Abstract:
A method of aseptically filling an internally sterilized sealed container having a transfer port which comprises a tubular body which is sealed to the wall of the container and defines a flow passage therethrough, and a sealing plug engaged into the passage, the tubular body having an annular outer sealing face thereon which surrounds the flow passage, including the steps of: supporting the tubular body of the container in a selected orientation and position; providing a sterilization and filling head having at least an outer sealing ring thereon which is adapted to engage and seal with the annular sealing face, and a sterilization chamber located inwards of and at least partially defined by the outer sealing ring; bringing the sterilization and filling head and the tubular body into engagement with each other so that the outer sealing face; introducing a sterilization fluid into the sterilization chamber to sterilize at least the radially outer part of the plug and that part of the tubular body within the outer sealing ring; withdrawing the plug out of the tubular body in a direction away from the container whilst maintaining the sealing ring in sealed contact with the sealing face; introducing a flowable material into the container through the tubular body; reinserting the plug into the tubular body to thereby close the tubular body; and disengaging the sterilization and filling head and the tubular body from each other.

Description:
FIELD OF THE INVENTION 
   This invention relates to a method of aseptically filling containers, apparatus for the aseptic filling of containers, to containers incorporating an inlet assembly with which the method may be used, and to a plug and gland port for such containers. 
   BACKGROUND OF THE INVENTION 
   The filling of pre-sterilized containers in an aseptic manner is known and various systems are employed which utilize different filling apparatus, different containers, and different sterilization techniques. Specifically, the container to be filled is produced in a manner which ensures that the interior of the container is sterilized during manufacture. During the filling procedure an inlet into the container is opened and a filling nozzle used to fill the container with a selected flowable material. The inlet is then sealed to thereby contain the flowable material within the container until dispensing is required. To ensure that the contents of the container is kept as free of contaminating bacteria and other micro organisms as possible it is essential that the act of filling the container does not in itself introduce contaminants into the interior of the container. Also, the resealing of the container after it is filled must be done in such a way that a proper seal is achieved so that contamination does not take place during transportation or storage. 
   Various prior art patents have addressed the aforementioned problems and reference may be made to U.S. Pat. No. 4,805,378 (Anderson), U.S. Pat. No. 2,930,170 (Holsman et al), U.S. Pat. No. 4,542,530 (Thomas et al) and U.S. Pat. No. 4,672,688 (Kalkipsakis). These prior art patents describe systems which are successful to a greater or lesser extent. However, the prior art systems do suffer from certain deficiencies, at least under some filling circumstances. 
   For example, U.S. Pat. No. 4,805,378 discloses an arrangement in which a flap is positioned across the mouth of the filling inlet, which provides some measure of obstruction to the flowable material entering the container. Current food processing plants can produce product at a rate of in excess of 20,000 liters per hour and it is important that the container is able to receive a product at this flow rate in order to avoid providing multiple head filling systems and the like. To achieve filling rates of this order relatively large diameter filling inlets are required into the containers and the flap system disclosed in U.S. Pat. No. 4,805,378, limits the diameter and flow rate into the container. Also, for highly viscous materials, and for materials which contain solid particles, the flap system is not always completely suitable. 
   The U.S. Pat. No. 4,805,378 discloses a container which is filled via an upstanding plastics collar, at one end of which a first flange is heat fused to the flexible plastic sheet wall of the container surrounding a filling opening in the container and, at a second flange at the opposite end of the collar, a rupturable sheet plastics membrane is also heat fused. The sheet plastics membrane, which is heat sterilized in manufacture but which most likely would be recontaminated externally before filling, is resterilized immediately prior to filling by a fluid (for example pressurized steam) after being brought into engagement with a filling head of an aseptic filler. In the described method, an incision tool forming part of the filling head, sterilized along with the exterior of the membrane, is advanced to cut the membrane then withdrawn to enable admission of the liquid to be packaged through the collar and through gaps formed between the flap partially heat fused to the flange inside the container. 
   As discussed in U.S. Pat. No. 4,805,378, the cutting of the resterilized membrane involves making a pair of straight incisions, crossed at right angles passing through the center of the membrane and extending radially outward to a point just inside the outer flange of the upstanding plastics collar. Accordingly, as the liquid or liquid-like product flows into the bag to fill it, the four cut tips or “reversed petals” of the membrane turn inwardly with the flow and extend towards the inner and end of the collar where it is connected to the bag in the region that is subsequently sealed closed as described. There are occasionally experienced instances of unreliability with this arrangement in that the four petals of the top membrane, since they remain on the filled sealed package, are difficult to clean underneath to remove remnants of the packaged product inside of the collar during the flushing cycle. Also, the petals tend to reduce the flow rate of the product into the container during filling which can be disadvantageous from a production point of view with viscous or particulate containing products. 
   There is furthermore a risk that the tips of the petals might wrap underneath the inside corner of the flange and be caught up in the subsequent final heat sealing operation. If this were to happen there would be a potential for a leakage path to bypass the seal or, at least, a potential source of failure of the seal. Accordingly, the axial height of the collar should be sufficient in relation to the diameter opening to prevent this possibility. In use commercially, the diameter of opening as disclosed in the Anderson patent is known to be in the range of 16–32 mm. With the desired future extension of the size of opening up to 60 mm or 70 mm, using the arrangement disclosed in the patent would require a corresponding increase in axial height of the collar. There would be no other need to increase the height of the collar other than to ensure that the cut petals of the membrane could not enter the sealing region, but such a high profile of collar would be unacceptable in general to fillers and end users of the package alike. It is therefore an object of this invention to provide a method which will overcome the disadvantages associated with a rupturable outer membrane. 
