WO2006024852A1

WO2006024852A1 - Packaging for food comprising an integrant heating device and a steam generator therfor

Info

Publication number: WO2006024852A1
Application number: PCT/GB2005/003375
Authority: WO
Inventors: Matthew John Searle
Original assignee: Griffyn Service Providers Limited
Priority date: 2004-09-01
Filing date: 2005-09-01
Publication date: 2006-03-09
Also published as: EP1791766A1; GB2418976B; EA200700578A1; GB0419415D0; GB2418976A

Abstract

One embodiment of the invention relates to a steam generator (604) for generating steam, said steam generator comprising: a first chamber (628) adapted to contain a first substance that reacts exothermically with a second substance to generate steam; a second chamber (630) adapted to contain said second substance; a steam outlet (638) for discharging steam from the steam generator; a first frangible barrier (644) between one of said first and second chambers and said steam outlet; a second frangible barrier (664) between said first and second chambers; a first barrier-breaking device (674) operable for breaking said first barrier, thereby to allow steam to pass to the outlet; a second barrier-breaking device (682) positioned within the one chamber and operable for breaking said second barrier to allow said first and second substances to contact one another to react together; wherein said first and second barrier-breaking devices are arranged such that operation of said first barrier-breaking device causes operation of said second barrier-breaking device. Another embodiment relates to food packaging comprising an integrant heating device.

Description

Packaging for food comprising an integrant heating device and a steam generator therefor

The present invention relates to packaging for food comprising an integrant heating device, particularly a heating device adapted to generate and discharge steam. The present invention also provides a steam generator for such packaging.

WO 02/085171 Al discloses a steam generator device having first and second chambers, and walls mutually isolating the two chambers. Reagents which react together to generate steam when in mutual contact are mutually separated by a barrier and disposed in the first chamber. An opening member forms a first opening between the chambers and a second opening through the barrier. Hence the reagents come into contact via the second opening, the reagents react thereby generating steam, and the steam flows through the first opening into the second chamber. The second chamber may contain food, such that the steam generated within the first chamber enters the second chamber to heat the food.

In general, the steam generator of WO 02/085171 Al works satisfactorily, but a problem in some embodiments, where the first chamber is disposed directly beneath the second chamber in use and the steam discharged from the first chamber passes through a short, vertically-extending passageway into the second chamber, is that as one of the reagents in the first chamber becomes exhausted and the reaction slows down, the first chamber begins to cool such that steam therein condenses causing a reduction in pressure. This may have the effect of drawing liquids within the second chamber to reverse-flow downwardly through said short passageway into the first chamber where they may reaccelerate the reaction, resulting in turn in the reheating of the contents of the chamber, and the generation of further steam, thereby causing at least some of said liquids to flow back into the second chamber, entraining a proportion of said reactants or other undesirable materials. This may have an adverse affect on the quality of the food substances in the second chamber.

Accordingly, it is object of the present invention to provide improved packaging for food and other goods, which packaging comprises an integrant heating device.

It is a particular object of the present invention that to provide such packaging which reduces the possibility of undesirable materials migrating into the food.

Further, it is an object of the present invention to provide packaging for food which can be retorted to provide an extended shelf-life. A further object of the present invention is to provide packaging for food comprising an integrant heating device which is more convenient to operate than prior devices.

Another object of the present invention is to provide an improved steam generator for such packaging.

Further objects and advantages of the present invention will be apparent from the following description of the same.

According to one aspect of the present invention therefore there is provided packaging for food comprising an integrant heating device for heating the food, said packaging comprising: a steam generator adapted to generate and discharge steam, said steam generator having a steam outlet; a receptacle adapted to receive an edible substance to be consumed warm, said receptacle having a steam inlet for admitting steam into the receptacle to contact said edible substance; a steam conveying system defining a path for conveying steam from said steam outlet to said steam inlet; wherein said packaging is configured to define an upright orientation, said steam conveying system including a liquid trap that is disposed beneath said steam inlet, and said path comprising a fall from said steam outlet to said steam inlet when in said upright orientation; the arrangement being such that any liquid that enters the steam conveying system from the receptacle is caught in the liquid trap and cannot back-flow up the fall to re-enter the steam generator.

Preferably, said path comprises a run that subtends an angle with said upright of less than about 70°, more preferably less than about 45°, and most preferably less than about 10°.

Advantageously, the steam conveying system may further comprise a one-way valve positioned in said path to resist further the back-flow of liquids along the path to the steam generators. Suitable one-way valves are known to those skilled in the art, including for instance clapper valves, ball valves, poppet valves and duck-bill valves.

In accordance with the present invention, therefore, the inclusion of a liquid trap in the steam path between the steam generator and the receptacle, in combination with a fall or grade in the path from the steam generator to the liquid trap, means that any liquid, such as sauces or cook-out juices, entering the steam conveying system from the receptacle, whether as a result of a reduced pressure in the steam generator or otherwise, is trapped in the liquid trap and cannot flow back up the fall to the steam generator.

Where present, said one-way valve may be suitably positioned in the steam outlet from the steam generator, or at the entrance to the liquid trap.

In some embodiments, said steam conveying system may comprise a duct from the steam outlet to the steam inlet, and the liquid trap may comprise a chamber having enlarged dimensions as compared with the dimensions of the duct. Said duct may communicate with an upper end of the chamber in the upright orientation, so that steam can pass freely over any liquid trapped in the liquid trap. It will be appreciated that by the term "liquid trap" is meant a trap for liquids entering the steam conveying system from the receptacle; the liquid trap is not configured in the manner of a conventional "water trap" to prevent gases entering the receptacle.

Suitably, the steam inlet to the receptacle may comprise a diffuser. Said inlet may be disposed at or towards the lower end of the receptacle in said upright orientation. In some embodiments the food or other substance within the receptacle may comprise a liquid component such, for example, as a sauce, and in some embodiments an amount of liquid matter, such as juices, may be cooked out of the food during heating. In such embodiments, the steam inlet is suitably positioned above the bottom of the receptacle above the level or anticipated level of such liquids.

Suitably, the receptacle may comprise an exhaust for said steam.

In some embodiments, the receptacle may comprise an upper rim, and said exhaust may comprise one or more grooves formed in said rim.

Said steam generator may be adapted to generate heat by contacting a first substance that reacts exothermically with water with a second aqueous substance that is adapted to react exothermically with said first substance, and using the heat generated thereby to evaporate water as steam. In some embodiments, the steam used for warming the food or other substance in the receptacle may be generated from the water component of the second aqueous substance. Alternatively, steam generated by the reaction may be used to heat a separate body of water to produce steam for heating the food or other materials.

In some embodiments, the steam generator may comprise a first chamber adapted to contain said first substance, a second chamber adapted to contain said aqueous substance, a frangible barrier between the first and second chambers and a selectively operable barrier-breaking device for breaking said barrier to allow such first and second substances to contact one another to react together to cause the water component of the aqueous substance to evaporate as steam. The first chamber may be disposed beneath the second chamber in the upright orientation, and the second aqueous substance may be fluent, such that upon breaking the barrier the second aqueous substance is allowed to flow under gravity into the first chamber to react reliably with the first substance.

The steam outlet may be disposed above the second chamber in the upright orientation, such that steam generated by the reaction between the first and second substances passes upwardly through the second chamber before entering the steam conveying system. This has the advantage that residual water within the second chamber may serve to remove unwanted reactant dust or other matter from the steam before it enters the steam conveying system.

In a different aspect of the present invention there is provided a steam generator for generating steam, particularly for use in packaging comprising an integrant heating device, said steam generator comprising: a first chamber adapted to contain a first substance that reacts exothermically with water; a second chamber adapted to contain a second aqueous substance which is adapted to react exothermically with said first substance to generate heat to cause water to evaporate; a steam outlet for discharging steam from the steam generator; a first frangible barrier between one of said first and second chambers and said steam outlet; a second frangible barrier between the first and second chambers; a first barrier-breaking device operable for breaking the first barrier, thereby to allow steam to pass to the outlet; a second barrier-breaking device positioned within the one chamber and operable for breaking said second barrier to allow said first and second substances to contact one another to react; wherein said first and second barrier-breaking devices are arranged such that operation of one of said barrier-breaking devices causes operation of the other barrier- breaking device. Advantageously, the first barrier may serve to seal the one chamber from the steam outlet. Said second barrier may serve to seal the first and second chambers from each other.

In some embodiments, said steam generator may comprise a closed vessel having an internal lumen, said first and second chambers being defined by first and second regions respectively of said lumen. Said second barrier may extend across the lumen to divide the first and second chambers from one another; the second barrier may extend across the lumen to divide the one chamber from the steam outlet.

