EP1530431A1 - Method for extending the shelf life of perishable agricultural products and/or food - Google Patents

Abstract

In order to extend the shelf life of perishable agricultural products and/or food, said agricultural products and/or food items are placed in a packaging container (10), a modified atmosphere is created in the packaging container (10), and the packaging container (10) is closed. The modified atmosphere is created such that it has a higher oxygen concentration than normal ambient air. The invention consequently relates to a method and a packaging which extend the shelf life of delicate agricultural products and/or food.

Description

 Process for extending the shelf life of perishable agricultural products and / or food

Technical field

The invention relates to a method for extending the shelf life of perishable agricultural products and / or food and a packaging for carrying out the method according to the preamble of the independent claims. State of the art

For the purpose of packaging and / or storing perishable agricultural products and / or foods such as fruit, vegetables, cut flowers, cheese and the like, various methods and devices are known in order to extend the inherently low shelf life of such agricultural products or foods. The so-called MAP (modified atmosphere package) technique, developed over the past few years, has proven to be quite successful, according to which the agricultural products or foodstuffs are stored in packaging that contains an atmosphere that is modified compared to the atmosphere of normal ambient air ,

EP-A2-1 106084 (Comi) describes a method for packaging food products according to which the food products are stored in the packaging in an alcohol-containing atmosphere.

The publication WO-A1 -01/89310 (Steffen) deals with a packaging system for storing fresh agricultural products and / or food. The agricultural products or foodstuffs are first filled into a bowl made of polypropylene and provided with an anti-fog coating. Then the air is sucked out of the shell and replaced by a gas mixture consisting of 75% nitrogen and 25% carbon dioxide and then the shell is sealed airtight with a plastic film. A pressure relief valve is used in the plastic film and is made of hard polypropylene and / or polyethylene. The gases generated by the metabolic residual respiration of the agricultural products or food can escape through the pressure relief valve and out of the otherwise tightly sealed package.

In the case of particularly delicate agricultural products and / or foodstuffs, their shelf life still leaves something to be desired, despite the application or use of the methods and packaging previously known for MAP technology. Presentation of the invention

The object of the invention is to provide a method which enables the shelf life of perishable agricultural products and / or foods to be extended in a package, and a package for carrying out the method.

The solution to the problem is defined by the features of the independent claims. According to the invention, a method for extending the shelf life of perishable agricultural products and / or foods such as fruit, vegetables, cut flowers, cheese, meat and the like has the steps of introducing the agricultural products or food into a packaging container to create a modified atmosphere in the packaging container and to close the packaging container. The modified atmosphere is created in such a way that it has an increased oxygen concentration compared to ordinary ambient air.

This means that the method according to the invention comprises a step, at least temporarily (i.e. for a period of several minutes) in the

Packaging container (i.e. in the one enclosed by the packaging container

Interior) to create a modified atmosphere with an increased oxygen concentration. In connection with the present description and the

Claims will be made without any other statements. the oxygen concentration is always the concentration of molecular oxygen (i.e. the

Concentration of O ₂ gas) understood. The high oxygen concentration can with

Help of the process techniques known for the MAP technique can be created, e.g. first the unmodified one, corresponding to the ambient air

Removed atmosphere from the packaging container by evacuation and then one corresponding to the desired modified atmosphere

Gas mixture is passed into the packaging container. In principle, however, other methods of creating the modified atmosphere are also possible. The high oxygen concentration delays the multiplication of both anaerobic and aerobic germs on the packaged goods, ie on the agricultural products or food contained in the packaging container. Furthermore, the high oxygen content in the case of agricultural products which are provided with interfaces as a result of the harvesting process delays browning reactions at the interfaces of the agricultural products contained in the packaging container.

According to a preferred embodiment of the invention, the modified atmosphere is created in such a way that the oxygen concentration in the modified atmosphere is between 40% and 90%, preferably between 60% and 85%, in particular approximately 80%, based on the modified atmosphere as a whole. These concentration ranges have been proven to improve the shelf life of various different vegetables and fruits.

