Abstract:
Systems and methods for antimicrobial injection in a web packaging pasteurization system are provided. A pressurized mixture of pasteurizing medium and at least one antimicrobial agent is applied to the surfaces of a food product. According to a preferred embodiment, the at least one microbial agent is injected into and thereby mixed with the pressurized supply of pasteurizing steam prior to its discharge into a pressurized chamber and application to the food surfaces. Preferably, the mixture is introduced into the pressurized chamber at an inflow rate and vented from the chamber at an outflow rate that is slower than the inflow rate such that the pressure in the chamber increases to increase the temperature of the mixture to an effective temperature for killing bacteria.

Description:
BACKGROUND 
       [0001]    The present application is directed to improved methods and systems for controlling contamination in a web packaging system. The methods and systems described herein maintain food quality and reduce the risk to the public from food-borne pathogens. 
         [0002]    Food-borne pathogens are a major concern for our society. Publicity surrounding high-profile food poisoning incidents subjects both government agencies and industries to external pressures to identify and control potential hazards caused by microbial contamination. 
         [0003]    Although generally preventable, food-borne illness remains a serious problem in the United States. Contaminated food has been estimated to cause 76 million illnesses in the United States each year, including 325,000 cases resulting in hospitalization. The Council for Agricultural Science and Technology has estimated that food-borne diseases caused by the most common bacterial pathogens found in ready-to-eat (RTE) foods—listeria monocytogens,  Campylobacter Jejuni, Escherichia coli, Salmonella  and  Staphylococcus Aureus —may cause as many as 9,000 deaths each year. The present application discloses methods and systems that will benefit public health by eliminating or reducing food-borne pathogens from RTE foods. 
         [0004]    The United States Department of Agricultural Food Safety and Inspection Service (USDA-FSIS) has established three alternative means for regulating RTE meat and poultry products that are exposed to the environment after cooking. The first alternative uses a post-lethality (post-cooking) treatment that reduces or eliminates bacterial pathogens and subsequently applies an antimicrobial agent or process that suppresses or limits bacterial pathogen growth throughout the product&#39;s shelf life. In the second alternative, the RTE product is subjected to a post-cook lethality treatment or is formulated with antimicrobial ingredients. Finally, the third alternative relies solely on good manufacturing practices and sanitation programs to control common bacterial pathogens. 
         [0005]    Researchers and processors have been working for years on developing and implementing post-cook (post-process) lethality treatments for at-risk RTE meats, such as frankfurters or wieners. The industry has options for both pre- and post-packaging lethal treatments, including steam, hot water, radiant heat, and high-pressure processing. Application of steam surface pasteurization and vacuum packaging systems allow post-process lethality treatments to be achieved at a production line speed that is comparable to that of commercial packaging for RTE foods. 
         [0006]    Web packaging machines and methods are known in the prior art. For example, the apparatus described in U.S. Pat. No. 6,843,043 packages a food product between upper and lower webs. A web transport conveyor transports the lower web through a series of stations, which form the lower web into a component of a package at a forming station, and receive the food product at a loading station, and close the package with the upper web at a closing station. A pasteurization station is located between the loading station and the closing station and pasteurizes the food product in a simple, effective manner readily and seamlessly incorporated into the packaging line. 
         [0007]    U.S. Pat. No. 7,247,330 teaches the combined treatment of vacuum-sealed food products by a thermal surface treatment and application of one or more antimicrobial agents to the surface of the food products. Thermal surface treatment is provided as a first treatment step followed immediately by the application of one or more antimicrobial agents as a second, separate treatment step. A drying step is preferably conducted between the thermal surface treatment and application of antimicrobial agents. 
         [0008]    There remains a need for more efficient, more effective, and simplified methods and systems for treating the surface of a food product to kill and/or significantly reduce the growth of food-borne pathogens without subjecting the food product to overly high temperatures for relatively long periods of time. 
       SUMMARY 
       [0009]    The present application describes improved systems and methods for controlling contamination of food product. A pressurized mixture of pasteurizing media, preferably heated steam, and at least one antimicrobial agent is applied, preferably sprayed, onto the surfaces of a food product. According to a preferred embodiment, the at least one microbial agent is injected into and thereby mixed with a pressurized supply of pasteurizing steam prior to its discharge into a pressurized chamber and application to the food surfaces. Preferably, the mixture is introduced into the pressurized chamber at an inflow rate and vented from the chamber at an outflow rate that is slower than the inflow rate such that the pressure in the chamber increases to increase the temperature of the mixture to an effective temperature for killing bacteria. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The best mode of carrying out the claimed invention is described herein with reference to the following drawing figures. 
           [0011]      FIG. 1  is an isometric view of a web packaging apparatus. 
           [0012]      FIG. 2  is a side view partially cut away of a portion of the apparatus of  FIG. 1 . 
           [0013]      FIG. 3  is an end view of the portion shown in  FIG. 2 . 
           [0014]      FIG. 4  is a top view of the portion shown in  FIG. 2 . 
           [0015]      FIG. 5  is a view of section  5 - 5  taken in  FIG. 3 . 
