EP0699157B1

EP0699157B1 - Packaging for increased food product shelf life

Info

Publication number: EP0699157B1
Application number: EP94918018A
Authority: EP
Inventors: Michael P. Gorlich; Robert F. Mcpherson
Original assignee: World Class Packaging Systems Inc
Current assignee: World Class Packaging Systems Inc
Priority date: 1993-05-20
Filing date: 1994-05-16
Publication date: 2000-01-12
Anticipated expiration: 2014-05-16
Also published as: JP2001294278A; NZ267278A; DE69433041D1; EP0699157A1; CA2163230C; EP0899209A3; DE69422620D1; WO1994027868A2; AU6952094A; EP0899209B1; KR100320356B1; CA2163230A1; WO1994027868A3; ATE188660T1; ATE247028T1; EP0899209A2; AU688329B2; EP0949147A1; JPH08510708A; DE69422620T2

Abstract

An apparatus for making a modified atmosphere package includes a plurality of packaging stations. A rotary conveyor is provided for moving trays from one station to the next. The rotary conveyor has a platform which carries a plurality of trays. One of the packaging stations is adapted to load the trays on to the platform. Another station is adapted for loading a food product into the trays. A further station is adapted to unload the trays from the platform. An apparatus is provided for replacing the ambient atmosphere in the trays with an atmosphere reduced in oxygen content before the trays are covered with a film.

