Abstract:
The present invention relates to a method for packing a material in a packing container. The method includes the steps of providing a gaseous atmosphere with superheated steam in a housing; supplying a material to the gaseous atmosphere and delivering a packing container to the gaseous atmosphere. Thereafter, the material is filled into the packing container, the packing container is sealed inside the gaseous atmosphere, and filled packing container is moved out of the gaseous atmosphere.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage filing of PCT/EP2008/006413 filed Aug. 5, 2008, claiming priority from Application DE 10 2007 037 606.7 filed on Aug. 7, 2007. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to a method and an apparatus for packing a material, especially a food product, in a packing container. 
       BACKGROUND OF THE INVENTION 
       [0003]    When a food product is packed in a packing container, it is usually desired to work with as few germs as possible, or indeed under sterile conditions, so that the packed product can be stored for a certain minimum storage time without any germs, bacteria or other micro-organisms that might be present inside the packing causing the product to spoil as a result of their proliferation. 
         [0004]    In practice, various approaches are known for this purpose. For example, the food product and/or the packing container may be subjected to an inert, sterile and/or bactericidal protective gas or bactericidal radiation before the packing process, though this entails certain disadvantages and, in many cases, a considerable amount of complex technical apparatus, without it being reliably possible to achieve sterile or virtually sterile packing in every case. 
         [0005]    The invention is based on the problem of creating a method and an apparatus for packing a material in a packing container with which, to the greatest possible extent, sterile packing can be achieved without excessive design or process engineering effort. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    From the point of view of process engineering, this problem is solved by a method for packing a material in a packing container, comprising the steps of providing a gaseous atmosphere with superheated steam in a housing, supplying a material to the gaseous atmosphere, delivering a packing container to the gaseous atmosphere, filling the material into the packing container, sealing the packing container, and moving the filled and sealed packing container out of the gaseous atmosphere. 
         [0007]    It is preferable that the temperature of the gaseous atmosphere should be more than 100° C., 120° C., 140° C., 160° C. or 180° C., at least in a horizontal sub-layer. The gaseous atmosphere may be at ambient pressure or at an elevated or reduced pressure. 
         [0008]    The gaseous atmosphere is conveniently a mixture of a first component, consisting of air and/or another gas, and water vapour as a second component, and has a steam content, at least in a horizontal sub-layer, of at least 50% by weight, 60% by weight, 70% by weight, 80% by weight, 90% by weight, 95% by weight, 98% by weight or 99% by weight, or consists only of steam. 
         [0009]    It may be provided that the material is dried for a certain time before packing by dwelling in the gaseous atmosphere for a predetermined period of time. 
         [0010]    The material can be packed in a tin or a screw-topped jar or in a film bag or pouch pack. In the latter case, it can be provided that the pouch pack is formed, filled and sealed inside the gaseous atmosphere, starting from a web of film, by means of a forming, filling and sealing apparatus. 
         [0011]    From the apparatus point of view, the problem of the invention is solved by an apparatus for packing a material in a packing container, comprising a housing for holding a gaseous atmosphere with superheated steam, the housing having an inlet port and an outlet port, a means for generating a gaseous atmosphere with superheated steam inside the housing, a first transport means for transporting the material through the inlet port into the housing and to a packing apparatus, the material being packed in a packing container by the packing apparatus, and a second transport means for transporting the material from the packing apparatus through the outlet port and out of the housing. 
         [0012]    In this context, it is proposed that the first and second transport means may be independent of one another or formed by part-sections of one and the same transport means. 
         [0013]    The inlet port can be on the same level as the outlet port. 
         [0014]    It can be provided that the inlet port is disposed at a free end of an inlet duct or guide channel which extends downwards from the housing. 
         [0015]    It can correspondingly be provided that the outlet port is disposed at a free end of an outlet duct or guide channel which extends downwards from the housing. 
         [0016]    It can be provided that a vent line communicates with the housing and has an exit aperture at a height below the housing and above the inlet port. 
         [0017]    It is conveniently proposed that there is an extraction line communicating with the housing and conducted via a fan to a condenser. 
         [0018]    It can be advantageous for the first transport means to support steam-permeable trays in which the material to be packed is held. 
         [0019]    Disposed along a partial section of the first transport means, there may be a conduit subjected to over-pressure or under-pressure, which communicates with a lower portion of the housing. 
