Patent Publication Number: US-2019193881-A1

Title: Process and apparatus for gas extraction in packaging

Description:
TECHNICAL FIELD 
     The present invention relates to a packaging process using a gas extraction station and a packaging apparatus comprising a gas extraction station. The packaging process includes extraction of gas from a package or from a semi-sealed package in a gas extraction station having a single vacuum chamber. 
     BACKGROUND ART 
     A packaging apparatus can be used to package a food product. The product can be a naked product or a product pre-loaded onto a tray. A tube of plastic wrap can be continuously fed through a bag/package forming, filling and sealing apparatus. The film and the product are joined, for example the product is deposited on the film or the film is wrapped around the product. In some examples, the naked product is fed through an infeed belt. A tube is created around the product by sealing opposite longitudinal edges of the film. Alternatively, the product is placed in the tube and a leading edge of the packaging is sealed. Then the tube is sealed at the trailing edge (at the upstream end) of the package and is severed from the continuously moving tube of packaging. 
     In some embodiments, the tube can be provided as a tube, or be formed from two films or webs sealed longitudinally at two longitudinal edges, or from a single film that is folded over and sealed along its longitudinal edges. In other embodiments, products are loaded into pre-formed bags which are then supplied to a gas extraction station and sealing station. Further, some embodiments can facilitate gas extraction from two or more packages at the same time in the same process step. The latter can be realized, for example, by processing two or more bags at the same gas extraction station or by feeding, in parallel, two or more tubes of film into a packaging apparatus, where the tubes are processed in parallel. 
     Sealing bars can be used to seal the package, wherein a lower bar and an upper bar are moved with respect to one another in order to contact each other, squeezing the packaging material in between and providing one or more seals. The sealing bars typically also form an adjacent seal, which comprises the opposite end of the next following package, thereby providing one semi-sealed (e.g. having an open end) and one sealed package during a single packaging process step. 
     The seals are typically transversally extending regions of packaging material that have been processed to provide a seal between the inside of the packaging and the environment. In the context of this document, whenever extraction of gas is referred to, it is understood that the term “gas” can comprise an individual particular gas or a mixture of gases and can, for example, consist of air (i.e. consist of a mixture of gases corresponding to ambient air). In some embodiments, packages can be flushed with a protective gas (sometimes also referred to as “inert” gas). It is noted that any known protective gas or gas mixture can be used here, for example CO 2 . 
     Gas can be injected into the package in the space between the product and the film at a loading station with or without a first seal closing the pack at the first end thereof (i.e. at a trailing edge). Any remaining gas inside the package after gas or air has been extracted therefrom and after the package has been sealed assures a very low residual level of O 2  inside the package (e.g., a residual level of O 2  of 1% or lower). This is particularly beneficial with respect to protection of perishable products (e.g. cheese with low gassing level during maturation). 
     A packaging apparatus is typically used for numerous different products with respect to the type of product, size, weight, composition, etc. A range of vacuum chamber machines for an application called “soft vacuum” exists, in which a product (e.g. soft or medium hard cheese with holes) is vacuumized in machines based on a two-chamber apparatus. The two chambers are provided with different air pressures and are separated by a dividing wall having a gasket. The first chamber is a vacuumized chamber provided with a vacuum pressure. The second chamber is a vacuumized chamber provided with vacuum pressure that is higher than the vacuum pressure provided in the first chamber and contains the product placed in a bag. 
     Generally, such a setup may entail several limitations. For example, the complexity and cost for the equipment leaves room for improvement due to the many components required. Further, the size of products that can be processed depend upon the size of the second chamber holding the product during packaging. In some applications, it is difficult to provide chambers of sufficient size due to structural limitation of some components (e.g. actuators). Also, maintaining process reliability and durability of components may be difficult with increasing size of components (e.g. chambers, actuators, gaskets) as the size typically impacts wear and tear properties. Additionally, processing times may increase due to vacuumization of larger chambers taking comparably longer time. 
     US 2012/0174531 discloses a packaging machine and a method of forming a vacuum package. A first evacuable chamber is used for accommodating therein a product-accommodating section of a package, whereas a second evacuable chamber is used for accommodating therein an opening section of the package. Pressure gauges measure the pressure in both chambers, and a supply air valve serves to supply air into the first chamber. The disclosure is characterized in that the supply air valve is a control valve and is adapted to be controlled in dependence upon the difference between the pressures which prevail in the first and second chambers and which are measured by means of the two pressure gauges. The disclosure also relates to the fact that a gap is provided in a partition between the two chambers and that an adjuster is provided for varying and adjusting the cross-sectional area of said gap. 
     EP 1564147 describes an apparatus and process for vacuum packaging a product in a bag. The apparatus comprises a cover hinged to a base member, the cover and the base member being provided with upper and lower divider walls cooperatively defining a first vacuum chamber, a second vacuum chamber adjacent to the first chamber, and an aperture connecting the first and second chambers for passing therethrough the neck of the bag. The apparatus further comprises means to evacuate the first and second chambers independently from each other and means to close the receptacle. The apparatus further comprises means to admit air in the first vacuum chamber and the aperture is provided with means to reduce the passage of air from one chamber to the other. The evacuation process includes one or more cycles of alternately removing air from within the first and second vacuum chambers, while in some phases pressure is at least partially restored in the first vacuum chamber. 
     An aim of the present invention is to provide a packaging process that facilitates efficient packaging of products of larger sizes irrespective of the size of a vacuum or processing chamber. A further aim of the present invention is to provide a packaging process that facilitate extraction of gas and/or air from a package—similar to vacuumization achieved by known apparatuses and processes—using one chamber only. In particular, it is an aim of the invention to provide a packaging apparatus capable of executing the packaging process of the invention. 
     SUMMARY OF INVENTION 
     According to the invention, in a 1 st  aspect there is provided a packaging process comprising the steps of providing a semi-sealed package containing a product to be packaged, the semi-sealed package being made from a film and having a first sealed end and a second open end, providing a vacuum chamber including a first member and a second member arranged opposite the first member, the first member and the second member being relatively movable between a first configuration, in which the first and second members are spaced apart from one another, and a second configuration, in which the first and second members are in contact with one another along a perimeter thereof except for at least one opening being formed between the first and second members, adjusting a spacing between the first and second members to bring the first and second members into the first configuration, thereby opening the vacuum chamber, relatively positioning the semi-sealed package and the vacuum chamber such that a terminal portion of the second end is positioned within the vacuum chamber and a non-terminal portion of the second end is positioned outside the vacuum chamber, an intermediate portion of the second end passing through the opening, the intermediate portion extending between the terminal and non-terminal portions of the second end, adjusting the spacing between the first and second members to bring the first and second members into the second configuration, wherein in the second configuration, the first and second members are, except for the opening, substantially sealingly in contact with one another, and the intermediate portion of the second end is received in the opening, creating, within the vacuum chamber, an internal vacuum pressure that is lower than an ambient pressure outside the vacuum chamber, the internal vacuum pressure being selected such as to a) determine a gas flow through the opening causing opposing layers of the film at the second end to maintain a substantially spaced-apart configuration, and b) aspirate both gas from inside the semi-sealed package and gas from an ambient atmosphere through the opening, and creating a second seal on the semi-sealed package at the second end, thereby forming a sealed package containing the product and having first and second sealed ends. 