   Typically, the aforementioned packaging systems are used with high acid products, predominantly tomato paste, orange juice and juice concentrates. It is also known to use this type of packaging system with low acid products, such as milk, cream and egg pulp for example. 
   Manufacturers are beginning to take advantage of processing system developments and market acceptance, for an increased range of particulate and concentrate products. The types of products currently being considered for packaging are pineapple chunks, diced tomatoes, ready prepared meals, meat sauces, fruit particulate, and various other similar type products. These products come in a range of different acidities and larger diameter filling nozzles are generally required in order to fill containers at the required flow rate and accommodate larger particulate sizes. 
   Containers having capacity of 1,000 liters or more are typically used for bulk packaging and with increased capacity of processing plants there is currently a need for a high capacity, highly aseptic packaging system that utilizes a large diameter filling nozzle and provides a high quality seal after filling and which can be used with low acid products. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a method of aseptically filling an internally sterilized container having a transfer port which comprises a tubular body which is sealed to the wall of the container and defines a flow passage therethrough, and a sealing plug engaged into the passage, the tubular body having an annular outer sealing face thereon which surrounds the flow passage, the method comprising the steps of:
         supporting the tubular body of the container in a selected orientation and position;   providing a sterilization and filling head having at least an outer sealing ring thereon which is adapted to engage and seal with the annular sealing face, and a sterilization chamber located within the outer sealing ring;   bringing the sterilization and filling head and the tubular body into engagement with each other so that the outer sealing ring engages and seals with the annular sealing face;   introducing a sterilization fluid into the sterilization chamber to sterilize at least the radially outer part of the plug and that part of the tubular body within the sealing ring;   withdrawing the plug out of the tubular body in a direction away from the container whilst maintaining the sealing ring in sealed contact with the sealing face;   introducing a flowable material into the container through the tubular body;   reinserting the plug into the tubular body to thereby close the tubular body; and   disengaging the sterilization and filling head and the tubular body from each other.       

   The method may include the further steps of:
         providing the sterilization and filling head with an inner sealing ring which is co-axial with the outer sealing ring, the sterilization chamber being formed in the annular space between the two sealing rings;   providing a plug with an annular sealing face thereon which is co-axial with the annular sealing face on the tubular body and is adapted to be engaged by the inner sealing ring;   bringing the sterilization and filling head and the tubular body into engagement with each other so that the outer sealing ring engages and seals with the annular sealing face on the body, and the inner sealing ring engages and seals with the annular sealing face on the plug; and   introducing the sterilization fluid into the annular sterilization chamber.       

   The method may further include the steps of:
         providing a gripping jaw on the sterilization and filling head within the outer sealing ring; and   gripping the plug with the gripping jaw in order to withdraw the plug from the tubular body.       

   The method may include the further steps of:
         maintaining the outer sealing ring in sealing engagement with the annular sealing face on the body, and the inner sealing ring in sealing engagement with the sealing face on the plug;   gripping the plug with the gripping jaw; and   extracting the plug from the tubular body whilst maintaining the inner sealing ring in sealing engagement with the sealing face on the plug.       

   The method may include the further steps of:
         partially inserting the plug into the tubular body;   cleaning the peripheral outer surfaces of the plug prior to fully inserting the plug into the tubular body; and   fully inserting the plug into the tubular body.       

   The step of cleaning the peripheral outer surfaces of the plug may be achieved by introducing a sterilization fluid into the sterilization chamber with the plug partially inserted into the flow passage in the tubular body. 
   The method may include the steps of sealing the plug to the tubular body during or after the plug has been reinserted into the tubular body. The sealing may be achieved by welding the plug in to the tubular body. The welding may be done using high temperature sterilization fluid, preferably steam. 
   According to a second aspect of the invention there is provided a sterilization and filling apparatus for aseptic filling of sterile containers having a filling nozzle comprising a tubular body with a flow passage therethrough and a plug for closing the flow passage, at least the tubular body having an annular sealing face thereon, the apparatus comprising:
         holding means for holding the container and/or the tubular body in a selected position;   a sterilization and filling head having at least an outer annular sealing ring adapted to engage the annular sealing face on the tubular body, the sterilization and filling head having a sterilization chamber located inwards of the outer sealing ring, the sterilization and filling head having a cavity therein adapted to receive the plug of a container to be filled, the sterilization and filling head and/or the tubular body being movable towards and away from the other;   sterilization fluid supply means adapted to supply sterilization fluid to the sterilization chamber;   a plug extractor adapted to extract a plug from the tubular body and move the plug into the cavity in the sterilization and filling head; and   filling means adapted to fill the container through the sterilization and filling head when the plug has been extracted.       

   Preferably the sterilization and filling head includes an inner sealing ring which is co-axial with said outer sealing ring and spaced inwardly therefrom to define an annular space therebetween, said annular space forming said sterilization chamber, said inner sealing ring being engageable with a sealing face provided on the plug. 
   The plug extractor may comprise one or more gripping jaws adapted to grip the plug and extract it from the tubular body into the cavity. The jaws may be mounted to a ram, which is moveable in an axial direction towards and away from the plug, the jaws being moveable between gripping and release positions. 