         [0020]    In this context, a flow guide or sealing means may be disposed between the conduit and the partial section of the first transport means in order to ensure that there is a flow through the transport means, especially the trays. 
         [0021]    The packing apparatus can be designed as a forming, filling and sealing apparatus for pouches or film bags or as a filling and sealing apparatus for tins or jars. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Further advantages and features of the invention will become apparent from the following description of various working embodiments, reference being made to a drawing, in which: 
           [0023]      FIG. 1  shows a schematic perspective view of a first embodiment of an apparatus in accordance with the invention; 
           [0024]      FIG. 2  shows a side view of the apparatus according to  FIG. 1 ; 
           [0025]      FIG. 2   a  shows a side view of the apparatus according to  FIG. 1  in a variant; 
           [0026]      FIG. 3  shows an enlarged detail from  FIG. 2 ; 
           [0027]      FIGS. 3   a, b  show a detail from  FIGS. 1 to 3 ; 
           [0028]      FIG. 4  shows an embodiment of a means of tilting trays; 
           [0029]      FIG. 5  shows a perspective view of a first enlarged detail from  FIG. 2 ; 
           [0030]      FIG. 6  shows a side view of the apparatus according to  FIG. 5 ; 
           [0031]      FIG. 7  shows a detail from  FIG. 5 ; 
           [0032]      FIG. 8  shows a schematic plan view of a pouch pack as an example of a packing container; 
           [0033]      FIG. 9  shows a view of a transport means for pouches in the direction of transport; 
           [0034]      FIG. 10  shows a plan view of a section of the transport means with pouches held on it; 
           [0035]      FIG. 11  shows a plan view of a section of the transport means without pouches; 
           [0036]      FIGS. 12   a  and  FIG. 12   b  show side views of a tin or screw-topped jar as further variants of packing containers; 
           [0037]      FIG. 13  shows a view of a different transport means in the direction of transport; 
           [0038]      FIG. 14  shows a plan view of a section of the transport means according to  FIG. 13  with packing containers held on it; 
           [0039]      FIG. 15  shows a perspective view of a first variant of the apparatus according to  FIGS. 1 and 2 , with an extruder; 
           [0040]      FIG. 16  shows a side view of the apparatus according to  FIG. 15 ; 
           [0041]      FIG. 17  shows a side view of a second variant of the apparatus according to  FIGS. 1 and 2 , with a delivery station with a lock; 
           [0042]      FIG. 18  illustrates a variant of the invention; and 
           [0043]      FIG. 19  shows density values of superheated steam, dry air and moist air for different relative humidity values (rh). 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0044]    Referring now to  FIGS. 1 to 4 , first of all a first embodiment of an apparatus in accordance with the invention for packing a material, especially a food product, indicated as a whole by 1, is explained. 
         [0045]    The apparatus  1  consists first of a housing  2  with a bottom wall  4 , a right-hand side wall  6   a , a left-hand side wall  6   b , a rear wall  8 , a corresponding front wall, not shown, and a top wall  10 . Incorporated in the bottom wall  4  are a series of apertures for the transport means, which are still to be explained, to pass through. The bottom wall  4  is disposed substantially horizontally and consists, in the embodiment shown, of two bottom wall parts  4   a ,  4   b  positioned so as to slope slightly towards one another in a V-shape. The purpose of this arrangement is to allow condensate to flow to the connecting or transition area between the two bottom wall parts  4   a ,  4   b , which forms the lowest point of the interior space of the housing. 
         [0046]    The front wall, not shown, is substantially parallel to the rear wall  8  and abuts the lateral edges of the upper wall, the side walls and the bottom wall in such a manner as to create a seal, so that, apart from the apertures in the bottom wall  4 , the housing  2  surrounds an interior space which is enclosed on all sides. 
         [0047]    A transport means  12  extends through an inlet port  14  in the bottom wall  4  upwards in the direction of the upper wall  10 , runs horizontally along the upper wall, spaced apart from the latter vertically, and then back down in the direction of the bottom wall  4  and through a discharge aperture  16  from the housing. The transport means  12  bears a supporting means, which is not shown in detail in  FIGS. 1 to 3 , such as a belt, cable, chain or pair of chains, a number of bowls or trays  18 . Each tray  18  has a bottom wall  18   a  and a trough-like peripheral side wall  18   b  and is intended to receive a particular quantity of a food product to be packed. The bottom wall  18   a  and/or the side wall  18   b  is/are perforated or consist of a rib mesh or the like, in order to permit the gaseous atmosphere present in the housing  2  to pass through unhindered. 