Suitably, said steam outlet may be formed in the vessel, and advantageously the vessel may be completely sealed, apart from said steam outlet. In this manner, a retortable steam generator is provided by the present invention.

Said first barrier-breaking device may comprise a first barrier engaging member disposed juxtaposed said first barrier, which first member is movable against the first barrier for breaking the same, and a selectively operable pusher for pushing the first member against the first barrier. Typically, said pusher may be manually operable.

In some embodiments, the first barrier engaging member may be connected to the pusher.

Suitably, the vessel may comprise a wall portion juxtaposed the first barrier, said pusher being provided in the wall portion. Said wall portion may be flexible such that it can be flexed towards the first barrier for pushing the first barrier engaging member against the first barrier.

Suitably, said first barrier may comprise a flexible membrane such as a sealing film, and the first barrier engaging member may be adapted to rupture said membrane when urged against the same. For instance said first barrier engaging member may be adapted to pierce the first membrane.

In some embodiments, the second barrier-breaking device may comprise a second barrier engaging member disposed within said one chamber intermediate said first and second barriers, said second member being movable against the second barrier for breaking the same. The second barrier engaging member may be configured to be pushed against the second barrier by the first barrier engaging member when the latter is pushed against the first barrier. Conveniently, therefore operation of the first barrier breaking device causes concomitant operation of the second barrier-breaking device. Said second barrier may comprise a flexible membrane, and said second barrier engaging member may be adapted to rupture the membrane.

Conveniently, the vessel may be configured to define an upright orientation, said first and second regions being provided in lower and upper regions of the vessel respectively; said second substance may be fluent, such that upon breaking the second barrier, the second fluent substance is allowed to flow under gravity into the first chamber to react with the first substance.

The steam outlet may be provided above the second region, with the first barrier being positioned between the second chamber and the outlet. In yet another aspect of the present invention, there is provided food packaging comprising an integrant heating device for heating the food, said packaging comprising: a container comprising or accommodating a receptacle that is adapted to receive an edible substance to be consumed warm, a selectively operable steam generator adapted to generate and discharge steam and a steam conveying system for conveying steam from the steam generator to the interior of the receptacle for heating said edible substance therein; said container having an opening and a sealing rim that extends around said opening, said sealing rim being adapted to mate with a closure for hermetically sealing said container; said steam generator having an actuator that is only accessible via said opening; and said receptacle comprising an exhaust for steam and communication with said opening; the arrangement being such that the closure must be at least partially removed from the sealing rim to access the actuator, thereby venting the exhaust to the atmosphere. In accordance with this aspect of the present invention, it will be appreciated that the closure for the food packaging constitutes a tamper-evident closure, since the actuator cannot be operated without at least partially removing the closure. Further, since the receptacle is vented to the atmosphere upon opening the closure to access the actuator, it is impossible to operate the steam generator without first venting the receptacle. In this way, an undesirable build-up of pressure within a closed receptacle is avoided.

Suitably, said sealing rim may be adapted to mate with a film closure for forming an hermetic seal. In some embodiments, the container may be configured to define an upright orientation and may comprise two adjacent, open-topped wells, one of said wells comprising or accommodating said receptacle, and the other accommodating the steam generator; the actuator of the steam generator being accessible via the open top of said other well; and said sealing rim forming a closed figure that extends round said wells such that, when fitted, said closure extends over and seals the open tops of both wells. In this way, the packaging according to the present invention may be completely sealed and thus made tamper-proof and retortable using a single closure.

Said container may further comprise a dividing rim that extends between the wells, said dividing rim being substantially co-planar with the sealing rim and being formed with one or more channels extending between the two wells, thereby serving to vent the receptacle when the closure is removed from the other well.

Said closure may comprise a sealing film that can be sealed to the sealing rim and said dividing rim and, whilst remaining in position around said one well, can be peeled back from the sealing rim round the other well to expose the actuator and desirably and unavoidably to vent the one well via said one or more channels.

Suitably, the container may comprise an assembly, which assembly comprises a first part defining said first and second wells, said sealing rim and said dividing rim, said first part being formed with a slot between said wells, which slot extends below said one or more channels, and a second part comprising a wall portion configured to close the open top of said other well beneath the one or more channels formed in the dividing rim, a diffuser portion configured to extend across the interior of the one well towards its lower end and a connecting portion that extends between said wall portion and said diffuser portion and defines a duct for steam between the other well beneath the wall portion, through said slot to the one well beneath the diffuser portion.

Advantageously, said wall portion may comprise said actuator for the steam generator. Preferably, the wall portion is sealed to open top of the other well. In this way, the steam generator may be completely enshrouded within the first and second parts for protection. Said first part may be configured to cooperate with said connecting portion of the second part to form said duct; conveniently the connecting portion may be clipped or otherwise joined to the first part. Preferably said diffuser portion is spaced from the bottom of the one well to form a liquid trap therebetween.

Following is a descnption by way of example only with reference to the accompanying drawmgs of embodiments of the present invention. In the drawings:

FIG. 1 is an isometnc view of packaging accordmg to a first embodiment of the present mvention;

FIG. 2 is a longitudinal section of the packaging of FIG. 1;

FIG. 3 is a plan view of the packaging of FIG. 1 ; FIG. 4 is a first cross-section of the packaging of FIG. 1;

FIG. 5 is a second cross-section of the packaging of FIG. 1;

FIG. 6 is an isometnc view of a base component of the packaging of FIG. 1;

FIG. 7 is a longitudinal section of an upper body component of the packaging of FIG. 1; FIG. 8 is a first cross-sectional view of the upper component of FIG. 7;

FIG. 9 is a second cross-sectional view of the upper component of FIG. 7;

FIG. 10 is an isometnc view of a barrier breaking member of the packaging of FIG.

•l;

FIG. 11 is a plan view of packaging according to a second embodiment of the present invention,

FIG. 12 is a cross-sectional side view of the packaging of FIG. 11;

FIG 13 is a schematic side view of the packaging of FIGS. 11 and 12;

FIG 14 is a cross sectional side view of a steam generator according to an embodiment of the present invention, FIG 15 is a plan view of the steam generator of FIG. 14;

FIG 16 is a cross sectional end view of the steam generator of FIG 14;

FIG 17 is a side elevation of packaging according to another embodiment of the present invention,

FIG 18 is a plan view of the packaging depicted in FIG 17 in a sealed configuration,

FIG 19 is another plan view of the packaging of FIG 17 in an unsealed configuration,

FIG 20 is a cross-sectional elevation along the line A--A of FIG 19, FIG. 21 is an isometric cross-sectional view corresponding to FIG. 20;

FIG. 22 is a side elevation of one component of the packaging depicted in FIG. 17;

FIG. 23 is a top perspective view of the component depicted in FIG. 22;

FIG. 24 is a perspective view of the underneath of the component depicted in FIG. 22;

FIG. 25 is a side elevation of another component of the packaging depicted in FIG. 17;

FIG. 26 is a perspective view of the component depicted in FIG. 25;

FIG. 27 is a plan view of the component depicted in FIG. 25; and FIGS 28a to 28c are plan, isometric and side elevations, respectively, of an internal component of the packaging depicted in FIG. 17.

Food packaging according to a first embodiment of the present invention comprises a first base component 10 and a second upper body component 20, each of which components is moulded from a thermoplastic synthetic resin material, preferably polypropylene. The two components 10, 20 are configured to mate with one another to form an assembly as shown in FIGS. 2, 4 and 5.

As best seen in FIG. 6., the base component 10 comprises a flat bottom wall 32, an upstanding side wall 34 and a top wall 36, which walls 32, 34, 36 enclose a chamber 38 that is adapted to accommodate a first substance which reacts exothermically with water as described in more detail below.

The bottom wall 32 is adapted to stand on a flat surface for supporting the packaging stably thereon. The packaging is therefore oriented, or configured, to define a natural upright orientation.

The bottom wall 32 extends outwardly slightly beyond the upstanding sidewall 34 to form a lower protruding rim 40.

At one end, the first component 10 comprises an upstanding, generally cylindrical well portion 42. Said well portion 42 has a hollow interior 43 which communicates with said chamber 38.

Said well portion 42 comprises a first lower section 44 of substantially constant internal diameter and an upper section 45 of somewhat increased internal diameter. The well portion 42 is stepped at 46 between the first and sections 44, 45, and the enlarged upper section 45 is further rebated above said step 46 to form a further annular shoulder 47. The upper section 45 of the well portion 42 is formed with a rectangular slot 50 as best shown in FIG. 6., which slot 50 faces the other end of the first base portion 10. Said slot 50 extends downwardly from the upper extremity of the well portion 42 to the step 46 between the first and second sections 44, 45. At its other end, the base portion 10 comprises an upstanding open-top hollow cylinder 54 which, as best seen in FIG. 2, is closed at its lower end by the top wall 36 of the base component 10. Said cylinder 54 forms a liquid trap which is described in more detail below and does not communicate with the chamber 38.