Description

THIS INVENTION relates to a package, and more specifically to a package for food products. In particular the invention relates to a package for food products which is such that the food product packaged within the package may be maintained in one condition under certain circumstances and then converted to another condition. For example, during transportation the food package might maintain an inert gaseous atmosphere and then, when the package reaches a supermarket or other retail outlet, the food package will permit exposure of the food product to the ambient atmosphere. While a wide variety of food products can be packaged in accordance with the teachings of this invention, it is particularly advantageous in connection with the packaging of meat in a modified atmosphere package such that the meat may be transported in a relatively inert atmosphere and then caused to bloom when it reaches a retail outlet by exposure to oxygen.
Historically, meat products have been butchered and packaged in each supermarket or other retail outlet. It has long been recognized that this arrangement is extremely inefficient and expensive. Instead, it would be preferable to permit the meat to be butchered and packaged at an efficient facility which benefits from economies of scale and thereafter shipped to individual supermarkets or other retail outlets.
In the past, this desirable goal has not been achievable because most consumers prefer to buy meat which is red in color. However, after being exposed to oxygen, the meat maintains its red color for only one or two days. Thereafter it turns to a purple color which is undesirable to most consumers. Therefore, if the meat was butchered and packaged in one location and then shipped to another location for eventual sale, by the time the package reached the retail outlet the meat would have undergone the transformation to the purple color and would be effectively unsaleable.
To overcome these problems, there have been a number of efforts to maintain the food product in a first atmosphere during shipping and a second atmosphere when the meat product is ready for retail sale. It is not believed that any of these techniques have yet achieved significant commercial acceptance. Therefore, it is highly desirable to provide a package that would permit remote meat preparation, and subsequent sale several days later.
One problem is that while the need for such a package is great, consumers may not be willing to invest much money in elaborate packages. Thus, it would be highly desirable to have a package that is convertible between two very different packaging conditions, and yet is very economical. Moreover, it is also advantageous for the package to look similar to packages to which consumers are currently accustomed.
One attempted solution to these problems is to use a dual layer cover over a plastic package containing the meat product. The upper cover is gas impermeable and may be removed to expose a lower cover that is air permeable. Thus, the package may be shipped with the upper cover intact so that an inert gaseous atmosphere may be maintained within the package during shipping. Then the upper cover may be removed at the supermarket leaving the lower cover. Since the lower cover is oxygen permeable, it allows the meat to bloom in the presence of oxygen.
Conventionally, such dual layer packages have been implemented by adhesively securing the upper layer to the lower layer and thereafter heat sealing or otherwise securing both layers to the package itself. However, when the upper layer is removed the adhesive may be retained on the lower layer, interfering with the ability of the lower layer to pass oxygen. Also, when removing the top layer it may be difficult to avoid tearing or otherwise removing the lower layer. Moreover, it is difficult to produce such a package with controlled delamination of the two layers.
While various elaborate techniques have been conceived for avoiding the interference between the layers, these approaches generally add cost and complexity to the packaging. Moreover, the removal of the upper layer ( which is sealed to the lower layer) without removing the lower layer is problematic. Although attempts have been made to overcome these problems, no commercially viable solution has been achieved.
According to GB-A-2251540 an open top of a package is provided with two support surfaces spaced apart, each being provided for the connection of a plastic sheet.
Domed meat packages have been used in the past to contain large cuts of meats such as chickens or roasts. However, these packages have suffered from a number of drawbacks.
It is desirable to control the atmosphere within the meat package to delay the aging of the food product and to extend its shelf life in the supermarket. For example, by providing low oxygen environments, the shelf life of the food product can be extended from a few days to as long as two weeks or more perhaps.
In order to make the customer feel comfortable with the food packaging, the customer should be able to view a substantial portion of the food product. In order to maintain a desired atmosphere around the package, a package which is somewhat larger than the food product is required. However, with a large, relatively heavy meat product it is difficult to allow for spacing around the food product and yet maintain the product in an attractive fashion within the container.
Moreover, since the consumer would normally desire that he or she be able to see the food product, the spacing becomes visible to the consumer. The consumer may believe that the package is too large and wasteful. Moreover, if the product is substantially larger than the food product, the food product may move around during transportation and handling, and the package itself may be indented or otherwise damaged.
In the past, deep draw packages may have been used for this type of packaging. However, deep draw packages become difficult to form at large sizes and may experience significant deformation of the packaging material. These packages are particularly susceptible to the formation of thin spots and to the indenting and collapsing of the corner regions.
International Patent Application No. WO91/03407 discloses a packaging for perishable goods which comprises a clear plastics material domed lid over a base, with the lid sealing the packaging, within which an inert gaseous atmosphere is maintained.
According to this invention there is provided a package for facilitating gas exchange, comprising: an upper substantially rigid domed package portion, said domed package portion including an upper flange extending away from the remainder of said domed package portion; a lower substantially rigid, dished package portion which may have a lower flange extending outwardly from the remainder of said dished package portion; wherein each of said portions include sealing regions for sealing connection to the other package portion; and one or more apertures are provided in one of said package portions for permitting selective gas escape from said package, the or each aperture being covered by a gas permeable plastic sheet secured to said package at a first location, said gas permeable plastic sheet being further covered by a removable gas impermeable plastic sheet.
Preferably said sheets are unconnected to one another except by way of one of said package portions.
Conveniently said upper and lower flanges are aligned and overlap along their outermost extensions.
Advantageously said upper flanges substantially overlap said lower flanges only to either side of their outermost extensions.
Preferably said upper flanges overlap less than all of said lower flanges, each overlapping region of each upper flange being protected from accidental engagement.
Conveniently said upper and lower flanges are substantially aligned at their points of outermost extension, said upper flanges overlapping said lower flanges to either side of the points of outermost extension of said upper flanges.
Thus, the present applicant has appreciated that it would be desirable to form a domed package rather than to use the deep draw plastic forming technique. With the domed package, the product may protrude above the sealing flanges that connect the upper and lower package portions. It is also possible to form the package portions from different materials adapted to particular packaging needs. For example, it may be desirable to form the bottom portion out of foam material and the top out of transparent plastic.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which :-
Figures 1a, 1b and 1c are simplified cross-sectional views showing three stages in one embodiment of a process for making a package in accordance with the present invention;
Figure 2 is a partial, enlarged, top plan view of the package shown in Figure 1a;
Figure 3 is a partial, enlarged, top plan view of the package shown in Figure 1b;
Figure 4 is an enlarged, cross-sectional view of one embodiment of a packaging apparatus for accomplishing the process steps shown in Figure 1; and
Figure 5 is an enlarged, cross-sectional view of the packaging apparatus of Figure 4, shown in position to accomplish the process step shown in Figure 1c.
Referring to the drawings, wherein like reference characters are used for like parts throughout the several views, a packaging process for packaging a large meat product "A" is shown in Figure 1 and includes the steps a, b and c. In step a, the food product "A" is shown contained within a dish-shaped plastic package portion 310 which is supported by a peripheral flange 312 on a member 314.
The package portion 310 may be formed of a variety of conventional materials including any known plastic packaging material. In many instances, it may be desirable to form the lower package portion 310 of molded foamed plastic so that the package portion will be relatively rigid.
Referring to Figure 1, step b, an upper package portion 318 is shown in spaced relation to the lower package portion 310 over the food product "A". the package portion 318 is domed and includes a peripheral flange 320. Like the package portion 310, the upper package portion 318 may be formed of a variety of conventional plastic materials. However, in many instances, it may be desirable to form the upper package portion 318 out of relatively rigid, molded transparent plastic material. This allows the food product "A" to be viewed within the food package. Advantageously, both the portions 310 and 318 are preformed of relatively rigid, molded plastic material.
