Patent Application
20180327166
The invention relates to packaging, and more particularly, to modified atmosphere packaging.
The quality and shelf-life of many perishable products is critically dependent on the nature and quality of the packaging in which it is contained. For many food products, such as meats and cheeses, optimal preservation is obtained by removing as much atmosphere as possible and hermetically sealing the product. However, fresh produce continues to undergo respiration while being transported and stored, and will quickly perish and spoil if placed in a hermetically sealed container.
One approach for packaging fresh produce is to use packing that is well ventilated, so that the atmosphere within the container approximates the ambient atmosphere, thereby allowing unimpeded respiration by the contained produce while it is transported and stored. This approach avoids the premature spoilage that can result from hermetic packaging, but does nothing to enhance or prolong the quality and shelf life of the produce beyond what would be obtained if the produce were not contained in a package.
Another approach is to artificially slow the respiration and other metabolic processes of produce by refrigeration or other cooling methods, so that the produce remains alive and fresh, but ages more slowly. Cooling is certainly an effective means to extend the shelf life of produce, but cooling methods can be expensive. Also, it may be desirable to extend the shelf life of fresh produce beyond what can be accomplished by cooling alone.
Another approach for extending the shelf life of fresh produce, which can be implemented either alone or in combination with cooling, is to enclose the produce in packaging that allows only a very limited rate of gas exchange between the interior of the package and the surrounding environment. By tailoring the gas exchange rate to the specific type and quantity of contained produce, and taking into account the temperature and other factors, it is possible to induce a modified atmosphere within the package, whereby the respiration of the contained produce causes the oxygen level to be reduced and the carbon dioxide level to be increased, thereby slowing the metabolism of the produce and extending its shelf life without causing the contained produce to perish and spoil. This approach is generally referred to as equilibrium modified atmosphere packaging (“EMAP” or simply “MAP” as used herein). The result can be increased quality and longer shelf life, less waste from spoiled produce, better inventory control, and appreciable overall savings for the food industry at both the retail and wholesale levels.
MAP can be implemented in any of several ways. In some instances, MAP can be achieved simply by selecting an appropriate packaging material and controlling the thickness of the material so as to provide a limited permeability to oxygen and carbon dioxide. However, this approach places significant constraints on package size, packaging material, overall package strength and durability, and packaging costs. It is therefore applicable only to a limited range of circumstances.
In a related approach, part or all of a package can be constructed from a microporous material that provides a well-defined gas permeability. Microporous materials can be created by including small filler particles, such as silica or calcium carbonate, in a polymer formulation, and orienting the film in the longitudinal and/or cross direction so as to create microscopic pores throughout the film. However, the methods by which microporous films are produced limit the types and thicknesses of packaging materials that can be used. Also, microporous materials can be prohibitively expensive for use as a packaging material. In addition, these microporous materials are often opaque, such that making the entire package from microporous material can be unacceptable from a consumer standpoint, where great importance is given to the observation of the appearance of the fresh produce when making a selection.
Another approach is to use a packaging material that is essentially impermeable to gases, and to penetrate the material with one or more “microperforations,” typically having diameters measuring in the tens of microns to hundreds of microns. For example, microperforations can be made using pins or a laser during manufacture of a web, and then the web can be used to form produce bags or film tops for produce trays and other rigid containers. In the case of rigid or semi-rigid trays, this approach can be effective for packages that are intended for single use, but the approach is problematic for applications where it is desirable to re-seal a rigid or semi-rigid package after initial use, and to reestablish a modified atmosphere to prolong the shelf life of the remaining contents.
Microperforation can be challenging in cases where it is desirable for the package to be fully rigid or semi-rigid, and possible re-sealable, because it can be difficult to accurately and consistently micro-perforate the walls of a rigid or semi-rigid container, especially if the container includes an elastomeric inner sealant layer in addition to the rigid or semi-rigid outer layer. One successful solution is presented in co-pending application U.S. Ser. No. 14/941,028, filed on Nov. 13, 2015, also by the present inventor, which is incorporated herein by reference in its entirety for all purposes. Nevertheless, this approach may not be optimal in all circumstances.
Another MAP approach that is applicable to rigid and semi-rigid containers is to provide a single, macroscopic opening or hole, typically a few millimeters to a centimeter in diameter, somewhere in the container, and then cover the macroscopic opening with a microperforated or microporous “patch.” This MAP hole and patch approach can be highly effective, and can be relatively easy and cost-effective to implement for rigid and semi-rigid containers. However, finding a suitable location for the hole and patch can be problematic.
The lid of a rigid or semi-rigid container is generally a primary display surface, and so it may be desirable to cover the entire lid with a product identifying and branding label, which would interfere with the patch. Also, it may be undesirable for esthetic reasons to put the hole and patch on the lid, where they will be highly visible. In addition, the sides of a rigid or semi-rigid container often provide important visibility to consumers who wish to view the contents of the package. Accordingly, it may also be undesirable to place the hole and patch on a side of the container. And, of course, placement of the patch and hole on the bottom of the container is problematic, because it is likely that the patch will be blocked by whatever surface the package is resting on.
