Abstract: A method and device for enhancing the heating of a surface layer of an article being heated by microwave energy is characterized by directing the energy through the surface layer into a main portion of the article in such a manner that the modes of the energy are in cut-off in the surface layer.

Abstract: A bag for carrying corn kernels for popping in a microwave oven. The bag has front, back, and gusseted side panels and carries a susceptor for receiving microwave energy and heating the corn for popping. In general, the bag is of the single gusset tube type with a V-shaped bottom. The bag has winged end constructions where the seals are entirely internal, in a linear zone or band that extends from side-to-side, (i.e. transversely of the bag length). The top seal is not as strong as the bottom seal, so as to permit top venting. In the winged construction the front and back panel centers are adhered together and gusset folds are secured to an adjacent front or back panel. Upon bag expansion the bag has an increased internal volume for its size, minimizes tilting and maximizes susceptor/oven floor contact and can be set upright on the bottom end winged construction. This bag structure provides for more complete popping and for a more pleasing pillow shape for the bag.

Abstract: A microwave heating package for containing a food item to be cooked in a microwave oven including a top wall, a bottom wall and a side wall. A microwave interactive layer is affixed to the bottom wall for converting microwave energy into heat. The side wall is scored to define a first end flap and a second end flap. Each end flap is partially separable from the remainder of the package along the scoring and is hingedly connected to the bottom wall such that the separable portion of each end flap is pivotable from a first unseparated position to a second position located underneath the bottom wall.

Abstract: The method of forming a microwaveable package, generally from a plurality of liners of material, and incorporating a heat-assist layer preferably intermediately of the liners of material, which said heat assist material comprising powdered carbon, that is originally applied to the inner surface of one of the intended liners, and in register at that location where the layer is desired within the formed microwave package. The material may be imprinted by a gravure or other roller application onto the inner surface of one of said liners of material, or adhesive applied or added onto that adhesive that laminates the liners together, in order to assure that proper and convenient registration of the layer within the laminate material, and provide for its location within the formed package preferably at a lower position where the food or other product is arranged, during microwaving, to attain that necessary heat assist desired from its addition.

Abstract: A bag for heating food products in a microwave oven and a blank for forming the bag are disclosed. The bag is formed of a dielectric substrate having a laminated layer including at least one microwave interactive patch. The microwave interactive patches are positioned to avoid overheating at creases and seams formed in the bag. At least one of the microwave interactive patches includes a heat sensitive fuse.

Abstract: A bag for popping popcorn in a microwave oven has substantially rectangular front and back face panels and gusseted side panels joining the opposite side edges thereof. Top and bottom ends of the bag are normally closed and sealed, but the top end may be opened to remove the contents of the bag. The gusseted side panels unfold during cooking to enlarge the interior volume of the bag, forming triangularly shaped corner flaps at the junctures of the side panels and the front and back panels, respectively. In conventional bags, the confronting surfaces between the triangularly shaped panels of the corner flaps move apart when the side panels unfold and the bag expands during cooking, forming pockets between the confronting surfaces in which food particles may become trapped. In the invention, spots of adhesive are placed between these confronting surfaces to hold them in contiguous relationship to one another and prevent the formation of pockets, thereby enhancing the yield of food cooked in the bag.

Abstract: An ovenable food package for holding a food product. The package has a base which is constructed and arranged such that at least one exterior gap is created between the base and the support surface of the oven (conventional or microwave) in which the package and food product are placed into to be cooked. The base is also constructed and arranged to create at least one interior gap between the food product and the base. A further ovenable food package is disclosed in which a lid is provided that is adapted to be removed and then replaced on top of the package to create a space between the food product and the lid. A food package including a base for the food product and a box containing the base and food product is also disclosed.

Abstract: A flexible, sealable container apparatus having a substantially pinch-bottomed configuration prior to expansion of the bag during cooking. The container apparatus includes substantially quadrilateral regions of adhesive. The shape and positioning of the quadrilateral regions, with diagonals substantially collinear to panel edges of the container apparatus, serves to articulate the container apparatus into a substantially rectangular-bottomed configuration during cooking, while improving the integrity of the bottom region seals against blowout and/or leakage.

