A machine for assembling a modified atmosphere package

Abstract

A machine for assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a lid to close the opening, is described. The machine comprising a frame, a lower die plate attached to the frame and comprising a seat to receive and hold a container, a top die plate attached to the frame and comprising a lid holding module, a vertical actuator configured to vertically adjust the top die plate between a raised position in which it is spaced from said lower die plate and a lowered position in which a lid held by the top die plate is mounted on the container to lid the container. The machine comprises a gas flushing module configured to inject gas into a container when it is seated in the seat through the opening. The lower die plate is attached to the frame for lateral movement between a first position in which the lower die plate is disposed underneath the top die plate and a second position in which the lower die plate is displaced laterally of the first position. The machine comprises a controller operatively connected to the vertical actuator of the top die plate and the gas flushing module, in which the controller is configured to actuate the vertical actuator and the gas flushing module in sequence to flush the container with a gas and attach the lid to the container to trap the gas in the container.

Description

[0001] TITLE

[0002] A machine for assembling a modified atmosphere package

[0003] Field of the Invention

[0004] The present invention relates to a machine for assembling a modified atmosphere package. The invention also relates to a method of assembling a modified atmosphere package and to a modified atmosphere package.

[0005] Background to the Invention

[0006] Modified atmosphere packaging is a method of preserving packaged perishable products such as perishable food products that involves filling a pack with food, flushing the headspace of the pack with an inert gas such as nitrogen, and then sealing the pack. The modified atmosphere inside the pack inhibits the growth of aerobic microorganisms thereby prolonging the shelf-life of the packaged product.

[0007] There are a variety of modified atmosphere packaging machines with various configurations including batch configuration (employing vacuum conditions either surrounding the packing or within the package) and continuous machines. These machines require significant financial investment due to initial costs and installation and also maintenance and training costs, and this can introduce challenges for small to medium size food enterprises who require the use of modified atmosphere packages to extend the shelf life of food products.

[0008] Traditionally, various types of plastic lidding films are used in MAP products to ensure the selected modified atmosphere is maintained. However, there are various disadvantages associated with the use of films including their susceptibility to breach (exposing the product to air) rendering the MAP processing useless, the use of unsustainable materials, the requirement for very specific heat-sealing techniques to be employed, and the requirement for the MAP packages to have an outer packaging sleeve.

[0009] US 5,534,282 describes a method and device for packaging perishable goods in which the package is made up of a plastics base, lid and web for holding the goods in place in which gas is contained within the package by heat sealing the lid to the base. However, the multiple plastics materials are still unsustainable while heat sealing methods are still required.

[0010] It is an object of the invention to overcome at least one of the above-referenced problems.

[0011] Summary of the Invention

[0012] The objective is achieved by providing a machine that can assemble a modified atmosphere package without the requirement of using a plastic film to lid the container. The machine comprises a lower die plate to hold a container containing a perishable product, an upper die plate to hold an interference or push-fit lid, a vertical actuator to lower the upper die plate to lid the container, and a gas flushing module configured to inject gas into the container just prior to lidding. The use of a push-fit lid that effectively seals the modified atmosphere gas in the container, combined with the assembly machine that injects the modified atmosphere gas into the headspace of the container just before lidding, obviates the need for a film lid providing a more robust package without the need for an outer sleeve. The requirement to use specific heat sealing techniques and machines and is also obviated.

[0013] In a first aspect, there is provided a machine for assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a lid to close the opening, the machine comprising: a frame; a lower die plate attached to the frame and comprising a seat to receive and hold a container; a top die plate attached to the frame and comprising a push-fit lid holding module; and a vertical actuator configured to vertically adjust the top die plate between a raised position in which it is spaced from said lower die plate and a lowered position wherein a push-fit lid held by the top die plate is mounted (e.g. physically pressed) on the container to seal the container and the machine comprises a gas flushing module configured to inject gas into a container when it is seated in the seat through the opening.

