EP2374613A1 - Packaging for ready meals - Google Patents

Abstract

Food package (1) comprises a shell (3) comprising aluminum or an aluminum alloy and coated with a heat resistant, food-grade polymer (5), which can be closed with a covering foil (11) comprising aluminum or an aluminum alloy. The inner-side of the covering foil is coated with a food grade, heat-resistant sealing wax, which is weldable with the polymer coating of the bowl at least along the shell edges (7). An independent claim is also included for producing the food package, preferably for prepared foods, comprising using a shell made of aluminum or an aluminum alloy, degreasing and chromatizing the surface facing the inner-side of the shell made of aluminum, and then applying a polymer layer or varnishing, based on a heat resistant, food-grade polyester.

Description

The present invention relates to a package for ready meals according to the preamble of claim 1 and a method for their preparation.

Ready meals are usually packaged meals that are individually packaged and contain all the items, for example, for a single meal and are easy to prepare. Normally, such pre-packaged ready meals only need to be heated by the consumer. Are known shell-like or multi-layer bags made of aluminum, plastic or polymer-coated cardboard. The packaging material of the packaged meals depends on their manufacturing processes, the product protection requirements, the distribution channels, the shelf life as well as the type of preparation in the household.

So-called takeaway meals usually have an extremely short shelf life, such as one day. Various packaging and processing technologies in addition to the distribution methods are known to increase shelf life. For example, pre-pasteurized meals packaged under modified atmosphere such as nitrogen and distribution via cold chain (4 ° C) lead to shelf life of 6 to 10 days. Such packages, such as so-called MAP (Modified Atmosphere Packaging) usually only use C-PET and aluminum shells, which in normal home baking ovens are heated at 190 ° C for C-PET and 220 ° C for aluminum bowls for 15-20 min. Ready meals are also heated by microwaves. A microbiologically sufficient safety is not achieved in MAP packed ready meals. The MAP process with increased CO ₂ content prevents or reduces the growth of various aerobic bacteria. However, it promotes the growth of gram positive, pathogenic bacteria. So-called "in-pack" pasteurization and cooled distribution leads to an increase in the shelf life of ready-made meals, depending on the packaged good, up to 36 days. For example, the shelf life of fish products is about 24 days, whereas meat products give 30 days and vegetables, such as potatoes, up to 36 days shelf life. The thermal "in-pack" treatment is characterized by the achieved microbiological safety of the food compared to all other methods. Such meals are typically packaged in thermoformed polymer trays and dense transparencies, pasteurized in a counter-pressure atmosphere. Reheat meals in a hot water bath or microwave. Thermoformable plastics such as polypropylene are not suitable for direct heat exposure in the household oven. Trays made with C-PET are usually heated in a domestic oven at 190 ° C. However, C-PET loses shell stability when heated above 200 ° C.

Freezing processes in turn give a shelf life of 4 to 6 months. However, the freezing process is energy intensive and often the taste of Food or the meal influenced, which is compensated by additional salts or fat. Frozen products are often added with preservatives such as butylated hydroxyamide. For reheating frozen meals in a household oven, the packaging is done in aluminum trays.

Another method for packaging food for a shelf life of more than 6 months, called "in-pack sterilization" is used. This allows the distribution of such products at room temperature. The sterilization process requires absolute tightness of the packing seal to prevent recontamination. However, because polymers such as polypropylene or blends with PVC (polyvinylchloride) are used as sealing materials in aluminum packaging trays and multilayer bag laminates to obtain the required seal and allow for thermal sterilization at> 120 ° C for one hour in an autoclave, heat exposure of the used in the reheating process in a conventional household oven, for example, at 240 ° C for 15-20 minutes impossible. For this reason, such packages are not suitable for reheating or gratinating finished meals in home baking ovens.

In the EP 2 145 759 Finally, a laminate for the production of a food container is proposed by deep drawing, based on an aluminum foil and a biaxially oriented polyester film. The bond takes place by means of a laminate adhesive. In practice, however, detachment of the laminate layers when heated to elevated temperatures resulted.

None of the currently marketed flexible or semi-rigid packaging meets the requirements set for the invention.

It is therefore an object of the present invention, as a result of the above, to propose a package for finished products in which the contents can be kept for a longer period of time at room temperature and the preparation can be done in a conventional oven or optionally in a microwave oven.

Another object of the present invention is to propose such packages which are completely PVC-free.