         [0048]    Instead of the trays, a conveyor belt can be provided as the transport means, on which the material to be processed is located, e.g. a flat conveyor belt or one which, seen in cross-section, is concave like a trough, possibly perforated. 
         [0049]    The supporting means of the transport means  12  can be guided, via deflection pulleys with a horizontal axis of rotation for example, which may be disposed in the region of deflection points  20 , not far from the upper wall  10 . 
         [0050]    The trays  18  are each conveniently hung on the supporting means on a horizontal pivoting axis  22  running above their centre of gravity, allowing them to swing freely in pendulum fashion, so that they maintain their upright orientation with their bottom walls facing downwards despite the changes in direction of the supporting means. 
         [0051]    In the region of a horizontal transfer conveyor  26  running across the direction of movement of the transport means  12 , the trays  18  can be tilted about the pivoting axis  22  so that their contents pass via a guide plate  28  onto the upper portion of the transfer conveyor  26 . In the process, the trays may be tilted by 120°,150° or 180°. After passing through the region of the transfer conveyor  26 , the trays are tilted back to their original alignment. For this purpose, projecting dogs, such as pins or the like, may be provided on the trays, transverse to the direction of transport  13 , which co-operate with stationary or movable actuation members or control surfaces in order to tilt the trays. 
         [0052]      FIG. 4  illustrates a variant of the transport means  12  for actuating the tilting movement of the trays  18 , which also forms the basis for the representation in  FIGS. 1 and 2 . The supporting means  24 , a pair of chains guided in parallel for example, is guided along the path shown and connected to trays  18  at regular distances via pivotable suspensions  24   a . The trays each have a pair of guide lugs  24   b , which are guided in guide rails  25 . In the region of the transfer conveyor  26 , the guide rails  25  are spaced apart differently from the supporting means  24 , which results in the tilting or pivoting movement of the trays  18  shown in  FIG. 4 , so that the material held therein passes to the transfer conveyor  26 . The trays are moved out of the discharge aperture in a discharge position (bottom wall up) which is rotated by 180° relative to the delivery position. 
         [0053]    A discharge end  30  of the transfer conveyor  26  is located above one end of an arrangement of buffer conveyor belts  34   a ,  34   b ,  34   c , the respective ends of which are disposed above one another and staggered and are designed for conveying products placed on them by the transfer conveyor  26  in opposite conveyance directions  36 , so that a buffering or storage effect results. A discharge end  38  of the lowest buffer conveyor belt  34   c  is disposed above a receiving hopper  40  of a packing apparatus  50  shown by way of example. In the embodiment shown, the packing apparatus  50  has the necessary means for packing food products in screw-topped jars. 
         [0054]    For the purpose of packing food products in screw-topped jars, a further transport means  60  is provided, which extends through an entry port  62  in the bottom wall  4  upwards in the direction of the upper wall  8  and is deflected back downwards at a deflection point  64  in the area of the upper wall  8 , in order to be deflected into a horizontal direction on a level located between the upper wall and the bottom wall at a deflection point  66 . The packing apparatus  50  is disposed in the region of a horizontal section of the transport means  60  adjacent to the deflection point  66  (and after a horizontal deflection  67 ). After passing the packing apparatus  50 , the transport means  60  runs through a further deflection point  68  and leaves the housing downwards through an outlet port  70  in the bottom wall  4 . 
         [0055]    The transport means  60  has a supporting means  72 , which can be designed in the form of a single strand-like, flexible element, which absorbs tensile forces, like a belt, rope or chain, or in the form of two such elements, which are disposed parallel and spaced apart from one another. Holding means for receiving a packing container, in this case a screw-topped jar, are disposed on the supporting means  72  at regular mutual intervals. 
