MXPA00009710A - Modified atmosphere package with accelerated reduction of oxygen level in meat compartment - Google Patents

Abstract

A modified atmosphere package (10) includes first and second compartments separated by a partition member that is substantially permeable to oxygen. The first compartment contains an oxygen scavenger (28) activated with an oxygen scavenger accelerator. The second compartment contains a retail cut of raw meat (26). Various techniques are employed to rapidly reduce the oxygen level in the second compartment below pigment sensitive levels so that the growth of metmyoglobin is inhibited. Some of these techniques increase the flow of oxygen from the second compartment to the first compartment through the partition member, while other techniques directly absorb oxygen within the second compartment.

Description

PACKAGE WITH MODIFIED ATMOSPHERE WITH ACCELERATED REDUCTION OF THE LEVEL OF OXYGEN IN THE COMPARTMENT FOR MEAT FIELD OF THE INVENTION The present invention relates generally to modified atmosphere packages for storing food such as raw meat. More particularly the invention relates to a modified atmosphere package having two compartments, one containing the meat, separated by a substantially permeable partition member, and refers to techniques for rapidly reducing the level of oxygen in the compartment containing the meat, below sensitive levels of the pigment in such a way that the production of metamioglobin is inhibited.

BACKGROUND OF THE INVENTION Containers have been used for a long time to store and transfer perishable food before presenting the food to a market where it will be bought by the consumer. After perishable foods, such as meats, fruits and vegetables, are gathered or harvested, they are placed in containers to preserve those foods for as long as possible.

By maximizing the time in which the food remains in the containers, the profitability of all the entities in the distribution chain is increased, minimizing the amount of deterioration. The environment around which food is preserved is a critical factor in the conservation process. Not only is it important to maintain an adequate temperature, but it is also significant, as such, the molecular and chemical content of the gases surrounding the food. By providing an appropriate content of gases to the environment surrounding the food, the food can be best preserved when kept at the proper temperature or even when exposed to variations in temperature. This gives the food producer some assurance that after the food goes out of control, the food will be in an acceptable condition when it reaches the consumer. Packaging systems with modified atmosphere, for one type of food, raw meats, expose these raw meats to oxygen (02) or extremely high or extremely low levels. Packaging systems that provide extremely low oxygen levels are generally preferable because it is well known that the fresh quality of the meat can be preserved for longer under anaerobic conditions than under aerobic conditions.

