US20060112952A1

US20060112952A1 - Heat shield for preventing bottom surface burning of baked foods

Info

Publication number: US20060112952A1
Application number: US11/331,768
Authority: US
Inventors: Dan Steinberg
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-11-08
Filing date: 2006-01-13
Publication date: 2006-06-01

Abstract

Baked goods are often burned by exposure to heat radiation (infrared rays) from heating coils in an electric baking oven. The infrared rays strike the bottom surface of bakeware and heat the surface to the point of burning. The present invention provides a heat shield that protects the bakeware from infrared rays and burning. The present invention comprises a metal sheet having corrugations or bumps. Bakeware is disposed on the bumps. The bumps make point contact with the bakeware, thereby limiting heat transfer to the bakeware. The bumps provide an insulating air gap between the heat shield and bakeware. Also included is a sheet disposed under a wire baking rack. The sheet blocks infrared rays. The sheet can be suspended by hooks or brackets, for example.

Description

RELATED APPLICATIONS

The present application is a continuation-in-part of copending patent application Ser. No. 10/983,767, filed on Nov. 8, 2004.
FIELD OF THE INVENTION
The present invention relates generally to oven bakeware and baking supplies. More particularly, the present invention relates to a simple device for preventing bottom surface burning of baked goods such as cookies, cakes, pies and bread.

BACKGROUND OF THE INVENTION

Cooking ovens, particularly electric models, have a tendency to burn or overcook the bottom portion of baked goods such as cookies, cakes, pies and breads. This typically results from infrared radiation striking the bottom of the cookie sheet or breadpan and heating it to an excessive temperature. Insulated (2-layer) cookie sheets are commonly used to avoid this problem. However, insulated breadpans or piepans are generally not available and insulated cookie sheets tend to be expensive. Also, insulated cookie sheets can still burn the bottom portion if the cookie sheet is a dark color (e.g. from baked-on food spills) that absorbs radiation.
It would be desirable to provide an inexpensive oven accessory that minimizes or eliminates burning of the bottom portion of baked goods. It would be particularly useful to provide an anti-burn baking accessory that can be used with a wide variety of bakeware (e.g. cookie sheets, breadpans and piepans).

SUMMARY

The present invention provides a heat shield for preventing bottom surface burning of baked foods in bakeware. The bakeware is supported by a heat shield. The heat shield comprises a sheet having an array of corrugations or bumps. The corrugations or bumps have limited thermal contact with the bakeware. The corrugations or bumps create an insulating air gap between the heat shield and bakeware.
Preferably, the corrugations or bumps have similar heights so that they make line or point contact with a planar surface disposed on and supported by the corrugations or bumps.
Preferably, the air gap is open in at least one lateral direction (i.e. in a direction parallel with the heat shield). An open air gap allows air flow into and out of the air gap. Preferably, the air gap is open laterally when bakeware having a flat bottom surface is disposed on the corrugations or bumps.
Also preferably, the heat shield is flat. A flat heat shield will provide an open air gap when bakeware with a planar bottom surface is disposed on the corrugations or bumps.
Also preferably, the heat shield and bakeware have a surface area of contact less than 30% or 10% of a total bottom surface area of the bakeware.
Also preferably, tips of the corrugations or bumps are coplanar.
The corrugations or bumps can have flat top portions, if the flat top portions have a surface area less than 20% of a total area of the heat shield.
Also, the corrugations or bumps can have heights so that tips of the corrugations or bumps conform of a nonplanar surface of the bakeware.
A method for preventing bottom surface burning is also provided. In the method, bakeware containing food is disposed on a heat shield having an array of corrugations or bumps, wherein the heat shield and bakeware have an air gap open in a lateral direction.
The present invention also includes a baking oven shelf rack having a heat shield suspended below the rack.

DESCRIPTION OF THE FIGURES

FIG. 1 shows an oven shelf with a suspended heat shield according to the present invention.
FIG. 2 shows an oven shelf with a heat shield suspended with L-shaped brackets.
FIG. 3 shows a wire baking rack with L-shaped brackets according to the present invention.
FIG. 4 shows the oven shelf with a heat shield having tabs.
FIG. 5 shows a perspective view of a heat shield with tabs.
FIG. 6 shows the oven shelf with a heat shield having corrugations or bumps. The heat shield is disposed on top of the wire baking rack.
FIG. 7 shows a heat shield with bumps.
FIG. 8 shows a heat shield with corrugations.
FIG. 9 shows a corrugated heat shield with flat tops that provide 2 dimensional contact with bakeware.
FIG. 10 shows a heat shield having an array of line segment corrugations.
FIG. 11 shows an embodiment in which the heat shield has bumps that are conformal to a bottom shape of bakeware.

