EP1245504A1

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Info

Publication number: EP1245504A1
Application number: EP01107683A
Authority: EP
Inventors: designation of the inventor has not yet been filed The
Original assignee: Cryovac LLC
Current assignee: Cryovac LLC
Priority date: 2001-03-28
Filing date: 2001-03-28
Publication date: 2002-10-02
Also published as: WO2002080623A9; WO2002080623A1

Abstract

The invention is directed to a microwaveable double bag comprising aninner perforated bag (20) of a thermoplastic flexible material, asubstantially imperforated, moisture-proof outer bag (10) of athermoplastic flexible material and an absorbing pad (30), fastened tothe inner surface of the outer bag. Said double bag is used to packagefood products (40) that require a suitable humidity level for theirproper storage and/or thawing, cooking or re-heating. In use, the padcontained in the double bag is suitably moisturized with the requiredamount of steam-generating liquid, e.g. water, wine, etc., before,during or just after loading the food product into the inner bag, theatmosphere within the package is optionally modified to increase theshelf-life of the food product and the double bag is then closed, withthe inner bag inside the outer one. The package obtained can then bestored and passed into the microwave oven when the steam thawing, and/orcooking and/or re-heating of the packaged product is desired.

Description

The present invention relates to an improved storage and cook-in flexible container foruse in the packaging of food products that require moisturized conditions for their properstorage and/or thawing and/or cooking and/or re-heating.
The invention also relates to a food product stored and cooked or re-heated in said flexiblecontainer and to a method of packaging a food product using said flexible container.

BACKGROUND OF THE INVENTION

It is widely known that for many fresh food products the ideal storage conditions require ahumid environment, with a suitable amount of moisture uniformly distributed in theenvironment where the product is stored, to avoid on the one hand the accelerateddehydration of the food product that occurs in dry conditions and on the other hand thegrowth of mould that may occur in case of wetting or over humidification of the product.

It is also known that steam cooking of fresh food products is a very good cooking methodas it preserves the organoleptic qualities (aroma and taste) of the products and maintainsmost of the vitamins and nutritional factors contained therein.

The advantage of using steam is also recognized in connection with the thawing, re-heatingor cooking of frozen foods where the use of a steam environment greatly enhancesthe taste and aroma of the de-frosted products. This particularly when a single stepthawing/cooking or thawing/reheating is carried out.

EP-A-1,053,944 describes a package for the storage and cook-in or re-heat of a foodproduct, said package comprising a tray with a perforated false bottom upon which it isplaced the food product, a moisturized pad positioned between the bottom and the falsebottom of the tray and a thermoplastic film covering the product and closing the package.The product is thus stored under moisturized but not wet conditions and is then cooked,directly into the package, by placing the package into a microwave oven.

The advantages of this packaging system are remarkable as the products, packaged underthe suitable moisturized conditions are maintained fresh for a long period of time and when they are passed into the microwave oven within the package, they are steam-cooked withoutbeing boiled.

The above system however has several disadvantages as the use of rigid receptacles suchas trays, and particularly double bottom trays, requires a huge amount of space in thepackaging facility merely for storing the packaging materials; the cost of such a package ishigh mainly because of the cost of the double bottom trays that are required; and finally theweight and volume of plastic material to be disposed of by the end consumer after usage isvery high.

There is therefore the need to find a way to avoid all the above problems, maintaininghowever the advantages offered by the particular packaging system.

SUMMARY OF THE INVENTION

The solution offered by the present invention is a microwaveable double bag ofthermoplastic flexible material having at least an inner perforated bag, an outer bag and anabsorbing pad, fastened to the inner surface of the outer bag.

In use, just before loading the product in the inner bag of the double bag package, the padis suitably moisturized with the required amount of water, aromatized water or any othersuitable liquid capable of generating steam, the food product is then loaded into the innerperforated bag, and the double bag is closed, with the inner bag inside the outer one. Thesequence of the above steps can also be slightly altered in that the pad can be moisturizedwhile loading the food product into the inner bag or soon after having loaded it but beforeclosing the double bag.

The package thus obtained can then be stored (if the food product is a frozen productunder frozen conditions), while dehydration of the packaged product is controlled, and canbe passed into the microwave oven when thawing, and/or reheating and/or cooking of thepackaged product is desired.

A first object of the present invention is therefore a microwaveable double bagcomprising an inner perforated bag of thermoplastic flexible material, an outer bag of thermoplastic flexible material and an absorbing pad fastened to the inner surface of theouter bag.