   Preferably the jaws automatically move to a gripping position when the ram moves in direction away from the plug, and move into the release position when the ram moves towards the plug. The ram may be adapted to drive the plug into the tubular passage after the container has been filled. 
   The sterilization and filling head may be adapted to shut off the flow of filling material into the container prior to the plug being fully inserted into the tubular passage. The sterilization and filling head may, furthermore, be adapted to clean the plug with sterilization fluid when the plug is partially re-inserted back into the tubular passage. 
   A further aspect of the invention provides an aseptic container adapted to be filled with a flowable material, the aseptic container having a filling opening comprising a tubular body having a flow passage therethrough, and a plug for sealing the flow passage, the plug having gripping formations on the outer face thereof, and retaining means or formations thereon for cooperatively or cooperatively locking the plug into the flow passage. 
   Preferably said gripping formations will allow the application of an axially directed force to be applied to the plug to remove or re-install the plug into the filling opening. Alternatively the gripping formations will allow the applications of a rotational force to be applied to the plug to remove or re-install the plug into the filling opening. 
   Preferably the plug is removed and reinstalled into said opening by axial means, preferably of a slide or interference fit. Alternatively the plug and opening may include a screw thread or cam or bayonet locking means. 
   Optionally the plug may be cup shaped having an end wall and a cylindrical skirt depending from the end wall, the end wall adapted to be outermost when the plug is inserted into the flow passage. The gripping formations may be formed on the end wall and project in a direction which is opposite to that in which the skirt extends from the end wall. The gripping formations may take the form of a head which stands proud of the end wall. The head may be undercut to provide purchase for the gripping jaw which is adapted to extract the plug from the flow passage. The locking formations may comprise a radially outwardly projecting annular rib formed on the plug, said rib being adapted to locate behind a shoulder, end face or within a groove formed in or adjacent the flow passage. The flow passage and/or the plug may have an annular seal therein adapted to seal with a plug inserted into the annular passage. 
   The plug and/or the tubular body may both be formed of a thermoplastic material adapted to bond together under temperatures of between about 130° C. and 180° C. 
   The plug and the tubular body may be sealed together during manufacture. That seal may be mechanically rupturable, or it may be adapted to be weakened under temperatures of between about 130° C. and 180° C. thereby providing an arrangement for simplified extraction of the plug after it has been sterilized by a high temperature sterilization fluid. 
   According to a further aspect of the invention there is provided a plug and gland port for use on an aseptic container, said port comprising:
         a tubular body having a flow passage therethrough defined by a cylindrical inner wall of the tubular body, and   a plug for sealing the flow passage, the plug having gripping formations on the outer face thereof, and retaining means or formations thereon for locking the plug into the flow passage, said retaining means comprising an annular recess formed around the periphery of the plug, and an annular rib or lip formed around and standing proud of the cylindrical inner wall of the tubular body, the rib or lip being adapted to locate in the recess to form a locating and/or sealing engagement with the recess when the plug is operatively installed within the tubular body.       

   Preferably the annular recess on the plug is at least partially filled with a sealing ring. The sealing ring may be in the form of a low melt sealant deposited in said recess. The low melt sealant may comprise a material such as a polyolefin elastomer. 
   Preferably the rib or lip on the cylindrical inner wall is spaced a first distance away from the operatively outer end face of the tubular body. Preferably the annular recess on the recess on the plug is spaced a second distance away from the operatively outer end face of the plug, said second distance being less than said first distance. 
   The plug may have a second annular recess formed around the periphery thereof, said annular recess being spaced from the first annular recess, the second annular recess being spaced a distance away from the operatively end face of the plug by a distance which is substantially the same as the distance which is substantially the same as the distance which the rib or lip is spaced away from the operatively outer end face of the gland so that when the rib or lip is located within the second annular recess the operatively outer end faces of the gland and the plug are substantially flush with each other. Prior to filling the container the gland and plug may be welded together. 
   The rib or lip may have a generally triangular form in cross section so as to provide a chamfered or severed face in both an outwardly facing direction and an inwardly facing direction to allow for simplified engagement and disengagement of the plug with the gland. 
   These and further features of the invention will be made apparent from the description of preferred embodiments thereof given below by way of examples. In the description reference is made to the accompanying drawings, but the specific feature shown in the drawings should not be construed as limiting on the invention. 
   In this specification and claims, where the words “comprising”, “comprised” or words derived therefrom are used, those terms are to be interpreted inclusively rather than exclusively. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a cross sectional half view through part of a container and the transfer port into the container according to the first embodiment of the invention, the other half view being a mirror image of  FIG. 1 . 