     According to the invention, in a 2 nd  aspect there is provided a packaging process comprising the steps of providing a sealed package containing a product to be packaged, the sealed package being made from a film and having a first sealed end and a second sealed end, providing a vacuum chamber including a first member and a second member arranged opposite the first member, the first member and the second member being relatively movable between a first configuration, in which the first and second members are spaced apart from one another, and a second configuration, in which the first and second members are in contact with one another along a perimeter thereof except for at least one opening being formed between the first and second members, adjusting a spacing between the first and second members to bring the first and second members into the first configuration, thereby opening the vacuum chamber, relatively positioning the sealed package and the vacuum chamber such that a terminal portion of the second end is positioned within the vacuum chamber and a non-terminal portion of the second end is positioned outside the vacuum chamber, an intermediate portion of the second end passing through the opening, the intermediate portion extending between the terminal and non-terminal portions of the second end, adjusting the spacing between the first and second members to bring the first and second members into the second configuration, wherein in the second configuration, the first and second members are, except for the opening, substantially sealingly in contact with one another, and the intermediate portion of the second end is received in the opening, creating an aperture in the film at the terminal portion of the second end, and creating, within the vacuum chamber, an internal vacuum pressure that is lower than an ambient pressure outside the vacuum chamber, the internal vacuum pressure and the size of the aperture being selected such as to a) determine an expansion of the terminal portion causing opposing layers of the film at the second end to maintain a substantially spaced-apart configuration, and b) aspirate gas into the vacuum chamber from inside the semi-sealed package through the opening and through the aperture. 
     In a 3 rd  aspect according to aspect 1, the step of providing the semi-sealed package comprises positioning a tubular film around the product to be packaged, and creating, at a sealing station, a first seal on the tubular film thereby forming the semi-sealed package containing the product to be packaged. 
     In a 4 th  aspect according to aspect 2, the step of providing the sealed package comprises positioning a tubular film around the product to be packaged, creating, at a sealing station, a first seal on the tubular film, thereby forming a semi-sealed package containing the product, and creating, at the sealing station, a second seal on the tubular film, thereby forming the sealed package containing the product. 
     In a 5 th  aspect according to any one of aspects 1 to 4, the process further comprises creating a longitudinal seal along a film in order to obtain the tubular film. 
     In a 6 th  aspect according to any one of aspects 1 to 5, the step of relatively positioning the package and the vacuum chamber comprises moving the first member of the vacuum chamber and/or moving the second member of the vacuum chamber relative to the other, and moving the package and/or moving the vacuum chamber relative to the other. 
     In a 7 th  aspect according to any one of aspects 1 to 6, the step of adjusting the spacing comprises moving the first member of the vacuum chamber and/or moving the second member of the vacuum chamber relative to the other. 
     In an 8 th  aspect according to any one of aspects 1 to 7, the step of adjusting the spacing comprises providing the opening with a height of 8 to 20 times a thickness of the film. 
     In a 9 th  aspect according to any one of aspects 1 to 8, the step of adjusting the spacing comprises providing the opening with a height of between 0.3 mm and 1.0 mm, optionally providing the opening with a height of 1 mm or less, preferably 0.8 mm or less, most preferably 0.5 mm or less. 
     In a 10 th  aspect according to any one of aspects 1 to 9, the step of creating the internal vacuum pressure within the vacuum chamber comprises creating an internal vacuum pressure of between 800 mbar and 500 mbar, preferably between 750 mbar and 525 mbar, most preferably between 700 mbar and 550 mbar. 
     In an 11 th  aspect according to any one of aspects 1 to 10, the process further comprises providing the inside of the film and/or the package with a protective gas, optionally the protective gas substantially consisting of CO 2 . 
     In a 12 th  aspect according to any one of aspects 1 to 11, the process further comprises providing a second vacuum chamber and, optionally, operating the second vacuum chamber substantially in parallel to the vacuum chamber. 
     In a 13 th  aspect according to aspect 12, the steps of adjusting the spacing between the first and second members of the vacuum chamber to bring the first and second members into the first configuration, thereby opening the vacuum chamber, and adjusting a spacing between first and second members of the second vacuum chamber to bring the first and second members of the second vacuum chamber into a second configuration, in which the first and second members of the second vacuum chamber are, except for an opening of the second vacuum chamber, substantially sealingly in contact with one another, are performed substantially at the same time 
     According to the invention, in a 14 th  aspect there is provided a device for extracting gas from a semi-sealed package in a packaging apparatus, the semi-sealed package containing a product and having a first sealed end and a second open end, the second end having a terminal portion, a non-terminal portion, and an intermediate portion located between the terminal and non-terminal portions of the second end, the device comprising a vacuum chamber having a first member and a second member arranged opposite the first member, the first member of the chamber and/or the second member of the chamber being movable relative to the other between a first configuration, in which the first and second members are spaced apart from one another, and a second configuration, in which the first and second members are in contact with one another along a perimeter thereof except for at least one opening being formed between the first and second members, and an evacuation means for providing the chamber with an internal vacuum pressure that is lower than an ambient pressure outside the chamber, and a control unit programmed for a) adjusting a spacing between the first and second members and bringing the first and second members in the second configuration such that the intermediate portion of the second end is received in the opening without creating an air-tight seal between the intermediate portion and the first and second members along the opening, wherein, in the second configuration, the first and second members are, except for the opening, sealingly in contact with one another, b) activating the evacuation means to provide the vacuum chamber with the internal vacuum pressure, and c) controlling the internal vacuum pressure for i) allowing a gas flow through the opening causing opposing layers of film at the second end to maintain a substantially spaced-apart configuration, and ii) allowing aspiration of both gas from inside the semi-sealed package and gas from an ambient atmosphere through the opening. 
     According to the invention, in a 15 th  aspect there is provided a device for extracting gas from a sealed package in a packaging apparatus, the sealed package containing a product and having a first sealed end and a second sealed end, the second end having a terminal portion, a non-terminal portion, and an intermediate portion located between the terminal and non-terminal portions of the second end, the device comprising a vacuum chamber having a first member and a second member arranged opposite the first member, the first member of the chamber and/or the second member of the chamber being movable relative to the other between a first configuration, in which the first and second members are spaced apart from one another, and a second configuration, in which the first and second members are in contact with one another along a perimeter thereof except for at least one opening being formed between the first and second members, a puncturing means, an evacuation means for providing the chamber with an internal vacuum pressure that is lower than an ambient pressure outside the chamber, and a control unit programmed for a) adjusting a spacing between the first and second members and bringing the first and second members in the second configuration such that the intermediate portion of the second end is received in the opening without creating an air-tight seal between the intermediate portion and the first and second members along the opening, wherein, in the second configuration, the first and second members are, except for the opening, sealingly in contact with one another, b) controlling the puncturing means to create an aperture in the terminal portion of the second end, c) activating the evacuation means to provide the vacuum chamber with the internal vacuum pressure, and d) controlling the internal vacuum pressure for i) allowing an expansion of the terminal portion causing opposing layers of film at the second end to maintain a substantially spaced-apart configuration, and ii) allowing aspiration of gas into the vacuum chamber from inside the sealed package through the opening and through the aperture. 
     In a 16 th  aspect according to aspects 15, the device further comprises sealing and cutting means, wherein the control unit is further programmed for controlling the sealing and cutting means to provide the package with a seal at the second end between the first end and the aperture. 
     In a 17 th  aspect according to aspect 14, the device further comprises sealing and cutting means, wherein the control unit is further programmed for controlling the sealing and cutting means to provide the package with a seal at the second end. 
     In an 18 th  aspect according to any one of aspects 15 or 16, the puncturing means comprise one of a punch and a heat wire. 
     In a 19 th  aspect according to any one of aspects 15 or 16, the control unit is further programmed for controlling the sealing and cutting means to cut excess film material outside the seal from the second end. 
     In a 20 th  aspect according to any one of aspects 13 to 19, the opening has a width of 1000 mm or less, preferably 500 mm or less. 
     In a 21 st  aspect according to any one of aspects 13 to 20, the control unit is programmed for adjusting the spacing such that the opening has a height of 8 to 20 times a thickness of the film, the control unit optionally being programmed for adjusting the spacing such that the opening has a height of 10 times a thickness of the film or less. 
     In a 22 nd  aspect according to any one of aspects 13 to 20, the control unit is programmed for adjusting the spacing such that the opening has a height of between 0.3 mm and 1.0 mm, optionally the opening having a height of 1 mm or less, preferably 0.8 mm or less, most preferably 0.5 mm or less. 
     In a 23 rd  aspect according to any one of aspects 13 to 22, the opening has a depth of 50 mm or less, preferably 20 mm or less, and more preferably 12 mm or less. 
     In a 24 th  aspect according to any one of aspects 13 to 23, the control unit is programmed for controlling the evacuation means to create an internal vacuum pressure of between 800 mbar and 500 mbar, preferably between 750 mbar and 525 mbar, most preferably between 700 mbar and 550 mbar. 
