Uniform microwave heating of food in a container

Abstract

The invention relates to a device and method for ensuring more uniform heating of food by microwaves. The method includes providing food in a portion having a predetermined size and shape; and providing a container adapted for receiving and reheating the portion of food in a microwave oven. The container forms a supporting cavity having peripheral sides and a bottom side, with the portion of food placed within the supporting cavity. The peripheral sides of the container are circumferentially shielded by a microwave reflective material that forms a circumference having axial and transverse distances that are determined so as to change the wavelength of resonant modes inside the food thereby resulting in a more uniform heating food pattern.

1 . A method for ensuring a more uniform heating of food by microwaves comprising: 
 providing food in a portion having a predetermined size and shape;    providing a container adapted for receiving and reheating the portion of food in a microwave oven; wherein the container includes a supporting cavity having peripheral sides and a bottom side, with the peripheral sides of the container being circumferentially shielded by a microwave reflective material such that the microwave reflective material on the peripheral sides forms a circumference having axial and transverse distances that are determined so as to change the wavelength of resonant modes of microwave energy in the supporting cavity;    placing the portion of food in the supporting cavity; and    heating the food and container with microwaves so as to expose the food to the changed wavelengths of resonant modes of microwave energy in the cavity thereby resulting in a more uniform heating food pattern and a more uniform heating of the food.    
   
   
       2 . The method of  claim 1 , wherein the microwave reflective material forms a resonating layer having a transverse distance at the surface of the food of about 12 cm or less.  
   
   
       3 . The method of  claim 1 , wherein the resonating layer has a closed rounded contour.  
   
   
       4 . The method of  claim 1 , wherein the microwave reflective material forms a resonating layer having an oval contour with an axial distance of about 20 cm or less.  
   
   
       5 . The method of  claim 1 , wherein the microwave reflective material forms a resonating layer having a height of about 10 to 60 mm.  
   
   
       6 . The method of  claim 1 , wherein the microwave reflective material forms a resonating layer having a transverse distance at the surface of the food within a range of from 15 to 20 cm and an axial distance at the surface of the food within a range of from 20 to 26 cm.  
   
   
       7 . The method of  claim 1 , wherein the microwave reflective material forms a resonating layer having a height of 25 to 45 mm.  
   
   
       8 . The method of  claim 1 , wherein the cavity predominantly supports TE n,m,l  modes where n, m, l are such that 0≦n≦4, 0≦m≦2 and 0≦l≦1.  
   
   
       9 . The method of  claim 1 , wherein the bottom side of the container is substantially free of shielding material.  
   
   
       10 . The method of  claim 1 , wherein the reflective material forms at least a part of a supporting stand that substantially nests the container in a removable manner.  
   
   
       11 . The method of  claim 10 , wherein the stand has a body portion with a wedge-shaped receiving microwave reflective surface to snuggly engage the complementary surface of the container and leverage means pivotally associated to the body portion to act on the bottom surface of the container to disengage the container from the wedge-shaped receiving surface.  
   
   
       12 . The method of  claim 1 , wherein the microwave reflective material has a thickness of at least 3.2 microns and is coated upon or attached to the sidewalls of the container.  
   
   
       13 . The method of  claim 1 , wherein the container is made of ceramic, glass, plastic, cardboard or combinations thereof.  
   
   
       14 . The method of  claim 1 , wherein the reflective material is in the form of a shielding aid member that is configured to be placed substantially around the peripheral sides of the container and is disposable after a finite number of uses.  
   
   
       15 . The method of  claim 14 , wherein the shielding aid member is a single use piece adapted to surround the peripheral sides of a non-disposable container.  
   
   
       16 . The method of  claim 15 , wherein the shielding aid member comprises a layer of cardboard or plastic which is associated with a microwave reflective layer.  
   
   
       17 . The method of  claim 1 , which further comprises removing the food portion in a frozen state from a package of a defined shape and size prior to placing the food portion in the container, wherein the shape and size of the packaged food portion are predetermined to substantially match the shape and size of the cavity of the container.  
   
   
       18 . The method of  claim 17 , wherein the package is disposable and removed for microwave heating of the food and wherein the food is placed in the cavity of the container in a manner to snuggly fit into the cavity of the container.  
   
   
       19 . The method of  claim 17 , wherein the portion of food is filled in a thermoformed package cell that precisely determines the size and shape of the food portion.  
   