Yet another object is to propose a package which allows for heating (gratinating) to 220 ° C - 240 ° C and maintains its dimensional stability even at temperatures above 240 ° C.

According to the invention, a packaging, in particular suitable for ready meals, according to the wording of claim 1 is proposed.

To maintain the product quality over a long period of time in uncooled distribution, another claim of the present invention is that the packaging material used has a very high gas and water vapor tightness. The high gas tightness The aluminum used allows the vacuuming of the packaging and the exchange of oxygen with inert gases such as N ₂ , CO ₂ , O ₂ and gas mixtures during the packaging process. The gas composition inside the packaging has a major impact on the packaged food which is subject to varying degrees of physical, microbiological and also biochemical changes. The changes occurring during food storage are usually due to deterioration due to oxidation. Nitrogen, for example, is excellently suitable for oxidation-sensitive and water-attracting constituents such as, for example, some vitamins, protein or dyes, fats and oils, such as those currently contained in ready-to-eat meals. To preserve the protective gas atmosphere until consumption, a high barrier packaging material such as aluminum must be used.

It is proposed that a shell-like container is used consisting largely of aluminum such as an aluminum alloy. For example, the use of an aluminum alloy containing silicon and iron is proposed. Of course, this is an example and all aluminum materials used in the food packaging field as well as aluminum alloys are suitable for the production of the food bowl proposed by the invention.

According to the invention, the aluminum shell is provided on the inside with a heat-resistant, Food-grade polyester coating has, such as a coating of PET (polyethylene terephthalate).

In practice, it has been found that in a package in which the aluminum or aluminum alloy was painted, excellent durability and heating in the domestic oven at up to 240 ° C could be achieved. This is in contrast to the polyester film and aluminum laminates proposed in the prior art. The use of painted aluminum to produce food packaging has for the first time made it possible to propose a truly PVC-free package that meets the above requirements.

For the application of the polymer coating, the aluminum shell is preferably first degreased and chromatized, for example by means of known chromic acid-containing 2-component process. Such chromating processes are generally known for the degreasing and subsequent coating or painting of aluminum materials.

Before the actual painting, it is additionally possible if necessary to apply a primer and a so-called adhesion promoter to the degreasing and chromatized aluminum for improved adhesion of the finally applied lacquer layer. The composition for painting consists, for example, of a partially crosslinkable polyester such as an undamaged polyester, a hydroxyl-functional polyester, etc., as well suited for such coating systems of the prior art known. In addition, the coating composition may contain solvents, fillers, pigments such as titanium dioxide, UV-absorbing additives, active antifoam additives, thickeners, etc. Such compositions for painting aluminum are well known in the art. The painting itself can be done for example by means of spraying, brushing, by means of doctor blade, etc.

It is important that the coating adheres perfectly to the aluminum even under pasteurization and sterilization conditions and, on the other hand, does not give any components to the food stored in the dish. When using laminates, as known from the prior art, it has been shown that on the one hand in pasteurization and sterilization conditions and also later, for example when heated in an oven at 240 ° C, delamination may occur, which in the present invention proposed painted systems can not be observed.

For the closure of the cup-like container, a film is also proposed, consisting of an aluminum alloy, in turn, the above-mentioned silicon-iron-aluminum alloy is suitable. But here too, any aluminum materials or aluminum alloys used in the food industry are suitable for making the cover film. On the outside of the film, this is preferably provided by means of a heat-resistant and printable paint, which of course also at Sterilization conditions has to exhibit excellent adhesion to aluminum. Again, it may be useful or necessary to chromatize the aluminum foil prior to coating and optionally to provide by means of an adhesion promoter or primer.

On the, the shell inside facing surface of the aluminum foil, in turn, a food-grade and good heat-resistant polymer layer is provided, which in addition has a good weldability with the polymer inner coating of the aluminum shell along the edge. Possible materials are polypropylene as well as possibly in turn the polyester used for the inner coating, such as, for example, partially cross-linked PET. Essential to the invention is now that this aluminum foil interior coating is PVC-free, as PVC in food packaging, which are heated, for example, in a conventional household oven, is no longer approved in many countries and waste management in particular in the combustion or recycling of aluminum by heat separation causing significant problems due to the release of chloride. In general, caution is observed when using PVC in packaging, which has led to a large number of well-known market participants only using PVC where technical / technological alternatives are not available.

