Vented susceptor structure

TECHNICAL FIELD

0001This disclosure relates to various microwave energy interactive structures, packages, apparatuses, or constructs for heating, browning, and/or crisping a food item in a microwave oven.

BACKGROUND

0002Microwave ovens provide a convenient means for heating a variety of food items, including sandwiches and other bread and/or dough-based products such as pizzas and pies. However, microwave ovens tend to cook such items unevenly and are unable to achieve the desired balance of thorough heating and a browned, crisp crust. As such, there is a continuing need for improved materials, packages, and other constructs that provide the desired degree of heating, browning, and/or crisping of various food items in a microwave oven.

0003<patcit id="pcit0001" dnum="US2004234653A1"><text>US 2004/234653 A1</text></patcit> discloses a method of using a microwave heating construct, comprising: placing a food item on the construct, the food item having a surface to be browned and/or crisped, wherein the construct comprises a panel, the panel comprises microwave energy interactive material operative for converting at least a portion of impinging microwave energy into thermal energy, the panel includes an aperture, and the placing of the food item on the construct comprises placing the food item on the panel so that the surface of the food item is adjacent to the aperture.

SUMMARY

0004The invention is a method according to claim 1.

0005This disclosure is directed generally to various constructs and methods for heating, browning, and/or crisping a food item in a microwave oven. In accordance with at least some embodiments of the disclosure, the various constructs generally include at least two sections or panels that are partially joined to one another to define a gap or unjoined area between the panels. At least one panel, for example, the panel intended for contact with the food item, includes one or more apertures that communicate with the unjoined area. The apertures cooperate with the unjoined area to assist with the transport or venting of moisture away from the food item to enhance the browning and/or crisping of the food item. Further, one or both panels include a susceptor or susceptor layer, i.e., a thin layer of microwave energy interactive material (generally less than about 100 angstroms in thickness, for example, from about 60 to about 100 angstroms in thickness, and having an optical density of from about 0.15 to about 0.35, for example, about 0.17 to about 0.28) that tends to absorb at least a portion of impinging microwave energy and convert it to thermal energy (i.e., heat). The thermal energy then can be transferred to the food item to heat, brown, and/or crisp the food item.

0006In some examples, the arrangement of susceptors and/or apertures may be used to simulate the appearance of food items prepared using other conventional heating apparatuses, for example, grills or skillets. In other examples, the arrangement of susceptors and/or apertures may be used to impart a logo, a graphic, product information, or any other indicia to the surface of the food item.

0007The apparatus or construct may be used to prepare various food items in a microwave oven, for example, sandwiches, savory or sweet pastries, breaded food items, or any other food item that desirably is heated, browned, and/or crisped. The construct may be formed at least partially from a disposable material, for example, paper or paperboard.

0008Additional aspects, features, and advantages of the present invention will become apparent from the following description and accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

0009The description refers to the accompanying drawings in which like reference numerals refer to like parts throughout the several views, and in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001"><b>FIG. 1A</b></figref> is a schematic top plan view of an exemplary construct for heating, browning, and/or crisping a food item in a microwave oven;</li><li><figref idref="f0001"><b>FIG. 1B</b></figref> is a schematic end elevation view of the construct of <figref idref="f0001"><b>FIG. 1A</b></figref><b>;</b></li><li><figref idref="f0001"><b>FIG. 1C</b></figref> is a schematic bottom plan view of the construct of <figref idref="f0001"><b>FIG. 1A</b></figref><b>;</b></li><li><figref idref="f0002"><b>FIGS. 1D</b> and <b>1E</b></figref> are schematic top and bottom plan views of an exemplary blank for forming the construct of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref>;</li><li><b>FIG. IF</b> is a schematic cross-sectional view of the blank of <figref idref="f0002"><b>FIG. 1E</b></figref> taken along a line <b>1F-1F;</b></li><li><figref idref="f0003"><b>FIGS. 1G-1I</b></figref> schematically illustrate an exemplary method for forming the construct of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref> from the blank of <figref idref="f0002"><b>FIGS. 1D-1F</b></figref><b>;</b></li><li><figref idref="f0004"><b>FIG. 2A</b></figref> is a schematic top plan view of an exemplary construct for heating, browning, and/or crisping a food item in a microwave oven;</li><li><figref idref="f0004"><b>FIG. 2B</b></figref> is a schematic end elevation view of the construct of <figref idref="f0004"><b>FIG. 2A</b></figref><b>;</b></li><li><figref idref="f0004"><b>FIG. 2C</b></figref> is a schematic bottom plan view of the construct of <figref idref="f0004"><b>FIG. 2A</b></figref><b>;</b></li><li><figref idref="f0005"><b>FIGS. 2D</b> and <b>2E</b></figref> are schematic top and bottom plan views of an exemplary blank for forming the construct of <figref idref="f0004"><b>FIGS. 2A-2C</b></figref><b>;</b></li><li><figref idref="f0005"><b>FIG. 2F</b></figref> is a schematic cross-sectional view of the blank of <figref idref="f0005"><b>FIG. 2E</b></figref> taken along a line <b>2F-2F;</b> and</li><li><figref idref="f0006"><b>FIGS. 2G-2I</b></figref> schematically illustrate an exemplary method for forming the construct of <figref idref="f0004"><b>FIGS. 2A-2C</b></figref> from the blank of <figref idref="f0005"><b>FIGS. 2D-2F</b></figref><b>.</b></li></ul>