[0014] In any embodiment, the lower die plate is attached to the frame for lateral movement between a second position in which the lower die plate is disposed underneath the top die plate and a first position in which the lower die plate is displaced laterally of the second position.

[0015] In any embodiment, the machine comprises a controller operatively connected to the vertical actuator of the top die plate and the gas flushing module, in which the controller is configured to actuate the vertical actuator and the gas flushing module in sequence to flush (a headspace of) the container with a gas and attach the lid to the container to trap the gas in the container.

[0016] In any embodiment, the controller is configured to actuate the gas flushing module for a first time period and actuate the actuator immediately after the first time period has elapsed. In any embodiment, the controller is configured to actuate the gas flushing module for a first time period and actuate the actuator intermediate a start and end of the first time period.

[0017] In any embodiment, the gas flushing module comprises a gas injection outlet configured to inject a gas into the opening of the container.

[0018] In any embodiment, the gas injection outlet comprises a gas injection nozzle.

[0019] In any embodiment, the gas injection outlet is annular.

[0020] In any embodiment, the annular gas injection outlet is disposed above a periphery of the seat.

[0021] In any embodiment, the gas flushing module comprises an annular resiliently deformable baffle disposed above the annular gas outlet to direct gas from the annular gas outlet into the container.

[0022] In any embodiment, in which the gas flushing module comprises a plate assembly attached to the lower die plate over the seat, the plate assembly comprising a lower surface, a top surface, an external sidewall and an internal sidewall defining a central aperture in register with the seat and dimensioned to receive the container, wherein the annular gas outlet is disposed along the internal sidewall.

[0023] In any embodiment, the plate assembly comprises an upper plate with an aperture and a lower plate with an aperture. In any embodiment, the aperture of the lower plate is larger than the aperture of the upper plate. In any embodiment, the annular gas outlet comprises an inner periphery of the lower plate.

[0024] In any embodiment, the annular gas outlet is fully annular. In any embodiment, the annular baffle is disposed on the internal sidewall above the annular gas outlet.

[0025] In any embodiment, the annular baffle has a width that is about 5% to 20% of a width of the central aperture.

[0026] In any embodiment, the annular baffle comprises a polypropylene material.

[0027] In any embodiment, the annular baffle comprises an inner peripheral section and an outer peripheral section.

[0028] In any embodiment, the outer peripheral section is mounted between the upper and lower plates.

[0029] In any embodiment, the inner peripheral section comprises a plurality of radial slits to assist the inner peripheral section deform.

[0030] In any embodiment, the lower die plate comprises a gas supply conduit with a gas outlet disposed on an upper surface of the lower die plate, and the lower surface of the annular insert comprises a gas inlet providing fluid communication between the gas outlet of the lower die plate and the annular gas outlet of the annular insert.

[0031] In any embodiment, in which the top die is coupled to the frame by the vertical actuator.

[0032] In any embodiment, the gas supply conduit is connected to a gas reservoir containing an inert gas.

[0033] In any embodiment, the machine comprises an air extraction device, such as a vacuum extraction device, to extract or pull air from a container prior to flushing. In another embodiment, the invention relates to a method of assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a push-fit lid to close the opening, the method comprising: flushing a headspace of the container with an inert gas; pressing the push-fit lid against the container opening, and forming an interference fit between push-fit lid and the container to fluidly seal the inert gas in the container.

[0034] In any embodiment, the method comprises laterally moving the container between a second position in which the container is disposed underneath the push-fit lid and a first position in which the container is displaced laterally of the second position.

[0035] In any embodiment, the method optionally comprises the step of extracting air from the container, e.g. via a vacuum extraction device, prior to flushing the headspace.

[0036] In a further embodiment, the invention relates to a modified atmosphere package produced by the machine and / or according to the method as hereinbefore defined.

[0037] The invention also relates to a modified atmosphere package comprising a container containing a perishable product, the container having an opening, a headspace between the perishable product and the opening, an atmosphere modified with a flushed inert gas in the headspace and a push-fit lid forming an interference fit with the container to fluidly seal the opening.