In connection with the present description and the claims, the gas concentrations given in percent are always percentages by volume, unless stated otherwise.

The modified atmosphere is advantageously created in such a way that it additionally has a higher concentration of carbon dioxide (ie CO ₂ gas) compared to normal ambient air, the carbon dioxide concentration preferably being between 2% and 25%, in particular approximately 10%, based on the modified atmosphere overall is. The high carbon dioxide concentration on the one hand delays the metabolic processes, in particular residual breathing, in the packaged goods. On the other hand, the reduced PH value due to the high carbon dioxide concentration delays microbial germ growth. The high carbon dioxide content can be created by introducing external carbon dioxide gas into the packaging container. As an alternative and / or in addition, the high carbon dioxide content can also be built up by the metabolic residual respiration of the packaged goods themselves.

The modified atmosphere can further be created in such a way that it has an increased ozone concentration in comparison with ordinary ambient air. there the ozone concentration (ie the concentration of O ₃ gas) can be between 1% and 17%, preferably between 5% and 16%, in particular between 10% and 15%, based on the oxygen concentration in the modified atmosphere. These ranges of ozone concentration have proven themselves in connection with the method according to the invention for a large number of different agricultural products and / or foods. The ozone sterilizes or disinfects the packaged goods by rendering microorganisms such as fungi, yeasts, bacteria, viruses, etc. harmless. In contrast to the usual disinfection processes by heating the packaged goods or with the help of chlorine gas or propylene oxide, the packaged goods do not undergo any material changes as a result of ozone sterilization. In addition, there are no residues in the packaging container because the ozone is almost completely converted into molecular oxygen within a few hours.

The modified atmosphere is advantageously created in such a way that it further has an increased concentration of an inert gas, preferably a noble gas, compared to ordinary ambient air, the inert gas concentration (based on the modified atmosphere as a whole) preferably between 2% and 10%, in particular approximately Is 8%. Argon, in particular, has proven itself as an inert gas for use in connection with the method according to this variant of the invention.

According to a further preferred embodiment of the method according to the invention, after the packaging container has been closed, it is illuminated with ultraviolet light. On the one hand, numerous microbes are directly rendered harmless by the UV light, which contributes to extending the shelf life of the packaged goods. On the other hand, due to the high oxygen concentration, the ultraviolet light generates ozone in the sealed packaging container. As described further above, this ozone acts as a sterilizing agent for the packaged goods and in this way in turn contributes to extending the shelf life of the packaged goods.

The packaging container can, for example, be illuminated with ultraviolet light, which has an intensity between 0.1 and 2.0 W / m ² , for more than two minutes. The packaging container is preferably illuminated with ultraviolet light in such a way that the energy density (ie the energy per unit area) of the ultraviolet light incident on the packaging container is between 2,000 mW sec cm ^"2 (20 kJ m ^{" 2} ) and 100,000 mW sec cm ^"2 (100 kJ m ^"2 ). The wavelength of the ultraviolet light can be between approximately 160 and approximately 280 nm. The ultraviolet light preferably has a (spectral) maximum intensity at a wavelength of approximately 185 nm. At this wavelength, the ozone production induced by the ultraviolet light is at a maximum. It is also advantageous if the ultraviolet light has an additional (spectral) intensity maximum at a wavelength of approximately 254 nm as an alternative or in addition to an intensity maximum at a wavelength of approximately 185 nm. at a wavelength of 254 nm, the bactericidal effect of the ultraviolet light is optimal. At the intensities and wavelengths mentioned, an ozone concentration is created in the packaging container in such a way that the shelf life of the agricultural products or foodstuffs contained in the packaging container is significantly extended.