DETAILED DESCRIPTION

The present invention provides a heat shield for preventing bottom surface burning of baked foods. The heat shield comprises a sheet having and array corrugations or bumps. In use, bakeware is disposed on top of and is supported by the corrugations or bumps. The corrugations or bumps define an insulating air gap between the heat shield and bakeware. The corrugations or bumps have limited surface area contact with the bakeware, and so tend to limit heat transfer to the bakeware. Preferably, the corrugations or bumps have only line contact or point contact with the bakeware. Preferably, tips of the corrugations or bumps are coplanar. Also preferably, the insulating air gap is open in a lateral direction, thereby allowing airflow between the heat shield and bakeware. Also, the heat shield of the present invention does not have an edge designed for mating with any particular bakeware. The present heat shield can be used with any kind of bakeware, particularly if the bakeware has a flat bottom.
Also included is an oven shelf having a heat shield suspended under the oven shelf. The heat shield protects bakeware on the oven shelf from overheating and bottom surface burning.
FIG. 1 shows a front view (i.e. view through an open oven door) of an oven 18 with an oven shelf according to the present invention. The oven shelf comprises a wire baking rack 20. The wire rack has a regular array of wires arranged in a grid, as is conventionally known. The oven 18 may have slots (not shown) for receiving and supporting the wire rack 20. The oven 18 includes electrical heating coils 22. The heating coils emit infrared radiation 24. The present invention includes a heat shield 26 suspended below the wire baking rack 20. In the particular example of FIG. 1, the heat shield 26 is suspended by hooks 28. The wire baking rack supports bakeware 29 such as a breadpan (shown), cookie sheet or pie pan (not shown).
The heat shield 26 can comprises sheet metal such as aluminum, stainless steel, or tin-plated steel. The heat shield can have a thickness of about 0.010-0.35 inches, for example.
The wire baking rack 20 can comprise a wire grid. Baking ovens commonly have wire grid baking racks, as well known in the art.
An insulating air gap 30 is defined between the heat shield 26 and the bakeware 29. The insulating air gap 30 can have a thickness 32 of about 0.1-1 or 2 inches. The thickness 32 of the air insulating layer is determined by the length of the hooks 28.
The heat shield 26 is opaque to infrared radiation. The heat shield can be reflective or absorptive to infrared radiation.
In operation, the heat shield 26 prevents infrared radiation from directly striking and heating the bottom surface of the bakeware 29. The heat shield 26 absorbs or reflects infrared radiation 24. Hence, the bakeware and baking goods are heated by contact with hot air, and indirect infrared radiation (i.e. infrared emitted from oven sidewalls or heat shield). In this way, the present heat shield 26 prevents bottom surface burning of the food within the bakeware 29. The heat shield 26 tends to cause the oven to have baking characteristics similar to a convection oven, since heat is transferred to the food mainly by contact with hot air.
Also, the heat shield can have holes (not shown) so that a controlled amount of bottom surface browning is provided.
It is noted that the present heat shield will tend to increase the required baking time, typically by about 10-20%. Holes in the heat shield will reduce the baking time required, while still providing substantial protection against bottom surface burning.
FIG. 2 shows an embodiment of the invention in which the heat shield 26 is suspended by L-shaped brackets 34. The brackets 34 are attached to the wire baking rack 20. The L-brackets 34 can be made of steel and permanently welded to the wire rack 20. The brackets 34 may allow the heat shield 26 to slide into and out of the oven 18. The L-shaped brackets thereby facilitate cleaning of the shield 26.
FIG. 3 shows the wire rack 20, L-brackets 34 and heat shield of FIG. 2. The heat shield can be removed and inserted by sliding in the direction of the arrows 36. The heat shield can be shaped like a tray, with upturned edges (not shown).
FIG. 4 and FIG. 5 illustrate another embodiment in which the heat shield 26 has tabs 38 for suspending the heat shield 26. The tabs 38 are wrapped partially around the wire baking rack 20. In this embodiment, the heat shield can be made of thin, bendable sheet metal so that it can be bent around the wire rack 20 by hand. The heat shield 26 in this embodiment can be disposable and made from thin stamped aluminum.
FIG. 6. illustrates a preferred embodiment in which the heat shield 26 comprises an array of corrugations 40 or bumps 42. The height of the corrugations or bumps determines the thickness of the insulating air gap 30. The thickness 32 of the air gap 30 can be about 0.01 to 1 inches, or, preferably, in the range of about 0.025-0.25 inches. A bump height of about 0.075 to 0.125 inches is adequate for most baking applications, and is simple to manufacture. The corrugations 40 or bumps 42 can be formed by rolling or stamping of sheet metal, for example. The corrugations or bumps preferably are designed so that only line contact or point contact occurs between the bakeware 29 and the corrugations or bumps. With the area of contact limited to line contact or point contact, the heat transfer between the heat shield and bakeware will be greatly reduced. Preferably, the area of contact between the heat shield and bakeware will be less than 20%, 10% or 5% of the total area of the bakeware.
Preferably in the invention, the air gap 30 is open in a lateral direction 49. The open nature of the air gap 30 allows air to flow between the bakeware and the heat shield, which provides additional protection against overheating of the bakeware and bottom surface burning. Also, the open nature of the air gap allows warm air to flow into the air gap, which tends to reduce the baking time.