[0038] Other aspects and preferred embodiments of the invention are defined and described in the other claims set out below.

[0039] Brief Description of the Figures

[0040] Figure 1 is a front elevational of a machine according to a first embodiment of the invention; Figure 2 is a sectional view of part of the machine of Figure 1 ;

[0041] Figure 3 is a block diagram illustrating a controlling module for the machine according to the first embodiment of the invention.

[0042] Figure 4 is a block diagram illustrating parts of a machine according to the second embodiment of the invention.

[0043] Figure 5 is a rear elevational of a machine according to a third embodiment of the invention;

[0044] Figure 6 is a sectional elevational view of part of the machine of Figure 5; and

[0045] Figure 7 is a perspective view of an annular baffle forming a part of the machine according to the third embodiment of the invention.

[0046] Figures 8A to 8C are detailed sectional views of the operation of the annular baffle during the operation of the machine.

[0047] Figure 9 illustrates a pot and push-fit lid suitable for use with the machine of the present invention.

[0048] Detailed Description of the Invention

[0049] All publications, patents, patent applications and other references mentioned herein are hereby incorporated by reference in their entireties for all purposes as if each individual publication, patent or patent application were specifically and individually indicated to be incorporated by reference and the content thereof recited in full.

[0050] Definitions and general preferences Where used herein and unless specifically indicated otherwise, the following terms are intended to have the following meanings in addition to any broader (or narrower) meanings the terms might enjoy in the art:

[0051] Unless otherwise required by context, the use herein of the singular is to be read to include the plural and vice versa. The term "a" or "an" used in relation to an entity is to be read to refer to one or more of that entity. As such, the terms "a" (or "an"), "one or more," and "at least one" are used interchangeably herein.

[0052] As used herein, the term "comprise," or variations thereof such as "comprises" or "comprising," are to be read to indicate the inclusion of any recited integer (e.g. a feature, element, characteristic, property, method / process step or limitation) or group of integers (e.g. features, element, characteristics, properties, method / process steps or limitations) but not the exclusion of any other integer or group of integers. Thus, as used herein the term "comprising" is inclusive or open- ended and does not exclude additional, unrecited integers or method / process steps.

[0053] As used herein, the term “modified atmosphere package” refers to a container containing a product such as a perishable food product, in which the container is closed with a detachable lid, and in which the headspace of the container has been flushed with a gas configured to preserve the product. The gas may be or comprise an inert gas such as Nitrogen, Carbon dioxide, Oxygen, Helium, Argon, Xenon and Neon.

[0054] As used herein, the term “perishable product” refers to a product, generally a food product, which is liable to decay and therefore has a limited shelf life. Examples of perishable food products include but are not limited to fruits, vegetables, hummus, soups, mousse, meat, poultry, fish, dairy products. As used herein, the term “container” primarily refers to cup-like containers, but the machine of the invention may also be employed with other forms of containers such as tubs and trays. The term “lid” refers to a closure for the opening of the container that is designed to be physically pressed on to the opening of the container to close the opening i.e. a lid that is configured to form an interference fit (also known as pressed or friction fit) with a container when the lid and container are urged, pressed or pushed together hereinafter referred to as a “push-fit” lid. An example of a lid suitable for use in the present invention is shown in Figure 9. This push-fit lid provides an excellent seal to limit loss of modified atmosphere gasses. Other push- fit lids may also be employed although the gaseous seal may not be as good.

[0055] As used herein, the term “lid holding module” refers to a part of the upper die plate that holds the lid of the container. The lid holding module may be formation dimensioned to receive the lid and hold the lid in place by physical interaction, for example friction fitting. Alternatively, the lid holding module may comprise a vacuum module configured upon actuation to draw a vacuum to hold a lid in position.

[0056] As used herein, the term “seat” refers to a part of the lower die plate configured to hold a container in place during gas flushing and lidding. The seat generally comprises an aperture or recess in a top of the lower die plate configured to receive and hold the plate. The aperture is generally dimensioned to support an external periphery of a top of the container such that most of the container is received within the aperture or recess. The aperture may include an annular lip or step configured to engage the external periphery of the top of the container.