         [0056]    Whereas  FIG. 3  shows an enlarged representation of a section of the transport means  60  in the form of a side view, the supporting means  72  is illustrated in greater detail in  FIGS. 13 and 14 . In this embodiment, it has two parallel strands of chain  74 , to each of which is attached a flexible holding means  76 . The two holding means  76  are provided with undulating contours symmetrically to a longitudinal central plane of the transport means  72 , and consist of a material with a high coefficient of friction with regard to the packing containers to be held, so that the latter are held securely when the strands of chain  74  are guided at a fixed distance from one another.  FIG. 14  shows a plan view of a detail of the supporting means with three packing containers held on it, while  FIG. 13  shows a sectional view in the direction of conveyance or transport.  FIGS. 12   a  and  12   b  are a schematic side view of a tin  78  and a screw-topped jar  79 , of the kind that can be transported by the transport means illustrated in  FIGS. 13 and 14 . Although they are illustrated in strands of chain  74  as chains or roller chains with chain studs, which run in the same plane as the strands of chain  74 , it goes without saying that the strands of chain are flexible in two directions which are perpendicular to one another if necessary. 
         [0057]    An alternative possibility of delivering the food product to be packed into the housing is illustrated in  FIGS. 15 and 16 . As the first transport means in this case for transporting the food product into the housing, an extruder  80  is provided, which in this case is designed as a so-called boiler-extruder, i.e. in which and/or at the outlet from which where the product enters the housing a temperature of 100° C. is reached or exceeded, so that the extruded product already possesses a considerably reduced germ count. The extruder  80  leads into the housing  2  near the upper wall  8  and works onto an intermediate conveyor  82 , which transfers the extruded material via a guide plate  28  onto the buffer conveyor belts  34   a, b, c , which have already been described, from where, as previously described, it reaches the packing apparatus  50 . 
         [0058]    This embodiment offers the advantage that it is possible to work in an unbroken sterile or low-germ manner, since the product no longer comes into contact with ambient air after extrusion, as becomes clear from the following description of the gaseous atmosphere. 
         [0059]    In the embodiment shown here, the packing apparatus  50  has three stations, namely a receiving station, formed here by the receiving hopper  40 , then an addition station, formed here by an addition line  52 , which is directed outwards from the housing, and with which one or more additives, e.g. flavour enhancing substances or probiotic additives, can be added to a product introduced into a respective packing container at the receiving station, and then also a sealing station with a sealing apparatus  54 , with which the respective packing container is sealed, in this example by means of a screw cap in each case. 
         [0060]    The screw cap or the lid to be placed on the open tin and knurled shut may have a transparent portion in the form of a window, so that the surface of the product inside the packing container is visible from the outside. The transparent portion can extend over the greater part of the lid, apart from an edge portion of metal or plastic which is necessary for screwing on or knurling. 
         [0061]    As a further variant instead of a screw cap, a sealing lid can be provided in the case of a jar or tin which is not kept in place by a positive lock (screw thread or knurling), but rather solely by the atmospheric over-pressure relative to the partial vacuum inside the finished packing container. For this purpose, the lid can be provided along its outer circumference with a resilient sealing material which, after the lid is placed on top, co-operates with an upper edge of the packing container in a sealing fashion and seals the lid under the effect of the atmospheric pressure. 
         [0062]    As is already suggested by  FIGS. 1 to 3 , the screw-topped jars  79  are introduced into the housing in a position in which they are open at the bottom, i.e. with their floors, shown thicker, facing upwards. As a result, the ambient air contained in the jars is given the possibility of flowing out, since the steam atmosphere is lighter in terms of its specific gravity, so that the screw-topped jars are filled with steam in the desired manner. In order to be able to continue this process as far as the deflection point  66 , and so that the jars have their open ends facing upwards in the region of the packing apparatus  50 , where they are filled, they are rotated by 180° in the region of the deflection point  64 .  FIGS. 3   a  and  3   b  illustrate this schematically. Before or after or even in the region of the deflection point  64 , there is a twist  56 , illustrated by way of example by four wire guides  58 , which are bent in a helical manner and each of which extends over 180°. An empty packing container delivered at one end of the twist, the floor of which is shown schematically thicker and which is at the bottom, is guided loosely by the wire guides  57  as it runs through the twist and is rotated by 180° in the process, so that the position illustrated results at the other end of the twist (see also  FIGS. 2   a  and  17 ). 