Said cylinder 54 is provided with a slot 56 as best seen in FIG. 8 which extends downwardly from the upper extremity of the cylinder 54 to a point intermediate said upper extremity and the top wall 36 of the base component 10.

Intermediate said well portion 42 and said upstanding cylinder 54, the base component 10 comprises a generally triangular shaped ridge 60 having a longitudinally accurate upper surface 62, which upper surface 62 extends between the lower end of the slot 50 formed in the well portion 42 and the lower end of the slot 56 formed in the cylinder 54.

The lateral edges 64 of said upper surface 62 are suitably adapted for engaging the upper body component of the packaging as described in more detail below. For example, said lateral edges 64 may protrude slightly to each side of the ridge 60 to form a snap-fit engagement with said upper body portion 10.

Said upper wall 36 is formed with strengthening ribs 70 to each side of said ridge 60 to strengthen said chamber 38 against flexing or distortion in use.

As shown in Fig. 1 , said upper body component 20 comprises a bowl-shaped receptacle portion 80, a protruding extension portion 82, and a depending skirt portion 84. Said skirt portion 84 is shaped to form a close fit round the upstanding sidewall portion 34 of the first base portion 10, and has a bottom end 85 that is adapted to abut the protruding lower rim 40.

Said receptacle portion 80 and extension portion 82 define a substantially continuous, flat upper surface 90, including a rim portion 91 that extends round the upper end of the bowl portion 80.

As best seen in FIGS. 1 and 7, the extension portion 82 comprises a depending cylindrical plug portion 94 that is spaced from the skirt portion 84. Said plug portion 94 is configured to form a close fit within the enlarged upper section 45 of the well portion 42 of the base component 10 as shown in FIGS. 2 and 5. Said plug portion 94 has a lower end 95 that is configured to engage said step 46.

Intermediate said upper surface 90 and said lower end 95, the plug portion 94 comprises a disc-shaped, flexible wall portion 96 that extends across the interior of the plug portion 94 to close the same. Circumjacent the flexible wall portion 96, the outer surface of the plug portion 94 is formed with a small step for engagement with said annular shoulder 97.

The generally circular flexible wall portion 96 comprises a central button member 98 which serves as an actuator as described in more detail below. As best seen in FIG. 2, the plug portion 94 closes an upper part of the slot 50 when the first and second components are assembled together, leaving an opening beneath the disc-shaped flexible wall portion 96, above the step 46.

As best seen in FIG. 3, the upper surface 90 of the upper body component 20 comprises a shallow groove 93 that extends between the receptacle portion 80 and the interior of the recessed plug portion 94 for venting the receptacle portion 80 in the manner described below in more detail.

The receptacle portion 80 has an underside 81 which carries two substantially uniformly spaced, longitudinally extending, arcuate ribs 100 as best seen in FIGS. 7-9. Said ribs define an elongate channel 101 beneath the bowl portion 80. The spacing between the ribs 100 is substantially the same, or slightly greater, than the lateral spacing of the two lateral edges 64 of the ridge 62 formed on the base component 10, and the extremities of the ribs 100 may be formed with suitable engaging means (not shown) for engaging said edges 64 to form a snap-fit therewith as mentioned above. The upper surface 62 of the ridge 60 therefore serves to close the channel 101 defined by the ribs 100. Juxtaposed said upstanding cylinder 54, as shown in Fig. 8, the underside 81 of the receptacle portion 80 carries a corresponding depending cylinder 104 that is adapted to mate with said upstanding cylinder 54. As best seen in FIG. 8, the ribs 100 are joined to said depending cylinder 104, which cylinder 104 is open at 105 such that the channel 101 communicates with the interior of said cylinder 104. When the upper body and base components 20, 10 are assembled, the opening 105 formed in the depending cylinder 104 registers with the slot 56 formed in said upstanding cylinder 54. Similarly, juxtaposed the well portion 42, the ribs 100 are spaced to either side of the slot 50 formed in the upper section 45 of said well portion 42 to allow said channel 101 to communicate with the well portion 42 beneath the closure constituted by said plug portion 94 and flexible wall portion

96. In this way, the interior of the well portion 42 communicates with the interior of the fitted cylinders 54, 104 via the channel 101 between the ribs 100, the underside 81 of the receptacle portion 80 and the upper surface 62 of the ridge 60. Within the region defined by the depending cylinder 104, the receptacle portion 80 is perforated by plurality of holes 106.

As mentioned above, the chamber 38 is adapted to accommodate a first substance that reacts exothermically with water. Preferably said first substance comprises quicklime

(calcium oxide). Alternative substances will, however, be apparent to those skilled in the art including, for instance, other alkaline earth metal oxides, potassium permanganate, glycerine, or super-reactive metal alloys which react exothermically, such for example as magnesium-iron alloys that react exothermically with saline solution.

As shown in Fig. 2, said chamber 38 is sealed by means of a breakable membrane

110 that extends across the opening between the chamber 38 and the upstanding well portion 42. Said membrane 110 prevents the ingress of water or moisture before use which would bring about premature slaking of said quicklime.

Above said membrane 110, the well portion 42 defines a second chamber 112 which is sealed at its upper end by a second membrane 1 14 that extends across the interior of the well portion 42 below the level of the slot 50 where the lower section 44 meets the upper section 45. Said second membrane 114 is disposed in contact with, or closely adjacent the button member 98 on the flexible wall portion 96.

Said second chamber 1 12 contains water or another fluent aqueous substance that is adapted to react exothermically with the first substance contained within the first chamber

38. Said second chamber 112 further accommodates a barrier breaking device 120 as best shown in FIG. 10.

Said breaking member 120 comprises a narrow depending stem portion 122 and an enlarged head portion 124 comprising a spider 125 that is adapted to engage slidingly with the interior surface of the lower section 44 of the well portion 42. Said breaking member 120 is disposed freely within the second chamber 1 12, but is located by the head portion

124 to prevent substantial sideways movement and, when supported by the first member

1 10, the head portion 124 contacts or is disposed closely adjacent to the second upper membrane 114. The lower end of the stem portion 122 is configured for rupturing the lower membrane 110 during operation of the packaging as described below.

Similarly, the button member 98 formed on the flexible wall portion 96 is configured for rupturing the upper membrane 114. In use, food or any other substance to be heated is placed within the receptacle portion 80 of the body component 20. Said food may be sealed within the receptacle portion 80 by means of a suitable closure fitted to the rim 91. For example, the receptacle portion 80 may be sealed by means of a sealing film that extends over and is joined sealingly to the upper surface 90 of the upper body component 20. When it is desired to heat the food or other substance received within the receptacle portion 80, the sealing film is peeled back from the extension portion 82 of the upper body component 20 to reveal the button member 98. By breaking a part of the seal between the sealing film and the upper surface 90 of the upper body portion 20, the interior of the receptacle 80 is thereby vented to the atmosphere via the groove 93. The user then pushes downwardly on the button member 98 which is allowed to flex downwardly owing to the flexibility of the flexible wall portion 96. The button member 98 is thereby urged downwardly against the upper membrane 1 14 eventually causing said membrane 114 to rupture. Simultaneously, the downward movement of the button member 98 forces the breaking member 120 disposed within said second chamber 1 12 also to move downwardly against the lower membrane 110. Continued downward movement of said breaking member 120 eventually causes the first lower membrane 1 10 to rupture, releasing the water or other aqueous substance in the second chamber 1 12 to flow under gravity into the first chamber 38 where it contacts the first substance.

As mentioned above, the first substance reacts exothermically with water, and as a result the water or the water component of the aqueous substance is heated. Sufficient heat is generated by the reaction to evaporate the water as steam.

Steam thus produced rises upwardly through the ruptured first membrane 110, and through the ruptured second membrane 1 14 where it enters the space between the second membrane 1 14 and the flexible wall portion 96. The steam exits said space via the slot 50 formed in the upper section 45 of the well portion 42 and flows into the channel 101 between the ribs 100.

The steam exits the channel 101 through the slot 56 formed in the upstanding cylinder 54 and enters the interior of the depending cylinder 104. From there, the steam is able to enter the receptacle portion 80 to contact the food or other substance therein via the openings 106.

In this way, the steam generated by the reaction between water and the first substance is brought into contact with the food or other substance in the receptacle portion 180 to heat the same. Excess pressure within the receptacle portion 80 is released via the groove 93.