Abstract: A microwave popcorn container for recreational use and a method of making and dispensing popcorn using the same. The microwave popcorn container has an outer casing substantially transparent to microwave radiation and resembles either a playball or novelty configuration having an interior space therein. When exposed to microwave radiation, corn kernels contained within the interior space of the outer casing burst into popcorn filling the outer casing. The microwave popcorn container may be used in a variety of recreational activities and when desired, popcorn can be dispensed therefrom and consumed.

Abstract: A container for popping popcorn in a microwave oven includes bottom, front, side rear and top walls which are generally rectilinear and define an interior space for containing the popcorn. The container is formed of a cardboard material, and the side walls are collapsible inwardly to permit the container to collapse when pressure is applied to its bottom and top walls and to expand to define the interior space when pressure is applied to the junction of the rear wall and one of said top and bottom walls and the junction of the front wall and the other of the top and bottom walls. A material which reflects microwaves is disposed on the bottom wall and on a strip at the lower edges of the front rear and side walls.

Abstract: A self-venting package adapted for microwave cooking having first and second package walls made from thermoplastic polymeric film where the second package wall is joined at a portion of its perimeter to the first package wall thus creating a product receiving chamber defined between the first and second walls. The chamber is adapted to receive a product to be heated and the package is sealed by at least one multilayered seal strip having a thermoplastic polymeric film construction that is placed between the first and second package walls at an edge of the package. The seal strip consists of a first outer layer, positioned adjacent to an inner surface of the first package wall and adapted to be sealed thereto, a second outer layer, positioned adjacent to an inner surface of the second package wall and adapted to be sealed thereto, and a tie layer disposed between the first and the second outer layers where the tie layer is peelably bonded to the first outer layer and the second outer layer.

Abstract: A package for use in microwave ovens is disclosed in its preferred form of a flexible, tubular bag (18) including expandable side walls (26) interconnected between bottom and top walls (20, 22), an openable end (28), and a permanent end wall (24). The side walls (26) include pleats (26a, 26b, 26c, 26d) which are folded in a collapsed condition of the bag (18) and expand due to internal expansion forces generated by the popping of kernels and the creation of water vapor. In a preferred form, the bag (18) is formed from a single layer of flexible, greaseproof paper of highly refined raw fibers of 100% chemical softwood pulp and having a basis weight in the order of 35 lb./ream. The single layer of paper forming the bag (18) provides greaseproof properties in storage, transportation, and cooking throughout the thickness of the paper to prevent wicking and leaking of grease or oil through the single layer.

Abstract: An expandable collapsed bag, preferably made of paper, suitable for cooking corn in a microwave oven. The bag of the invention has front and back panels and two side panels, each side panel having two or more gussets. These gussets permit relatively free upward movement of the corn and fuller expansion of the bag during cooking. In its collapsed configuration, the back panel is folded to expose a portion of each side panel that forms one gussets. The collapsed bag thereby forms strips extending along each side edge in which the bag is four layers thick. Since a conventionally folded, two gusseted bag has six layers along its edges, the reverse folded bag is thinner and, therefore, advantageous from handling, shipping and storage viewpoints.

Abstract: An improved container for transporting food and similar products is provided. The container employs one or more layers of a breathable material which is permeable to water vapor but repellent to liquid. By enclosing hot food in this container, moisture vapor from the food dissipates away from the food and avoids the soggy texture which often accompanies transported food. The container of the present invention has a wide range of possible applications, including everything from delivery of individual pizzas to large scale relocation of food for institutional purposes.

Abstract: The invention relates to a method for the sterilization of the inside layer of a packaging material, the packaging material being produced as a laminate with an inside layer of a transparent thermoplastic which is applied on a reflective material layer. The sterilizing energy includes high energy light flashes emitted from one or more flash units, the light flashes being caused to act on the inside of the packaging material for purposes of exterminating bacteria and microorganisms present on the surface. Because the light flashes emitted from the flash unit are reflected by the reflective layer, the surface layer of the layer will be influenced by both the direct and the reflecting photoenergy from the flash units, the sterilizing effect being thereby improved. Packaging material well-suited for sterilization according to the method is also disclosed.

Abstract: Composition comprising (a) susceptors having the capability of absorbing microwave energy, said susceptors comprising a particulate substrate substantially non-reflective of microwave energy and a coating capable of absorbing microwave energy, and (b) a matrix substantially non-reflective of microwave energy. Susceptors are typically particles having a thin-film coating thereon. The matrix typically comprises polymeric or ceramic materials that are stable at temperatures conventionally used in microwave cooking. The composition allows reuse of the susceptors, eliminates decline in heating rate, eliminates arcing, allows the heating rate to be controlled, allows overheating to be controlled, and allows formation of microwave heatable composite materials having very low metal content.

