TWO-STAGE PROCESS FOR COOKING/BROWNING/CRUSTING FOOD BY MICROWAVE ENERGY AND INFRARED ENERGY

Abstract: A two-stage process for baking/crusting food products is proposed. The First Stage is carried out in a microwave oven chamber (10); the Second Stage is carried out beneath a gas or electric broiler (32). In both stages, the food is placed on a browning/crusting device (16) which provides a metal cooking surface (17), heated by adherent microwave lossy material (18) or on a smooth surface (45) of one or more blocks of microwave lossy ceramic (43) or microwave lossy igneous rock (40) which is supported in a metal tray (44a). In the first stage, a First Stage kit (30) includes a microwave transparent cover (24), a microwave transparent thermal insulating support (12) and the browning/crusting device (16). In the Second Stage, only the browning/crusting device (16) is used to complete the overall process. The browning/crusting device (16) is pre-heated in a microwave oven (11) to achieve an elevated browning/crusting temperature before applying food to the browning/crusting device (16).

Description: τw 9 STAGE PROCESS FOR COOKlNG/BRQHNING/CRUST ING FOOD BY MICROWAVE " ENERGY " AND ΪNF ' RARED ENERGY "~ Bfi _P .fθy NL) O!- IHL_INVENT ION Held of the invention - Ihis invention concerns a two-stage method for coo ing/browmng/crusting food: first, a microwave energy stage; and second, an infrared energy stage. The invention further includes preferred browning/crusting devices to support and contact food during each stage. Description of Prior Art - This invention improves over and increases the. utility of the microwave browning grill of U.S. Patent Nυ. 4,90ό.8ϋt.. and U.S.Patent No. 4,923,70^ u. :3. Patent Applications 3.N. 286,234, filed January 1Δ , 1989 and u.5. 5.N. 645,790, filed January 2 , 1991 improve over and increase the utility of the microwave shielded chamber of U.S. Patent No. 4 ,906,80t>. These copending applications disclose how the- cooking results, of food, cooked in a microwave oven, may be enhanced by a subsequent exposure to intrared energy in .. conventional thermal oven. These copending applications Dt'imarilv concern foods which, during cooking, produce liquid by-products . , e.g., sausages, whole chicken, and the like. in contrast, this invention primarily concerns foods which, during cookinc,, produce little or no liquid bv-products, e.g.. WO 92/14369 PCT/US91/01042 bread and cake. For any particular food, the results desired by the cook, dictate which apparatus and which cooking method to u e. U.S. Patents 3,701,872 and 3,777,099 describe preheating metal plates in a microwave oven by means of a microwave-absorptive heating member. U.S. Patents 3.731,037 and 3,881,027 disclose a microwave oven apparatus, with heating layers on the ceiling, floor and walls of the microwave chamber, and describe cooking food in a metal container in that microwave chamber. U.S. Patent 4,306,133 describes microwave cooking a fruit pie having double crust. U.S. Patent 3,914,967 describes microwave heating grill constructions. The prime advantage of microwave cooking over conventional cooking, is the ability of microwave energy to surround a food and to penetrate and release energy below the surface of a food. Microwave, energy, in a 700 watt microwave oven, sur¬ rounds and heats the mass of a food. In contrast, intrared en¬ ergy, from a 700 watt infrared broiler heating element will heat, only the exposed surface, in direct line-of-sight, of a food thereunder. When or^ desires to sear, crust, broil and brown large portions ol food, the full power, domestic microwave oven delivers typi¬ cally only 70C) watts. In comparison, a conventional gas or electric kitchen range broiler can deliver about 700Q watts. I follows that foods with large surfaces and heavy portions of food will brown and crust better under an infrared, conven¬ tion l broiler with its greater heating capability. It i an object, o÷ this invention to provide improved ways to combine ifiicrowave oven cooking with cooking under the broiier -. { __, conventional gas or electric ki chen range. It s another object of this invention to provide improved ways tv> broil , crust, fry, seai . and toast by combining sequential microwave energy and intrared energy cooking. It is another object of this invention to provide new methods foi combining sequential microwave energy and intrared energy cooking of foods such as baking pizza pies; cooking hot dogs and toasting hot dog rolls; baking two-crust meat pies and truit Dies, reheating Chinese noodles; baking cakes, cookies, rolls, fruit turnovers, biscuits, breads; and heating frozen convenience foods such as hors d'oeuvres, fried chicken and I-rench-tried potatoes. . L