After a few minutes, the food is warmed sufficiently for it to be ready for consumption. At this time, the remainder of the sealing film (not shown) may be peeled away from the upper surface 90 of the upper body component 20, allowing the food to be consumed directly from the receptacle portion 80.

In use, some liquid matter, such as a sauce component or juice from the food substance, may flow back from the receptacle portion 80 through the apertures 106 into the depending cylinder 104. Such liquid matter becomes trapped within the upstanding cylinder 54 and cannot backflow into the channel 101. The profile of the channel 101 between the slots 50 and 56 includes a fall as best shown in FIG. 2 which further reduces the possibility of any unwanted matter flowing back up the channel 101 into the steam generator.

In some embodiments a one-way valve (not shown) may be inserted in the steam path between the steam generator and the receptacle portion 80, for instance in one or other of said apertures 50, 56. A clapper valve would be suitable for this purpose to allow steam to pass from the steam generator into the receptacle 80, but to prevent the reverse flow of liquids in the steam path.

Another embodiment of packaging for food in accordance with the present invention is illustrated in accompanying FIGS. 1 1 to 13. The packaging according to the second embodiment comprises two gas impermeable components 200, 300. A first component 200 is configured to define an inherent upright orientation as shown in FIGS. 12 and 13 and comprises a container which is shaped to provide two interconnected, adjacent wells 202, 204. Each of said wells 202, 204 has a substantially flat base 205, 206 respectively, upon which the packaging may stand stably on a flat surface.

Each of said components 200, 300 is preferably vacuum-formed as a respective single piece from a suitable thermoplastic synthetic resin material such, for example, as polypropylene. In an alternative embodiment at least the first component 200 may be pressed from a sheet of aluminium.

Said first component 200 further comprises a substantially flat upper rim 208 which extends completely round the two wells 202, 204 and a dividing rim 209 that extends between the two wells.

One of the wells 202 comprises four interconnected side wall portions 210-213 which each extend upwardly from the base 205 to the upper rim 208 to define a receptacle that is adapted to receive food or any other edible substance to be consumed warm.

The other well 204, which is disposed juxtaposed one of the side walls 212 of the one well 202, also comprises four side walls 214-217 which extend upwardly from the respective base 206 to the upper rim 208. The four side walls 214-217 of the other well 204 as shown in FIGS. 12 and 13 are shaped to provide a first lower section 218, an intermediate section 219 that is wider than the lower section 218 to form a peripheral step 220 and a third upper section 221 that is wider than the intermediate section 219 to form a second peripheral step 222.

The one side wall 212 of the one well 202 and the side wall 214 of the other well 204 that is disposed closest to said one well 202 meet at their upper ends and are shaped to define a slot 228 extending from the dividing rim 209 between the two wells 202, 204 substantially to the level of the second peripheral step 222. Said dividing rim 209 is provided with two small grooves 230 to each side of the slot 228 to provide a vent between the interior of the receptacle provided by the one well 202 and the other well 204.

Juxtaposed said slot 228, the one wall 212 of the first well 202 is rebated to form a vertically extending channel 234. Said rebate extends from the level of the second peripheral step 222 of the second well 204 to the base 205 of the first well 202. By

"vertically extending" it is not meant that the channel must necessarily be upright, but that the longitudinal direction of said channel 234 includes a vertical component. In particular, said channel 234 may be inclined at an angle to the vertical. Preferably, the vertically extending channel 234 may subtend an angle with the vertical of less than 70°, more preferably less than 45° and most preferably less than 20 or 10°. As described in more detail below, the channel 234 provides a fall or grade in a steam path provided between the first and second wells 202, 204. The second component 300 of the packaging according to this embodiment of the invention comprises a closure portion 301 for the second well 204, a diffuser portion 310 that is configured to be inserted in the receptacle defined by the first well 202 and an interconnecting cover strip 320. The diffuser portion comprises a rectilinear perforated plate that is adapted to be supported at a position as shown in FIGS. 12 and 13 that spaced from the base 205 of the one well 202. The base 205 and diffuser portion 310 thus define a chamber 311 beneath the plate which serves as a liquid trap, as described in more detail below. Said plate may be supported in a peripheral groove 312 formed in the inner surface of the walls 210-213 of the first well 202.

The closure portion 301 comprises a central flexible wall portion 302 and is configured to be sealed in the upper open end of the second well 204 at a position above the second peripheral step 222, but below the interconnecting grooves 230. In some embodiments, the closure portion 301 may be welded to the periphery of the second well 204.

Said flexible well portion 302 carries a first depending barrier breaking member 304 as described in more detail below.

Said cover strip 320 is shaped and configured to extend from the closure portion 301, through said slot 228 to an edge of the diffuser portion 310. Between the slot 228 and the diffuser portion 310, the cover strip 320 runs closely adjacent to the rebated channel 234 formed in said one wall 212 to cover said channel 234.

Said cover strip 234 and said one wall 212 may be formed at each edge of the channel with mutually cooperating engaging formations or the like to provide a snap fit between the one wall and the cover strip 234. Where the cover strip 320 extends through the slot 228, it is spaced from the bottom of the slot as best shown in FIG. 13 so that the interior of the second well 204 can communicate with the chamber 31 1 beneath the diffuser portion 310 via the slot 228 and the channel 234.

In some embodiments, a one-way valve such as a clapper valve may be inserted in said channel 234. Said one-way valve may for example be installed at the point where said channel 234 opens into said chamber 31 1. Alternatively the valve may be fitted in said slot 228. The lower section 218 of the second well 204 contains a first substance that reacts exothermically with water. Various suitable substances are mentioned above, but a preferred substance is quicklime.

The lower section 218 is sealed with a membrane barrier 340 that is joined sealingly to the first peripheral step 220 between the lower and intermediate sections 218, 219 of the second well 204.

Said intermediate section 219 contains water or another fluent aqueous substance that is suitable for use in food packaging. For instance, the aqueous substance within the intermediate section 219 may include edible flavourings, colourings, or the like. Said intermediate section 219 is sealed by a second membrane 342 which is joined sealingly to the second peripheral step 222 between the intermediate and upper sections 219, 221, below the level of the slot 228 communicating with the channel 234.

Said intermediate section 209 further contains a second membrane breaking member 344. Said second membrane breaking member 344 is shown schematically in FIGS. 12 and 13; a member similar to the breaking member 120 described above in connection with the first embodiment of the present invention may be used. Thus, the second membrane breaking member 344 may comprise a spider for locating the membrane breaking member 344 stably within the intermediate section 219, whilst allowing movement of the membrane breaking member 344 in the vertical direction. The membrane breaking member 344 is supported on the first membrane 340 and is disposed closely adjacent or in contact with the second membrane 342. The part of the second membrane breaking member 344 in contact with the first membrane 340 is configured to pierce the first membrane 340 when it is urged downwardly against said membrane.

The first membrane breaking member 304 carried by the flexible wall portion 302 is disposed closely adjacent or in contact with the second membrane 342 and is configured to pierce that membrane when it is urged downwardly.

In use, food or another edible substance is received within the receptacle defined by the first well 202, said food or edible substance being supported by the diffuser portion 310 of the second component. The entire container is hermetically sealed by a sealing film 400 that is joined sealingly to said upper rim 208 continuously round the first and second wells 202, 204.

Said sealing film 400 is also joined sealingly to the dividing rim 209, except at the grooves 230 which therefore provide communication between the interior of the receptacle beneath the sealing film 400 and the second well 204 above the closure portion 301.

When it is desired to warm the food or other edible substance within the receptacle of the first well 202, the sealing film 400 may be peeled back from the second well 202 to reveal the closure portion 301. By breaking the seal between the sealing film 400 and the upper rim 208 round the second well 204, the grooves 230 are opened to the atmosphere, thereby venting the interior of the receptacle provided by the first well 202.

The user then presses downwardly on the flexible wall portion 302, causing the first membrane breaking member 304 to move downwardly against the second membrane 342. Since the first membrane breaking member 304 is initially disposed closely adjacent or in contact with said second membrane 342, and the second membrane breaking member 344 within the intermediate section 219 is also disposed closely adjacent or in contact with said second membrane 342, upon such downward movement, the first membrane breaking member 304 pushes against the second membrane breaking member 344 causing the latter to push downwardly on the first membrane 340. Continued downward movement of the flexible wall portion 302 ultimately causes the first member breaking member 304 to rupture the second membrane 342, and the second membrane breaking member 344 to rupture the first membrane 340, allowing the water or other aqueous substance provided within the intermediate section 219 to fall under gravity into the lower section 218 where it contacts the first substance causing an exothermic reaction.

