Abstract:
A packaging system for a fresh meat product is disclosed. The packaging system includes a tray having a base and a wall defining an interior space. The tray has an outward protruding lip extending generally around a perimeter of an upper portion of the wall. An oxygen permeable film surrounds the tray and covers the interior space. The film further defines a second space external to the tray between the outward protruding lip and the base. The protruding lip has at least one channel, the channel connecting the interior space to the second space. The oxygen permeable film includes openings sized to allow exchange of gases between the second space and the surrounding atmosphere.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a fresh meat packaging system. More particularly, it relates to a retail, case-ready package and a method of packaging fresh meat in a controlled atmosphere, to extend the shelf life of packaged meat products.  
           [0002]    Fresh meat products are typically processed from primals to various cuts in a meat processing facility, and then packaged in controlled atmospheric conditions for shipment directly to a retailer, such as a grocery store or supermarket. One typical meat packaging technique includes placing the cuts on styrofoam trays, which are then overwrapped with a permeable clear plastic film. These overwrapped trays are then placed within a vacuum-packed and gas-flushed barrier bag.  
           [0003]    In the case of red meat, controlled exposure of the meat product to oxygen is necessary to oxygenate the meat pigment to bright red oxymyglobin. This controlled oxygen exposure results in a desired “bloom” of the meat to a bright red color, which the typical retail customer associates with freshness. However, in the case of red meat, prolonged exposure to oxygen causes the conversation of myoglobin meat pigmentation to metmyoglobin having a gray or brown color that is generally considered undesirable to the typical retail customer. Furthermore, prolonged exposure of fresh meat to oxygen also often causes bacterial decay of the meat product.  
           [0004]    To prevent discoloration and extend the shelf life of meat products, modified atmosphere packaging techniques are used. For example, U.S. Pat. Nos. 5,667,827 and 5,711,978 to Breen et al. disclose a package and process for packaging fresh meat in a substantially oxygen-free atmosphere. The Breen patents disclose use of a tray that is ventilated with holes and overwrapped with a plastic wrapping material that includes slits to allow exchange of gases with the external atmosphere. These patents disclose placing a number of these trays within a barrier bag that is evacuated and flushed with carbon dioxide and then sealed. The outer barrier bag prevents oxygen from reaching the meat products and causing bacterial decay or discoloration. When the retailer is ready to display the meat product in a display case, the outer bag is removed, which allows oxygen from the atmosphere to reach the meat product and cause the meat product to bloom.  
           [0005]    One problem associated with this system is that the gas barrier meat tray includes openings through a side or end wall, which allows purge from the meat product to leak from the tray and which are susceptible to blockage by movement of the meat product within the tray. The purge can also then leak through the perforations in the film onto the meat display case. These problems are exacerbated in a typical meat display case, where packages containing meat cuts are often placed in the case at an angle to enhance the consumer&#39;s ability to adequately view the product.  
           [0006]    There is a need in the art for a fresh meat packaging system that would extend the storage life of meat products and allow the meat products to properly bloom by allowing oxygen from the atmosphere to reach the meat product located in the tray, while preventing purge from leaking from the tray.  
         BRIEF SUMMARY OF THE INVENTION  
         [0007]    The present invention, in one embodiment, is a fresh meat packaging system. The packaging system includes a tray having a base and a wall defining an interior space. The tray has an outward protruding lip extending generally around a perimeter of an upper portion of the wall. A film surrounds the tray and covers the interior space. The film further defines a second space external to the tray between the outward protruding lip and the base. The protruding lip has at least one channel located in the wall, the channel connecting the interior space to the second space. The film includes openings sized to allow exchange of gases between the second space and the surrounding atmosphere.  
           [0008]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a perspective view of a film-covered fresh meat packaging system according to one embodiment of the present invention.  
         [0010]    [0010]FIG. 2 is a bottom plan view of the packaging tray of FIG. 1.  
         [0011]    [0011]FIG. 3 is an end plan view of the film-covered meat packaging system of FIG. 1.  