         [0063]    The transfer of the packing containers—from the parallel strands of chain  74  ( FIGS. 13 ,  14 ), for example—to the twist and vice versa might be effected in that, when entering the twist, the strands of chain  74  are guided apart and then guided back together again at the end of the twist, in order to release the packing containers and receive them again. Alternatively, after entering the twist, the strands of chain  74  can be lowered and then raised again in the region of the end of the twist, in order to release the packing containers and receive them again. 
         [0064]    Although two transport means are provided in the examples shown, which are constructed separately from one another and work independently of one another, namely the transport means  12  and the further transport means  60 , it could be contemplated to replace them by a single transport means which runs past a packing apparatus. The packing containers needed could then either be taken from a store present inside the housing, which would have to be filled at certain intervals, or would have to be supplied from outside by means of a feeder means. 
         [0065]    As an alternative to packing in tins or screw-topped jars, the further transport means  60  can be designed, as  FIGS. 5 to 11  show, for transporting pouches  86 , which consist, in a manner known per se, of two rectangular sections of film  88 , which are sealed together on two or three sides, so that one filling edge  90  of the pouch is still open. The pouches  86  are held on both sides by a pair of grippers  92 , which for their part are attached to gripper chains  94 . After being filled with the food product, the pouches are sealed with a sealing apparatus disposed inside the housing  2  along the filling edge  90  by thermoplastically welding the two sections of film using a heated sealing rod or by ultrasound. 
         [0066]    As  FIGS. 5 to 7  show, the pouches serving as packing containers can be produced, filled and sealed directly inside the housing  2  with a forming, filling and sealing apparatus which is known per se. By way of explanation of this approach, which is known per se,  FIG. 7  shows first of all, in an enlarged detail, a roll of film  100  disposed outside the housing  2 , from which web-like film material  102  is drawn. The film material  102  is guided via deflection rollers  104 ,  106  and  108  in the direction of the upper wall  8  of the housing  2  and then runs through two fixed deflection rollers  110 ,  112  and a compensating roller  114  arranged between them, which is movable in a vertical direction and which serves to ensure that the film material  102  runs smoothly. 
         [0067]    After passing across a further deflection roller  116 , the film material  102  is brought to rest against a cylindrical outer surface of a charging tube  120 , which is provided at an upper end with a receiving hopper  40 . Means, which are not shown in detail, for welding the film material in the machine direction and cross-machine direction serve to produce individual film bags which, after filling and sealing, pass through the outlet port  70  onto a removal conveyor means  124 , in the course of which the cooling of the filled pouches by means of a cooling apparatus  126  can be accelerated. 
         [0068]    In order to generate a desired gaseous atmosphere with superheated steam inside the housing  2 , such as is described in U.S. Pat. No. 5,711,086, there is a heating apparatus  130  ( FIGS. 1 ,  2 ,  5 ,  6 ,  15 ,  16 ), which can take the form of an electric heating element or heat exchanger and is disposed inside a conduit  132 , via which it is coupled to the housing  2 . The conduit leads, on the one hand, into an aperture  133  in the upper wall  8  and, on the other hand, into an aperture  134  in the rear wall  10 . In order to generate a flow through the heat exchanger  130  a fan  136  is disposed in the conduit  132 , with which a flow can be generated in the direction of flow  138 . Although the aperture  134  is illustrated at a relatively low position inside the housing  2 , i.e. in the vicinity of the bottom wall  4 , it can be disposed higher up, such as in the region of the upper wall  8 , immediately below the transport means  12 , and possibly, when seen in the direction of transport  13 , staggered by a certain distance relative to the aperture  133  in the upper wall  8 , into which the conduit  132  leads, in order to avoid a short-circuit effect. The housing  2  can be provided with inlet and outlet ducts, through which the transport means extend, and a vent line, as explained in  FIG. 2   a.    
         [0069]    In order to accelerate or intensify the generation of the desired gaseous atmosphere, a steam feed line, not shown, can be used to introduce superheated steam directly into the housing  2 . Alternatively, it can be provided that a steam or water feed line, such as a water atomiser, leads into the conduit  132  upstream of the heating apparatus  130 , so that by heating the steam or evaporating the water, a superheated steam atmosphere can be introduced in the region of the aperture  134 . 