Furthermore, rigid containers are often packed closely together and stacked on top of each other during storage, shipment, and even when on display for sale, making it likely that a patch might be blocked by an adjacent container no matter where the hole and patch are located.
What is needed, therefore, is a rigid modified atmosphere packaging container with a rigid lid having an MAP hole and patch that are not located on a highly visible surface and are not likely to be blocked when the container is resting on a surface and/or included in a stack of containers.
A rigid modified atmosphere packaging container with a rigid lid is disclosed having an MAP hole and patch that are not located on a highly visible surface and are not likely to be blocked when the container is resting on a surface and/or included in a stack of containers. According to the present disclosure, a region of the container bottom is raised in comparison to the remainder of the bottom surface, such that an open space or cavity is created, referred to herein as the MAP cavity. A macroscopic hole and MAP patch are provided on the bottom of the container inside of the MAP cavity, and is covered by a semi-permeable patch such as a microperforated or microporous patch that permits a limited gas exchange through the hole.
The MAP cavity extends to an edge of the bottom surface, so that air is readily exchanged between the MAP cavity and the ambient surroundings. As a result, placement of the container on a flat surface or on top of another container does not restrict the exchange of air between the MAP cavity and the surrounding atmosphere.
In embodiments, the sides of the container are slanted inward, so that air passages are created between the containers when they are arranged in a stack. As a result, air is easily exchanged between the surrounding air and all of the MAP cavities of all of the containers in the stack. In some embodiments, the MAP cavity extends to more than one bottom edge of the container.
The present invention is a rigid or semi-rigid container configured for modified atmosphere packaging of produce. The container includes a base having a bottom and at least one side joined to the bottom by a bottom edge, a lid removably engageable with the base so as to form a seal therebetween, a raised region formed in the bottom of the container base and extending to the bottom edge thereof, so that when the container bottom is placed on a flat surface the raised region and flat surface form a cavity into which air from an environment surrounding the container can enter the cavity by passing under the bottom edge, a hole formed in an upper surface of the raised region and penetrating the container bottom, and a semi-permeable patch installed over the hole and configured to permit a limited exchange of gases between an interior of the container and the surrounding environment, so that a modified atmosphere is created within the container when respiring fresh produce is contained therein.
In embodiments, the lid can be re-engaged with the base after removal thereof so as to re-establish a modified atmosphere within the interior of the container when fresh produce remains contained
In any of the above embodiments, the side can be slanted outward from the bottom edge, so that when the container is placed against a vertical surface or next to an adjacent container having a similar shape, a passage is formed along the side of the container through which air can flow to the bottom edge and from thence to the patch.
In any of the above embodiments, the patch can be made from a material that is naturally semi-permeable to gases, a microporous material, or a material that is substantially impenetrable to gases, but microperforated so as to allow the limited exchange of gasses.
Any of the above embodiments can further include sealant layers applied to interior surfaces of the base and lid, the sealant layers being sealable to each other when the lid is engaged with the base so as to form a hermetically sealed junction therebetween. In some of these embodiments the sealant layers comprise at least one of polyacrylonitrile resin and polyester film.
In any of the above embodiments, the hole can be between 1 mm and 10 mm in diameter.
In any of the above embodiments, the patch can be adhered to the upper surface of the raised region by an adhesive that is applied to a perimeter of the patch but does not overlap the hole.
And in any of the above embodiments, the raised region can extend to a plurality of bottom edges that join a plurality of sides to the container bottom.
The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.
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The patch 108 can include a material that is naturally gas permeable or microporous, or it can be made from a gas impervious material that has been microperforated by pins or by a laser. It can be attached to the bottom of the container body 102 by an adhesive that has been applied about a perimeter of the patch 108, so that the adhesive surrounds the hole 106 but does not interfere with gas exchange through the region of the patch 106 that is/are directly over the hole 106.
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The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. Each and every page of this submission, and all contents thereon, however characterized, identified, or numbered, is considered a substantive part of this application for all purposes, irrespective of form or placement within the application.
This specification is not intended to be exhaustive. Although the present application is shown in a limited number of forms, the scope of the invention is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof. One or ordinary skill in the art should appreciate after learning the teachings related to the claimed subject matter contained in the foregoing description that many modifications and variations are possible in light of this disclosure. Accordingly, the claimed subject matter includes any combination of the above-described elements in all possible variations thereof, unless otherwise indicated herein or otherwise clearly contradicted by context. In particular, the limitations presented in dependent claims below can be combined with their corresponding independent claims in any number and in any order without departing from the scope of this disclosure, unless the dependent claims are logically incompatible with each other.
