Modified Atmosphere Package with Accelerated Reduction of Oxygen Level in Meat Compartment

Home , Modified atmosphere, Oxygen scavenger

Europäisches Patentamt *EP001071619B1* (19) European Patent Office

Office européen des brevets (11) EP 1 071 619 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.7: B65D 81/26 of the grant of the patent: 09.11.2005 Bulletin 2005/45 (86) International application number: PCT/US1999/006651 (21) Application number: 99912908.3 (87) International publication number: (22) Date of filing: 26.03.1999 WO 1999/051508 (14.10.1999 Gazette 1999/41)

(54) MODIFIED ATMOSPHERE PACKAGE WITH ACCELERATED REDUCTION OF OXYGEN LEVEL IN MEAT COMPARTMENT VERPACKUNG MIT DURCH BESCHLEUNIGTE SAUERSTOFF-REDUKTION IN EINEM FLEISCHBEHÄLTNIS VERÄNDERTER ATMOSPHÄRE CONDITIONNEMENT SOUS ATMOSPHERE MODIFIEE AVEC REDUCTION ACCELEREE DU TAUX D’OXYGENE DANS LE COMPARTIMENT VIANDE

(84) Designated Contracting States: • GOULETTE, Stephen, L. AT BE CH DE DK ES FR GB GR IT LI LU NL PT SE Newark, NY 14513 (US) • HANSEN, Darryl, P. (30) Priority: 03.04.1998 US 54907 Shortsville, NY 14548 (US) • LUTHRA, Vinod, K. (43) Date of publication of application: Pittsford, NY 14534 (US) 31.01.2001 Bulletin 2001/05 • NORBY, Allen, J. Fairport, NY 14450 (US) (73) Proprietor: Pactiv Corporation • SLOAN, Robert, A. Lake Forest, IL 60045 (US) Palmyra, NY 14522 (US) • THOMPSON, Jill, F. (72) Inventors: Camp Hill, Pennsylvania 17011 (US) • CARR, Daniel, G. Lake Forest, Illinois 60045 (US) (74) Representative: Schuster, Thomas • CASTNER, Glenn, C. Grünecker, Kinkeldey, Stockmair & Victor, NY 14564 (US) Schwanhäusser • DELDUCA, Gary, R. Anwaltssozietät Canandaigua, NY 14424 (US) Maximilianstrasse 58 • DEMAY, Rollie, H. 80538 München (DE) Newark, NY 14513 (US) • DEYO, Alan, E. (56) References cited: Rushville, NY 14544 (US) EP-A- 0 457 457 US-A- 4 332 845 US-A- 4 579 223 US-A- 5 698 250

Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 071 619 B1

Printed by Jouve, 75001 PARIS (FR) 1 EP 1 071 619 B1 2

Description The tray 16 contains a retail cut of raw meat 26. An oxygen scavenger 28 is located between the inner con- FIELD OF THE INVENTION tainer 14 and the outer container 12. [0006] To create a modified atmosphere in the pack- [0001] The present invention relates generally to 5 age 10, DelDuca employs the following method. First, modified atmosphere packages for storing food such as the meat 26 is placed within the inner container 14, and raw meat. More particularly, the invention relates to a the inner container 14 is then sealed. Second, the inner modified atmosphere package having two compart- container 14 is inserted into the outer container 12. ments, one containing meat, separated by a substan- Third, without using any evacuation, the outer container tially permeable partition member, and relates to tech- 10 12 is flushed with an appropriate mixture of gases, such niques for rapidly reducing the oxygen level in the meat- as 30 percent carbon dioxide and 70 percent nitrogen, containing compartment below pigment sensitive levels to remove most of the oxygen from the outer container so that the growth of metmyoglobin is inhibited. 12. Fourth, the outer container 12 is sealed. Fifth, the oxygen scavenger 28 is activated and used to absorb BACKGROUND OF THE INVENTION 15 any residual oxygen within the package 10. The DelD- uca method relies upon activation of the oxygen scav- [0002] Containers have long been employed to store enger 28 to quickly absorb the residual oxygen. and transfer perishable food prior to presenting the food [0007] FIG. 2 identifies four oxygen sources, or at a market where it will be purchased by the consumer. zones, that exist within the package 10. Zone I is the After perishable foods, such as meats, fruits, and veg- 20 oxygen volume between the outer container 12 and the etables, are harvested, they are placed into containers inner container 14; zone II is the oxygen volume within to preserve those foods for as long as possible. Maxi- the inner container 14; zone III is the oxygen volume mizing the time in which the food remains preserved in within the cells of the foam tray 16; and zone IV is the the containers increases the profitability of all entities in oxygen volume within the meat 26, which is believed to the chain of distribution by minimizing the amount of 25 be minimal with the exception of ground meats. The ox- spoilage. ygen scavenger 28 is located in zone I. [0003] The environment around which the food is pre- [0008] In the above-described DelDuca method, the served is a critical factor in the preservation process. step of flushing the outer container 14 lowers the level Not only is maintaining an adequate temperature impor- of oxygen within the package 10 to about 0.05 to 5 per- tant, but the molecular and chemical content of the gas- 30 cent. At such oxygen levels, especially at the lower end es surrounding the food is significant as well. By provid- of the above range (0.05 to 2 percent), metmyoglobin ing an appropriate gas content to the environment sur- can form very quickly. Metmyoglobin is a substance that rounding the food, the food can be better preserved causes meat to change to an undesirable brown color. when maintained at the proper temperature or even Metmyoglobin forms very slowly at oxygen levels above when it is exposed to variations in temperature. This 35 2 percent and below 0.05 percent but very quickly be- gives the food producer some assurance that after the tween these oxygen levels, Accordingly, it is important food leaves his or her control, the food will be in an ac- to pass the meat located in zone II through the pigment ceptable condition when it reaches the consumer. sensitive oxygen range (0.05 to 2 percent) very quickly [0004] Modified atmosphere packaging systems for e.g. less than about two hours. Although DelDuca con- one type of food, raw meats, exposes these raw meats 40 templates flushing the inner container 14, existing tech- to either extremely high levels or extremely low levels nology generally will not flush zone II down below the of oxygen (O2). Packaging systems which provide ex- pigment sensitive oxygen range. Therefore, even if the tremely low levels of oxygen are generally preferable inner container 14 is flushed, the oxygen level in zone because it is well known that the fresh quality of meat II must still be passed quickly through the pigment sen- can be preserved longer under anaerobic conditions 45 sitive oxygen range. than under aerobic conditions. Maintaining low levels of [0009] In DelDuca, after the outer container 12 is oxygen minimizes the growth and multiplication of aer- sealed, oxygen remaining in zone II(within the inner con- obic bacteria tainer 14) passes trough the substantially, but not 100 [0005] One example of a low-level oxygen system is percent, permeable material of the inner container 14 disclosed in U.S. Patent No. 5,698,250 to DelDuca et 50 and is rapidly absorbed by the activated oxygen scav- al. ("DelDuca"). FIGS. 1 and 2 of DelDuca are repro- enger 28 in zone I. The faster the rate of oxygen egress duced herein as FIGS. 1 and 2. Referring to FIGS. 1 and from zone II into zone I, the faster the oxygen level in 2, DelDuca discloses a modified atmosphere package zone II can be passed quickly through the pigment sen- 10 including an outer container 12 composed of a oxy- titive oxygen range. The present invention is directed to gen barrier material and an inner container 14 com- 55 technique for improving the rate of oxygen egress from posed of a material substantially permeable to oxygen. zone II into zone I. In addition, the present invention is The inner container 14 is preferably comprised of a pol- directed to techniques for directly absorbing oxygen in ystyrene foam tray 16 and a stretch film wrapping 18. zone II before the oxygen passes into zone I.