         [0070]    Beneath the aperture  132 , baffle plates  140  facing each other are attached to the upper wall  8  as flow guides or sealing means, which are intended to ensure that the steam atmosphere extracted from the housing  2  through the aperture  133  first flows to the greatest possible extent through the perforated tray or trays  18 , which are located just below the aperture  133 . This ensures that the product located in the trays comes into intimate contact with the superheated steam. In the embodiment according to  FIGS. 15 ,  16 , two horizontal baffle plates  140  are provided, it being possible for the intermediate conveyor  82  to have a perforated carrying belt, in order to enable steam to pass through in the best possible manner. 
         [0071]    Two further baffle plates  142 ,  144  ( FIGS. 1 ,  2 ,  5 ,  6 ) are arranged substantially parallel to the left-hand side wall  6   b  and overlapping with a slight space between them. The task of these baffle plates is, as far as possible, to prevent excessive amounts of ambient air being introduced into the housing  2  by the moving transport means  12 . A gap between the baffle plates in the vicinity of the bottom wall  4  allows air or an air-rich steam atmosphere of relatively high density to escape. 
         [0072]    A further guide plate  146  serves to remove ambient air or steam with a large proportion of ambient air through the aperture  62 , since it is unavoidable that a certain amount of air enters the housing together with the containers  79 . 
         [0073]    Alternatively or in addition, a nozzle-like flow guide for the steam can be provided by means of a narrowing, in order to cause a local increase in the flow speed and thus improved contact with the product. 
         [0074]    Since an uncontrolled exit of the steam atmosphere from the housing  2  is undesirable, an extraction line  150  is provided, which leads into an extraction port  151  in the rear wall  8  immediately above the bottom wall  4  and leads to a condenser  152 , from where the water condensed out is directed into a container  154 . Extraction is effected by a controlled fan  160 , which is controlled by information on the temperature and humidity or steam content. For this purpose, temperature and steam content sensors are arranged in the housing, preferably one temperature sensor and one moisture or steam content sensor in the vicinity of the upper wall  10  and near the bottom wall  4  or near the extraction port  151 . The extraction port  151  can be provided in the bottom wall  4  or at any height above that. The lower it is located, the lower is the temperature of the steam extracted. 
         [0075]      FIG. 2   a  illustrates a variant of the apparatus according to  FIGS. 1 and 2 , in which first of all saturated steam and thus surplus moisture can be guided out of the housing via a vent line  153  as an alternative to extraction via the extraction port  151 , or both. The vent line  153  communicates with a three-way valve  155 , which further communicates via a conduit  156  with the extraction line  150  and with a further conduit  157  with a port  158  in the bottom wall  4 . The vent line  153  has a venting aperture  159  leading to the surroundings. 
         [0076]    The three-way valve  155  can be placed in a first position, in which the lines  156  and  157  communicate, while the line  153  is sealed off, so that extraction takes place via the ports  151  and  158 . If desired, a check valve may be provided in the line  156  in order to be able to ensure that in the first position of the three-way valve, extraction occurs exclusively via the port  151 . 
         [0077]    The three-way valve  155  can be placed in a second position, in which the vent line  153  communicates with the conduit  157 , while the conduit  156  is sealed off and the fan  160  is switched off, so that the steam atmosphere within the housing communicates with the surroundings via the port  158  and the conduits  157  and  153 . 
         [0078]    Unlike the apparatus according to  FIGS. 1 and 2 , the apparatus illustrated in  FIG. 2   a  has a number of guide channels  42 ,  43 ,  44  and  45 , which extend the housing downwards in the region of the holes in the bottom wall, namely the inlet port  14 , the discharge aperture  16 , the entry port  62  and the outlet port  70 , and terminate openly at substantially the same height. The guide channels surround the transport means  12  and  60  at the inlet and outlet ends and, together with the vent line  153 , which terminates at a higher level, cause surplus steam to be discharged from the interior of the housing  2  via the vent line  153 , in the second position of the three-way valve  155 . The steam present inside the housing has a tendency to flow downwards through the guide channels, but in the process it encounters relatively cold ambient air, so that a substantially horizontal boundary layer forms in all the guide channels at the height of the venting aperture  159 . The height h 0  at which the venting aperture  159  is located above the height of the free end of the guide channels may, for example, 10%, 20%, 30% or 50% of the height H of the housing, H referring to the vertical distance between the highest and lowest point of the interior of the housing. In addition, the height h 0  is preferably between about 30% and 70%, e.g. 50%, of the vertical extent hb of the guide channels, beginning at the lower wall  4  or the lowest point of the housing. 