     In a 25 th  aspect according to any one of aspects 13 to 24, the device further comprises a second vacuum chamber having a respective first member and a respective second member arranged opposite the first member, the first member of the second vacuum chamber and/or the second member of the second vacuum chamber being movable relative to the other between a first configuration, in which the first and second members of the second vacuum chamber are spaced apart from one another, and a second configuration, in which the first and second members of the second vacuum chamber are substantially in contact with one another along a perimeter thereof except for at least one opening of the second vacuum chamber being formed between the first and second members of the second vacuum chamber 
     According to the invention, in a 26 th  aspect there is provided a packaging apparatus comprising a control unit; a gas extraction station coupled to the control unit; an output station; a means for moving coupled to the control unit, the control unit being configured to control the means for moving to move one or more packages, each containing a product to be packaged, towards and through the gas extraction station, and towards the output station; wherein the gas extraction station comprises a device for extracting gas according to any one of aspects 13 to 25. 
     According to the invention, in a 27 th  aspect there is provided a packaging apparatus comprising a control unit, a gas extraction station coupled to the control unit, an output station, means for moving coupled to the control unit, the control unit being configured to control the means for moving to move one or more packages, each containing a product to be packaged, towards and through the gas extraction station, and towards the output station. The gas extraction station comprises a device for extracting gas according to aspect 25, optionally the control unit being configured to control the means for moving to move one or more packages to alternately supply the vacuum chamber and the second vacuum chamber. 
     In a 28 th  aspect according to any one of aspects 26 or 27, the packaging apparatus further comprises a loading station coupled to the control unit, the control unit being configured to control the loading station to position a tubular film around products to be packaged; and a sealing station coupled to the control unit, the control unit being configured to control the sealing station to create one or more seals on the tubular film, thereby creating the one or more packages, each containing one of the products to be packaged, wherein the control unit is configured to control the means for moving to move the one or more packages from the loading station towards and through the sealing station. 
     In a 29 th  aspect according to any one of aspects 26 to 28, the packaging apparatus further comprises a protective gas supply means coupled to the control unit, wherein the control unit is configured to provide the inside of the tubular film with a protective gas, optionally the protective gas substantially consisting of CO 2 . 
     Advantages of the packaging process and the packaging apparatus include that the packaging process can be performed using a single vacuum chamber only. This may also entail a decrease in processing times and/or processing costs. 
     Advantages of the packaging process and the packaging apparatus include that the evacuation station allows for scaling the evacuation procedure in order to optimize the duration of evacuation with respect to an operating rate and/or throughput of remaining operative stations or steps included in the packaging apparatus or process. 
     Advantages of the packaging process and the packaging apparatus further include that products of larger sizes can be efficiently packaged irrespective of the size of the vacuum chamber. 
     Advantages of the packaging process and the packaging apparatus further include that the risk of deterioration of the products (e.g. molding caused by residual oxygen) can be reduced by providing the packages with a protective gas, prior to extraction of gas or air. 
     The packaging process may also facilitate full integration and automation with a horizontal form, fill, and seal (HFFS) apparatus. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1 and 2  depict a first embodiment of a packaging apparatus according to the present invention; 
         FIG. 3  shows a cross-section view of a portion of a gas extraction station in accordance with the present invention; 
         FIG. 4  shows a cross-section view of a portion of a gas extraction station in accordance with the present invention, illustrating a particular profile of terminal portions of first and second members of the vacuum chamber as well as a schematic drawing of gas flow; 
         FIG. 5  shows an isometric view of a portion of a gas extraction station in accordance with the present invention; 
         FIGS. 6 and 7  depict a second embodiment of a packaging apparatus according to the present invention; 
         FIG. 8  shows a cross-section view of a portion of a gas extraction station in accordance with the present invention; 
         FIGS. 9 and 10  show a cross-section view of a gas extraction station in accordance with the present invention; 
         FIGS. 11A to 11I  show a cross-section view of a gas extraction station and associated means for moving in accordance with the present invention, whereas different stages of the gas extraction process are depicted; 
         FIG. 12  shows an isometric view of a third embodiment of a packaging apparatus according to the present invention employing a gas extraction station having two vacuum chambers arranged in parallel; and 
         FIGS. 12A and 12B  show detailed views of the gas extraction station of  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  depict a first embodiment of a packaging apparatus according to the present invention. The packaging apparatus  1  comprises a sealing station  3 , a gas extraction station  35 , and means for moving  30 . Packaging apparatus  1  further comprises a loading station (not shown). Means for moving  30  are configured to move a product  20 , placed inside a film  21 , from the loading station towards and through the sealing station  3  and towards and through the gas extraction station  35 . 
     Typically, products  20  are loaded onto a continuously supplied film, for example supplied from a roll of film (not shown), the film being subsequently longitudinally sealed in order to create a sequence of products  20  placed in tubular film  21 . Optionally, a flusher  34  may be provided in order to flush the inside of tubular film  21  with a protective gas or mixture of gases. The gas or gases may substantially comprise or consist of CO 2 . 
     Products  20  to be packaged assume different states (e.g.  20   a ,  20   b ,  20   c ,  20   d ) of packaging. States  20   a ,  20   b ,  20   c , and  20   d  denote a product  20  being in different packaging stages. For example, state  20   a  denotes product  20  placed inside tubular film  21 , state  20   b  denotes product  20  being contained in a semi-sealed package (i.e. a package having a sealed end and an open end), and states  20   c  and  20   d  denotes product  20  being contained in a sealed package (i.e. a package having two sealed ends, wherein gas in the package being has or has not been extracted). 
     In state  20   a , film  21  is positioned around product  20  or product  20  is positioned in a tubular film  21 . Alternatively, in state  20   a  product  20  is positioned on film  21 , which is subsequently folded over and sealed at its longitudinal edges in order to form a tubular film  21 . This step can be carried out at the loading station and/or at a (separate) longitudinal sealing station. 
     Sealing station  3  comprises an upper sealing and cutting member  31  and a lower sealing and cutting member  32  configured to seal and cut film  21 . Sealing and cutting members  31  and  32  are configured to create a first seal on film  21 , thereby creating a semi-sealed package  23  containing product  20  in state  20   b  and separating semi-sealed package  23  from the continuously supplied film  21  that is sealed at the downstream end of the film. Product  20  in state  20   b  is situated inside film  21  and semi-sealed package  23  comprises a sealed end and an opposite open end. 
     The gas extraction station  35  is configured to create a second seal on film  21  at the second open end of the semi-sealed package, thereby creating a sealed package  24 . In state  20   d , product  20  is situated inside film  21  and sealed package  24  comprises a first sealed end and an opposite second sealed end. The first and second sealed ends can also be situated not directly opposite each other, for example in cases where one of the seals is created at an angle to a longitudinal extension of the package and/or to a lateral extension of the other seal. In another embodiment, the gas extraction station  35  take over the function of sealing station  3  in that while gas is extracted from a semi-sealed package, gas extraction station  35  performs sealing and cutting as described above with respect to sealing station  3 . This concept can be visualized based on the embodiment shown in  FIG. 2 . Instead of operating only on one end of packages  24  in state  20   d  (see on the left hand side of gas extraction station  35 ), it can be imagined that package  23  immediately to the right of gas extraction station  35  (see package/product directly below arrow  30   a ) is sealed at the downstream end of the package at the same time members  351  and  352  are in contact with one another in order to extract gas from the previous package and to seal the package after the extraction. The sealing at both the upstream and downstream ends of gas extraction station  35  could be effected at substantially the same time. 
     Gas extraction station  35  comprises a first (or upper) member  351  and a second (or lower) member  352 , which can be brought from a first configuration, in which the members  351  and  352  are spaced apart from one another (see  FIG. 1 ), into a second configuration, in which the members  351  and  352  are substantially in contact with one another (see  FIG. 2 ). In some embodiments, members  351  and  352  are, in the second configuration, in contact with one another along a perimeter of members  351  and  352 , except for at least one opening that is formed between members  351  and  352 . In a cross section taken along a horizontal plane (i.e. a plane parallel to a horizontal working surface of packaging apparatus  1 , e.g. an upper surface of conveyor belt  30 ), members  351  and  352  may have a substantially rectangular shape. Members  351  and  352  are configured to define, in the second configuration, a vacuum chamber  353 .  FIGS. 1 and 2  show members  351  and  352 , as well as vacuum chamber  353  in (vertical; see above with respect to horizontal) cross section. Thus, front and back sidewalls (i.e. walls parallel to the view plane) are not shown in order to visualize the inside of vacuum chamber  353 . 
