EP0678457B1 - Container with a closing device having a flap and a block of hot-melting material - Google Patents

Abstract

The valve (15), set in one wall (12a) of the container, has one chamber (38) in communication with the outside atmosphere and containing a shut-off element (35), and a second chamber (40) which is linked to the first by a passage (31) covered by the shut-off element. The second chamber is connected to the interior of the container through a channel (41) and holds a block (44) of a thermo-fusible material. The valve housing (18) has an annular collar (17) to attach it to the container wall. As the food product inside the container is cooked the steam and vapours are able to escape through the valve. At the same time the block of easily-fusible material (44) becomes molten. At the end of the cooking process it is drawn into the channel (41) and seals it, preventing the ingress of external air. <IMAGE>

Description

The invention relates to a packaging for food products, suitable for receive food to be cooked at least partially in situ; it relates to particularly an improvement of such packaging, in the form of a device automatic closure, allowing to bag the products to be treated without drawing vacuum and whatever their temperature and ensure in situ cooking with evacuation of water vapor and other gaseous products resulting from cooking and finally to ensure the automatic closing and the natural vacuum during the cooling. The invention also covers any food preparation packed in such packaging.

Precooked foods or food preparations are subject to more and more important but the realization of such conditioning poses problems, especially on an industrial scale. A known process consists, after cooking, of placing raw or pretreated food in a bag, create a sufficient vacuum in this bag and close it by heat sealing. The vacuum must be around 98%. Plastic bags are commonly used having a thickness of about 90 microns. The implementation is done in a bell to vacuum including heat sealing means. Such a machine is commonly qualified as "manual" because it requires an operator and the production rate is weak.

On an industrial scale, the process is necessarily different and the difficulties are other. We use a thermoforming machine with two plastic film rolls unrolled one above the other. The film lower passes over a honeycomb tray located in a vacuum enclosure. We dig the lower film in the cell under the combined effect of temperature and a depression maintained at the bottom of the cell. We place raw food or pretreated in the hollowed out part, then the upper film is deposited and heat sealed on the hollowed-out lower film, so as to define a hermetically sealed package container containing a dose of food preparation.

This packaging method is difficult to implement when some hot food products have a liquid or pasty consistency (e.g. sauces) and may be sucked out of the packaging during training, due to the vacuum. In this case the vacuum obtained is not sufficient, and there is residual air.

French Patent Application No. 2,629,060 describes a shutter system automatic fitted to a packaging in which food can be cooked. This device has a simple valve allowing air, steam and gases products during cooking to come off freely during this cooking; he theoretically prevents outside air from entering the packaging when cooling. The device as described is however too rudimentary and does not not achieve sufficient reliability for industrial operation. In particular, the valve may open during the storage period, causing lose the packaging's quality as a sterile container. So a notable proportion of production risks losing the benefit of in situ pasteurization and certain food preparations may be spoiled at the time of opening the package.

Document EP 0547941 describes an automatic closing device comprising a single room communicating with the outside and inside of the packaging and containing a hot-melt product which can seal the communication of the room with the outside during cooking. These measures is unreliable, as all of the hot-melt product can be expelled at outside during cooking.

The invention provides a packaging provided with a closure device automatic improved, able to solve all the problems mentioned above, while allowing reliable operation on an industrial scale.

More specifically, the invention therefore relates to packaging for products food, capable of receiving food to be cooked at least partially in situ, and comprising an automatic closing device comprising a chamber containing a block of heat-fusible material and capable of communicating with inside and outside of the package, characterized in that said device automatic closure, tightly fixed through a wall of said packaging includes a first chamber communicating with the outside and enclosing a valve and a second chamber enclosing said block of material thermo-fuse communicating, on the one hand, with said first chamber by a passage capable of being closed by said valve and, on the other hand, with a channel of small section, the latter extending between said second chamber and the interior of the packaging so as to be closed by the hot-melt material after melting.

In the above definition, the self-closing device which is present in the form of a small rigid plastic insert, can be suitable for any type of packaging known in flexible or semi-rigid plastic, for example bags or trays. Now, filling a food preparation can be carried out at atmospheric pressure and at any temperature, with raw or pretreated food. Cooking or the final cooking phase takes place in the packaging, but the flap remains open and food is not isolated from the cooker during the cooking cycle. Thereby, air, water vapor and gaseous products given off by the elements themselves during cooking can escape freely from the packaging so that foods are cooked exactly as if they were arranged "loose" in the cooker. Upon cooling, the hot-melt material solidifies in the low section.