         [0079]    In all embodiments, a height hs of the extraction port  151  above the lower wall  4  of the housing or the lowest point of the housing may be virtually zero in effect, or it may be about 5%, 10%, 15%, 20% or 30% of H. A height ht at which the actual drying process mainly takes place and at which or above which the horizontal sub-layer is preferably located, in which the gaseous atmosphere is of the desired high temperature and exhibits low oxygen values, may be about 50%, 60%, 70%, 80%, 90% or 95% of the height H of the housing, measured in each case from the lower wall of the housing  4  or the lowest point of the housing. 
         [0080]      FIG. 17  shows a side view of a second variant of the apparatus according to  FIGS. 1 and 2 , where the product to be treated, similar to the first variant, is not transported into the housing via the first transport means  12 , but is rather conveyed via a delivery means  170 , which is connected to the housing, and a lock, in this case a cellular wheel sluice  172 , directly in the upper part of the housing  2  and thus in the region of the hottest superheated steam onto the first transport means  12 , in this case into individual trays  18  of the first transport means, the further process being as in  FIGS. 1 and 2 . 
         [0081]    The delivery means  170  has a pressure reservoir  176  which can be filled by a lock  174  and into which steam can be admitted for sterilisation purposes. The sterilisation time is dependent on the temperature of the steam and the F 0  value required, i.e. the desired sterilisation quality. After the desired F 0  value has been reached, the pressure reservoir is depressurised via a valve, and the product is conveyed via the lock  172  directly into the housing  2 . 
         [0082]    The delivery means  170  is particularly suitable for delivering pieces of product produced by machine, which may, for example, contain meat, artificial meat, cereals etc. Thanks to the manufacturing process without extrusion, it is possible to preserve a coagulated protein structure in the pieces of product. 
         [0083]    The temperature of, for example, 120° C. to 180° C. prevailing in the housing  2 , at least in a horizontal sub-layer accounting for part of the height H, prevents renewed contamination with micro-organisms before the packing containers are sealed. 
         [0084]    The steam in the pressure reservoir  176  required for sterilisation can be removed from the housing  2  and raised to a higher energy level by means of a compressor. 
         [0085]      FIG. 17  also shows an extraction unit  180  for volatile substances, such as flavours, contained in the condensate which accumulates in the condenser  152  and is collected in the container  154 . 
         [0086]    Since it would be very difficult to extract the volatile substances contained in the steam extracted through the extraction port  151  directly from the steam phase, this is done in a manner known per se by means of a rotating-table column or rotating-cone column, also referred to as a spinning cone column, SCC, which is the most important element of the extraction unit  180 . 
         [0087]    The condensate containing the substances to be extracted is delivered to the unit  180  via delivery line  182 , which bears a number of rotating, cone-shaped plates  186  mounted on a rotating shaft  184 . Between each two rotating plates there is a fixed, likewise cone-shaped plate  188 , which is connected in each case to the outer, closed housing  190  of the apparatus. 
         [0088]    In addition to the product to be treated, steam and/or inert gas  192  are supplied to the extraction unit in the opposite direction to the product. Escaping steam with volatile substances which have not been deposited or extracted is indicated by  194 . 
         [0089]    Extracted substances can be removed at the bottom of the unit at a product outlet  196 . 
         [0090]    The volatile substances extracted, such as flavours, can either be added to the product to be packed, as indicated by  199 , such as in the form of a gravy, or may be put to some other use. This kind of extraction can be used advantageously with any embodiment of the invention. 
         [0091]      FIG. 18  illustrates a modification of the invention which can be used in all the embodiments described above, and in which—unlike the embodiments illustrated in FIGS.  1  to  3 —the aim is not to have a distinct horizontal succession of layers with a steam atmosphere that, moving from bottom to top, becomes warmer, poorer in air and oxygen and increasingly containing only superheated steam, but rather a steam atmosphere which is mixed as thoroughly as possible and homogenised within the entire housing. This is achieved in that the interior of the housing is evenly mixed with the aid of at least one circulation fan  210  ( FIG. 18  shows two of them), so that virtually no stratification or uneven mixing can become established in the vertical direction. 
