Dynamic Ox biological burden reduction

Details Dynamic Ox biological burden reduction Dynamic Ox biological burden reduction

1998-12-22

2001-09-04

Warden, Sr., Robert J. (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Process disinfecting, preserving, deodorizing, or sterilizing

Using disinfecting or sterilizing substance

C422S022000, C422S023000, C422S028000, C422S030000, C422S033000, C422S186070, C422S292000, C210S748080

Reexamination Certificate

active

06284193

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to a method and apparatus that can be utilized to significantly reduce the biological load on consumer products such as food products, botanicals, cosmetic ingredients and medical products, which have traditionally been treated with commercial sterilants or fumigants such as ethylene oxide, propylene oxide, methyl bromide, hydrogen phosphide, steam (heat), irradiation, and the like.
BACKGROUND OF THE INVENTION
Currently, ethylene oxide (EO) is the agent of choice for virtually all of the gaseous sterilization of consumer products performed in the United States. EO, however, has a number of properties which limit its use as a sterilant. For example, EO is highly flammable and highly explosive. For this reason, all EO sterilization facilities must include damage-limiting construction and all equipment used in the EO sterilization process must be explosion proof In addition, high concentrations of EO are acutely toxic for humans, and EO has been implicated as a carcinogen in laboratory animals. EO sterilization plants must, therefore, be outfitted with expensive equipment to minimize exposure of facility personnel to EO and to prevent escape of EO to the atmosphere outside the facility.
Another disadvantage of EO is that it reacts with chlorine to form ethylene chlorhydrin (ECH) and with water to form ethylene glycol (EG). Both of these byproducts are toxic and must be reduced to safe levels before sterilized materials are released for use. In fact, formation of ECH and EG preclude the use of EO for sterilization of a number of food products for which it would otherwise be a very useful sterilant.
Over the last fifty years, a number of other gases that lack one or more of the disadvantages of EO have been tested as sterilants. These gases include, for example, hydrogen peroxide, ozone and chlorine dioxide. However, no other gas has proven to be as efficacious as EO for use in large volume industrial sterilizers. The most common reason for failure of these gases as useful sterilants has been inadequate permeation of the gases through packaging materials and into lumens and interstices of the product being sterilized. Failure to permeate may be due to a number of factors including size of the sterilant molecule, reactivity of the sterilant molecule with outer packaging materials prior to reaching the target material, and degradation of the sterilant molecule prior to reaching the target material.
A number of commercial fumigants are presently used to treat foodstuffs and other stored commodities. The most widely used fumigants are methyl bromide, hydrogen phosphide, carbon dioxide, and hydrogen cyanide. Many of these compounds pose hazardous conditions for application personnel and can form deleterious residues in the foodstuffs and commodities that are treated. Methyl bromide, the most widely used fumigant, has been identified as an ozone layer depleting agent and is slated, under the Montreal Protocols of 1997, to be banned by the year 2005. One important factor that differentiates the above listed fumigants from other sterilants is their ability to readily permeate granular or powdered products, which allows the fumgant to contact the infesting pests in such products.
Some of the above-mentioned traditional sterilants or fumigants have been identified with the formation of carcinogens and mutagens which thus limit the products that can be treated.
Other procedures that have been developed to treat products utilize heat, ionizing radiation, and other chemical compounds. All of these procedures are potentially detrimental to the products' nutritional, physical and/or chemical attributes and thus make them undesirable.
Thus, a means to reduce biological loads in consumer products to eliminate human pathogens while maintaining product stability remains a necessity. Accordingly, there remains a need for better alternative methods and apparatus for reducing the biological load on consumer products.
SUMMARY OF THE INVENTION
It is desirable to treat a wide variety of consumer products in chamber type operations in a cost effective manner. The method and apparatus of the present invention permit sterilization or fumigation (hereinafter referred to as “biological burden reduction” of a product in its original container (e.g., burlap bag, fiber drum, kraft paper bag, plastic bag, etc.). Thus, double handling, product loss, and post treatment contamination are reduced.
The method of the present invention utilizes a gaseous mixture containing O
1
, O
2
and O
3
(hereinafter referred to as “O
x
”) in a technologically advanced treatment system that overcomes the limitations formerly encountered with O
3
treatment on biological burden. Prior O
3
treatments include, for example, (1) the submersion of an article to be sterilized in ozone-containing water and the bubbling of ozonated water over the article (see, e.g., U.S. Pat. No. 4,517,159 to Karlson and U.S. Pat. No. 4,640,872 to Burleson); and (2) the static treatment of medical devices and food products with gaseous ozone (see, e.g., U.S. Pat. No. 3,179,017 to Shapiro et al., U.S. Pat. No. 5,069,880 to Karlson, and U.S. Pat. No. 5,120,512 to Masuda.) Systems utilizing ozone as a sterilant such as described above have encountered several limitations. The incorporation of ozone gas into water and then submersion of items(s) to be sterilized or the spraying of ozone treated water onto the surface of item(s) to be sterilized limit the process to products that can be soaked in water. The few gaseous uses of ozone have been limited to the surface treatment of medical devices and the like due to the lack of adequate penetration into compacted products. Thus, although these past processes have proven the efficacy of ozone as a sterilant, the limitation of the use of ozone as a surface treatment has not presented ozone as a reliable sterilant or fumigant for products contained with commercial containers. Furthermore, until recently, high concentration ozone generators, which would have allowed the present invention to properly function, have not been commercially available. The present invention requires a relatively high concentration of O
x
for an extended treatment period to assist the required permeation of the O
x
into the substrate bring treated. In addition to the generation of the ozone molecule, the present invention also utilizes the quenching effect of other inert gases to assist ozone generation, thereby increasing the stability of the O
x
radicals. A combination of oxygen, carbon dioxide, argon, and nitrogen have been used in the method of the present invention to achieve these factors. In addition to the benefits discussed above, the use of small quantities of carbon dioxide results in an increase in the rate of respiration in insects and some microbes, thus further aiding the action of the O
x
gases. Furthermore, the presence of atmospheric nitrogen has been utilized in the food industry for many years to protect sensitive oils and fats from oxidative rancidity. Small quantities of nitrogen can be used in the method of the present invention to assist in the protection of sensitive food components as well as assisting in the stabilization of the O
x
generation.
As an aid to understanding the invention, but without being limited thereby, the present invention is based on the discovery of the following:
1. That water submersion in O
3
sterilization is unnecessary and, in many cases, undesirable;
2. That use of gaseous O
3
in a static fashion, in many cases, does not provide adequate penetration of O
3
into products being treated;
3. That treating a product in-situ (no repackaging needed) is desirable;
4. That the use of cooler temperatures, in many cases, is desirable; and
5. That the destruction of insects and their eggs is desirable.
Accordingly, it is an object of the present invention to provide a method and apparatus for reducing biological burden from consumer products.
It is another object of the present invention to provide a method and apparatus for r

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