Maintaining low oxygen levels minimizes the growth and multiplication of aerobic bacteria. An example of a system with low oxygen level is described in U.S. Patent No. 5,698,250 to DelDuca et al ("DelDuca"), which is incorporated herein by reference in its entirety. Figures 1 and 2 of DelDuca are reproduced herein as Figures 1 and 2. Referring to Figures 1 and 2, DelDuca describes a package with modified atmosphere 10, which includes an outer container 12 composed of an oxygen barrier material. and an inner container 14 composed of a material substantially permeable to oxygen. The inner container 14 is preferably composed of a tray 16 of polystyrene foam and a jacket 18 with stretch film. The tray 16 contains a cut of raw meat for retail sale 26. An oxygen scavenger 28 is located between the inner container 14 and the outer container 12. To create a modified atmosphere, in the package 10, DelDuca employs the following method. First, the meat 26 is placed inside the inner container 14 and subsequently the inner container 14 is sealed. Second, the inner container 14 is inserted into the outer container 12. Third, without using any evacuation, the outer container 12 is flooded with an appropriate mixture of gases, such as 30 percent carbon dioxide and 70 percent nitrogen , to remove most of the oxygen from the outer container 12. Fourth, the outer container 12 is sealed. Fifth, the oxygen scavenger 28 is activated and used to absorb any amount of residual oxygen that is contained in the package 10. The DelDuca method is based on the activation of the oxygen scavenger 28 for Quickly absorb residual oxygen. Figure 2 identifies four sources, or zones, of oxygen, that exist within the package 10. The zone I is the volume of oxygen that lies between the outer container 12 and the inner container 14; Zone II is the volume of oxygen that is inside the inner container 14; Zone III is the volume of oxygen that is inside the cells of the foam tray 16; and zone IV is the volume of oxygen found within meat 26, which is believed to be minimal, with the exception of ground meats. The oxygen scavenger 28 is located in zone I. In the DelDuca method, described above, the step of flooding the outer container 14 reduces the oxygen level within the package 10 to levels of about 0.05 to 5 percent. At these oxygen levels, especially at the lower end of the previous interval (0.05 to 2 percent), metamyoglobin can be formed very quickly. Metamyoglobin is a substance that causes the meat to change to an undesirable brown color. Metamyoglobin is formed very slowly at oxygen levels above 2 percent and below 0.05 percent, but very quickly between these oxygen levels. Therefore, it is important to pass the meat located in zone II through the pigment-sensitive oxygen range (0.05 to 2 percent), very quickly, for example, in less than about two hours. Although DelDuca contemplates flooding the inner container 14, the existing technology will generally not flood zone II below the range of pigment-sensitive oxygen. Therefore, even if the inner container 14 is flooded, the oxygen level in zone II must still be passed quickly through the range of pigment-sensitive oxygen. In DelDuca, after the outer container 12 is sealed, the oxygen remaining in zone II (inside the inner container 14) passes, substantially but not 100 percent, through the permeable material of the inner container 14 and is rapidly absorbed by activated oxygen scavenger 28, which is located in zone I. The faster the velocity of the oxygen outflow from zone II into zone I, the faster the level of oxygen in zone II can pass through the range of oxygen sensitive to pigments. The present invention is focused on techniques for improving the rate of oxygen outflow, from zone II to zone I. Furthermore, the present invention is focused on techniques for directly absorbing oxygen from zone II before the oxygen passes to Zone I SUMMARY OF THE INVENTION In accordance with one embodiment of the present invention, a package with modified atmosphere includes first and second compartments separated by a partition member that is substantially permeable to oxygen. The first compartment contains an activated oxygen scavenger with an oxygen scavenger accelerator. The second compartment contains a raw meat cut for retail sale. To improve the flow of any amount of oxygen that is in the second compartment, from the second compartment to the first compartment, one or more features can be incorporated in the dividing member to improve its permeability. For example, if the dividing member is composed, in part, of a wrap with stretch film, such as polyvinyl chloride (PVC), the wrap with stretch film may be provided with a plurality of holes in the form of relatively large holes, small holes, or microperforations. If the holes are relatively large, for example, having a diameter ranging from approximately 0.125 cm (0.125 inches) to approximately 1.91 cm (0.75 inches), the holes are preferably covered with a label composed of olefin in TYVEK ™ glued yarn. , or paper, to prevent the juice of the meat leaking out of the second compartment, through the holes, and to prevent the desiccation and contamination of the meat. The label adheres to the wrap with stretch film, in areas around the holes. TYVEK bonded yarn olefin is fully permeable to oxygen, so no additional holes are formed in the TYVEK label. However, if the label is composed of paper or plastic, materials that are somewhat impervious to oxygen, small holes or microperforations are formed on the label. Various other features can be incorporated in the dividing member to increase its permeability, including a breathing or capillary tube; reliefs; a film or self-sealing coating, to allow the creation of temporary holes in the dividing member; a Landec type film that has a permeability that can be controlled by heat, light or some other source of energy; and two layers of wrap with stretch film, perforated. If the dividing member includes a wrap with stretch film, wrapped around a foam tray, a section of the tray wall may be composed of open or perforated cell foam. This section of the tray wall is left uncovered with the wrapping with stretch film, to allow oxygen from the second compartment to pass easily through both the wrap with stretch film and through the exposed section of the wall of the tray. the tray. Other techniques for rapidly reducing the oxygen level in the second compartment concern less than changing the structure of the dividing member. For example, a second oxygen scavenger may be placed within the second compartment, removed from the meat, or the scavenger material may be dispersed in the wall of the tray. Alternatively, carbon dioxide pellets can be placed inside the second compartment, removed from the meat. The pellets serve as a flood agent that forces the oxygen out of the second compartment. Also, the finished package can be irradiated to create ozone (03) inside the package. Ozone is more easily removed by the oxygen scavenger. The above summary of the present invention is not intended to represent each embodiment or each aspect of the present invention. This is the purpose of the figures and detailed description presented below.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed description and with reference to the drawings, in which: Figure 1 is an isometric view of a package with modified atmosphere; Figure 2 is a sectional view, taken, in general, along the line 2-2 of Figure 1; Figure 3 is an enlarged view, taken, in general, along the circular portion 3 of Figure 2; Figure 4 is a schematic side view of a system for manufacturing the package with modified atmosphere; Figure 5a is a top view of a section of the modified atmosphere package, with a portion of the outer package removed to reveal an inner package having a stretch film wrap, with a hole covered by a TYVEK patch; Figure 5b is a sectional view, enlarged, taken, in general, along the line 5b-5b of Figure 5a; Figure 6a is a top view of the modified atmosphere package, with a portion of the outer package removed to reveal an inner package having a perforated, stretchable film wrap; Figure 6b is a sectional view, enlarged, taken, in general, along the line 6b-6b of Figure 6a; Figure 6c is an enlarged view, similar to Figure 3, but showing small holes formed in a wall of the tray, - Figure 7a is a plan view of a section of the package with modified atmosphere, with a portion of the package exterior removed to reveal an inner package that has wrap with stretch film, with a hole covered by a paper or perforated plastic patch; Figure 7b is a sectional view, enlarged, taken, in general, along the line 7b-7b of Figure 7a; Fig. 8 is an enlarged view, similar to Fig. 3, but showing an inner pack having a wrap with stretch film composed of two: perforated film layers; Figure 9 is an enlarged view, similar to Figure 3, but showing a capillary mounted to the interior package of the modified atmosphere package; Fig. 10 is an enlarged view, similar to Fig. 3, but showing an inner package having a wrap with stretchable, embossed film; Fig. 1a is an enlarged side view, similar to Fig. 3, but showing perforated holes through an inner pack wrap, composed of standard stretch film coated with a self-sealing layer of low molecular weight wax or polymer; Figure 11b is an enlarged side view similar to figure Ia, but showing the holes plugged by the self-sealing layer; Fig. 12 is an enlarged side view, similar to Fig. 3, but showing a wall section of the non-enveloped tray formed of foam with open or perforated cells; Figure 13 is an enlarged side view, similar to Figure 3, but showing a package for oxygen removal fixed to the tray wall and with oxygen scavenging material dispersed within the tray wall; Fig. 14 is an enlarged top view, similar to Fig. 3, but showing pellets of carbon dioxide along the wall of the tray; and Figure 15 is a top view of a section of the modified atmosphere package, with a portion of the outer package removed to reveal an inner package having a stretch film wrap, with a hole covered by a Landec-type film patch. Although the invention is susceptible to various modifications and alternative forms, certain specific embodiments thereof have been presented by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular forms described. On the contrary, the intention is to cover all the modifications, equivalent and alternatives that fall within the spirit and scope of the invention as defined by the appended claims.