A second object is a food package comprising a food product, and a microwaveabledouble bag with an inner perforated bag of thermoplastic flexible material containing saidfood product and an outer bag of thermoplastic flexible material with a pad moisturized witha steam-generating liquid fastened to its inner surface, said outer bag containing the innerbag with the food product.

A third object is a method of packaging a food product in a flexible container suitable forstorage and microwave treatment of the food product (including in this term any thawingand/or cooking and/or re-heating), said method comprising loading the food product into theinner perforated bag of a microwaveable double bag comprising in addition to the innerperforated bag of thermoplastic flexible material also an outer bag of thermoplastic flexiblematerial with a moisturized pad fastened to its inner surface, optionally modifying theatmosphere within the package to increase the shelf-life of the product to be packaged andclosing the double bag.

As used herein the term "double bag" includes the case where the two bags are separatedand are just inserted one within the other to make a double bag, as well as the case where thetwo bags are permanently fastened one to the other. In this latter case, this can be achievede.g. by attaching one or both the top edges of the inner perforated bag to the inner walls ofthe outer bag or by joining the two bags along a line parallel to one or both the top edges ofthe two bags, either by continuous or discontinuous seams.

As used herein the term "microwaveable" when referred to the package according to thepresent invention means that under the conditions required for thawing, cooking or re-heatingthe packaged product into a microwave oven, the packaging material is substantiallynot deformed (by melting or softening and re-shaping upon cooling) and does not releasemore than 60 ppm of global contaminants to the packaged food in contact therewith.

In the actual practice, packaging materials that withstand a heat treatment at 121 °C for ½hour (conditions that are drastic enough not to be reached normally in microwave cooking)without deforming and without releasing more than 60 ppm of contaminants, are consideredto be "microwaveable" according to most of the food laws.

Examples of thermoplastic materials suitable for the manufacture of the flexible packageof the invention include polyolefins (such as propylene-based polymers or preferably crosslinkedpolyethylene-based polymers), polyesters, nylons and any other thermoplasticmaterial that under the conditions of use will not be altered by the microwaves.

Monolayer or multi-layer films can be employed in the manufacture of the double bagaccording to the present invention. There is no need to use the same type of materials for theinner and the outer bag. If the two bags are fastened together by heat-sealing, the twosurfaces that will be fastened together need of course to be heat-sealable and thethermoplastic materials employed will be suitably selected to provide for such heat-sealability.If it is desired to use a modified atmosphere within the package during storage,the thermoplastic material used for the outer bag needs to have gas barrier properties andmulti-layer films with a core EVOH and/or nylon layer will be preferred.

The thickness of the thermoplastic films used for the inner and the outer bag is notparticularly critical and will be selected mainly on the basis of the size of the bag and of theweight of the product to be packaged. Films up to 60 µm are typically employed even ifthicker films may as well be suitably used. Preferred films will have a thickness comprisedbetween about 10 and about 45 µm, and more preferred films will have a thicknesscomprised between about 14 and about 35 µm.

Any pad currently known and used for absorbing fluids from the packaged food products,can be employed in the double bag of the present invention provided it is suitable formicrowave applications. Pads for use in microwave processes are known in the literature andare now commercially available. As an example pads for microwave applications aredescribed e.g. in US-A-5,552,169.

When the food product to be packaged is a fresh food product, any contact between thepackaged product and the liquid in the pad should be possibly prevented. In such a casetherefore the pad may be covered by a plastic film. This however is only preferable and notnecessary as the contact between the packaged product and the liquid in the pad can beprevented in several other ways.

In the double bag according to the present invention, the inner bag is perforated to allowthe steam generated during the cooking step to reach the product. The inner bag may beuniformly perforated or only partially perforated. "Uniformly perforated" means that theperforations are substantially evenly spaced apart from each other over the entire surfacearea of the inner bag.

Whenever it is important to avoid direct contact of the food product with the liquidcontained in the pad during storage, this can be achieved by perforating only part of the innerbag containing the food product, e.g. only one panel thereof, and the double bag is thenmanufactured in such a way that the imperforated part, e.g. the imperforated panel, of theinner bag will overlay the pad. Alternatively this can be achieved by using a uniformlyperforated inner bag but keeping the food product separated from the wet pad by e.g.enclosing the pad in a thermoplastic film perforated only on the surface that faces the innersurface of the outer bag to which it is fastened, or using an outer bag longer than the innerone by more than half the length of the pad and positioning the pad (that in such a case notnecessarily is covered by a plastic film) on the bottom of the outer bag, etc.