         [0012]    [0012]FIG. 4 is a perspective view of a packaging tray according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]    [0013]FIG. 1 shows a top perspective view of a fresh meat packaging system  10 . As shown in FIG. 1, the packaging system  10  includes a tray  12  and a film  14 . For purposes of illustration, the film  14  is shown in a cut-away view. In a complete packaging system  10 , the film  14  covers the entire tray  12 . In one embodiment of the present invention, the tray  12  is constructed from a material that is impermeable to oxygen. In various embodiments, the tray  12  is constructed from a thermoplastic, such as polyvinyl, polypropylene, and polystyrene. In one embodiment, the tray  12  is fabricated using an injection molding process. The film  14  is a plastic wrapping material or film. In one embodiment, the film  14  is oxygen permeable.  
         [0014]    As shown in FIG. 1, the tray  12  includes a base  15  and a pair of generally opposing sidewalls  16  and generally opposing endwalls  18 . Near a top surface of the tray  12 , the sidewalls  16  and endwalls  18  meet to form a lip  20  extending around the perimeter of the upper surface of the tray  12 . In other embodiments of the present invention, the tray includes a single wall extending around the periphery of the base  15 . As shown in FIG. 1, the lip  20  is generally U-shaped with an open side facing downward. The lip  20  includes one or more channels  22  located on one or both of the endwalls  18  of the tray  12 . As shown in FIG. 1, in one embodiment, the tray  12  includes four such channels  22 . As shown, the channels  22  are located away from the sidewalls  16 . The channels  22  in the lip  20  extend both downward from an upper surface  24  and inward from an outer lip surface  26 . This configuration of the channel  22  in combination with the film  14  defines a passage extending from the inside to the outside of the tray  12 .  
         [0015]    [0015]FIG. 2 is a bottom plan view of the tray  12 . FIG. 2 shows the lip  20  extending generally around the periphery of the tray  12 . As shown, the channels  22  include an inward channeled-groove  28  into the outer wall  26  of the lip  20 . The walls  16  and  18 , together with the upper surface  24  and the outer surface  26  of the lip  20 , define a plenum  30  extending around the entire periphery of the tray  12 . As shown, in this embodiment, the plenum  30  is open to the outside of the tray  12 . In another embodiment, the lip  20  further includes a lower surface, which acts to enclose the plenum  30 .  
         [0016]    [0016]FIG. 3 is a plan view of an end of the meat packaging system  10 . As shown in FIG. 3, the tray  12  and the film  14  define two enclosed spaces. An inner enclosed space  34  (also shown in FIG. 1) is defined by the hollow interior surface of the tray  12  and the film  14  extending across the top of the tray  12  supported by the lip  20 . An outer enclosed space  36  is defined by an exterior surface of the tray  12  and the portion of the film  14  extending from the outer surface  26  of the lip  20  to a bottom surface of the tray  12 . As shown in FIG. 3, the outer enclosed space  36  extends around the entire external periphery of the tray  12 . The inner enclosed space  34  and the outer enclosed space  36  are connected to one another through the channels  22 . As further shown in FIG. 3, in one embodiment, the film  14  includes one or more openings  38  which enable gas communication between the outer enclosed space  36  and the atmosphere. In one embodiment, the one or more openings  38  are located only in the portions of the film  14  associated with the ends of the tray  12 . In one embodiment, the openings  38  are located in the film  14  only along one side of the tray  12 . In one embodiment, the openings  38  are located in the film  14  along a top side of the tray  12 . In various embodiments, the openings  38  are holes, slits, or perforations in the film  14 .  
         [0017]    [0017]FIG. 4 shows a tray  40  according to another embodiment of the present invention. As shown in FIG. 4, the tray  40  includes a base  42  a wall  44  and a lip  46 . The lip  46  includes one or more channels  48  located on one or both ends of the tray  40 . As shown in FIG. 4, in one embodiment, the tray  40  includes four such channels  48 . The channels  48  in the lip  46  extend both downward from an upper surface of the lip and inward from an outer surface of the lip. As further shown in FIG. 4, the wall  44  is generally hourglass-shaped, such that the wall  44  forms a waist  50  near a longitudinal midpoint of the tray  40 .  