DESCRIPTION OF ILLUSTRATIVE MODALITIES Returning now to the drawings, FIGS. 1-3 represent a package with modified atmosphere 10, including an outer package 12 and an inner package 14. The term "package" as used herein, will be defined as any means for contain raw meat, including a container, carton, box, package, receptacle, tray, flat structure, bag, wrapping film, etc. At least a portion of the inner pack 14 is permeable to oxygen. The inner package 14 includes a semirigid, conventional plastic tray 16, thermoformed from a sheet of polymeric material that is substantially permeable to oxygen. Exemplary polymers that can be used to form a tray 16 that does not represent a barrier include polystyrene foam, cellulose pulp, polyethylene, polypropylene, etc. In a preferred embodiment the polymer sheet used to form the tray 16 is substantially comprised of polystyrene foam and has a thickness ranging from about 0.25 cm (100 mils) to about 0.76 cm (300 mils). The use of a common polystyrene foam tray 16 is desirable because it is more widely accepted by the consumer. The inner package 14 further includes a wrap with stretch film or cover 18 substantially composed of a polymeric material, such as polyvinyl chloride (PVC), which is substantially permeable to oxygen. Like a foam tray, a wrap with stretch film, made of PVC, has greater acceptance by the consumer. In a preferred embodiment, the stretch film used to form the cover 18 contains additives that allow the film to adhere to itself, have a thickness ranging from about 0.0013 cm (0.5 mil) to about 0.004 cm (1.5 mils). inch), and has an oxygen permeability rate greater than about 1000 cubic centimeters per 645.16 square centimeters (100 square inches) in 24 hours. Preferably the film has an oxygen permeability rate of greater than about 7000 cubic centimeters per 100 square inches in 24 hours and, most preferably, has an oxygen permeability index of greater than about 10,000 cubic centimeters per cubic meter. 645.16 square centimeters (100 square inches) in 24 hours. One film for stretch application, preferred, is the commercially available Resinite ™ meat film from Borden Packaging and Industrial Products of North Andover, Massachusetts. The tray 16 is, in general, rectangular in shape and includes a bottom wall 20, a continuous side wall 22 and a continuous edge or flange 24. The continuous side wall 22 encompasses the bottom wall 20 and extends upwards and downwards. outside from the bottom wall 20. The continuous edge 24 encompasses an upper edge of the continuous side wall 22 and projects laterally outward therefrom. A food article such as a cut of raw meat for retail sale 26 is located in a rectangular compartment defined by the bottom wall 20 and by the continuous side wall 22. The raw meat can be of any animal protein including meat from beef, pork, lamb, turkey, venison, fish, etc. Before completely wrapping the tray 16 with the cover 18, the partially formed interior package 14 can be flooded with an appropriate mixture of gases, typically a mixture of about 30 percent carbon dioxide and about 70 percent nitrogen, to reduce the oxygen level in the inner pack 14 to an amount of about 1.5 to 5.0 percent. The preceding gas mixture displaces the oxygen that is inside the inner package 14 during the flooding operation. After flooding the inner package 14, the tray 16 is wrapped manually or automatically with the cover 18. The cover 18 is wrapped over the cut of raw meat for retail sale 26 and around, both of the side wall 22 and of the bottom wall 20 of the tray 16. The free ends of the cover 18 overlap along the underside of the bottom wall 20 of the tray 16 and, due to the inherent, adherent characteristic of the cover 18, these overlapped free ends adhere to each other to hold the cover 18 in place. If desired, the wrapped tray 16, that is, the inner package 14, can be passed over a hot plate to thermally melt the free ends of the cover 18, each other, and thereby prevent these free ends from crumbling potentially. The outer package 12 is preferably a flexible polymer bag composed of a plastic material, single-layer or multi-layer, which is substantially permeable to oxygen. The polymeric bag 12 may include, for example, a coextruded, multilayer film containing ethylene vinyl chloride (EVOH), or including an oriented polypropylene (OPP) core coated with an oxygen barrier coating, such as chloride. of polyvinylidene and further laminated with a layer of sealing material such as polyethylene, to facilitate thermal sealing. In a preferred embodiment, the polymer bag 12 is comprised of a barrier film, coextruded, commercially available as product No. 325C44-EX861B from PrintPack, Inc. of Atlanta, Georgia. The barrier film, co-extruded, has a thickness ranging from about 0.005 cm (2 mils) to about 0.015 cm (6 mils) and having an oxygen permeability rate of less than about 0.1 cubic centimeters per 645.16 centimeters square (100 square inches) in 24 hours. Before sealing the peripheral edges of the polymer bag 12, the inner pack 14 is placed inside the polymer bag 12. Also, the bag 12 is flooded with an appropriate mixture of gases, typically with an amount of about 30 percent dioxide of carbon and about 70 percent nitrogen, to reduce the level of oxygen found in the bag 12 to an amount of about 0.05 to 5.0 percent. After flooding the bag 12, but before still sealing