       FIG. 2  shows the cross sectional side view of a sterilization head according to the invention in engagement with the port shown in  FIG. 1 ; 
       FIG. 3  shows a similar view to the of  FIG. 2  with sterilization fluid sterilizing the outer surface of the transfer port; 
       FIG. 4  shows a similar view to that of  FIGS. 2 and 3  with the plug removed from the tubular body of the transfer port and with filling material being introduced to the container; 
       FIG. 5  shows a similar view to that of  FIG. 3  but with the inlet partially closed by the plug partially inserted into the inlet and with sterilization fluid being used to flush and clean the plug; 
       FIG. 6  shows a similar view to that of  FIG. 5  with the plug fully inserted into the tubular body; 
       FIG. 7  shows the sterilization and filling head and the transfer port separated from each other; 
       FIG. 8  shows a cross-sectional side of a second embodiment of sterilization and filling head with the transfer port in engagement with the head; 
       FIG. 9  shows a similar view to that of  FIG. 8  with the plug lifted out of the tubular body; 
       FIG. 10  shows a similar view to that of  FIGS. 8 and 9  with the plug partially closed; 
       FIG. 11  shows a similar view to that of  FIG. 8  but with the plug fully closed; 
       FIGS. 12 to 16  show cross-sectional side views of a third embodiment of sterilization and filling head according to the invention in engagement with a transfer port in different stages of the sterilization and filling operation; 
       FIGS. 17 to 20  show cross-sectional side views of different embodiments of transfer port according to the invention; 
       FIG. 21  shows a cross-sectional side view through a plug and gland port according to the invention prior to filling; 
       FIG. 22  shows an enlargement of the interface between the plug and gland in the position shown in  FIG. 21 ; 
       FIG. 23  shows a cross-sectional side view of the plug and gland port after the container has been filled; and 
       FIG. 24  shows an enlargement of the interface between the plug and gland in the position shown in  FIG. 23 . 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Turning initially to  FIG. 1 , a container  10  is shown having a flexible wall  12  with a transfer port  14  therethrough which is used to introduce a flowable material into the container and through which the material may be, but is not necessarily, dispensed from the container. The transfer port  14  includes a tubular body  16  (also referred to in the art as a nozzle or gland) having a cylindrical inner wall  18  which defines a flow passage  19  through the body. An outwardly directed flange  20  serves as a bonding surface to which the container wall  12  is affixed thereby providing a fluid tight seal between the container wall and the body  16 . A plug is provided for closing the passage  19  through the tubular body  16 , the plug  22  having an end wall  24  and a skirt  26  which is attached to the periphery of the wall  24  and has an outer surface  28  which is a tight friction fit with the inner wall  18  of the body. The wall  24  has an upstanding head  30  which is undercut as indicated at numeral  32  to define a gripping region for the extraction of the plug out of the body  16 . The outer face  34  of the tubular body is generally perpendicular to the axis  36  of the tubular body and defines a sealing face with which a sterilization and filling head  39  will engage, as described in more detail herebelow. The outer face  38  of the plug is similarly perpendicular to the axis  36  and also defines a sealing face with which the sterilization and filling head will engage. 
   Turning to  FIG. 2  of the drawings, a sterilization and filling head  39  is shown comprising an outer sealing ring  40 , an inner sealing ring  42  between which is formed a sterilization chamber  44 . The outer sealing ring  40  has a downwardly extending flange  46  which locates around the outer periphery of the tubular body  16 , and the sealing ring  40  includes a sharp edged blade  48  which is adapted to engage with and bite into the sealing face  34  on the body  16 . The inner sealing ring  42  similarly has an annular blade  50 , which is adapted to bite into and seal with the sealing face  38  on the plug  22 . 
   In order to commence the filling operation the sterilization and filling head  39  and the upper surface of the transfer port  14  are brought into engagement with each other, as shown in  FIG. 2 . This is most conveniently done by gripping the transfer port with gripping jaws (not shown) and lifting the transfer port in the direction of axis  52  until the sealing faces  34  and  38  engage and seal with the sealing rings  40  and  42  respectively. 
   The sterilization and filling head is provided with a sterilization fluid supply line  54  which leads into the sterilization chamber  44  and which is controlled by an inlet valve  56 . A sterilization fluid discharge line  58  leads from the sterilization chamber  44  and is controlled by an exit valve  60 . The sterilization fluid will generally comprise steam supplied under pressure at a temperature of between 130° C. and 180° C. 
   The inner sealing ring  42  is formed on the end of a sliding sleeve  64 , which is slideable along axis  52  towards and away from the transfer port  14 . The sliding sleeve  64  serves as a control valve for controlling the flow of a flowable product into the container, as is described in more detail below. 
   An axially moveable plunger or ram  62  is moveable along axis  52  within a cylindrical cavity  66  formed within the sleeve  64 . The ram  62  has a series of gripping jaws  70  fitted to the end thereof which are spring loaded by means of a spring  74 . The gripping jaws  70  are adapted to engage with the head  30  of the plug  22  in order to pull the plug  22  out of the tubular passage  19 . 
   The sterilization and filling head  39  is provided with a product supply passage  76  through which product to be filled into the container  10  is fed through the head. When the sleeve is retracted to the position shown in  FIG. 4  product will flow into the container through the passage  76 . 
   In use, the apparatus operates substantially as follows. Firstly, the tubular body  16  is brought into engagement with the outer sealing ring  40  so that the blade edge  48  embeds into the sealing face  34 . The tubular body  16  will be held under pressure against this blade edge  48  for the entire filling process so that a seal will be maintained. Simultaneously the inner blade edge  50  will bed into the sealing face  38  of the plug  22 . At this stage the sterilization cavity  44  will be a sealed cavity. It will be noted that the outer sealing ring  40  and the inner sealing ring  42  are located on opposite side of the interface between the tubular body  16  and the plug  22 . 
   In this position, the sterilization head will be tightly clamped against the transfer port  14 , and the ram  52  will be lifted causing the jaws  70  to clamp tightly around the head  30 , thereby gripping the head  30 . Thereafter, the sterilization chamber  44  will be flushed with a high temperature sterilization fluid, typically steam under pressure, to thereby clean all exposed surfaces within the sterilization chamber of any contaminating micro organisms. It should be noted that since the gap between the inner and outer sterilization rings is small, only a small area of the transfer port needs to be sterilized which allows for relatively high temperature sterilization, and short exposure time. 