     With respect to  FIGS. 1 and 2 , the packaging apparatus  1  further comprises a control unit  50 . The control unit is connected (individual connections are not shown for clarity) to one or more components of the packaging apparatus  1 , including the loading station, sealing station  3 , sealing and cutting members  31  and  32 , means for moving  30 , members  351  and  352 , and flusher  34 . Flusher  34  may be provided in order to flush the inside of the packaging film  21  with a protective gas or mixture of gases. The control unit  50  is further connected to gas extraction station  35 , where gas is extracted from the semi-packaged products in state  20   b  and where they are sealed (and, thus, are brought into state  20   d ). 
     Control unit  50  may further be connected to additional components, such as a hot air or shrink tunnel  33 , where the film material around packaged products  20  in state  20   d  can be additionally shrinked after having been sealed. It is noted that the gas extraction station  35  can comprise any means for gas extraction known in the art.  FIGS. 1 and 2  do not show individual connection lines between the control unit  50  and other components for clarity. It is understood that packaging apparatus  1  can comprise common connection means for connecting control unit  50  to other components, for example electrical, optical, or other connections and/or leads. 
     Control unit  50  can be configured for controlling the transport of products  20  along a predefined path, for example by controlling a motor comprised in means for moving  30  according to a step-by-step motion or according to a continuous motion. The control unit can also control actuators of different components as described below, for example, in order to create transverse seals on the tubular film or in order to actuate members  31 ,  32 ,  351 , and/or  352 . 
     Control unit  50  can comprise a digital processor (CPU) with memory (or memories), an analogical type circuit, or a combination of one or more digital processing units with one or more analogical processing circuits. In the present description and in the claims it is indicated that the control unit is “configured” or “programmed” to execute certain steps. This may be achieved in practice by any means, which allow for configuring or programming the control unit. For instance, in case of a control unit comprising one or more CPUs, one or more programs are stored in an appropriate memory. The program or programs contain instructions, which, when executed by the control unit, cause the control unit to execute the steps described and/or claimed in connection with the control unit. Alternatively, if the control unit is of an analogical type, then the circuitry of the control unit is designed to include circuitry configured, in use, to process electric signals such as to execute the control unit steps herein disclosed. 
     Control unit  50  is connected to a means for evacuating (not shown) and is configured to send and/or receive control signals to/from the means for evacuating. Control unit  50  can further be configured to control the means for evacuating to provide an internal vacuum pressure to vacuum chamber  353 . To this aim, control unit  50  can be configured to control a power driving a vacuum pump connected to vacuum chamber  353 . 
     Control unit  50  can be configured to control the means for moving  30 . For example, control unit  50  can be configured to increase or decrease an operating speed of means for moving  30 . Control unit  50  can further be configured to control the operating speed of means for moving  30  depending on a position of products  20  with respect different components of the packaging apparatus  1  (e.g., with respect to sealing station  3  or gas extraction station  35 ). 
     Control unit  50  can additionally or alternatively be configured for controlling the sealing and cutting members  31  and  32 . The control unit  50  can further be configured to control the sealing and cutting members  31  and  32  depending on a position of products  20  with respect to the means for evacuating and/or the sealing and cutting members  31  and  32 . For example, the control unit  50  can be configured to activate the sealing and cutting members  31  and  32  depending on a position of products  20  and/or tubular film  21  with respect to the outlet and/or sealing and cutting members  31  and  32 . 
     In particular, the control unit  50  can be configured to control one or more components depending on signals sent to and/or received from other components. For example, the control unit  50  can be configured to control an activation of one or more components depending on the position of products  20  and/or tubular film  21  with respect to other components of packaging apparatus  1 . This way, the control unit  50  can activate, for example, the sealing and cutting members  31  and  32  when two subsequent products  20  are in state  20   a , such that between the two products  20  the first seal is created on the film  21  and the film is cut accordingly. 
     After the creation of the first seal and the cutting of film  21 , semi-sealed packages  23  are moved along movement direction  30   a  through the packaging machine, towards and through gas extraction station  35 . In  FIG. 1 , members  351  and  352  are in their first configuration in which a semi-sealed package  23  can be moved through the open vacuum chamber  353 . Before the semi-sealed package  23  exits gas extraction station  35 , the semi-sealed package  23  is positioned such that the second open end thereof is at least partially inside the open vacuum chamber  353 . In detail, it is ensured that the respective product  20  contained in semi-sealed package  23  as well as a non-terminal portion of film  21  at the second open end of semi-sealed package  23  are outside of open vacuum chamber  353 , while a terminal portion of film  21  at the second open end is still inside open vacuum chamber  353 . Consequently, an intermediate portion of film  21  at the second open end of the semi-sealed package and extending between the non-terminal and terminal portions is located between at least a section of members  351  and  352 . 
     Members  351  and  352  are now brought into their second configuration, in which members  351  and  352  are substantially in sealed contact to one another, thereby defining closed vacuum chamber  353 . The contact between members  351  and  352  is substantially sealed (e.g. air-tight), except for an elongated opening at which members  351  and  352  engage the intermediate portion of the second open end of semi-sealed package  23  without creating an air-tight seal along the opening. 
     This configuration facilitates at least the following effects upon extraction of gas from vacuum chamber  353 . On one hand, a gas flow through the opening towards the inside of vacuum chamber  353  is created between opposing surfaces of members  351  and  352  and corresponding surfaces of the intermediate portion of the second open end interposed between members  351  and  352 . This gas flow causes adjacent layers of film at the second end of the semi-sealed package  23  to assume and/or maintain a substantially spaced-apart configuration (i.e. opposite layers of film are pulled apart from one another). On the other hand, gas is not only aspirated from outside vacuum chamber  353  and semi-sealed package  23 , but also from inside semi-sealed package  23 , thereby extracting air from semi-sealed package  23 . Typically, the gas aspirated from the outside is air and the gas aspirated from inside the semi-sealed package is a protective gas or gas mixture, such as CO 2 . This process is described in more detail below. 
     When gas has been extracted from semi-sealed package  23 , a sealing assembly, typically integrated into gas extraction station  35 , creates a second seal at the second open end, thereby sealingly closing the package and transforming the semi-sealed package  23  into a sealed package  24 , which contains product  20  in state  20   d  (see far left of  FIG. 2 ) and from which substantially all inside gas has been extracted. Optionally, an outer portion of excess film material of the second end (which is now sealed) is cut from sealed package  24 . 
     With respect to  FIGS. 1 and 2 , the means for moving  30  can comprise one or more conveyor belts  30 . The one or more conveyor belts are configured to transport the products  20  in states  20   a ,  20   b , and  20   d , for example as packages  22 ,  23 , and  24 , along a pre-defined path through the packaging apparatus  1 . For example, the packaging apparatus may comprise a number of conveyor belts  30  (e.g. three, as shown in  FIGS. 1 and 2 ). A first conveyor belt  30  is configured to transport the products  20  and/or film  21  upstream of the sealing and cutting members  31  and  32 . A second conveyor belt  30  is configured to transport the products  20  and/or packages  22  and  23  downstream of the sealing and cutting members  31  and  32 . And a third conveyor belt is configured to transport the packages  24  downstream of the gas extraction station  35 . 
       FIG. 3  shows a cross-section view of a portion of the gas extraction station  35  in accordance with the present invention. Generally, the inside of vacuum chamber  353  and the ambient atmosphere (e.g. around the chamber and/or the semi-sealed package  23 ) are connected through one or more channels extending along or near and through opening  354 . Here, the different portions of the second open end of the semi-sealed package  23  are shown as terminal portion  236 , intermediate portion  234 , and non-terminal portion  232 . It is noted that “terminal” refers to the outermost portion of film  21  at the second open end of semi-sealed package  23 , which has been cut from continuous film  21  and which has not been sealed (see description of  FIGS. 1 and 2  above).  FIGS. 3, 4, and 5  are not to scale for reasons of clarity. In general, a height of opening  354  is typically 0.3 mm to 1 mm or about 8 to 20 times the thickness of a single layer of film  21 . In some embodiments, the height of opening  354  is 0.8 mm, 0.5 mm, or 0.4 mm. The film  21  typically has a thickness in the range of 30 μm to 60 μm, preferably in the range of 40 μm to 55 μm, most preferably in the range of 45 μm to 52 μm. 