DESCRIPTION

0010The present invention may be illustrated further by referring to the figures. For purposes of simplicity, like numerals may be used to describe like features. It will be understood that where a plurality of similar features are depicted, not all of such features necessarily are labeled on each figure. It also will be understood that various components used to form the microwave energy interactive structures may be interchanged. Thus, while only certain combinations are illustrated herein, numerous other combinations and configurations are contemplated by this disclosure.

0011<figref idref="f0001"><b>FIGS. 1A-1C</b></figref> schematically illustrate an exemplary microwave heating construct or apparatus <b>100</b> (e.g., a tray or card) for heating, browning, and/or crisping a food item <b>F</b> (shown schematically with dashed lines) in a microwave oven. <figref idref="f0001"><b>FIG. 1A</b></figref> schematically illustrates a top plan view of a first side (e.g., top) of the construct <b>100,</b><figref idref="f0001"><b>FIG. 1B</b></figref> schematically illustrates an end elevation view of the construct <b>100</b> of <figref idref="f0001"><b>FIG. 1A,</b> and <b>FIG. 1C</b></figref> schematically illustrates a top plan view of a second side (e.g., bottom) of the construct <b>100.</b>

0012The construct <b>100</b> has a generally rectangular shape suitable for receiving a somewhat elongate food item or a plurality of smaller food items thereon, for example, a French bread pizza, a filled pastry product, a breaded meat product, a calzone, a Stromboli, or any other suitable food item. However, the construct <b>100</b> may have any suitable shape needed or desired to prepare a particular food item (or items).

0013The construct <b>100</b> and its various features or components generally have a first dimension, for example, a length, extending in a first direction, for example, a longitudinal direction, <b>D1,</b> and a second dimension, for example, a width, extending in a second direction, for example, a transverse direction, <b>D2</b>. It will be understood that such designations are made only for convenience and do not necessarily refer to or limit the manner in which the construct is manufactured. In some embodiments, the construct <b>100</b> may be symmetric or nearly symmetric about a transverse centerline <b>CT</b> and/or along a longitudinal centerline <b>CL.</b>

0014The construct <b>100</b> includes a first panel <b>102</b> and a second panel <b>104</b> partially joined to one another to create a multilayer structure that includes an unjoined area or gap <b>106</b> between the panels <b>102, 104,</b> as shown in <figref idref="f0001"><b>FIG. 1B</b></figref><b>.</b> It will be understood that the size of the gap is exaggerated for illustrative purposes in <figref idref="f0001"><b>FIG. 1B</b></figref> and that the actual space or distance between the two panels <b>102, 104</b> may be very small, such that the panels <b>102, 104</b> may be at least partially contacting one another.

0015The first panel <b>102</b> and the second panel <b>104</b> may be joined to one another adhesively or otherwise along an attachment area <b>108 (FIG. IB),</b> for example, along a portion of the peripheral margin of the construct <b>100,</b> or in any other suitable area of the construct <b>100.</b> In this example, the construct <b>100</b> includes a single, substantially continuous attachment area <b>108,</b> although other embodiments may include two or more attachment areas. At least a portion of the peripheral margin may remain unattached, for example, at least a portion of one or both ends <b>110</b> of the construct <b>100,</b> as shown in <figref idref="f0001"><b>FIG. 1B</b></figref><b>.</b>

0016One or both panels <b>102, 104</b> may include one or more venting apertures <b>112</b> that extend through the thickness of the respective panel <b>102, 104</b> to assist with the transport of moisture and other vapors away from the food item <b>F</b> and to further enhance browning and/or crisping. In this example, panel <b>102</b> includes a plurality of substantially circular apertures <b>112</b> arranged in rows extending substantially in the first direction <b>D1.</b> A first row of apertures <b>112</b> lies substantially along the longitudinal centerline <b>CL,</b> while second and third rows of apertures <b>112</b> lie between the first row and respective longitudinal edges <b>114</b> of the construct <b>100.</b> In this example, the first row includes five apertures and the second and third rows each include four apertures. However, other shapes, numbers, and configurations of apertures may be used.

