Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
  • B65D81/34—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package
  • B65D81/3446—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents for packaging foodstuffs or other articles intended to be cooked or heated within the package specially adapted to be heated by microwaves
  • B65D81/3453—Rigid containers, e.g. trays, bottles, boxes, cups
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
  • A23L5/10—General methods of cooking foods, e.g. by roasting or frying
  • A23L5/15—General methods of cooking foods, e.g. by roasting or frying using wave energy, irradiation, electrical means or magnetic fields, e.g. oven cooking or roasting using radiant dry heat
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
  • A23L5/10—General methods of cooking foods, e.g. by roasting or frying
  • A23L5/17—General methods of cooking foods, e.g. by roasting or frying in a gaseous atmosphere with forced air or gas circulation, in vacuum or under pressure
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L5/00—Preparation or treatment of foods or foodstuffs, in general; Food or foodstuffs obtained thereby; Materials therefor
  • A23L5/30—Physical treatment, e.g. electrical or magnetic means, wave energy or irradiation
  • A23L5/34—Physical treatment, e.g. electrical or magnetic means, wave energy or irradiation using microwaves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
  • B65D77/22—Details
  • B65D77/225—Pressure relief-valves incorporated in a container wall, e.g. valves comprising at least one elastic element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D2205/00—Venting means
  • B65D2205/02—Venting holes