2 3 EP 1 071 619 B1 4

[0010] In the state of the art, for exmple in the Euro- both the stretch film wrapping and through the exposed pean patent application EP 0 457 457 A2 an oxygen ab- section of the tray wall. sorbant is revealed. This oxygen absorbent which is [0015] Other techniques for rapidly reducing the oxy- used scaled in a pack with food to prevent the food from gen level in the second compartment pertain less to deteriorating is disclosed, in which the oxygen absorb- 5 changing the structure of the partition member. For ex- ent contains ascorbic acid and/or salts thereof, an alka- ample, a second oxygen scavenger can be placed in- lins compound such as sodium carbonate, a reaction side the second compartment away from the meat, or accelerator such as fermous sulphate and a silica gel scavenging material can be dispersed in the tray wall. and improves the flowability and the oxygen absorbabil- Alternatively, carbon dioxide pellets can be placed in- ity. In this European patent application it is not revealed 10 side the second compartment away from the meat. The how an oxygen absorbent should be disposed in a pack pellets serve as a flushing agent that forces oxygen out sealing a food product. Therefore a new solution for of the second compartment. Also, the finished package packing a food product together with an drygen absorb- can be irradiated to create ozone (O3) within the pack- ant has to be found. age. Ozone is more readily scavenged by the oxygen [0011] The invention is defined of the features of claim 15 scavenger. 1. [0012] In accordance with an embodiment a modified BRIEF DESCRIPTION OF THE DRAWINGS atmosphere package includes first and second compartments separated by a partition member that is sub- [0016] Other objects and advantages of the invention stantially permeable to oxygen. The first compartment 20 will become apparent upon reading the following de- contains an oxygen scavenger activated with an oxygen tailed description and upon reference to the drawings in scavenger accelerator. The second compartment con- which: tains a retail cut of raw meat. [0013] To improve the flow of any oxygen in the sec- FIG. 1 is an isometric view of a modified atmos- ond compartment from the second compartment to the 25 phere package not being part of the invention but first compartment, one or more features can be incor- being important for the understanding of the inven- porated in the partition member to improve its permea- tion; bility. For example, if the partition member is partially comprised of a stretch film wrapping such as polyvinyl FIG. 2 is a section view taken generally along line chloride (PVC), the stretch film wrapping can be provid- 30 2-2 in FIG. 1; FIG. 3 is an enlarged view taken gen- ed with a plurality of holes in the form of relatively large erally along circled portion 3 in FIG. 2; holes, pin holes, or microperforations. If the holes are relatively large holes, e.g., having a diameter ranging FIG. 4 is a diagrammatic side view of a system for from about 0,3175 cm to about 1.905 cm, the holes ate making the modified atmosphere package; preferably covered with a label composed of TYVEK® 35 spunbonded olefin or paper to prevent meat juice from FIG. 5a is a top view of a section of the modified leaking out of the second compartment through the atmosphere package with a portion of the outer holes and to prevent desiccation and contamination of package broken away to reveal an inner package the meat. The label is adhered to the stretch film wrap- having stretch film wrapping with a hole covered by ping in areas around the holes. TYVEK spunbonded ole- 40 a TYVEK patch; fin is entirely permeable to oxygen, so no additional holes are formed in the TYVEK label. If, however, the FIG. 5b is an enlarged section view taken generally label is composed of paper or plastic, which are some- along line 5b--5b in FIG. 5a; what impermeable to oxygen, pin holes or microperforations are formed in the label. 45 FIG. 6a is a top view of the modified atmosphere [0014] Various other features can be incorporated in package with a portion of outer package broken the partition member to increase its permeability, includ- away to reveal an inner package having perforated ing a snorkel or straw; embossments; a self-sealing film stretch film wrapping, not being part of the invention or coating to allow for the creation of temporary holes in but being important for the understanding; the partition member; a Landec-type film having a per- 50 meability that can be controlled by heat, light, or some FIG. 6b is an enlarged section view taken generally other energy source; and two layers of perforated along line 6b-6b in FIG. 6a; stretch film wrapping. If the partition member includes a stretch film wrapping wrapped about a foam tray, a sec- FIG. 6c is an enlarged view similar to FIG. 3 but tion of the tray wall can be composed of open-cell or 55 showing pin holes formed in a tray wall, not being perforated foam. This section of the tray wall is left un- part of the invention, but being important for the un- covered by the stretch film wrapping to allow oxygen derstanding; from the second compartment to readily pass through