     As shown in  FIG. 3 , members  351  and  352  engage intermediate portion  234  of the second open end without creating an air-tight seal between the inside of vacuum chamber  353  and the ambient atmosphere. The channels between the two volumes (i.e. the volume inside the vacuum chamber  353  and the volume outside thereof) may be created mechanically between members  351  and  352  and the non-terminal portion  232 , the intermediate portion  234 , and/or the terminal portion  236  in order to ensure a possible airflow due to the pressure differential created by means of the extraction of gas from vacuum chamber  353 . In other words, gas or air from outside the semi-sealed package can pass between members  351  and  352  and the non-terminal portion  232  (channels C1), between members  351  and  352  and the intermediate portion  234  (channels C2), and/or between members  351  and  352  and the terminal portion  236  (channels C3). It is noted that the individual spacing of channels does not have to be identical on both (e.g. upper and lower) sides of the film material of the second open end. For example, the size (e.g. height) of a channel C2 between member  351  and intermediate portion  234  (i.e. the channel C2 on the upper side of intermediate portion  234 ) does not have to be identical to the size of a channel C2 between member  352  and intermediate portion  234  (i.e. the channel C2 on the lower side of intermediate portion  234 ). Due to several effects (e.g. force of gravity, turbulences, non-identical pressures and/or pressure variations) acting upon the flexible film material, the dimensions of the channels may vary before, during, and after extraction of gas. The same applies to channels C1 and C3. Further, the spacing between the film material may vary along the length of opening  354 , for example due to an undulating shape of the film material at the second open end of the semi-sealed package. 
     The width of opening  354  may vary according to the application and, preferably is designed to meet the product size with respect to the width of the product or a multiple thereof, in addition to a certain margin. This means that vacuum chamber  353  can be sized to meet the width of the product in the sense that opening  354  largely corresponds to the width of film  21  at the second open end (when brought into a flattened configuration, as shown in  FIGS. 3 and 4 ), whereas the width of the opening should be slightly wider than the film in order to account for positioning or manufacturing tolerances during packaging. It should further be avoided to have large portions of opening  354  unoccupied by film material because of the resulting loss of gas flow resistance in areas adjacent to film material and the subsequent loss in gas flow through the opening in areas occupied by the film material. That said, it is possible to extract gas from two or more semi-sealed packages  23  side by side by providing a vacuum chamber  353  (and, thus, opening  354 ) having a width that is a multiple of the package width or larger (e.g. up to 33% wider; in some embodiments 25% wider). In some examples, gas from three or more semi-sealed packages  23  can be extracted in parallel in a gas extraction station having an operative width of up to 1000 mm (i.e. having an opening being 1000 mm in width). In some embodiments, the gas extraction station has an operative width of (i.e. the opening has a width of) 900 mm. In other embodiments it has a width of 450 mm. In reference to a portion of the opening occupied by film material, the second ends of a number of semi-sealed packages can occupy 70-90% of the opening, preferably 75-80% of the opening. 
     The different effects facilitating extraction of gas from the packages are explained in more detail with respect to  FIGS. 4 and 5 .  FIG. 4  shows a cross-section view of a portion of gas extraction station  35  in accordance with the present invention, illustrating a particular profile of terminal portions of members  351  and  352  as well as a schematic drawing of gas flow. One key issue in extraction of gas from semi-sealed packages is to ensure that the open end of the package is sufficiently open in order to facilitate aspiration of gas from inside the package. In some cases, film material tends to adhere to adjacent film material, thereby temporarily substantially closing the open end of the semi-sealed package and preventing extraction of gas from the package. In other cases, film material partially adheres to adjacent film material, thereby reducing the size of the opening(s) such that aspiration of gas from inside the semi-sealed package is at least partially impaired. 
     One way to separate opposite layers of film or to prevent opposite layers from adhering to one another is to create a transition from a relatively high pressure, low velocity, area (shown as HP/LV on the left at the top of  FIG. 4 ) into a relatively low pressure, high velocity, area (shown as LP/HV) or vice versa, and, optionally, back again (shown as HP/LV on the right). Here, the transition from high to low pressure (or vice versa) as well as the transition from low velocity to high velocity (or vice versa) in combination with excitation of the film material (e.g. due to turbulence and/or gas flow) can cause layers of contacting film material to cease adhesion and be pulled apart from one another by the gas flow pressure differential, the velocity differential, and/or frictional effects. Additionally, the position of the layers of film in the opening can influence the properties of the gas flow in a self-regulating manner. For example, if a channel between a layer of film and one of members  351  and  352  becomes smaller (or larger), the pressure and velocity of gas flowing through the channel changes correspondingly and, thus, may in turn influence the position of the film, thereby changing the size of the channel. 
     The gradient of pressure/velocity changes in transition between HP/LV and LP/HV areas can be modified by providing edges D, F, D′, and/or F′ with corresponding profiles. Modification of the shape of edges D, D′, F, and F′ impacts gas flow in the associated areas and can, for example, facilitate or prevent delamination of gas flow or facilitate or prevent turbulences. The individual effect can be a result of the effects of corresponding shapes on the gas flow (e.g. pressure, velocity, direction, etc.). Edges D and D′ denote entry edges in the figures, while edges F and F′ denote exit edges, with reference to gas flow upon extraction of gas from vacuum chamber  353 . As shown in  FIG. 4 , edges D, F, D′, and F′ can have a substantially rounded shape, for example defined by a radius of between 1 and 5 mm, in some embodiments preferably 2 mm or 2.5 mm. It is noted that edges D, F, D′, and F′ can have the same or different shapes in that, in particular, entry edges D and D′ can have a different shape than exit edges F and F′, but also in that edges D or F of member  351  can have a different shape than edges D′ or F′ of member  352 . 
       FIG. 5  shows an isometric view of a portion of a gas extraction station  35  in accordance with the present invention. Here, a particular profile of members  351  and  352  is illustrated. Parameters which characterize members  351  and  352  as well as opening  354  include: depth C, height B, width A, angle G, and radii D, E, and F. Opening  354  has a height of B of 1 mm or less, preferably between 0.4 and 0.8 mm (e.g. 0.4 mm, 0.5 mm, or 0.8 mm). Opening  354  further has a width of 1000 mm or less (e.g. 900 mm), preferably 500 mm or less (e.g. 450 mm). Opening  354  further has a depth of 50 mm or less (e.g. 45 mm), preferably 20 mm or less (e.g. 20 mm), and more preferably 12 mm or less (e.g. 12 mm). The shape of entry edge D is based on a curvature defined by a radius of 5 mm or less, preferably 2.5 mm or less (e.g. 2.5 mm or 2 mm). The shape of inclination edge E is based on a curvature defined by a radius of 50 mm or less (e.g. 50 mm), preferably 30 mm or less (e.g. 30 mm). Inclination edge E can be present (i.e. the corresponding radius being greater than 0) or not present (i.e. the corresponding radius being equal to 0). The shape of exit edge F is based on a curvature defined by a radius of 10 mm or less (e.g. 9 mm), preferably 5 mm or less (e.g. 2 mm). Corresponding edges D′, E′, and/or F′ (not shown) associated with member  352  can have the same properties as described above with respect to edges D, E, and F, although the individual values do not have to be identical (e.g. edge D being based on a radius of 2.5 mm and edge D′ being based on a different radius). Thickness H pertains to the thickness of film material, whereas H denotes the thickness of two layers of film material since an open end of a semi-sealed package as described comprises at least two layers of film material. A width of the second open end of semi-sealed package  23  or package  24  can be defined by a percentage of A with reference to the width A of opening  354 . The second end of package  23 / 24  can have a width of, for example, 70-90% of A, preferably 75-80% of A. 
     Another effect that predominantly occurs with members  351  and  352  having profiles as described above and with reference to  FIG. 5  pertains to characteristics of gas flow through the opening and along the profiles of members  351  and  352 . It is noted that the cross section of the opening is non-constant along the depth C of the opening (see “C” in  FIG. 5 ) and, in particular, increases from inclination edges E and E′ towards exit edges F and F′. Gas flow along the surfaces of members  351  and  352  tends to follow the shape of the surfaces due to viscosity effects between the gas flow and the adjacent surfaces, as well as the Coand{hacek over (a)} effect. The same effects occur between the gas flow and the surfaces of the film material of package  23 . Since the gas flow between the film material and, for example, member  351  tends to follow the surface (i.e. the shape of the surface) of both the film material and member  351 , the gas flow has to expand and slow, thereby exerting a force upon both surfaces directed towards the gas flow. In other words, the gas flow will pull both the film and the respective member towards one another. As the members  351  and  352  are fixedly held in their respective positions, essentially the layers of film material at the intermediate and terminal portions of the second end are pulled apart from one another. This pulling action creates and/or maintains a channel extending from inside the package towards and through the second end through which gas from inside the package can be evacuated. 
     The individual parameters for achieving the above effects vary depending on the individual application. For example, thicker film material may require a different pressure differential gradient than thinner film material. Further, the values of the different pressures and gas flow velocities are also decisive factors. The following table 1 of examples illustrates different parameter combinations that have proven to be effective with respect to the first embodiment described above. In these examples, an opening of the processed semi-sealed packages was ensured and efficient extraction of gas from the packages was achieved. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Example 1 
                 Example 2 
                 Example 3 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 Opening 
                 Width (A) 
                 900 
                 900 
                 450 
               