Also, the aluminum foil inside is advantageously initially degreased and chromatized, again a chromsäurehaltiges-2-component method suitable for this purpose is. Before the application of the polymer layer, an adhesion promoter, such as a so-called primer, can likewise be used in order to increase the adhesion of the polymer layer, for example a so-called sealing lacquer.

Since no PVC-like polymers are used for the aluminum cover film, special attention must be paid to the adhesion of the sealing layer. This is the task of the primer layer, which on the one hand imparts adhesion to the aluminum foil and on the other hand with the PET sealing layer. Adhesion promoter and sealing layer are applied according to the invention in the painting process.

It is important that on the one hand the coating layers with each other and that for the coating or painting of that surface of the aluminum foil, which faces the inside of the aluminum shell and the polymer used for the interior painting of the aluminum shell are well welded together to the temperatures usually used in sterilization in the Range of about 120 ° C and the increased pressures and high process humidity withstand. Even if the sterilization normally takes place in an autoclave with a dynamic course of the heating and counter-pressure process, ie with an increased external pressure, nevertheless an increased pressure arises inside the food packaging. This in particular as a result of increased vapor pressure inside the food packaging.

• Sterilisierbarkeit und Pasteurisierbarkeit sämtlicher Materialen und Sicherstellung der Dichtheit der Verpackung,
• Wasserdampfresistenz während dem Pasteurisations- resp. Sterilisationsprozess, sowie auf den Aussenseiten des Behältnisses,
• Druckbeständigkeit des Behältnisses bei 0,5 bis 0,8bar,
• keine Geruchsbildung auch unter Pasteurisierungs-, Sterilisations- und Zubereitungsbedingungen in einem Backofen,
• absolut PVC frei,
• kein Epoxy bzw. Bisphenol A enthaltend,
• zubereitbar in einem Backofen bei 220°C bis 240°C während mindestens 15 Min.,
• Formstabil in der Erhitzung,
• keine Delamination irgendwelcher Beschichtungen,
• sämtliche Materialen entsprechen Lebensmitteltauglichkeit (FDA),
• Gute vollständige Öffnungscharakteristik (Peeling) der Abdeckfolie von der Schale.

The requirements for the packaging proposed according to the invention, in particular for food and ready meals, include:

• Sterilizability and pasteurizability of all materials and ensuring the tightness of the packaging,
• Water vapor resistance during the pasteurization resp. Sterilization process, as well as on the outside of the container,
• Pressure resistance of the container at 0.5 to 0.8 bar,
• no odor even under pasteurization, sterilization and cooking conditions in an oven,
• absolutely PVC free,
• containing no epoxy or bisphenol A,
• Prepared in an oven at 220 ° C to 240 ° C for at least 15 min.,
• Dimensionally stable in the heating,
• no delamination of any coatings,
• all materials comply with food suitability (FDA),
• Good complete opening characteristic (peeling) of the cover film from the shell.

• Distribution bei Raumtemperatur,
• lange Haltbarkeit der Produkte wie beispielsweise mehr als 6 Monate,
• zuverlässige Dichtung der Verpackung während der Sterilisation bei mindestens 120°C während mindestens 1 Stunde.

In compliance with the above-mentioned conditions, the proposed packaging according to the invention meets the requirements initially set such as

• Distribution at room temperature,
• long shelf life of products such as more than 6 months,
• reliable sealing of the packaging during sterilization at least 120 ° C for at least 1 hour.

The invention will now be further explained by way of example and with reference to the accompanying drawings.

In FIG. 1 is shown in perspective packaging of the invention in a half-open state and in FIG. 2 schematically the structure of an inventive package consisting of shell and lid is shown.

The packaging 1 according to the invention has a shell 3, essentially consisting of aluminum or an aluminum alloy such as, for example, an EN AW 8011A aluminum alloy with iron and silicon. On the inside of the aluminum shell 3, a heat-resistant, food-grade polymer coating is provided, for example consisting of a good heat-resistant polyester such as partially cross-linked PET. For the application of this polymer layer, the aluminum or the aluminum alloy is first chromatised and then provided with an adhesion promoter such as a primer. The production of the shell itself is carried out by conventional, known methods, for example by deep drawing, the shell above the top has an edge 7 projecting.

For the closure of the shell, an aluminum foil 11 is also provided, which in turn may consist of aluminum or an aluminum alloy. On the outside, the aluminum foil 11 is preferably provided by means of a printable paint 13, for the characterization of the goods packed in the shell such as a ready-made meal.