Abstract: Disclosed are vacuum-packed food packages (10) having enlarged head spaces (56) under high vacuum, which enable food products (58) to be retorted after sealing, with resulting improved flavor, color, texture, and/or nutrient retention. Easily removable press-on, pry-off closures (13) having movable insert disks (16) in an outer shell (14) are also disclosed. Pressing the shell upward to remove it from a container (11) first pries a protrusion (28) inside the shell over a snap rib (22) around the container, then moves the shell upward relative to the disk until the snap rib engages the edge of the disk and lifts the disk to break the seal. A tamper evidencing band (22), if included, is broken before the shell is pried off or the disk is lifted. Food packages which automatically open when heated in microwave ovens are also disclosed.

Abstract: Microwave cookware of flexible, transparent material displaying an expandable bottom and two opposing walls, one wall containing an aperture, the other opposing wall displaying an extension, the objective being to manually pull the extension through the aperture rendering the bag closed and, vented, leaving the extension as a handling vehicle.

Abstract: A piece of microwave-active tape which is odor-free and physiologically inert can be adhered to a food package and remains strongly adhered during cooking at temperatures of at least 200.degree. C. The tape has layers of microwave-active material and a pressure-sensitive adhesive which is a polymeric .alpha.-olefin that has been cured to afford a "Peel Value" of at least 5 N/dm and a "Shrink Back" at 220.degree. C. of less than 5%. The tape can have a flexible backing such as a low-adhesion carrier web which can be stripped off from a piece of the tape that has been applied to a microwave food package, or when the backing is heat-resistant, it can be left in place.

Abstract: A food package including a package body forming a food receiving cavity for storing and heating a food item in a microwave oven. Specifically, the package body includes a bottom panel and a top panel with side panels joining the bottom and top panel. An impedance matching element is provided on at least one of the panels for impedance matching microwave energy entering the package. The impedance matching element is preferably a contiguous film of thinly flaked material embedded in a dielectric binder which is sized and shaped with respect to the food to cause impedance matching to elevate the temperature of the food in predetermined areas dependent upon the size and spacing of the film without interacting with the microwave energy to produce heat. The film may also be shaped in the form of a convex lens to direct impedance matched microwave energy toward the food to elevate the temperature of the food in a predetermined area.

Abstract: A container for a viscous food product having a configuration which enables relatively uniform heating of the contents at an acceptable rate without scorching in a conventional microwave oven. The preferred container is made from an electrically nonconductive material having a generally ovate bottom wall and a side wall extending upward therefrom to an upper end portion. The side wall may have a substantially ovate cross-section over substantially its entire height. The ovate cross-section may have a width-to-depth ratio of approximately 2:1 over substantially its entire height. The upper end portion may convexly decrease in width proceeding upward on the container.

Abstract: A package for microwave heating of a sandwich product which normally contains a bread component and non bread components which are either inserted into the bread or deposited on the bread. The non bread components, such as meats, chicken, fish, cheese, vegetables, sauces and the like are placed into a separate container and this non bread component container and the naked bread component are simultaneously contained within a microwave heating package. Microwave suseptor material surrounds at least portions of the bread component for crisping the bread to give it a good baked quality. The non bread component container may first be removed from the package so that the bread component and non bread components may be microwaved separately.

Abstract: A microwave-reflective device and method for enhancing microwave heating of food items. The microwave-reflective device comprises an upstanding, microwave-reflective wall. During cooking, the microwave-reflective device is maintained about the periphery of the food item, while the space inward and above the wall may be maintained free of obstructions to microwave radiation. A susceptor film may be employed beneath the food item during heating.

Abstract: A novel insert useful in a microwavable food container comprising a metallized layer of heat susceptor thickness or a plastic layer, having openings which are in a position to be adjacent to food in said container, a layer of absorbent material comprising fibers, and a substrate layer which is stable to microwave heating conditions. The invention also is directed towards other inserts useful in microwavable food containers comprising fibers which are capable of spontaneously transporting water or n-decane on the surface thereof.

