WO2001023276A1

WO2001023276A1 - Method of packaging and cooking food in an ovenable container

Info

Publication number: WO2001023276A1
Application number: PCT/US2000/026635
Authority: WO
Inventors: Michael S. Urso; Harry A. Rubbright
Original assignee: The Dow Chemical Company
Priority date: 1999-09-30
Filing date: 2000-09-28
Publication date: 2001-04-05
Also published as: WO2001023471A1; AU7620800A; CO5160368A1; AR025935A1; AU7620700A

Abstract

A method for packaging and cooking food in the same container is provided in which food is placed in an ovenable container, and a lid is placed on the container to store the food until it is ready to be cooked. The container with the food may be heated up to a temperature of 600 °F for a period of time sufficient to cook the food. The ovenable container comprises a filler, a fibrous material, and a binder selected from natural or synthetic latexes and natural and synthetic dispersed polymers.

Description

METHOD OF PACKAGING AND COOKING FOOD IN AN OVENABLE CONTAINER

The present invention relates to a method of packaging and cooking food in an ovenable container which may be heated to high temperatures in an oven, and more particularly, to a method which allows fresh or frozen food to be prepared, heated, and served in the same ovenable container.

In recent years, the desire for disposable containers which can be used to package and cook food has increased. For example, disposable containers may be used to package frozen foods which may then be heated and served within the container. Such containers have been typically comprised of paper, paperboard, plastics such as polystyrene and polyethylene terephthalate, metals such as aluminum, or combinations of these materials. While aluminum foil can be used at high temperatures in conventional ovens (i.e., electrical or gas heating ovens), efforts have been made to provide containers formed from materials which are suitable for cooking in both conventional and microwave ovens. The art has called such containers "dual ovenable" containers.

Dual ovenable containers currently in use are typically comprised of plastic or paperboard; however, such materials are limited for use in conventional ovens at temperatures of less than about 350°F. At higher temperatures, such containers tend to degrade, darken, deform, and emit odors, resulting in an unfavorable appearance and smell, both for the container and the food contained therein.

A number of coatings/films have been developed for paperboard substrates to increase their heat resistance for use as ovenable containers. For example, Seung et al., U.S. Patent No. 5,494,716 teach an aqueous coating including a styrene-acrylic latex which provides heat resistance. Marx et al., U.S. Patent No. 5,203,491, teach a press-formed container comprising an inner layer of parchment paper laminated to an outer base of ovenable paperboard. Calvert, U.S. Patent 5,418,008, teaches a barrier coating for paperboard packing comprising a water-based emulsion coating of an acrylic copolymer resin and a high density polyethylene wax. However, such coatings have been found to provide heat resistance only up to about 400°F to 450°F. For some applications, it is desirable to heat food for short periods of time at higher oven temperatures of up to 600°F. For example, in the pizza industry, it is desirable to reduce cooking time in order to reduce customer waiting time and increase the through-put of existing equipment by cooking the product at temperatures exceeding 450°F up to 600°F.

Accordingly, there is still a need in the art for a method of preparing, heating and serving food in the same container, which container may be used in an oven at high temperatures without generating objectionable odors from the container, and without introducing an objectionable flavor to the food.

The present invention meets that need by providing a method for preparing, cooking, storing and packaging food in the same container, where the container may be used to cook foods in an oven at high temperatures (i.e., greater than 400°F up to 600°F) without generating an objectionable odor from the container or introducing an objectionable flavor to the food. Because the container may be heated to higher temperatures, the time required to cook foods is reduced. The container also allows food to be prepared, packaged, stored, cooked, and served all in the same container. By "cook", it is meant that food may be cooked, heated or reheated in the container. According to one aspect of the present invention, a method for packaging and cooking food in the same container is provided which comprises providing an ovenable container and a lid adapted to be fitted on the container; placing food in the container; placing the lid on the container; storing the food in the container; and heating the container with or without the lid for a period sufficient to cook the food; where the container comprises a filled composite material containing a filler, a fibrous material, and a binder selected from natural or synthetic latexes and natural or synthetic dispersed polymers.

The food may be stored by refrigerating or freezing the food, and if desired, the food may be thawed in the container prior to heating.

