WO2003035507A1

WO2003035507A1 - Enclosure for heatable food product

Info

Publication number: WO2003035507A1
Application number: PCT/GB2002/004768
Authority: WO
Inventors: Simon Pope; Christopher Pittordou
Original assignee: Mccain Foods (Gb) Limited
Priority date: 2001-10-22
Filing date: 2002-10-22
Publication date: 2003-05-01
Also published as: GB0125346D0; WO2003035507A8

Abstract

The present invention provides an enclosure (10) for pizza, the enclosure (10) being of ovenable material and adapted for exposure to a source of heating energy, in which the enclosure includes a lower surface (11) adapted to support pizza and an upper surface (13) adapted to cover a pizza, the enclosure (10) including one or more openable vents (17, 18, 19, 20, 21) in said lower surface (11), wherein said one or more vents (17, 18, 19, 20, 21) are covered, in use, by a pizza supported on the lower surface (11).

Description

Enclosure for Heatable Food Product

This invention relates to an ovenable enclosure for heating/cooking a food product and particularly to a box for pizza, preferably a box suitable for frozen pizza.

Many different kinds of such heating enclosures are known, some of which comprise the original packaging in which a frozen food product is sold. In that case, the kind of packaging will depend on the heating/cooking medium to be used. For example different kinds of packaging are often required for oven heated and microwave heated products. The former must be adapted to resist considerable external heat radiation yet allow the food product to be heated, whereas the latter is heated indirectly by material within the packaging.

EP-A-0336325 describes a a microwave enclosure having a metallic coating to produce enlianced heating in selected areas of the enclosure, in order to give a fully cooked and 'browned' appearance. It is also known to provide perforations in a section of an enclosure, such that heat can be better transmitted through that part of the enclosure to ensure the product is cooked evenly throughout. WO 99/04638 describes a pizza pan shield which uses this method.

The choice of packaging to be used on a heating enclosure is important because it affects the quality of the resulting food product. The cooking environment in a microwave can be regulated by the packaging because the cooking time can be accurately controlled using the microwave timer and because the energy source ceases at the end of the cooking time. The packaging is chosen to optimise the quality of the cooked product.

It is more difficult to heat or cook oven heated food products consistently because there are many variables which cannot be controlled, and because users have many more options available. For example despite written instructions, a user may not wait for an oven to reach a required temperature, the oven may have an uneven heat distribution, oven temperature control is often rather poor, and cooking time is difficult to control accurately particularly because residual heat will continue to cook the product even if the energy source is turned off.

A problem often arises in oven heated frozen pizza, because of the large thermal mass of the pizza. The uncontrolled cooking environment in the oven frequently results in dryness of the pizza crust and/or burning of the topping. This could be overcome by a heating enclosure which can control the cooking environment more closely, thereby providing a more consistent result. Such an enclosure preferably would be adapted to resist up to 300°C for up to one hour.

According to a first aspect of the present invention there is provided an enclosure for pizza, the enclosure being of ovenable material and adapted for exposure to a source of heating energy, in which the enclosure includes a lower surface adapted to support a pizza and an upper surface adapted to cover a pizza, the enclosure including one or more openable vents in said lower surface, wherein said one or more vents are covered, in use, by a pizza supported on the lower surface. The pizza may be frozen or chilled, and may be part cooked. By covering the vents with the pizza base the possibility of pizza topping displaced from the pizza escaping the enclosure is greatly reduced.

Such an enclosure permits the heating/cooking environment within the enclosure to be closely controlled, and to better ensure that the heated/cooked food product is to the required standard. Naturally, the material of the enclosure should be capable of exposure to heating energy without imparting any flavour or odour taint to pizza in the enclosure. It will be understood that the present invention relates to enclosures for pizza which is to be heated in a thermal oven as opposed to a microwave oven.

The or each vent reduces the build up of moisture on the crust during cooking. This results in a crisper crust for the cooked pizza. The or each vent may be openable, which is to say that they may be temporarily covered, for example to protect the contents of the enclosure during transit and storage. In one embodiment, the lower surface of the enclosure comprises an inner layer having a pre-formed vent or vents therein, and an outer layer which hermetically seals the enclosure for sale and transit, and which is removable just before heating/cooking. The outer layer may, for example, be a film of any conventional and suitable kind.

