Electric heating – Microwave heating – Cookware
Reexamination Certificate
2001-12-20
2003-05-06
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
Cookware
C219S734000, C426S118000, C426S234000, C099SDIG014, C229S903000
Reexamination Certificate
active
06559431
ABSTRACT:
BACKGROUND
The present invention relates to the field of cooking devices. More particularly, the present invention relates to a steam tray for use in a microwave oven for cooking meats, vegetables, and other food products.
Consumers often prefer to cook food in a microwave oven rather than conventional ovens because of the reduced cooking time required to heat foods in a microwave oven. Unfortunately, cooking desirable and tasty food in a microwave oven can be a difficult task. Foods cooked in a microwave oven tend to be tough and/or dry in texture and consistency rather than tender and moist. When liquid is added to the food in an attempt to retain moisture, the food can become soggy and undesirable. In addition, microwave ovens do not evenly distribute heat to the product being cooked. This results in a cooked food product that may be very hot in one area, but cold in another area. Because of these problems, many people consider microwave cooking to be problematic and generally undesirable.
One method for improving the texture and consistency of food cooked in a microwave oven is to use steam generated by the heated food product to assist in cooking the food. Cooking with steam not only provides moisture for the food being cooked, but also results in more consistent heating throughout the food product. In order to retain steam in a cooking container when cooking food in a microwave oven, the container must be at least partially sealed. A lid covering the cooking container is often used to provide such a complete or partial seal.
When a container is sealed and used in a microwave oven, heat, steam and pressure build rapidly within the container. Of course, this rapid build up of heat, steam and pressure only continues to build until the container holding the food must somehow be relieved of the pressure. This relief often comes in the form of an explosion of the lid from the container. When the lid explodes from the container, food is typically spewed from the container, resulting in a mess on the inside of the microwave oven. In addition to the mess, the explosion also thwarts the efforts to use steam to cook the food within the container because the container is no longer sealed. Because the container is not sealed, all pressure within the container is lost, and heat and steam flow freely out of the container. Thus, for effective steam cooking of food within a microwave oven, a sealed container having a pressure relief system is desirable.
While a sealed container having a pressure relief system is desirable for cooking food in a microwave oven, many consumers do not want to hassle with transferring food into a special container for microwave cooking. This is especially true of pre-packaged food products, such as frozen food dinners, purchased by consumers for the express purpose of rapid heating in a microwave oven to produce a quick meal for the consumer. Consumers purchasing pre-packaged food products want a safe, convenient and tasty meal that can be prepared in a very short amount of time. Consumers also want to be provided the opportunity to cook pre-packaged food products in the packaged they were purchased in without the hassle of transferring the food from one container to the next.
Another problem with pre-packaged meals such as frozen dinners is that the packages that the dinners come in must be prepared before the food can be cooked. For example, when cooking frozen dinners, trays must typically be removed from a box that holds the tray. In addition, holes must be poked in the film that covers the tray. As mentioned above, if a hole is not poked in the film, the film may explode from the tray during cooking, resulting in a mess. Therefore, it would be desirable to provide a pre-packaged frozen dinner that may be transferred directly from the freezer to the microwave without the hassle of removing the frozen dinner from a box or poking holes in film that covers the tray containing the food.
Accordingly, it would be desirable to produce a sealed container having a pressure relief system allowing excess pressure to be removed from the container when cooking food in a microwave oven. It would also be desirable if such container were cheap and inexpensive to produce such that it could be used with pre-packaged food products, such as frozen dinners. It would be further advantageous if the container could be transferred directly from the freezer to the microwave without the need for additional preparation before cooking.
SUMMARY
A microwave cooking tray and sleeve assembly comprises a plastic tray for retaining pre-packaged foods, such as a frozen dinner. The tray includes at least one sidewall that defines a tray interior where the food is retained. The at least one sidewall is bounded by a rim that provides a surface along the top of the sidewall. A plastic film material provides a heat seal that is attached to the rim and covers the tray interior. The film is hermetically sealed to the tray and thus provides an air tight package for the food in the tray before it is cooked. At least one vent is positioned upon the rim of the tray. The vent creates a weakened portion on the heat seal.
The apparatus also includes a cardboard sleeve for holding the tray. The sleeve is designed to protect the tray during shipping and other handling before cooking, and is also designed for use when cooking the tray. The sleeve includes a sleeve top, at least one sleeve side and at least one port. When the tray is held by the sleeve, the sleeve top is positioned against the heat seal and the rim is positioned against the at least one sleeve side. Also, the at least one port is aligned with the at least one vent when the tray is retained within the sleeve.
When the consumer desires to cook the food in the tray for consumption, the consumer takes the tray and sleeve assembly and places the entire assembly in a microwave oven. When the microwave oven generates radiant energy, it travels through the sleeve and tray and heats the food positioned in the tray. As the food cooks, it gives off water vapor and steam is generated. The steam and heat from cooking the food causes pressure to build in the hermetically sealed tray. As the pressure continues to build, the vents direct pressure at the weakened portion of the heat seal. Because the size of the rim is reduced at the vents, the hermetic seal between the rim and the heat seal is weakest at this point. Thus, pressure inside the tray causes the seal to first break completely away from the rim near the vents. When the seal breaks, an opening in the seal is created and steam and heat escape from the tray at the vents. Because the ports in the sleeve are directly aligned with the weakened portion of the seal and the vents, the steam generated during cooking is allowed to escape the sleeve through the ports.
Accordingly, the present invention provides a sealed container having a pressure relief system allowing excess pressure to be removed from the container when cooking food in a microwave oven. The container is also cheap and inexpensive to produce such that it may be used with pre-packaged food products, such as frozen dinners. The assembly also be transferred directly from the freezer to the microwave without the need for additional preparation before cooking.
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Leung Philip H.
Nagle, Jr. David W.
Steamway Franchise Sales, Inc.
Stites & Harbison PLLC
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