The method may optionally include adding further ingredients to the food in the container prior to heating. For example, in a preferred embodiment of the invention, the container comprises a pizza pan and the food comprises pizza dough, where it is desirable to add additional ingredients prior to cooking. The lid may be removed from the container prior to heating, or it may remain on the container during heating. If the lid is retained during heating, it is preferably attached to the container such that it forms a seal. The lid may also be vented to provide for moisture loss during or after cooking.

Food may be cooked in the ovenable container by placing food in the container and heating the container for a period sufficient to cook the food. The container is adapted to cook foods at oven temperatures of greater than about 400°F, and preferably up to about 600°F, without generating an objectionable odor, or without any substantial degradation, discoloration, or deformation of the container. The container may be heated in a conventional or microwave oven. After cooking the food, the food may be delivered in the container.

Leftover food may also be stored in the container.

The preparation of food using the method of the present invention results in significant savings as well as new opportunities in the convenience food industry. Specifically, the method allows for: 1 ) reduced labor costs by the elimination of tasks such as folding of delivery boxes and washing of metal cooking pans; 2) reduced contamination potential due to the disposable nature of the container and the reduction in the number of times the food is handled prior to delivery to the consumer; 3) use of higher oven temperatures and combination microwave and conventional, halogen light, or impingement oven technology to provide faster cooking. For example, portable ovens can be used to cook food in the container which is then provided directly to the customer. This will, in turn, allow a broader range of food product offerings which can be packaged and cooked using the method of the present invention.

The method also increases the quality of the food being presented, thus increasing customer satisfaction. Accordingly, it is a feature of the present invention to provide a method of packaging and cooking food in an ovenable container. This, and other features and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. Fig. 1 is a perspective view illustrating one embodiment of the container and lid of the present invention. The method of the present invention provides a number of advantages in that it utilizes an ovenable container which may be heated in a conventional or a microwave oven at high temperatures of greater than 400°F, preferably greater than 450°F and up to 600°F. Because the container may be heated at oven temperatures up to 600°F, the cooking time may be reduced. In addition, where the ovenable container is used in the pizza industry, the method will not only reduce cooking time, but will result in labor savings as it eliminates the need to use special pizza pans which must be washed with detergents, and eliminates the need for separate boxes for delivering the pizza, also providing an environmental advantage. The container may also be heated in a smaller oven than a conventional oven, such as a portable oven.

The ovenable container is preferably formed from a filled composite material containing a filler, fibers, and a binder. Suitable fillers for use in the composite formulation include any organic or inorganic, natural or synthetic filler which will withstand the high temperatures required for using the container. The filler comprises from about 20 to 90% by weight of the filled composite material, and preferably, about 60 to 80% by weight of the filled composite material, and is preferably selected from the group consisting of calcium carbonate, talc, and clay. The fibers in the filled composite material may comprise organic fibers including natural fibers such as cellulose; synthetic fibers such as polyester, nylon, polypropylene, polyethylene, acrylic, aramid, rayon, or polystyrene; inorganic fibers such as glass or carbon fibers, or combinations of natural organic and/or synthetic and/or inorganic fibers. The filled composite material may comprise up to about 40% by weight total fibers, and more preferably, from about 4 to 20% by weight total fibers.

The preferred binder for use in the present invention is a latex formed from at least one soft monomer, at least one hard monomer, or a combination thereof, where the resulting polymer has a glass transition temperature of between 0 and 125°C. The latex also preferably includes a polymerizable emulsion stabilizer, and optionally a molecular weight modifier.

By "soft" monomer, it is meant a monomer whose homopolymer glass transition temperature is less than about room temperature (25°C) as measured by any conventional technique such as dynamic scanning calorimetry. By "hard" monomer, it is meant a monomer whose homopolymer glass transition temperature is greater than about room temperature (25°C) as measured by any conventional technique such as dynamic scanning calorimetry. Monomers falling on or near room temperature (25°C) can be classified as either hard or soft.