According to a further aspect of the invention, the agricultural products or food are washed with ozone-containing water before being introduced into the packaging container. Washing with ozone-containing water on the one hand causes sterilization or disinfection of the agricultural products or foodstuffs by rendering microorganisms such as fungi, yeasts, bacteria, viruses, etc. harmless. On the other hand, washing with ozone-containing water also indirectly introduces ozone into the packaging container when the agricultural products or foodstuffs together with the remaining stocks of the washing water are introduced into the packaging container. It is obvious that this aspect of the invention does not necessarily have to be used in connection with the increase in the oxygen concentration in the packaging container.

The ozone content of the wash water, which is well suited for improving the durability of the agricultural products or food washed off with the wash water, has an ozone content between 2 and 20 mg / l, preferably an ozone content between 4 and 10 mg / l, in particular an ozone content between 6 and 8 mg / l exposed. A packaging container manufactured according to the method according to the invention, together with the perishable agricultural products and / or foods contained therein, is characterized in that the sealed packaging container contains the agricultural products or foods and a modified atmosphere, the modified atmosphere increasing the air compared to ordinary ambient air Has oxygen concentration. This ensures a long shelf life for the agricultural products or food in the packaging.

According to a further aspect of the invention, a packaging has a packaging container which is designed to hold perishable agricultural products and / or food and to create a modified atmosphere in the packing space delimited by it, is essentially airtight and can be sealed with a gas passage device to allow gases to escape from the

Packroom is provided, which are generated by the metabolic residual respiration of the agricultural products or food contained in the packaging container. The gas passage device is a flat, preferably flexible

Foil structure formed, the at least a portion of the wall of the

Packaging container forms. In the present context, one in

Packaging container that can be essentially sealed airtight to understand a packaging container in such a way that it - with the exception of gas exchange by the

Gas passage means - can be closed airtight to a degree customary for MAP technology.

The formation of the gas passage means as a flat film structure enables simple and inexpensive production of the same in the course of the film production process. In contrast to this, the gas passage means of the type previously used for the MAP technology, as described for example in the publication WO 01/89310 (Steffen) in the form of the one-way pressure relief valve made of hard plastic material, were comparatively complicated to manufacture and therefore correspondingly expensive , The packaging for perishable foodstuffs explained also proves to be advantageous regardless of the increase in the oxygen concentration in the packaging body or the washing off of the packaged goods with washing water containing ozone. The packaging body is typically designed to hold agricultural products and / or foods with a net mass between approximately 0.1 and 10 kg.

The gas passage device, which is designed as a flat film structure, can comprise a semi-permeable plastic film which is designed such that it has a gas permeability of 1O00 cm ³ nr ² day- ¹ (1.16 * 10- ° m sec ^'1 ) over its entire area for molecular oxygen. and 10000 cm ³ m ^"2 days ^{" 1} (1.16 * 10 ^"7 m sec ^{" 1} ), preferably a gas permeability between 3'000 cm ³ m ^"2 days ^-1 (3.5 * 10 ^{" 8} m sec ^-1 ) and 6 '400 cm ³ m ^"2 days ^{" 1} (7.4 * 10 ^"8 m sec ^{" 1} ) and for carbon dioxide a gas permeability between 3'000 cm ³ m ^"2 days ^-1 (3.5 * 10 ^{" 8} m sec ^"1 ) and 30,000 cm ³ m ^"2 days ^-1 (3.5 * 10 ^{" 7} m sec ^"1 ), preferably a gas permeability between 120,000 cm ³ m ^{" 2} days ^"1 (1.39 * 10 ^{" 7} m sec ^"1 ) and 16,000 cm ³ m ^"2 days ^{" 1} (1.86 * 10 ^"7 m sec ^{" 1} ). In particular for comparatively small packagings which are intended to hold packaged goods up to a maximum mass of approximately 2 kg, gas passage devices which are only formed from such semi-permeable plastic films are often sufficient to achieve the desired durability.

