Introduction to the invention Field of the Invention

This invention relates to an oxygen absorbing food packaging inclusion, in the form of a water impermeable but water vapour and gas permeable envelope, containing water vapour or hydrogen activated, finely particulate compounds.

This device has been designed as an active inclusion, for use, in the presence of free, aqueous liquids, within the caps or closures of retail drinks packaging, in order to establish and maintain a stable, oxygen free atmosphere within the headspace of the packaging concerned.

Description of the Related Art in the case of beverages, such as beers and wines, soft drinks, fruit juices and some dairy based drinks, the presence of oxygen, even at very low levels, within the retail packaging, whether bottles, cans or cartons, can have a significant adverse affect on the quality of the product, to the point where it is no longer acceptable.

The presence of oxygen can first be reduced by displacing with nitrogen any dissolved oxygen in the product concerned and then employing, at packing, a nitrogen back- flush to ensure the minimum level of oxygen within the head space.

This process, however, can not displace all of the oxygen and with containers other than glass, there is also the potential continuous migration of oxygen, by diffusion down a concentration gradient, from the surrounding ambient atmosphere, through the packaging, both into the head space and into the product itself. The deployment of those oxygen absorber, or 'scavenger' packaging inclusions currently in the market place, could be effective in removing, very largely, the oxygen within the head space atmosphere and as a consequence, that dissolved in the product itself and thereafter in maintaining oxygen at low residual levels.

The above inclusions, however, are unable to be deployed in the presence of free aqueous liquids as their structure, in terms of the outer envelope, which retains the active oxygen absorbing fill material, is porous to liquid water.

The inundation in aqueous liquids, whether it be partial or temporary, of the active oxygen absorbing fill materials in question, will either severely reduce their efficacy or render them entirely ineffective. Apart from the efficacy of the active oxygen absorbing fill materials under these conditions, there is also the issue of the 'leaching' of the chemical components of these materials into the product itself, especially under low pH conditions, which many of the aqueous liquid foods and beverages concerned provide. Under these conditions, of those oxygen scavengers, currently commercially available and designed for deployment within food products, the range of fill material formulations represented all present difficulties in meeting the permitted maximum migration levels as detailed in EC Directive 97/48/EC, as required by current and forthcoming EU legislation and EFSA regulations.

Thus, as far as the inventor is aware, there is no oxygen scavenger available that complies with the EC directive for inclusion in food products containing liquids.

Summary of Invention

According to the invention, there is provided a device according to claim 1. The device has been designed to overcome the above problem and accommodate those active, oxygen absorbing fill material formulations in question, by enabling them to perform effectively in the presence of free water, under conditions of partial or temporary inundation, without the possibility of components of the fill material formulation, or reaction products migrating into the food products concerned.

A water impermeable membrane/layer/film may be one that provides a fully effective barrier to the passage of water, either as a free liquid or as an aqueous solution and its associated dissolved solutes.

In particular, in the context of foodstuffs, a water impermeable membrane, layer or film may be one that complies with EC Directive 97/48/EC, to Commission regulation no. 10/201 1. This directive requires that the membrane, layer or film is impermeable to liquid water and any associated dissolved solvents, when tested with each one of the following food simulants: -

Distilled water

3% (w/v) acetic acid in an aqueous solution

10% (v/v) ethanol in an aqueous solution

95% (v/v) ethanol under immersion for 10 days at 20°C. The test is passed if the Overall Migration Limit (i.e. maximum total migration across the membrane) is met. This limit for Plastics is10 mg/dm ² . For further details of the required tests, see the relevant standards.

The device may contain as the fill material any one of a number of fill material formulations, including for example those currently available in commercial oxygen 'scavenging' food packaging inclusions.

Suitable fill materials include as the active component either finely comminuted iron metal, ascorbic acid, calcium ascorbate, sodium ascorbate, sodium erythorbate or finely comminuted palladium metal, being designed to establish and maintain an oxygen free atmosphere within the headspace of bottles, sachets or cartons of aqueous liquid foods such as beverages. A particular benefit of the invention is that it allows the use of finely comminuted iron, which is a relatively inexpensive material.