   
       20 . A container assembly adapted for receiving and reheating of a food portion with microwaves; comprising a container forming a cavity having peripheral sides and a bottom side for the portioned food to be placed within the cavity, with the peripheral sides of the container being shielded by a microwave reflective material and the microwave reflective material of the peripheral sides defining a circumference having axial and transverse distances that are determined so as to promote propagation of certain resonant modes of microwave energy inside the cavity and in a food portion that is placed into the cavity, thus resulting in a more uniform heating pattern for a more uniform heating of the food portion.  
   
   
       21 . The container assembly of  claim 20 , wherein the microwave material forms a resonating layer having a transverse distance of about 13 cm or less, an axial distance of about 20 cm or less, and a height of about 10 to 60 mm.  
   
   
       22 . The container assembly of  claim 20 , wherein the microwave material forms a resonating layer having a transverse distance of from 18 to 22 cm and an axial distance of from 20 to 26 cm.  
   
   
       23 . The container assembly of  claim 20 , wherein the bottom side is substantially free of reflective material.  
   
   
       24 . The container assembly of  claim 20 , wherein the resonating layer has a circular or oval contour.  
   
   
       25 . The container assembly of  claim 20 , wherein the resonating layer is arranged to predominantly support in the cavity TE n,m,l  modes where n, m, l are such that 0≦n≦4, 0≦m≦2 and 0≦l≦1.  
   
   
       26 . A stand-like device for improving the heating of food in a container which comprises a support body of a shape adapted for receiving a container in a removable manner and a circumferential shielding surface of microwave reflective material adapted to be positioned substantially adjacent to peripheral sidewalls of the container.  
   
   
       27 . The stand-like device of  claim 26 , wherein the microwave reflective material of the circumferential shielding surface is defined by axial and transverse distances that are determined so as to change the wavelength of resonant modes inside the cavity and inside of a food portion placed within the cavity thereby resulting in a more uniform heating food pattern and a more uniform heating of the food portion.  
   
   
       28 . The stand-like device of  claim 26 , wherein the support body is made of a metal and includes a wedge-shaped receiving surface to snuggly engage the complementary surface of the container, and leverage means pivotally associated to the metal body to act on the bottom surface of the container to disengage the container from the wedge-shaped receiving surface.  
   
   
       29 . A combination comprising a food container and a stand-like device for improving the heating of food in the container, wherein the stand-like device comprises a support body of a shape adapted for receiving the container in a removable manner and a circumferential shielding surface of microwave reflective material adapted to be positioned substantially adjacent to peripheral sidewalls of the container.  
   
   
       30 . The combination of  claim 29  further comprising a food in the container.  
   
   
       31 . A method for more evenly heating a meal served in a reusable dish by microwaves which comprises placing a food portion in the stand-like device of  claim 26  and subjecting the device and food portion to microwaves to obtain a more uniform heating of the food portion.  
   
   
       32 . The method of  claim 31 , wherein the dish is a “plat à sabot”, a “china plate” or another ceramic dish or a plastic dish.  
   
   
       33 . A shielding aid for improving the microwave heating of food in a container which comprises a band of microwave reflective material of a shape configured for surrounding the peripheral sides of the container to provide a circumferential shielding surface of microwave reflective material, wherein the band is made of a destroyable material adapted for a finite number of uses, and wherein the band forms a microwave reflective circumference having axial and transverse distances that are determined so as to change the wavelength of resonant modes of microwave energy in the supporting cavity to provide more uniform heating of the food in the container.  
   
   
       34 . The shielding aid according to  claim 33 , wherein the band is a thin band of cardboard or plastic coated with a reflective material configured to connect or attach to the sides of the container.  
   
   
       35 . The shielding aid according to claims  33 , wherein the band has substantially the form of a crown.  
   
   
       36 . The shielding aid according to  claim 33 , wherein the band is destroyed by the effect of separating the band from the container after heating.  
   
   
       37 . The shielding aid according to  claim 36 , wherein the band comprises an adhesive layer at its inner surface to adhesively attach to the sides of the container and wherein the effect of separating the band from the container after heating destroys the adhesive layer.  
   
   
       38 . The shielding aid according to  claim 36 , wherein the heating creates a tearing of the band.  
   
   
       39 . The shielding aid according to  claim 36 , wherein the band comprises a shrinkable polymeric material that shrinks when exposed to microwave heating.  
   
   
       40 . A method for more evenly heating a meal served in a dish by microwave heating which comprises placing the food in the dish, placing the shielding aid of  claim 33  about the sides of the dish to shield it, and subjecting the shielded dish to microwave heating to obtain a more uniform heating of the food in the dish.