           [0016]      FIG. 6  is a view of section  6 - 6  taken in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]      FIG. 1  illustrates a packaging machine  10  that generally includes a lower web supply station  12  for supplying a lower web  14  of flexible packaging material from a supply roll  16 , a forming station  18 , a loading station  20 , an upper web supply station  22  for supplying an upper web of flexible packaging material  25 , and a downstream station  26  closing the package. The web transport conveyor provided by machine  10  transports lower web  14  through the noted series of stations which form the lower web  14  into a component of a package at forming station  18 , and receive a food product such as hot dogs P at loading station  20 , and close the package with the upper web  25  at closing station  26 . The upper and lower webs  14 ,  25  are advanced by an indexing apparatus (not shown) which is controlled by control modules  28 ,  30 . The conveyor advances from upstream to downstream, as shown by arrow  29 , wherein closing station  26  is downstream of loading station  20 , and loading station  20  is downstream of forming station  18 . 
         [0018]    A pasteurization station  32  is located between loading station  20  and closing station  26  and specifically downstream of loading station  20  and upstream of closing station  26 . As shown in  FIG. 2 , the pasteurization station  32  is supported by a frame  34  and includes a pressure tank  36  that facilitates a hydraulic lift mechanism  38 , the purpose of which will be explained further below. Pasteurization station  32  receives a pressurized supply of pasteurizing media  40 , which in the preferred embodiment comprises heated steam. The supply of pasteurizing steam  40  is introduced via a piping assembly  42  that comprises a series of tubes, clamps, gaskets, adapters, etc. As shown in  FIGS. 2 and 3 , jacketed header supply tube  44  deposits the supply of pasteurizing steam  40  into manifold  46 , which then distributes the pasteurizing steam  40  into three separate distribution pipes  48 . The jacketed header supply tube  44  is attached to the manifold  46  via a clamp and gasket connection  50 . In turn, the manifold  46  is connected to the distribution pipes  48  via clamp and gasket connection  52 . Each distribution pipe  48  includes opposing adapters  54  connecting a valve piston  56  to a pneumatic tee  58 . The adapters  54  and pneumatic tee  58  are connected by a clamp and gasket connection  60 . 
         [0019]    As shown in  FIG. 5 , an antimicrobial injector  62  is connected to the transverse arm  64  of the tee  58  and receives and deposits a supply of antimicrobial agent (S) into the tee  58 . The injector  62  can consist of a solenoid activated automatic spray nozzle that is specifically designed for fast on-off operation. One example of such an injector is the PulsaJet 10000 manufactured by Spraying Systems Co., however any suitable injector will suffice. The injector  62  is connected to the tee  58  by a manually removable clamp  59 , which provides a modular design that, in use, can be easily fitted and retrofitted to adapt to a variety of adapters. The clamp  59  also advantageously allows for quick and easy removal, repair and/or replacement of the injector  62 . 
         [0020]    The antimicrobial agents (S) can contain one or more antimicrobial agents that can include any effective food-grade antimicrobial compound. Suitable agents known and described in the art include antibacterial agents (also referred to as bactericidal agents) which are effective to kill or inhibit bacteria (e.g., antibiotics such as nisin, nisin-containing whey, natamycin, subtilin) or  Pediococcus -derived bacteriocins (e.g., pediocin); food-grade acids and salts of food-grade acids (e.g., acetic acid, lactic acid, malic acid, phosphoric acid, sorbic acid, benzoic acid, mixtures thereof, and the like); heat resistant antibacterial enzymes such as lysozyme; spice extracts having antibacterial properties; plant extracts having antibacterial properties (e.g., hop extracts; rosemary extracts, rosemary extract acids such as rosmarinic acid and carnosic acid); inorganic salts having antibacterial properties (e.g., acidified calcium sulfate); and other agents such as liquid smoke, parabens, or ozone; mixtures of such agents can also be used. The antimicrobial agent can be selected from food-grade acids and their salts, bacteriocins, spice extracts, plant extracts, nisin, hops acid extracts, tertiary butylhydroquinone, cetyl pyridium chloride, and mixtures thereof. 
         [0021]    The lower end  66  of the each tee  58  is connected to a respective flow passage in an upper member  70  of pasteurization deck  72 . As shown in  FIG. 6 , pasteurization deck  72  includes the upper member  70  and a lower member  74 , which are operable to sandwich and seal lower web  14  therebetween. In the illustrated embodiment, lower member  74  includes a plurality of aligned side-by-side compartments  78 ,  80 , which are pressure sealed when the upper member  70  and lower member  74  are in the closed position, shown in  FIG. 6 . Upper member  70  includes an outlet manifold  82  connected to exhaust pathways  84  and further includes the aforementioned three inlet flow passages  86 ,  88 ,  89  which, respectively, are in fluid communication with the distribution pipes  48 . Upper member  70  of pasteurization deck  72  further includes a series of sets of inlet ports, including inlet ports  92 , inlet ports  94 , inlet ports  96 , and inlet ports  98 . Inlet ports  92  are in fluid communication with inlet passage  86  and compartment  78 . Inlet ports  94  and  96  are in fluid communication with inlet passage  88  and inlet ports  94  are in fluid communication with compartment  78  and inlet ports  96  are in fluid communication with compartment  80 . Inlet ports  98  are in fluid communication with inlet passage  90  and compartment  80 . 