0017Each panel <b>102, 104</b> includes a microwave energy interactive element <b>116a, 116b,</b> for example, a susceptor or susceptor layer (shown schematically with stippling in <figref idref="f0001"><b>FIGS. 1A</b> and <b>1C</b></figref>). Each susceptor layer <b>116a, 116b</b> is operative for converting at least a portion of impinging microwave energy into thermal energy, which then can be transferred to the surface of the food item <b>F.</b> In this example, each susceptor layer <b>116a, 116b</b> extends substantially to the various peripheral edges of the construct. However, it is contemplated that the susceptor layer <b>116a, 116b</b> may be used in only a portion of the construct <b>100.</b>

0018As will be apparent from the figures, in all areas of the construct <b>100</b> except where an aperture <b>112</b> is present, there are two susceptor layers <b>116a, 116b</b> in a superposed arrangement with one another. Further, except where the panels <b>102, 104</b> are adjoined to one another along the attachment area <b>108,</b> there is an unjoined area that defines a void, space, or gap <b>106</b> between the panels <b>102, 104.</b> The present inventor has discovered that a construct including two superposed susceptor layers <b>116a, 116b</b> supported on partially unjoined panels <b>102, 104</b> results in superior heating, browning, and/or crisping when compared with a construct including two superposed susceptors on panels that are substantially joined to one another. While not wishing to be bound by theory, it is believed that the apertures <b>112</b> work in concert with the unjoined area or space <b>106</b> between the panels <b>102, 104</b> to provide a conduit for transporting moisture away from the food item, thereby allowing the food item to be browned and/or crisped more effectively.

0019To use the construct <b>100</b> according to one exemplary method, the food item <b>F</b> may be placed on a food-contacting surface <b>118</b> of the construct <b>100,</b> in this example, such that the food item <b>F</b> is seated on at least a portion of the first panel <b>102.</b> Upon sufficient exposure to microwave energy, the susceptors <b>116a, 116b</b> convert at least a portion of the impinging microwave energy into thermal energy, which then may brown and/or crisp the surface of the food item. Browning and/or crisping may be facilitated further by the apertures <b>110,</b> void <b>106,</b> and unjoined peripheral margin of panels <b>102, 104</b> along the end(s) <b>110</b> of the construct <b>100,</b> which collectively allow any excess moisture to be carried away from the food item <b>F.</b>

0020It will be recognized that during use, the weight of the food item may urge a portion of the first panel <b>102</b> towards the second panel <b>104,</b> such that a portion of the first panel <b>102</b> is brought into contact with the second panel <b>104.</b> In such areas, there may be little or no gap <b>106</b> between the panels <b>102, 104.</b> However, the present inventor has recognized that paper-based materials (e.g., paper and paperboard) have a tendency to curl in the presence of moisture, and while not wishing to be bound by theory, it is believed that as the food item heats and the moisture level of the panels <b>102, 104</b> changes, the panels <b>102, 104</b> may tend to curl slightly towards or away from each other. As a result, in the areas where the first panel <b>102</b> is not pressing against the second panel <b>104,</b> some space, even if small, may remain between the panels <b>102, 104.</b> Such areas are believed to provide a sufficient pathway for the movement of moisture away from the food item.

0021Further, even where the space between panels <b>102, 104</b> is eliminated, moisture from the food item may still be carried away from the food item to assist with browning and/or crisping. Some of such moisture may be adsorbed onto the interior sides of panels <b>102, 104,</b> and/or may be absorbed into the material (e.g., fibers) forming the panels <b>102, 104.</b> Other possibilities are contemplated.