According to a remarkable characteristic of the invention, the valve does not have unique mission to maintain the vacuum in the packaging during the entire period of storage. Its main role is to retain the block of hot-melt material when it softens or liquefies during cooking. This could be destroyed or at least damaged, or even expelled from their home by being trained first by gases exiting at high speed during cooking and then sucked inside packaging during the cooling period. The valve also has the function prevent air from entering after cooking; this air could cool the material thermo-fuse too fast and prevent it from closing the small section channel.

In other words, the valve keeps the heat-fusible material in said second chamber during cooking and to ensure that it is not not completely vacuumed inside the package during cooling. In because air cannot enter the packaging, the hot-melt material is entrained in the channel of small section by the only depression created in packaging when the water vapor it contains condenses. The hot-melt material solidifies in the small section channel and closes the latter so definitive, which guarantees the isolation of food products treated during a period of time corresponding to the life of the products. This closure Hermetic and vacuum packaging is not called into question afterwards, if the flap detaches from its seat.

It should be noted that this type of packaging is particularly suitable for cooking in a vacuum steamer, of the kind described, for example, in French patent No. 2,674,116 belonging to the applicant. Sachets of products to be cooked, hermetically sealed by thermoforming machines do not generally cannot be used in such a cooker as the bags are would swell from the initial phase of injecting steam into the cooker. Then condensation created later in the cooker to control the temperature by acting on the depression therein would increase the stress on the bags. AT less of being made of a particularly resistant and therefore expensive material, the packaging may burst during cooking. The invention also allows to solve this particular problem. In all cases, the material films plastic used can be thinner (especially thickness less than 90 microns) which allows savings in packaging.

The invention also relates to a conditioned food preparation, precooked in a package, the latter being hermetically sealed after cooking, said packaging comprising an automatic closing device comprising a chamber and hot-melt material, characterized in that said device automatic closure, tightly fixed through a wall of said packaging, includes a first chamber communicating with the outside and containing a valve, a second chamber communicating with said first chamber by a passage capable of being closed by said valve and a channel small section extending between said second chamber and the interior of the package and containing heat-fusible material closing off said channel.

The hot-melt material may consist of a paraffin "doped" with a synthetic product based on polyethylene, known per se.

The invention marks a significant advance in the field of packaging industrial vacuum food. Because the filling of sachets can be done at atmospheric pressure, and at any temperature liquid or pasty products no longer risk being sucked into the when the bag is evacuated. In addition, this vacuuming taking place by condensation of the water vapor remaining in the packaging at the end of cooking, the definitive and reliable sealing of said packaging is carried out after a process of pasteurization of food products, operated under hygienic conditions optimal.

• la figure 1 illustre schématiquement une préparation alimentaire conditionnée, renfermée dans un emballage conforme à l'invention, où elle a été cuite au moins en partie ;
• la figure 2 est une vue en élévation, en coupe et à grande échelle du dispositif de fermeture automatique équipant l'emballage de la figure 1 ; et
• la figure 3 est une vue selon la flèche III de la figure 2.

Sur la figure 1, on a représenté une préparation alimentaire 11 conditionnée pour une consommation différée. Le conditionnement a été opéré dans un emballage constitué ici d'un sac 12 en matière plastique souple lui-même formé de deux feuilles de matière plastique thermo-soudées l'une à l'autre de façon à englober les produits alimentaires. On distingue sur la figure 1, une empreinte de thermo-soudure 13, périphérique, matérialisant le sac. Ce type d'emballage peut aisément être constitué par une machine de conditionnement automatisé dans laquelle les aliments sont déposés entre deux films de matériau thermoplastique, à la pression atmosphérique, avant que les sacs soient individualisés par l'opération de thermo-soudure.The invention will be better understood and other advantageous characteristics thereof will appear more clearly in the light of the description which follows, given solely by way of example and made with reference to the appended drawings in which:

• Figure 1 schematically illustrates a conditioned food preparation, contained in a package according to the invention, where it was cooked at least in part;
• Figure 2 is an elevational view in section and on a large scale of the automatic closing device fitted to the packaging of Figure 1; and
• FIG. 3 is a view according to arrow III in FIG. 2.