         [0018]    During use of the fresh meat packaging system  10 , pre-fabricated cuts of meat product are placed into the tray  12 . In one embodiment, a soaker pad is placed beneath the meat product. Next, both the tray  12  and the meat product are wrapped with film  14 . In one embodiment of the present invention, the film  14  is heat sealed. In one embodiment, the tray  12  is not wrapped, but rather is enclosed in the film  14 . Next, the openings  38  are made in the film  14  in an area outside of the tray  12 . In one embodiment, the openings  38  are placed in the film  14  prior to placement around the tray  12 . In one embodiment, the openings  38  are placed just below the outer surface  26  of the lip  20 . In one embodiment, the openings are placed just below the outer surface  26  of the portion of the lip  20  supported by the endwalls  18 . In one embodiment, the openings  38  extend through both the film  14  and the outer surface  26  of the lip  20 . In one embodiment, the openings  38  are placed about half-way between the lip  20  and the bottom surface of the tray  12 . In one embodiment, the openings  38  are placed along a top endwall  18 , such that when the tray  12  is placed upright in the display case, any purge from the meat product will not leak through the openings  38 .  
         [0019]    In one embodiment, approximately fifteen to approximately thirty-five opening  38  are placed generally in a line extending between the endwalls  18 . In one embodiment, approximately thirty to thirty-five openings  38  are placed generally in a line extending between the endwalls  18 . In one embodiment, the opening  38  are placed in any other configuration and location limited only by the requirement that the openings  38  extend into the outer enclosed space  36 . In one embodiment, the openings  38  have an initial, pre-heat-shrink diameter ranging in size from about fifteen to about fifty mils. In one embodiment, the initial, pre-heat-shrink diameter of the openings  38  is between thirty and forty mils. In one embodiment, the size of the openings  38  is directly proportional to the volume of the inner enclosed space  34 , such that a larger volume tray has a larger opening  38  diameter.  
         [0020]    In one embodiment, the film  14  is then subjected to a heat-shrink process to place a tension on the film  14  surrounding the tray  12 . This tension, helps prevent the film  14  from collapsing onto the meat product located inside the enclosed space  34 . By creating tension in the film  14 , the heat-shrink process also results in an increase in the diameter of the openings  38 . In one embodiment, the diameter of the openings  38 , after completion of the heat-shrink process is approximately fifty to approximately ninety mils. In one embodiment, the diameter of the openings  38 , after completion of the heat-shrink process is approximately sixty to approximately eighty mils.  
         [0021]    The packaging system  10  is then placed inside a barrier bag (not shown) which is evacuated of atmospheric gases and flushed with a preservation enhancing gas, such as nitrogen or carbon dioxide. During this evacuation process, gases in the inner enclosed space  34  flow through the channels  22  into the outer enclosed space  36  and then through the openings  38  into the barrier bag. The channels  22  and openings  38  prevent the film  14  from collapsing on the meat product during the evacuation process. Likewise, any preservation enhancing gases introduced into the barrier bag enter the inner enclosed space  34  of the tray  12  using the same flow path. Any gases introduced into the barrier bag also enter the inner enclosed space  34  through the permeable film  14 . In one embodiment, where the openings  38  are located only in a portion of the film  14  associated with one side of the tray  12 , the evacuation process results in a residual oxygen level in the inner enclosed space  34  of less than about 250 ppm.  
         [0022]    Next, the barrier bags containing individual covered trays are shipped to the retailer. When the retailer receives the package, he removes the meat packaging system  10  from the outer barrier bag. This allows atmospheric gases, including oxygen to flow into the outer enclosed space  36  through the openings  38 . These gases then flow from the outer enclosed space  36  into the enclosed inner space  34  through the one or more channels  22 . Simultaneously, the atmospheric gasses enter the inner enclosed space  34  through the permeable film  14 . This process gradually increases the oxygen content within the first enclosed space  34 , which allows the cut of meat therein to bloom.  
         [0023]    Because of the design of the meat packaging system  10 , the retailer can place the packaging system  10  in the retail case in a vertical or generally vertical fashion. The absence of any perforations or holes on the walls  16 ,  18  of the tray  12  ensures that any purge from the meat product remain contained within the enclosed inner space  34 . The placement of the channel  22  on the lip  20  prevents the channel  22  from becoming blocked by purge from the meat product, and thus allows the inner enclosed space  34  to continue to exchange gases with the atmosphere. Placement of the openings  38  through the film  14  into the outer enclosed space  36  ensures that the openings  38  will not become blocked by purge or by the meat product itself.  
         [0024]    Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.