0022<figref idref="f0002"><b>FIGS. 1D</b> and <b>1E</b></figref> schematically depict opposite sides a blank <b>120</b> for forming the construct of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref><b>. FIG. ID</b> schematically illustrates a side (e.g., a first side) of the blank <b>120</b> that forms an interior of the construct <b>100,</b> while <figref idref="f0002"><b>FIG. 1E</b></figref> schematically illustrates a side (e.g., a second side) of the blank <b>120</b> that forms exterior side of the construct <b>100.</b>

0023The blank <b>120</b> and its various features generally have a first dimension, for example, a length, extending in a first direction, for example, a longitudinal direction, <b>D1,</b> and a second dimension, for example, a width, extending in a second direction, for example, a transverse direction, <b>D2</b>. It will be understood that such designations are made only for convenience and do not necessarily refer to or limit the manner in which the blank is manufactured or erected into a construct. In some embodiments, the blank <b>120</b> may include some features that are symmetric or nearly symmetric about a transverse centerline <b>CT</b> and/or along a longitudinal centerline <b>CL.</b>

0024The blank <b>120</b> includes a pair of panels <b>102, 104</b> foldably joined to one another along a longitudinal line of disruption <b>122,</b> for example, a fold line, score line, or the like, extending substantially along the longitudinal centerline <b>CL</b> of the blank <b>120.</b> Alternatively, the longitudinal line of disruption <b>122</b> may be spaced slightly from the longitudinal centerline <b>CL</b> in a manner that assists with the formation of a gap or void <b>106</b> between the panels <b>102, 104.</b> In other embodiments, the blank may include additional panels for forming a construct with side walls that define a gap between the panels. Such side walls may be gusseted if desired.

0025As shown in <b>FIG. ID,</b> the opposite marginal areas of panels <b>102, 104</b> (shown with dashed lines) serve as attachment or glue areas <b>108</b> for joining the panels <b>102, 104</b> to one another. However, the attachment area(s) may have any other suitable location. A plurality of apertures <b>112</b> extend through the thickness of panel <b>102.</b>

0026As shown in schematic cross-sectional view in <figref idref="f0002"><b>FIG. 1F</b></figref><b>,</b> each panel <b>102, 104</b> generally may comprise a plurality of adjoined layers. Each panel <b>102, 104</b> may comprise substantially the same arrangement of layers, for example, where the panels <b>102, 104</b> are formed from a single sheet of material, or may comprise different arrangements of layers, for example, where the construct <b>100</b> is formed from separate panels <b>102, 104.</b> The number, type, and arrangement of layers in each panel may vary depending on the heating, browning, and/or crisping needs for a particular application. Thus, numerous possibilities are contemplated.

0027In the illustrated embodiment, each panel <b>102, 104</b> includes a layer of microwave energy interactive material <b>116</b> operative as a susceptor (i.e., susceptors or susceptor layers <b>116a, 116b</b>) supported on a substantially microwave energy transparent material <b>124,</b> for example, a polymer film, to form a susceptor film <b>126.</b> The layer of microwave energy interactive material <b>116</b> may be joined to a support layer <b>128</b> (e.g., paper or paperboard) using an adhesive or other suitable material (not shown). Apertures <b>112</b> extend through the thickness of panel <b>102.</b>

0028As show schematically in <figref idref="f0003"><b>FIGS. 1G-1I</b></figref><b>,</b> to form the blank <b>120</b> into the construct <b>100</b> according to one exemplary method an adhesive material <b>130</b> (shown schematically with cross-hatching) may be applied to the attachment area <b>108</b> (<figref idref="f0003"><b>FIG. 1G</b></figref>) of one or both panels <b>102, 104,</b> folding panel <b>102</b> towards panel <b>104</b> along line of disruption <b>122</b> (<figref idref="f0003"><b>FIG. 1H</b></figref>), and bringing the peripheral edges of panels <b>102, 104</b> into alignment with one another (<figref idref="f0003"><b>FIG 1I</b></figref>) to join the panels <b>102, 104</b> to one another. However, numerous other methods of forming the construct <b>100</b> may be used.

0029<figref idref="f0004 f0005 f0006"><b>FIGS. 2A-2I</b></figref> schematically depict an exemplary variation of the microwave heating apparatus or construct <b>100</b> of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref> and blank <b>120</b> of <figref idref="f0002"><b>FIGS. 1D-1F</b></figref> for forming the apparatus of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref><b>.</b> The apparatus <b>200</b> and blank <b>220</b> include features that are similar to the apparatus <b>100</b> and blank <b>120</b> shown in <figref idref="f0001 f0002"><b>FIGS. 1A-1F</b></figref><b>,</b> except for variations noted and variations that will be understood by those of skill in the art. An exemplary method of forming the construct <b>200</b> from the blank <b>220</b> is illustrated schematically in <figref idref="f0006"><b>FIGS. 2G-2I</b></figref><b>.</b> For simplicity, the reference numerals of similar features are preceded in the figures with a <b>"2"</b> instead of a "<b>1</b>".