Abstract: A conductive structure for use in microwave food packaging which adapts itself to heat food articles in a safer, more uniform manner is disclosed. The structure includes a conductive layer disposed on a non-conductive substrate. Provision in the structure's conductive layer of fuse links and base areas causes microwave induced currents to be channeled through the fuse links, resulting in a controlled heating. When over-exposed to microwave energy, fuses break more readily than the conductive base areas resulting in less absorption of microwave energy in the area of fuse breaks than in other regions where fuses do not break. In this way the fused microwave conductive structure compensates for the uneven microwave field within a microwave oven and at the same time provides a safer conductive structure less likely to overheat.

Abstract: A laminate for use in microwave cooking which includes a susceptor formed by depositing a thin layer of microwave-interactive material on a plastic base sheet, and then extrusion bonding that susceptor to a plastic coated paper sheet, without the use of an adhesive.

Abstract: A susceptor for use in the microwave cooking of food, includes a first plastic film, a second plastic film, and a semi-liquid lossy material disposed intermediate the first and second films. The lossy material includes glycerine, sucrose ester, and chloride salt, 25 grams of the lossy material in a 50 ml. glass beaker being heatable to at least 200.degree. C. within 40 seconds by 900 watts of microwave energy in a 1.1 cu. ft. oven. Preferably a layer of paper is sandwiched between the first and second films, the lossy material being absorbed on the paper layer. The susceptor is preferably biodegradable and edible. A method of microwave cooking includes the steps of providing an assembly of such a susceptor and the food to be microwave cooked, cooking the food in intimate contact with the susceptor in a microwave oven, and separating the microwave cooked food from the susceptor.

Abstract: A composite material suitable for use as a microwave heating wrapper, comprising a base and an electroconductive layer formed on at least one side of the base, the electroconductive layer being a mixed layer of at least one metal and at least one metal oxide.

Abstract: A utensil for use in preparing foods in a microwave oven comprises a microwave transparent, nonconductive, ceramic, opentop food receiving vessel, a microwave transparent, nonconductive, ceramic cover for closing the open top of the vessel, special glaze or coating sintered onto at least the interior surfaces of the vessel and cover or onto both the interior and exterior surfaces thereof; the glaze or coating being comprised of a dielectric matrix and semiconductive particles dispersed throughout the matrix; the percent loading of the conductive particles in the matrix being such that the food contained in the vessel is partially shielded from microwave energy and the glaze absorbs microwave energy and the glaze absorbs microwave energy and converts it to thermal energy concentrated at the utensil so that the outside surface of the food is browned and crisped and the food is cooked from the outside to the inside by the heat transferred to the food from the utensil, as well as being cooked in part from the ins

Abstract: A novel microwavable susceptor used for cooking expandable dough in a microwave oven is disclosed. Specifically, the susceptor comprises an inner region and an outer region, the inner region having a pattern of metalized and/or non-metalized portions wherein the intensity of the inner region is about from about 25% to about 75% and the outer region has an intensity arbitrarily set at about 100%. A cookie dough composition having desirable spreadable characteristics useful for baking in a microwave is also disclosed. The susceptor is reusable.

Abstract: A product for heating a load at different rates using microwave radiation provided at a substantially constant power level. The product may include a polymer matrix alone or in combination with a metal substrate, with the polymer matrix located on the surface of the metal substrate that does not contact the load and is thus disposed to the incident microwave radiation. The matrix includes dielectric and magnetic components in amounts that enable at least initial absorption of the incident radiation and thus initial thermalization of the radiation within the matrix. The matrix is designed to change its rate of thermalization and the rate at which it conducts thermalized radiation to the substrate and load after a predetermined time of exposure to the radiation at a predetermined temperature of the matrix.

Abstract: A container for use in a microwave oven formed from a microwave transparent material and having coated on at least part of at least one inner surface thereof a browning agent for transfer of a brown coloration to a surface of a food item.

Abstract: Materials and methods are disclosed for making microwave susceptor elements. The elements of this invention employ substrates, made of solid refractory materials, which are porous and liquid absorbent. The substrates, relatively microwave transparent per se, are rendered microwave interactive by a surface deposit of a finely subdivided microwave responsive substance. The substance is laid down from its dispersion in a volatile liquid medium which is later removed by evaporation. Susceptor elements thus made, be they large pieces or particulates, are uniquely suited for storing microwave generated heat up to elevated temperatures, subject only to the thermal stability of accessory materials. They also perform equally well in conventional ovens. The heat stored may be delivered to load objects during the heating step, in the oven, or afterwards, outside the oven.

