Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B29/00—Packaging of materials presenting special problems
  • B65B29/08—Packaging of edible materials intended to be cooked in the package
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B25/00—Packaging other articles presenting special problems
  • B65B25/001—Packaging other articles presenting special problems of foodstuffs, combined with their conservation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B31/00—Packaging articles or materials under special atmospheric or gaseous conditions; Adding propellants to aerosol containers
  • B65B31/04—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied
  • B65B31/043—Evacuating, pressurising or gasifying filled containers or wrappers by means of nozzles through which air or other gas, e.g. an inert gas, is withdrawn or supplied the nozzles acting horizontally between an upper and a lower part of the container or wrapper, e.g. between container and lid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B55/00—Preserving, protecting or purifying packages or package contents in association with packaging
  • B65B55/02—Sterilising, e.g. of complete packages
  • B65B55/12—Sterilising contents prior to, or during, packaging
  • B65B55/19—Sterilising contents prior to, or during, packaging by adding materials intended to remove free oxygen or to develop inhibitor gases, e.g. vapour phase inhibitors

Definitions

• the present invention relates to a method of heat treatment of a product, in particular a food product, contained in a packaging such as a container having at least one deformable wall, in which the product contained in the package is heated, leaving the steam produced by the heating escape through an opening of the package.
• a method of this type is already known from French Patent Application No. 2,852,921.
• Heating the product serves to promote its conservation. It can be a simple cooking, complete or partial, or a pasteurization or sterilization. As is known, pasteurization and sterilization are used to destroy certain bacteria by heating, to push back the deadline for consumption of the product.
• the consumable product is in particular a food product, such as vegetables, fruits or other fresh foods, blanched or pre-cooked, or frozen. It can also be cooked dishes, including for example meat or fish, or any food preparation.
• the packaging After heating, the packaging is closed while its content is still hot. During cooling, be it sudden or gradual, the volume of gas contained inside the package decreases which, the wall of the package being deformable, causes deformation thereof. When the package is formed by a flexible bag, this retraction can be a desired effect.
• European Patent No. 1,265,793 recommends that the package be closed only once the temperature of the product it contains has reached a precise value and that the inside of the package is always under pressure so that the packaging is not deformed after cooling.
• the volume of gas at overpressure during the closure finds, after cooling, a volume that correctly fills the normal internal volume of the package.
• This method is of some interest, but it requires on the one hand to monitor very precisely the temperature of the product inside the package, which is extremely difficult on an industrial scale and, on the other hand, of ensure that the opening of the packaging initially has a dimension such that controlled overpressure will be ensured inside the packaging at the time when it is closed.
• the object of the present invention is to propose a different solution to allow a release of steam during heating and to avoid excessive permanent deformation of the deformable wall of the packaging resulting from the heating.
• This goal is achieved by the fact that the product is heated by bringing it to a desired temperature, a temperature holding step is carried out, the vapor is allowed to escape, and a fluid is introduced. in the package at the end of this temperature maintenance step, and the packaging is completely closed.
• the heating comprises a step of holding at temperature or "chambering" to obtain the value cooker (that is to say a value for cooking desired), pasteurizer or sterilizer desired, and during which let the steam escape.
• a gaseous fluid is introduced into the package to cause an increase in its internal volume by a temporary deformation of its deformable wall and / or cause increased pressure.
• the packaging can then be closed and, when the gas contained inside this package has regained its "normal" volume at room temperature, the packaging will have found a shape close to its initial shape, without excessive deformation.
• the package may be a semi-rigid tray closed with a flexible film and it is possible to choose to inject a slightly insufficient volume of gas so that after cooling, the outer surface of the film is slightly concave, thereby testifying that the product has actually undergone a heat treatment, while the walls of the tray retain their original shape.
• the invention makes it possible to avoid or control the deformations of the package.
• the final form is appreciated at room temperature and at "normal" atmospheric pressure.
• the ambient temperature is the normal storage temperature of the products contained in the package, ie, for frozen products, of the order of -18 ° C., for the products stored in a cold room, of the order of 4 0 C and for products stored without cooling, of the order of 20 0 C.
• the gaseous fluid introduced has a temperature at least close to the temperature of the vapor of the package during the temperature maintenance step. This avoids a thermal shock between the contents of the packaging and the gaseous fluid introduced into the latter. In addition, it ensures that the gaseous fluid corresponds, from the point of view of its temperature, the desired cooking, pasteurization or sterilization criteria. The temperature of this fluid can even be used to promote pasteurization or sterilization.