0030In this example, the construct <b>200</b> has a generally square shape with rounded corners suitable for receiving a somewhat square and/or rounded food item or a plurality of smaller food items thereon, for example, a pizza, an open faced sandwich, a filled pastry product, a breaded meat product, a calzone, a Stromboli, or any other suitable food item. However, numerous other shapes are contemplated.

0031Further, in this example, the apertures <b>212</b> comprise a plurality of elongate cutouts or slots extending in a direction oblique to the first direction <b>D1</b> and the second direction <b>D2.</b> More particularly, the apertures <b>212</b> are aligned in a direction substantially parallel to a first diagonal centerline <b>CD1</b> and in a direction substantially perpendicular to a second diagonal centerline <b>CD2.</b> In this example, the apertures are arranged in two groups on opposite sides of the second diagonal centerline <b>CD2.</b> However, any suitable shape, size, orientation, and arrangement of apertures may be used for a particular heating application. For example, in some embodiments, the apertures may have rounded corners. Numerous other possibilities are contemplated.

0032The construct <b>200</b> may be formed in the manner described in connection with <figref idref="f0003"><b>FIGS. 1G-1I</b></figref><b>,</b> as shown schematically in <figref idref="f0006"><b>FIGS. 2G-2I</b></figref><b>.</b>

0033Upon sufficient exposure to microwave energy, the susceptors <b>216a, 216b</b> convert at least a portion of the impinging microwave energy into thermal energy, which then may brown and/or crisp the surface of the food item. Less heat may be generated in the areas including the apertures <b>212,</b> since only susceptor <b>216b</b> is present, while more heat may be generated in the remaining areas where both susceptors <b>216a, 216b</b> are present. As a result, the food item may be browned and/or crisped somewhat less in the areas adjacent to the apertures <b>212.</b> The overall pattern of browning and/or crisping may resemble grill marks, such that the lighter and darker areas resemble the markings that may be obtained by heating a food item on a grill. Browning and/or crisping may be facilitated further by the transport of moisture away from the food item <b>F</b> via apertures <b>212,</b> the unjoined area or gap <b>206</b> between the panels <b>202, 204,</b> and the open end(s) <b>210</b> of the construct <b>200.</b>

0034In one particular example, the food item <b>F</b> may be a sandwich that has been separated into two sections, each including a piece of bread and one or more toppings in an "open face" configuration. After heating, the components of the sandwich may be stacked on top of one another in a facing relationship to form a double faced sandwich. In another example, both the bread and the "filling" of a sandwich may be desirably browned and/or crisped. The filling, for example, a breaded meat item, may be placed on one part of the construct, while the bread may be placed on the other, for example. If desired, the user may be instructed to invert or "flip" one or both items during heating to brown and/or crisp the opposite side of the respective item. Additionally or alternatively, where the sandwich includes two pieces of bread (i.e., where the sandwich is a double faced sandwich), the user may be instructed to replace the browned and/or crisped bread with the other piece, so that both pieces may be browned and/or crisped. Countless other possibilities are contemplated.

0035Numerous other microwave heating constructs are encompassed by the disclosure. Any of such constructs may be formed from various materials, provided that the materials are substantially resistant to softening, scorching, combusting, or degrading at typical microwave oven heating temperatures, for example, at from about 250°F to about 425°F. The materials may include microwave energy interactive materials, for example, those used to form susceptors (e.g., susceptors or susceptor layers <b>116a, 116b, 216a, 216b</b>) and other microwave energy interactive elements, and microwave energy transparent or inactive materials, for example, those used to form the remainder of the construct.

0036The microwave energy interactive material may be an electroconductive or semiconductive material, for example, a vacuum deposited metal or metal alloy, or a metallic ink, an organic ink, an inorganic ink, a metallic paste, an organic paste, an inorganic paste, or any combination thereof. Examples of metals and metal alloys that may be suitable include, but are not limited to, aluminum, chromium, copper, inconel alloys (nickel-chromium-molybdenum alloy with niobium), iron, magnesium, nickel, stainless steel, tin, titanium, tungsten, and any combination or alloy thereof.

0037Alternatively, the microwave energy interactive material may comprise a metal oxide, for example, oxides of aluminum, iron, and tin, optionally used in conjunction with an electrically conductive material. Another metal oxide that may be suitable is indium tin oxide (ITO). ITO has a more uniform crystal structure and, therefore, is clear at most coating thicknesses.