the bag 12, an oxygen scavenger / absorber 28 is placed in the bag 12, external to the sealed inner pack 14. The bag 12 is then sealed. The oxygen scavenger 28 is designed to reduce the level of oxygen in the bag 12 at a sufficient rate to prevent discoloration (eg, brown coloration) of the raw meat 26. Many factors influence the color stability of the raw meat, but it has been found that The reduction in oxygen level, from the level of 0.05 to 5.0 percent described above, to less than about 0.05 percent in 90 minutes, works for all types of raw meat. If there is still oxygen in the bag 12 after this period of time, the oxygen scavenger 28 absorbs any oxygen remaining in the bag 12 and any oxygen that may still be trapped inside the inner container 14 in order to reduce the level of oxygen in the bag 12. oxygen in the bag 12 to about zero percent, in 24 hours. The oxygen scavenger 28 also absorbs any amount of oxygen that could permeate into the bag 12 from the environment. To increase the rate of oxygen uptake, the oxygen scavenger is activated with an oxygen uptake accelerator, in the form of a predetermined amount of the activating agent or through another medium, just before being placed in the bag 12. The accelerator of the oxygen uptake is preferably selected from the group consisting of water or aqueous solutions of acetic acid, citric acid, sodium chloride, calcium chloride, magnesium chloride, and copper. Additional information concerning the oxygen scavenger 28, the oxygen uptake accelerator, and the means for introducing the oxygen uptake accelerator, to the oxygen scavenger 28, can be obtained from the apption Serial No. 08 / 856,448 filed on May 14, 1997, entitled "Accelerator of an Oxygen Eliminator" incorporated herein by reference. In Figures 1-3 the oxygen scavenger 28 is illustrated as a package or label that is inserted into the bag 12 before sealing the bag 12. Alternatively a material for the removal of oxygen, the polymer or polymers used can be added. to form the outer package 12 so that the oxygen removal material is integrated into the outer package 12 itself. The cut of raw meat for retail sale 26 which is contained within the package with modified atmosphere 10 takes on a purple-red color when the oxygen is removed from the interior of package 10. The package with modified atmosphere 10 with the introduced meat can now be stored in a refrigeration unit for several weeks before being offered for sale to a grocery store. A little earlier (for example, less than one hour) before being displayed in the grocery store, the inner pack 14 is removed from the polymer bag 12 to allow oxygen from the environment to pierce the non-barrier tray 16 and the non-barrier cover 18. red-purple color of raw meat 26 changes rapidly or "presents freshness", to a generally acceptable bright red color, when raw meat 26 is oxygenated by exposure to air. Figure 4 illustrates a modified atmosphere package system, used to produce the modified atmosphere package 10 in Figures 1-3. The packaging system integrates several different technologies and commercially available, to provide a modified atmosphere to cuts of raw meat for retail sale. The basic operations performed by the packaging system are described below with reference to Figure 4. The packing process begins at a thermoforming station 30 where a tray 16 is produced by thermoforming in a conventional manner, from a sheet of polystyrene or other non-barrier polymer, using conventional equipment for thermoforming. The thermoforming equipment typically includes a male die member 30a_ and a female die cavity 30b. As is well known in the thermoforming art, the tray 16 is produced by thermoforming by inserting the male die member 30a into the female die cavity 30b with the polymeric sheet placed therebetween. The thermoformed tray 16 continues to a station 32 for loading products, wherein the tray 16 is filled with a food product such as a cut of raw meat for retail sale 26. The tray 16 is then manually carried or transported over a conveyor 34 to a station 36 for conventional stretch wrapping wherein a stretch film 18 is wrapped around the tray 16 to enclose, therein, the cutting of meat for retail 26. The wrapped tray 16 forms the inner package 14. Just before sealing the tray 16 filled with meat, in the stretch wrapping station 36, the tray 16 is flooded with a mixture of carbon dioxide and nitrogen, to reduce the oxygen level in the tray 16 to an amount from approximately 1.5 to 5.0 percent. The mixture of carbon dioxide and nitrogen emanates from a hollow tube or rod 40 for gas supply, conventional, fed by a gas tank (not shown). The station 36 for stretch wrapping can be implemented with a compact, semi-automatic, stretch wrapping apparatus, commercially available from Hobart Corporation of Troy, Ohio. Subsequently, the inner package 14 flooded and sealed, proceeds to a station 42 for forming, filling and sealing, at high speed, which can be implemented with a horizontal machine for forming, filling and sealing of high speed, Fuj i-Formost, commercially available with model No. FW-3700 of Formost Packaging Machines, Inc. of Woodinville, Washington. The inner package 14 can be transported to the forming, filling and sealing station 42, by a conveyor 44. In the forming, filling and sealing station 42, a continuous tape 46 of oxygen barrier film, coming from a roll 