The above fill material formulations, in terms of the percentage composition of the constituent compounds, are designed to effect the pack atmosphere control required and are thus specific to the product packed and will therefore vary from product to product.

The respective weights of the above fill material formulations, are designed to effect the shelf life required and are thus specific to the product packed and will therefore vary from product to product.

In order to retain fully the fill material formulation selected, both dry and hydrated, when in contact with food and in the presence of free, liquid water, the envelope of the device may be fabricated from a bi-laminate material, consisting of a porous support layer and a liquid water impermeable layer. The liquid water impermeable layer may have a water vapour transmission rate WVTR in the range of 10g- 200g/m ² /24hr@23°C & 85%relative humidity and an oxygen transmission rate OTR in the range of 650cm ³ -20,000cm ³ /m ² /24hr/bar@23°C. The envelope material is designed to allow the transmission of water vapour, oxygen and hydrogen at levels that enable the respective fill material formulations to perform optimally.

In particular embodiments, the liquid water impermeable layer may be a water impermeable layer of polyamide (PA) film, with a thickness of 8μηη - 20μηη. The gauge of PA film, deployed in the laminate, is determined by the WVTR and OTR required by the performance demands of the fill material formulation imposed by the packed product in question and will vary from product to product. A variety of possible supports is possible. In one embodiment, the support is a non- woven, opaque 45 g/m ² -55g/m ² polyethylene fabric bonded, with a polyurethane adhesive, to the liquid water impermeable layer.

In embodiments, the water vapour and gas permeable layer of a PA film is permeable to water vapour, oxygen and hydrogen at levels sufficient to prevent these gas becoming a limiting factor in the optimal performance of any of the respective fill material formulations.

The selection of the gauge of the water vapour and gas permeable layer of a PA film employed may be determined by the performance requirements, of any of the respective fill material formulations, imposed by the packed aqueous liquid products in question and will vary from product to product.

The envelope of the oxygen absorbing device preferably retains fully the fill material formulation selected, both dry and hydrated, thus preventing entirely the migration, from the device and into the food, of components of the fill material formulation or any reaction products.

The envelope of a composite material may be a thermoformed, plano-convex, shallow, rectangular or discoid container, the dimensions of which are determined by the mass of fill material formulation required to meet the particular oxygen absorption demands of the packed product concerned.

In embodiments, he envelope of a composite material is a thermoformed, plano- convex, shallow, rectangular or discoid container, sealed with an APET lidding film, carrying a self adhesive layer with peelable backing strip and retains fully the fill material formulation selected, both dry and hydrated, when in contact with food and in the presence of free, liquid water, preventing entirely the migration of components of the fill material formulation or reaction products from the device.

Brief Description of Drawing

An embodiment of the invention will now be described, purely by way of example, with reference to the accompanying Figure 1 , which shows a section through an embodiment of the invention. The drawing is schematic and not to scale.

Detailed Description

Embodiments of the invention will now be described, purely by way of example.

A first embodiment includes an oxygen scavenger with an outer envelope 4, 6 and a fill material 2. The outer envelope is made of two layers, a water permeable support layer 4 on the inside and a liquid water impermeable layer 6 on the outside. Alternative embodiments may reverse the order of layers.

The device has been designed to function with the range of fill material formulations. Some such formulations may be used as high capacity oxygen absorbers in commercially available, active food packaging inclusion products. Such absorbers include: -

The above fill material formulations can be in either loose particulate or 'solid state' format, where, in the latter, the compounds are bound within in an inert matrix.

Of the range of fill material formulations detailed above, all but the palladium metal (Pd) require water in order to react with oxygen and remove it from the atmosphere.