As shown in Figure 1, step c, the upper and lower package portions 318 and 310 may be joined along their peripheral flanges 320 and 312 by an apparatus 322 which presses the peripheral flange 320 of the upper package portion 318 downwardly onto the peripheral flange 312 of the package portion 310. If desired, the apparatus 322 may be a heat seal machine which causes heat sealing of the juxtaposed flange portions thereby connecting the materials.
The advantage of holding the upper domed package portions 318 in spaced juxtaposition with the lower package portion 310 is that the gaseous environment within the package may be transformed prior to the sealing step c shown in Figure 1. For example, the air inside the package may be exhausted, and a desired gas may be supplied in its place. The desired gas may be one which is relatively low in oxygen content so that the shelf life of the food product may be extended. For example, the gas may be relatively higher in either carbon dioxide and/or nitrogen than normal atmospheric air in order to prevent or diminish the oxidation processes that shorten the life of the meat product "A".
As shown in Figure 2, the lower package portion 310 may be maintained in a desired arrangement by a set of two pairs of opposed guides 324. Each of the guides 324 is arranged in a substantially tangential arrangement to the curved sides of the lower package portion 310 so as to abut with a sealing region 326. The sealing region 326 provides the point of attachment to the upper package portion 318. It can also be seen in Figure 2 that the lower package portion 310 may include an outwardly extending flange 328 on either of two opposed ends of the package portion 310. These flanges are herein termed lower flanges. While the package 310 portion shown in Figure 2 has an oval configuration, the cross-sectional configuration of the package may assume one of a variety of different shapes.
Figure 3 shows the positioning of the upper package portion 318 over the lower package portion 310. The upper package portion 318 includes a pair of opposed bluntly pointed end flanges 334, herein termed upper flanges, which interact with and are constrained between each set of guides 324. The outwardly extending upper flanges 334 extend over two vertically mounted filling tubes 330 such that the tubes 330 do not generally guide the positioning of the upper package portion 318 in the horizontal plane. This is accomplished substantially by the guides 324.
The upper flanges 334 and the lower flanges 328 are aligned and overlap along their outermost edges or extensions 332. In the regions 336, located on either side of their outermost edges 332, the upper flanges 334 extend past the outermost edges 332 of the lower flanges 328 so that there is a region of overhang of each upper flange 334 over the lower package portion 310.
A gas exchange portion 358 is provided on the upper package portion 318. The portion gas exchange 358 includes one or more apertures 360 formed in the package portion 318. These apertures are covered by a first sheet in the form of a circular plastic film layer 362 which may be permeable to atmospheric air. The first sheet 362 is sealed to the package portion 318 at 364. Attached over the first sheet 362 is an upper sheet in the form of a fluid impermeable plastic film 366 which is sealed at 368 to the upper package portion 318. The first sheet 362 and the upper sheet 366 are unconnected to one another except by way of the package portion 318. When desired, the upper sheet 366 may be peeled away to allow gas exchange through the first sheet 362 via the apertures 360.
Figure 4 shows a packaging machine for achieving the package operation shown in Figure 1. In order to illustrate that a variety of package shapes may be utilized, the package 338 shown in Figure 4 is of a slightly different shape than the package shown in Figure 1. In particular, the lower package portion 310 is deeper than the package portion 310 shown in Figure 1, and the abruptness of both the lower and the upper package portions 318 and 310 is greater in the embodiment shown in Figure 4.
The lower package portion 310 rests in a conforming tray 340 which conforms to its outside configuration and supports the peripheral flange 312. The upper package portion 318 has the flange region 336 resting atop the filling tube 330.
The filling tube 330 is reciprocal up and down within a slot 342. However, the extent of its upward extension is controlled by the overhanging edge 344 of the adjacent guide 324. Each tube 330 includes an outer cylinder 330a and an inner cylinder 330b.
The outer cylinder 330a includes a set of "O" rings 346 which prevent leakage around the tube 330. A pin 348 is provided to control the extent of downward movement of the tube 330 and to prevent its rotation about its lengthwise axis. Within the center of the tube 330 is a bore 350 which is capable of conveying gas to or from the interior of the package to or from the passageway 352. Thus, gas may pass via the passageway 352 to or from the interior of the package shown in the configuration of Figure 4.
A pressurized gas supply passageway 372 is connected to a source (not shown) of pressurized gas. When desired, pressurized gas may be communicated via the passageway 372 to act on the lower end of the outer cylinder 330a. This causes the tube 330 to move to its upper position shown in Figure 4.
Juxtaposed over the upper package portion 318 is a pusher bar 354 and a sealing bar 356. The sealing bar 356 may be a conventional heat sealing bar which heat seals the flanges of the upper package portion 318 to those of the lower package portion 310.
The vacuum chamber cover 390 seals to the lower chamber 392 though inner and outer peripheral seals 394 and 396 and the abutment of gasket 398 on the lower chamber 392. A valved passage 400 is provided for pulling a vacuum inside the chamber defined by the cover 390.
The method and apparatus of the present invention may be implemented in the following fashion. The lower package portion 310, loaded into the conforming tray 340, is supported by its peripheral flanges 312. Then a meat product "A", if not already loaded, may be loaded inside the package portion 310. Next, the relatively rigid top or upper portion 318 is aligned over the lower package portion 310 but resting on the top of the filling tubes 330 as shown in Figure 4.
Initially, the air within the package is exhausted through both the passage 400 and the bore 350 to the passageway 352. Then, with the passage 400 closed, a desired gaseous environment is passed through the passageway 352 and the bore 350 into the package. This gaseous environment may be one which is relatively poor in its concentration of oxygen and relatively higher (with respect to normal ambient atmosphere) with respect to its carbon dioxide and/or nitrogen content. The result of such an environment is to extend the shelf life of a meat product. This is because the presence of oxygen causes the meat product to age and discolor.
After the desired environment has been established, the gas filling tubes 330 are pushed downwardly by the pusher bar 354 into their passageways 342 until the pins 348 engage the top of the slots 380. In this position, shown in figure 5, the upper package portion 318 is in abutment with the lower package portion 310. At this point, the sealing regions 326 are likewise in abutment. The package is thereafter sealed along the regions 326 of the upper and lower package portions 310 and 318 to provide an air tight seal between the two package portions. This is accomplished through the sealing bar 356 which may, in one advantageous embodiment, cause heat sealing of the components together. The sealing bar 356 reciprocates with the pusher bar 354. However, the pusher bar 354 pushes the tubes 330 below the flanges to ensure that, regardless of the package thickness, the tubes 330 do not interfere with the sealing process.
The completed package 338 may be removed by raising the cover 390 with the sealing bar 356 and pusher bar 354. The package 338 may be removed from the conforming carrier 340. This may be accomplished in batch or continuous fashion as desired.
The cycle may be repeated after the gas tubes 330 are reciprocated to their upper position. This is achieved by supplying air pressure to the upper cylinders 330a. The air pressure is released through a relief valve (not shown) when the tubes 330 are pushed downwardly by the pusher bar 354.
The positioning of the upper and lower packaging portions 310 and 318 with respect to one another is assured by the provision of the guides 324 and the filling tubes 330 which interact with the special package shape to ensure exact juxtaposed position of the parts relative to one another. Moreover, the flange regions 336 of the upper package portion 318 maintain the separation of the package when they abut with the filling tubes 330.
Firstly, the lower package portion 310 is inserted into the conforming carrier 340, guides by tubes 330 and guides 324. Then, the upper package portion 318 is located on the tubes 330, positioned by the guides 324. Thereafter, the cover 390 is closed and the process may be repeated.
In many applications, particularly those involving red meat, it may be desirable to withdraw the low oxygen atmosphere from the container at the point of sale. Otherwise, the package with its low oxygen environment will cause the meat to have a purplish color. Thus, in the supermarket, the upper sheet 366 of fluid impermeable film may be peeled back. This allows ambient atmosphere to enter the package so that the meat will take on a reddish color.
The provision of the flange overhang 336 of the upper package portion 318 over the lower package portion 310 facilitates the removal of the domed upper package portion 318 in use. Moreover, the concealed location of the overhang 336 diminishes the possibility of accidental opening.