[0057] As used herein, the term “gas flushing module” refers to a part of the machine configured upon actuation to supply a modified gas to a headspace of the container when it is disposed in the seat of the lower die plate. The gas flushing module is generally disposed on the lower die plate and comprises a gas injection outlet disposed adjacent to the seat of the lower die plate. It includes a gas line providing fluid communication between the gas injection nozzle and a modified gas storage reservoir. The gas injection outlet may be a discrete gas injection nozzle disposed at a position adjacent a periphery of the seat, or it may be an annular gas injection outlet that extends fully or partially around the periphery of the seat.

[0058] As used herein, the term “controller” refers to a processor comprising circuitry configured to control the actuation of the vertical actuator and gas flushing module in sequence so as to inject modified gas into the headspace of the container shortly prior to or during the actuation of the vertical actuator.

[0059] As used herein, the term “annular resiliently deformable baffle” refers to an annular leaf of material disposed above the annular gas injection outlet that functions to direct modified gas exiting the annular gas injection outlet into the headspace of the container and inhibit modified gas exiting the headspace of the container. It is formed of a resiliently deformable material to allow it to resiliently deform when a container is placed into the seat of the lower die and then spring back into its original position to function as a baffle once the top of the container is in engagement with the seat. A suitable material for the baffle is polypropylene, although other polymer and non-polymer materials may be employed. Generally, the baffle has a width that is about 5% to 20% the diameter of the seat.

[0060] Exemplification

[0061] The invention will now be described with reference to specific Examples. These are merely exemplary and for illustrative purposes only: they are not intended to be limiting in any way to the scope of the monopoly claimed or to the invention described. These examples constitute the best mode currently contemplated for practicing the invention.

[0062] Referring to the drawings, and initially to Figures 1 and 2, there is illustrated a machine for assembling a modified atmosphere package (MAP) according to the invention, indicated generally by the reference numeral 1. The machine comprises a frame comprising four upright supporting legs 2, two upper horizontal supports 3 and two lower horizontal supports 4 spanning between the legs. The lower horizontal supports 4 each comprise a rail 5. The machine comprises an upper die plate 6 attached to the frame and a lower die plate 7 mounted to a carriage 8 that is mounted to the rails 5 for lateral movement along the rails.

[0063] In more detail, the upper die plate 6 is coupled to the frame via a vertical actuator 9 that is configured to lower and raise the upper die plate upon actuation, ideally in a single stroke / action. A PCB and motor housing 10 is also provided and mounted to the frame above the vertical actuator 9. Although not shown, the vertical actuator is operatively coupled to the motor. In this embodiment, the upper die plate comprises a central aperture 12 and a suction cup 13 disposed in the central aperture that is operatively coupled to a vacuum pump (not shown). The purpose of the suction cup 13 is to hold a lid 15 of a container 16 in place on the upper die plate 6. The machine may include an on / off switch for the vacuum pump that is operable by a user. The upper die plate is movable between a first raised position and a second lowered position. In the raised position, it is possible for a user to manually attach a lid to the upper die plate where it is held in position by the suction cup.

[0064] The lower die plate 7 comprises a seat to receive a container 16, in this case a square aperture 21 dimensioned to receive a square container with an open top 17. The container 16 has an external lip 22 that extends around a peripheral surface of the container about 2cm under the open top of the container. The square aperture 21 is dimensioned to abut the external lip 22 and hold the container in the seat. The lower die plate 7 also includes a gas flushing module configured to inject a modified atmosphere gas into a headspace of the container when it is seated in the seat through the opening. In this embodiment, the gas flushing module comprises a gas injection nozzle 25 that projects upwardly from a top surface of the lower die plate and has an outlet 26 disposed above the open top of the container when seated in the seat configured to direct gas into the open top of the container. The gas injection nozzle 25 is flu idical ly connected to a pressurised gas container for the modified atmosphere gas (not shown) via a gas line comprising an actuatable valve (not shown).