               
                   
                 Height (B) 
                 0.5 
                 0.8 
                 0.4 
               
               
                   
                 Depth (C) 
                 20 
                 20 
                 12 
               
               
                   
                 Entry (D) 
                 2.5 
                 2.5 
                 2 
               
               
                   
                 Inclination (E) 
                 30 
                 50 
                 0 
               
               
                   
                 Exit (F) 
                 2 
                 9 
                 2 
               
               
                   
                 Angle (G) 
                 25 
                 15 
                 0 
               
               
                   
                 Pumping  
                 500 
                 800 
                 630 
               
               
                   
                 Capacity m 3 /h 
                   
                   
                   
               
               
                   
                 Differential  
                 350-450 
                 350-450 
                 280 
               
               
                   
                 Pressure mbar 
                   
                   
                   
               
               
                   
                 Coverage  
                 75-80 
                 75-80 
                 75-80 
               
               
                   
                 % (of A) 
                   
                   
                   
               
               
                   
                 Film  
                 40-60 
                 40-60 
                 40-60 
               
               
                   
                 Thickness (μm) 
                   
                   
                   
               
               
                   
                 Material 
                 BK, BB, OSB 
                 BK, BB, OSB 
                 BK, BB, OSB 
               
               
                   
               
            
           
         
       
     
     In general, the described process and apparatus can be used in combination with a large number of known film materials. In some examples, the film materials used have the properties listed in the following table 2 (LD denotes longitudinal direction, TD denotes transversal direction). It is noted that these films are merely examples showing the applicability of the described process and apparatus. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Material 
                 OSB3050 
                 BK3550 
                 BB3050 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Thickness (μm) 
                 50 
                 52 
                 50 
               
               
                 Elastic Modulus LD/TD (kg/cm 2 ) 
                 3000/2800 
                 3000/2800 
                 2000/2000 
               
               
                 ASTM D882 
                   
                   
                   
               
               
                 Elongation at Break LD/TD (%) 
                 140/170 
                 210/220 
                 160/230 
               
               
                 ASTM D882 
                   
                   
                   
               
               
                 Free Shrink 85° C. LD/TD 
                 30/38 
                 35/40 
                 32/40 
               
               
                 (%) ASTM D2732 
                   
                   
                   
               
               
                 OTR 0% RH, 23° C. (cc/m 2 *day) 
                 17 
                 175 
                 17 
               
               
                 ASTM D3985 
                   
                   
                   
               
               
                   
               
            
           
         
       