• the gaseous fluid is a neutral gas, such as nitrogen, a gas mixture nitrogen / oxygen dioxide or air, preferably filtered.
• This gaseous fluid is chosen according to the products treated.
• the introduction of the gaseous fluid is managed so that when the package once closed will return to ambient temperature, the wall thereof is substantially undeformed or deformed in a controlled manner. It is possible to proceed empirically, by introducing, under the same conditions of introduction, different volumes of gaseous fluids in different packages, and then determining what is the volume of fluid introduced which leads to the desired final shape, so as to retain this volume as to be introduced industrially.
• the evaluation of the volume of vapor that escapes can be carried out by direct measurement or, indirectly, depending on the time during which the steam escapes, and taking into account the size of the opening of the package.
• the process can then be industrialized.
• the difference measured in volume may for example be of the order of ⁇ 5% to ⁇ 10%.
• FIG. 1 is a vertical sectional view of a container containing a product, before the heat treatment;
• FIGS 2 and 3 are top views of such a tray for two variants of its opening;
• the tray of FIG. 1 comprises a receptacle portion 1 and a cover wall 2, such as a peelable film, disposed across the opening of this receptacle.
• Food products such as, for example, peeled potatoes 3 are arranged in this tray.
• this tray is made of plastic or aluminum, or a complex such as, for example, cardboard / plastic, cardboard / aluminum or aluminum / plastic and has a relatively thin wall, whose thickness is by example between 0.5 and 2 mm.
• the upper wall of this tray is formed by the film 2, which is sealed on the edge of the tray constituted by the edge IA of the receptacle.
• the materials chosen for the receptacle and the film are of all types known for this type of trays, for example based on aluminum or plastic, in particular polypropylene, possibly loaded as recommended by EP Patent Application No. 1313. 651.
• the film constituting the upper wall 2 forms a wall which is easily deformable.
• the wall of the receptacle 1 is relatively thin, in fact all the walls of the tray are deformable, but the film 2 is more deformable.
• this tray is closed incompletely, leaving an opening. In FIG. 2, this opening is formed by an interruption 4A of the seaming cord 4 between two walls of the package, in this case between the flange IA of the receptacle and the film 2.
• the opening 5 is formed by a hole in a wall of the package, in this case in the film 2, while the sealing bead 4 between the film 2 and the rim of the receptacle is continuous.
• the opening through which the vapor can escape during sealing has relatively small dimensions so that the inside of the packaging is put under overpressure during heating, because this overpressure favors heating products heart food.
• the vapor that emerges comes from, on the one hand, the vaporization of the water initially contained in the package, in particular in the products which are arranged inside, and on the other hand the expansion of the gas initially contained in the package.
• these two sources of off-gas are designated by "steam".
• the tray of FIGS. 1 and 2 is disposed in a heating chamber 6.
• This is in particular a microwave oven or tunnel inside which microwaves are emitted by a generator.
• the tray is carried by a support 8.
• the support 8 may be a conveyor whose path passes through the interior of this tunnel which has an inlet and an outlet for the tray which are not shown.
• several trays can be simultaneously in the tunnel, the length of the latter and the advancement of the conveyor can be adjusted so that the parking time of a tray in the enclosure is sufficient to allow the desired heating .
• the tray and its contents are subjected to heating to, on the one hand, allow a rise in temperature of the product contained in the tray and, on the other hand, perform a temperature maintenance step.
• the temperature maintenance step is conducted such that the food product remains at a temperature of about 80 0 C to 100 0 C for a given time, for example of the order of 3 to 5 minutes.
• the product is brought to a temperature of the order of 120 0 C to 130 0 C for the necessary time, for example of the order of 3 to 5 minutes.
• the steps of heating and temperature maintenance can be performed in the same microwave chamber.
• microwave tunnels arranged end to end may be used, the first using a larger power to perform the temperature rise step, while the second only carries out the temperature holding step, with less power.
• heating by microwaves is only one example, knowing that other heating modes can be used, in particular heating by other electromagnetic waves such as high frequency waves, or else steam heating.
• the temperature maintenance step can be carried out as shown in FIG. 4.
• a gaseous fluid is introduced into the package as shown in FIG. 5. This introduction can be carried out in the heating chamber as shown in FIG. note that it can also be performed after the temperature maintenance step at the outlet of the heating chamber.
• this introduction of the fluid F is carried out by an injection cannula 9 which is engaged in the opening 4A.
• This cannula is connected to a gaseous fluid supply system represented symbolically by a square 10. It should be noted that the introduction of the cannula into the opening 4A is easy since, under the effect of the vapor evolution V, this opening is at least ajar, that is to say that the film 2 is kept locally at a distance from the flange IA.
• the film 2 has further deformed, further increasing the interior volume of the package.
• this closure is achieved by closing the bore 5 with a pellet 5 '.
• the gaseous fluid is introduced through the opening through which the steam is allowed to escape during holding at temperature.
• another port may be used.