3 5 EP 1 071 619 B1 6

FIG. 7a is a top view of a section of the modified package 12 and an inner package 14. The term "pack- atmosphere package with a portion of the outer age" as used herein shall be defined as any means for package broken away to reveal an inner package holding raw meat, including a container, carton, casing, having stretch film wrapping with a hole covered by parcel, holder, tray, flat, bag, film envelope, etc. At least a perforated paper or plastic patch; 5 a portion of the inner package 14 is permeable to oxygen. The inner package 14 includes a conventional FIG. 7b is an enlarged section view taken generally semi-rigid plastic tray 16 thermoformed from a sheet of along line 7b-7b in FIG. 7a; polymeric material which is substantially permeable to oxygen. Exemplary polymers which may be used to FIG. 8 is an enlarged view similar to FIG. 3 but 10 form the non-barrier tray 16 include polystyrene foam, showing an inner package having stretch film wrap- cellulose pulp, polyethylene, polypropylene, etc. In an ping comprised of two layers of perforated film; embodiment, the polymeric sheet used to form the tray 16 is substantially composed of polystyrene foam and FIG. 9 is an enlarged view similar to FIG. 3 but has a thickness ranging from about 0,00254 meters to showing a straw mounted to the inner package of 15 about 0,00762 meters. The use of a common polysty- the modified atmosphere package; rene foam tray 16 is desirable became it has a high consumer accepetance. The inner package 14 further in- FIG. 10 is an enlarged view similar to FIG. 3 but cludes a stretch film wraping or cover 18 substinatially showing an inner package having an embossed composed of a Polymeric material, such as polyvinylly stretch film wrapping, not being part of the invention 20 chloride (PVC), which is substantially permeable to ox- but being important for the understanding; ygen. Like a form tray, a PVC stretch film wrapping has a high consumer acceptance. In an embodiment, the FIG. 11a is an enlarged side view similar to FIG. 3 stretch film used to form the cover 18 contains additives but showing holes punched through an inner pack- which allow the film to cling to itself a thickeness ranging age wrapping comprised of standard stretch film 25 from about 1,269x 10-5 meters to about 3.81 x 10-5 me- coated with a self-sealing layer of low molecular ters, and has a rate of oxygene permeability greater than weight wax or polymer. about 1000 cubic centimeters per 645 square centimeters in 24 hours. Preferably, the film fas a rate of oxygen FIG. 11b is an enlarged side view similar to FIG. 1a permeability greater than about 7,000 cubic centimeters but showing the holes plugged by the self-sealing 30 per 645 square centimeters in 24 hours and, most pref- layer, erably, has a rate of oxygen permeability greater than about 10,000 cubic centimeters per 645 square centim- FIG. 12 is an enlarged side view similar to FIG. 3 eters in 24 hours. One preferred stretch film is Resin- but showing an unwrapped section of the tray wall ite™ meat film commercially available from Borden formed from open cell or perforated foam, not being 35 Packaging and Industrial Products of North Andover, part of the invention but being important for the un- Massachusetts. derstanding; [0018] The tray 16 is generally rectangular in configuration and includes a bottom wall 20, a continuous side FIG. 13 is an enlarged side view similar to FIG. 3 wall 22, and a continuous rim or flange 24. The contin- but showing an oxygen scavenging packet affixed 40 uous side wall 22. encompasses the bottom wall 20 and to the tray wall and oxygen scavenging material dis- extends upwardly and outwardly from the bottom wall persed within the tray wall; 20. The continuous rim 24 encompasses an upper edge of the continuous side wall 22 and projects laterally out- FIG. 14 is an enlarged side view similar to FIG. 3 wardly therefrom. A food item as a retail cut of raw meat but showing carbon dioxide pellets along the tray 45 26 is located in a rectangular compartment defined by wall, not being part of the invention but being impor- the bottom wall 20 and continuous side wall 22. The raw tant for the understanding: and meat may be any animal protein, including beef, pork, veal, lamb, chicken, turkey, venison, fish, etc. Prior to FIG. 15 is a top view of a section of the modified fully wrapping the tray 16 with the cover 18, the partially atmosphere package with a portion of outer pack- 50 formed inner package 14 may be flushed with an appro- age broken away to reveal an inner package having priate mixture of gases, typically a mixture of about 30 stretch film wrapping with a hole covered by a Lan- percent carbon dioxide and about 70 percent nitrogen, dec-type film patch. to lower the oxygen leved in the inner package 14 to about 1.5 to 5.0 percent. The foregoing mixture of gases DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 55 displaces the oxygen within the inner package 14 during the flushing operation. After flushing the inner package [0017] Turning now to the drawings, FIGS. 1-3 depict 14, the tray 16 is manually or automatically wrapped with a modified atmosphere package 10 including an outer the cover 18. The cover is wrapped over the retail cut of