The heat generated by said exothermic reaction evaporates the water or water component of the aqueous substance producing steam which then rises up through the ruptured first and second membranes 340, 342 into the upper section 221 of the second well 204. The steam passes out of said upper section through the slot 228 beneath the cover strip 320 into the channel 234.

The steam then passes down the grade defined by the channel 234 into the chamber 31 1 provided beneath the diffuser portion 310 of the second component.

Finally, the steam is able to pass upwardly into the receptacle of the first well 202 through the perforations provided in the diffuser component 310 where it contacts and heats the food or other edible substance therein.

The steam within the first well 202 is vented to the atmosphere via the grooves 230 provided in the dividing rim 209. After a few minutes, the food or other edible substance within the first well 202 is warmed sufficiently for it to be consumed, and at that time the remainder of the sealing film 400 may be peeled back from the upper πm 208 completely exposing the receptacle of the first well 202 from which the food or other edible substance may be consumed directly It will be appreciated that since the first component of the packaging accordmg to this embodiment of the mvention is formed as a single piece, the sealing film 400 which extends over the entire upper πm 208 of the first component serves to completely seal the packaging Accordingly, the packaging may be retorted in a conventional manner to provide a product with an extended shelf life The sealing film 400 over the receptacle and actuator provided by the flexible wall portion 302 provides a means of indicating whether or not the packaging has been tampered with before use

Further, by removmg the sealing film 400 from at least the second well 204, the first well 202 is reliably vented via the grooves 230 formed in the dividing πm 209, with the result that the packaging cannot be operated to produce steam without providing suitable exhaust means for releasing steam from the receptacle

As shown m FIG 12, the packaging may suitably compπse an outer carton 402 of an insulating mateπal such, for example, as cardboard or the like, so as to avoid the πsk of the user contactmg a hot surface Such an outer carton 402 may be especially desirable when the first component 200 is made of metal such as aluminium

FIGS 14 - 16 show another steam generator 500 in accordance with the present invention Said steam generator compπses a generally rectilinear vessel 504 having a base 506 and four upstanding side walls 514-517

At its upper extremity, 505, the vessel 504 compπses a top wall 507 having a flexible centre portion 508 which serves as a pusher for actuating the steam generator as descnbed in more detail below

The walls 514-517, with the base 506 and top wall 507, define an internal lumen 510 that is sub-divided into three sections, namely a lower section 518, an intermediate section 519 and an upper section 521 The lower and intermediate sections 518, 519 are separated by an internal peπpheral ledge 520, which carπes a lower, liquid-tight, breakable membrane 540 thereon

The intermediate and upper sections 519, 521 are likewise divided from one another by an internal, inwardly protruding peripheral shelf 522, defining a central opening 523 that is closed with an upper breakable membrane 524. The upper membrane 542 is sealed to the peripheral shelf 522 such that the lower and intermediate sections 518, 519 are sealed in a substantially air tight manner by said membrane 542 and by the base 506 and side walls 514-517 of the vessel 504. Said intermediate section 519 accommodates a membrane breaking device 544 compπsing a central body portion 545 and a spider 546. Said central body portion 545 is dimensioned to form a fairly close fit between the upper and lower membranes 540-542, and the spider 546 is configured to locate the membrane breaking device 544 within the intermediate section 519, in particular to prevent substantial sidewise movement of the device 544 within said intermediate section 519. Alternatively the spider may be joined or formed integrally with the side walls 514-517 of the vessel 504 and may be sufficiently flexible to allow the body portion 545 to be moved downwardly against the lower membrane 540 as descπbed below.

Said central body portion 544 is adapted to rupture the lower membrane 540 when it is urged downwards against said membrane.

The flexible central portion 508 of the top wall 507 carries a depending membrane breaking member 550 which is adapted to rupture the upper membrane 542 when it is urged downwardly against the upper membrane 542.

The membrane breaking member 550 is positioned proximate the membrane breaking device 545 such that, upon downward movement, the membrane breakmg member 550 pushes agamst the membrane breaking device 545 such that both the member 550 and the device 545 move downwardly simultaneously to break their respective membranes 542, 540

Adjacent one side wall 516, the vessel 504 carries an extension portion 552 defining an internal flue 554 that communicates with said upper section 521 As best seen in FIG 14, the top wall 507 of the vessel 504 is joined to the extension portion 552 to close the flue portion 554

Said extension portion comprises one or more, preferably two, substantially horizontally extending steam outlet pipes 560 which define respective steam outlet conduits 561 in communication with said flue portion 554

The lower section 518 of the lumen 510 accommodates a first substance of the kind described in more detail above which is adapted to react exothermically with water, said intermediate section 519 contains water or another fluent aqueous substance, such, for example, an aqueous solution of flavourings, colourings or the like. Said first substance is preferably quick lime (calcium oxide), but may be selected from any suitable alternative materials as described above.

In use, a user pushes downwardly on the central flexible portion 508 of the top wall 507 of the steam generator 500 to urge to membrane breaking membrane 550 against the upper membrane 542 causing said upper membrane to rupture.

At the same time, the downwards movement of the membrane breaking member 550 causes the same to push downwardly on the membrane breaking device 545 in the intermediate section 519, thereby causing that device 545 to push downwardly and rupture the lower membrane 540 between the lower and intermediate sections 518, 519.

Upon rupturing the lower membrane 540, the water or other aqueous substance stored within the intermediate section 519 flows downwards under gravity into the lower section 518 where it contacts said first substance. The first substance reacts exothermically with the water which causes the water to evaporate as steam Steam passes upwardly through the ruptured lower membrane 540 into the intermediate section 519, from where it passes out of the said intermediate section 519 into the upper section 521 via the ruptured upper membrane 542.

The steam then flows from the upper section 521 into the flue portion 554 and is discharged from the steam generator 500 via the steam conduits 561. Said steam pipes 560 may be inserted into any item that it is desired to warm or heat using the steam produced by the steam generator according to the invention. For example, said steam pipes 560 may be inserted into a sandwich or edible wrap for warming the sandwich or wrap prior to consumption With this in mind it is desirable for at least the steam pipes, and preferably the entire device to be sterilised and hygienically wrapped prior to use.

Advantageously, the flue portion 545 defined by said extension portion 552 of the vessel 504 extends beneath the level of the steam outlet pipes 561 to define a liquid trap 565. Thus, any liquid matter that may be sucked or otherwise drawn back into the pipes 561 from the item to be warmed or heated as the steam generator begins to cool drops down into the liquid trap 565 where it is trapped The flue portion 554 includes a drop or downward gradient 556 between the upper section 521 of the vessel 504 and the steam outlet pipes 560 so as to prevent any liquid matter that may flow back from the item to be heated from returning up the flue portion 554 into the vessel 504 FIGS 17 to 28 depict packaging (and components thereof) according to another embodiment of the present invention. The packaging depicted in FIG . 17 is similar to previous embodiments described above in that it comprises a number of components which are fitted together to define the finished article. Specifically, the packaging 600 comprises an upper (in the orientation depicted in FIG. 17) component 602, and a steam generator 604 fitted to the underside of the upper component 602. The upper component is illustrated in detail in FIGS 22 to 24, and the lower component is illustrated in FIGS 25 to 27. Directional references are made in the following description of this embodiment, and such references are made in relation to the packaging as orientated in FIG. 17, and should not be construed as a limitation of the scope of the protection sought. The packaging depicted in FIGS 17 to 28 can readily be manufactured by an injection moulding process.

As depicted in FIGS. 22 to 24, the upper component includes a bowl-shaped portion 606 for receiving food to be heated, and a lateral extension 608 in which a depression 610 for receiving a utensil - in the specific example illustrated, a fork 612 (see FIG. 18) - is formed. The upper component 602 includes a peripheral lip 614 to which a seal, such as a sealing film or a cap configured to snap-fit over the edge of the lip 614, may be attached.