On the inside of the film 11, this is provided by means of a polymer coating 15, which in turn is food-grade and heat-resistant. It is essential that this polymer coating 15 along the edge portion 17, congruent with the protruding edge 7 of the shell 3 and the internal polymer coating provided thereon is well weldable. The weldability has to be such that absolute tightness is guaranteed even during or after sterilization of the packaging with the finished meal arranged therein. As possible materials, for example, cross-linked PET come into question. For the application of this coating 15 on the inside of the film 11, this is preferably first chromatized and then provided with an adhesion promoter such as a so-called primer.

It is important, of course, that the design of the lid with that of the shell matches exactly to allow accurate welding along the edge parts 7 and 17.

Of course, it is possible to design the cover so that, for example, with a laterally projecting edge portion or a "flap" a light Removal of the lid is made possible by the shell. The slight removal resp. a slight "peel off" of the lid is also important in the design of the weld along the two edge parts 7 and 17.

FIG. 2 shows schematically the construction of shell material and lid material.

The illustration, according to the attached figures, are only examples for a better explanation of the present invention. Of course, the shell can be chosen differently and also the choice of the lid may be different. Also, the container may be bag-like, it is important that in the manufacture or after packaging of a food such as a ready meal, a good weldability is enabled.

The high-density welding of highly heat-resistant polymers such as PET is difficult on the commercial packaging equipment or only possible by means of expensive upgrade. The prerequisite for the welding of high-temperature resistant polymers is on the one hand the coordination of the crosslinking of the respective polymer layers with one another and, on the other hand, with the welding technology to be used. In order to achieve the necessary cohesive welding of the cover and the shell coating, according to the invention, permanently heated flat-type tools compatible with the sealing edge are used, which in absolute flatness corresponds to a heat supply to the structure which is adapted to the structure of the packaging substrate Cover upper and lower shell sides under constant, high pressure conditions during a very short time window allow.

Claims (14)

Food packaging especially for ready meals comprising a shell (3) consisting largely of aluminum or an aluminum alloy, which is coated with a heat-resistant, food-grade polymer (5), which shell is closable, with a likewise largely made of aluminum or an aluminum alloy cover (11 ) which is coated on the inside with a food-grade, heat-resistant sealing wax (15), which is weldable with the polymer coating of the shell at least along the shell edge (7, 17). Packaging according to claim 1, characterized in that an aluminum alloy is used at least containing iron and silicon. Packaging according to one of claims 1 or 2, characterized in that the polymer coating of the shell is based on a polyester, in particular based on an at least partially crosslinked PET (polyethylene terephthalate). Packaging according to one of claims 1 to 3, characterized in that the cover film facing the inside of the shell has a polymer coating or coating based on polypropylene or a polyester such as in particular partially cross-linked PET. Packaging according to one of claims 1 to 5, characterized in that the weldability of the polymers is such that upon sterilization or pasteurization of the packaging absolute density of the weld is ensured. A process for producing a food package, in particular for ready meals, characterized in that a shell made of aluminum or an aluminum alloy is used, wherein the inside of the shell facing surface of the aluminum is degreased and chromatized, whereupon a polymer layer is applied or painted based on a heat-resistant, food-grade polyester. A method according to claim 6, that for the production of the package, the shell is closed by a foil, based on aluminum or an aluminum alloy, wherein the surface of the film, which faces the shell inside, is first degreased and chromatized, subsequently by means of a bonding agent or primer is provided to finally be provided by means of a polymer coating based on a heat-resistant, food-grade polyester, the coating can be done for example by means of brushing, spraying by means of doctor blade, etc. Method according to one of claims 6 or 7, characterized in that for the interior painting of Shell used polymer or the polyester and the polymer used for the painting of the inside of the cover so well welded together that a good tightness in sterilization or pasteurization of the packaging is ensured. Packaging according to one of claims 1-8, characterized in that it has a high gas-tightness <0.1 cm 3 / m 2/24 h / atm / 20 ° C / 80% RH. Packaging according to one of claims 1-9, characterized in that it contains absolutely no PVC. Packaging according to one of claims 1-10, characterized in that it is easy to open manually. Packaging characterized in that it is exposed to a heat load of up to 240 ° C interchangeable. Packaging characterized in that it remains dimensionally stable during and after the heating process. Packaging characterized in that the coating remains neutral during the heating process.

Images