The number and size of the perforations in the inner bag should be sufficient to allow thesteam to reach the product and uniformly cook it. While it would be sufficient to have asingle hole to allow the steam to reach the product in the inner bag, it is generally preferredto have at least 1 perforation per 10 cm², typically at least 3 perforations per 10 cm², morepreferably at least 5 perforations per 10 cm², and even more preferably at least 1 perforationper cm². The average diameter of said perforations is typically from about 100 to about 1,000µm, as this is the average size of the holes that are made in-line, by mechanical punching or electrical burning through, in the manufacture of perforated films. Larger holes or smallerholes (e.g. made by laser perforators) could however be foreseen. The number of holes percm² could then be increased (for smaller holes) or reduced (for the larger ones). Or it can beforeseen an inner bag with a combination of holes of different size.

The outer bag is of essentially imperforated, moisture proof, material.

The outer bag may optionally contain a single or a limited number of holes used as venthole(s) during the cooking or re-heating step. Preferably the outer bag contains only one venthole that is covered by a label (with gas barrier properties if a modified atmosphere packageis envisaged) that is removed just before placing the package in the microwave oven forcooking or re-heating the product.

In another preferred embodiment the outer bag does not contain vent holes but has a weakseal or part of it, which opens up when the overpressure within the package reaches a certainthreshold value. Still alternatively the outer bag is imperforated but is of a size suitable tocontain the steam generated during the cooking step without bursting. More sophisticatedsystems, involving the use of valves, can also be foreseen even if such systems may bringabout an increase in the cost of the package and are therefore not preferred.

The outer bag may be printed with e.g. information relating to the content of the bag andthe conditions of storage, and thawing, cooking or re-heating. If the double bag contains atleast a vent hole and a label covering it, said information can alternatively be printed on thelabel that hides the vent hole.

The films for the inner and outer bags are preferably transparent, as the customer shouldbe allowed to look into the package. It is however possible in line of principle to use coloredfilms or opaque films, in particular for those parts of the bags where the presence of the padwill not allow anyway to see through the packaging material.

The pad is fastened to the inner surface of the outer bag by any suitable means. It can beadhered by a hot melt spot or it may be heat-sealed thereto or it can be secured by one or more strips of thermoplastic film that extend across the pad and are fastened to the outer baginner surface by e.g. heat-sealing, thus keeping the pad in place.

While commercial pads are typically rectangular in shape, pads of any shape could besuitably employed in the manufacture of the double bag of the present invention. While inline of principle they may have the same size as the flattened outer bag, it is preferred inpractice to keep their size up to 2/3 the surface of the flattened outer bag and preferably up to1/2 of said surface. The size and thickness of the pad will be suitably selected also dependingon the amount of liquid that needs to be released by the pad during thawing, cooking or re-heatingand therefore on the amount of liquid that needs to be absorbed by the pad at thepackaging step.

The film used for the inner perforated bag is preferably a solid-state oriented and heat-shrinkablefilm. This is achieved by obtaining first a thick sheet (so-called primary tape) byconventional extrusion, co-extrusion, or extrusion-coating techniques; quickly cooling saidtape to slow down crystallization of the resins; re-heating said tape to a temperature that ishigher than the Tg of all the resins making up the tape and lower than the meltingtemperature of at least one of said resins (the so-called orientation temperature); andstretching the heated tape in either one or both longitudinal and transverse directions, toobtain an oriented film that tends to shrink back to the unoriented state when heated to atemperature close to the orientation temperature. Using an oriented heat-shrinkable film, theheat generated during cooking will thus shrink the film of the inner bag. This may be usefulto keep the packaged product in place and maintain its original shape also during the cookingstep. It is also possible, using a heat-shrinkable film for the inner bag, to shrink it just afterthe packaging step. This will allow keeping the packaged product in place also duringstorage.

The use of a heat-shrinkable film for the inner bag however is only preferred but notnecessary and any type of packaging film, whether oriented or non-oriented, shrinkable ornon-shrinkable, can be employed for the inner bag.

In line of principle the outer bag should not shrink under the conditions of cooking, as therapid increase in pressure within the package by the steam generation would be furtherincreased if the volume of the outer bag decreases by a shrinking effect.

Therefore the outer bag is preferably made of a non-oriented thermoplastic film or of anoriented and heat-set thermoplastic film or of an oriented thermoplastic film that hashowever only a minimum shrink at the temperature reached in the cooking step.