As with previous embodiments, the food to be heated is sealed within the bowl- shaped portion 606 of the packaging, and the seal must be broken by the user to gain access both to the food and to a recessed actuator 615 - the details of which are later described in detail. Of note is the fact that the packaging is depicted in a sealed configuration in FIG. 18, and as such some details of the packaging are obscured. FIG. 19 depicts the packaging in an unsealed configuration where further details of the packaging are visible. In a highly preferred arrangement the food is sealed within the packaging by means of a sealing film secured to the peπpheral lip 614. The film may be secured only to the lip of the packaging, or in a preferred arrangement the film may be secured both to the hp and to a significant portion of a notional line 616 (FIG 18) in the vicinity of the junction of the bowl-shaped portion 606 and the lateral extension 608 In this latter arrangement, the film may be configured to fracture at or around the notional lateral line 616 so that a user can gam access to the utensil and actuator without also having to remove the sealing film from the bowl shaped portion 606 until the food has been heated and is ready for consumption. By secuπng the film to only a significant portion of the notional line 616, vapour generated on operation of the packaging can safely be vented to atmosphere without having to remove that portion of the film which covers the bowl-shaped portion 606. In a highly preferred arrangement, best depicted in FIG. 19, a portion 618 of the lateral extension 608 surrounding the recessed actuator 614 and the utensil depression 610 is corrugated, and this corrugated portion 618 includes a lateral tab portion 620 which extends beyond the notional line 616 to the junction between the bowl shaped portion 606 and the lateral extension 608. The provision of this tab portion 620 provides that even if the film should inadvertently be secured to the top component of the packaging along the entirety of the notional line 616, the troughs of the corrugated portion provide a passageway for vapour to vent to atmosphere during operation of the device.

In general terms, and in common with previously described embodiments, the upper component and the steam generator together provide a means whereby a first substance which reacts exothermically with water can be brought into contact with water (or an aqueous solution) to initiate an exothermic reaction that boils some of the water to generate steam. The upper component and steam generator fit together to define a conduit between the steam generator and a food located in the bowl-shaped portion of the upper component, and on activation by a user generated steam is conveyed through the bowl- shaped portion to heat the food provided therein.

Referring now to FIGS 25 to 27, the steam generator 604 comprises a generally cuboid reagent storage and reaction chamber 622, and lateral peripherals walls 624 of the chamber include a step 626 that defines upper and lower internal chambers 628,630 which are best shown in FIG. 20. Inner and outer concentric annular walls 632, 634 are provided on a top wall 636 of the chamber 622 around a generally circular steam aperture 638 that is closed, prior to operation of the packaging, by a seal or film 644 (FIG. 20) attached to the peripheral edge of the innermost annular wall 632.

The outermost annular wall 634 includes diametrically opposed cut-outs 640 which, as will later be described, are configured to closely mate with the underside of the utensil depression 610 formed in the upper component 602. The outermost annular wall also includes a third larger cut-out 642, generally in-between the two diametrically opposed cut-outs, which reduces the height of the outer concentric wall roughly to that of the inner concentric wall and functions as means by which generated steam can exit from the steam generator. The steam generator 604 further comprises an upper component supporting region 646 which comprises a generally planar base 648 bounded by an upstanding peripheral wall 650 which extends to either side of a tab extension 652 to the planar base that joins the base to the reagent storage and reaction chamber 622. The reagent storage and reaction chamber 622 includes a pair of walls 654 that extend from either side of the third cut-out 642 and join with the upstanding peripheral wall 650 to form one part of a conduit by means of which generated steam can be directed from the reagent storage and reaction chamber 622 to the planar base 648, and ultimately to the upper component 602.

A plurality of upstanding generally triangular supporting walls 656 are joined to the upstanding wall 650, and each of these supporting walls include a profiled edge 658 that at least roughly matches the profile of the underside of the bowl-shaped portion 606 of the upper component 602 and closely abuts the underside of the bowl-shaped portion 606 to support the bowl-shaped portion when the top component 602 is fitted to the steam generator 604. A further upstanding wall extends upwardly within the channel from the step 626 to define a pocket 660 which functions as a liquid trap 660 for the capture of any fluid that might inadvertently be drawn from the top component back towards the steam generator 604.

In a highly preferred configuration, that will later be described in detail, the upper internal chamber 628 is arranged to store water (or an aqueous solution) and the lower internal chamber 630 is arranged to store a substance that reacts exothermically with the water in the upper internal chamber 628 when a barrier or film 664 (FIG. 20) between the upper and lower chambers is broken and the water in the upper chamber flows under gravity into the lower chamber 630. To facilitate dispersion of the heat generated when the water reacts with the exothermic substance in the lower chamber, the lower chamber peripheral wall may be provided with a series of corrugations 662 which act to increase the surface area of the lower chamber peripheral wall and hence increase the rate at which the heat of reaction can be passed to the surrounding air. This arrangement is particularly advantageous as it reduces the chance of a user of the device inadvertently burning themselves if they should, for example, chose to activate the device whist it is held in their hand or placed in their lap.

Referring again to FIGS. 22 to 24, a particular advantage of this embodiment is that as the actuator 615 is located within, and recessed with respect to, the utensil depression 610, a utensil located within the depression extends over and obstructs access to the actuator. By virtue of this arrangement a moderate crush force applied to the upper component, for example whilst the packaging is in transit, should not be sufficient to move the actuator to cause unwanted activation of the steam generator FIG 24 depicts the underside of the upper component 602 and shows both the underside of the aforementioned depression, and the underside of the actuator 615. The bowl-shaped portion 606 of the upper component 602 includes a raised base portion 666 (best viewed in FIG 20) that defines a cavity 668 thereunder The base portion 666 is perforated, as shown in FIG. 21, to permit steam to enter mto the bowl-shaped portion and flow through food contained therein.

As shown in FIGS 22 and 24 (particularly FIG 24), the underside of the upper component is provided with a pair of coextensive downwardly depending spaced parallel walls 670 that extend around the periphery of the underside of the actuator 615 down one peπpheral wall 671 of the bowl-shaped portion 606 and into the cavity 668 formed under the raised base portion 666 The coextensive spaced parallel walls run round the periphery of the underside of the raised base portion 666, exit from the cavity and run up the penpheral wall 671 of the bowl-shaped portion 606 towards the underside of the actuator 615 As shown in FIG 24, the coextensive parallel walls 670 include a pair of downwardly extending stepped portions 672 that cross the underside of the utensil depression 610 (on either side of the actuator) and which are aligned for mating with the diametrically opposed cut-outs 640 in the outermost annular wall 634

As shown inter aha in FIG 20, the coextensive parallel walls 670 form a socket into which the upstanding peπpheral wall 650, the pair of walls 654 extending from either side of the third cut-out 642, and the portion of the outermost annular wall 634 extending between either end of the third cut-out 642 can be plugged to form a steam-tight seal between the upper component 602 and the steam generator 604 In the preferred arrangement the spacing between the coextensive parallel walls is chosen to enable a friction fit between the parallel walls and the aforementioned walls of the steam generator This arrangement is preferred as it avoids having to provide separate sealing elements (such as a rubber sealing strip located to one side of the space between the coextensive parallel walls) and having to actively seal (for example by welding or other sealing method) the walls together Whilst this arrangement is preferred, it will be appreciated however that an alternative sealing arrangement may be provided if desired As will be appreciated, the provision of a steam-tight seal between the steam generator and upper component and is an important safety feature that avoids the potential for steam to be vented from the packaging between the upper component and the steam generator in use. Such venting, were it to occur, would constitute a serious πsk of scalding to a user of the packaging, particularly if that user were to be holding the packaging or resting it on their lap on activation. As depicted in FIG. 20, the actuator 615 comprises a central button 674 (labelled "press to heat" in FIG. 19) joined to the lateral extension 608 of the upper component 602 by means of a corrugated wall portion 676 which, on the application of pressure to the button 674 in a downward direction , straightens to allow the button to move downwardly with respect to the upper component 602.

As aforementioned, the lateral peripheral walls 624 of the generally cuboid reagent storage and reaction chamber 622 a step 626 that defines upper and lower internal chambers 628,630 which are best shown m FIG. 20. The top wall of the cuboid chamber 622 defines the upper wall of the upper chamber 628 and includes the aforementioned generally circular steam aperture 638. The aperture is surrounded by the inner 628 of the two concentric annular walls and is sealed by a first barrier film 644 connected to the peπpheral edge of the inner annular wall.

The upper chamber includes a lower wall defined by a second barrier film 664 attached to the underside of said step 626 in the peripheral wall, and this second barrier film 664 also functions as the top wall for the lower chamber 630 The lower chamber further compπses a base 680.

A spider 682, as is depicted in more detail in Figs 28a to 28c, is sealed within the upper chamber 628 pπor to use of the packaging by the first and second barriers 644 and 664. Referring now to FIGS 28a to 28c, the spider 682 comprises a plurality of limbs 686 arranged in an "X" shaped configuration about a post 688, and a generally cross-shaped member 690 extending upwardly (in the oπentation depicted in FIG 17) from the post. As best depicted in FIG 28c the post and each of the limbs 686 extending from the post are provided with a downwardly depending projection 692 that functions to pierce the second barrier film 664 on application of pressure in a downward direction to the cross-shaped member 690

As mentioned previously in a preferred configuration a measure of water (or other aqueous solution) is sealed within the upper chamber 628, and a measure of a substance that reacts exothermically with water is sealed in the lower chamber 639 Puncturing the second barrier film allows the water and exothermic substance to mix and react , and it is important in this context that all of the water provided in the upper chamber is enabled to flow from the upper chamber into the lower chamber. The reason for this is that the amounts of water and exothermic substance are carefully chosen to control the thermodynamic characteristics of the reaction. For example, if too little water comes into contact with the exothermic reaction, the temperature of the reaction can rapidly escalate to dangerous proportions.