It is noted that the heat shield may have upturned edges 51 circumscribing the periphery. However, the heat shield will be considered to have an open air gap provided that the edges 51 are spaced away from the bakeware 29 such that air can flow laterally into the air gap 30 from at least one side. Also, if the heat shield has upturned edges 51, the edges 51 will not be designed to mate or contact an edge of the bakeware, and the edges will not be designed to fit or conform to any particular kind of bakeware. For this reason, it is preferable for the bakeware to be flat and to have bumps or corrugations that are coplanar. Also, if an upturned edge is provided, the edge 51 preferably is shorter than the corrugations or bumps.
The heat shield is preferably flat so that it can be used with any bakeware that has a flat bottom surface. A flat heat shield 26 will produce an open air gap 30 (on all sides of the bakeware) when mated with bakeware having a flat bottom surface (provided that the bakeware is smaller than the heat shield in the case where upturned edges 51 are present). The term “flat” in this context means that the heat shield is flat in regions away from the corrugations 40 or bumps 42, and that the heat shield is generally planar on a scale larger than a size of the corrugations or bumps.
FIG. 7 shows a perspective view of a flat heat shield with the array of bumps 42 according to the present invention. The bumps 42 are arranged in a rectangular grid pattern, though other patterns (e.g. a hexagonal array or random array) are possible. Preferably, all the bumps 42 are similarly formed (e.g. with similar shapes), and have similar heights so that tips of the bumps are coplanar. The bumps 42 should be located close enough to one another so that bakeware 29 will be stably supported (e.g. in contact with at least 3 bumps). Typically, the bumps should be separated by about 1-2 inches. Typically the heat shield will have about 25-400 bumps.
It is noted that the bumps 42 are not necessarily formed by stamping. The bumps can comprise small needles or wire points 44 that support the bakeware by the tips. Also, the bumps can comprise small sections (e.g. triangles, half-circles) of heat shield material cut and bent upwardly 46. Also, the bumps can comprise small curved pieces of metal spot-welded to the sheet. Such features will have a very small contact area with the bakeware 29. Preferably, the bumps are smooth and do not have holes or sharp edges. Smooth bumps are easier to clean.
FIG. 8 shows a perspective view of a flat heat shield having an array of corrugations 40. It is important to note that the corrugations do not need to be straight lines as shown in FIG. 8. Curved or wavy corrugations are within the scope of the present invention and appended claims. Also, the corrugations do not need to extend the entire width of the heat shield. FIG. 9, for example shows a top view of a heat shield with an array of line segment corrugations 40. The corrugations 40 should be located close enough to one another so that bakeware 29 will be stably supported (e.g. in contact with at least 2 or 3 corrugations). Typically, the corrugations should be separated by less than 1-2 inches.
It is noted that the corrugations can have flat bottoms and flat tops, so that the heat shield and bakeware have more than line or point contact (i.e. 2-dimensional contact). For example, the heat shield and bakeware can have 25% of the surface area in contact. Such contact can provide for controlled bottom surface browning of baked goods. FIG. 10, for example, shows a side view of a corrugated heat shield with raised flat areas 50 that will provide about 25% contact with bakeware.
The present heat shield can have a wide range of sizes, but will typically be designed to be slightly smaller than a conventional oven rack. For example, a conventional oven rack typically has dimensions of about 17×20 inches. The present heat shield can be about 15×18 inches. With the heat shield slightly smaller than the oven rack, air can circulate around the perimeter of the heat shield so that air may circulate throughout the oven. Also, it is noted that the heat shield can have a size and shape to match particular styles and pieces of bakeware. For example, the heat shield can be round for use with round cake pans or pie pans.
It is also noted that the heat shield can have holes so that a portion of infrared radiation (e.g. less than 50%, 35% or 25%) passes through the heat shield 26. A heat shield 26 with holes may provide a controlled amount of bottom surface browning. Also, holes will tend to shorten the amount of time required for baking, compared to a heat shield without holes. Bottom surface browning may be desired in certain baking applications (e.g. if a crisp crust is desired). Holes can be located on the bumps or corrugations, or in areas of the heat shield between the bumps or corrugations.
Preferably, all the bumps have the same height so that all the bumps simultaneously make contact with a planar surface (i.e. so that the tips of the bumps are coplanar). However, the bumps can also be designed to have different heights so that the tips conform to the bottom contour of curved bakeware. FIG. 10, for example, shows a cross sectional view of a well known bundt cake pan 52, which has an approximately toroidal shape. In regions 54, the bumps 42 of the heat shield are shortened to accommodate the curved bottom surface of the cake pan 52. The bumps 42 have heights that conform to the bottom surface shape of the pan. With the bumps 42 having heights conformal to the cake pan 52, the cake pan 52 will “lock” with the heat shield 26 so that the cake pan cannot slide or move on the heat shield 26. Also, the heat shield in FIG. 10 has a central hole 57 to allow increased air flow between areas above and below the heat shield.
The present invention provides a heat shield that prevents bottom surface burning of baked goods. The present heat shield can be used with a wide variety of bakeware such as cookie sheets, pie pans, breadpans, muffin pans and the like. The present bumpy baking sheet will prevent bottom surface burning in any bakeware resting on the corrugations or bumps.
It will be clear to one skilled in the art that the above embodiment may be altered in many ways without departing from the scope of the invention. Accordingly, the scope of the invention should be determined by the following claims and their legal equivalents.