• the steam can be introduced by a cannula forming a needle which, for the introduction of the gaseous fluid, pierces a wall of the package. The pierce thus formed is then closed, for example by placing a pellet across this piercing; the opening through which the vapor V has escaped is also closed, for example by sealing or by affixing a pellet.
• the gaseous fluid which is introduced into the package at the end of the temperature maintenance stage has a temperature which is between 80% and 130%, preferably between 90% and 110%, of the temperature of the steam during the temperature holding step.
• a gaseous fluid temperature at least close to the temperature of the steam is advantageous.
• a higher temperature is chosen for this gaseous fluid, especially when it is close to 130% of the temperature of the vapor, one can use the gaseous fluid and heated to promote cooking, pasteurization or sterilization.
• Tests carried out under different conditions of introduction of vapor packaging at the end of the temperature maintenance stage make it possible to determine what are the optimal conditions for introducing the gaseous fluid so that, once the package is closed, and after cooling of its contents, the pressure balance between the inside and outside of the package is such that the walls of this package remain substantially undeformed with respect to that shown in Figure 1 or they are only slightly deformed in the desired manner, only the film 2, for example, being slightly concave.
• the conditions for introducing the gaseous fluid are defined by parameters such as: the temperature of the gaseous fluid introduced, its composition, the volume of the introduced fluid or, to indirectly determine this volume, the duration of the introduction step, the flow of fluid at the outlet of the injection system and entering the packaging, ....
• Tests may also be performed for different types of openings of the package, knowing that the size of the opening obviously influences the volume of vapor escaping from the package during the temperature maintenance step.
• This volume of vapor can be indirectly determined by knowing the time during which the evolution of gas takes place, and the dimensions of the opening, knowing that the pressure of this vapor is generally known elsewhere.
• a volume of gaseous fluid corresponding at least approximately to the volume of vapor that escapes from the packaging during heating and temperature maintenance is introduced.
• these volumes of vapor and gaseous fluid can be determined by tests, empirically and by comparison between different tests.
• volume that escapes For example, one can evaluate the volume that escapes and then introduce a corresponding volume. It is also possible to test under the same conditions by introducing different volumes of gaseous fluid and by comparing the initial repacking mass with its content and mass after closure and cooling which, by calculation gives the difference between the volume of vapor that escaped and the volume of gas introduced.
• the volume of gaseous fluid introduced is determined such that this volume is substantially equal to the volume of vapor that escapes from the packaging during heating and temperature maintenance, preferably being less than this volume.
• the volume of gaseous fluid introduced into the package may be less than 5 to 10% of the volume of vapor that escaped from the latter.
• this concavity is then light enough not to constitute a troublesome deformation for the consumer but, as indicated above, it has certain advantages.
• this concavity is light enough for the package to be considered “substantially undeformed" after cooling.
• the volume of gaseous fluid introduced into the packaging and the volume of vapor that escaped from it are compared under conditions allowing this comparison, in particular by computationally reducing these volumes to volumes equivalent to the same temperature, in particular the ambient temperature.
• the gaseous fluid is introduced into the package, causing deformation of the deformable wall, and the package is closed when it is found that this deformation has reached a given level.
• the introduction of the gaseous fluid can cause deformation of the film 2 (see FIG. 5).
• the level of the deformation is in particular reflected by the amplitude thereof. It has been indicated previously that, during heating, this wall also deforms, but to a lesser extent.
• the flow of steam escaping through the opening 4A or 5 is stabilized, so that the deformation of the film 2 also stabilizes. It is possible to choose to measure the level of deformation at which the package is closed in a relative manner, by comparison between the stabilized deformation during temperature maintenance and the deformation obtained just before closing, after introduction of the gaseous fluid.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Packages (AREA)
• Food Preservation Except Freezing, Refrigeration, And Drying (AREA)
• Control And Other Processes For Unpacking Of Materials (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Package Specialized In Special Use (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=35445845

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (1)

Citations (6)

Family Cites Families (7)

• 2005
  • 2005-04-13 FR FR0503688A patent/FR2884493B1/fr not_active Expired - Fee Related
• 2006
  • 2006-04-12 WO PCT/FR2006/050340 patent/WO2006109000A1/fr active Application Filing
  • 2006-04-12 EP EP06743801A patent/EP1874632B1/fr not_active Not-in-force
  • 2006-04-12 AT AT06743801T patent/ATE421460T1/de not_active IP Right Cessation
  • 2006-04-12 US US11/911,482 patent/US20100062126A1/en not_active Abandoned
  • 2006-04-12 DE DE602006004983T patent/DE602006004983D1/de active Active
  • 2006-04-12 CA CA2611432A patent/CA2611432C/en not_active Expired - Fee Related
  • 2006-04-12 ES ES06743801T patent/ES2321556T3/es active Active

Patent Citations (6)

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