Patent Application
20130105471
The field of the invention relates generally to microwave packaging, and more specifically, to a flexible, laminate microwave package having a moisture and/or lipid absorbing layer for at least partially reducing moisture and/or lipids in a flexible microwave package during a heating process to facilitate crisper food items within the package.
To prepare a heated food, the microwave packaging, together with the food contained in it, has microwave energy applied to it in a microwave oven. At least some of the moisture that is generated from within the food item during the microwave cooking process tends to condense on the food item in the package or otherwise cause the food item to be wetted. Additionally, some food items may contain lipids or fats that tend to liquefy during heating. If the liquefied fats puddle in the package, the food item may be at least partially soaked in grease. Thus, breaded or bread food items will not be crisp, but rather will become soggy. For example, the preparation of fatty/greasy food items like bacon or french fries can be difficult in known microwave packages because liquefied grease or oils may pool in the bottom of the package making the items soggy. Accordingly, with existing technologies, certain food items cannot be readily prepared in a microwave oven. For example, frozen breaded food items and fat containing items that are cooked within a microwave oven typically result in the food item being soggy or grease soaked.
At least some known microwave packages attempt to improve heating of food in a microwave oven by including a metal grid layer in the laminate forming the sidewall of the packaging and/or by including a pad for absorbing at least some of the moisture generated during cooking.
The metal grid reflects at least some of the microwave energy to facilitate controlling heating of the food item, which in turn controls the liberation of moisture from the food item during heating.
The absorption of moisture is addressed by adding an absorbent pad to the package along with the food item, for example, a microwave packaging that has an absorbent insert underneath the food. The absorbent insert is intended to absorb liquid that drips off and thus regulates the moisture content within the packing to a certain extent. Because the insert covers only a small region of the surface underneath the food, condensation of liquid on the other inner surface of the packaging as well as on the outside of the packaging cannot be avoided. For example, moisture can also condense above the food and drip onto the food. Moreover, loose moisture pads are able to stick to the food item after preparation and may be at least partially consumed by the user. The pads are also less convenient, requiring additional handling, and have a negative aesthetic. Accordingly, these known absorbent pads fail to adequately address the problem of moisture absorption within a microwave cooking package during heating in a microwave oven.
Accordingly, it would be desirous to have a flexible laminate microwave package that includes a moisture absorbing layer for at least partially reducing moisture and/or lipids in the package during the microwave heating and/or cooking process to keep the heated food items crispy and more desirable to a consumer without the increased costs of a metal grid layer.
In one embodiment, a flexible microwave package system includes a front panel having a first sealing edge and an opposite second sealing edge and formed of at least a first outer layer adjacent an exterior of the flexible package. The system also includes a back panel having a first sealing edge and an opposite second sealing edge and formed of a perforated layer adjacent an interior of the flexible microwave package, an outer layer adjacent an exterior of the flexible package, and an absorbent layer extending from the first sealing edge to the second sealing edge between the perforated layer and the outer layer. The absorbent layer includes a layer of a nonwoven material. Adjacent edges of the front panel and the back panel are sealed together. Each layer contacts an adjacent layer without an intervening metallic layer.
In another embodiment, a microwave package formed of a flexible laminate includes an absorbent layer having hydrophilic properties, a reverse printed film covering an outer surface of the hydrophilic layer and forming an external surface of the package, the reverse printed film including at least one of polyester (PET), oriented polypropylene (OPP), oriented polyamide (OPA), and cellulose film, and a seal configured to join adjacent edges of the hydrophilic layer and the reverse printed PET film to define an interior volume of the package sealable from an exterior of the microwave package, where each layer contacts an adjacent layer without an intervening metallic layer.
In yet another embodiment, a microwave package formed of a flexible laminate wherein the package includes a foamed absorbent layer having hydrophilic properties, a reverse printed film covering an outer surface of the foamed hydrophilic layer and forming an external surface of the package the reverse printed film including at least one of polyester (PET), oriented polypropylene (OPP), oriented polyamide (OPA), and cellulose film, and a seal configured to join adjacent edges of the foamed hydrophilic layer and the reverse printed PET film to define an interior volume of the package sealable from an exterior of the microwave package, where each layer contacts an adjacent layer without an intervening metallic layer.
The following detailed description illustrates embodiments of the invention by way of example and not by way of limitation. It is contemplated that the invention has general application to embodiments of absorbing moisture in flexible microwave packages in industrial, commercial, and residential applications, such as, preheating industrial components and workpieces, sterilization and pasteurization processes, as well as home microwave food preparation.
As used herein, an element or step recited in the singular and preceded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
Embodiments of the present invention include a flexible microwave packaging that absorbs moisture that is generated during the microwave cooking process. For example, moisture containing foods tend to liberate some of that moisture into the package when heated in a microwave oven. Such moisture then wets the food item, making it soggy. Absorbing the moisture as it is generated in the package reduces or eliminates food items from getting soggy. Breaded or other food items stay crisp. The packaging is also capable of absorbing grease. This can be important for the preparation of fatty/greasy food items like bacon or French fries.
In one embodiment, the entire inner surface or most of the entire inner surface of the packaging has moisture-absorbent properties. Steam that has formed can be captured and bound in this manner, and thereby the condensation on both the inside of the microwave packaging and on the outside of the food is reduced. In this way, the outside of the food does not become soggy when it is heated.
In various embodiments, uniform package properties are used over the surface of the heat-sealable laminate from which the microwave packaging is formed, with regard to the absorption of moisture. Because the package does not use a susceptor, the moisture generated inside the package during heating is reduced. The residual moisture that still occurs is absorbed by the moisture-absorbent layer and thus does not impair the food. Accordingly, heating of the food product can be achieved without the food losing its crispiness.