As it is important to carefully control the amounts of water or aqueous solution and exothermic substance, it is equally important to ensure that substantially all of the water provided is enabled to mix with the exothermic substance, and to this end it is preferred that the second barrier film is pierced in more than one location to avoid inadvertent water retention (as might occur if the packaging was not generally horizontal when actuated) in the upper chamber. In the particular arrangement disclosed the barrier film is pierced in five locations (four of which are close to the corners of the upper chamber), but it will be appreciated that a greater or less number of piercing locations may also be employed. It will also be appreciated that the second barrier film could be profiled such that any water in the upper chamber flows towards a single piercing location, but such an arrangement is less preferred on cost grounds.

In operation of the packaging of this embodiment, a user first peels off at least that portion of the film which covers the utensil 612 and actuator 615. The user can then operate the actuator by removing the utensil and pushing the button 674 whereupon the underside of the button abuts against and ultimately breaks the first barrier film 644. On breakage of the first barrier film the upper chamber is in communication with the above described steam conduit between the steam generator 604 and upper component 602. Continued application of pressure brings the underside of the button 674 into abutment with the cross-shaped member 690 and drives the spider to pierce the second barrier film. On piercing of the second film the water or aqueous solution provided in the upper chamber flows under gravity through the pierced second barrier film and contacts the exothermic substance provided in the second chamber. Contact of the water or aqueous solution with the exothermic substance generates heat which boils some of the water to generate steam. The steam flows up through the first and second pierced films, exits the generally cuboid reagent chamber 622 by means of the aperture and enters the steam conduit by means of the third cut-out in the outer annular wall. The steam then flows through the conduit, upwardly through the pierced floor of the bowl-shaped portion and through the food provided therein. Steam that has passed through the food is exhausted from the packaging by means of the troughs in the corrugated tab portion 620, and after a few minutes has passed the reaction ceases and the food is sufficiently warmed for consumption. The user then removes any remaining film to gain access to the food itself.

As with previous embodiments of the invention it is likely that a certain amount of juices will be liberated on heating of the food and it is important to prevent these juices from being drawn from the bowl-shaped portion into the second chamber where the aqueous component of those juices will revive the exothermic reaction. To avoid such a situation the packaging includes a number of fluid traps. The first of these (660), as aforementioned, is provided in the steam conduit between the steam generator and upper component. A second fluid trap is formed by a trough 694 (see FIG. 20) surrounding the raised perforated base of the bowl-shaped portion. The third fluid trap is provided by the space between the raised base portion of the upper component and the planar base 648 of the steam generator 604. By providing three discrete fluid traps the potential for fluid being drawn back into the second chamber is greatly reduced.

Whilst these three fluid traps should prove adequate in all circumstances, certain food (such as a soup for example) may pose a particular problem, and in this context it may be preferable (as with previous embodiments) to include an appropriate valve in the steam conduit between the upper component and the steam generator. Such a valve could usefully be located at or near the third cut-out in the second annular wall. As an alternative the upper component may include a pressure relief valve (for example in that portion of the lateral extension overlying the steam conduit) which is pushed closed on steam generation by the pressure of the steam, and drawn open in the event of a reduction in pressure in the steam conduit. A simple flap valve would provide such a function.

Whilst various preferred embodiments of the present invention have been described above in detail, it will be apparent to persons of skill in the art that a variety of modifications may be made to the particular embodiments disclosed without departing from the scope of the invention. As a consequence it should be understood and noted that all such modifications and equivalents to features claimed are included within the scope of the invention.

Claims

1 A steam generator for generating steam, said steam generator comprising: a first chamber adapted to contain a first substance that reacts exothermically with a second substance to generate steam; a second chamber adapted to contain said second substance; a steam outlet for discharging steam from the steam generator; a first frangible barrier between one of said first and second chambers and said steam outlet a second frangible barrier between said first and second chambers; a first barrier-breaking device operable for breaking said first barrier, thereby to allow steam to pass to the outlet; a second barrier-breaking device positioned within the one chamber and operable for breaking said second barrier to allow said first and second substances to contact one another to react together; wherein said first and second barrier-breaking devices are arranged such that operation of said first barrier-breaking device causes operation of said second barrier- breaking device.

2 A steam generator as claimed in claim 1, wherein said first barrier serves to seal the one chamber from the steam outlet.

3 A steam generator as claimed in claim 1 or claim 2, wherein said second barrier serves to seal the first and second chambers from each other.

4 A steam generator as claimed in claim 1, claim 2 or claim 3, wherein said steam generator comprises a closed vessel having an internal lumen, said first and second chambers being defined by first and second regions respectively of said lumen.

5 A steam generator as claimed in claim 4, wherein said second barrier extends across the lumen to divide said first and second chambers one from the other.

6 A steam generator as claimed in claim 4 or claim 5, wherein said first barrier extends across the lumen to divide the one chamber from the steam outlet. 7 A steam generator as claimed in claim 4, claim 5 or claim 6, wherein said steam outlet is formed in said vessel.

8 A steam generator as claimed in any of claims 4-7, wherein said vessel is sealed, apart from said steam outlet. 9. A steam generator as claimed in any preceding claim, wherein said first barrier- breaking device comprises an actuator movable to break said first barrier and contact a second barrier breaking device located between said first and second barriers before driving said second barrier breaking device to break said second barrier. 10. A steam generator according to claim 9, wherein said second barrier breaking device is arranged to pierce said barrier at a plurality of spaced locations.

11. A steam generator according to claim 10, wherein said second barrier breaking device includes means for facilitating breaking of said second barrier.

12. A steam generator according to claim 11, wherein said facilitating means comprises a plurality of projections located on the underside of said second barrier breaking means.

13. A steam generator according to any of claims 9 to 12, wherein said second barrier breaking device comprises a plurality of angularly spaced limbs.

14. A steam generator according to claim 13, wherein the limbs of said second barrier breaking device are arranged in a generally "X" shaped configuration. 15 A steam generator as claimed in any of claims 1 to 8, wherein said first barrier- breaking device comprises a first barrier engaging member disposed juxtaposed said first barrier, which first member is movable against the first barrier for breaking the same, and a selectively operable pusher for pushing said first member against said first barrier.

16 A steam generator as claimed in claim 16, wherein said first barrier engaging member is connected to said pusher.

17 A steam generator as claimed in claim 15 or claim 16, wherein said vessel comprises a wall portion juxtaposed said first barrier, said pusher being provided in said wall portion.

18 A steam generator as claimed in claim 17, wherein said wall portion is flexible such that it can be flexed towards said first barrier for pushing the first barrier engaging member against said first barrier.

19 A steam generator as claimed in claim 9 or any of claims 15 to 18, wherein said first barrier comprises a flexible membrane, and said first barrier engaging member is adapted to rupture said membrane. 20 A steam generator as claimed in claim 9 or any of claims 15 to 19, wherein said second barrier-breaking device comprises a second barrier engaging member disposed within said one chamber intermediate said first and second barriers, said second member being movable against the second barrier for breaking the same. 21 A steam generator as claimed in claim 20, wherein said second barrier engaging member is configured to be pushed against the second barrier by said first barrier engaging member when the latter is pushed against the first barrier.

22 A steam generator as claimed in claim 20 or claim 21, wherein said second barrier comprises a flexible membrane, and said second barrier engaging member is adapted to rupture the membrane.

23 A steam generator as claimed in any preceding claim, wherein said vessel is configured to define an upright orientation, said first and second regions being provided in lower and upper regions of the vessel respectively, and said second substance is fluent, such that upon breaking said second barrier, said second fluent substance is allowed to flow under gravity into said first chamber to react with said first substance.

24 A steam generator as claimed in claim 23, wherein said steam outlet is provided above said second region, the first barrier being positioned between the second chamber and the outlet. 25. A steam generator as claimed in any preceding claim, comprising valve means associated with said outlet for preventing back-flow into said generator. 26. A steam generator as claimed in any of claims 1 to 24, comprising a pressure release valve associated with said outlet and arranged to open in the event of a negative pressure being established in said generator. 27 Packaging for food comprising an integrant heating device for heating the food, said packaging comprising: a steam generator adapted to generate and discharge steam, said steam generator having a steam outlet; a receptacle adapted to receive an edible substance to be consumed warm, said receptacle having a steam inlet for admitting steam into the receptacle to contact said edible substance; a steam conveying system defining a path for conveying steam from said steam outlet to said steam inlet wherein said packaging is configured to define an upright orientation, said steam conveying system includes a liquid trap that is disposed beneath said steam inlet and said path comprises a fall from said steam outlet to said steam inlet when in said upright orientation, the arrangement being such that any liquid that enters the steam conveying system from the receptacle is caught in said liquid trap and cannot back-flow up the fall to enter the steam generator.