As an alternative and / or in addition to a semi-permeable plastic film, however, the gas passage device designed as a flat film structure can also consist of at least two interconnected layers (film layers). Compound film comprise with at least one area defining a pocket, in which the two film layers are not connected to one another and a pressure-sensitive sealant is arranged between the two film layers. In the pocket area, perforations are formed in the two film layers in such a way that they are permeable to gas, but are essentially impermeable to the sealant, so that a gas pressure relief valve is formed overall in the pocket area. In the present context, a pressure-sensitive sealant is a sealant that has a comparatively small pressure difference between the spaces separated from it is tight for gas, while it is permeable to gas with a comparatively large pressure difference. For example, the sealant can be designed such that the gas pressure relief valve formed in the pocket area of the film is sealed for pressure differences of less than approximately 10 mbar (10 hPa), while it is permeable for pressure differences of more than approximately 30 mbar (30 hPa). Depending on the type of packaged goods and / or the packaging container, however, other transition pressures between the sealed and the permeable condition of the pressure relief valve are also possible.

The pressure-sensitive sealant can be a gel-like mass, in particular gel-like silicone oil (also referred to as silicone grease or silicone paste). In principle, however, other suitable pressure-sensitive sealants can also be used.

The perforations are preferably formed at mutually offset locations in the two film layers, between which the pressure-sensitive sealant is enclosed. This ensures good tightness of the gas pressure relief valve formed in the pocket area of the film with small pressure differences, because in this case perforation of one layer is never arranged directly above perforation of the other layer. In principle, however, other arrangements of the perforations are also possible.

According to a further advantageous embodiment of the invention, an antibacterial substance is added to the gel-like mass. This ensures that in the event of bacteria penetrating through the pressure relief valve formed in the pocket area of the film, these bacteria are largely rendered harmless.

A further preferred embodiment of the invention is characterized in that an ethylene-binding (ie an ethylene adsorbing and / or absorbing) substance is admixed to the gel-like mass. Such a substance can in particular be titanium dioxide (TiO ₂ ). The ethylene-binding substance keeps this in the packaging unwanted ripening gas, ethylene, away from the packaged goods, thereby further extending the shelf life of the packaged goods.

Furthermore, at least one part of the wall of the packaging container is preferably designed such that in this part the packaging container wall is highly transparent to ultraviolet light. Such packaging is particularly well suited for using the variants of the method according to the invention, which provide for the illumination of the packaging together with the packaged goods by means of ultraviolet light.

The packaging container is advantageously designed in such a way that it is suitable for cooking the agricultural products or foodstuffs contained in the closed packaging container in a microwave oven. Such a packaging container can e.g. comprise an upwardly open shell, which is made of heat-resistant polypropylene, PET-C (polyethylene terephthalate) or another suitable heat-resistant plastic and is sealed airtight by means of a transparent, flexible cover film made of polyester or another suitable plastic, the cover film according to Kind of a so-called peel closure can be torn off the shell in order to open the packaging container and to consume the packaged goods.

A hydrogel mass, which releases water when heated, is preferably also arranged in the microwave-safe packaging container. This ensures that the water is bound in the hydrogel during storage and transport of the packaged goods at normal temperatures and that the packaged goods are kept essentially dry in the closed packaging container. If the still closed packaging container is then heated in the microwave oven, water is released from the hydrogel, which supports the cooking process in the microwave oven in the form of cooking water and / or steam.

According to a further advantageous aspect of the invention, a drying agent is additionally arranged in the packaging container. The drying agent binds any liquid water present in the packaging container, which has been formed, for example, by condensation and / or by the metabolic residual respiration of the packaged goods. Overall, the desiccant ensures dry storage and thus a further extension of the shelf life of the agricultural products or food contained in the packaging container.

Further advantageous embodiments and combinations of features of the invention result from the following detailed description and the entirety of the claims.