The monomer compositions should be controlled such that 1) the final polymer will withstand the high temperatures required for using the container, and 2) the glass transition temperature (Tg) is maintained between about 0 to 125°C, and preferably between about 60 to 90°C. This glass transition temperature can be achieved with homopolymers whose glass transition temperature normally falls within this range when measured by an appropriate method such as dynamic scanning calorimetry. For example, a methyl acrylate homopolymer has a Tg of approximately 8°C. For monomers whose homopolymer falls outside of this range, comonomers must be added such that the Fox equation would reasonably predict a copolymer glass transition temperature in the correct range. A form of the Fox equation is as follows:

[l/(Tg_p)] = Σ[(w_i)/(Tg_i)] in which

Tg_p = the glass transition temperature of the copolymer Wj = the weight percent of a given monomer "i" in the copolymer Tgi = the homopolymer glass transition temperature for a given monomer "i". Care should always be taken when using the Fox equation to do actual measurements of the glass transition temperature of the material as it is known that some monomers, when used in copolymerizations, render copolymers that deviate significantly from Fox predictions. One such example would be vinylidene chloride. The latex used in the present invention is preferably formed from the emulsion polymerization of methyl acrylate, methyl methacrylate, and a molecular weight modifier such as a crosslinking agent. Preferably, the molecular weight modifier comprises glycidyl methacrylate. The latex preferably comprises, based on total monomers, from about 0.1 to 99% by weight methyl acrylate, from about 0.1 to 99% by weight methyl methacrylate, from about 0.1 to 5% by weight of a polymerizable emulsion stabilizer, and from about 0 to 3% by weight of a molecular weight modifier.

The process for making the container of the present invention may be carried out using a variety of techniques including adaptations of a fine pulp molding process, thin wall pulp molding process(with or without after-press), or conventional paper making process followed by dry or wet press forming with heat.

Referring now to Fig. 1, a preferred ovenable container 10 for use in the present invention is shown which includes a base or floor 12 and a generally upstanding surrounding side wall 14 defining an opening for containing food. A flange or peripheral edge portion 16 is formed on the top edge of the sidewalk The container preferably includes a lid 18 as shown which is adapted to be fitted onto the peripheral edge of the sidewalls.

The lid may be adapted to seal the container to maintain freshness of the food during storage and/or delivery. The lid is adapted to be fitted and removed multiple times, e.g., it may be removed during food preparation, it may be kept on during storage, left on or off during cooking, placed on during delivery, taken off for serving and placed back on for left-over storage. If desired, the lid and/or the container may be provided with embossed or printed indicia as desired. The lid may be formed from the same filled composite material as the container body using the methods described above, or it may be formed from a material selected from the group consisting of polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyolefins, paper, paperboard, or molded pulp. It should be appreciated that the lid does not have to be ovenable, i.e., food may be cooked with the lid on or off. The lid may also be provided with slots or perforations as desired for cooking purposes, e.g. to control the quality of the food being cooked within the container and to provide a vent.

The design of the container and lid provides good thermal insulation properties to maintain heat of the cooked food, e.g., during delivery. In addition, the use of a lid formed from the filled composite material or from pulp-molded paper allows controllable absorption of moisture from chilled or heated food, i.e., no appreciable condensation. Further, the compressed container bottom wall allows better heat conduction in an oven. Finally, the container exhibits a low thermal heat transfer rate which allows manual handling of the container shortly after cooking. In addition to the above-mentioned features, the container and lid geometry may be configured to provide a number of other desirable features. For example, the lid may be designed to interlock with the bottom of a second covered pan such that the pans and lids may be stacked for storage or transport. The lid may also be designed to be removed and fitted underneath the container so as to function as a trivet after the food is cooked.