Abstract: A collapsible, thin wall, plastic container includes a closed end, an annular peripheral side wall and an open end, the peripheral side wall including a plurality of annular steps or shoulders for enabling controlled axial collapse of the container to a compact, collapsed condition wherein a plurality of substantially concentric folds surround a remaining uncollapsed portion of the container; and a removable cap securable to the open end, the cap having a sealed chamber formed therein for holding a predetermined amount of foodstuff material.

Abstract: A package for heating food has a cover for covering a tray and provides an aluminum laminate for covering the tray side wall. The cover is configured to extend over the top opening or over the base of the tray and cover the tray side wall. In one embodiment, only side edge portions of the cover are formed of an aluminum laminate. In another embodiment, the entirety of the cover is formed of an aluminum laminate, in which case, the cover has lines of weakening positioned therein for tearing and removing a central portion of the cover.

Abstract: A packaging container for use in connection with microwave cooking of foodstuffs is provided. The container can be opened up so as to define an extended base area, allowing foodstuffs comprising individual items to be spread out during cooking. The extension is achieved by utilization of container portions not originally part of the base. The extended base area preferably is covered with microwave susceptible material.

Abstract: A collapsed flexible, e.g., paper, bag is provided which contains a charge of unpopped popcorn. Popping of the corn can be carried out in a microwave oven with the bag supported upon a pre-erected or collapsible stand, usually about 2 cm high, attached to the bag. The bag includes upper and lower opposing face panels connected together by longitudinally extending, centrally projecting gussets that are integral with the face panels. Prior to popping, the gussets are folded between the under and lower face panels of the bag and the bag is sealed at each end. A microwave heating susceptor is provided in the lower panel of the bag or elsewhere in the bag if desired. During popping of the popcorn kernels, the bag increases in size and the gussets expand outwardly as the bag becomes filled with popped kernels, hot vapor and steam.

Abstract: Low-fat pork skin pellets can be produced by steam cooking pork skin portions and if necessary oil cooking the steam cooked portions to produce pork skin pellets. The pork skin pellets are then placed in a microwavable container. When cooked in a microwave oven, the pork skin pellets puff to produce a pleasant tasting crispy pork skin snack food.

Abstract: A novel structure for use in the microwave cooking of foodstuffs for consumption is described. The structure includes an array of individual shapes of flexible electroconductive material normally opaque to microwave radiation supported on a microwave transparent substrate. Each of the individual discrete shapes of flexible electroconductive material has a thickness normally opaque to microwave radiation and is formed in an H-, I- or elongate strip shape. The individual discrete shapes are arranged on the substrate to define a space surrounding the periphery of each individual shape with the spaces defining a continuous aperture extending throughout the array and effective to generate thermal energy in the continuous aperture when the article is exposed to microwave energy and the foodstuff is in contact with or proximate to the aperture. The multiple layer article of manufacture is adapted to be formed into a packaging structure in which a foodstuff may be heated by microwave energy to an edible condition.

Abstract: A disposable package assembly for storage and subsequent microwave heating of a food item. The package assembly includes a container body having one or more raised lands integrally formed on the bottom surface thereof. The one or more raised lands support a microwave browning disk, and a food item is supported upon the browning disk. The one or more raised lands create an air space between the bottom of the container body and the browning disk to promote even circulation of heated air. A lid is disposed over the container body to enclose the food item.

Abstract: A packaging system is disclosed which includes a susceptor heating means having selective responsiveness to microwave radiation. The susceptor surface has a plurality of regions, where at least one region has an altered responsiveness to microwave radiation which is achieved by disruptions in the susceptor surface. A method for making regions of a susceptor selectively responsive to microwave heating by disrupting the continuity of the metallized film of the susceptor is also disclosed.

Abstract: Microwaveable packing compositions exhibiting improved temperature control are provided. These compositions comprise a dielectric substrate having at least a portion of at least one of its surfaces coated with a matrix composition containing susceptor particles as well as particles of a blocking agent selected from the group consisting of calcium salts, zinc salts, zinc oxide, lithopone, silica and titanium dioxide. Also disclosed is a microwaveable ink composition useful for the preparation of such packaging compositions as well as a process for manufacturing such packaging compositions.

