Package for storing and cooking food with temperature-activated ventilation

Abstract

A package suitable for storing and cooking foods without user manipulation includes a venting mechanism actuated primarily or exclusively by temperature, rather than pressure. A vent hole can be sealed by a patch attached by a thermoplastic adhesive having a selected, well characterized Tg, or the patch itself can be a thermoplastic polymer having a selected Tg. The patch can be convection-heated, or a microwave absorbing susceptor material can be applied to the adhesive or patch for direct microwave heating. The patch can include a region that is melted by convection or by a susceptor material. A porous patch can be sealed by a low melting temperature polymer or by thermally sensitive ink. And/or, microwave susceptor material can be applied directly to a package wall and can melt a ventilation hole through the wall when a specified amount of microwave energy has been applied.

Claims

1. A package suitable for containing a food item both during storage of the food item and during cooking of the food item, the package comprising: a container formed by at least one container wall, said container walls surrounding a package interior and being substantially impermeable to gasses; a ventilation hole penetrating one of the container walls; and a sealing patch applied to the container wall so as to seal the ventilation hole; wherein the sealing patch comprises a porous layer that is penetrated by a plurality of pores or microperforations, said pores or microperforations being sealed by a sealing material that flows out of the pores or microperforations due solely to gravity when the container is heated to the specified venting temperature, thereby allowing the package interior to be vented through the venting hole and the pores or microperforations.

2. The package of claim 1, wherein the sealing material is a crystallizable polymer.

3. The package of claim 1, wherein the sealing material is a temperature sensitive ink.

4. The package of claim 3, wherein the sealing patch is a packaging label, and the temperature sensitive ink presents a visible indicium on the packaging label.

5. The package of claim 1, wherein the porous layer remains adhered to the package wall after the package interior has been vented through the pores.

6. The package of claim 1, wherein the porous layer is made from an open-mesh or non-woven high density polyethylene (HDPE).

7. The package of claim 6, wherein the porous layer includes pores having diameters of at least ⅛ inches.

8. The package of claim 1, wherein the sealing material is a sealing layer that is laminated onto the porous layer.

9. The package of claim 8, wherein the sealing layer is substantially impermeable to gasses.

10. The package of claim 8, wherein the sealing layer is microporous or microperforated, so as to provide limited gas permeability, thereby enabling a modified atmosphere having an O.sub.2 concentration less than 20.9% O.sub.2 and CO.sub.2 concentration of greater than 0.3% to be established in the package interior when fresh, respiring produce is contained within the package.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A is a perspective view of a package having a ventilation hole shown beside a sealing patch in an embodiment of the invention where the patch is attachable to the bag by a thermoplastic adhesive;

(2) FIG. 1B is a perspective view of the package of FIG. 1A shown with the patch attached to the bag;

(3) FIG. 1C is a perspective view of the package of FIG. 1B shown after heating and partial detachment of the patch;

(4) FIG. 1D is a perspective view of an embodiment similar to FIG. 1C shown after heating of the patch has caused ventilation channels to form in the patch adhesive;

(5) FIG. 2 is a perspective view of an embodiment similar to FIG. 1A, wherein a microwave-absorbing susceptor material has been added to the thermoplastic adhesive;

(6) FIG. 3A is a perspective view of a package having a ventilation hole shown beside a sealing patch in an embodiment of the invention where the patch is made from a mechanically competent thermoplastic polyurethane that is self-adhesively applicable to the bag by application of pressure and heat to the patch;

(7) FIG. 3B is a perspective view of the package of FIG. 3A shown after heating and partial detachment of the patch;

(8) FIG. 4A is a perspective view of an embodiment wherein the sealing patch is made from a susceptor-meltable plastic to which a microwave absorbing susceptor material has been applied;

(9) FIG. 4B is a perspective view of the embodiment of FIG. 4A shown after the susceptor material has been heated by microwaves and has melted a hole through the patch;

(10) FIG. 4C is a perspective view of an embodiment similar to FIG. 4A, wherein the microwave susceptor material is applied directly to a susceptor-meltable region of a wall of the package;

(11) FIG. 4D is a perspective view of the embodiment of FIG. 4C shown after the susceptor material has been heated by microwaves and has melted a hole through the package wall;

(12) FIG. 5A is an exploded view of a laminate patch that includes a porous layer and a pore-sealing layer;

(13) FIG. 5B is a perspective view of the assembled patch of FIG. 5A, shown from above;

(14) FIG. 5C is a perspective view of the assembled patch of FIG. 5A, shown from below, whereby the applied adhesive is visible;

(15) FIG. 5D is a perspective view of the patch of FIG. 5B applied to seal a vent hole in a package according to an embodiment of the invention; and

(16) FIG. 5E is a perspective view of the embodiment of FIG. 5D, shown after the patch has been heated and the sealing layer has melted, allowing the package interior to be vented through the pores of the porous layer.

DETAILED DESCRIPTION

(17) The present invention is a food storage and cooking package which includes a venting mechanism that is actuated primarily or exclusively by temperature rather than by pressure, thereby providing a storage and cooking solution that does not require user manipulation, and does not require a high free moisture content within the package, where free moisture is defined as moisture that is converted into heated vapor during cooking. In embodiments, a temperature-related visual indication is provided by the venting mechanism that alerts a user as to the cooking status of the food contents.

(18) The disclosed package is sometimes referred to herein as a “bag.” However, it should be understood that the term is used generically herein to refer to any package that is able to contain food during storage and during cooking, including a rigid tray that includes a lidding film sealed thereto.