47 it is accommodated to move along the direction of movement of the inner pack 14. The continuous film tape 46 is fed into a conventional shaped box forming a section 48 of the continuous tape 46 in a tubular configuration encompassing the inner package 14. The tube-like section 48 of the continuous tape 46 is thermally sealed along a lower flap 50 and thermally sealed at one end 52 by a pair of heat sealing bars 54 which They oscillate vertically or similar. Just before sealing the other end 56 of the tubular continuous section 48, to complete the formation of the polymer bag 12, the continuous belt section 48 is flooded with an appropriate mixture of gases, typically about 30 percent carbon dioxide and about 70 percent nitrogen, to reduce the level of oxygen in the bag 12 to approximately the amount of 0.5. to 5.0 percent. The mixture of carbon dioxide and nitrogen emanates from a hollow tube or rod 58 for gas supply, conventional, fed by a gas tank (not shown). After flooding the continuous belt section 48, but before still sealing the end 56, the oxygen scavenger / absorber 28 is placed in the continuous belt section 48 external to the sealed inner container 14 and the oxygen scavenger 28 is activated with an accelerator of oxygen uptake. The end 56 is then transported between the hot sealing rods 54 and sealed thereto, to complete the formation of the bag 12. In addition to thermally melting the continuous belt section 48 at the end 56, the hot sealing rods 54 the continuous belt section 48 is provided at the end 56 to separate the bag 12 from the next upstream belt section, which is being formed to produce another bag. The sealed bag 12 substantially has the form of a sealed bubble or untwisted wrap that contains the inner pack 14 and provides a sealed modified atmosphere surrounding the inner pack 14. The oxygen scavenger 28 decreases the level of oxygen found in the bag. pack 10, from the oxygen level of 0.05 to 5.0 percent, previously described, to less than about 0.05 percent, in a period of time of approximately 90 minutes. Although the oxygen scavenger 28 is depicted in FIG. 4 as a package or label inserted into the polymer bag 12, an oxygen scavenger may alternatively be integrated into the polymers used to form the bag 12. A preferred oxygen scavenger is an oxygen absorber package called FreshPax ™ commercially available from MultiSorb Technologies, Inc. (formerly Multiform Dessicants Inc.) of Buffalo, New York. The modified atmosphere packaging system of Figure 4 can produce modified atmosphere packages at cycle rates ranging from about 1 to 60 packages per minute. The maximum speeds per cycle, which can be achieved by the system of Figure 4, are significantly greater than the speeds per cycle that can be achieved through prior art systems. Obtaining high speeds per cycle is largely due to the fact that the packaging system of Figure 4 is based on the use of simple, high speed, commercially available forming, filling and sealing equipment, opposite to the evacuation equipment, slower, used by the systems of the prior art. Reducing the oxygen levels in the modified atmosphere pack 10 by first flooding the pack 10 and then subsequently introducing the activated oxygen scavenger 28 into the pack 10, is significantly faster and more cost effective, than relying on slow evacuation techniques . Referring to Figure 2, the region outside the inner package 14 and within the outer package 12, defines a first compartment or zone I, while the region within the interior package-14 defines a second compartment or zone II. The inner package 14 by itself forms a dividing member between the first and second compartments. As discussed above, after the outer package 12 is sealed during the manufacturing process, it is desirable to improve the oxygen flow from the second compartment to the first compartment, such that any amount of oxygen found in the second compartment can be absorbed quickly by the oxygen scavenger, activated, 28, which is in the first compartment. The improved oxygen flow, in turn, minimizes the time during which the meat in the second compartment is exposed to oxygen levels in the range sensitive to pigments (0.05 to 2 percent). By minimizing meat exposure to oxygen levels in the pigment-sensitive range, the formation of metamyoglobin is inhibited which can cause the meat to change to an undesirable brown color. The present invention provides several features that can be incorporated into the inner package 14 to increase its oxygen permeability up to speeds greater than about 7000 cubic centimeters per 645.16 square centimeters (100 square inches) in 24 hours and, more preferably, to higher ratios of approximately 10,000 cubic centimeters per 645.16 square centimeters (100 square inches) in 24 hours. These high rates of oxygen permeability allow the activated oxygen scavenger 28, which is in the first compartment, to reduce the oxygen level in the second compartment (interior package 14) to less than about 0.05 percent, in a a period of time less than about two hours and typically about 90 minutes after the package 10 is sealed. The characteristics that increase the permeability can be used separately or in combination. In addition to increasing the oxygen permeability of the inner package 14, the present invention focuses on other issues such as preventing the juices of the meat (to purge) from