Claims

A package for facilitating gas exchange, comprising:

an upper substantially rigid domed package portion (318), said domed package portion including an upper flange (334) extending away from the remainder of said domed package portion;

a lower substantially rigid, dished package portion (310) which may have a lower flange (328) extending outwardly from the remainder of said dished package portion;
wherein:

each of said package portions (318, 310) includes sealing regions (312, 320) for sealing connection to the other package portion; and

one or more apertures (360) are provided in one of said package portions for permitting selective gas escape from said package, the or each aperture being covered by a gas permeable plastic sheet (362) secured to said package at a first location (364),said gas permeable plastic sheet being further covered by a removable gas impermeable plastic sheet (366).
The package of claim 1 wherein said sheets (362,366) are unconnected to one another except by way of one of said package portions (318).
The package of claim 1 or claim 2, wherein said upper and lower flanges (334,328) are aligned and overlap along their outermost extensions (332).
The package of claim 3, wherein said upper flanges (334) substantially overhang said lower flanges (328) only to either side (336) of their outermost extensions (332).
The package of claim 2, wherein said upper (334) and lower (328) flanges are substantially aligned at their points of outermost extension (332), said upper flanges (334) overlapping said lower flanges (328) to either side (336) of the points of outermost extension (332) of said upper flanges (334).