4 7 EP 1 071 619 B1 8 raw meat 26 and about both the side wall 26 and bottonn solutions of acetic acid, citric acid, sodium chloride, cal- wall 20 of the tray 16. The free ends of the cover 18 are cium chloride, magnesium chloride and copper. overlapped along the underside of the bottom wall 20 of [0021] Further information concerning the oxygen the tray 16, and, due to the cling characteristic inherent scavenger 28, the oxygen uptake accelerator, and the in the cover 18, these overlapping free ends cling to one 5 means for introducing the oxygen uptake accelerator to another to hold the cover 18 in place. If desired, the over- the oxygen scavenger 28 may be obtained from appli- wrapped tray 16, i.e., the inner package 14, may be run cation serial no. 08/856,448, filed May 14, 1997, entitled over a hot plate to thermally fuse the free ends of the 5 "Oxygen Scavenger Accelerator," and incorporated cover 18 to one another and thereby prevent these free herein by reference. In FIGS. 1-3, the oxygen scavenger ends from potentially unraveling. 10 28 is illustrated as a packet or label which is inserted [0019] The outer package 12 is preferably a flexible into the bag 12 prior to sealing the bag 12. Alternatively, polymeric bag composed of a single or multilayer plas- an oxygen scavenging material may be added to the pol- tics material which is substantially impermeable to oxy- ymer or polymers used to form the outer package 12 so gen. The polymeric bag 12 may, for example, include a that the oxygen scavenging material is integrated into multilayer coextruded film containing ethylene vinyl 15 the outer package 12 itself. chloride (EVOH), or include an oriented polypropylene [0022] The retail cut of raw meat 26 within the modi- (OPP) core coated with an oxygen barrier coating such fied atmosphere package 10 takes on a purple-red color as polyvinylidene chloride and further laminated with a when the oxygen is removed from the interior of the layer of sealant material such as polyethylene in facili- package 10. The meat-filled modified atmosphere pack- tate heat sealing. In a different embodiment, the poly- 20 age 10 may now stored in a refrigeration unit for several meric bas 12 is composed of a coextruded barrier film weeks prior to being offered for sale at a grocery store. commercially available as product no. 32SC44-EX861B A short time (e.g., less than one hour) prior to being dis- from PrintPack Inc. of Atlanta, Georgia. The coextruded played at the grocery store, the inner package 14 is re- barrier film has a thickness ranging from about 2,538 x moved from the polymeric bag 12 to allow oxygen from 10-5 meters to about 7,614 x 10-5meters and has a rate 25 the ambient environment to permeate the non-barrier of oxygen permeability less than about 0.1 cubic cen- tray 16 and non-barrier cover 18. The purple-red color timeters per 645 square centimeters in 24 hours. Prior of the raw meat 26 quickly changes or "blooms" to a gen- to sealing the peripheral edges of the polymeric bag 12, erally acceptable bright red color when the raw meat 26 the inner package 14 is placed within the polymeric bag is oxygenated by exposure to air. 12. Also, the bag 12 is flushed with an appropriate mix- 30 [0023] FIG. 4 illustrates a modified atmosphere pack- ture of gases, typically about 30 percent carbon dioxide aging system used to produce the modified atmosphere and about 70 percent nitrogen, to lower the oxygen level package 10 in FIGS. 1-3. The packaging system inte- in the bag 12 to about 0.05 to 5.0 percent. After flushing grates several disparate and commercially available the bag 12, but still prior to sealing the bag 12, an oxygen technologies to provide a modified atmosphere for retail scavenger/absorber 28 is placed in the bag 12 external 35 cuts of raw meat. The basic operations performed by to the sealed inner package 14. The bag 12 is than the packaging system are described below in connec- sealed. tion with FIG. 4. [0020] The oxygen scavenger 28 is designed to re- [0024] The packaging process begins at a thermofor- duce the oxygen level in the bag 12 at a rate sufficient ming station 30 where a tray 16 is thermoformed in con- to prevent discoloration (e.g, browning) of the raw meat 40 ventional fashion from a sheet of polystyrene or other 26. Many factors influence the color stability of raw non-barrier polymer using conventional thermoforming meat, but it has been found that the reduction of the ox- equipment. The thermoforming equipment typically in- ygen level from the 0.05 to 5.0 percent level described cludes a male die member 30a and a female die cavity about 10 less than about 0.05 percent within 90 minutes 30b. As is well known in the thermoforming art, the tray works for all types of raw meat. If there is still oxygen in 45 16 is thermoformed by inserting the male die member the bag 12 after this time period, the oxygen scavenger 30a into the female die cavity 30b with the polymeric 28 absorbs any remaining oxygen in the bag 12 and any sheet disposed therebetween. oxygen which might still be trapped within the inner con- [0025] The thermoformed tray 16 proceeds to a goods tainer 14 so as to lower the oxygen level in the bag 12 loading station 32 where the tray 16 is filled with a food to about zero percent within 24 hours. The oxygen scav- 50 product such as a retail cut of raw meat 26. The meat- enger 28 also absorbs any oxygen which might perme- filled tray 16 is then manually carried or transported on ate into the bag 12 from the ambient environment. To a conveyor 34 to a conventional stretch wrapping station increase the rate of oxygen absorption, the oxygen 36 where a stretch film 18 is wrapped about the tray 16 scavenger is activated with an oxygen uptake acceler- to enclose the retail cut of meat 26 therein. The over- ator in the form of a predetermined amount of activating 55 wrapped tray 16 forms the inner package 14. Just prior agent or by other means just prior to being placed in the to sealing the meat-filled tray 16 at the stretch wrapping bag 12. The oxygen uptake accelerator is preferably se- station 36, the tray 16 is flushed with a mixture of carbon lected from the group consisting of water or aqueous dioxide and nitrogen to reduce the oxygen level in the