The Pd metal, on the other hand, in the presence of hydrogen acts as a catalyst, combining the former gas with oxygen, effectively removing the latter from the headspace in the form of water vapour, as the reaction product.

The Pd metal has the same general requirements of the device as do the other oxygen scavenging reactants detailed above, with the exception that, in this case, rather than allowing its inward diffusion, water vapour is instead required to diffuse freely out from within the envelope of the device, into the headspace of the packaging concerned, in order to prevent any build-up of pressure within the device, leading to the rupture and loss of integrity of the envelope.

To meet these requirements and allow the fill material formulations to perform optimally, the envelope of the device is designed to have a water vapour transmission rate (WVTR) and an oxygen transmission rate (OTR) that are both high enough to avoid becoming limiting factors in the oxygen absorbing performance of these fill materials.

This is achieved by employing a polymer membrane with both a relatively high WVTR and a relatively high OTR as the liquid water impermeable layer within the device envelope.

The polymer membrane selected is a polyamide (PA) film 8μ - 20μίη thickness, which liquid water impermeable and has a WVTR in the range of 10g-200g/m2/24hr@23°C & 85%RH and an OTR in the range of 650cm ³ -20,000cm ³ /m ² /24hr/bar@23°C. The gauge of PA film, within the range 8μ - 20μ, selected for inclusion in the laminate is determined by the WVTR and OTR required by the performance demands of the fill material imposed by the packed product in question and will vary from product to product.

The specific selection of PA as the membrane polymer is determined by its unique property of having the combination of both relatively high WVTR and OTR performances that are capable of meeting the requirements for the activation and sustained reaction of the fill material formulations listed. In other words, by using a relatively thin PA film it is possible to prevent liquid water passing through the film whilst retaining sufficient water vapour oxygen throughput.

Other polymers, including polyethylene (PE), alone or in combination, are unable to provide the performance requirements detailed above. The inventor has found that a PE film sufficiently thick to function effectively as a wholly impermeable liquid water barrier fails to pass sufficient water vapour.

At the gauges selected, the PA film is relatively fragile and in order to maintain its integrity and thus avoid perforation, it may be protected and supported by a water vapour support layer. This may be, for example, of a non woven polyethylene (PE) fabric, typically at a density of 45.0g/m ² - 55.0g/m ² , which for preference would be a Tyvek material. This material is not an effective barrier to water vapour, oxygen or hydrogen. The membrane film and the supporting fabric, are bonded together with a polyurethane adhesive, or a material of equivalent properties and performance, the composition and thickness of which will have a negligible effect on either the WVTR or OTR of membrane layer or the laminate in general. The WVTR may be measured by employing a commercially available water permeation analyser such as the MOCON PERMATRAN-W Model 3/33, which is designed to test this property of packaging films and has integral automatic relative humidity generation. The machine measures according to the ASTM standard F - 1249.

The OTR may be measured by employing a commercially available oxygen transmission rate analyser, such as the MOCON OX-TRAN Model 1/50, which is designed to test this property of packaging films. The machine measures according to the ASTM standard F- 1927.

The hydrogen transmission rate of the membrane film, as hydrogen has comparatively a very small molecule, will be significantly greater than that of oxygen through this polymer, exceeding the latter rate by a factor greater than 2, thus adequately exceeding the minimum requirements to provide 2 molecules of hydrogen for 1 of oxygen in the Pd catalyzed reaction.. The manufacture of the device, for deployment as an inclusion within caps and closures of aqueous liquid food or beverage packaging, employs existing technology in the form of a modified lamination process, in which the several components, in web form, are bought together and bonded to produce a single material. During the manufacturing process, the selected fill material formulation, at a predetermined volume or weight, is index-deposited on a wadding fabric based on polypropylene (PP), polyester and cellulose with an acrylate-based binding aid, or a material combination of similar properties and performance, which is then over-layered with either a (PP) or an amorphous polyethylene terephthalate (APET) 30μ film as the backing sheet and the PA film/non-woven PE fabric laminate as the coverface.