[0065] In more detail, the carriage 8 (and lower die plate 7) are laterally movable between a first position in which the lower die plate is displaced laterally with respect to the upper die plate 6, and a second position in which the lower die plate is positioned directly under the upper die plate. It will be appreciated that a user may place a container in the seat of the lower die plate when the carriage is in the first position, and then move the carriage to the second position for a capping operation. The machine may include a motor operatively coupled to the carriage to effect lateral movement of the carriage between the first and second positions upon actuation.

[0066] In another embodiment of the invention, the machine can comprise an air extraction device, such as a vacuum extraction device, to extract or pull air from a container prior to flushing.

[0067] Use of the machine generally comprises the following steps:

[0068] 1 . With the carriage in the first position, a container containing a perishable product is placed in the seat of the lower die plate.

[0069] 2. The lower carriage is then moved laterally until the lower die plate is disposed directly under the upper die plate

[0070] 3. With the upper die plate in the raised position, the vacuum pump is actuated and a lid for the container is attached to the suction cup.

[0071] 4. The valve for the modified atmosphere is opened to flush gas into the headspace of the container.

[0072] 5. The motor for the vertical actuator is then actuated and the vertical actuator lowers the upper die plate down towards the lower die plate to attach the lid on the opening of the container held in the seat of lower die plate. The lid is a push-fit lid designed to have an interference or friction fit to the open top of the container. Generally, the interference fit can be configured or calibrated to form a discernible snap- or push-fit (e.g. an audibly or mechanically discernible snap- / push-fit) with the container. The force of the interference fit can also be tailored or set so that the lid can press tightly onto the container with sufficient force to form a fluid-tight seal Accordingly, when the upper die plate is retracted upwardly, the lid remains sealably attached under the interference fit to the container trapping the modified atmosphere gas inside.

[0073] The vertical actuator can be activated during the gas flushing process i.e. between the commencement and end of gas flushing such that vertical actuator movement and gas flushing can be performed concurrently.

[0074] Accordingly, the method of assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a push-fit lid to close the opening, comprises the steps of: flushing a headspace of the container with an inert gas; pressing the push-fit lid against the container opening, and forming an interference fit between push-fit lid and the container to fluidly seal the inert gas in the container.

[0075] Where an air extraction device is present, the method can also comprise the step of extracting air from the container, e.g. via a vacuum extraction device, prior to flushing the headspace.

[0076] The resultant modified atmosphere package therefore comprises a container containing a perishable product, the container having an opening, a headspace between the perishable product and the opening, an atmosphere modified with a flushed inert gas in the headspace and a push-fit lid forming an interference fit with the container to fluidly seal the opening.

[0077] Figure 3 illustrates an optional controlling module 30 for the invention comprising a microprocessor 31 comprising controlling circuitry operatively connected to the motor for the vertical actuator 9, and the valve for the modified atmosphere gas line. The microprocessor is configured to perform the following functions in sequence:

[0078] (1) actuate the valve to flush the headspace of the container with a modified atmosphere gas; and

[0079] (2) actuate the vertical actuator to lower the upper die plate to lid the container and raise the upper die plate when lidding is complete. Generally, the second step is performed 1 to 5 seconds after the first step, although both steps may be started simultaneously.