l§MENT OF THfc PRESENT INVENTION According to the present invention, a novel browning/crusting device has dual utility in cooking/browning/crusting when ex¬ posed to either microwave energy or intrared energy. There are ovens available which include both a microwave generator and an intrared broiler in their heating chambers tor alternate use. The methods of this invention may be practiced in such combined ovens.. According to this invention, certain foods are cooked/browned/crusted in two stages on a novel brown¬ ing/crusting device. The First Stage is carried out in a mi¬ crowave chamber on the preheated browning/crusting device. The Second Stage is carried out on the same browning/crusting de¬ vice beneath an infrared broiler. The browning/crusting is a microwave- lossy unit that can develop temperatures in the 350- 6bθ°F range when exposed to microwave energy in a microwave chambe . In the- First Stage, microwave cooking/browning/cruεting is car¬ ried out . A moisture confining, microwave transparent cover en. loses the browning/crusting device to define a cooking cham- be: . The 1 ood to be cooked/browned/crusted is placed in the cooking chamber on a preheated browning/crusting device. Any splatte; and moisture from the food, is confined within the cooking chamber during the First Stage. The First Stage ends when the food in contact with a cooking surface of the brown¬ ing/crust ng device has been browned/crusted as desired. At the end of the irst Stage of the method, the browning/crusting device, without the cover, is placed beneath an intrared broiler and the top surfaces of the food are browned/crusted. The brown ng/crusting device may b designed to be useful as a heated, insulateσ service platter and/or hot plate. lii a preferred embodiment, the browning/crusting device, com¬ prises a metal plate having an exposed metal cooking surface, which functions as a browning/crusting surface, and having an¬ other metal surface which is coated with a microwave lossy com¬ position which is in a heat transferring relationship with the metal plate. In a further preferred embodiment, the cooking surface is concave and the thickness of the microwave-lossy composition is greater at. the perimeter of the metal plate than at the center of the metal plate. In an alternative embodi¬ ment, the browning/crusting device is a block . or multiple blocks in an array) o1 microwave-lossy ceramic or microwave- lossy igneous rock. The block or blocks are. retained in a meta1 tray. lfi? browning/crusting device is supported on a microwave-trans¬ parent, heat-insulating member such as a non-lossy ceramic shallow bowl, tray or frame. Preferably, the cover is a heat- resistant, non-lossy glass bowl having a rim engaged with the perimeter of the heat-insulating container. DESCRIPTION OF THE DRAWINGS ' IGUR.: : is a cross-section view of a microwave oven chamber containing an insulator member, a brown ng/crusting device, and a cover tor practicing the First Stage of the invention. F IGUKt r IS a cross-section illustration of the brown¬ ing/crusting device, of FIGURE 1, on a broiler tray positioned beneath an intrared broiler for practicing the Second Stage of the invention. FIGURE 3 is a cross-section illustration of an alternative browning/crusting device on a heat-insulating tray, tor practicing the Second Stage of the invention. FIGURE 4 15. a. perspective illustration of a ceramic or igneous, rock cooking block within a metal tray which blocks microwave energy from entering the sides and base of the roc . FIGURE is a perspective illustration of plural ceramic or igneous rock blocks, assembled in an array within a metal tray, to function as an alternative embodiment of a browning/crusting device. FIGURE t is a cross-section of the browning/crusting device of FIGURE b taken along the plane 6-6. FIGURE / is a cross-section illustration, similar to FIGURE 1, showing a heat-insulating support member, a brown¬ ing/crusting device, a cover member, and a bread or cake pan tor practicing the First Stage of the inven¬ tion for baking/browmng/crusting bread or cake. FIGURE P. is a cross-section illustration of selected elements, of FIGURE 7 , including t-he browning/crusting device, positioned on a broiler tray, and the. bread or cake pan positioned beneath an intrared broiler for prac¬ ticing the Second Stage of the invention. FIGURE '-> is a cross-section illustration of a preferred brown¬ ing/crusting device, in an inverted position. DE3ORIPTION 0F___THE PRFFERRED EMB0DIMENT5 FIGURE l illustrates a microwave oven chamber 10 defined by a broken line 11. Positioned within the microwave chamber 10 is a heat-insulating member 12 having a generally horizontal base 1 _> upstanding sidewalls 14 and handles 