escaping from the inner package 14, preventing the drying of the meat and preventing Bacterial contamination of meat. The leakage of the juices from the inner pack is a significant disadvantage of the system proposed by the US Pat. No. 5,667,827 to Breen et al. Referring to Figs. 5a-b, 6a-b and 7a-b, if the inner pack 14 is partially composed of a wrap with stretch film 18 such as polyvinyl chloride (PVC), the wrap with stretch film 18 may be provided. from one or more relatively large holes 60 (figures 5a-b and 7a-b) or from a plurality of small holes or micro-perforations 62 (Figures 6a-b). The holes 62 in Figure 6a can represent either small holes or microperforations. For the holes to be effective, they must communicate with the interior of the package 14. Accordingly, the holes should be located along the portion of the wrap with stretch film 18, generally above the bottom wall 20. of the tray and inside the side wall 22 of the tray, continuous. The holes can be made during the manufacture of the wrap with stretch film 18 or just before covering the tray 16 with the wrapper 18. If the holes are relatively large holes 60 as in FIGS. 5a-b and 7a-b, for example, that have a diameter ranging from about 0.125 cm (0.125 inches) to about 1.91 cm (0.75 inches), the holes are preferably covered with a patch or label 66 composed of olefin in TYVEK "31 glued yarn, paper or plastic, to prevent meat juice leaks out of the second compartment, through the holes, and to prevent drying and contamination of the meat TYVEK stuck olefin is commercially available from DuPont of Wilmington, Delaware. perforate in the wrap with stretch film 18 before the label 66 is applied. The tag 66 could be decorative or could provide information regarding the io Using a food grade adhesive, the label 66 adheres to the wrap with stretch film 18 in areas around the holes. In a mode shown in the best manner in Figure 5b, the tag 66 is circular, has an outside diameter of 1.91 cm (0.75 inches), and has adhesive applied in an area confiby the outside diameter of 1.91 cm (0.75 inches) and an inner diameter of approximately 0.95 to 1.3 cm (from 0.375 to 0.5 inches). The area inside the inner diameter is free of adhesive. With respect to a TYVEK tag (Figure 5a-b), since the TYVEK bonded spinel olefin is fully permeable to oxygen, no additional holes are formed in the TYVEK tag. When the TYVEK label is adhered to the wrapping with stretch film, the food grade adhesive does not apply to the portion of the label covering the holes, so that the oxygen permeable pores on the label are not covered by the label. the adhesive With respect to a paper or plastic label (Figure 7a-b), which is somewhat impervious to oxygen, small holes or additional microperforations 70 are formed on the label (Figure 7b). Although a label 66 is preferred over the relatively large holes in the wrap with stretch film 18, the label is not absolutely necessary as long as care is taken to avoid tilting the package 10 to a degree that allows the juice the meat leaks out of the inner package 14. - On the other hand, if the holes are small holes or microperforations 62 (figure 6a) having a diameter ranging from about 0.01 cm (0.004 inches) to about 0.08 cm (0.030 inches) ), a label is not preferred, because the holes are of a diameter small enough so that the surface tension prevents the juice of the meat from passing through the holes. In the illustrated embodiment the small holes 62 are applied to the largest portion of the casing 18 located within the side wall 22 of the tray and are arranged in a rectangular network. Adjacent holes are approximately 2.54 cm (one inch) apart. Alternatively, as shown in Figure 6c, the small holes 64 can be formed in an unshielded section of the side wall 22 of the tray 16. As shown in Figure 8, if larger perforations are desired, the envelope with stretchable film 18b can be composed of two perforated layers in which perforations 62a of one layer are traversed (non-aligwith) with respect to perforations 62b of the other layer. The perforations traversed create a tortuous path that prevents the leakage of the juices from the meat of the inner package 14. Experiments have been discovered in which all the previous options concerning the application of holes and labels, in the wrap with stretch film 18, successfully increase the oxygen permeability of the inner package 14, up to indexes that allow the activated oxygen scavenger 28, which is in the first compartment, to reduce the oxygen level in the second compartment (inner package 14) to less than about 0.05 percent, in a period of time less than about two hours after package 10 is sealed. Specifically, the experiments analyzed the following options: a hole having a diameter of 0.32 cm (0.125 inches), a 0.64 cm (0.25 inch) hole, a 0.95 cm (0.375 inch) hole, four 0.125 inch (0.125 inch) holes with TYVEK label, a 0.64 cm (0.25 inch) hole with TYVEK tag, a 0.75 cm (0.375 inch) hole with TYVEK tag, a 1.75 cm (0.75 inch) hole with a TYVEK tag, a 1.91 cm (0.75 inch) hole with a paper label that is 15 a small holes, a 1.91 cm (0.75 inch) hole with paper label that has 12 small holes, 6 small holes, 12 small holes, and microperforations through the wrap with stretch film. Each of the above options helped wrap with stretchable film, get high, acceptable rates of oxygen permeability. Several other features can be