Abstract: A gas-flushed microwavable easy-to-open food package is provided which is resistant to impact under temperatures at or below freezing and which is comprised of a flexible lidding film having oxygen-barrier properties hermetically and peelably sealed to a food compartment formed from a polypropylene copolymer material. The lidding film is preferably comprised of oriented polyester, and the food product compartment further comprises a peelable oxygen, barrier film, preferably formed of ethylene vinyl acetate, PVDC and a peelable polyethylene layer. The package is designed to contain a perishable food product, such as a wiener in a bun or other proteinaceous-farinaceous food combinations, and is preferably entirely or partially transparent so as to allow the consumer to readily observe the condition of the food product before purchase.

Abstract: A microwaveable food container is provided with an accessory which contains a heat assist to facilitate heating of the food. The accessory is secured to the container along two opposite edges of the accessory and is provided with perforations which allow the metallized heat assist to be easily removed. The remaining portion of the container may therefore be recycled.

Abstract: A microwave susceptor which includes a dielectric substrate and a dry layer of microwave active coating material overlaying at least a portion of the substrate is provided. The coating material includes a silicate binder and an active constituent and the weight ratio of the silicate to active is about 98:2 or less (i.e. less silicate). The dry layer is electrically continuous and has a surface concentration of active constituent of about 1 gram per square meter or greater. Sodium silicate is preferred as the binder and graphite is preferred as the active constituent. In addition additives such as saccharides, glycerine and plasticizers can be added to inhibit thermal shut down and to increase the flexibility of the dry layer. The susceptor can exhibit moderate heat performance or even high heating performance if desired.

Abstract: A thermocompensating susceptor is described comprising a microwave transparent sheet, e.g. paper, paperboard or plastic, having a layer thereon of a dried dispersion comprising a film forming vehicle together with two kinds of dispersed particles including microwave interactive particles such as a metal, metal oxide, carbon or graphite that absorbs microwave energy to produce heat in a microwave oven and electrically nonconductive thermocompensating particles of a mineral hydrate containing bound water of crystallization and having a dissociation temperature between about 100.degree. F. and 500.degree. F., at which temperature the bound water is released therefrom to prevent overheating of the laminate.

Abstract: An improved technique for uniformly distributing crisping or browning heat supplementation in disposable paper food carton or containers and the like used for microwave cooking, in which a metallized susceptor film is employed mounted to but intermediately spaced from the adjacent inner wall of the container to define and seal an air pocket which, in heating, improves the uniformity of the browning result through convection into air pocket and responsive flexing of the film.

Abstract: A microwave food heating package for food pieces such as french fried potatoes or fish sticks is described. The package includes one or more susceptor sheets folded in alternately opposite directions to provide accordion folds therein which define V-shaped pockets that serve as heating chambers for individual pieces of food. The susceptor sheet is formed from a microwave energy-absorbing material adapted to heat, brown or crispen the surfaces of the food sticks. The heating chambers preferably enclose the food sticks on all major surfaces and can be made by layering, i.e. stacking, segments of the accordion-pleated susceptor sheet material one above another to form individual heating chambers for the food pieces to crispen, toast or brown their surfaces during heating.

Abstract: A patterned microwave interactive element and laminate including a patterned microwave interactive element for use in forming food packaging materials that may be employed to store and subsequently cook the food stored therein are provided. The pattern of the microwave interactive element is selected to focus the heat generated to predetermined areas of the food contained in the packaging. Areas where the microwave interactive element has been deactivated may be formed by a variety of methods, such as by demetallization, by the application of an inactivating chemical, by mechanical means and the like, to create a preselected pattern of inactive areas relative to the active areas, thereby controlling the temperatures produced in different sections of the packaging material. Optimum browning and/or crisping of the microwave heated food product may be achieved by selecting a pattern of microwave interactive and inactive areas tailored to specific food products.

Abstract: A food package is provided wherein the accommodated food product, while remaining in the package, may be heated or cooked in a microwave oven. The food product has at least one predetermined portion thereof which requires enhanced heat while the product is being heated or cooked in the oven. The food package includes a container formed of heat resistant material which is pervious to the microwaves. A surface of the container is provided with an area which is in proximity to the predetermined portion of the food product requiring the enhanced heat. A metallized ink, consisting of metal particles suspended in an ink-like substance, is deposited on the surface area of the container. Thus, when the metallized ink is exposed to the generated microwaves, the required enhanced heat is produced in the vicinity of the surface area.