Sanitizers and Disinfectants: The Chemicals of Prevention
Disinfecting Versus Sanitizing
To disinfect means to destroy or irreversibly inactivate specified infectious fungi and bacteria, but not necessarily the spores, on hard surfaces. While disinfection measures may be employed in food processing and preparation, it is much more common to utilize sanitization methods to reduce microbial presence.
To achieve the required level of sanitization or disinfection, the chemical in question must be applied at a certain concentration for a specified amount of time. These parameters are described on the product label and must be followed to achieve the desired microbial control. In most cases, these products are registered for use as pesticides with the U.S. Environmental Protection Agency (EPA). Of course, the task of ensuring the chemicals are prepared and applied properly to avoid inappropriate residues rests with the food processor and foodservice operator.
The sanitization standard for contamination reduction of food contact surfaces is generally accepted as 99.999% (a 5-log reduction) achieved in 30 seconds (Official Detergent Sanitizer Test. The process of sanitization depends upon the preparation of the surfaces in question.
Too little sanitizer, of course, can result in unacceptable efficacy, while too much sanitizer can yield residues that do not meet standards.
Hypochlorites cause broad microbial mortality by damaging the outer membrane, likely producing a loss of permeability control and eventual lysis of the cell. Spores, however, are resistant to hypochlorites, as the spore coat is not susceptible to oxidation except at high concentrations coupled with long contact times at elevated temperatures.
While hypochlorites are very reactive, their useful properties are negatively impacted by factors such as suspended solids, high temperatures, light, water impurities, and improper pH levels. In routine use, surfaces must be as free as possible of organic materials, and the pH must be maintained between 5 to 7 to ensure that the greatest amount of hypochlorous acid is available. As with any sanitizer, measurements must be taken periodically to make certain that the freely available chlorine is at the desired level.
Chlorine dioxide is an oxidizer that reacts with the proteins and fatty acids within the cell membrane, resulting in loss of permeability control and disruption of protein synthesis.
It is produced on-site as it can’t be compressed or stored commercially in gaseous form. Most chlorine dioxide generation is accomplished with complex systems. However, recent advances in formulation procedures allow the production of solutions of chlorine dioxide on-site without the use of expensive equipment.
Compared with hypochlorites, chlorine dioxide requires much lower concentrations to achieve microbial mortality.
Peroxyacetic Acid (PAA)
Mortality is produced by the disruption of chemical bonds within the cell membrane.
Quaternary Ammonium Compounds (QACs or Quats)
The positively charged cations in the compounds bind with the acidic phospholipids in the microbial cell wall.
Resistance to Sanitizers
Any time a chemical is used to produce microbial mortality, the possibility of promoting resistance exists. The sanitizer could have just missed these 10 organisms or they could inherently be immune. If these 10 microbes are indeed immune, over time they will proliferate, and the usual sanitizing concentration and/or chemical will no longer produce acceptable mortality. At this point, measures must be taken to disinfect the surfaces in question. It then becomes imperative to know what organisms are specifically present so that the proper disinfectant at the proper strength maintained for the required time can be applied.
Various forms of water can sanitize, but, as stated initially, the focus of this discussion was on the more common chemicals traditionally used for sanitization.