incorporated into the dividing member to increase its permeability. Figure 9 depicts a breathing or capillary tube 72 inserted through the stretch film wrap 18 and the side wall 22 of the tray 16 and into the interior of the tray. Figure 10 depicts reliefs 74 formed in the wrap with stretch film 18. The embossed areas of the stretch wrap are thinner than other areas of the stretch wrap and, therefore, exhibit higher rates of oxygen permeability . Figs. 1a and 11b depict a wrap with stretch film 18a including a layer of PVC 67 and a self-sealing thin layer 68 of wax or food-grade polymer having a low molecular weight. The self-sealing layer 68 can be applied to the PVC layer 67 through conventional spraying techniques or by conventional application and metering rollers of a printing press. Since the layer 68 is self-sealing, the holes 76 formed in the envelope 18a are only temporary and are capped by the self-sealing layer 68 over time (Figure 11b). The holes 76 are formed in the envelope 18a during the manufacturing process before sealing the package 10 and are exposed sufficiently to allow the oxygen scavenger 28 to reduce the oxygen level in the inner package 14 to less than about 0.05 percent. in a time less than about two hours after the package 10 is sealed. As shown in Figure 11b, the holes 76 are preferably plugged before shipping the full package of meat 10 to eliminate the possibility of leakage of the juices from the meat of the inner package 14. In another embodiment, the wrap with stretch film 18 in figures 1-3 is composed of a Landec type film produced through the process known as Intellimer, which has a permeability that can be controlled by heat , light or some other source of energy.The film is normally in an amorphous state, substantially impermeable, and can be temporarily changed to a crystalline, highly permeable, through the application of the energy source. The energy source is applied to the Landec type film during the manufacturing process and for a sufficient period of time after the package 10 is sealed, to allow the oxygen scavenger 28 to reduce the level of oxygen found in the second compartment (interior package 14) to less than about 0.05 percent, in less than about two hours. Alternatively, as shown in Figure 15, the stretch film wrap 18 can be composed of conventional polyvinyl chloride and include a hole 73 covered by a label 75 composed of a Landec type film. In yet another embodiment shown in Figure 12, the inner pack 14 includes a wrap with stretch film 18 partially wrapped around a foam tray 16a having an exposed section (not wrapped) composed of open cell or perforated polystyrene foam. . Section 77 of open or perforated cell foam, of tray 16a, is highly permeable to oxygen and assists inner package 14 to achieve a higher oxygen permeability ratio than an inner package composed entirely of a closed cell foam. To take advantage of the section 77 of open-cell or perforated, highly permeable foam section of the tray 16a, the cover of the stretch-film casing 18 on the bottom of the tray is partial to allow the oxygen of the inner package 14 pass through the foam section of open or perforated cells. Other possible techniques for rapidly reducing the oxygen level in the second compartment (inner package 14) are related to less than altering the structure of the tray 16 or the wrap with stretch film 18. For example, as shown in Figure 13, a second oxygen scavenger 78 can be placed inside the inner package 14, removed from the meat 26. Alternatively or additionally, the oxygen scavenging material 79 can be dispersed in the wall of the tray 16. Like the scavenger Oxygen 28, the oxygen scavenger 78 is preferably activated with an oxygen scavenger accelerator, just before sealing the inner package 14 during the manufacturing process. To keep the oxygen scavenger 78 separate from the meat 26, the oxygen scavenger 78 can be adhered by a food grade adhesive to one side of the tray 16 or it can be housed in a highly permeable housing along one side of the tray. the tray 16. The oxygen scavenger 78 directly absorbs any amount of oxygen present in the second compartment (interior package 14) and does not require oxygen to pass from the second compartment to the first compartment, to be absorbed. Alternatively, as shown in the figure 14, carbon dioxide pellets 80 (dry ice) can be placed inside the inner package 14 and removed from the meat 26. The pellets 80 serve as a flood agent which forces the oxygen out of the inner package 14 inclusive after the package 10 is sealed. Still in another embodiment, the sealed package 10 is irradiated to create ozone (03) within package 10. Ozone is more easily removed than oxygen (02) by the oxygen scavenger 28 and therefore both the oxygen levels within the second compartment (interior package 14) containing the meat 26 are reduced more rapidly. In effect, the carbon dioxide pellets 80 and the creation of ozone, each increase the rate of oxygen outflow from the second compartment (interior package 14) to the first compartment. Although the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes can be made thereto, without departing from the spirit and scope of the present invention. Each of these modalities and obvious variations thereof are contemplated as falling within the spirit and scope of the claimed invention, which are presented in the following claims.

