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
  • B65D81/3415—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 in hot water, e.g. boil pouches

Definitions

• This invention concerns packaging, and more particularly the packaging of foodstuffs which are to be heated and/or cooked in their packaging.
• packaging materials designed to facilitate the heating and/or cooking of the packaged foods.
• foods are packaged in containers in which the foods themselves are intended to be heated, thereby avoiding transferring the foods to another container in which the food is heated before serving.
• One type of packaging for this purpose consists of a flexible bag or pouch in which the food is sealed, the container and the food therein being heated, for example by placing the package in boiling water or heating it in a microwave oven.
• Another type of package for the purpose consists of a rigid or semi-rigid tray in which the food is sealed with a lid. As with the flexible bags or pouches the food in the trays can be heated by placing the trays in boiling water or heating them in a microwave oven.
• Puncturing the packages presents problems when they are heated in boiling water, since although this allows air to escape from the packages as they are heated, the water used to carry out the heating tends to enter the packages, thereby mixing with the food being heated. Even if only a small hole is made in the packages, so that little if any water enters them during heating, considerable amounts of water can enter the packages through these holes for example by removing the source of heat for heating the water when the food is about to be served. This problem is particularly noticeable with rigid or semi-rigid trays, where the reduction in pressure within the packages resulting from the packages cooling cannot be compensated by the packages themselves collapsing.
• a packaged foodstuff which is to be heated and/or cooked in its packaging, the packaging having at least one microperforation through which gas within the packaging can escape when the packaged foodstuff is heated, said perforation being small enough substantially to prevent water from entering the package when the package is heated in water.
• the present invention provides packaged foodstuffs which can be heated by boiling in water without first puncturing them, and a further advantage is that by using the appropriate materials they can alternatively be heated in a microwave oven, again without the necessity for puncturing.
• the number of microperforations for any particular package of packaged foodstuff will usually be selected to allow gas within the package to escape at a rate which avoids undue expansion of the package as it is heated. In addition to the number of microperforations, their size will also affect the rate at which gas can escape through them. Although increasing the size of the microperforations can be used to increase the rate at which the gas escapes as the packages are heated, the microperforations should still, of course, be small enough substantially to prevent the ingress of water into the packages when they are heated in water. Typically, the microperforations will have a mean diameter of at least 30 ⁇ m, but they usually need not be more than about 200 ⁇ m. A preferred range of mean diameters for the microperforations is from 50 to 150 ⁇ m, and advantageously from 75 to 120 ⁇ m.
• the present invention can be used with packages of various types, for example they can be flexible, e.g. in the form of bags or pouches, or more preferably they can be rigid or semi-rigid, e.g. in the form of trays.
• the microperforations can in general be anywhere in the packages, but it is usually convenient that they be in a polymeric film forming at least part of the packages. In the case of bags or pouches the film can form all or only a part of the packages, while in the case of trays it is usually convenient to use a lidding film and to have the microperforations in the lid.
• Rigid and semi-rigid containers are generally preferred as they facilitate carrying of heated foodstuffs when they have been removed from the source of heat.
• packages of the present invention can usually be substantially identical to hitherto proposed packages.
• the packages can be provided with a removable portion which exposes the microperforations when it is desired to heat them and their contents.
• the removable portion can be in the form of a polymeric film or a metal foil sealed over the microperforations.
• rigid or semi-rigid containers are used in accordance with the invention, they are no more suitable for evacuating and packaging under vacuum than hitherto.
• foodstuffs can be packaged in them in accordance with the present invention and given an extended shelf life either by freezing, or by the use of a controlled or modified atmosphere.
• the present invention is particularly preferred for packages of frozen foods, where sterility is not essential for long-term storage of the food, as the containers can be heated from frozen without the removal of a seal from the microperforations and without the necessity to puncture them.
• the microperforations will in general also serve to prevent liquid in the foodstuff from escaping into the heating water. It will, of course, be appreciated that by their nature the microperforations will allow liquids to flow in and/or out of the containers, but in accordance with the invention this flow can be reduced while allowing gas to escape from the packages when they are heated.
• microperforations are generally unimportant to the present invention, provided they are of a suitable size to achieve the desired purpose.
• it is generally convenient to produce the perforations by known methods such as the use of a high voltage spark discharge or by a laser.
• Perforation using needles or wires is generally not preferred as it is difficult to form sufficiently small holes that water cannot pass through them in significant amounts.
• the number of microperforations per unit area of packages of the present invention should be sufficient to allow gas within the packages to escape while not allowing significant amounts of packaged foodstuff to escape therethrough or allowing significant amounts of water to enter them when they are heated in boiling water. Although in some instances a single microperforation may be adequate to achieve this, it is generally preferred to have a plurality of microperforations, for example to prevent accidental blockage, e.g. by packaged foodstuffs.
• a 5-layer polymeric base web was produced by coextruding through a slit die a core layer of an ethylene/vinyl alcohol copolymer (EVAL - Kuraray Company) with a layer of linear medium density polyethylene (DSM4046 - DSM (UK) Ltd) on one side and a layer of a blend (1:1 by weight) of amorphous glycol-modified polyethylene terephthalate (PETG - Kodar) and a polycarbonate (PK1340 - G E Plastics) on the other, tie layers of an ethylene/maleic anhydride block copolymer being coextruded between the core layer and each of the other two layers.
• the core layer was approximately 15 ⁇ m thick
• the polyethylene layer was approximately 100 ⁇ m thick
• the layer of the blend was approximately 200 ⁇ m thick, with each tie layer being approximately 10 ⁇ m thick.
• a lidding film was produced by microperforating a 70 ⁇ m thick coextruded film of nylon and polyethylene by spark discharge to provide the film with an oxygen permeability at 25°C of about 10000cc/m2/day/atmosphere, the mean diameter of the microperforations being 85 ⁇ m.
• a single portion of a ready prepared meal was placed in one of the 5-layer trays, and the lidding film was heat sealed thereto.
• the packaged food was frozen in the sealed tray, and it was then heated from frozen by placing the intact tray with its lid attached into boiling water for a time sufficient to heat the meal to the necessary temperature. Air within the package escaped through the microperforations, with only slight bulging of the lid.
• the heated tray was then removed from the boiling water, and the lid was opened. Since the tray remained semi-rigid when hot, it was relatively easy to carry and open whilst still hot.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Food Science & Technology (AREA)
• Mechanical Engineering (AREA)
• Package Specialized In Special Use (AREA)
• Packages (AREA)
• Formation And Processing Of Food Products (AREA)
• Food Preservation Except Freezing, Refrigeration, And Drying (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10686870

Family Applications (1)

Country Status (3)

Cited By (4)

Families Citing this family (5)

Citations (4)

Family Cites Families (3)

• 1990
  • 1990-12-12 GB GB9026946A patent/GB2251420A/en not_active Withdrawn
• 1991
  • 1991-12-03 EP EP91311228A patent/EP0490558A1/fr not_active Withdrawn
  • 1991-12-11 JP JP3351000A patent/JPH0549462A/ja active Pending

Patent Citations (4)

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