Definitions

• the present invention relates to a system for preparing a food product, a package for food products and a method for packaging food products.
• the one-way valve is a separate component attached to the cover film and which, at a certain combination of parameters in the form of heat and pressure, opens and closes the package respectively.
• the one-way valve is associated with several problems in that it makes the package more expensive and complicated, and further it is also sensitive to variations in processing parameters. A certain amount of packages with a one-way valve suffers from valve failure, which results in that the packaged food product must be discarded. Further, the one-way valve is sensitive for choice of material in, for example, the cover film, whereby heating of the cooked and packaged food product in a later stage is limited to microwave heating.
• An object of the present invention is to provide a system for preparing a food product, a package and a method for simple and inexpensive packaging of food products.
• a further object is to reduce the abovementioned shortcomings with a oneway valve of food product packages.
• the invention therefore relates to a system for preparing a food product comprising a microwave source for heating a food product, and a package for the food product.
• the package comprises a tray and a cover film comprising an opening for venting of gas at overpressure that is produced when cooking a food product contained in the package during supply of microwaves at a power P.
• the opening has an opening area A adapted so that the ratio between the opening area A and the supplied power P is in the range of 0,005 and 0,06 mm 2 /W, preferably between 0,01 and 0,03 mm 2 /W, and more preferably between 0,015 and 0,025 mm 2 /W.
• the opening thus has a sufficiently large opening area A so that it allows a sufficient flow of gas during cooking to avoid that the package breaks due to overpressure. Further, the opening area A is sufficiently small to maintain an overpressure in the package during a time period after the supply of microwave energy has ceased, which time period allows the package to be sealed in a subsequent processing step.
• the opening area A may be adapted such that the time period is greater than 2 seconds, preferably more than 5 seconds, or more than 10 seconds. Thereby the time period is sufficiently long to allow the package to be sealed in a subsequent processing step.
• the opening may be formed with a smooth edge to minimize points of fracture, which could entail that the package breaks due to overpressure during cooking.
• the opening may be circular. Thereby the edge of the opening is smooth essentially without points of fracture.
• a circular opening is also strong since it provides a large opening area for a minimized perimeter of the edge.
• the opening may be formed in the cover film by perforation of the cover film with a sharp and smooth tool, preferably needle-shaped. Thereby material in the cover film is moved radially outward relative to the extension of the tool and strengthens the edge around the opening. No material is removed from the cover film when using this technology.
• Another advantage with this technology is that openings may be formed in the cover film in a later processing step, when the cover film already is sealed to the tray. Since no material is removed from the cover film, there is no risk that material from the cover film is brought into the packaged food product.
• the opening may be formed in the cover film by perforation of the cover film by means of laser cutting, punching or melting. Since these technologies entail a removal of material from the cover film (evaporation when laser cutting, mechanical removal when punching, and removal when melting), openings should be pre-formed in the cover film with these technologies, before it is sealed to the tray. Laser cutting has the advantage of very precisely being able to define the form and shape of the opening.
• the microwave power may be in the range 200-800 W, preferably 300-600 W, more preferably 400-500W.
• the opening area A may be between 3-8 mm 2 .
• the opening may be provided at a central portion of the cover film.
• the plastic film may comprise a ductile material, preferably polyamide. Thereby it is achieved a mechanical stability in the cover film, to withstand the overpressure that occurs during cooking.
• the plastic film may also comprise a barrier material, such as polypropylene and/or polyamide, which works as barrier material for diffusion of oxygen into the food product.
• the plastic film may further comprise a material which is suitable for being attached to the tray by heating or welding. Examples of such materials may be polypropylene or polyethylene, depending on the material used in the tray.
• the package may further comprise an adhesive label intended for sealing the opening and which comprises a barrier material.
• an adhesive label intended for sealing the opening and which comprises a barrier material.
• the number of openings in the cover film may be several, which jointly form the opening area A so that they allow a sufficient flow of gas during cooking to avoid that the package breaks due to overpressure. Thereby it is achieved a further strengthening of the opening, since forces that arise around the edges of the opening during the influence of the overpressure in the package are distributed over a larger edge length for a given opening area.
• Each opening is preferably formed with a smooth edge, such as circular openings.
• a package is achieved, which is cooked during supply of microwave power where the risk of the package breaking during cooking is small, and where the package, when cooking is completed, in an easy way and during a sufficiently long time period may be sealed in a separate subsequent processing step.
• the sealing of the opening may occur during a time period of more than 2 seconds, preferably more than 5 seconds, or more than 10 seconds after the supply of microwave power has ceased and while an overpressure is being maintained in the package during this time window. Thereby the time period is sufficiently long to allow that the package is sealed in a subsequent processing step.
• the sealing of the opening may occur during a time period in the range of 2- 60 seconds, preferably 5-30 seconds, more preferably 10-20 seconds after the supply of microwave energy has ceased and while an overpressure is maintained in the package during this time window.
• the opening may be formed in the cover film by perforation of the cover film with a sharp and smooth tool, preferably needle-shaped, in such a way that the opening gets a smooth edge. Thereby it is achieved an opening with a smooth edge which minimizes breaking points, which could mean that the package breaks due to overpressure during cooking.
• the opening may be formed by perforation of the cover film after a food product is packaged in the tray and the cover film is sealed to the tray. Thereby the packaged and non-cooked food product is kept sealed until the perforation step.