[0080] Figure 4 illustrates a second embodiment of the machine of the invention is which parts described with refence to the previous embodiments are assigned the same reference numerals. In this embodiment, the machine, indicated generally by the reference numeral 40, comprises a first sensor 41 disposed on the lower die plate and configured to detect when a container has been placed in the seat of the lower die plate, and a second sensor 42 configured to detect when the carriage is in the second position with the lower die plate disposed under the upper die plate. In this embodiment, the microprocessor 31 is operatively connected to the first sensor 41 and second sensor 42 and configured to perform the following functions in sequence:

[0081] (1 ) detect using the first sensor 41 when the seat of the lower die plate has received a container correctly in position;

[0082] (2) once a container has been detected, actuate a motor to move the carriage from the first position to the second position;

[0083] (3) detect using the second sensor 42 the presence of the carriage in the second position;

[0084] (4) upon detection of the carriage in the second position, actuate the valve to flush the headspace of the container with a modified atmosphere gas; and

[0085] (5) actuate the vertical actuator to lower the upper die plate to lid the container and raise the upper die plate when lidding is complete. Generally, step (5) is performed 1 to 5 seconds after step (4), although both steps may be started simultaneously. Referring to Figures 5 to 8, a machine according to a third embodiment of the invention is illustrated, in which parts described with reference to the previous embodiments are assigned the same reference numerals. In this embodiment, the machine 50, and its controlling module, are substantially identical to that of the embodiments described previously except for the lower die plate and gas flushing module. In this embodiment, the gas flushing module comprises a plate assembly 51 configured for mounting to a top surface of the lower die plate 7 and having an aperture 52 dimensioned to align with the aperture 21 in the lower die plate 7. The plate assembly 51 comprises an upper plate 52 and lower plate 53 and an annular baffle 54 mounted between the upper plate and lower plate along a periphery of the aperture 52. The lower die plate 53 includes a modified atmosphere gas conduit having one or more gas inlets disposed on a lower surface of the plate and an annular gas outlet disposed around the aperture 52. The annular gas outlet functions to flush the container with modified atmosphere gas all around the periphery of the opening of the container.

[0086] Figures 7 and 8 illustrate the annular baffle 54 and its function. It is formed of a flexible polypropylene polymer and has an outer peripheral part 56 which is sandwiched between the upper and lower plates of the plate assembly 51 , and an inner peripheral part 57 that functions as a deformable baffle. The inner part may include radial slits to help the inner peripheral part deform. Figures 8A to 8C illustrate how the baffle functions to improve the gas flushing of the container. In Figure 8A, the baffle 54 is shown in a relaxed configuration, with the inner peripheral section 57 extending radially horizontally inwards. In Figure 8B, a container 16 with an annular flange 22 is shown being inserted into the seat in the lower die plate 7, where the inner peripheral part 57 is pushed downwardly by the flange 22 of the container 16. In Figure 8C, the container 16 has been fully seated with the flange 22 of the container 16 sitting on a lip 59 of the lower die plate 7 with the result that the inner peripheral part 57 of the annular baffle 54 springs back to the horizontal un-tensioned position shown. In this position, the inner peripheral part 57 is disposed above the annular gas outlet and functions as a baffle to direct gas exiting the annular gas outlet into the headspace of the container (illustrated with arrow marked A).

[0087] Figure 9 illustrates a pot and push-fit lid suitable for use with the machine of the present invention.

[0088] Although not illustrated herein, it will be appreciated that the upper die plate does not require a suction cup and may be configured to hold the lid by a press-fitting engagement.

[0089] Equivalents

[0090] The foregoing description details presently preferred embodiments of the present invention. Numerous modifications and variations in practice thereof are expected to occur to those skilled in the art upon consideration of these descriptions. Those modifications and variations are intended to be encompassed within the claims appended hereto.

Claims

CLAIMS:1 . A machine for assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a lid to close the opening, the machine comprising: a frame; a lower die plate attached to the frame and comprising a seat to receive and hold a container; a top die plate attached to the frame and comprising a push-fit lid holding module; and a vertical actuator configured to vertically adjust the top die plate between a raised position in which it is spaced from said lower die plate and a lowered position wherein a push-fit lid held by the top die plate is physically pressed on the container to seal the container and the machine comprises a gas flushing module configured to inject gas into a container when it is seated in the seat through the opening.

2. A machine according to Claim 1 , in which the lower die plate is attached to the frame for lateral movement between a second position in which the lower die plate is disposed underneath the top die plate and a first position in which the lower die plate is displaced laterally of the second position.