5 9 EP 1 071 619 B1 10 tray 16 to about 1.5 to 5.0 percent. The mixture of carbon falo, New York. dioxide and nitrogen emanates from a conventional gas [0029] The modified atmosphere packaging system in supply hollow tube or rod 40 fed by a gas tank (not FIG. 4 can produce the modified atmosphere packages shown). The stretch wrapping station 36 may be imple- 10 at cycle rates ranging from about 1 to 60 packages mented with a compact stretch semi-automatic wrapper 5 per minute. The maximum cycle rates which can be at- commercially available from Hobart Corporation of Troy, tained by the system in FIG. 4 are significantly higher Ohio. than the cycle rates which can be achieved by prior art [0026] Next, the flushed and sealed inner package 14 systems. The attainment of high cycle rates is largely proceeds to a high speed form, fill, and seal station 42 due to the fact that the packaging system in FIG. 4 relies which may be implemented with a Fuji-Formost high- 10 upon the use of simple, commercially available, and speed horizontal form-fill-seal machine commercially high-speed form, fill, and seal equipment, as opposed available as model no. FW-3700 from Formost Packag- to the slower evacuation equipment employed by prior ing Machines, Inc. of Woodinville, Washington. The in- art systems. Reducing oxygen levels in the modified at- ner package 14 may be transported to the form, fill, and mosphere package 10 by first flushing the package 10 seal station 42 by a conveyor 44. At the form, fill, and 15 and then subsequently introducing the activated oxygen seal station 42, a web 46 of oxygen barrier film from a scavenger 28 into the package 10 is significantly faster roll 47 is arranged to run along the direction of move- and more cost-effective than the reliance upon slow ment of the inner package 14. The web 46 of film is fed evacuation techniques. to a conventional forming box which forms a section 48 [0030] Referring to FIG. 2, the region outside the inner of the web 46 into a tube configuration encompassing 20 package 14 and inside the outer package 12 defines a the inner package 14. The tube-shaped section 48 of first compartment or zone I, while the region inside the the web 46 is thermally sealed along a lower fin 50 and inner package 14 defines a second compartment or is thermally sealed at one end 52 by a pair of vertically- zone II. The inner package 14 itself forms a partition oscillating heated sealing bars 54 or the like. member between the first and second compartments. [0027] Just prior to sealing the other end 56 of the 25 As 5 discussed above, after the outer package 12 is tube-shaped web section 48 to complete formation of sealed during the manufacturing process, it is desirable the polymeric bag 12, the web section 48 is flushed with to improve the flow of oxygen from the second compart- an appropriate mixture of gases, typically about 30 per- ment to the first compartment so that any oxygen in the cent carbon dioxide and about 70 percent nitrogen, to second compartment can be rapidly absorbed by the ac- lower the oxygen level in the bag 12 to about 0.05 to 5.0 30 tivated oxygen scavenger 28 in the first compartment. percent. The mixture of carbon dioxide and nitrogen em- The improved flow of oxygen, in turn, minimizes the anates from a conventional gas supply hollow tube or amount of time that the meat in the second compartment rod 58 fed by a gas tank (not shown). After flushing the is exposed to oxygen levels in the pigment sensitive web section 48, but still prior to sealing the end 56, the range (0.05 to 2 percent). Minimizing the exposure of oxygen scavenger/absorber 28 is placed in the web sec- 35 the meat to oxygen levels in the pigment sensitive range tion 48 external to the sealed inner container 14 and the inhibits the formation of metmyoglobin, which can cause oxygen scavenger 28 is activated with an oxygen uptake the meat to change to an undesirable brown color. accelerator. The end 56 is then conveyed between and [0031] The present invention provides various fea- sealed by the heated sealing bars 54 to complete for- tures that can be incorporated in the inner package 14 mation of the bag 12. In addition to thermally fusing the 40 to increase its oxygen permeability to rates in excess of web section 48 at the end 56, the heated sealing bars about 7,000 cubic centimeters per 645 square centim- 54 sever the web section 48 at the end 56 to separate eters in 24 hours and, most preferably, to rates in excess the bag 12 from the next upstream web section being of about 10,000 cubic centimeters per 645 square cen- formed into another bag. The sealed bag 12 is substan- timeters in 24 hours. Such high rates of oxygen perme- tially in the form of a sealed bubble or envelope loosely 45 ability allow the activated oxygen scavenger 28 in the containing the inner package 14 and providing a sealed first compartment to lower the oxygen level in the sec- modified atmosphere surrounding the inner package 14. ond compartment (inner package 14) to less than about [0028] The oxygen scavenger 28 lowers the oxygen 0.05 percent within a time period of less than about two level in the package 10 from the previously described hours and typically about 90 minutes after the package 0.05 to 5.0 percent oxygen level to less than about 0.05 50 10 is sealed. The permeability-increasing features can percent within a time period of about 90 minutes. Al- be employed separately or in combination. In addition though the oxygen scavenger 28 is depicted in FIG. 4 to increasing the oxygen permeability of the inner pack- as a packet or label inserted into the polymeric bag 12, age 14, the present invention addresses other concerns an oxygen scavenger may alternatively be integrated in- such as preventing meat juices (purge) from escaping to the polymers used to form the bag 12. One preferred 55 the inner package 14, preventing desiccation of the oxygen scavenger is a FreshPax™ oxygen absorbing meat, and preventing bacterial contamination of the packet commercially available from MultiSorb Technol- meat. Leakage of juices from the inner package is a sig- ogies, Inc. (formerly Multiform Desiccants Inc.) of Buf- nificant drawback of the system proposed by U.S. Pat-