In the application of the coverface laminate, the interior/external relationship between the PA film and the non-woven PE fabric is interchangeable. To complete the manufacture of the device, the compound laminate material produced is then sealed, along the edge of a pre-determined contour, by the alternatives of, heat bonding, ultrasonic welding or dielectric welding and then die-cut, in an indexed operation, to produce the inclusion shapes and sizes required, although the latter will generally be circular.

In this format the device is intended to be fitted within the caps or closures of bottles sachets or cartons of aqueous liquid foods or beverages and perform as an integral part of a 'leak-proof seal.

In an alternative construction of the device, the PA film/non-woven PE fabric laminate material is thermoformed as a shallow concave, rectangular or discoid cavity, into which the fill material is deposited and then lidded with a gas impermeable membrane of APET, or a material of equivalent properties and performance, and sealed by one of the alternatives of heat bonding, ultrasonic welding or dielectric welding

In the above format of the device, the impermeable membrane of APET or a material of equivalent properties and performance, can be overlaid with a die-cut layer of self adhesive with a peelable backing sheet, which allows it to wound on to a reel for subsequent automated dispensing

In the above format, the device can be manufactured using modified, horizontal tray forming and lidding technology.

In the above format, the device can be readily manufactured in a range of sizes

In the above format, the device is intended to be placed and secured, in a pre- determined position, on the inner surface of the primary packaging of the packed food product.

In either format, the dimensions of the device and thus its surface area will reflect both the mass and formulation volume of the fill material required to effect the pack atmosphere control desired, although it is, nevertheless, intended that it will form a relatively discrete an unobtrusive food packaging inclusion. In the manufacture of the device, for deployment as an inclusion within caps and closures, the selected fill material formulation, at a predetermined volume or weight, is index-deposited on to a wadding fabric based on polypropylene, polyester and cellulose with an acrylate-based binding aid, or materials of similar properties and performance, which is then over-layered with a PP or APET 30μ film as the backing sheet and the PA film/non-woven PE fabric laminate as the coverface and sealed by the alternatives of heat bonding, dielectric welding or ultrasonic welding.

In this format, the device can be manufactured by employing existing technology in the form of a modified lamination process, in which the several components, in web form, are bought together and bonded to produce a single material.

In an alternative construction of the device, the envelope material is thermoformed as a shallow concave, rectangular or discoid cavity into which the fill material is deposited. The filled cavities are then overlaid and lidded with a gas impermeable membrane of APET, or a material of equivalent properties and performance, and sealed by one of the alternatives of heat bonding, dielectric welding or ultrasonic welding, as appropriate. In this format, the device can be manufactured employing modified, horizontal tray forming and lidding technology.

In this format, the device is intended to be placed and secured, in a pre-determined position, on the inner surface of the primary packaging of the packed product.

The size and thus the exposed surface area of either of the formats of the device is designed to effect the pack atmosphere control required and is thus specific to the product packed and will therefore vary from product to product. The size and thus the exposed surface area of either of the formats of the device is designed to effect the shelf life required and is thus specific to the product packed and will therefore vary from product to product. Active inclusions within food packaging must, at the very least, meet the overall migration as detailed in EC Directive 97/48/EC, to Commission regulation no. 10/201 1 , using the following food simulants: -

Distilled water

3% (w/v) acetic acid in an aqueous solution

10% (v/v) ethanol in an aqueous solution

95% (v/v) ethanol with immersion for 10 days at 20°C, where the Overall Migration Limit for Plastics is10 mg/dm ² . For further details of the required tests, see the relevant standards.

The applicants have tested a device where the envelope has laminate of a Tyvek (46g/m2) support and a 4μηη thick polyamide liquid water impermeable layer containing as a fill material, finely comminuted Palladium adsorbed on to a polyester mesh at approximately 3g/m2, with an overall fabric weight of 36g/ m2. This device fully meets the requirements of the EC directive.