The two bags when fastened one to the other in a stable manner can be attachedcontinuously and uniformly along a line that can be a line parallel to the bag mouth of bothbags or that may be a line parallel to the mouth of the outer bag and corresponding to themouth of the inner bag. Alternatively these two bags can be attached also in a discontinuousor intermittent manner along said line. Any means suitable to attach the two bags togetherand that can withstand a microwave treatment can be employed, such as any type of sealing,e.g. hot wire or heated bar sealing, ultrasounds sealing, RF sealing (if the resins used for thebags are RF sealable), and the like, the use of hot melt or pressure sensitive adhesives thatcan withstand a microwave treatment, etc.

The two bags can be made separately, one outer bag with the pad fastened to its innersurface, and an inner perforated bag. In such a case preferably, but not necessarily, at leastone of the dimensions of the inner bag is smaller than the corresponding dimension of theouter bag. These two separated bags are then combined by introducing the inner bag into theouter one. This can be done either before or after the pad is moisturized and either before orafter the product to be packaged is loaded into the perforated inner bag. The last step in thepackaging process is that the mouth of the double bag is closed. The mouths of the two bagsmay be closed either separately or, preferably, they are closed altogether by any suitablemeans, typically by flattening them and heat sealing with a sealing bar, or by gather sealingor by clipping with a microwaveable clip. It is also possible to use reusable closure means,with mateable male and female closure means.

Alternatively the double bag of the present invention can be made starting from twocontinuous flat webs, one of the perforated film for the inner bag and the other one of thesubstantially imperforated film for the outer bag with attached, at a certain distancedetermined by the width of the end double bag, an absorbing pad. The two flat webs aresuperimposed with the pad in-between, they are joined at least along one longitudinal edgeor along a line parallel to one longitudinal edge, by a continuous or discontinuous seam,folded longitudinally and converted into double bags by transversely seal cutting the foldedwebs. Still alternatively the double bag of the present invention can be manufactured startingfrom two center-folded films, an inner perforated film for the inner bag and an outersubstantially imperforated film, bearing the pad attached to its inner surface, for the outerbag. The two films can then be fastened together along both longitudinal edges or along linesparallel and close to both longitudinal edges and converted into bags by a series of transverseseal cuts. With this process it is possible to fasten the pad in the fold on the bottom of thefilm used for the outer bag and employ for the inner bag a center-folded film with a widthsmaller than that of the film for the outer bag so that in the end double bag the inner one willbe shorter than the outer one and any contact between the product to be loaded in the innerbag and the liquid in the pad positioned in the bottom of the outer bag will be prevented.

According to a preferred embodiment of the present invention in all these alternativemethods at least one discontinuity in the fastening of the two webs or bags is present in orderto leave a passage for the liquid that should moisturize the pad before use. If such adiscontinuity is not present, the perforations in the inner bag are preferably large enough toallow the smooth flow of the moisturizing liquid through them before loading the product.

The size of the double bag according to the present invention is not critical as the sameprinciple can apply to small consumer units, such as packages for e.g. 100 to 500 g of foodproduct or even less, to medium size consumer units, such as packages for e.g. 500 to 2,000g of food product, to so-called bulk consumer units, the type of packages that are suitable for the catering/food service industry, such as packages for e.g. 2,000 to 5,000 g of food productor even more.

In a preferred embodiment the double bag has an elongated handle that outwardly extendsfrom the package and is mainly useful to remove the package from the oven at the end of thecooking step. By using the handle the end user will be able to remove the package from theoven without subjecting his or her hands to the high temperature of the package and of thesteam that is given off by the package. Said handle may be attached to the inside or theoutside of anyone of the two bags, it may be of any suitable material and have any shape, asa length of film sufficiently resistant not to break with the weight of the packaged productand sufficiently long to allow prehension by the user hand at a suitable distance from thebody of the package, would fit. Preferably however said handle is attached to the outer-surfaceof the outer bag.

Alternatively a cardboard label may be stuck to the outermost surface of the double bagand be used to grasp the bag with the fingers at the end of the cooking step, the cardboardacting as an insulating material.

The microwaveable double bag of the present invention can be employed for the storageand thawing, cooking or re-heating of a variety of products such as fresh food products, e.g.vegetables, fruits, fish, and the like, a variety of cooked food products such as for instanceprocessed meat, e.g. sausages, and a variety of frozen foods, including ready meals or frozenraw products. The amount of steam-generating liquid to be absorbed by the pad in thepackaging process and the type of liquid to be used can be easily optimized by the personskilled in the art in view of the specific type and weight of product to be packaged.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-section view of a first embodiment of the double bag according to thepresent invention where the inner and the outer bags are separated.