Brief description of the drawings

The drawings used to explain the exemplary embodiment show:

1 shows a packaging container of a packaging according to a first preferred embodiment of the invention in a simplified, perspective representation;

FIG. 2 shows the cover film of the packaging container from FIG. 1 in a simplified plan view from above;

3 shows the cover film from FIG. 2 in a simplified, schematic cross-sectional partial view along the line A-A.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways of Carrying Out the Invention

1 shows a packaging container 10 of a packaging according to a preferred embodiment of the invention in a simplified, perspective representation. The packaging container 10 comprises an upwardly open shell 20 which is made of heat-resistant polypropylene. The packaging container 10 further comprises a transparent, flexible cover film 30, by means of which the shell 20 can be closed essentially airtight by placing the cover film 30 on the upper edge the shell 20 is welded. To open the packaging container 10, the cover film 30 can be torn off from the shell 20 in the manner of a so-called peel seal (also referred to as a tear-off seal). In Fig. 1, the cover sheet 30 is shown partially torn away from the shell 20.

The cover film 30 has an essentially two-layer structure and comprises a first film layer 34 made of polyethylene (PE) and a second film layer 32 made of polyester. In the closed state of the packaging container 10, the film layer 34 made of polyethylene is welded onto the upper edge of the shell and forms the inner side of the cover film 30 facing the packing space or the packaged goods (not shown) accommodated in the bowl, while the film layer 32 Polyester forms the outer side of the cover film 30 facing away from the packaged goods.

With the exception of two rectangular areas 40, 50, the two film layers 32, 34 are connected to one another by lamination in the manner customary for films. In the areas in which the two film layers 32, 34 are laminated together, the cover film 30 forms a semipermeable membrane with a gas permeability between 30,000 cm ³ m ^"2 days ^{" 1} (3.5 * 10 ^"8 m sec ^{" 1} ) and 6,400 cm ³ rrf ² days ^"1 (7.4 * 10 ^{" 8} m sec ^'1 ) for molecular oxygen and a gas permeability between 12'0OO cm ³ m ^"2 days ^{" 1} (1.39 * 10 ^"7 m sec ¹ ) and 1600 cm ³ m ^'2 day ^"1 (1.86 * 10 ^{" 7} m sec ^{' 1} ) for carbon dioxide.

In the two rectangular areas 40, 50, the two film layers 32, 34 are not connected to one another, so that a pocket 40, 50 is formed in each of these areas between the two film layers 32, 34. The pockets 40, 50 are each filled with a mass 46, 56 made of gel-like silicone oil (also referred to as silicone grease or silicone paste). Furthermore, perforations 41, 42, 43, 44, 51, 52, 53, 54 in the film layers 32, 34 are formed in the area of the pockets 40, 50 in such a way that they are permeable to gas, but essentially impermeable to the gel-like silicone oil 46, 56 are. In the embodiment of the invention shown in FIGS. 1 to 3, these perforations 41, 42, 43, 44, 51, 52, 53, 54 each consist of two fine slits 43, 44, 53, 54 in the inner film layer 34 and two fine ones Slots 41, 42, 51, 52 in the outer film layer 32 for both pockets 40, 50, wherein the slots 43, 44, 53, 54 in the inner film layer 34 are each offset with respect to the slots 41, 42, 51, 52 in the outer film layer 32, so that never a slot 41, 42, 51, 52 is arranged in the outer film layer 32 directly above a slot 43, 44, 53, 54 in the inner film layer 34.

The gel-like silicone oil 46, 56 in the two pockets 40, 50 is a pressure-sensitive sealant for gas, because with small pressure differences between the inside and the outside of the cover film 30 it is gas-tight, while with large pressure differences it is permeable to gas. Overall, the two pockets 40, 50 filled with silicone oil 46, 56 each form a gas pressure relief valve which is gas-tight for pressure differences of less than approximately 10 mbar (10 hPa). The two gas pressure relief valves formed by the film pockets 40, 50 are permeable to gas for pressure differences of more than approximately 30 mbar (30 hPa). Thus, at pressure differences of more than approximately 30 mbar (30 hPa), even with the packaging container closed, 10 gas can escape from the packing space through the two film pockets 40, 50 to the outside.