     
       FIGS. 6 to 8  depict a second embodiment of a packaging apparatus according to the present invention. In general, components operate in the same manner as described above with respect to the first embodiment and as shown in  FIGS. 1 and 2 , unless specifically described otherwise here below. The same reference numerals in  FIGS. 6 and 7  denote components corresponding to those in  FIGS. 1 and 2 . Unless stated otherwise, such components have the same function and properties as described above. 
     Sealing and cutting members  31  and  32  are, in the second embodiment, configured to create not only a first seal on tubular film  21  but also a second seal. In this manner, products  20  placed within tubular film  21  exit the sealing station  3  in state  20   c , namely in a sealed package  24 ′ (instead of state  20   b  and in a semi-sealed package  23 ). A sealed package  24 ′ differs from a sealed package  24  in that gas present in package  24 ′ has not yet been extracted. As shown, means for moving  30  move packages  24 ′ towards and through gas extraction station  35 . Gas extraction station  35  operates essentially similar as described above, although it is adapted to handle sealed packages in the manner described below. After extraction of gas from package  24 ′, thereby transforming package  24 ′ into sealed (and gas-extracted) package  24 , movement means  30  move packages  24  away from gas extraction station  35 . 
     As can be seen in  FIG. 7 , sealed packages  24  are positioned with respect to vacuum chamber  353  such that, upon bringing members  351  and  352  into their second configuration, the second (here sealed) end of package  24 ′ is engaged by members  351  and  352  such that a non terminal portion of the second is positioned outside vacuum chamber  353 , an intermediate portion of the second end is engaged by members  351  and  352 , and a terminal portion of the second end is positioned inside vacuum chamber  353 . The setup is largely identical to what is described above with respect to the first embodiment and the semi-sealed package, with the exception that the second embodiment is configured to process sealed packages. The details of the gas extraction process are described in more detail with respect to  FIGS. 8-10 . 
       FIG. 8  shows a cross-section view of a portion of a gas extraction station in accordance with the present invention. Members  351  and  352  engage the sealed end of a sealed package  24 ′ at an intermediate portion of the second end. It is noted that non-terminal ( 232 ), intermediate ( 234 ), and terminal ( 236 ) portions of a second end of a sealed package correspond to what is shown with respect to a semi-sealed package  23  in  FIG. 3 . For clarity, these portions are not shown in  FIG. 8 . Upon members  351  and  352  being brought into their second configuration, the terminal portion of the second end as well as the remainder of package  24 ′ (outside of vacuum chamber  353 ) is slightly expanded due to the gas present in the intermediate portion of the second end being pushed outwardly both in direction of the terminal portion and the non terminal portion of the second end. In addition to the components described above, vacuum chamber  353  can further comprise first  355  and second  356  holding elements that engage an outermost part of the terminal portion of the second end. This can be done in order to fixedly hold the terminal portion in a particular position within vacuum chamber  353 . 
     A puncturing means  359  is engaged in order to provide the terminal portion with an aperture  241 , thereby providing a potential passage of gas from inside package  24 ′ into vacuum chamber  353 . In general, any puncturing means suitable for puncturing the terminal portion of the second end can be employed here, for example, a punch (e.g. creating a substantially round hole by punching or stamping) or a suitably shaped heat wire (e.g. a horseshoe-shaped heat wire creating a corresponding substantially round hole by thermally cutting the film). The puncturing means are preferably configured to provide the terminal portion of the second end with a hole that prevents (further) rupture of the film material, which can happen, for example, when creating a simple (linear) cut or an opening having sharp corners. Upon extraction of gas from vacuum chamber  353 , the terminal portion expands (see outward pointing double arrows in  FIG. 8 ) due to the pressure differential between the inside of package  24 ′ and the inside of vacuum chamber  353 . The expansion of the terminal portion causes film material of the second end to maintain a spaced apart configuration, thereby ensuring that gas from inside package  24 ′ can flow towards and through the non-terminal portion, the intermediate portion, and the terminal portion of the second end, before being drawn through aperture  241  and into vacuum chamber  353  as indicated by the dashed arrows. In this manner, gas is extracted from package  24 ′, which is subsequently sealed with corresponding sealing means (not shown in  FIG. 8 ). Sealing means can comprise sealing bars as known in the art (e.g. similar to sealing and cutting members  31  and  32 ) and can be, for example, integrated into members  351  and  352  or provided as separate units outside of vacuum chamber  353 , configured to seal package  24 ′ and cut an outer part of the second end from package  24 ′, thereby providing sealed package  24  from which gas has been extracted (see  FIG. 6 ). It is noted that the puncturing of the terminal portion can alternatively be effected after the extraction of gas has begun and while it is ongoing. In this case, the expansion of the terminal portion—which is caused due to the pressure differential and irrespective of aperture  241  being present or not—can serve to counter the action of a punch or other puncturing means, thereby facilitating precise and reliable placement of the puncturing means and creation of aperture  241 . 
       FIGS. 9 and 10  show a cross-section view of a third embodiment of a gas extraction station in accordance with the present invention.  FIGS. 9 and 10  illustrate one of the advantages of the present invention as well as additional components associated to vacuum chamber  353 . Product  20  as shown in  FIGS. 9 and 10  is illustrated as a much larger object than in the remaining figures. It is noted that the size of the vacuum chamber and, thus, the opening  354  merely limits one dimension of the potential size of the products to be processed, namely the width of the package. As shown in  FIGS. 9 and 10 , the size (e.g. length) of a product  20  does not impact the gas extraction process because merely a portion of the sealed (or unsealed) end of the package has to fit into the vacuum chamber  353 , instead of the entire product. Also the height of product  20  has only a negligible impact on the gas extraction process in that the operative height of members  351  and  352 , as well as the clearance between the two members  351  and  352  when in the first configuration can be adjusted accordingly. 
       FIG. 9  shows members  351  and  352  in their first configuration, allowing for a package  24 ′ to be positioned such that the non-terminal, intermediate, and terminal portions of the sealed end of package  24 ′ can be positioned as described above. Additionally, members  351  and  352  are respectively associated with cutting means  357  and  357 ′ as well as sealing means  358  and  358 ′. Adjacent to cutting means  357  and  357 ′, members  351  and  352  exhibit curved shapes for engaging the intermediate portion of the second end of package  24 ′. Sealing means  358  and  358 ′ are arranged adjacent thereto. 
       FIGS. 11A to 11I  show a cross-section view of the third embodiment of a gas extraction station and associated means for moving in accordance with the present invention, whereas different stages of the gas extraction process in accordance with the third embodiment are depicted. The direction of movement of packages through the packaging apparatus is from right to left, corresponding to  FIGS. 1, 2, 6, and 7 . In  FIG. 11A , members  351  and  352  are in the first configuration, such that a sealed package  24 ′ can move along members  351  and  352  into a position where a terminal portion of package  24 ′ is positioned between members  351  and  352  but where the product is positioned outside of the area interested by members  351  and  352 . In  FIG. 11B , an optional step of adjusting the means for moving  30  is illustrated. In some embodiments, the means for moving  30  are adjustable in order to facilitate efficient movement of packages through the packaging apparatus, while assisting in the positioning of the packages with respect to members  351  and  352 . As illustrated, a section of the means for moving can assume a transport configuration in which packages can be moved through station  35  and a gas extraction configuration, in which a package is positioned with respect to members  351  and  352  in order to facilitate extraction of gas from the package. In  FIG. 11C , members  351  and  352  are brought into the second configuration and, as shown in  FIG. 11D , cutting means  357  are activated in order to cut excess film material from the terminal portion of the package, thereby opening the package again. Substantially at the same time as the package is opened (i.e. shortly before or after), chamber  353  is evacuated such that a pressure differential is created between the inside of chamber  353  and the outside atmosphere. In  FIG. 11E  it can be seen that the excess film material has dropped into a receptacle (or is otherwise disposed of) and that gas is extracted from the inside of package  24 ′ (shown in that residual gas between the film and product  20  is reduced). Consequently, the film of package  24 ′ approaches product  20  as gas is extracted.  FIG. 11F  shows the final stages of gas extraction, in which the film lies closely against product  20  and gas has substantially been extracted from the package  24 ′. Subsequently, evacuation of chamber  353  is stopped and package  24 ′ is re-sealed by sealing means  358  and  358 ′. In  FIG. 11G , the sealing means  358  and  358 ′ disengage and in  FIG. 11H , members  351  and  352  assume the first configuration (i.e. chamber  353  is opened), thereby releasing package  24 ′. Optionally, a section of means for moving  30  is adjusted for moving package  24 ′ onwards and/or for receiving a subsequent package.  FIG. 11I  shows how the subsequent package is moved between members  351  and  352  in their first configuration and, thus, through open chamber  353  in order to be positioned as described above. The process then starts over with the subsequent package  24 ′ as described above. 
       FIG. 12  shows an isometric view of a third embodiment of a packaging apparatus according to the present invention employing a gas extraction station  35 ′ having two vacuum chambers  353 ′ arranged in parallel. The gas extraction station  35 ′ of the packaging apparatus  1 ′ includes two vacuum chambers  353 ′ arranged on either side of an infeed belt  30   i . As shown in  FIG. 12 , products  20  can enter the gas extraction station  35 ′ along movement direction  30   a  via an infeed belt, for example in form of pillow packs (i.e. packages  24 ′, preferably flushed with an inert gas and sealed at both ends, that have not yet undergone gas extraction; see also the description of  FIGS. 6 and 7  above). The control unit  50  is configured to control a middle cross conveyor  30   m  to receive packages  24 ′ via the infeed belt  30   i  along movement direction  30   a  and to move the packages  24 ′ selectively either to the left along path  30   a - 1  or to the right along path  30   a - r , respectively onto additional cross conveyors  30   l  or  30   r . A respective vacuum chamber  353 ′ is located to either side of the middle cross conveyor  30   m.    