0038Alternatively still, the microwave energy interactive material may comprise a suitable electroconductive, semiconductive, or non-conductive artificial dielectric or ferroelectric. Artificial dielectrics comprise conductive, subdivided material in a polymeric or other suitable matrix or binder, and may include flakes of an electroconductive metal, for example, aluminum.

0039In other embodiments, the microwave energy interactive material may be carbon-based, for example, as disclosed in <patcit id="pcit0002" dnum="US4943456A"><text>U.S. Patent Nos. 4,943,456</text></patcit>, <patcit id="pcit0003" dnum="US5002826A"><text>5,002,826</text></patcit>, <patcit id="pcit0004" dnum="US5118747A"><text>5,118,747</text></patcit>, and <patcit id="pcit0005" dnum="US5410135A"><text>5,410,135</text></patcit>.

0040In still other embodiments, the microwave energy interactive material may interact with the magnetic portion of the electromagnetic energy in the microwave oven. Correctly chosen materials of this type can self-limit based on the loss of interaction when the Curie temperature of the material is reached. An example of such an interactive coating is described in <patcit id="pcit0006" dnum="US4283427A"><text>U.S. Patent No. 4,283,427</text></patcit>.

0041While susceptors are described in detail herein, it will be appreciated that the construct may include other microwave energy interactive elements. By way of example, the construct may include a foil or high optical density evaporated material having a thickness sufficient to reflect a substantial portion of impinging microwave energy. Such elements typically are formed from a conductive, reflective metal or metal alloy, for example, aluminum, copper, or stainless steel, in the form of a solid "patch" generally having a thickness of from about 0.000285 inches (0.007239 mm) to about 0.005 inches (0.127 mm), for example, from about 0.0003 inches (0.00762 mm) to about 0.003 inches (0.0762 mm). Other such elements may have a thickness of from about 0.00035 inches (0.00889 mm) to about 0.002 inches (0.0508 mm), for example, 0.0016 inches (0.04064 mm).

0042In some cases, microwave energy reflecting (or reflective) elements may be used as shielding elements where the food item is prone to scorching or drying out during heating. In other cases, smaller microwave energy reflecting elements may be used to diffuse or lessen the intensity of microwave energy. One example of a material utilizing such microwave energy reflecting elements is commercially available from Graphic Packaging International, Inc. (Marietta, GA) under the trade name MicroRite® packaging material. In other examples, a plurality of microwave energy reflecting elements may be arranged to form a microwave energy distributing element to direct microwave energy to specific areas of the food item. If desired, the loops may be of a length that causes microwave energy to resonate, thereby enhancing the distribution effect. Microwave energy distributing elements are described in <patcit id="pcit0007" dnum="US6204492B"><text>U.S. Patent Nos. 6,204,492</text></patcit>, <patcit id="pcit0008" dnum="US6433322B"><text>6,433,322</text></patcit>, <patcit id="pcit0009" dnum="US6552315B"><text>6,552,315</text></patcit>, and <patcit id="pcit0010" dnum="US6677563B"><text>6,677,563</text></patcit>.

0043In still another example, the construct may include a microwave energy interactive insulating material. Examples of such materials are provided in <patcit id="pcit0011" dnum="US7019271B"><text>U.S. Patent No. 7,019,271</text></patcit>, <patcit id="pcit0012" dnum="US7351942B"><text>U.S. Patent No. 7,351,942</text></patcit>, and <patcit id="pcit0013" dnum="US20080078759A1" dnum-type="L"><text>U.S. Patent Application Publication No. 2008/0078759 A1, published April 3, 2008</text></patcit>.

0044As discussed above, any of the numerous microwave energy interactive elements (e.g., susceptors, foils, etc.) described herein or contemplated hereby may be substantially continuous, that is, without substantial breaks or interruptions, or may be discontinuous, for example, by including one or more breaks or apertures that transmit microwave energy. The breaks or apertures may extend through the entire structure, or only through one or more layers. The number, shape, size, and positioning of such breaks or apertures may vary for a particular application depending on the type of construct being formed, the food item to be heated therein or thereon, the desired degree of heating, browning, and/or crisping, whether direct exposure to microwave energy is needed or desired to attain uniform heating of the food item, the need for regulating the change in temperature of the food item through direct heating, and whether and to what extent there is a need for venting.

0045By way of illustration, a microwave energy interactive element may include one or more transparent areas to effect dielectric heating of the food item. However, where the microwave energy interactive element comprises a susceptor, such apertures decrease the total microwave energy interactive area, and therefore, decrease the amount of microwave energy interactive material available for heating, browning, and/or crisping the surface of the food item. Thus, the relative amounts of microwave energy interactive areas and microwave energy transparent areas must be balanced to attain the desired overall heating characteristics for the particular food item.