In Figure 1, there is shown a food preparation 11 packaged for deferred consumption. The packaging was carried out in a package consisting here of a bag 12 of flexible plastic material itself formed of two sheets of plastic material heat-sealed to each other so as to include food products. There is in Figure 1, a heat seal imprint 13, peripheral, materializing the bag. This type of packaging can easily be constituted by an automated packaging machine in which the food is deposited between two films of thermoplastic material, at atmospheric pressure, before the bags are separated by the heat-sealing operation.

According to an important characteristic of the invention, one of the walls of the bag 12 is provided with an automatic closing device 15 tightly fixed (by example by heat sealing also) through said wall. These measures at least partially cooks the food in the bag 12, that is to say after the conditioning operation leading to the formation of the weld 13.

Figures 2 and 3 show in detail the structure of the automatic closing 15. This takes the general form of an insert rigid plastic mounted through a hole 16 of a wall 12a of the bag 12. It is provided with an annular collar 17 hermetically welded to this wall 12a. The device 15 essentially comprises a body 18, hollow, in which is defined a first cell 19 and a cap 20 assembled so tight to said body, by a weld 21 extending all around the edge 22 of said first cell. The hollow body 18 consists of a cylindrical part extended by a conical part. The flange 17 came from the outside of the cylindrical part. The cap 20 has a second cell 25 having in its bottom wall 26 at least one hole and preferably several 28 small section likely to establish communication between the cell 25 and outside. In the example, four holes 0.4 mm in diameter are provided. A partitioning element 30 through which a central passage 31 is formed is assembled to the cap 20 by a weld 32 extending all around the edge 33 of said second cell 25. A movable valve 35 is retained in the first cell between the hole 28 and the partitioning element 30.

Thus, the automatic closing device 15 comprises a first chamber 38 defined in the cap 20 and housing the valve 35, communicating by the holes 28 with the outside of the packaging and a second chamber 40 communicating with said first chamber via passage 31 capable of being closed by valve 35. This second chamber is defined by the space left available at the bottom of said first cell 19 by the cap 20 engaged partially in it. A small section channel 41 extends between said second chamber and the inside of the packaging. Given the hot-melt material indicated above, such a channel will have a length of about 1 cm and a diameter of about 1mm.

The second chamber 40 contains, before use (i.e. before cooking food in situ) a block of hot-melt material 44 shown in broken lines in Figure 2. This block is simply held captive in the said second chamber, it does not adhere to the internal wall of the cell. By therefore, even at the start of cooking, it does not prevent circulation from the inside of the packaging to the outside. For the same reason, the valve 35, has a diameter smaller than that of the cell 25 so that, when it is not applied against the partition element 30 forming a seat, the valve is not opposed not to the evacuation of gaseous products to the enclosure of the cooker, through holes 28. It should be noted that the bottom wall 26 of the second cell 25 is curved and that a flat insert 48 provided with peripheral notches 49 is interposed in said second cell between said valve 35 and the holes 28. The valve 35 abuts against this insert 48 when it is repelled by the flow of gases evacuated from packaging but these gases can flow bypassing the valve and crossing the notches 49.

The channel 41 is formed in a radial rib 46 extending between a end of the body 18, at the bottom of the cell 19, and the flange 17. It opens into the packaging in the immediate vicinity of this rigid collar, in a place where it does not no risk of being blocked by the product contained in the packaging or by its wall flexible when the interior space is vacuumed. In addition, this radial rib 46, allows to define a channel 41 of desired length without lengthening the height of the automatic closing device.

When the package contains a food preparation that has been cooked in situ, the plug 44 has lost its shape and the fusible material 44a has engaged in the conduit 41 under the effect of the condensation of vapor in the bag, at the cooling. This is the situation illustrated in Figure 2. More specifically, the behavior of the automatic closing device during the implementation of the packaging is as follows.

Consumable products gathered to form a preparation given food are first introduced into the bag 12 and the latter is closed by thermo-welding. For example, in the case of Figure 1, food preparation can be introduced between two strips of flexible plastic material running in continuous and each package is individualized by a peripheral heat seal 13 surrounding food products. Beforehand, closing devices automatic 15 are fixed to one of the bands, at selected locations and regularly spaced, so that each package includes such a device at a predetermined location. All these operations and the equipment which are within the reach of the skilled person.