   Once sterilization has taken place, and this will generally take between two and five seconds at 150° C., the sleeve  64  will begin moving upwardly and in so doing the plug  22  will be pulled out of the tubular body  16  to the position shown in  FIG. 4  of the drawings. As shown in  FIG. 4 , the plug  22  is suspended in a cavity within the sealing head above the tubular body  16  and the supply passage is opened. 
   The product  78  to be filled into the container will then be supplied through the supply passage  76 , the product  78  passing down the flow passage  19  and into the container. It will be noted that the product  78  comes into contact with the underside of the plug  22  as well as the skirt portion of the plug  22 . However, the product does not come into contact with any surface which has not been rendered bacteria free as a consequence of either sterilization during manufacture of the container or the sterilization operation referred to above. Thus, the product will in no way be contaminated during the filling process. Provided the product itself is bacteria free at the time it is introduced into the container it should receive no bacteria contamination during the filling process and should therefore be bacteria free within the container. 
   Once the container is filled, the plug  22  will be replaced into the tubular body  16 . This process is shown in  FIG. 5  of the drawings. As shown, the plug  22  is pressed into the tubular body so that the skirt  26  enters and engages with the cylindrical surface  18 . At this point, it will be noted, the ports  56  and  60  have again been opened so that steam flushes through the sterilization chamber as the plug is being closed. 
   Described below is an arrangement in which the steam which is used to evacuate the sterilization chamber after closure of a plug may be used to clean substantially the entire outer surface of the plug as the plug is being introduced into the passage  19 . 
   In the embodiment shown in  FIG. 5 , however, the steam will clean and evacuate the sterilization chamber and upper surfaces of the plug and tubular body between the outer and inner sealing rings. 
   Once the transfer port has been cleaned in the manner described and depicted in  FIG. 5 , the plug can be pushed further into the passage  19  as indicated in  FIG. 6  of the drawings. It will be noted that the inner wall  18  of the tubular body has an annular groove  82  which lies just below the sealing surface  34 . The plug has an outwardly directed lip  84  on its outer edge and when the plug is pressed into the passage  19  so that the surface  38  lies below the surface  34  the lip  84  will locate in the groove  82  to provide a locking arrangement between the plug and the tubular body. Optionally the groove  82  may have an annular elastomeric seal  86  located therein and the lip  84  will engage with that seal  86  to form a bacteria proof sealing arrangement. 
   It will be noted that as the ram  52  moves the plug inwardly from the position shown in  FIG. 5  to the position shown in  FIG. 6  the jaws  70  will automatically disengage from the head  30  to allow the plug  22  to be pressed further into tubular body  16 . 
   It will be noted that towards the lower end of the sleeve  64  a tapered or bevelled sealing surface  88  is formed. This sealing surface  88  is adapted to engage and seal with a seat  90  which is defined within the sterilization and sealing head just above the sterilization chamber. When the sleeve  64  moves to a closed position, as shown in  FIG. 5 , the surface  88  will engage and seal with the seat  90  to form a fluid tight seal. It is envisaged that this seal will be metal to metal seal or some other form of hard seal which will form a positive stop for the downward movement of the sleeve  64 . This will allow the sleeve  64  to be moved up and down using pneumatics. 
   The hard seal will serve to sever or shear any particulate materials that might otherwise be trapped as the sleeve  64  moves to the closed position. 
   Clearly there may be many forms of interlocking arrangements which may be provided between the plug and the tubular body. What is important is that no micro passageway exists for the passing of microorganisms between the plug and the tubular body which could otherwise compromise the integrity of the seal provided between the plug and the tubular body. 
   Alternative arrangements for sealing the plug in the tubular body include some form of welding system. For example, either the plug or the tubular body, or both, may be formed of a material which will soften in the presence of the high temperature sterilization fluid and, when so softened, weld the plug and the tubular body together as the plug is fully inserted into the tubular body to thereby form a seal between these two components which is bacteria proof. It will also be possible to provide a third component which will melt in the presence of the high temperature steam and form a bacteria proof seal between the plug and the tubular body. Some form of hot melt adhesive, for example, coated onto the outer surface of the skirt  26  could achieve the desired welding type seal arrangement. These aspects are discussed in more detail below. 
   Turning now to  FIGS. 8 to 11  of the drawings, a second embodiment to the invention is shown which is similar to that of the first embodiment except for a difference in the manner in which the sleeve  64  serves to close off the flow of product through the supply passage  76 . In this description parts which are similar to or the same as those referred to in the previous embodiment have been given the same numbers. These parts will not be described again. 