0046In some embodiments, one or more portions of the susceptor may be designed to be microwave energy inactive to ensure that the microwave energy is focused efficiently on the areas to be heated, browned, and/or crisped, rather than being lost to portions of the food item not intended to be browned and/or crisped or to the heating environment.

0047In other embodiments, it may be beneficial to create one or more discontinuities or inactive regions to prevent overheating or charring of the food item and/or the construct including the susceptor. By way of example, the susceptor may incorporate one or more "fuse" elements that limit the propagation of cracks in the susceptor structure, and thereby control overheating, in areas of the susceptor structure where heat transfer to the food is low and the susceptor might tend to become too hot. The size and shape of the fuses may be varied as needed. Examples of susceptors including such fuses are provided, for example, in <patcit id="pcit0014" dnum="US5412187A"><text>U.S. Patent No. 5,412,187</text></patcit>, <patcit id="pcit0015" dnum="US5530231A"><text>U.S. Patent No. 5,530,231</text></patcit>, U.S. Patent Application Publication No. <patcit id="pcit0016" dnum="US20080035634A1"><text>US 2008/0035634A1, published February 14, 2008</text></patcit>, and <patcit id="pcit0017" dnum="WO2007127371A"><text>PCT Application Publication No. WO 2007/127371, published November 8, 2007</text></patcit>.

0048In the case of a susceptor, any of such discontinuities or apertures may comprise a physical aperture or void (e.g., apertures <b>112, 212</b>) in one or more layers or materials used to form the structure or construct. A physical aperture also provides a venting function to allow steam or other vapors or liquids released from the food item to be carried away from the food item.

0049As stated above, the microwave energy interactive element may be supported on a microwave inactive or transparent substrate <b>124, 224</b> (<figref idref="f0002"><b>FIGS. 1F</b></figref> and <figref idref="f0005"><b>2F</b></figref>), for example, a polymer film or other suitable polymeric material, for ease of handling and/or to prevent contact between the microwave energy interactive material and the food item. The outermost surface of the polymer film may define at least a portion of the food-contacting surface of the package (e.g., surface <b>118, 218</b> of respective polymer film <b>124, 224</b>)<b>.</b> Examples of polymer films that may be suitable include, but are not limited to, polyolefins, polyesters, polyamides, polyimides, polysulfones, polyether ketones, cellophanes, or any combination thereof. In one particular example, the polymer film comprises polyethylene terephthalate. The thickness of the film generally may be from about 35 gauge to about 10 mil. In each of various examples, the thickness of the film may be from about 40 to about 80 gauge, from about 45 to about 50 gauge, about 48 gauge, or any other suitable thickness. Other non-conducting substrate materials such as paper and paper laminates, metal oxides, silicates, cellulosics, or any combination thereof, also may be used.

0050If desired, the polymer film may undergo one or more treatments to modify the surface prior to depositing the microwave energy interactive material onto the polymer film. By way of example, and not limitation, the polymer film may undergo a plasma treatment to modify the roughness of the surface of the polymer film. While not wishing to be bound by theory, it is believed that such surface treatments may provide a more uniform surface for receiving the microwave energy interactive material, which in turn, may increase the heat flux and maximum temperature of the resulting susceptor structure. Such treatments are discussed in <patcit id="pcit0018" dnum="US70957810A" dnum-type="L"><text>U.S. Patent Application No. 12/709,578, filed February 22, 2010</text></patcit>.

0051The microwave energy interactive material may be applied to the substrate in any suitable manner, and in some instances, the microwave energy interactive material is printed on, extruded onto, sputtered onto, evaporated on, or laminated to the substrate. The microwave energy interactive material may be applied to the substrate in any pattern, and using any technique, to achieve the desired heating effect of the food item. For example, the microwave energy interactive material may be provided as a continuous or discontinuous layer or coating including circles, loops, hexagons, islands, squares, rectangles, octagons, and so forth.

