Drug – bio-affecting and body treating compositions – Inorganic active ingredient containing – Peroxide or compositions of or releasing gaseous oxygen or...
Reexamination Certificate
2001-06-28
2003-01-14
Pak, John (Department: 1616)
Drug, bio-affecting and body treating compositions
Inorganic active ingredient containing
Peroxide or compositions of or releasing gaseous oxygen or...
C514S557000, C514S558000, C514S559000, C514S560000, C514S568000, C514S572000, C514S574000, C514S714000, C422S028000, C422S029000, C426S333000, C426S335000, C426S532000
Reexamination Certificate
active
06506417
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of citrus fruit and, more particularly, to a disinfectant composition and process of using the composition for reducing
Xanthomonas axonopodis
organisms on citrus fruit and on equipment used with citrus.
BACKGROUND OF THE INVENTION
Xanthomonas axonopodis
pathovar (pv)
citri
is recognized as the agent of bacterial citrus canker, a highly virulent contagious disease of citrus trees which has great economic importance in all citrus growing regions of the world. Official nomenclature for this organism was changed in the 1980s from
X. campestris
pv.
citri
to
X. axonopodis
pv.
citri
so that some of the prior literature will refer to the agent of bacterial citrus canker by its old designation.
X. axonopodis
pv.
citri
is highly virulent for citrus crops, and its propagation for research purposes is, therefore, restricted to certain laboratories in the U.S. Department of Agriculture and the Florida Department of Agriculture and Consumer Services. A closely related pathovar,
X. axonopodis
pv.
citrumelo
, is the causative agent of citrus spot, a much less virulent disease than citrus canker, and is accepted as a model citrus pathogen representative of the more virulent citrus canker strain for general laboratory studies. Accordingly,
X. axonopodis
pv. citrumelo is the model organism employed for studies related to the present invention.
X. axonopodis
pv. citrumelo produces citrus spot, but tends to affect primarily nursery seedlings, rather than mature trees. A third related species sometimes found in literature reports is
X. axonopodis
pv.
vesicatoria
, causative agent of tomato spot. This pathovar is not a pathogen of citrus fruit or citrus trees.
G. Eldon Brown and T. S. Schubert proposed the use of
Xanthomonas campestris
pv.
vesicatoria
as a test model organism for use in testing the effectiveness of disinfectants against the agent of bacterial citrus canker. As part of this evaluation, they tested the effectiveness of peroxyacetic acid against the model organism, and determined that peroxyacetic acid at a concentration of 200 &mgr;g/ml produced an acceptable level of eradication comparable to approved chlorine treatments. Use of
Xanthomonas campestris
pv.
vesicatoria
to Evaluate Surface Disinfectants for Canker Quarantine Treatment of Citrus Fruit, pp. 319-323, Plant Disease, April 1987. Brown and Schubert did not test peroxyacetic acid against
Xanthomonas axonopodis
, nor did they test for effectiveness at concentrations lower than 200 &mgr;g/ml. In addition, pathovars, or strains, of Xanthomonas are very specific in their host range, that is, they are not cross-infective from one plant species to another. Thus, the citrus pathogens will not infect tomatoes, and the tomato pathogens will not infect citrus. It should be noted, however, that
X. axonopodis
pv.
citrumelo
was unknown at the time Brown and Schubert conducted their study, therefore they employed the nearest strain possible to
X. axonopodis
pv.
citri
. Nevertheless, the results published by Brown and Schubert, generated using a tomato pathogen, may not be predictably extrapolated to a citrus pathogen.
The control of infection and spread of these microbial plants pathogens has been a troublesome problem for many years in the citrus industry. Certain citrus growing areas, through governmental regulatory agencies, require control of these organisms on citrus fruit surfaces and on citrus fruit processing equipment. Treatments presently approved for control of these microorganisms on citrus fruit and on processing equipment include quaternary ammonium compounds, which have a tendency to injure the fruit, producing blemishes and potentially rendering the citrus fruit unfit for human consumption.
In addition, quaternary ammonium compositions exhibit residual activity which remains on the fruit processing equipment after drying following application of the sanitizer. Such residual activity may also injure the fruit during processing, producing blemishes and possibly making the fruit unmarketable.
SUMMARY OF THE INVENTION
With the foregoing in mind, the present invention advantageously provides a disinfectant composition for substantially reducing bacterial citrus canker organisms on citrus fruit and citrus fruit processing equipment.
The composition comprises from approximately greater than 10 to less than 100 parts per million of peroxyacetic acid in an equilibrium aqueous solution with hydrogen peroxide, and acetic acid.
Additionally, the composition is used in a process substantially reducing bacterial citrus pathogen organisms on citrus fruit and citrus fruit processing equipment by contacting with a sufficient concentration of peroxyacetic acid and for a sufficient time for reducing the citrus pathogen organisms by at least 99.9%.
The composition and process of the present invention provide broad spectrum activity against bacterial citrus pathogens and other microbial contaminants. The composition is effective at temperatures from about 5° C. to about 40° C. (41° to 104° F.), and at a pH up to about 8.0. Further, the composition once applied will degrade into harmless compounds including acetic acid, oxygen, water and carbon dioxide. The generally acidic pH of the composition tends to help remove mineral deposits from fruit processing equipment. The composition also exhibits low corrosiveness and will not harm stainless steel citrus fruit processing equipment. Because the composition chemically degrades after application, the process requires no rinsing after disinfection, thus saving time and water.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described more fully hereinafter. This invention may, however, be embodied in many different forms and should not be construed as limited to the described embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The invention discloses a disinfectant composition effective against a pathovar of
Xanthomonas axonopodis
pathogenic for citrus. The composition comprises an aqueous solution of a carboxylic acid, hydrogen peroxide, and a percarboxylic acid product thereof. An embodiment of the composition comprises a percaboxylic acid in combination with hydrogen peroxide, and preferably in an equilibrium aqueous solution with hydrogen peroxide, and acetic acid. Such an embodiment of the composition of the invention may be expressed in the following exemplary formulas.
CH
3
COOH
+
H
2
O
⇆
CH
3
OOOH
+
H
2
O
Acetic
Acid
Hydrogen
Peracetic
Acid
Water
(
HOAc
)
Peroxide
(
PAA
)
K
eq
=
[
PAA
]
[
H
2
O
]
[
HOAc
]
[
H
2
O
2
]
PKa
PAA
=
8.2
PKa
HOAc
=
4.7
The disinfectant composition optionally may include up to approximately 1% by weight of sulfuric acid, to provide enhanced antimicrobial action. Additionally, the composition comprises at least approximately 10 parts per million of the percarboxylic acid, and more preferably at least approximately 30 parts per million of the percarboxylic acid. For use, an effective concentration of the composition includes less than approximately 85 parts per million of the percarboxylic acid.
The disinfectant composition should include sufficient percarboxylic acid to reduce the pathovar by at least 99.9%, and preferably to accomplish the reduction within less than approximately five minutes of contact time.
Another preferred embodiment of the disinfectant composition comprises less than 200 parts per million of peroxyacetic acid in an equilibrium aqueous solution with hydrogen peroxide, and acetic acid. As described above, this embodiment of the disinfectant composition may optionally include up to approximately 1% by weight of sulfuric acid. This composition also compris
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
FMC Technologies Inc.
Pak John
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