Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2001-11-15
2002-10-29
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S253000, C510S258000, C510S247000, C424S718000
Reexamination Certificate
active
06472358
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to acid sanitizing and/or cleaning compositions comprising antimicrobially effective C
5
to C
4
carboxylic acids. The present invention is directed to both concentrates and to water diluted use solutions.
BACKGROUND OF THE INVENTION
Periodic cleaning and sanitizing in food, drink, pharmaceutical, cosmetic and similar processing industries; in food preparation and service businesses; in health and day care facilities; and, in hospitality establishments are a necessary practice for product quality and public health. Residuals left on equipment surfaces or contaminants found in the process or service environment can harbor and nourish growth of subsequent processed product or critical contact surfaces. Protecting the consumer against potential health hazards associated with pathogens or toxins and maintaining the quality of the product or service requires routine cleaning of residuals from surfaces and effective sanitation to reduce microbial populations.
Visual inspection of the equipment cannot ensure that surfaces are clean or free of microorganisms. Antimicrobial treatments as well as cleaning treatments are therefore required for all critical surfaces in order to reduce microbial population to safe levels established by public health regulations. This process is generally referred to as sanitizing. The practice is of sanitation is particularly of concern in food process facilities wherein the cleaning treatment is followed by an antimicrobial treatment applied upon all critical surfaces and environmental surfaces to reduce the microbial population to safe levels established by ordinance. A sanitized surface is, as defined by the Environmental Protection Agency (EPA), a consequence of a process or program containing both an initial cleaning and a subsequent sanitizing treatment which must be separated by a potable water rinse. A sanitizing treatment applied to a cleaned food contact surface must result in a reduction in population of at least 99.999% (5 log) for specified microorganisms as defined by the “Germicidal and Detergent Sanitizing Action of Disinfectants”,
Official Methods of Analysis of the Association of Official Analytical Chemists,
paragraph 960.09 and applicable sections, 15
th
Edition, 1990 (EPA Guideline 91-1).
The antimicrobial efficacy of sanitizing treatments is significantly reduced if the surface is not absolutely free of soil and other contaminants prior to the sanitizing step. The presence of residual food soil and/or mineral deposits inhibit sanitizing treatments by acting as physical barriers which shield microorganisms lying within the organic or inorganic layer from the microbicide. Furthermore, chemical interactions between the microbicide and certain contaminants can disrupt the killing mechanism of the microbicide.
With the advent of automated clean-in-place and sanitize-in-place systems, the need for disassembly has been diminished, and cleaning and sanitizing have become much more effective. However, modern food industries still rely on sanitizers to compensate for design deficiencies or operational limitations in their cleaning programs and the probability of very small residual amounts of organic and inorganic soils and biofilms remaining on food contact surfaces after cleaning. In cooperation with these process changes and higher performance expectations, sanitizer treatments must also comply with the increasing demand for safer, less corrosive, more environmentally friendly compositions.
According to the U.S. Center for Disease Control and Prevention, food poisoning in calendar year 2000 resulted in 5000 deaths, 325,000 hospitalizations and 76,000,000 illnesses. The need exists for improved sanitizing treatments to destroy pathogens and food spoilage microorganisms resistant to conventional treatments within the food gathering, food processing, and food serving industries. A further complication is that the list of approved microbicidal agents has continued to decrease due to acute and chronic human toxicity of some microbicidal agents, and to their environmental persistence in water supplies.
Antimicrobially active acids have been used in sanitizing operations. For instance, U.S. Pat. No 404,040 describes a sanitizing composition comprising aliphatic, short chain fatty acids, a hydrotrope or solubilizer for the fatty acids, and a hydrotrope-compatible acid, and U.S. Pat. No. 5,330,769 describes fatty acid sanitizer concentrates and diluted final solutions which include individual amounts of germicidally effective fatty acid, hydrotrope, a strong acid group consisting of phosphoric acid and sulfuric acid or mixtures thereof sufficient to lower the pH of the final solutions to about 1-5, and a concentrate stabilizing weak acid component selected from the group consisting of propionic, butyric and valeric acids and mixtures thereof.
Protonated carboxylic acids offer broad spectrum antimicrobial activity against gram-positive and gram negative bacteria, persistent biocidal activity in the presence of organic and inorganic soils and residual biocidal and inhibitory activity. They combine both acid for mineral deposit control and sanitizer for antimicrobial effect into one treatment solution.
However, one problem associated with the use of protonated carboxylic acid sanitizers is poor use dilution phase stability, particularly at lower water temperatures of 40°-50° F. 50° F. Fatty monocarboxylic acids having alkyl chains containing 5 or more carbon atoms, are typically characterized as water insoluble and can oil out or precipitate from solution as a gelatinous flocculent. Solubility tends to decrease with decreasing water temperature and increasing ionic concentration. Furthermore, the oil or precipitate can affix to the very surfaces which the sanitizing solution is intended to sanitize, such as equipment surfaces, leading to a film formation on these surfaces over time. The fatty acid film deposited and left remaining on the equipment surface tends to have a higher pH than the sanitizing solution from which it came resulting in a significantly lowered biocidal efficacy, and, if mixed with food soil, may result in a film matrix which has the potential of harboring bacteria, an effect opposite to that desired.
One solution has been to use short chain, C
1
-C
4
carboxylic or hydroxycarboxylic acids to solubilize and thus stabilize longer chain fatty acids in high actives composition concentrates. However, these short chain weak acids have been known to be less effective at normal use dilution concentrations than their longer chain counterparts, and extreme dilution of the concentrate in water leads to a decrease in the solvating effect resulting in a precipitate of the longer chain length fatty acids of C
5
or higher from solution. Furthermore, raising the concentration of the C
1
-C
4
acids increases the cost of the sanitizing composition, and does not appear to result in a significant increase in dilution stability or to improved antimicrobial efficacy.
Organic hydrotropes or coupling agents, such as low molecular weight sulfonates, may be employed to increase the solubility and miscibility of the longer chain fatty acids with water and inorganic salts both in concentrated and in diluted use solutions. Again, the solubility appears to diminish at sustained lower water temperatures with the result being phase separation.
There remains a need in the art for an improved biocidal composition which utilizes a carboxylic fatty acid which has high antimicrobial efficacy, has good phase stability, exhibits low toxicity, and is not detrimental to the environment.
SUMMARY OF THE INVENTION
Surprisingly, the compositions of the present invention exhibit excellent phase stability both in concentrated form and in diluted use solutions, and in particular, they exhibit excellent phase stability in low temperature water diluted use solutions. Even more surprisingly, the stability is improved in the presence of nitric acid.
The sanitizing and/or cleaning compositions of the present invention, in bot
Podtburg Teresa C.
Reinhardt Duane Joseph
Richter Francis Lawrence
Staub Richard R.
Boyer Charles
EcoLab Inc.
Vidas Arrett & Steinkraus P.A.
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