15. The sidewalls 14 may be shortened and handles 15' (shown in phantom) may be pro¬ vided whereby the heat-insulating member 12 has a lower height. Side walls 14 are not required, but are convenient for support¬ ing other elements. Preferably, the heat-insulating member 12 i z . fabricated from microwave-transparent. heat-resistant, non- los.sv- glass-ceramics which will not. degrade under a gas flame i gas broiler heating unit. A browning/crusting device 16, in a preferred embodiment, in¬ cludes a metal plate 17 and a microwave-lossy composition 18 adhered tc- the under-surface of the metal plate 17. The metal olate 17 has a concave surface 19 and an upstanding perimeter bead 20 and a depending sidewall 21. It. will be observed that the- concave surface 19 presents a convex surface 22 on the op¬ posite side of the. metal plate 17. The. sidewall 21 has suffi¬ cient height, to position a microwave-lossy composition 18 above the base 13 of the insulating support 12. The metal plate 17 preferably is formed from aluminum having a thickness of ap¬ proximately 1/16 inch to 3/8 inch. Other heat-conductive met¬ als may be employed, such as stainless steel and carbon steel. Ihe microwave-lossy composition 18, preferably, is a high tem¬ perature curable binder (e.g., a poly epoxide) having dispersed therein particles of microwave-lossy materials, such as ter- rite, that become heated when exposed to microwave energy. FIGURE 9 illustrates an inverted browning/crusting device 16. Microwave-lossy composition 18 was poured into inverted grill Plate 17 as a liquid, uncured composition of terπte and a plastic binder. The convex surface 22 of the metal plate 17, and the l evel top surface 23 of the microwave-lossy composition i :~. . s.haρe the microwave lossy composition 18 relatively thin at the center and relatively thick at the. perimeter. In addition.. - perimeter groove formed by the under-surtace of the bead 20, . --■ filled with loss. composition 18. As a result, of the brown¬ ing/crusting device 16 having a larger concentration of mi¬ crowave-lossy composition at the perimeter, the larger concen¬ tration heats- the food contacting surface 19 more evenly than a uniform thickness of microwave lossy composition. in FIGURE l , a cover 24 has generally cylindrical sidewalls 25. a top 26 and a rim 27. One or more handles 28 are provided to facilitate lifting the cover 24 and to serve as, a support tor- cover 24 when it is disposed in i s rim-up condition as a bo l. The covei 24 preferably is formed from heat-resistant, non- lossy glass which is microwave transparent and light transpar¬ ent. The rim 27. of cover 24, mates with heat-insulating support 12 to produce an enclosed cooking chamber 29. The brown¬ ing/crusting device lo is confined within chamber 29. Moisture released, while heating food on browning/crusting device It., is. confined within the chamber 29. The confined moisture will condense on the relatively cool surfaces, of the cover 24 and w ll be retained within the chamber 29. OPE AT ION F I ST STAGE I he elements 30, illustrated in FIGURE 1, in microwave oven chamber 10. are exposed to microwave energy. The heat-insulat- i ng support 1? and cover 24 are microwave transparent and are not heated by microwave energy. The microwave-reflective metal plate 17 is not heated by microwave energy. The microwave- lossy composition 18 becomes heated by the microwave energy l hernia1 energy, from the heated microwave-lossy composition IE., is transferred to the metal plate 17 and the temperature of the metal plate 1 1 increases. Browning/crusting device 16 is pre¬ heated empty until it reaches a browning/crusting temperature. e.g. 350-650°F . Browni ng/crusti ng device lc. exposed to microwave energy, within the he t-conf lning chamber 29, is tree to rise to brown¬ ing te pei atures tar in excess of temperatures realized in prioi art metal heating grills for microwave oven use. For example, the browning utensil of U.S. Patent No. 4,496,815 has α metal , browning element whose maximum temperature is limited b the deformation temperature of its plastic support. After the browning/crusting device 16 is preheated, the mi¬ crowave chamber 10 is opened, the assembled First Stage ele¬ ments 30 (cover 24, heat-msulating support. 