6 11 EP 1 071 619 B1 12 ent No. 5,667,827 to Breen et al. applied to most of the portion of the wrapping 18 located [0032] Referring to FIGS. 5a-b, 6a-b, and 7a-b, if the inside the tray side wall 22 and are arranged in a rec- inner package 14 is partially comprised of a stretch film tangular grid. Adjacent ones of the holes are spaced ap- wrapping 18 such as polyvinyl chloride (PVC), the proximately one inch from each other. Alternatively, as stretch film wrapping 18 can be provided with one or 5 shown in FIG. 6c, pin holes 64 can be formed in an un- more relatively large holes 60 (FIGS. 5a-b and 7a-b) or wrapped section of the side wall 22 of the tray 16. As a plurality of pin holes or microperforations 62 (FIGS. shown in FIG. 8, if larger perorations are desired, the 6a-b). The holes 62 in FIG. 6a can represent either pin stretch film wrapping 18b may be comprised of two per- holes or microperforations. In order for the holes to be forated layers in which the perforations 62a of one layer elective, they must communicate with the interior of the 10 are offset from (not aligned with) the perforations 62b of package 14. Accordingly, the holes should be located the other layer. The offset perforations create a tortuous along the portion of the stretch film wrapping 18 gener- path that prevents leakage of meat juices from the inner ally above the tray bottom wall 20 and inside the contin- package 14. uous tray side wall 22. The holes may be made during [0035] Experiments have found that all of the above the manufacture of the stretch film wrapping 18 or just 15 options concerning the application of holes and labels prior to covering the tray 16 with the wrapping 18. to the stretch film wrapping 18 successfully increase the [0033] If the holes are relatively large holes 60 as in oxygen permeability of the inner package 14 to rates FIGS. 5a-b and 7a-b, e.g., having a diameter ranging that allow the activated oxygen scavenger 28 in the first from about 0,00318 meters to about 0,01905 meters, compartment to lower the oxygen level in the second the holes are preferably covered with a patch or label 20 compartment (inner package 14) to less than about 0.05 66 composed of TYVEK® spunbonded olefin, paper, or percent within a time period of less than about two hours plastic to prevent meat juice from leaking out of the sec- after the package 10 is sealed. Specifically, the experi- ond compartment through the holes and to prevent des- ments tested the following options: one hole having a iccation and contamination of the meat. TYVEK spun- diameter of 3,18 x 10-3 meters, one 6,35 x 10-3 meter bonded olefin is commercially available from DuPont of 25 hole, one 3,18 x 10-3 hole, four 3,18 x 10-3 meter holes Wilmington, Delaware. The holes are punched in the with TYVEK label, one 6,35 x 10-3 meter hole with TY- stretch film wrapping 18 before the label 66 is applied. VEK label, one 3,18 x 10-3 meter hole with TYVEK label, The label 66 could be decorative or could provide pricing one 0,01905 meter hole with TYVEK label, one 0,01905 information. Using a food-grade adhesive, the label 66 meter hole with paper label having 15 pin holes, one is adhered to the stretch film wrapping 18 in areas 30 0,01905 meter hole with paper label having 12 pin holes, around the holes. In one embodiment best shown in 6 pin holes, 12 pin holes, and microperforations through- FIG. 5b, the label 66 is circular, has an outer diameter out the stretch film wrapping. Each of the above options of 0,01905 meters, and has adhesive applied to an ares helped the stretch film wrapping attain acceptable high bound by the outer diameter of 0,01905 meters and an rates of oxygen permeability. inner diameter of about 0,00953 to 0,0127 meters. The 35 [0036] Various other features can be incorporated in area within the inner diameter is free of adhesive. With the partition member to increase its permeability. FIG 9 respect to a TYVEK label (FIGS. 5a-b), since TYVEK depicts a snorkel or straw 72 inserted through the spunbonded olefin is entirely permeable to oxygen, no stretch film wrapping 18 and the side wall 22 of the tray additional holes are formed in the TYVEK label. When 16 and into the interior of the tray. FIG. 10 depicts alter- attaching the TYVBK label to the stretch turn wrapping, 40 natives not being part of the invention but being impor- the food-grade adhesive is not applied to the portion of tant for the understanding, such as embossments 74 the label covering the holes so that the oxygen perme- formed in the stretch film wrapping 18. The embossed able pores in the label are not plugged by the adhesive. areas of the stretch film wrapping are thinner than other With respect to a paper or plastic label (FIGS. 7a-b), areas of the stretch film wrapping and, therefore, exhibit which is somewhat impermeable to oxygen, additional 45 higher oxygen permeability rates. FIGS. 11a and 11b de- pin holes or microperforations 70 (FIG. 7b) are formed pict a stretch film wrapping 18a including a PVC layer in the label. Although a label 66 over the relatively large 67 and a thin self-sealing layer 68 of food-grade wax or holes in the stretch film wrapping 18 is preferred, the polymer having a low molecular weight. The self-sealing label is not absolutely necessary so long as care is taken layer 68 can be applied to the PVC layer 67 by conven- to avoid tilting the package 10 to a degree that allows 50 tional spraying techniques or by conventional applica- meat juices to leak out of the inner package 14. tion and metering rollers of a printing press. Since the [0034] If, on the other hand, the holes are pin holes layer 68 is self-sealing, holes 76 formed in the wrapping or microperforations 62 (FIG. 6a) having a diameter 18a are only temporary and are plugged by the self-seal- ranging from about 1 x 10-4 meters to about 7,6 x 10-4 ing layer 68 over time (FIG. 11b). The holes 76 are meters, a label is not preferred because the holes are 55 formed in the wrapping 18a during the manufacturing sufficiently small in diameter that surface tension pre- process prior to sealing the package 10 and are ex- vents meat juice from passing through the holes. In the posed long enough to allow the oxygen scavenger 28 illustrated different embodiment, the small holes 62 are to lower the oxygen level in the inner package 14 to less