In a preferred embodiment there are provided a plurality of vents which extend outwardly from a point on the lower surface. In a preferred embodiment the vents extend outwardly from a point substantially at the centre of the lower surface of the enclosure. The vents may comprise a central vent having a plurality of additional vents provided thereabout. The central vent may be of any suitable shape such as, for example, circular. The additional vents may be of any suitable shape. In an alternative embodiment there may be provided a single vent having a central hub portion and a plurality of outer portions extending therefrom.

In one embodiment the vent or vents are preferably configured such that, in use, the ratio of vent area in the lower surface to pizza area supported on the lower surface decreases with increasing radius of the pizza. Taking the example of a circular pizza, it will be understood that at a first radius Rl the pizza will cover an area Al defined by the relationship Al= πRl² . For a second radius R2, R2 being greater than Rl, the area A2 covered by the pizza is equal to πR2². At each radius the vent area VA may be cosidered to be VAl and VA2 and hence the ratio VA2/A2 is less than the ratio VA1/A1.

In an alternative example the vent area may equal the pizza base area over a first radius range and thereafter the ratio of vent area to pizza base area decreases with increasing radius.

The area of the vent or vents in the lower surface may be approximately equal to between 5% to 40% of the area of the pizza contained in the enclosure. More specifically the area of the vent or vents in the lower surface may be approximately equal to between 10% to 30% of the area of the pizza contained in the enclosure. Preferably the area of the vent or vents in the lower surface may be approximately equal to 20% of the area of the pizza contained in the enclosure. In an alternative embodiment the percentages given above may be of the area of the lower surface as opposed to the pizza.

It is also preferable to provide an aperture, in the upper surface of the enclosure. Such an aperture allows the user to see the pizza before cooking, and to inspect the pizza during cooking. This has been found to be an important advantage since users tend to want to see the unheated food product and accordingly will open the enclosure even if instructions require the enclosure to remain closed. The size of the aperture in the upper surface may be approximately equal to between 10% to 50 % of the area of the pizza contained in the enclosure. In an alternative embodiment the size of the aperture in the upper surface may be approximately equal to between 10% to 50 % of the area of the upper surface.

It will be appreciated that the size of the aperture is dependent upon a number of factors including the thickness of the pizza and composition of the pizza topping. In particularly the moisture content of the topping is a factor in the required size of upper aperture. Taking the example a thin crust pizza having a relatively thin topping with a relatively low moisture content, than an aperture sized towards the lower limit mentioned above will typically be required. Alternatively a so called 'deep pan' thick based pizza having a relatively thick topping with a relatively high moisture content will typically require an aperture sized towards the upper limit mentioned above.

The aperture may be openable, which not only allows the user to see the pizza before and during cooking but also permits additional heat transfer to the pizza, resulting in desirable 'browning' of the topping. The upper surface of the enclosure preferably comprises an inner layer having a pre-formed aperture and an outer layer which hermetically seals the enclosure. The outer layer is removed prior to heating.

The enclosure of the invention is preferably close fitting to the pizza, and in particular the inside of the upper surface is spaced from the pizza by a relatively small distance.

Preferably the interior height of the enclosure is not more than about 150% of the thickness of the pizza, and is most preferably in the range 100-150%. In a preferred embodiment the interior height of the enclosure is about equal to 120%> of the thickness of the pizza.

The enclosure may be provided with a metal plate on the inside of said lower surface.

The metal may be of any suitable composition, for example aluminium, copper or steel having a suitable protective coating to avoid e.g. odour taint. The metal plate may comprise a foil sheet of 50 micron thickness, or be relatively smaller in area and have a greater thickness.

The purpose of the metal plate is to provide a highly conductive heat source adapted to promote heat transfer to the centre of the pizza, thereby to improve the taste, texture, smell and flavour of the hot food product.

The preferred size and thickness of the metal plate is selected empirically to suit the degree of additional heat transfer which is required, and will depend to some extent on the mass of the plate, and the nature of the pizza topping.

The vents reduce the build up of moisture on the crust during cooking. This results in a crisper crust. They also aid heat transfer to the metal disc, thereby reducing cooking time.

A typical pizza is approximately circular and contained in an enclosure which is square in plan and close fitting. Preferably the metal plate is circular. It should be centrally positioned to produce the most even cooking.

In a preferred embodiment the vents are positioned around the edge of the metal plate. This results in an even transfer of heat. Preferably the vents are arranged such that they are covered by the pizza when it is in the box. This allows heat transfer to and moisture transfer away from the pizza base . In such an embodiment having a metal plate the vents may be circular. The diameter of the vents is preferably between 0.25 mm and 25 mm, more preferably between 1 mm. and 15 mm. and most preferably between 5 mm. and 10 mm. The vents preferably cover between 1%> and 50%, more preferably between 1%> and 25% and most preferably between 1% and 10%.