12 and brown¬ ing/crustl ng device 16.) are removed from the microwave chamber ID The cover is lifted, and an appropriate food, to be cooked/browned/crusted, is placed on the hot, metal cooking surface 19. (he cover 24 is returned. The re-assembled First Stage elements 30, with the food, are placed into the microwave chamber ID and exposed to additional microwave energy. The surfaces, of the food, which contacts the hot food-contacting surface 19. of the browning/crusting device It., are thermally browned/crusted as desired while the remainder of the food is cooked by microwave energy which passes through the microwave transparent, cover 24 and penetrates the food. OPE ATION SECOND ST GE After being exposed to microwave energy, the assembled First Stage elements 30 (the cover 24, heat-insulatmg support 12 and browning/crust ng device 16, ) , with the food thereon, are re¬ moved from microwave chamber lO. 1 he cover 24 is removed ex¬ posing the food on the food contacting surface 19. The Second Stage is commenced by removing the browning/crusting device, le, from the heat-insulating support 12, and placing it, with the food thereon, beneath an infrared broiler 32, on broiler tray or rack 4 '. as shown in FIGURE 2. The infrared broiler 32 may be an electrical resistance thermal energy generator, such as a resistance wire, nichrome bars or other well-known heating ele¬ ments. Alternativel , the intrared broiler 32 may be a com¬ bustible gas burner which is well-known in the broiling art. i n the F l '-st Stage of this process... prepared, frozen, tried, breaded chicken 33 and frozen- pre-cooked French-tried potatoes 3 were defro ted/heated and their bottom surfaces 35,37, con¬ tacting the food contacting surface 19, were browned/crusted as desired. In the Second Stage, both the food and the brown- ing/crusting device 16, are heated by infrared energy radiating from an infrared broiler 32. The upper surfaces 36,38, of the breaded chicken 33. French-tried potatoes 34 and the evoosed surfaces of the browning/crusting device 16 are heated. PRIOR ART In the prior art, multiple pieces of food had to be, individu ¬ ally turned over to brown both sides. In the prior art, glass- cera i.. browning platters with a layer of microwave-lossy tin oχ.ιde were available for browning foods in a microwave chamber. According to the present invention during the First Stage. > the undei -surface of the food is browned/crusted by direct con ¬ duction of heat in a microwave chamber; the Second Stage of browning/crusting is carried out on the upper surface of the food with infrared energy from an intrared broiler. Beneath the broiiet , the browned under-surtace is maintained hot by heat released from browning/crust ng device. Spot heating and selective heating and selective defrosting, of a food, that oc¬ curs, during the First Stage, equalizes, during the Second Stage, n which the food rests. " and completes cooking. ALTERNATIVE EMBODIMENT As shown in FIGURF 3, the browning/crusting device 40 may com¬ prise a microwave sate block 40 (square, rectangular, circular, oval . et cetera) of microwave-lossy ceramic or a microwave- lossy . igneous rock. Igneous rock blocks have been sold in the Uni ed States under the trade name LAVA ROCK. Rock and ceramic which includes a r or water pockets, are not recommended because t.hpv might explode when exposed to microwave energy. ' least one of the exposed flat surfaces 41, of block 40. has .- smooth surtacF and can function as a cooking surface for browm ng/crusti ng foods . The block 40, when exposed to mi- -,rowave energy, becomes uniformly heated. The block 40 prefer¬ ably is preheated to a browning/crusting temperature within the range of 450-650>F and food is cooked on the smooth surface 41 in First microwave Stage and a Second infrared Stage. The block 40 is preferably placed in a metal tray 44a as seen in FIGURE 5 Only the exposed surface 41 of the block 40 is seen in FIGURE 5. The. metal tray 44a preferably has sidewalls which terminate with the surface 41. The metal tray 44a blocks microwave energy from the sides and bottom, whereby microwave energy can penetrate the block solely through the exposed sur¬ face 41. further alternative embodiment of the invention is an array 42 of individual small blocks 43 of microwave lossy ceramic: or lgneous rock as shown in FIGURE 5, 6. The blocks 43 are assem¬ bled into a desired geometric shape (a rectangle is shown in FIGURE 5j A metal tray 44b is provided to retain the blocks 43 in the desired array and to prevent microwave energy from penetrating the blocks 43 except through the exposed surfaces 4b. One of the smooth surfaces 45 of each of the. blocks 43 is ma ntained in a common plane. 46 as shown in FIGURE 6. Those co-planer surfaces 45 function as a food contacting surface of the browning/crusting device 40 of FIGURE 3. The tray 44b acts a?, .-. microwave shield which also equalizes heat across the bot¬ tom of the rock and concentrates exposure to microwave energy on the top center of the food cooking surface. The tray 44b speer- . the heating to browning/crusting temperatures of sur¬ faces. 41 and 45 by preventing microwave energy from re. hing the- ottom of blocks. 