Claims

1. A heat shield for preventing bottom surface burning of baked foods baked in bakeware supported by the heat shield, comprising:

a sheet having an array of exposed corrugations or bumps, wherein the corrugations or bumps create an insulating air gap under the bakeware supported by the corrugations or bumps.

2. The heat shield of claim 1 wherein the corrugations or bumps have similar heights such that the corrugations or bumps make line contact or point contact with a planar surface disposed on the corrugations or bumps.

3. The heat shield of claim 1 wherein the air gap is open in at least one lateral direction thereby allowing air flow into and out of the air gap.

4. The heat shield of claim 1 wherein the heat shield is flat, whereby the air gap is open in a lateral direction when bakeware having a flat bottom surface is disposed on the corrugations or bumps.

5. The heat shield of claim 1 wherein the heat shield has upturned edges, wherein the upturned edges are shorter than the corrugations or bumps, and wherein the upturned edges are not designed to fit or mate with any particular shape of bakeware.

6. The heat shield of claim 1 wherein the heat shield and bakeware have a surface area of contact less than 10% of a total bottom surface area of the bakeware.

7. The heat shield of claim 1 wherein tips of the corrugations or bumps are coplanar.

8. The heat shield of claim 1 wherein the corrugations or bumps comprise flat top portions that provide 2 dimensional contact with bakeware, and wherein the flat top portions comprise less than 20% of an area of the heat shield having corrugations or bumps.

9. The heat shield of claim 1 wherein the bakeware has a nonplanar bottom surface, and the corrugations or bumps have tips with heights that conform to the nonplanar bottom surface.

10. A method for preventing bottom surface burning of foods baked in bakeware, comprising the steps of:

a) disposing the bakeware containing food on a heat shield having an array of exposed corrugations or bumps, wherein the corrugations or bumps support the bakeware and create an insulating air gap under the bakeware;

b) baking the food by applying heat below the heat shield.

11. The method of claim 10 wherein the corrugations of bumps make line or point contact with the bakeware.

12. The method of claim 10 wherein tips of the corrugations or bumps are coplanar.

13. The method of claim 10 wherein the air gap is open in at least one lateral direction.

14. The method of claim 10 wherein step (b) is performed by heating with an electrically powered resistance heater.

15. A baking oven shelf for supporting bakeware, comprising:

a) a wire baking rack comprising a plurality of wires arranged in a grid;

b) a metallic heat shield below the wire baking rack, and suspended from the wire baking rack.

16. The oven shelf of claim 15 wherein the heat shield is suspended less than 2 inches below the wire baking rack.

17. The oven shelf of claim 15 wherein the heat shield is suspended by hooks.

18. The oven shelf of claim 15 wherein the heat shield is suspended by L-brackets.

19. The oven shelf of claim 15 wherein less than 25% of the heat shield comprises holes.