0052Various materials may serve as the base material <b>128, 228</b> (<figref idref="f0002"><b>FIGS</b>. <b>1F</b></figref> and <figref idref="f0005"><b>2F</b></figref>) for the construct <b>100, 200</b>. For example, the construct may be formed at least partially from a polymer or polymeric material. As another example, all or a portion the construct may be formed from a paper or paperboard material. The paper may have a basis weight of from about 15 to about 60 lbs/ream (lb/3000 sq. ft., 15 lbs/ream = 24,41g/m², 60 lbs/ream = 97,66g/m²), for example, from about 20 to about 40 lbs/ream (32,55 g/m2 to about 65,10 g/m2). In another example, the paper may have a basis weight of about 25 lbs/ream (40,69 g/m²). The paperboard may have a basis weight of from about 60 to about 330 lbs/ream (97,66 to about 537,11 g/ m²), for example, from about 155 to about 265 lbs/ream (252,28 to about 431,32 g/m²). In one particular example, the paperboard may have a basis weight of about 175 lbs/ream (284,83 g/m²). The paperboard generally may have a thickness of from about 6 to about 30 mils (0.1524 to about 0.762 mm), for example, from about 14 to about 24 mils (0.3556 to about 0.6096 mm). In one particular example, the paperboard may have a thickness of about 16 mils (0.4064 mm). Any suitable paperboard may be used, for example, a solid bleached or solid unbleached sulfate board, such as SUS® board, commercially available from Graphic Packaging International.

0053The construct may be formed according to numerous processes known to those in the art, including using adhesive bonding, thermal bonding, ultrasonic bonding, mechanical stitching, or any other suitable process. Any of the various components used to form the construct may be provided as a sheet of material, a roll of material, or a die cut material in the shape of the package to be formed (e.g., a blank).

0054The disclosure may be understood further from the following examples, which are not intended to be limiting in any manner.

EXAMPLE 1

0055The heating, browning, and/or crisping of a commercially available frozen Stromboli product was compared using various apparatuses. A first apparatus was similar the apparatus of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref><b>.</b> A second apparatus was similar to the first apparatus, except that the first panel and the second panel were joined substantially continuously to one another, such that there was little or no gap between the panels.

0056Each Stromboli was heated on the respective apparatus for about 3 minutes in an 1100 W Panasonic microwave oven that included a turntable. After heating, the bottom of each Stromboli was examined. The Stromboli heated on the first apparatus was heated, browned, and crisped suitably, while the Stromboli heated on the second apparatus was not browned or crisped to the desired level.

EXAMPLE 2

0057The heating, browning, and/or crisping of a commercially available frozen Panini product was compared using various apparatuses. A first apparatus was similar the apparatus of <figref idref="f0004"><b>FIGS. 2A-2C</b></figref><b>.</b> A second apparatus was a microwave heating tray seated on a carton. A third apparatus was similar to the first apparatus, except that the first panel and the second panel were joined substantially continuously to one another, such that there was little or no gap between the panels. The third apparatus also was substantially octagonal in shape.

0058Each Panini was heated on the respective apparatus for about 3 minutes in an 1100 W Panasonic microwave oven that included a turntable. The Panini heated on the first apparatus was heated, browned, and crisped suitably, while the Paninis heated on the second and third apparatuses were not browned or crisped to the desired level.

EXAMPLE 3

0059The heating, browning, and/or crisping of a commercially available frozen flatbread pizza product was compared using various apparatuses. A first apparatus was similar the apparatus of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref><b>,</b> except the arrangement of apertures differed from the apparatus of <figref idref="f0001"><b>FIGS. 1A-1C</b></figref><b>.</b> Further, the apertures were formed manually by punching a die or other suitable implement into the food-contacting panel, thereby partially striking flap-like tabs from the panel. (Such tabs or protrusions may have extended somewhat into the gap, such that the tabs or protrusions may have assisted with maintaining a space between the panels.) A second apparatus was a single layer susceptor tray with side walls including apertures.

0060Each flatbread pizza was heated on the respective apparatus for about 2 minutes in an 1100 W Panasonic microwave oven that included a turntable. After heating, the bottom of each flatbread pizza was examined. The flatbread pizza heated on the first apparatus was heated, browned, and crisped suitably, while the flatbread pizza heated on the second apparatus was not browned or crisped to the desired level.

0061While the present invention is described herein in detail in relation to specific aspects and embodiments, it is to be understood that this detailed description is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the present invention and to set forth the best mode of practicing the invention known to the inventors at the time the invention was made. The detailed description set forth herein is illustrative only and is not intended, nor is to be construed, to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications, and equivalent arrangements of the present invention. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are used only for identification purposes to aid the reader's understanding of the various embodiments of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention unless specifically set forth in the claims. Joinder references (e.g., joined, attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily imply that two elements are connected directly and in fixed relation to each other. Further, various elements discussed with reference to the various embodiments may be interchanged to create entirely new embodiments coming within the scope of the present invention.