Additionally, the absence of a susceptor layer also permits the microwave packaging described herein to be heated to a lower temperature as a whole. A susceptor that is exposed to microwave energy may heat up to temperatures of typically approximately 160° C. to approximately 180° C., whereas, in accordance with embodiments of the present invention, the heating process is predominately by the formation of steam to directly heat the food, which is limited to a temperature range of about 100° C. Accordingly, lower temperature and lower cost films may be used to construct the packaging described herein, which also are more flexible than films that can withstand higher temperatures.
The flexible, heat-sealable laminate according to embodiments of the present invention includes layers having a polymer base substance. In various embodiments, the laminate includes layers of paper or paperboard and can be processed similar to usual packaging films, and preferably has corresponding layer thicknesses and weights per area unit. The laminate can be used in packaging and bag-shaping machines in which the laminate is drawn off a roll to form individual packaging units, for example, side-fold bags and other packages.
In various embodiments, front panel 102 includes an inner perforated sealant film 114. Moisture generated in an interior volume 116 of package 100 penetrates through perforated sealant film 114. In the exemplary embodiment, perforated sealant film 114 comprises polyethylene (PE), polypropylene (PP), copolymers of PE or PP or combinations thereof. The thickness of perforated sealant film 114 ranges from approximately 10.0 micrometers (μm) to approximately 200.0 μm. In various embodiments, perforated sealant film 114 is preferable in the range of approximately 30.0 μm to approximately 100.0 μm.
The moisture is absorbed by an absorbent layer 118. In the exemplary embodiment, absorbent layer 118 comprises a nonwoven material having a water absorption capacity of approximately 100.0 to approximately 5,000 milliliters per meter squared (ml/m2). In various embodiments, the nonwoven material includes hydrophilic properties, additives and/or coatings and comprises airlaid or spunbond nonwovens and/or super absorbent materials such as, but not limited to, super absorbent polymers (SAP). Absorbent layer 118 is at least partially laminated against perforated sealant film 114.
In the exemplary embodiment, moisture-absorbent layer 118 is formed from a nonwoven material, such as a spunbond or an airlaid nonwoven, and at least a portion of the fibers of the nonwoven are hydrophilic, and/or moisture-absorbent particles are embedded between the fibers. The moisture-absorbent layer preferably has a moisture-absorbent material including at least one of silica gel, calcium oxide, activated clay, and super-absorbent polymer or mixtures of at least two of these substances. Super-absorbent polymers may include polyarylate salts, carboxymethyl celluloses, and starch polymers, among others. In the case of a moisture-absorbent nonwoven, an increased accommodation capacity for moisture can also be achieved, additionally or alternatively, by means of a wetting agent that is mixed into the polymer when forming the nonwoven, or applied as a coating of the fibers. An embodiment in which the nonwoven is disposed, proceeding from the inside of the microwave packaging, behind a heat-sealable inner layer that permits the penetration of moisture. The fibers of the nonwoven allow sufficient laminate adhesion with the adjacent layers and also make available a volume for the moisture-absorbent particles. The nonwoven is at least particularly open-pored and also allows significant expansion of the absorbent particles due to the absorption of moisture.
Back panel 104 includes a first sealing edge 124 and an opposite second sealing edge 126 and is formed of a perforated layer 128 adjacent interior 116, an outer layer 130 adjacent an exterior of flexible package 100, and an absorbent layer 132 extending from first sealing edge 124 to second sealing edge 126 between perforated layer 128 and outer layer 130. In the exemplary embodiment, absorbent layer 132 comprises a layer of spunbond or airlaid nonwoven material. In one embodiment, front panel 102 and back panel 104 comprises a single panel that is includes a fold along one edge and sealed along opposite edges, such as edges 108 and 110, and edges 109 and 111.
In various embodiments, the laminate structure of front panel 102 and back panel 104 is formed into microwave cooking or heating package 100 having a steam release feature 136. In one embodiment, steam release feature 136 comprises a punched hole 138. In other embodiments, steam release feature 136 comprises a steam venting label or valve 140. Due to the flexible nature of package 100 formed of the laminate structure, convenience features, such as, steam venting label or valve 140, easy opening features, and reclosable features are more easily implemented in package 100.
In the exemplary embodiment, a susceptor is not used to increase the temperature generated in package 100 and specifically in the areas adjacent where a susceptor would be located. The absence of a susceptor limits the temperature generated in package 100, which tends to limit the generation of moisture and liquefied lipids within package 100 during heating. Elimination of the susceptor also permits using less costly and more flexible film materials in the construction of package 100.
Tie layer 301 is extrusion coated onto absorbent layer 118. Printed PET film 302 is glue laminated against the coated absorbent layer 118. Sealant film 114 is extruded and perforated and then the laminated and coated absorbent layer is glue laminated against perforated sealant film 114 to form front panel 102 and/or back panel 104. The perforation of the sealant film can be applied directly inline with the lamination against the coated absorbent layer.
The PE film of tie layer 301 is used to improve an appearance of the flexible package by smoothing the rough surface of the spunbond nonwoven material of absorbent layer 118.
Although described herein with reference to front panel 102 and/or back panel 104 in
The above-described embodiments of a system and apparatus for moisture absorbent flexible microwave packaging provides a cost-effective and reliable means for improving of food quality due to a reduction of surface sogginess of food items and enhancing the microwave preparation of ready-to-eat meals. More specifically, the system and apparatus described herein facilitate a moisture controlled microwave heating and/or cooking environment inside a microwavable package having flexible sides. As a result, the system and apparatus described herein facilitate a heating preparation of food items in a cost-effective and reliable manner.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