40, 43. A 1 ■ ve pound block 40 may be heated for 30 minutes or more. It takes, longer to heat, heavy block 40 than to heat a metal device 1: : but : once heated, five pound block 40 remains hotter longer t.han device 16 when functioning as a hot, post-cooking serving plate. The heated blocks 43 can function as hot, post-cookinc hot cubes. ' to maintain heat of cooked foods. In FIGURE 3, the block 40 is shown directly on the insulated t.ra ^ 1 This embodiment, without a metal tray, may be em- ployed n the First Stage and/or in the Second Stage. A metal tray 44a as shown in FIGURE 5 is preferred, although not shown in FIGURE 3. I n FIGURE 7. a First Stage assembly 30 similar to that of FIG¬ URE 1 is illustrated in a microwave chamber 10. In FIGURE 8 a Second Stage assembly 31 similar to that of FIGURE 2 is illus ¬ trated. In FIGURE 8, the browning/crusting device 16 is posi ¬ tioned on a conventional kitchen range broiler tray or rack 47, beneath an intrared broiler 32. As shown in FIGURE 7, a cake/bread pan 50 has upward sidewalls 51 and a generally flat base 52. The base 52 is usually rect¬ angular although other geometric shapes such as circles, ovals and the like are known. In order to bake bread/cake, the. browni g/crusting device 16 is preheated in a microwave chamber 10 tc> a desired browning/crusting temperature, in the range 45(>-5S °F . The preheating can be carried out by placing the browning/crusting device 16 on the heat-insulating support mem¬ ber 12 during the preheating of the browning/crust ng device. 1 Thereafter a metal, bread/cake pan 50 containing bread dough 53 (or cake batter) having an initial upper surface shown by the broken 1 lne 54 , is placed on top of the food contacting surface 19 of the browning/crusting device 16. The cake/bread pan 50 will be in heat transfer relationship with the food contacting surface 19 and will receive thermal energy from the hot food contacting surface 19 by conduction and convection. The assem¬ ble 30. a?, shown i FIGURE 7 (including the cover 24) is re¬ turned to the microwave chamber lO w th the bread/cake pan 50. During the F rst Stage of the browning/crusting process (FIGURE .' ) . microwave energy passes through the microwave transparent covet 24 and directly into the bread/cake dough 53 causing the dough to become heated, to rise and to bake. The resulting cake/bread rises to a level indicated by the numeral 55. Mean¬ time the cake pan 50 has become heated by the high temperature of the browning/crusting device 16 with the result that the bottom of the bread/cake that is in contact with the heated c - '.e pan is browned/crusted. This ends the First Stage. The First Stage assembly 3θ of FIGURE 7 is removed from the i, - crowave chamber lθ. I n *-.he Second Stage. FIGURE 8, browning/crusting device 16 w th the bread/cake pan 50 containing microwave baked bre; I/cake at the l evel 55, is placed beneath an infrared broiler 32 whereby the topi surface 55 of the bread/cake is browned/crusted as de¬ sired by exposure to infrared energy. During the Second Stage browning/crusting of top surface 55, intrared energy from the broiler 32 also heats the exposed, metal surface 19 of the browning/crusting device 16. The intrared broiler 32 keeps de¬ vice lo at an elevated temperature, throughout the Second Stage. Ihe broiler element 32 may be heated during the First Stage of the process, so that, the broiler 32 is at its operating condi¬ tions, when the Second Stage commences. This sequence abbrevi¬ ates the overall duration of the browning/crusting process. ALTERNATE EMBODIMENT It is preferred not to heat the heat-insulating support member 12 beneath broiler 32. during the Second Stage. Instead the heat-inεulatmg member 12 may cool during the Second Stage. After the Second Stage, a relatively cool serving base heat-in- sulating member 12 may receive the high-temperature, brown¬ ing/crusting device 16. The cool, heat-insulating member 12 thus t,a ~ - added utility. It accepts the hot, browning/crusting device lc out from under the infrared broiler, and combines w th device lc to become a "sizzling skillet" food serving de¬ vice. An alternate embodiment is to place msulati^'- member 12 under- broiler 32 with device 16 during the Second Stage. While the present two-stage cooking method has been employed successfully cooking/ rowning/crusting tried chicken and French tried potatoes, the method may also be employed to brown/crust. pizza pies; to brown hot dogs and toast hot dog rolls; to bake two-crust meat pies and fruit pies; to reheat Chinese noodles; to bake cakes, cookies, rolls, fruit turnovers, biscuits, breads; to defrost and heat frozen convenience foods such as hors, d'oeuvres. tried chicken and French-fried potatoes.