28 Packaging as claimed in claim 27, wherein said path comprises a portion that subtends an angle of less than 70°, preferably less than 45° with said upright. 29 Packaging as claimed in claim 27 or claim 28, wherein said steam conveying system comprises a one-way valve positioned in said path to prevent back-flow of liquids along said path to said steam generator.

30 Packaging as claimed in as claimed in claim 27, claim 28 or claim29, wherein said liquid conveying system comprises a duct from said steam outlet to said steam inlet. 31 Packaging as claimed in any of Claims 27 to 30, wherein said liquid trap comprises a chamber.

32. Packaging as claimed in claim 31 , wherein said receptacle includes a base and said chamber comprises a cavity partly defined by a portion of said base that is raised with respect to the remainder of said base. 33 Packaging as claimed in claim 32, wherein said raised portion is surrounded by a trough, said trough functioning as an additional trap for liquid.

34. Packaging as claimed in any of claims 27 to 33, comprising a liquid trap in said fall between the steam outlet and the steam inlet, said liquid trap comprising a chamber orientated with an opening to said fall so that liquid entering the steam conveying system from the receptacle is caught in said chamber and prevented from entering the steam generator.

35 Packaging as claimed in claim 31, wherein said duct communicates with an upper end of the chamber in said upright orientation, such that steam can pass freely over any liquid trapped in the liquid trap. 36 Packaging as claimed in any of claims 27-35, wherein said steam inlet comprises a diffuser such as a perforated region of said receptacle.

37 Packaging as claimed any of claims 27-36, wherein said inlet is disposed at or towards the lower end of said receptacle in the upright orientation.

38 Packaging as claimed in any of claims 27-37, wherein said receptacle comprises an exhaust for said steam.

39 Packaging as claimed in claim 38, wherein said receptacle comprises an upper rim, and said exhaust comprises one or more grooves formed in said rim. 40 Packaging as claimed in claim 38, wherein said exhaust comprises a corrugated region of said receptacle.

41 Packaging as claimed in any of claims 27-40, wherein said steam generator is adapted to generate heat by selectively bringing into mutual contact first and second substances that are adapted to react together exothermically to generate steam.

42 Packaging as claimed in claim 41, wherein said steam generator comprises a first chamber adapted to contain said first substance, a second chamber adapted to contain said second substance, a frangible barrier between said first and second chambers and a selectively operable barrier breaking device for breaking said barrier to allow said first and second substances to contact one another.

43 Packaging as claimed in claim 42, wherein said first chamber is disposed beneath said second chamber in said upright orientation and said second substance is fluent, such that upon breaking said barrier, said second substance is allowed to flow under gravity into said first chamber to react with said first substance 44 Packaging as claimed in claim 42 or claim 43, wherein said steam outlet is disposed above said second chamber in said upright orientation, such that steam generated by the reaction of said first and second substances passes upwardly through said second chamber before entering said steam conveying system.

45 Food packaging comprising an integrant heating device for heating the food, said packaging comprising: a container comprising or accommodating a receptacle that is adapted to receive an edible substance to be consumed warm, a selectively operable steam generator adapted to generate and discharge steam and a steam conveying system for conveying steam from the steam generator to the interior of said receptacle for heating said edible substance therein; said container having an opening and a sealing rim that extends around said opening, said sealing rim being adapted to mate with a closure for hermetically sealing said container; said steam generator having an actuator that is only accessible via said opening; said receptacle comprising an exhaust for steam in communication with said opening; the arrangement being such that said closure must be at least partially removed from said sealing rim to access said actuator, thereby venting the exhaust to the atmosphere. 46 Food packaging as claimed in claim 45, wherein said sealing rim is adapted to mate with a film closure for forming an hermetic seal.

47. Food packaging as claimed in claim 45 or 46, wherein said container is configured to define an upright orientation and comprises an upper component arranged to fit upon said steam generator, the upper component including said receptacle and comprising an actuator for activating said steam generator.

48. Food packaging as claimed in claim 47, wherein said upper component includes said receptacle and a lateral extension thereto, said actuator being provided in said lateral extension. 49. Food packaging as claimed in claim 48, wherein said lateral extension includes a corrugated region extending to a boundary between the receptacle and said lateral extension, troughs of said corrugated region functioning as said exhaust. 50. Food packaging as claimed in claim 48 or 49, further comprising a receptacle for a utensil. 51. Food packaging as claimed in claim 50, wherein said utensil receptacle comprises a utensil shaped depression formed in said lateral extension of said upper component.

52. Food packaging as claimed in claim 51, wherein a utensil received in said utensil receptacle obstructs access to said actuator.

53. Food packaging as claimed in claim 52, wherein said actuator is recessed with respect to said utensil receptacle and said utensil receptacle extends to either side of said actuator.

54 Food packaging as claimed in claim 45 or claim 46, wherein said container is configured to define an upright orientation and comprises two adjacent, open-topped wells, one of said wells comprising or accommodating said receptacle, and the other accommodating said steam generator, the actuator of the steam generator being accessible via the open top of the other well; and said sealing rim forms a closed figure that extends round said wells such that when fitted said closure extends over and seals the open tops of both wells.

55 Food packaging as claimed in claim 54, wherein said container further comprises a dividing rim that extends between said wells, said dividing rim being substantially coplanar with the sealing rim and being formed with one or more channels extending between said two wells, thereby serving to vent the receptacle when the closure is removed from said other well. 56 Food packaging as claimed in claim 55, wherein said closure comprises a sealing film that can be sealed to said sealing rim and said dividing rim and, whilst remaining in position round the one well, can be peeled back from said sealing rim round said the other well to expose said actuator and to vent the one well via said one or more channels. 57 Food packaging as claimed in claim 55 or claim 56, wherein said container comprises an assembly, which assembly comprises a first part defining said first and second wells, said sealing rim and said dividing rim, said first part being formed with a slot between said wells, which slot extends below said one or more channels, and a second part comprising a wall portion configured to close the open top of said other well beneath the one or more channels formed in said dividing rim, a diffuser portion configured to extend across the interior of the one well towards its lower end and a connecting portion that extends between said wall portion and said diffuser portion and defines a duct for steam between the other well beneath the wall portion, through said slot to the one well beneath the diffuser portion. 58 Food packaging as claimed in claim 57, wherein said wall portion comprises said actuator for the steam generator.

59 Food packaging as claimed in claim 57 or claim 58, wherein said wall portion is sealed to the open top of the other well.

60 Food packaging as claimed in claim 57, claim 58 or claim 59, wherein said first part is configured to cooperate with said connecting part to form said duct.

61 Food packaging as claimed in any of claims 57-60, wherein said connecting part is clipped or otherwise joined to the first part.

62 Food packaging as claimed in any of claims 57-61, wherein the diffuser portion is spaced from the bottom of the one well to form a liquid trap there between. 63 Food packaging as claimed in any of claims 47 to 53, wherein said upper component includes a socket on the underside thereof, the steam generator including means securely receivable within said socket to thereby provide a substantially steam tight coupling between said upper component and said steam generator.

64. Food packaging as claimed in claim 63, wherein the steam generator includes means for supporting said receptacle.

65. Food packaging comprising an integrant heating device for heating the food, the packaging comprising a utensil receptacle , an actuator operable to activate the integrant heating device, and a closure for hermetically sealing the packaging with a utensil received in said receptacle, wherein the packaging is configured such that prior to removal of said closure and the utensil received within said receptacle, said utensil obstructs access to said actuator and thereby protects against inadvertent operation of integrant heating device. 66. An integrant heating device for heating the food, wherein the heating device includes first and second compartments separated by a barrier that when broken permits a fluid reagent located within the first of said compartments to flow under gravity into the second of said compartments and react with a reagent located therein to generate steam, the heating device comprising a barrier breaking device operable to pierce said barrier at a plurality of locations such that substantially all of said fluid reagent contained within the first compartment flows into said second compartment even if the heating device is operated whilst at an angle to the horizontal.

67 Packaging as claimed in any of claims 27-44 or food packaging as claimed in any of claims 45-66, further comprising an edible substance to be consumed warm disposed within said receptacle.