In one embodiment the lower surface is provided with a large number of small vents. Alternatively the lower surface may be provided with a small number of large vents.

In another embodiment the vents are positioned across the entire lower surface. The metal plate itself may be vented.

According to a second aspect of the present invention there is provided an enclosure for pizza, the enclosure being of ovenable material and adapted for exposure to a source of heating energy, in which the enclosure includes a lower surface adapted to support a pizza and an upper surface adapted to cover a pizza, the enclosure including a metal plate on the inside of said lower surface and one or more openable vents in said lower surface. The pizza may be frozen or chilled, and may be part cooked.

Other features of the invention will be apparent from the following description of preferred embodiments shown by way of example only in the accompanying drawings in which:

Figure 1 shows a perspective view of an enclosure in accordance with a first embodiment of the present invention;

Figure 2 shows a perspective view of an enclosure in accordance with a second embodiment of the present invention;

Figure 3 shows a perspective view of an enclosure in accordance with a third embodiment of the present invention; and Figure 4 shows a perspective view of an enclosure in accordance with a fourth embodiment of the present invention. Referring firstly to Figure 1 there is shown an enclosure for a pizza comprising a flip-top box 10 of heat resistant taint free board. The box 10 comprises a tray 11 with upstanding sides 12, and a lid 13 with a tuck in flap 14. The box 10 is shallow and adapted to accommodate a frozen pizza. It will be appreciated that the depth of the box 10 is tailored to the thickness of pizza it is intended to contain. Typically the box 10 may have a depth of between approximately 18mm to 30mm. The lid 13 is hinged to the tray 11 along one edge. A suitable material for the box is for example extruded PET coated paper board of an appropriate grade.

The tray 11 is provided with a plurality of apertures 18, 19 extending therethrough. In the embodiment shown the apertures comprise a substantially circular aperture 18 surrounded by a plurality of elongate rectangular apertures 19. As can be seen from Figure 1 the rectangular apertures 19 are disposed radially about the circular aperture 18 so as to provide a stellate aperture configuration. The circular aperture 18 is positioned substantially at the centre of the tray 11 and as such, in use, is aligned with the centre of a pizza supported on the tray 11. It will be noted that the rectangular apertures 19 are dimensioned such that the ends distal to the circular aperture 18 are spaced from the edges of the tray 11 such that, in use, the apertures 18,19 are fully covered by a pizza supported on the tray 11. This has the advantage that should the pizza topping spill from the pizza base during heating it will be unable to escape from the box 10 via the apertures 18, 19.

It will be appreciated that the rectangular apertures 18 are of constant width over their length. Thus the ratio of rectangular aperture 18 area to pizza base area decreases as the radius from the centre of the tray 11 increases for radii grater than that of the central aperture 18. Figure 2 shows an enclosure having the same tray aperture configuration as the enclosure of Figure 1 but without the aperture in the lid 13.

Figure 3 shows an alternative embodiment of a pizza box 10 according to the present invention where features common to the first embodiment are identified with like reference numerals. The tray 11 is again provided with a plurality of apertures 20, 21 arranged in a stellate configuration. The apertures comprise a central aperture 20 having a plurality of additional apertures 21 disposed therearound. The additional apertures 21 are smaller than the central aperture 20.

With reference to Figure 4, there is shown a square flip-top box 10 of a heat resistant taint free board comprises a tray 11 with upstanding sides 12, and a lid 13 with a tuck in flap 14. The box 10 is shallow and adapted to contain a frozen pizza. The lid 13 is hinged to the tray 11 along one edge. A suitable material for the box is for example extruded PET coated paper board of an appropriate grade.

In the base of the tray is a circular aluminium foil disc 16. The disc has a diameter about 30%o of the width of the box 10. A series of vents 17 is punched through the base of the tray around the periphery of the disc.

Within the lid 13 is a central circular aperture 15. The aperture 15 has a diameter about 40% of the width of the box 10.

In use the circular frozen pizza is placed on the tray 11, the lid 13 is closed, and an outer layer of e.g. plastic film is applied to hermetically seal the contents. The outer layer may be for example a clear plastic sleeve, heat sealed along opposite edges and carrying printed product information. The box may include one or more glued flaps in order to further preserve the integrity thereof during transit.

