Patent Application
20070059414
1. Field of the Invention
The invention relates to the improvement of sanitization techniques used during the processing of food products, more specifically to a method of treating food products using an antimicrobial gas mixture and a treating agent comprising a microorganism-signal-inhibiting agent.
2. Description of the Related Art
As microorganisms grow and increase in population density, small signaling molecules are produced to turn on genes in surrounding microorganisms for the production of biofilms, toxins, and other characteristics of the community. Autoinducing chemical signals were first described in the marine symbiont, Vibrio fischeri in the 1970's associated with bioluminescence. Since then, low molecular weight chemical signaling in bacteria as a result of high population density has been termed “quorum sensing”. Quorum sensing is a phenomenon whereby bacteria use small signaling molecules for cell-to-cell communication in response to cell population densities and environmental stresses such as food processing and storage. Virulence characteristics of pathogenic microorganisms such as antibiotic production, biofilm formation, sporulation, and toxin production may be controlled by such signaling molecules and mechanisms.
Different autoinducing compounds for intraspecies signaling have been described for Gram-negative and Gram-positive bacteria. One furanone derivative, designated autoinducer-2 (Al-2), serves a signaling role among and between different Gram-negative and Gram-positive bacteria. Al-2 synthesis is dependent upon the synthetase, LuxS, expressed by the luxS gene. The acceptance of Al-2 as a universal quorum-sensing molecule results from the conserved predominance of luxS homologues in many bacteria even though the presence of Al-2 has not been confirmed in all instances.
Numerous studies to date have reported natural inhibitors of Al-2-directed cellular signaling processes. Many of these quorum sensing analogues or inhibitors, are also aromatic compounds important in the flavor or aroma of fruits and vegetables. 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF), a fungal inhibitor produced naturally by strawberries, is an important component of the attractive aroma of certain fruit and a volatile inhibitor of quorum sensing. A furanone produced by the sea alga, Delisea pulchra, inhibited virulence characteristics, such as biofilm formation and swarming of E. coli. Another naturally occurring furanone, ascorbic acid (vitamin C), has antimicrobial properties similar to other known natural inhibitors of quorum sensing.
Over 30% of the 5,000 food-borne deaths in the United States each year are caused by three pathogens: Salmonella, Listeria, and Toxoplasma. Approximately 2 to 4 million cases of Salmonellosis occur annually in the U.S. While only 2,000 cases of Listeriosis are reported, over 20% of these result in death. Similarly, over 60,000 cases of E. coli O157:H7 food-borne disease are estimated annually, with 3% of these resulting in hospitalizations, and 0.1% in deaths. Many of these diseases are preventable and the incidence of these and similar food-borne pathogens could be reduced by altering conditions necessary to trigger gene expression related to food-borne illness.
Modified atmosphere packaging (MAP) has proven to be ineffective in eliminating potential pathogens in packaged food products. The most common gases used to modify a food product's atmospheric environment with the intention of inhibiting microbial growth while increasing product shelf-life include oxygen (O2), carbon dioxide (CO2), and nitrogen (N2). Reducing O2 concentrations from 21% to 1-5% reduce respiration rates of fruits and vegetables, thereby slowing ripening and maturation. Levels of O2 below 1% however, are detrimental to produce flavors and increase hazards from anaerobic pathogens. Oxygen levels above 70% have been shown to be effective in inhibiting the growth of certain microorganisms, but also stimulate the growth of the food-borne pathogens, E. coli and L. monocytogenes. Carbon dioxide is also known to affect microbial growth. While CO2 has been reported to have inhibitory effects on microorganisms at elevated concentrations above 5%, spoilage lactic acid bacteria can then thrive and reduce the shelf-life of the food products. 10-20% CO2 has been shown to inhibit Salmonella enteriditis, but not Salmonella typhimurium. Another pathogen of concern in ready-to-eat deli meat products, L. monocytogenes, is capable of withstanding levels of CO2 up to 50%. Unrestricted over-use of CO2 can create undesirable color changes in meats. Also, if CO2 is added in very high concentrations, product flavors may be compromised and samples may become anaerobic permitting the growth of Clostridium botulinum, responsible for a very potent neurotoxin.
If quorum sensing mechanisms can be inhibited in food-borne microorganisms, the microorganisms may be less resistant to antimicrobial treatments and less likely to cause illness or disease. Therefore, a method is needed to inhibit growth and quorum sensing mechanisms in food-borne microorganisms that might otherwise express virulent characteristics.
Aspects of the invention generally provide methods and treating agents for inhibiting growth and quorum sensing mechanisms in food-borne microorganisms. In one embodiment, the invention provides a method for treating a food product comprising exposing the food product to a microorganism-signal-inhibiting agent and a gas mixture simultaneously.
In another embodiment, the invention provides a method of packaging a food product comprising placing a food product in a container possessing a treating agent, wherein the treating agent comprises a microorganism-signal-inhibiting agent, flushing the container with a gas mixture after placing the food product in the container, and sealing the container after flushing the container with the gas mixture.
In another embodiment, the invention provides A method of packaging a food product comprising placing a food product in a container possessing a treating agent, wherein the treating agent comprises microorganism-signal-inhibiting agent, creating a vacuum in the container after placing the food product in the container, flushing the container with a gas mixture after placing the food product in the container, and sealing the container after flushing the container with the gas mixture.
For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:
The words and phrases used herein should be given their ordinary and customary meaning in the art by one skilled in the art unless otherwise further defined.
In the following, reference is made to embodiments of the invention. However, it should be understood that the invention is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the invention. Furthermore, in various embodiments the invention provides numerous advantages over the prior art. However, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).
Quorum sensing is a phenomenon whereby microorganisms use small signaling molecules for cell-to-cell communication in response to cell population densities and environmental stresses. As microorganisms grow and increase in population density, small signaling molecules are produced to turn on genes in surrounding microorganisms for the production of biofilms, toxins, and other characteristics of the community. If these signaling mechanisms can be turned off or inhibited during food processing steps, the microorganisms will be less resistant to antimicrobial treatments and less likely to cause illness or disease. Aspects of the invention generally provide methods and treating agents for inhibiting growth and quorum sensing mechanisms in food-borne microorganisms. More specifically, embodiments of the invention provide a means of treating food products by simultaneously exposing the food product to an antimicrobial gas mixture and a microorganism-signal-inhibiting treating agent. In various embodiments, the treating agent may be a furanone, a furanone analogue and/or a furanone derivative. However, while embodiments described below are described with reference to furanones, it is contemplated that any signal inhibiting treating agent may be used instead or in addition. Thus, the microorganism-signal-inhibiting treating agent refers to any molecule, natural or synthetic, known to inhibit signaling mechanisms in microorganisms.
The processing steps 102-108 according to the embodiments of the invention are described below. The embodiments described herein are provided to illustrate the invention and the particular embodiments shown should not be used to limit the scope of the invention.
Preferred processes and apparatus for practicing the present invention have been described. It will be understood and readily apparent to the skilled artisan that many changes and modifications may be made to the above-described embodiments without departing from the spirit and the scope of the present invention. The foregoing is illustrative only and that other embodiments of the integrated processes and apparatus may be employed without departing from the true scope of the invention defined in the following claims.
This application claims the benefit under 35 U.S.C. §119(e) to provisional application No. 60/716,467, filed Sep. 13, 2005, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60716467 | Sep 2005 | US |