   As shown, the sleeve  64  has a sealing surface  88  on the lower end thereof which is adapted to seal with a correspondingly tapered seat  90  on the sealing head. However, seat  90  has been spaced some distance lower than that of the previous embodiment. The sterilization and filling head in this embodiment is provided with an additional sliding seal  92  which is adapted to seal with the outer surface  94  of the sleeve  64  as the sleeve  64  moves down towards its closed position. Thus, as the sleeve moves downwardly from the open position shown in  FIG. 9  to the partially closed position shown in  FIG. 10 , the outer surface  94  of the sleeve  64  will engage the sliding seal  92  to close off the flow of product prior to the tapered sealing surface  88  contacting the seat  90 . This has the advantage that steam under pressure, as shown in  FIG. 10 , can be introduced into the sterilization chamber  44  prior to the plug  22  being fully inserted into the tubular body  16 . As shown clearly in  FIG. 10 , the skirt  26  of the plug  22  is exposed in the partially closed position shown in  FIG. 10  so that the other surface  28  of the skirt can be cleaned by sterilization fluid, generally steam. It is envisaged that in a partially closed position shown in  FIG. 10  steam will be introduced into the sterilization chamber  44  to clean substantially all product off the outer surface  28  of the plug  22 . Thus, when the plug is fully inserted into the tubular body  16  as shown in  FIG. 11 , the surface  28  will have been cleaned and therefore micro passages which might otherwise have remained as a consequence of a product being trapped between the surfaces  28  and  18  will to a substantial extent be eliminated. 
   A further advantage of clearing the surface  28  of the plug  22  with high pressure, high temperature steam is that where it is desired to weld the plug  22  into the tubular body  16  the steam will serve to soften the outer surface of the plug. These two components will then weld together when the plug is in its closed position. 
   Turning now to  FIG. 12 ,  FIG. 13 ,  FIG. 14 ,  FIG. 15  and  FIG. 16  of the drawings, a sterilization and filling head similar to the previous embodiment is shown which is also used to close off the flow of product into the container prior to the plug being fully closed. 
   In this embodiment, the sterilization and filling head  98  has a moveable sleeve  100  which is used to lift the plug  22  out of the tubular body  16  and also serves to open and close the filling passage  76 . The sleeve  100  is formed of an inner sleeve  102  and outer sleeve  104  which are moveable relative to each other. The inner sleeve  102  has a sharp lower edge  106  which is adapted to engage the sealing surface  38  on the plug  22 . The outer sleeve  104  has a bevelled lower edge  108  which is arranged to engage and seal with the seat  90  of the sterilization and filling head. A sliding seal  110  seals the gap  112  between the inner sleeve  102  and outer sleeve  104 . 
   Illustrated in  FIG. 12 , the ram  62  is shown in an extended position relative to the gripping jaws  70 . This keeps tips  71  of the gripping jaws  70 , which engage the undercut  32  of plug  22 , in an unengaged position whereby the tips  71  are clear of the undercut  32 . 
   As illustrated in  FIG. 13 , as the ram  62  is retracted, a flange  73  on its lower end engages an internal shoulder  75  on the jaws  70 . This moves the jaws  70  axially away from the tubular body  16  which forces ramps  77  on each of the jaws  70  to engage ramps  79  on the inner sleeve  102 . This forces the tips  71  to engage the plug beneath the undercut  32 . 
   In the condition illustrated in  FIG. 13  sterilization fluid enters the sterilization chamber  44  as in the embodiment of  FIGS. 2 to 7  or  8  to  11 . 
   Once sterilization of the portions of the plug  22  and tubular body  16  which are exposed in sterilization chamber  44  has been completed, the inner sleeve  102 , ram  62  and plug  22  are retracted together until the outer surface  38  of plug  22  engages the extremity of ramps  79  as seen if  FIG. 14 . With each of items  104 ,  102 ,  62  and  22  maintaining their positions relative to each other, the sleeve  104 , sleeve  102 , ram  62  and plug  22  are retracted in unison to the positions as illustrated in  FIG. 15 . This is the most preferred method of retraction as it minimizes the amount of outer surface  38  of plug  22  which will be exposed to the product  78  flowing thereover. This will thus decrease the possibility of contamination. 
   A less preferred retraction scheme is to allow the sleeve  104 , sleeve  102 , ram  62  and plug  22  to retract in unison in the positions as illustrated in  FIG. 13 . Then once the sleeve  104  has retracted to its fullest extent this will leave the plug  22  somewhat occluding the passage of the product  78 . So as to minimize the occlusion, the sleeve  102 , ram  62  and plug  22  can be moved in unison relative to the sleeve  104  until the outer surface  38  of plug  22  engages the ramp  79  as illustrated in  FIG. 15 . Clearly, this has a greater probability of contaminant or food product being trapped between sleeves  102  and  104 , but this contaminant will be cleared once flushing occurs just after the plug  22  is placed back in the gland  16 . 
   If desired the circumference of the plug  22  can be decreased or the internal diameter of the sleeve  104  increased so that the plug  22  can move into the sleeve  104  and thus produce a circumferential seal around the plug  22 . This will ensure that no part of the surface  38  will be able to hold particulate. To do this an interference fit between the plug  22  and sleeve  104  is preferred but not to a degree which will make the removal of the plug  22  from the sleeve  104  difficult. 
   Once the outer sleeve  104  has retracted to fully open the passage  76 , as illustrated in  FIG. 14 , the inner sleeve and plug  22  are potentially occluding the passage  76 . If the opening is not sufficient, the inner sleeve  102  and ram  62  move together until such time as the upper surface of the plug  22  engages the bevelled lower edge lower edge of the outer sleeve  104 , as is illustrated in  FIG. 15 . If desired, this step of having the upper surface of plug  22  engaging the bevelled lower edge of the outer sleeve  104  can be done prior to the outer sleeve  104  disengaging from the tapered seat  90 . 
   Once filling has been completed, the outer sleeve  104 , inner sleeve  102  and ram  62  are moved together axially towards the tubular body  16 . 
   As illustrated in  FIG. 16 , once the outer sleeves  104  closes passage  76  by engaging tapered seat  90 , the inner sleeve and ram have stopped simultaneously therewith. 