After sale, and immediately before heating/cooking, the outer layer is removed to expose the vents 17,18,19,20,21 and, where appropriate, aperture 15, and the box is inserted unopened into an oven. The pizza is heated/cooked according to pre-printed instructions and when ready is removed from the oven for consumption. As illustrated the box is hinged open, and the sides 12 of the tray 11 may be collapsed to permit ready serving. These sides 12 may, for example, have lines of weakness at the corners.

The inside of the trays 10 may include a metal or metallised layer of foil or other material adapted for direct heating by a source of heating energy. The tray may further include an oil resistant coating or film whereby oil may be added to enhance the heating/cooking process in order to give a desirable mouth feel and texture to the pizza.

Although a circular vent and circular metal plate have been described, such shapes are not essential. Other shapes of vent having an attractive or eye-catching appearance are possible whilst ensuring good product appearance after heating. Other shapes of metal plate are also possible, and a rectangular or square plate may be preferred to avoid excessive wastage of material during blanking. The metal plate is preferably secured to the base of the enclosure by a food compatible adhesive.

The vent and plate may be constituted by a plurality of discrete elements such as an array of holes and metal spots adapted to give the desired appearance to the hot food product.

Claims

1. An enclosure for pizza, the enclosure being of ovenable material and adapted for exposure to a source of heating energy, in which the enclosure includes a lower surface adapted to support a pizza and an upper surface adapted to cover a pizza, the enclosure including one or more openable vents in said lower surface, wherein said one or more vents are covered, in use, by a pizza supported on the lower surface.

2 An enclosure according to claim 1 in which the lower surface of the enclosure comprises an inner layer having one or more pre-formed vents therein, and an outer layer adapted to hermetically close the vent or vents which is removable just prior to heating/cooking.

3. An enclosure as claimed in claim 1 or claim 2, the enclosure being provided with a plurality of vents which extend outwardly from a point on the lower surface.

4. An enclosure as claimed in claim 3 wherein the vents extend outwardly from a point substantially at the centre of the lower surface of the enclosure.

5. An enclosure as claimed in claim 3 or claim 4 wherein the vents comprise a central vent having a plurality of additional vents provided thereabout.

6. An enclosure as claimed as claimed in claim 1 or claim 2 wherein the enclosure is provided with a single vent having a central hub portion and a plurality outer portions extending therefrom.

7. An enclosure as claimed in any preceding claim wherein the vent or vents are configured such that, in use, the ratio of vent area in the lower surface to pizza area supported on the lower surface decreases with increasing radius of the pizza.

8. An enclosure as claimed in any of claims 1 to 6 wherein vent or vents are configured such that the vent area equals the pizza base area over a first radius range and thereafter the ratio of vent area to pizza base area decreases with increasing radius above said first range.

9. An enclosure as claimed in any preceding claim wherein the area of the vent or vents in the lower surface is approximately equal to between 5% to 40%> of the area of the pizza contained in the enclosure.

10. An enclosure as claimed in claim 9 wherein the area of the vent or vents in the lower surface is approximately equal to between 10% to 30% of the area of the pizza contained in the enclosure.

11. An enclosure as claimed in claim 10 wherein the area of the vent or vents in the lower surface is approximately equal to 20% of the area of the pizza contained in the enclosure.

12. An enclosure as claimed in any preceding claim wherein there is provided an aperture in the upper surface of the enclosure.

13. An enclosure as claimed in claim 12 wherein the size of the aperture in the upper surface is approximately equal to between 10% to 50 % of the area of the pizza contained in the enclosure.

14. An enclosure as claimed in claim 12 wherein the size of the aperture in the upper surface is approximately equal to between 10% to 50 % of the area of the upper surface.

15. An enclosure as claimed in any preceding claims wherein a metal plate is provided on the inside of the lower surface of the enclosure.

16. An enclosure as claimed in claim 15 wherein the metal plate comprises a foil sheet having a thickness of about 50 microns.

17. An enclosure as claimed in claim 15 or claim 16 wherein the metal plate is circular.

18. An enclosure as claimed in any of claims 15 to 17 wherein the metal plate is centrally positioned on the lower surface.

19. An enclosure as claimed in any of claims 15 to 18 wherein there are provided a plurality of vents which are positioned around the edge of the metal plate.

20. An enclosure as claimed in any of claims 15 to 19 wherein the metal plate is vented.