanism of halogens is not fully known but they are highly active oxidizing agents that react very quickly with all kinds of organic matter, including proteins. This non-specific attack destroys the cell’s proteins, stopping the activity of cellular enzymes and the cell dies.
Peracetic acid (PAA):
Peroxy acids are also highly active oxidizing agents that denature the cell’s proteins and enzyme systems, but they are less affected by organic material than halogens. They also increase cell wall permeability by disrupting sulfhydryl and sulfur bonds, causing the cell to leak its contents and subsequently die.
Quaternary Ammonium Compounds
QACs are positively charged surfactants that are attracted to the negative charge of the bacterial cell wall. It has been known for many years that QACs are membrane active agents with a target site predominantly at the cytoplasmic membrane in bacteria. The sequence of events in the destruction of the bacterial cell are
(i) adsorption and penetration of the QAC into the cell wall
(ii) reaction with the cytoplasmic membrane
(iii) leakage of intracellular material
(iv) cell wall lysis and death
QACs also act to dissolve the lipid coat on enveloped viruses which inactivates the virus and it can no longer replicate.
Acid anionic surfactants are negatively charged surfactants that kill bacteria in a manner very similar to QACs. In spite of having a negative charge they are able to overcome the electrostatic repulsion of the cell surface because they are formulated in a manner to provide a pH low enough to cause the cell wall’s charge to reverse and become positive. If the pH is raised then the cell’s normal negative charge is restored and the acid anionic sanitizer becomes completely ineffective.
Brendan Murphy is a senior field