   At this point, as illustrated in  FIG. 16  the valve  56  is opened so as to introduce sterilizing fluid into the sterilizing chamber  44 . 
   The sterilizing fluid will sterilize and flush any food product which remains in the sterilizing chamber  44  to thereby clean the side surfaces of the plug  22  prior to closing. 
   The exposure to the side surfaces of the plug  22  to the temperature of the sterilizing fluid will soften them thereby helping to create a seal when the plug  22  is pushed into the tubular body  16 , as has been described with respect to the embodiment of  FIGS. 2 to 7  or  8  to  11 . 
   Clearly, by providing a facility whereby the inner sleeve  102  may be moved relative to the outer sleeve  104  the plug  22  can be moved to a partially open position, or a fully open position, when the outer sleeve is still in engagement with the seat  90 , thereby closing off the filling passage  76 . 
   Likewise, during the closing of the filling passage  76 , the outer sleeve  104  can be first moved into a closed position against the seat  90  whilst the plug is in an open, or partially open condition. This will allow the outer surface of the plug  22  to be cleaned with sterilization fluid in a manner described above with reference to the previous embodiment. Clearly the ability to close the filling passage  76  using the outer sleeve  104  whilst being able to independently manipulate the plug  22  may be advantageous in certain circumstances. 
   Turn now to  FIG. 17 ,  FIG. 18 ,  FIG. 19  and  FIG. 20  of the drawings. Various different types of transfer port arrangement are shown in these figures. Clearly these are not the only kinds of transfer ports which might be used but these four embodiments do show the types of ports which might be considered for different applications. 
   Turning first to  FIG. 17 , it will be noted that the plug  22  and transfer port  16  have a seal  114  therebetween which will seal off the gap  116  between the plug  22  and transfer port  16 . The seal  114  will, it is envisaged, be adapted to melt, or at least soften when heated by the sterilization fluid. Thus, when sterilization of the transfer port  16  is taking place prior to the plug  22  being removed from the tubular body  16 , the seal  114  being exposed to hot sterilization fluid, will melt, and the plug  16  may thereafter be extracted from the tubular body  16 . The seal  114  will, however, have ensured that no contaminating microorganisms could have entered into the gap  116  between the plug  22  and tubular body  16 . 
   A different seal arrangement is shown in the right hand side of the  FIG. 18  embodiment. In this arrangement an outer surface  119  of the plug  22  has an adhesive material  118  coated on the thereon which is adapted to bond to the inner surface  120  of the tubular body  16 . Thus, when the outer surface  119  of the plug  22  is heated during the closure operation, as described above with references to the second and third embodiments of the invention, this adhesive material  118  will soften so that when the plug  22  is closed, as shown in the  FIG. 18  drawing, adhesive  118  will bond to the surface  120 . This will form a permanent bond between the plug  22  and tubular body  16  thereby ensuring that the seal between two components will not be compromised after the container has been filled. 
   The embodiment shown in  FIG. 19  is similar to that shown in  FIG. 1 . The seal is achieved by an elastomeric seal  122  which is located in a groove  124  formed in the inner wall of the tubular body  16 . The elastomeric seal  122  may be adapted to bond with the outer wall of the plug  22 , particularly where the plug  22  has been heated during the closing operation. The plug  22  also has a pair of outwardly directed ribs  126  which are located in corresponding grooves  128  formed in the inner wall of the tubular body  16 . 
   In the embodiment shown in  FIG. 20 , the plug  22  has a relatively deep skirt  130  having an outwardly directed flange  132  on the lower edge thereof and an outwardly directed flange  134  on the upper edge thereof which locates in a recess  136  formed in the tubular body  16 . Provided the plug  22  is a tight sliding fit within the tubular body  16 , the combined effect of the flange  132  and  134 , and the lengthy face to face contact between the plug  22  and the tubular body  16  should ensure that the seal between the plug  22  and the tubular body  16  is not compromised. Also, the outwardly directed flange  132  will have a wiping effect as the plug  22  is inserted into the tubular body  16  to ensure that the inner surface of the tubular body  16  is relatively free of product when the plug  22  is inserted into the tubular body  16 . The outer surface of the plug  22  may also be cleaned during the insertion process to ensure that both surfaces are substantially free of product when the plug  22  is fully inserted into the tubular body  16 . 
   The upstanding head  30  of the plug  22  of  FIG. 20  does not include an undercut  32  as do the other embodiments previously described. In  FIG. 20 , the head  30  is engaged by a claw  70 A having a sharp projection  70 B at its terminus. The projection  70 B will be forced into the material of the head  30  when the jaws  70 A are moved axially away from the tubular body  16  causing the ramp  77 A to engage ramp  79 A thus forcing the projection  70 B in the direction of the head  30 . 
   In the above described embodiment when sealing of the plug  22  within the gland  16  after the container has been filled, it is best to ensure than contaminants do not enter the container along a pathway defined at the interface between the gland  16  and the plug  22 . However, it is also important that the plug  22  is relatively easily removable from the gland  16  for filling purposes. Also, after the container has been filled, it is important that the plug  22  is relatively easily insertable into the gland  16  and, once inserted, is relatively easily removable from the gland  16  in order to decant the contents of the container through the gland  16 . 