(19) With reference to FIGS. 1A and 1B, in embodiments the disclosed bag 100 includes one or more ventilation holes 102 that are covered by an impermeable label or patch 104 that is adhered to the bag by a thermoplastic adhesive 106, which can be a pressure-sensitive adhesive, that has a well-characterized glass transition temperature Tg, and therefore a well-characterized temperature at which the adhesive 106 will soften and the patch 104 will become partially or fully detached, as shown in FIG. 1C, and/or channels 108 will be formed through the surrounding adhesive whereby the package is vented, as shown in FIG. 1D. In some of these embodiments the adhesive is heated by convection due to heating of the air and/or moisture 110 within the bag 100.

(20) In some of these embodiments, the thermoplastic adhesive 106 is applied only on the rear face of the label or patch 104 at its periphery, so that the center of the patch or label 104 over the vent hole 102 is free of adhesive. In other embodiments, an adhesive 106 is applied uniformly to the patch or label 104, and then is deactivated in the region that overlaps the vent hole 102. For example, in embodiments a uniform layer of adhesive 106 is applied to a sheet of label material and protected by a backing layer. During manufacture, the patches or labels 104 are cut or stamped from the sheet of material, the backing layers are removed from the patches 104, and a blocking gel or powder, or a small backing plate, is applied to the center of each patch 104, so that after the patch 104 is applied to the bag 100, the perimeter of the patch 104 is sealed to the bag 100, but the contents 112 of the bag are not exposed to the adhesive.

(21) With reference to FIG. 2, in other embodiments that are useful for microwave cooking, a microwave absorbent material, referred to herein as a microwave “susceptor” material, such as activated aluminum flakes, carbon powder, or a microwave absorbent ceramic, is mixed with the adhesive 106, such that the adhesive 106 is directly heated by applied microwaves and the patch 104 detaches from the bag 100 after a predetermined amount of microwave energy has been applied.

(22) With reference to FIG. 3A, in still other embodiments, a patch 300 made of thermoplastic urethane (TPU) material is applied to cover the vent hole(s) 102, for example using applied heat and pressure, such that no additional adhesive is required. The applied TPU 300 is formulated to have a glass transition temperature Tg that will cause the TPU patch 300 to detach from the bag 100, as shown in FIG. 3B, at a desired temperature, either due to convective heating by water vapor and/or hot air with in the bag, or in embodiments due to direct heating of a microwave susceptor material included in the TPU 300.

(23) With reference to FIG. 4A, in some embodiments microwave susceptor material 400 is applied to a non-porous label material 104, which can be a TPU, such that the susceptor material 400 melts one or more holes 402 in the label 104 when sufficient microwave energy has been absorbed, as shown in FIG. 4B. In similar embodiments, with reference to FIG. 4C, at least a portion of the bag 100 is made from a plastic or other material that will melt when heated, and the microwave susceptor material 400 is applied directly to the susceptor-meltable portion of the bag 100, such that one or more vent holes 402 are formed when the susceptor material is sufficiently heated by applied microwaves and the underlying bag material is melted, as shown in FIG. 4D.

(24) In various embodiments, with reference to FIGS. 5A through 5D, a porous material 500 is used for the label or patch 506. The pores 502 of the patch material 500 are sealed by a crystallizable polymer or other material 504 having a desired Tg or other thermal characteristics. With reference to FIG. 5E, the patch 506 covers the vent opening(s) 102, and in these embodiments the patch material 500 remains adhered about its perimeter 106 to the underlying bag 100, while “melting” of the applied sealant 504 causes the pores 502 in the patch material 500 to be opened. In similar embodiments, a temperature sensitive ink is used to seal the pores in the patch.

(25) In some of these embodiments, the patch or label 506 is made of a thermal laminate comprising a covering film 504 applied to an open-mesh or non-woven, high density polyethylene (HDPE) 500, which in some embodiments includes mesh openings 502 of at least ⅛″ diameter distributed throughout the mesh or non-woven 500. In the embodiment of FIGS. 5A through 5C, a pressure sensitive adhesive 106 is applied to the rear face of the label or patch 506 only on the periphery of the patch or label 506, so that the center of the patch or label 506 above the vent hole 102 is free of adhesive 106. In other embodiments, as discussed above, the adhesive 106 is applied uniformly to the rear surface of the patch or label 104, but is deactivated in a central region so that the interior of the bag 100 is not exposed to the adhesive 106 through the vent hole 102. For example, in embodiments a uniform layer of adhesive is applied to a sheet of label material and protected by a backing layer. Then, during the printing and manufacture of the patch or label 506, the center of the patch or label 506 is deadened with an organic or inorganic coating, so that when the patch or label 506 is applied to the package 100, only the perimeter of the patch or label 506 is sealed to the bag 100, and the contents of the bag 100 are not exposed to the adhesive over the vent hole region 102.

(26) In some of these embodiments, the covering film 504 is a pore-blocking polymer that renders the label 506 essentially impermeable to gases. In other embodiments, the covering film 504 is a microporous film or microperforated film, configured so that a modified atmosphere packaging (“MAP”) solution is provided that allows a limited exchange of gases between the environment and the interior of the bag during refrigerated storage, thereby establishing a modified internal atmosphere, such as an atmosphere having an O2 concentration less than 20.9% O2 and CO2 concentration of greater than 0.3%, when storing fresh, respiring produce 112, so as to prolong the freshness of the produce 112.

(27) The Tg or melting temperature of the covering layer 504 is lower than the temperature of the HDPE mesh or non-woven 500, so that when the package 100 is heated in a microwave oven or other cooking environment, the covering layer 504 peels or shrinks away from the underlying HDPE mesh or non-woven 500 and the package 100 is vented.

(28) 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.

(29) The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein and is not inherently necessary. However, 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 of 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.