The silicone oil 46, 56 in the film pockets 40, 50 is mixed with an antibacterial substance. It is thereby achieved that, in the event of bacteria penetrating through the pressure relief valves formed in the pocket areas 40, 50 of the cover film 30, these bacteria are largely rendered harmless.

The silicone oil 46, 56 in the film pockets 40, 50. further titanium dioxide (TiO ₂ ) added. The titanium dioxide has an ethylene binding effect. It binds any ethylene formed in the packing room from the packaged goods (not shown) and keeps this unwanted ripening gas away from the packaged goods.

The cover film 30 is made transparent overall and thereby enables a visual inspection of the packaged goods through the cover film 30. However, the cover film 30 is also largely transparent or permeable to ultraviolet light. This enables the packaged goods to be illuminated with ultraviolet light through the cover film 30. Furthermore, the cover film 30 is provided on its inner side facing the packaged goods with a fog-reducing coating (also referred to as an anti-fog coating), so that the clear view through the cover film 30 is not impeded by the formation of drops on the cover film 30.

The packaging container 10 shown in FIGS. 1 to 3 is suitable for microwave ovens. In other words, for cooking the food (not shown) received in the packaging container 10, it can be placed together with the closed packaging container 10 in a microwave oven and cooked using microwaves. After cooking, the cover film 30 can be torn off the dish 20, whereupon the food can be consumed directly from the dish 20.

To support the cooking process, a hydrogel mass (not shown) is also accommodated in the closed packaging container 10 in addition to the food (not shown) forming the packaged goods. At normal ambient temperatures, the water contained in the hydrogel mass remains bound in the hydrogel mass. However, as soon as the packaging together with the packaged goods is heated in the microwave oven, the heating releases at least part of the water contained in the hydrogel mass. This water then supports the cooking process in the microwave oven in the form of cooking water and / or steam.

The packaging container 10 shown in FIGS. 1 to 3 is suitable for the storage of perishable agricultural products and / or foods (not shown) in such a way that they remain long-lasting. It is particularly suitable for storing fresh vegetables such as French beans, carrot sticks, apero sticks, asparagus peeled, broccoli and / or cauliflower rosettes, cheese peppers, pepperoni cut into strips, ratatouille, cut mushrooms, fresh peeled salsify, fruit salads and fruit pieces.

For the long-lasting storage of asparagus by means of the packaging container 10 shown in FIGS. 1 to 3, the asparagus (not shown) are first harvested, peeled and washed in ozone-containing drinking water (not shown) for about three minutes, the ozone content of the water being between 6 and 8 mg / l. Washing with ozone-containing drinking water causes the asparagus to be sterilized for the first time. A desired amount of asparagus with a net mass of approximately 500 g is then filled into the open shell 20 of the packaging container 10, a hydrogel mass (not shown) having previously been poured onto the bottom of the shell 20.

Subsequently, in a system (not shown), as is essentially known for MAP technology, the unmodified atmosphere corresponding to the ambient air is first removed from the shell 20 by evacuation, then a gas mixture corresponding to a modified atmosphere is removed by so-called Back-gassing is introduced into the shell 20 and then the shell 20 is sealed essentially airtight by welding the cover film 30 onto the upper edge of the shell 20. The gas mixture introduced into the shell 20 by back-gassing essentially consists of 70% molecular oxygen, 10% carbon dioxide, 12% ozone and 8% argon. The high content of molecular oxygen and ozone in the modified atmosphere effects a second sterilization of the asparagus accommodated in the packaging container 10 (not shown).