3. A machine according to Claim 1 or 2, including a controller operatively connected to the vertical actuator of the top die plate and the gas flushing module, in which the controller is configured to actuate the vertical actuator and the gas flushing module in sequence to flush the container with a gas and attach the lid to the container to trap the gas in the container.

4. A machine according to Claim 3, in which the controller is configured to actuate the gas flushing module for a first time period and actuate the vertical actuator immediately after the first time period has elapsed.

5. A machine according to Claim 3, in which the controller is configured to actuate the gas flushing module for a first time period and actuate the vertical actuator intermediate a start and end of the first time period.

6. A machine according to any preceding Claim, in which the gas flushing module comprises a gas injection outlet configured to inject a gas into the opening of the container.

7. A machine according to any of Claims 1 to 5, in which the gas flushing module comprises an annular gas injection outlet.

8. A machine according to Claim 7, in which the gas injection outlet is fully annular.

9. A machine according to Claim 7 or Claim 8, in which the annular gas injection outlet is disposed above a periphery of the seat.

10. A machine according to any of Claims 7 to 9, in which the gas injection outlet comprises a gas injection nozzle.

11. A machine according to any of Claims 7 to 10 in which the gas flushing module comprises an annular resiliently deformable baffle disposed above the annular gas outlet to direct gas from the annular gas outlet into the container.

12. A machine according to any of Claims 7 to 11 , in which the gas flushing module comprises a plate assembly attached to the lower die over the seat, the plate assembly comprising a lower surface, a top surface, an external sidewall andan internal sidewall defining a central aperture dimensioned to receive the container, wherein the annular gas outlet is disposed along the internal sidewall.

13. A machine according to Claim 12, in which the plate assembly comprises an upper plate with an aperture and a lower plate with an aperture.

14. A machine according to Claim 13, in which the aperture of the lower plate is larger than the aperture of the upper plate.

15. A machine according to any of Claim 12 to 14, in which the annular gas outlet comprises an inner periphery of the lower plate.

16. A machine according to any of Claims 11 to 15, in which the annular baffle is mounted to the internal sidewall above the annular gas outlet.

17. A machine according to any of Claims 11 to 16, in which the annular baffle has a width that is about 5 to 20% of the width of the opening of the container.

18. A machine according to any of Claims 11 to 16, in which the annular baffle comprises a polypropylene material.

19. A machine according to any of Claims 11 to 18, in which the annular baffle comprises an inner peripheral section and an outer peripheral section.

20. A machine according to any of Claims 11 to 19, in which the outer peripheral section is mounted between the upper and lower plates.21 . A machine according to any of Claims 11 to 18, in which the inner peripheral section comprises a plurality of radial slits to assist the inner peripheral section deform.

22. A machine according to Claim 12, in which the lower die plate comprises a gas supply conduit with a gas outlet disposed on an upper surface of the lower die plate, and the lower surface of the annular insert comprises a gas inlet providing fluid communication between the gas outlet of the lower die plate and the annular gas outlet of the annular insert.

23. A machine according to Claim 22, in which the top die is coupled to the frame by the vertical actuator.

24. A machine as claimed in Claim 22 or Claim 23, in which the gas supply conduit is connected to a gas reservoir containing an inert gas.

25. A method of assembling a modified atmosphere package of the type comprising a container containing a perishable product and having an opening, and a push-fit lid to close the opening, the method comprising: flushing a headspace of the container with an inert gas; pressing the push-fit lid against the container opening , and forming an interference fit between push-fit lid and the container to fluidly seal the inert gas in the container.

26. A method as claimed in Claim 25, comprising laterally moving the container between a second position in which the container is disposed underneath the push- fit lid and a first position in which the container is displaced laterally of the second position.

27. A modified atmosphere package comprising a container containing a perishable product, the container having an opening, a headspace between the perishable product and the opening, an atmosphere modified with a flushed inert gas in the headspace and a push-fit lid forming an interference fit with the container to fluidly seal the opening

Images