   Whilst it is possible to form both the plug  22  and the gland  16  to relatively close tolerances, it is unsafe to rely only on those close tolerances to ensure that the integrity of the seal between the plug  22  and the gland  16  is maintained. Also, if the fit between the plug  22  and the gland  16  is made too tight then insertion of the plug  22  into the gland  16 , and the subsequent removal of the plug  22  from the gland  16 , are made that much more difficult and can lead to failure of the system either on closing or on opening which, in turn, can lead to loss of contents of the container. 
   Typically the container and gland  16  will be sterilized internally after manufacture, generally by ionizing radiation. It is essential in a practical sense that the interior of the container is maintained in a sterile condition prior to being filling so that material introduced into the container is introduced into a sterile environment. To aid in this maintenance of sterility the embodiments of  FIGS. 21 to 24  will be of assistance. 
   As shown in  FIG. 21 and 22 , a plug and gland port includes a gland  16  and a plug  22 . The gland  16  is comprised of a tubular body which defines a passage  14  therethrough and has an inner cylindrical wall  18 . The gland  16  is fitted to a wall of a container and fluid material is introduced through the passage  14 . The gland  16  has an outer end face  34  and an outwardly directed rib  120  extends around the periphery of the gland. The rib  120  serves to strengthen the gland and ensure that it does not deform during the filling process or when the plug  22  is inserted into or removed from the gland  16 . 
   The plug  22  includes an end wall  24  and a skirt  26 , the outer surface of this skirt  26  being a close sliding fit with the cylindrical wall  18 . The plug has an upstanding head  30  which is undercut as shown at numeral  32  so that the plug can be gripped and removed from the gland  16  or reinserted into the gland  16  as required. 
   The radially outer surface of the skirt  26  has a first annular recess  122  formed therein which is filled with an elastomeric sealing ring  124 . The sealing ring  124  is preferably formed of a low melt point sealant such as polyolefin elastomer. 
   The plug  22  and the gland  16  need not be formed of the same material. The gland may, for example, be formed of polyethylene and the plug may be formed of a material such as polypropylene. 
   The skirt  26  has a second annular recess  126  formed therein located on the radially outer surface of the skirt near the innermost end thereof. 
   The wall  18  of the gland  16  has an annular rib or lip  128  formed therein which is best seen in  FIG. 2  of the drawings. It will be noted that the rib  128  has a generally triangular form in cross section so that the outwardly facing surface  130  and the inwardly facing surface  132  both have a tapered or bevelled configuration to facilitate the engagement of the rib  128  in the groove  126 . It will be noted that the end  134  of the skirt  26  is also of tapered or bevelled configuration to facilitate the insertion of the skirt into the gland. 
   In the position shown in  FIGS. 21 and 22  the end face  38  of the plug  22  is flush with the outer end face  34  of the gland  16 . This will be the condition prior to the container  12  being filled with material. 
   If necessary, the plug and the gland may be sealed together, prior to filling, by providing a temporary weld or seal as shown at detail  136  in  FIG. 22 . As is known in the art, the interior of the bag, and the interior of the gland, are sterilized after manufacture by an appropriate sterilization technique, typically radiation. To ensure the integrity of the seal prior to filling the interface between the plug  22  and the gland  16  may be shaped and welded together as indicated in detail  136  to thereby define a frangible weld  138  at the interface. When it is desired to fill the bag the plug  22  will be removed from the gland  16 , breaking the weld  138 . However, during filling the region will first have been sterilized in the manner described above with reference to  FIGS. 1 to 20 . 
   After the bag has been filled the plug will be reintroduced into the gland  16 , but will be pushed further into the gland, to the position shown in  FIGS. 23 and 24  of the drawings. In this position the recess  122  will be located adjacent the rib  128  so that the rib  128  embeds itself within the elastomeric sealing ring  124 . 
   Preferably the elastomeric sealing ring  124  ring will have been heated during the closing procedure by sterilization steam introduced against the elastomeric sealing ring  124  after the plug has been partially introduced into the gland. This procedure is described in detail above. 
   After the elastomeric sealing ring  124  has been heated the plug  22  will be pushed further into gland  16  to the position shown in  FIGS. 23 and 24  wherein the rib  128  is embedded within the elastomeric sealing ring  124 . In this position, the elastomeric sealing ring will cool, and at least partially solidify to thereby lock and seal the plug  22  within the gland  16 . The material from which the elastomeric sealing ring  124  is made will therefore preferably be of a type which will partially melt plasticize at steam temperature in a relatively short period of time. 
   To remove the plug from the gland  16  the plug will be gripped and pulled outwardly thereby breaking the seal between the sealant  124  and the rib  128 . 
   There may be various alterations to the above-described embodiment without departing from the scope of the invention. For example, there may be a plurality of ribs  128  with a corresponding plurality of recesses  122 , each filled with a suitable sealant  124  to thereby improve the integrity of the seal. Similarly, the materials from which the plug, the gland, and the sealant are made could vary from that described herein. Also, necessary variations will need to be made where different packaging systems are employed. 
   It should be understood in this specification that the terms “up”, “down”, or “above” and “below” are not intended to indicate that the filling operation must be conducted in a particular orientation. Those terms are simply intended to assist with the description of the preferred embodiments and indeed it is envisaged that the system could well be used to fill horizontally or vertically or at an inclined angle. These terms should therefore not be in any way limiting on the ambit of the invention. 
   It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention. 
   The foregoing describes embodiments of the present invention and modifications, obvious to those skilled in the art can be made thereto, without departing from the scope of the present invention.