Next, the asparagus in the closed packaging container 10 are illuminated with ultraviolet light through the cover film 30 for approximately two minutes, a light source arranged at a distance of approx. 2 cm from the packaging container emitting ultraviolet light which, when it hits the packaging container, has an intensity of approximately 0.4 W / m ² and has an intensity maximum at a wavelength of approximately 185nm. The energy density of the total of ultraviolet light arriving on the packaging container is thus approximately 4,800 mW sec cm ^"2 (48 kJ m ^{" 2} ). The illumination with ultraviolet light brings about a further sterilization of the asparagus accommodated in the packaging container 10. The asparagus treated in this way can be kept in the closed packaging container 10 for about 3 weeks.

The ozone introduced into the packaging container 10 by the back-gassing and / or generated by the ultraviolet light in the packaging container 10 decomposes again within a few hours into molecular oxygen which passes through the cover film 30 diffuses through to the outside and / or is absorbed by the asparagus in the course of their residual metabolic respiration. After about 24 hours, thanks to the cover film 30, which is semipermeable for molecular oxygen, and the pressure relief valves formed by the film pockets 40, 50, through which carbon dioxide and water vapor can escape, which are produced in the course of the metabolic respiration of the asparagus, a breathing equilibrium is established automatically ,

In summary, it can be stated that the invention provides a method and a packaging which enables the shelf life of delicate agricultural products and / or foods to be extended.