7 13 EP 1 071 619 B1 14 than about 0.05 percent in less than about two hours sorbs any oxygen present in the second compartment after the package 10 is sealed. As shown in FIG. 11b, (inner package 14) and does not require the oxygen to the holes 76 are preferably plugged prior to shipping the pass from the second compartment to the first compart- meat-filled package 10 to eliminate the possibility of ment in order to be absorbed. leakage of meat juices from the inner package 14. 5 [0040] Alternatively, as shown in FIG. 14, not being [0037] In another embodiment, not being part of the part of the invention but being important for the under- invention but being important for the understanding, the standing, carbon dioxide pellets 80 (dry ice) can be stretch film wrapping 18 in FIGS. 1-3 is composed of a placed inside the inner package 14 away from the meat Landec-type film, produced by the so-called Intellimer 26. The pellets 80 serve as a flushing agent that forces process, having a permeability that can be controlled by 10 oxygen out of the inner package 14 even after the pack- heat, light, or some other energy source. The film is nor- age 10 is sealed. In yet another embodiment, the sealed mally in a substantially impermeable amorphous state package 10 is irradiated to create ozone (O3) within the and can be temporarily switched to a highly permeable package 10. Ozone is more readily scavenged than ox- crystalline state by application of the energy source. The ygen (O2) by the oxygen scavenger 28, and therefore energy source is applied to the Landec-type film during 15 oxygen levels within the second compartment (inner the manufacturing process and for a long enough time package 14) holding the meat 26 are reduced more rap- period after the package 10 is sealed to allow the oxygen idly. In effect, the carbon dioxide pellets 80 and the cre- scavenger 28 to lower the oxygen level in the second ation of ozone each increase the rate of oxygen egress compartment (inner package 14) to less than about 0.05 from the second compartment (inner package 14) to the percent in less than about two hours. Alternatively, as 20 first compartment. depicted in FIG. 15, the stretch film wrapping 18 can be composed of conventional polyvinyl chloride and include a hole 73 covered by a label 75 composed of a Claims Landec-type film. [0038] In yet another embodiment, not being part of 25 1. A modified atmosphere package (10) comprising: the invention but being important for the understanding, depicted in FIG. 12, the inner package 14 includes a first (12) and second compartments (14) sepa- stretch film wrapping 18 wrapped partially about a foam rated by a partition member substantially per- tray 16a having an exposed (unwrapped) section 77 meable to oxygen, said first compartment (12) composed of open-cell or perforated polystyrene foam. 30 containing an oxygen scavenger (28) activated The open-cell or perforated foam section 77 of the tray with an oxygen scavenger (28) accelerator, 16a is highly permeable to oxygen and helps the inner said second compartment (14) containing a re- package 14 to attain a higher rate of oxygen permeabil- tail cut of raw meat (26), said partition member ity than an inner package composed entirely of a close- including a tray (16) covered by a stretch film cell foam. To take advantage of the highly permeable 35 (18) wrapping, said tray (16) and said stretch open-cell or perforated foam section 77 of the tray 16a, film (18) wrapping enclosing said second com- the coverage of the stretch film wrapping 18 on the tray partment (14); said tray (16) having a bottom bottom is partial to allow oxygen from the inner package wall and a continuous sidewall extending up- 14 to pass through the open-cell or perforated foam sec- wardly from said bottom wall, and permeability tion. 40 enhancement means for increasing a permea- [0039] Other possible techniques for rapidly reducing bility rate of said partition member to a rate in the oxygen level in the second compartment (inner excess of about 7,000 cubic centimetres per package 14) pertain less to altering the structure of the 0,064516 m2 (100 square inches) in 24 hours tray 16 or the stretch film wrapping 18. For example, as so that formation of metmyoglobin in said raw shown in FIG. 13, not being part of the invention but be- 45 meat (26) is inhibited characterised in that ing important for the understanding, a second oxygen said stretch film (18) wrapping including said scavenger 78 can be placed inside the inner package permeability enhancement means, said perme- 14 away from the meat 26. Alternatively or in addition, ability enhancement means including perfora- oxygen scavenging material 79 can be dispersed in the tions (62; 76) formed in said stretch film (18) wall of the tray 16. Like the oxygen scavenger 28, the 50 wrapping interior to said sidewall. oxygen scavenger 78 is preferably activated with an oxygen scavenger accelerator just prior to sealing the in- 2. The package (10) of Claim 1, wherein said perfora- ner package 14 during the manufacturing process. To tions (62) have a diameter ranging from about keep the oxygen scavenger 78 separated from the meat 0,1016 mm (0.004 inch) to about 0,762 mm (0.030 26, the oxygen scavenger 78 can be adhered by a food- 55 inch) so that surface tension prevents juices from grade adhesive to one side of the tray 16 or can be said meat from leaking through said perforations housed in a highly permeable enclosure along one side (62). of the tray 16. The oxygen scavenger 78 directly ab-