Fig. 2 is a perspective front view of a double bag of the first embodiment where the innerand the outer bags are separated and 2a is a front view of the same bag that has been closed.

Fig. 3 is a cross-section view of a second embodiment of the double bag according to thepresent invention where the inner and the outer bag are fastened together.

Fig. 4 is a perspective front view of a double bag of the second embodiment where theinner and the outer bag are fastened together as illustrated in Fig. 3.

Fig. 5 is a cross-section view of a third embodiment of the double bag according to thepresent invention where the inner and the outer bag are fastened together in a way differentfrom the second embodiment.

Fig. 6 is a perspective front view of a double bag according to the third embodimentwhere the inner and the outer bag are fastened together as illustrated in Fig. 5.

Fig. 7 is a perspective front view of a double bag where the inner is eccentrically arrangedwith respect to the outer bag and the two bags are fastened together only on one side.

Fig. 8 is a schematic view of a preferred process of making the double bag of the presentinvention.

Fig. 9 is a schematic view of another process of making the double bag of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Fig. 1 shows afirst embodiment 1 of the double bag system according to the presentinvention where the inner bag and the outer bag are not fastened together at the time theproduct to be packaged 40 is loaded therein. Theouter bag 10 has afront panel 11 with atopedge 13 and arear panel 12 with atop edge 14 that are united at the bottom either by a foldin the film or by aseam 15. Theinner bag 20 has afront panel 21 with atop edge 23 and arear panel 22 with atop edge 24 that are united at the bottom either by a fold in the film orby aseam 25. 30 is a pad fastened to the inner surface of theouter bag 20. Before loading theproduct 40 in theinner bag 20 or after loading the product but before closing the double bag,thepad 30 is moisturized by pouring any suitable steam-generating liquid (water, wine,aromatized water, etc.) therein. Alternatively thepad 30 may be moisturized first and thenfastened to the inner surface of theouter bag 10.

Fig. 2 shows the same embodiment in a perspective front view where the same numeralsas in Fig. 1 are used to identify the same parts. The outerbag front panel 11 and therearpanel 13 are united at side edges 16 and 17 either by a fold in the film or typically by a seam.The innerbag front panel 21 andrear panel 23 are united at side edges 26 and 27 to create abag. Theinner bag 20 bears perforations 28. 18 indicates the optional vent hole in the outerbag and 19 is the removable label that close the vent hole until the package is put into amicrowave oven. 30 is the pad that is drawn in dotted lines to indicate that it is attached tothe inner surface of the outer bag.

Fig. 2a refers to the same embodiment wherein however once the product has been loadedand the pad moisturized, the mouth of the double bag is closed by welding altogether thefour film webs, i.e. the front panel of theouter bag 11, the front panel of theinner bag 21, therear panel of theinner bag 22, and the rear panel of theouter bag 12, by heat-sealing.Alternatively, but not shown in the Figures, the mouth of both bags can be gathered andeither sealed or clipped using a microwaveable clip.

Another embodiment of the double bag according to the present invention is shown inFigs. 3 and 4. Fig. 3 is a cross-section view and Fig. 4 is a perspective front view of adouble-bag 2 where the

edges

23 and 24 of theinner bag 20 are fastened to the inner walls ofthe outer bag. More particularly in these Figures theedge 23 of the inner bag is fastened tothe inner surface of thefront panel 11 of theouter bag 10, along a linea, continuous, and theedge 24 of the inner bag is fastened to the inner surface of therear panel 12 of theouter bag10 along a lineb, discontinuous. 30 is the pad, 18 the optional vent hole, 19 is the labelcovering the vent hole, and 28 are the perforations in the inner bag.

An advantage of this embodiment resides in the possibility of closing the double bag byheat-sealing together only the two

panels

11 and 12 of theouter bag 10, e.g. by heat-sealingthe flattened bag with a sealing bar, along a line positioned between the

edges

13 and 14 oftheouter bag 10 and the welding linesa andb.

Still another embodiment of a double bag according to the present invention is shown inFigs. 5 and 6, a cross-section view and a perspective front view respectively of athirdembodiment 3 of the double bag of the invention, where the inner and the outer bags arefastened together by a continuousa or a discontinuousb seam, along a line parallel to theedges of both bags and close thereto.