Claims (25)

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A package with modified atmosphere, characterized in that it comprises: a first and second compartments separated by a partition member substantially permeable to oxygen, the first compartment contains an oxygen scavenger activated with an oxygen scavenger accelerator, the second compartment contains a meat cut raw for retail sale; and, means for enhancing permeability in order to increase a permeability index of the dividing member to an index that exceeds approximately 7,000 cubic centimeters per 645.16 square centimeters (100 square inches) in 24 hours, such that the formation of metamioglobin in the raw meat .

The package according to claim 1, characterized in that the dividing member includes the means for enhancing the permeability.

3. The package according to claim 2, characterized in that the means for enhancing the permeability includes a hole formed in the dividing member and covered by a label, the label is affixed to the dividing member in position adjacent to the needle.

4. The package according to claim 3, characterized in that the label is composed of an olefin in TYVEK glued yarn.

5. The package according to claim 3, characterized in that the label is composed of paper or plastic and is perforated.

6. The package according to claim 3, characterized in that the label is composed of a Landec type label, which has a controlled permeability by means of an energy source.

The package according to claim 3, characterized in that the dividing member includes a wrap with stretch film and the hole is formed in that wrap.

The package according to claim 3, characterized in that the hole has a diameter ranging from about 0.32 cm (0.125 inches) to about 1.91 cm (0.75 inches).

The package according to claim 2, characterized in that the means for enhancing the permeability includes raised areas on the dividing member, which have a higher rate of permeability than the areas, which are not in relief, of the dividing member .

10. The package according to claim 1, characterized in that the dividing member includes a tray covered by a wrap with stretch film, the tray and wrap with stretch film enclose the second compartment, the tray has a bottom wall and a wall continuous side extending from the bottom wall, the wrap with stretch film includes the means for enhancing the permeability, the means for enhancing the permeability includes perforations formed in the wrap with stretch film.

The package according to claim 10, characterized in that the perforations have a diameter ranging from approximately 0.01 (0.004 inches) to approximately 0.08 cm (0.030 inches), so that the surface tension prevents the juices of the meat leaking through the perforations.

The package according to claim 11, characterized in that the wrap with stretch film includes first and second film layers, each of which contains the perforations, the perforations in the first layer are traversed of the perforations that are found. in the second layer, to create a tortuous path that prevents the juices of the meat from passing through the wrap with stretch film.

The package according to claim 10, characterized in that the wrap with stretch film includes a layer of film that is applied with stretch and a self-sealing layer., each of which is substantially permeable to oxygen, the perforations initially pass through the layer of stretch-applied film and the self-sealing layer and are subsequently covered by the self-sealing layer.

The package according to claim 13, characterized in that the stretch film layer is composed of polyvinyl chloride and the self-sealing layer is composed of a low molecular weight wax or polymer.

15. The package according to claim 1, characterized in that the dividing member includes a tray for meat, which has a wall, the tray includes the means of enhancing permeability, the means of intensification of permeability includes a capillary mounted to the wall of the tray and extends from the second compartment to the first compartment.

16. The package according to claim 15, characterized in that the dividing member includes a wrap with stretch film that covers the tray.

17. The package according to claim 1, characterized in that the dividing member includes a meat tray and a cover enclosing the second compartment, the tray has a wall, the cover covers the tray and leaves a section of the wall exposed, the tray includes the permeability enhancement means, the permeability enhancement means is selected from a group consisting of small holes in the exposed section of the tray wall, perforations in the exposed section of the tray wall , and open cell foam in the exposed section of the tray wall.

18. The package according to claim 17, characterized in that the tray is composed of polystyrene foam.

19. The package according to claim 18, characterized in that the cover includes a wrap with stretch film.

20. The package according to claim 1, characterized in that the means for enhancing the permeability includes carbon dioxide pellets, contained in the second compartment, for flooding the oxygen into the second compartment out of the second compartment and through the member. dividing, for absorption by the oxygen scavenger.

21. The package according to claim 20, characterized in that the dividing member includes a tray having a wall of the tray, the carbon dioxide pellets are located on the wall of the tray, and separated from the raw meat.

22. A package with modified atmosphere, characterized in that it comprises a first and second compartments separated by a partition member substantially permeable to oxygen, the first compartment contains a first activated oxygen scavenger with an oxygen scavenger accelerator, the second compartment contains a cut-off of raw meat for retail sale, and additionally includes means for the removal of oxygen, additional, located outside the first compartment, to absorb the oxygen that is inside the second compartment.

23. The package according to claim 22, characterized in that the additional means for the elimination of oxygen, includes a second oxygen scavenger, contained in the compartment and separated from the raw meat.

24. The package according to claim 23, characterized in that the dividing member includes a tray having a wall of the tray, and in that the second oxygen scavenger is fixed to the tray wall.

25. The package according to claim 22, characterized in that the dividing member includes a tray having a tray wall, and because the additional means for oxygen removal includes an oxygen scavenging material dispersed within the wall of the tray. tray.