The container and/or lid may also include an optional barrier layer (not shown) to protect food in the container from gas and vapor exchanges within the environment which could lead to loss of freshness or the introduction of an undesirable odor or taste. The barrier layer also functions to prevent grease or oils in the food from penetrating the container as well as provide a release layer for removing food from the container without sticking. A preferred barrier layer for use with the container and/or lid of the present invention is polyethylene terephthalate film. It should be appreciated that Fig. 1 illustrates only one possible configuration of the container. The container may be configured in a wide variety of other shapes and sizes; for example, the container may be rectangular in shape and may include handles on opposite sides to aid in transport of the container, e.g. from an oven. In a preferred method of the present invention, the container is used as a pizza pan. In this method, pizza dough is placed in the pan, the lid is placed on the container, and the container with the dough is stored by refrigerating or freezing. The container may then be sent to a distribution outlet, such as a pizza restaurant, mobile kiosk, or other remote cooking location, where the dough may be thawed or refrigerated in the container until it is ready for cooking. Additional ingredients can then be added to the dough in the container for purposes of preparing a finished pizza, and the pizza can be cooked in an oven. The pizza is preferably cooked at a temperature and time necessary to produce the desired doneness. For example, a pizza may be cooked in an air impingement oven at a temperature of about 450°F in a period of about 8 minutes. The pizza may be cooked in the container at oven temperatures up to 600°F without generating any objectionable odors from the container or the food.

The method of the present invention allows the container to replace metal pans currently in use which must be washed at the end of each work day and which provide an opportunity for product cross-contamination through multiple use. The method of the present invention also allows the use of a combination of microwave and conventional ovens to cook pizza or other food items in a shorter time than is currently possible. The method of the present invention also allows mobile ovens to be used to cook foods. For example, a container packaged with frozen pizza dough may be prepared and cooked at a remote location using a mobile oven which would have previously been difficult due to the large supply of reusable pans required.

After cooking, the pizza may then be served or delivered in the same container to a customer. The customer may then store any leftover pizza in the same container.

The container may also be used to cook a wide variety of other foods including frozen or refrigerated soups, frozen or refrigerated meats, frozen entrees, and frozen or refrigerated casseroles. In each of these instances, the container can be filled with food, sealed with a lid or film, stored, and then cooked and served within the same container.

While the method has been described herein primarily with regard to the preparation of pizza, it should be appreciated that the container may be used to package and cook a variety of foods. For example, the container may be used to cook frozen or refrigerated soups, frozen or refrigerated meats, frozen entrees, and frozen or refrigerated casseroles. In each of these instances, the container can be filled with food, sealed with a lid or film, stored, and then cooked and served within the same container.

While certain representative embodiments and details have been shown for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the methods and apparatus disclosed herein may be made without departing from the scope of the invention, which is defined in the appended claims. What is claimed is:

Claims

1. A method for packaging and cooking food in the same container comprising: a) providing an ovenable container and a lid adapted to fitted on said container; said container comprising a filled composite material containing a filler, a fibrous material, and a binder selected from natural or synthetic latexes and natural or synthetic dispersed polymers; b) placing food in said container; c) placing said lid on said container; d) storing said food in said container; and e) heating said container for a period sufficient to cook said food.

2. The method of claim 1 including adding further ingredients to said food in said container prior to heating.

3. The method of claim 1 wherein storing said food comprises refrigerating or freezing said food.

4. The method of claim 3 including thawing said food in said container prior to heating.

5. The method of claim 1 including removing said lid from said container prior to heating.

6. The method of claim 1 including delivering said food in said container after cooking said food.

7. The method of claim 1 including storing leftover food in said container.

8. The method of claim 1 wherein said container is heated in an oven selected from a conventional oven, microwave oven, or combination oven.

9. The method of claim 8 in which said container is heated at a temperature up to 600°F.

10. The method of claim 1 wherein said container comprises a pizza pan and said food comprises pizza dough.

11. The method of claim 1 in which said lid is adapted to seal said container.

12. The method of claim 1 in which said lid is embossed or printed.

13. The method of claim 1 in which said container comprises a body including a base and surrounding sidewalls defining an opening for containing food therein.

14. The method of claim 14 in which said lid is mounted on the peripheral edge of said sidewalls.

15. A method of cooking food in an ovenable container comprising: a) providing a container comprising a filled composite material containing a filler, a fibrous material, and a binder selected from natural or synthetic latexes and natural or synthetic dispersed polymers; b) placing food in said container; and c) heating said container for a period sufficient to cook said food.

16. The method of claim 15 wherein said container is heated in an oven selected from a conventional oven, microwave oven, or combination oven.

17. The method of claim 15 wherein said container is heated at a temperature up to 600°F.

18. The method of claim 15 wherein said container comprises a pizza pan and said food comprises pizza.

19. The method of claim 15 including delivering said food in said container to a customer.