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3. The package (10) of Claim 1 or 2, wherein said 2. Verpackung (10) nach Anspruch 1, wobei die Per- stretch film (18) wrapping includes first (67) and forationen (62) einen Durchmesser zwischen unge- second (68) layers of film each containing said per- fähr 0,1016 mm (0,004 Inch) und ungefähr 0,762 forations (62), said perforations in said first layer be- mm (0,030 Inch) haben, so dass Oberflächenspan- ing offset from said perforations (62) in said second 5 nung verhindert, dass Säfte aus dem Fleisch durch layer to create a tortuous path that prevents juices die Perforationen (62) hindurchtreten. from said meat from passing through said stretch film (18) wrapping. 3. Verpackung (10) nach Anspruch 1 oder 2, wobei die Dehnfolienverpackung (18) eine erste (67) und eine 4. The package (10) of one of the Claims 1 to 3, where- 10 zweite (68) Schicht aus Folie enthält, die jeweils die in said stretch film (18) wrapping includes a stretch Perforationen (62) enthalten, und die Perforationen film (18) layer and a self-sealing layer (68) each be- in der ersten Schicht gegenüber den Perforationen ing substantially permeable to oxygen, said perfo- (62) in der zweiten Schicht versetzt sind, um einen rations (62) initially passing through said stretch film gewundenen Weg zu erzeugen, der verhindert, (18) layer and said self-sealing layer and subse- 15 dass Säfte aus dem Fleisch durch die Dehnfolien- quently being plugged by said self-sealing layer verpackung (18) hindurchtreten. (68). 4. Verpackung (10) nach einem der Ansprüche 1 bis 5. The package (10) of one of the Claims 1 to 4 where- 3, wobei die Dehnfolienverpackung eine Dehnfoli- in said stretch film (18) layer is comprised of poly- 20 enschicht (18) und eine selbstdichtende Schicht vinyl chloride and said self-sealing layer is com- (68) enthält, die jeweils im Wesentlichen durchläs- posed of a low molecular weight wax or polymer. sig für Sauerstoff sind, wobei die Perforationen (62) anfänglich durch die Dehnfolienschicht (18) und die selbstdichtende Schicht hindurchtreten und an- Patentansprüche 25 schließend durch die selbstdichtende Schicht (68) verschlossen werden. 1. Verpackung (10) mit modifizierter Atmosphäre, die umfasst: 5. Verpackung (10) nach einem der Ansprüche 1 bis 4, wobei die Dehnfolienschicht (18) aus Polyvinyl- eine erste (12) und eine zweite (14) Kammer, 30 chlorid besteht und die selbstdichtende Schicht aus die durch ein Trennwandelement getrennt sind, einem Wachs oder Polymer mit niedrigem Moleku- das im Wesentlichen durchlässig für Sauerstoff largewicht zusammengesetzt ist. ist, wobei die erste Kammer (12) einen Sauer- stoff-Scavenger (28) enthält, der mit einem Be- schleuniger des Sauerstoff-Scavengers (28) 35 Revendications aktiviert wird, die zweite Kammer (14) eine Ein- zelhandels-Portion rohes Fleisch (26) enthält, 1. Conditionnement sous atmosphère modifiée (10) das Trennwandelement eine Schale (16) ent- comprenant : hält, die mit einer Dehnfolienverpakkung (18) abgedeckt ist, die Schale (16) sowie die Dehn- 40 un premier compartiment (12) et un second folienverpackung (18) die zweite Kammer (14) compartiment (14) séparés par un élément de umschließen, die Schale (16) eine Bodenwand séparation sensiblement perméable à l'oxygè- sowie eine durchgehende Seitenwand auf- ne, ledit premier compartiment (12) contenant weist, die sich von der Bodenwand aus er- un éliminateur d'oxygène (28) activé par un ac- streckt, und eine Permeabilitäts-Verbesse- 45 célérateur d'éliminateur d'oxygène (28), ledit rungseinrichtung, die eine Durchlässigkeitsrate second compartiment (14) contenant un mor- des Trennwandelementes auf eine Rate von ceau de viande crue (26) vendu au détail, ledit mehr als 7,000 cm3 pro 0,064516 m2 (100 élément de séparation incluant une barquette square inches) in 24 Stunden erhöht, so dass (16) couvert par un emballage de film extensi- die Entstehung von Metmyoglobin in dem ro- 50 ble (18), ladite barquette (16) et ledit emballage hen Fleisch (26) gehemmt wird, dadurch ge- de film extensible (18) entourant ledit second kennzeichnet, dass die Dehnfolienverpak- compartiment (14) ; ladite barquette (16) ayant kung (18) die Permeabilitäts-Verbesserungs- une paroi inférieure et une paroi latérale conti- einrichtung enthält und die Permeabilitäts-Ver- nue s'étendant vers le haut à partir de ladite pa- besserungseinrichtung Perforationen (62; 76) 55 roi inférieure, et des moyens d'amélioration de enthält, die in der Dehnfolienverpackung (18) la perméabilité permettant de faire augmenter innerhalb der Seitenwand ausgebildet sind. le taux de perméabilité dudit élément de sépa- ration pour atteindre un taux en excès d'environ

9 17 EP 1 071 619 B1 18

7,000 centimètres cubes par 0,064516 m2 (100 pouces carrés) en 24 heures, de telle sorte que la formation de métmyoglobine dans ladite viande crue (26) est neutralisée, caractérisé en ce que ledit emballage de film extensible 5 (18) inclut ledit moyen d'amélioration de per- méabilité, ledit moyen d'amélioration de per- méabilité incluant des perforations (62, 76) for- mées dans ledit emballage de film extensible (18) interne à ladite paroi. 10

2. Conditionnement (10) selon la revendication 1, dans lequel lesdites perforations (62) ont un diamè- tre compris entre 0,1016 mm (0,004 pouce) et 0,762 mm (0,030 pouce), de telle sorte la tension de sur- 15 face empêche le jus de ladite viande de fuir à travers lesdites perforations (62).

3. Conditionnement (10) selon la revendication 1 ou 2, dans lequel ledit emballage de film extensible 20 (18) inclut une première couche (67) et une seconde couche (68) de film, chacune contenant lesdites perforations (62), lesdites perforations dans ladite première couche étant en décalage par rapport auxdites perforations (62) de ladite seconde cou- 25 che pour créer un trajet tortueux qui empêche le jus de ladite viande de passer à travers ledit emballage de film extensible (18).

4. Conditionnement (10) selon l'une des revendica- 30 tions 1 à 3, dans lequel ledit emballage de film extensible (18) inclut une couche de film extensible (18) et une couche à auto-scellement (68), chacune étant sensiblement perméable à l'oxygène, lesdites performations (62) passant à l'origine à travers la- 35 dite couche de film extensible (18) et ladite couche à auto-scellement et étant sensiblement bouchées par ladite couche à auto-scellement (68).

5. Conditionnement (10) selon l'une des revendica- 40 tions 1 à 4, dans lequel ladite couche de film extensible (18) est constituée de polychlorure de vinyle et ladite couche à auto-scellement est composée d'une cire ou d'un polymère de faible masse molé- culaire. 45

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