• the opening may be formed in the cover film by perforation of the cover film by means of laser cutting, punching or melting.
• the opening may be formed by perforation of the cover film before the cover film is sealed to the tray.
• perforated cover film may be supplied to the package on a roll, or cover film may be perforated in a separate processing step before sealing of the package.
• Fig. 1 shows a cross section of a package for food products, at a number of steps (a)-(f) of a method for packaging of food products according to one embodiment of the invention.
• Fig. 2 shows one (a) and several (b) openings in the cover film.
• Fig. 3 shows a method according to one embodiment of the invention.
• Fig. 4 shows a diagram of time t to sealing for different opening areas A.
• Fig. 1 shows a cross section of a package for food products, at a number of method steps (a)-(f).
• Fig. 1 a shows a package 101 comprising a tray 103 with a food product 102 to be packaged and cooked.
• the tray is made in a material that withstands microwave heating and that has a low permeability to oxygen, for example polypropylene.
• the package further comprises a cover film 104 of a material that withstands microwave heating.
• the cover film comprises several layers of different materials, such as a polyamide layer which brings mechanical stability and a barrier function, i.e. a low permeability of oxygen, and a layer, such as polypropylene, for heat welding to the tray.
• the cover film comprises an opening 105, which is located centrally on the cover film relative to the tray. According to the embodiment shown in Fig. 1 a, the opening is formed in the cover film before sealing to the tray. If the cover film is provided on a roll, openings may be pre-formed in the cover film on the roll.
• the openings may be formed in the cover film in a perforation step which is performed before the cover film is sealed to the tray.
• the opening area A may be formed by a single opening 205 in the cover film 204 (Fig. 2a), or by several sub-openings 215 in the cover film 204 (Fig. 2b).
• the sub-openings 215 thus jointly and together form the opening area A.
• each opening 215 is formed with a circular and smooth edge, i.e. without clear breaking points.
• each opening is formed by perforation of the cover film with a sharp and smooth tool with an extension, such as a sharp and smooth needle. Thereby material in the cover film is moved radially outward relative to the extension of the tool and strengthens the edge around the opening. No material is removed from the cover film with this technology.
• Another advantage with this technology is that openings may be formed in the cover film in a later processing step, when the cover film is already sealed to the tray. Since no material is removed from the cover film, no material from the cover film risks being brought into the packaged food product.
• the opening 205 or openings 215 are pre-formed in the cover film before it is sealed to the tray, by perforation of the cover film by means of laser cutting, punching or melting with a heated tool. Since all of these technologies entail a removal of material from the cover film (evaporation when laser cutting, mechanical removal when punching, and removal when melting), they are not suited for openings being able to be formed in the cover film at a later processing step, when the cover film is already sealed to the tray. Laser cutting has the advantage of very precisely being able to define the form and shape of the opening.
• the cover film is sealed to the tray at a joint 106 around the edge of the tray. This may be done for example by applying heat or by welding, such as ultrasonic welding. In the tray there is thereby formed a space 107 which contains said food product and a certain amount of gas (air). The gas in the space 107 may be vented through the opening 105 in the cover film.
• the food product in the package is heated by supply of microwaves 108.
• a typical microwave power is 400-500W.
• the whole absorbed microwave power generates water vapor in the space 107 that holds gas.
• the pressure in this space increases, and the gas is vented out through the opening 105.
• the opening has a sufficiently large opening area A and is formed with a smooth edge so that it allows a sufficient flow of gas during cooking to avoid that the package breaks due to overpressure. Thereby it is avoided that the cover film breaks up due to tension in the film, and that the sealing between cover film and tray is maintained.
• the sealing takes place while there is still an overpressure in the package.
• the opening 105 is sealed, Fig. 1 e, with an adhesive label 1 10 in order to seal the space 107 in the package.
• the adhesive label comprises a layer with barrier properties such as polypropylene, for limiting transportation of oxygen from the surroundings into the space 107 and the food product 102 in the package.
• Fig.3 the corresponding method 300 is shown, for packaging of a food product which comprises the steps of supplying 301 a package for food products according to what has been described above, packaging 302 the food product in the tray, sealing 303 the cover film to the tray, supplying 304 microwave power to the package to cook said food product, ceasing 305 with the supply of microwave power, and in a processing step 306 after the cessation of supply of microwave power, while an overpressure is maintained in the package, sealing said at least one opening in order to seal the package.
• Fig. 4 shows a graph of measured time period (seconds) to sealing for a package, for different opening areas A (mm 2 ).
• the package was cooked at a microwave power of 440 W.
• the ratio between the opening area and supplied power is 0,009 mm 2 /W.
• a time period of 24 s is reached before the package should be sealed.
• the ratio between the opening area and supplied power is 0,01 1 mm 2 /W.
• a time period of 19 s is reached before the package should be sealed.
• the ratio between the opening area and supplied power is 0,012 mm 2 /W. At this opening area, a time period of 16 s is reached before the package should be sealed.
• the ratio between the opening area and supplied power is 0,014 mm 2 /W. At this opening area, a time period of 14 s is reached before the package should be sealed.
• the ratio between opening area and supplied effect is 0,005 mm 2 /W, and at an opening area of 10 mm 2 the ratio is 0,023 mm 2 /W.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Food Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Nutrition Science (AREA)
• Chemical & Material Sciences (AREA)
• Polymers & Plastics (AREA)
• Mechanical Engineering (AREA)
• Package Specialized In Special Use (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=52142386

Family Applications (1)

Country Status (3)

Cited By (1)

Families Citing this family (1)

Citations (8)

• 2013
  • 2013-06-28 SE SE1350794A patent/SE1350794A1/sv not_active Application Discontinuation
• 2014
  • 2014-06-27 WO PCT/SE2014/050805 patent/WO2014209218A1/en active Application Filing
  • 2014-06-27 EP EP14818272.8A patent/EP3022128A4/en not_active Withdrawn

Patent Citations (8)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events