Fig. 7 shows another embodiment where the inner bag is eccentrically inserted into theouter bag and the two bags are fastened together only in few points with a discontinuousseam. This may be achieved by spots of a microwaveable hot melt adhesive or by heat-sealing.

A process for making industrially the double bag according to the present invention wherethe two bags are fastened is shown in Fig. 8. The process there schematically described comprises the following steps

i. unwinding a continuous flat web of the thermoplastic film used for theouter bag 10,

ii. fastening thepads 30 to said flat web at a distance suitably selected in view of thewidth of the end double bag,

iii. aligning and overlaying a continuous flat web of the perforated film used for theinner bag 20 with and onto the first thermoplastic web used for theouter bag 10,

iv. attaching the two webs along two linesa andb parallel to the overlaying edges of thefilm webs or corresponding to said overlaying edges,

v. folding the double web along a longitudinal folding line c, with theweb 10 as theouter web;

vi. converting the folded web into double bags, each one containing at least onepad 30,by transversely seal cutting it.It is also possible to use in said process an overlayingweb 20 that has a width smallerthan that of theunderlying web 10. Said overlayingweb 20 can then be centered on theweb10, provided it is wide enough to extend over and cover entirely thepads 30 or it can alignedwith theunderlying web 10 but positioned eccentrically over the pads and the two

longitudinal edges

23 and 24 of saidflat overlaying web 20 are then attached to theunderlying web 10.Fig. 9 illustrates an alternative method of manufacturing a double bag of the presentinvention that involves the following steps :

vii. unwinding a continuous flat web of the thermoplastic film used for theouter bag 10

viii. fastening thepads 30 to said flat web at a distance suitably selected depending on thewidth of the end double bag,

ix. folding longitudinally theweb 10 with the fastenedpads 30 inside and feeding it to apouch making machine,

x. forwarding to the same machine a secondcontinuous film web 20, foldedlongitudinally, with a transverse web width smaller than the transverse web width ofthefirst film web 10, and attaching the two webs together along the parallel edges,with a continuous seama and/or a discontinuous seamb, e.g. by passing themthrough heated rolls and counter- (or compression) rolls,

xi. seal-cutting the folded webs to form double bags each one containing at least onepad30.

Although the present invention has been described with reference to some specificembodiments of the double bag and the food package of the present invention, it is to beunderstood that these embodiments are given merely to illustrate the principles andapplications of the invention but that modifications and variations may be devised which arewithin the spirit and scope of the present invention.

Claims

A microwaveable double bag comprising an inner perforated bag of thermoplasticflexible material, an outer bag of thermoplastic flexible material and an absorbing padfastened to the inner surface of the outer bag.
The microwaveable double bag of claim 1 wherein the inner perforated bag and the outerbag are permanently fastened one to the other.
The microwaveable bag of claim 2 wherein one or both the top edges of the innerperforated bag are attached to the inner walls of the outer bag or the two bags arefastened together along a line parallel to one or both the top edges of the two bags, eitherby continuous or discontinuous seams.
The microwaveable bag of claim 1 wherein the film used for the inner perforated bag is asolid-state oriented and heat-shrinkable film.
The microwaveable bag of claim 1 wherein the film used for the outer bag essentiallydoes not shrink at the cooking or re-heating conditions.
The microwaveable bag of claim 1 wherein the outer bag contains a single or a limitednumber of holes used as vent hole(s) during the cooking or re-heating step, covered by aremovable label.
The microwaveable bag of claim 1 or 6 wherein the outer bag as well as the labelcovering the optional vent hole(s) has gas barrier properties.
A food package comprising a food product, and a microwaveable double bag accordingto any of the preceding claims, with an inner perforated bag containing said food productand an outer bag with a pad moisturized with a steam-generating liquid fastened to itsinner surface, said outer bag containing the inner bag with the food product.
A method of packaging a food product in a flexible container suitable for storage andmicrowave treatment of the food product, said method comprising loading the foodproduct into the inner perforated bag of a microwaveable double bag according to any ofpreceding claims 1 to 7, moisturizing the pad fastened to the inner surface of the outer bag of said double bag with the suitably selected steam-generating liquid, either before,during or after loading the product into the inner bag, and closing the double bag.
The method of packaging of claim 9 wherein a double bag according to claim 7 isemployed and the atmosphere within the package is modified to increase the shelf life ofthe packaged product before hermetically closing the double bag.