Claims: Claim ; A method tor browning/crusting food, in two stages, comprising: In a first stage: placing a microwave-lossy browning/crusting device in a microwave chamber , said browning/crusting device including a metal food contacting surface on a metal tray supporting a non-metal food contacting surface; said browning/crusting device further being resistant, to heat, damage when exposed to infrared energy from an infrared broiler; exposing said browning/crusting device to microwaves until said food contacting surface is heated to a food browning/crusting temperature; placing said food to be browned/crusted on said food contacting surface to brown/crust said food in contact, with said food contacting surface; and In second stage: exposing sa d browning/crusting device and said food to infrared energy by placing said browmng/crusting device, with said food on said food contacting surface, beneath an intrared broiler whereby a surface of said food, opposed to said food contacting surface, is browned/crusted by said intrared energy from 2. The method of claim 1 wherein said browning/crusting device retains an elevated temperature, above room temperature, subsequent said second stage, and functions as a heated serving platter tor said food. .. The method of claim 1 wherein said intrared broiler is in said microwave chamber. 4. The method of claim 1 wherein said browning/crusting device includes a metal plate which has a metal food contacting surface and has a microwave-lossy composition in contact w th the opposite surface of said food contacting surface. b The method of claim 1 wherein said browning/crusting device comprises a microwave-lossy member, formed from microwave-lossy ceramic or from microwave-lossy igneous rock, said member having at least one smooth surface which is the said food contacting surface; said member being supported on a metal tray which shields the bottom and side walls of said member from microwave, energy. o. The method of claim 5 wherein said microwave-lossy member comprises multiple blocks of ceramic or natural rock, said blocks being assembled in an array with one flat surface of each block lying in a common plane which is said food contacting surface. I he method of claim 1 wherein said food is cooked by exposure to microwave energy, in said microwave chamber., on said browning/crusting device subsequent to said first stage browning/crusting and prior said second stage browning/crusting. '-; The method of Claim 1 wherein said intrared broiler is preheated while said food is browning/crusting on said food contacting surface within said microwave chamber during said first stage. 9. T e method of Claim 1 wherein said food is browned/crusted in a metal pan having a bottom surface that contacts the food contacting surface of the browning/crusting device. lϋ. Ihe method of Claim 9 wherein said food is bread and, during said first stage, bread dough is baked in said metal pan having a bottom surface in contact with said food contacting surface and, during said second stage, said baked bread is browned/crusted in said metal pan beneath said infrared broiler. 1 . Ih method of Claim 9 wherein said food is cake and, during said first stage, a cake batter is baked in said metal pan having a bottom surface in contact with saidood contacting surface and, during said second stage, said baked cake is browned/crusted in said metal pan beneath said intrared broiler.

Inventors: LEVINSON MELVIN L, LEVINSON, MELVIN, L.
Applicants: LEVINSON MELVIN L, LEVINSON, MELVIN, L.
Application year: 1991
Main classification: H05B6
IPC codes: A23L1, A47J36