LIST OF REFERENCE NUMBERS

Claims

Patent claims 1. A method for extending the shelf life of perishable agricultural products and/or foodstuffs, the method comprising the steps of introducing the agricultural products or foodstuffs into a packaging container (10), creating a modified atmosphere in the packaging container (10) and the To close packaging containers (10), characterized in that the modified atmosphere is created in such a way that it has an increased oxygen concentration compared to normal ambient air. 2. The method according to claim 1, characterized by creating the modified atmosphere such that the oxygen concentration in the modified Atmosphere is between 40% and 90%, preferably between 60% and 85%, in particular approximately 80%. 3. The method according to claim 1 or 2, characterized by creating the modified atmosphere such that it additionally has an increased concentration of carbon dioxide compared to normal ambient air, the carbon dioxide concentration preferably being between 2% and 25%, in particular approximately 10%. 4. The method according to any one of claims 1 to 3, characterized by creating the modified atmosphere such that it further has an increased ozone concentration compared to normal ambient air, wherein the Ozone concentration is between 1% and 17%, preferably between 5% and 16%, in particular between 10% and 15%, based on the oxygen concentration in the modified atmosphere. 5. The method according to any one of claims 1 to 4, characterized by creating the modified atmosphere in such a way that it is further compared to ordinary ambient air has an increased concentration of an inert gas, preferably a noble gas, the inert gas concentration preferably being between 2% and 10%, in particular approximately 8%. 6. The method according to one of claims 1 to 5, characterized in that after the packaging container (10) has been closed, it is illuminated with ultraviolet light in such a way that ozone is generated by the ultraviolet light due to the high oxygen concentration in the closed packaging container (10). 7. The method according to claim 6, characterized in that the packaging container (10) is illuminated with ultraviolet light in such a way that the energy density of the ultraviolet light incident on the packaging container is between 2000 mW sec cm ^"2 (20 kJ m ^"2 ) and 1000 mW sec cm ^"2 (100 kJ m ^"2 ), wherein the ultraviolet light has a wavelength between about 160 and about 280 nm and preferably an intensity maximum at 185 nm and / or an intensity maximum at 254 nm. 8. A method for extending the shelf life of perishable agricultural products and/or foodstuffs in a packaging container, in particular according to one of claims 1 to 7, characterized in that the agricultural products or foodstuffs are washed with ozone-containing water before being placed in the packaging container. 9. The method according to claim 8, characterized in that the washing water has an ozone content between 2 and 20 mg/l, preferably an ozone content between 4 and 10 mg/l, in particular an ozone content between 6 and 8 mg/l. 10. Packaging container (10) containing perishable agricultural products and/or foodstuffs produced according to the method according to one of claims 1 to 9, wherein in the closed packaging container (10) the agricultural products or foodstuffs and a modified atmosphere are included, characterized in that the modified atmosphere has an increased oxygen concentration compared to normal ambient air. 1. Packaging, in particular for carrying out the method according to one of claims 1 to 9, with a packaging container (10), which is designed to hold perishable agricultural products and / or food and to create a modified atmosphere in the packing space delimited by it, essentially airtight lockable and provided with a gas passage device (30, 40, 50) for allowing gases to escape from the packing space, which are generated by the residual metabolic respiration of the agricultural products or foodstuffs contained in the packaging container (10), characterized in that the gas passage device (30 , 40, 50) is designed as a flat film structure which forms at least a portion of the wall of the packaging container (10). 12. Packaging according to claim 11, characterized in that the gas passage device (30, 40, 50) comprises a semi-permeable plastic film (30) which is designed such that it has a gas permeability of between 1,000 cm ³ for molecular oxygen over its entire surface m ^'2 day ^'1 (1.16 ^* 10 ^'8 m sec ^'1 ) and 10O00 cm ³ m ^'2 day ^"1 (1.16 * 10 ^"7 m sec ^"1 ), preferably a gas permeability between 3O00 cm ³ m ^'2 day ^"1 (3.5*10 ^"8 m sec ^"1 ) and 6'400 cm ³ m ^"2 day ^"1 (7.4*10 ^"8 m sec ^'1 ) and a gas permeability for carbon dioxide of between 3O00 cm ³ m ^'2 day ^'1 (3.5*10 ^'8 m sec ^'1 ) and 30O00 cm ³ m ^'2 day ^'1 (3.5 ^* 10 ^'7 m sec ^'1 ), preferably a gas permeability between 12O00 cm ³ m ^"2 day ^"1 (1.39 *10 ^'7 m sec ^'1 ) and 16O00 cm ³ m ^'2 day ^'1 (1.86*10 ^'7 m sec ^'1 ). 13. Packaging according to claim 11 or 12, characterized in that the gas passage device (30, 40, 50) comprises a film (30) composed of at least two interconnected layers (32, 34) with at least one region (40) defining a pocket. 50), in which the the two film layers (32, 34) are not connected to one another and a pressure-sensitive sealant (46, 56) is arranged between the two film layers (32, 34), with perforations in the pocket area (40, 50) in the two film layers (32, 34). (41, 42, 43, 44, 51, 52, 53, 54) are designed such that they are permeable to gas, but essentially impermeable to the sealant (46, 56), so that overall in the pocket area (40, 50 ) a gas pressure relief valve is formed. 1 . Packaging according to claim 13, characterized in that the pressure-sensitive sealant (46, 56) is a gel-like mass (46, 56). 15. Packaging according to claim 14, characterized in that the perforations (41, 42, 43, 44, 51, 52, 53, 54) are each formed at locations offset from one another in the two film layers (32, 34). 16. Packaging according to claim 14 or 15, characterized in that an antibacterial substance is added to the gel-like mass (46, 56). 17. Packaging according to one of claims 14 to 16, characterized in that an ethylene-binding substance is added to the gel-like mass (46, 56). 18. Packaging according to one of claims 11 to 17, characterized in that at least one part of the wall of the packaging container (10) is designed such that in this part the packaging container wall is well permeable to ultraviolet light. 19. Packaging according to one of claims 11 to 18, characterized by a design of the packaging container (10) such that it is suitable for cooking the agricultural products or foodstuffs contained in the closed packaging container (10) in a microwave oven. 20. Packaging according to claim 19, characterized in that it further comprises a hydrogel mass arranged in the packaging container (10), which releases water when heated. 21. Packaging according to one of claims 11 to 12, characterized in that it further comprises a desiccant arranged in the packaging container (10).