Then, the food preparations thus conditioned are subjected to a cooking operation. For example and preferably, such packages, which have been filled to atmospheric pressure, are introduced into a cooker at the steam operating under vacuum, of the type indicated above. From the start of the cooking, communication is possible between the inside of the packaging and the outside of it so that gases escape at high speed by pushing the valve 35 against the insert 48, throughout cooking. So we get so naturally pasteurization of food products cooked in packaging. During this time, the plug of heat-fusible material 44 softens but remains inside the device due to the presence of valve 35. Then, during cooling, the vapor remaining in the packaging begins to condense which has the immediate consequence of closing the valve 35 and prevent relatively cold air from entering the packaging. Of this fact, the hot-melt material is not likely to re-solidify too quickly and it is entrained in the channel 41 by the only suction force resulting from the steam condensation in the packaging. No reverse circulation of cold gas does not risk disturbing the solidification of the heat-fusible material in this channel. After cooling, the packaging is definitively hermetically sealed and contains a perfectly pasteurized food preparation.

Claims (8)

1. Packaging for food products, suitable to hold food to be cooked at least partially in situ, and comprising an automatic closing device comprising a chamber containing a block of hot-melting material and able to communicate with the inside and outside of the package, characterized in that the said automatic closing device, fixed in a sealed manner through a wall (12a) of the said packaging, comprises a first chamber (38) communicating with the outside and enclosing a valve (35) and a second chamber (40) enclosing the said block of hot-melting material (44) communicating on the one hand with the said first chamber via a passage (31) that can be obturated by the said valve and, on the other hand with a small diameter channel (41) this latter extending between the said second chamber and the inside of the packaging so that it is obturated by the hot-melting material after melting.
2. Packaging according to claim 1, characterized in that the said automatic closing device (15) is composed of a body (18) equipped with a circular collar (17) and into which have been fitted a first alveolus (19) and the said channel (41), this latter extending between one end of the said alveolus and the outside of the said body and a cap (20) fixed in a sealed manner to the said body on the side of the said first alveolus (19), the said first chamber and the said passage being defined inside the said cap and the said second chamber being defined by the space left free at the bottom of the said first alveolus by the said cap.
3. Packaging according to claim 2, characterized in that the said cap (20) comprises a second alveolus (38) equipped with at least one hole (28) capable of establishing a communication with the outside, and in that one partitioning element (30), through which the said passage (31) has been contrived, is fixed to the said cap on the side of the said second alveolus (25), the said valve being held in the said second alveolus by the said partitioning element.
4. Packaging according to claim 3, characterized in that an insert (48) equipped with peripheral grooves (49) is inserted into the said second alveolus between the said valve and the said hole.
5. Conditioned food preparation, pre-cooked inside a packaging, this latter being hermetically sealed after cooking, the said packaging comprising an automatic closing device comprising a chamber and some hot-melting material, characterized in that the said automatic closing device (15) is fixed in a sealed manner through a wall (12a) of the said packaging, comprises a first chamber (38) communicating with the outside and enclosing a valve (35), a second chamber communicating with the said first chamber via a passage (38) able to be obturated by the said valve and a small diameter channel (41) extending between the said second chamber (40) and the inside of the packaging and containing some hot-melting material (44a) obturating the said channel.
6. Food preparation conditioned according to claim 5, characterized in that the said automatic closing device (15) is composed of a body (18) equipped with a circular collar (17) and into which are fitted a first alveolus (19) and the said channel (41), this latter extending between one extremity of the said alveolus and the exterior of the said body and of a cap (20) fixed in a sealed manner to the said body on the side of the said first alveolus (19), the said first chamber and the said passage being defined inside the said cap and the said second chamber being defined by the space left free at the bottom of the first alveolus by the said cap.
7. Food preparation conditioned according to claim 6, characterized in that the said cap (20) comprises a second alveolus (38) equipped with at least one hole (28) able to establish a communication with the outside, and in that a partitioning element (30) through which the said passage (31) has been contrived, is fixed to the said cap on the side of the second alveolus (25), the said valve being held in the said second alveolus by the said partitioning element.
8. Food preparation conditioned according to claim 7, characterized in that an insert (48) equipped with peripheral grooves (49) is inserted into the said second alveolus between the said valve and the said hole.

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