         [0022]    During operation, indexing apparatus indexes the conveyor from upstream to downstream in the direction shown by arrow  29 . After the lower web  14  is formed into the shape of compartments  78 ,  80  at the forming station  18 , it is indexed into position between the upper member  70  and lower member  74  of pasteurization deck  72 . In the preferred embodiment, the pasteurization deck  72  is wide enough to accept and treat numerous compartments  78 ,  80  formed in the lower web  76  in a single indexing step, as shown in  FIG. 4 . In this embodiment, a plurality of aligned compartments  78 ,  80 , respectively, are simultaneously indexed to a position that is between the upper member  70  and lower member  74  of pasteurization deck  72 . Once the plurality of compartments  78 ,  80  is indexed into position, controller  28  actuates hydraulic lift mechanism  38  to drive lower member  74  upwardly and into contact with the upper member  70 . Thus, the lower web  76  is sandwiched between the lower member  74  and upper member  70  of the pasteurization deck  72 , as shown in  FIG. 6 . 
         [0023]    Prior to, or simultaneously with the sandwiching of the upper member  70  and lower member  74 , control module  28  actuates injector  62  to inject a predetermined volume of antimicrobial agent(s) into tee  58  of piping assembly  42 . Simultaneously, or immediately subsequent to the injection of antimicrobial media into tee  58 , controller  28  causes a supply of pasteurizing steam to flow through piping assembly  42 , through manifold  46  and the respective distribution pipes  48 , and into the respective inlet passages  86 ,  88 ,  89 , as shown by arrows  86   a ,  88   a , and  89   a  respectively. Preferably the supply comprises a short burst of steam having a predetermined volume. As the pasteurizing steam passes through the tee  58 , it is mixed with the antimicrobial agent injected by the injector  62  and carries the antimicrobial agent into into the respective compartments  78 ,  80  via the inlet passages  86 ,  88 ,  89 . More specifically, the pressurized mixture flows from inlet passage  86  flows through inlet port  92  and into compartment  78 . The pressurized mixture flows from inlet passage  88 , through inlet ports  94  and  96 , and is then dispersed into respective compartments  78 ,  80  and onto the food product. The pressurized mixture flows from inlet passage  90  onto inlet ports  98  and into the respective compartments  80 . In the compartments  78 ,  80 , the mixture flows across the surfaces of the food product and exits the respective compartments via outlet ports  102 ,  104  and into the outlet manifold  82 , which leads to exhaust pathways  84 . Lastly, the controller  28  actuates the pressure tank  36  and hydraulic lift mechanism  38  to lower the lower member  74  and separate the lower member  74  from the upper member  70 . The indexing apparatus indexes the plurality of treated compartments  78 ,  80  out of position between the lower member  74  and upper member  70  and, in turn, indexes a new plurality of compartments therebetween. The treated compartments  78 ,  80  are indexed downstream for further processing, as described above. 
         [0024]    The apparatus and methods disclosed herein are especially useful for packaging wieners or similar type processed meat food products. Mixing of the pressurized supply of pasteurization medium and the injected antimicrobial agents prior to introduction into the chamber provides significant improvements over the prior art, including improved efficiency and improved bacteriostatic protection. Injection of the antimicrobial agents into the pressurized supply of pasterurization medium, and subsequent injection of the mixture into a chamber containing the food product surprisingly results in an even and thorough application of antimicrobial agent onto the surfaces of the food product. This is highly advantageous because it provides long-lasting, effective bacteriostatic protection within the sealed package, which helps increase the shelf life of the packaged food product. Rapid and effective coating of the entire surface of the food product is ensured by the high pressure supply and therefore the food products can be treated without the need for a vacuum/drying step and without much concern regarding specific flow patterns of the mixture within the chamber. This results in a much simpler apparatus for treatment of food borne pathogens and a much more timely treatment station, enhances production line speed and can be more easily incorporated into the overall packaging system. 
         [0025]    It should be understood that the drawings and specification are to be considered an exemplification of the principles of the invention, which is more particularly defined in the appended claims. The term pasteurization is used herein in accordance with its normal dictionary definition, including partial sterilization of a substance at a temperature and for a period of exposure that destroys objectionable organisms without major chemical alteration of the substance, and including destruction of pathogenic and/or spoilage organisms for extending shelf life. The pasteurizing medium is preferably steam, or alternatively hot air or superheated steam, though other types of pasteurizing media may be used. The invention may be used with various web packaging apparatus known in the art, including continuous motion type web packaging machines and indexing type web packaging machines. It is preferred that plural packages of food product be simultaneously processed at the pasteurization station, though the invention is not limited to any number, i.e., the invention includes the pasteurization of one or more product packages. Furthermore, additional pasteurization stations may be added, and the invention includes one or more pasteurization stations, each having one or more pasteurization chambers.