     The vacuum chamber  353 ′ structurally and functionally corresponds to vacuum chambers  353  as described above. Thus the vacuum chambers  353 ′ may include members  351 ′ and  352 ′ and may be configured to open and close (not shown in  FIG. 12  for clarity) as described in detail above. Additional components, for example actuators configured to move members  351 ′ and/or  352 ′, are not shown in  FIG. 12  for clarity. The packages  24 ′ being moved along paths  30   a - 1  and  30   a - r  can be moved to laterally introduce an upstream end of the package into the open vacuum chambers  353 ′. Subsequently, the vacuum chambers can be closed and evacuation can be performed as described above. In this manner, the two vacuum chambers can be operated in alternating fashion (or substantially parallel and/or independent from one another) and during each operating cycle of a respective vacuum chamber  353 ′ (e.g. opening, introducing upstream end of one or more packages, closing, evacuating, opening again), one or more packages  24 ′ can be evacuated using the respective (e.g. left or right) vacuum chamber  353 ′. It is understood that vacuum chambers  353 ′ can be operated substantially independent from one another, for example in order to account for different evacuation times, packages  24 ′ of different sizes, etc. 
     Substantially upon introduction (e.g. at the same time or shortly before/after) of the upstream end of the package  24 ′ into the opening (see state  20   c  in  FIG. 12 ), the film material at the upstream end can be perforated or pinched in order to facilitate subsequent gas extraction. The perforation can be performed using perforation rollers  360  (see  FIGS. 12A, and 12B ). As the upstream ends of the packages is introduced into the vacuum chamber  353 ′, gas or air from inside the package can be evacuated upon closing of the vacuum chamber  353 ′ as described above. When gas extraction is completed, sealing and cutting is performed as described above, in order to release the now evacuated packages  24 ′ (see state  20   d  in  FIG. 12 ) from vacuum chamber  353 ′. 
       FIGS. 12A and 12B  show detailed views of the gas extraction station of  FIG. 12 . The control unit  50  is operably connected to the middle cross conveyor  30   m , the left cross conveyor  30   l  and the right cross conveyor  30   r . The middle cross conveyor is controlled to receive the packages and to laterally move the packages in either direction towards and onto the respective cross conveyor (e.g.  30   l  or  30   r ). The lateral cross conveyors are controlled to receive a corresponding package and to move the upstream end thereof into and through the respective pinch station  360  and further into the respective open vacuum chamber  353 ′ as described above. The pinch station  360  perforates the respective package and the package is evacuated while the perforated upstream end of the package is positioned inside the vacuum chamber  353 ′, the film extending into the vacuum chamber  353 ′ through the opening. After gas extraction, the respective vacuum chamber  353 ′ is opened and the packages  24 ′ are moved further along paths  30   a - l  and  30   a - r , respectively, and back towards the middle cross conveyor  30   m  and outfeed belt  30   o  in order to be placed in an outlet region of the packaging apparatus  1 ′. 
     Pinch station  360  can include pinch rollers having protrusions  360 ′, on a peripheral surface of a roller, configured to, in combination with recesses  360 ″ present on a counter surface, perforate a film  21  being supplied to the pinch station  360 . As shown, pinch station  360  can be implemented as a set of oppositely arranged rollers carrying, for example, protrusions  360 ′ and recesses  360 ″ (alternatively also any combination of protrusions and/or recesses configured to create one or more apertures; see also above). It is noted that other means for perforating the film  21  can be employed (e.g. heat wires as mentioned above or knife rollers configured to cut along an upstream edge of the package) as long as it is ensured that a seal established by film  21  at the upstream end of the package  24 ′ has been compromised in order to facilitate gas extraction as described in detail above. 
     In some embodiments, several subsequently processed packages are directed into the vacuum chambers  353 ′ in an alternating fashion such that each vacuum chamber  353 ′ receives, for example, every second package in a series of packages (alternatively, any number of subsequent packages  24 ′—e.g. 3—can be directed to one of the vacuum chambers  353 ′ for evacuation). Each vacuum chamber  353 ′ can be sized and configured to be able to process several packages simultaneously, for example between 2 and 5 packages, preferably at least 3 packages as shown in  FIG. 12 . The evacuation station of packaging apparatus  1 ′ has a modular structure, thereby allowing for two or more vacuum chambers  353 ′ to be used simultaneously. This modular design can prevent or alleviate a bottle-neck situation, in which the packaging apparatus  1 ′ can operate only at the speed of the slowest station thereof. 
     The packaging apparatus  1  can comprise an HFFS machine. The HFFS machine may comprise a conveyor belt  30  for supporting and transporting the packages  22 , in a horizontal direction. The product  20  may be disposed on a surface. The surface may extend substantially in the horizontal direction. The surface may comprise the upper surface of a conveyor belt  30 . The conveyor belt  30  may be a continuous conveyor belt  30 . For example, the conveyor belt  30  may be suspended between at least two rollers. The conveyor belt  30  may transport the product  20  in a horizontal direction. 
     The product  20  can be disposed in a tray. The tray supports the product  20 . The tray can comprise walls that extend substantially vertically from the base of the tray to a height greater than the vertical dimension of the product  20 . Alternatively, the tray height may be less than or equal to the height of the product  20 . The packaging extends around the tray. The tray can comprise a material selected from a list consisting of polystyrene, Aluminium, or other thermoplastic material such as PET, or cardboard. The tray can be rigid, solid or foamed, and have any color and shape. 
     The packaging can comprise a multi-layer film  21 . The film  21  can comprise a polyolefin. The film  21  can be a fully coextruded shrinkable film  21 . The package provides a barrier to gas passing between the interior of the package to the exterior of the package. Accordingly, the environment inside the package is isolated from the environment outside the package. This helps to preserve food products  20  and avoid contamination. This can be advantageous with respect to food hygiene. The package can provide a barrier to aromas or to gasses. This can be particularly useful when the product  20  is a food product  20 . The package can be abuse-resistant. 
     The packaging can be transparent or translucent. This allows a customer to see the product  20  through the packaging. For example, the packaging may comprise a transparent film  21 . The packaging film can have anti-fog properties. This ensures high consumer appeal. The packaging film can be printable. This allows labels to be printed directly onto the packaging. 
     The packaging may be formed from a roll of film  21 . The tubular film  21  can be formed by forming a tube from the roll of film  21 . The packaging apparatus  1  can comprise a former configured to form the roll of film  21  into a tube. The former can form the tube by forming a longitudinal seal along the longitudinal edges of the roll of film  21 . The tube may be formed from two webs of film  21 . In this case, the former forms two longitudinal seals along the opposing edges of the two rolls of film  21 . 
     The packaging apparatus  1  can comprise a flusher  34 . The flusher  34  is configured to flush gas through the tube of film  21  that forms the packaging. The gas flush prevents the tube from collapsing. The gas flush helps to maintain a distance between a product  20  in a tray and the film  21 . This helps to improve the hygienic appearance of the film  21  because the film  21  remains untarnished by the product  20 . The flusher  34  flushes gas longitudinally through the tube. The gas used for flushing can comprise about 70% oxygen and about 30% carbon dioxide or other suitably modified atmosphere. 
     Additionally, the flush gas allows the product  20  to be packaged in a modified atmosphere. The gas may help to preserve the product  20 , prolonging its shelf life. The desired amount of gas inside each sealed package depends on the type of product  20  and the length of shelf life needed. 
     The packaging apparatus  1  can comprise a shrinking machine configured to shrink the film  21 . The shrinking machine may be a water- or air-based shrink tunnel, for example a hot air tunnel  33 . The sealed package  24  is shrunk in the shrinking machine. The shrinking process may involve heating the sealed package. The package  24  may be heated to a temperature within the range of from about 130° C. to about 150° C. 
     Before the sealed package  24  is shrunk, there may be undesirable gas trapped in the sealed package along with the product  20 . Additionally, the sealed package  24  may comprise undesirable “dog ears”, where a dog ear is a portion of the packaging that extends away from the product  20  (for example due to the product  20  not being a regular rectangular prism). After the shrinking process the dog ears and the gas content are reduced. This gives the sealed package  24  a more aesthetic appearance. In the case of cheese, the cheese may consume any residual gas that remains in the sealed package  24  following the shrinking step. 
     The product  20  can be a food product  20 . For example, the product  20  may comprise meat, cheese, pizza, ready meals, poultry and fish. The product  20  may be substantially dry, as in the case of cheese. For some products, such as cheese, there is no need for a tray to support the cheese. Alternatively, the product  20  may be wet. In this case, it is particularly desirable for the product  20  to be disposed in a tray. 
     The packaging process of the invention may be employed to package food products  20  that are to have a shelf life in the region of from about six days to about 14 days, for example. 
     Desirably, the packaging apparatus  1  comprises a horizontal form fill and seal machine. However, the packaging apparatus  1  may comprise other types of form fill and seal machines, such as a vertical form fill and seal (VFFS) machine. In a vertical form fill and seal machine, the packages  22  move through the packaging apparatus  1  in a vertical direction during the packaging process. 
     In a VFFS machine, the packaging may be sealed once to form the lower end of a sealed package. The product  20  is then fed into the open-ended package. The top end of the package  22  is then sealed to form a sealed package  24 ′. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the appended claims.