         [0092]    In addition, the contact between the material to be dried and the steam atmosphere is improved with a forced circulation system consisting of a cyclone  212 , a fan  214 , a heat exchanger  216 , fans  218   a, b, c  and, connected to them, steam guide boxes  220  a, b, c. Depending on what is more appropriate, the cyclone  212 , fan  214 , heat exchanger  216  and fans  218   a, b, c  may be disposed inside or outside the housing  2 . Depending on the flow conditions, either the fan  214  or the fans  218   a, b, c  may be dispensed with. The fan  214  sucks in the steam atmosphere across the cyclone  212  upstream, in which particles originating from the material to be dried are deposited. The cyclone for its part sucks in the steam atmosphere at any suitable point or area within the housing. After the fan  214 , the steam atmosphere flows through the heat exchanger  216 , having optionally been enriched with steam beforehand by means of a steam generator  215 . In the heat exchanger  216 , heat may be supplied or removed as required, whereupon the steam atmosphere then enters the steam guide boxes  220   a, b, c  via the fans  218   a, b, c . The steam guide boxes guide the steam atmosphere through a preferably perforated conveyor belt of the transport means  30 , so that the material on it is brought into intimate contact with the steam atmosphere. 
         [0093]    Since different techniques for introducing the material to be dried into the housing are described in  FIGS. 1 to 3 ,  15  and  17  (transport means with trays, extruder und delivery station with a lock), the delivery of the material to be dried and packed is merely indicated in  FIG. 18 . In the variants described in  FIGS. 15  und  17 , the steam guide boxes  220  could be used in the form illustrated in  FIG. 18 , whereas in the embodiment according to  FIG. 1 , an adaptation to the transport means with trays is possible, for example in the manner of the flow guide or sealing means  140  (guide plates), or they could be used in connection with the transfer conveyor  26  or the buffer conveyor belts  34 . 
       LIST OF REFERENCE NUMERALS 
       [0000]    
       
           1  Apparatus 
           2  Housing 
           4  Bottom wall 
           4   a, b  Bottom wall part 
           6   a, b  Right-hand, left-hand side wall 
           8  Rear wall 
           10  Upper wall 
           12  Transport means 
           13  Direction of transport 
           14  Inlet port 
           16  Discharge aperture 
           18  Tray 
           18   a  Bottom wall 
           18   b  Side wall 
           20  Deflection point 
           22  Pivoting axis 
           24  Supporting means 
           24   a  Suspension 
           24   b  Guide lugs 
           25  Guide rail 
           26  Transfer conveyor 
           28  Guide plate 
           30  Discharge end (of  26 ) 
           34   a, b, c  Buffer conveyor belt 
           38  Discharge end 
           40  Receiving hopper 
           42 - 45  Guide channel 
           50  Packaging apparatus 
           52  Addition line 
           54  Sealing apparatus 
           56  Twist 
           58  Wire guide 
           60  Transport means 
           62  Entry port 
           64 , 66  Deflection point 
           67  Horizontal deflection 
           68  Deflection point 
           70  Outlet port 
           72  Supporting means 
           74  Strand of chain 
           76  Holding means 
           78  Tin 
           79  Screw-topped jar 
           80  Extruder 
           82  Intermediate conveyor 
           86  Pouches 
           88  Section of film 
           90  Filling edge 
           92  Gripper 
           94  Gripper chain 
           100  Roll of film 
           102  Film material 
           104 ,  106 , Deflection roller 
         
           108 
         
           110 ,  112  Deflection roller 
           114  Compensating roller 
           116  Deflection roller 
           120  Charging tube 
           124  Removal conveyor means 
           126  Cooling apparatus 
           130  Heating apparatus 
           132  Conduit 
           133 ,  134  Aperture 
           136  Fan 
           138  Direction of flow 
           140  Guide plate 
           142 ,  144  Guide plate 
           146  Guide plate 
           150  Extraction line 
           151  Extraction port 
           152  Condenser 
           153  Vent line 
           154  Container 
           155  Three-way valve 
           156  Conduit 
           157  Conduit 
           158  Port 
           159  Venting aperture 
           160  Fan 
           170  Delivery means 
           172 ,  174  Lock 
           176  Pressure reservoir 
           180  Extraction unit 
           182  Delivery line 
           184  Shaft 
           186  Rotating plate 
           188  Fixed plate 
           190  Housing 
           192  Steam inlet 
           194  Steam outlet 
           196  Product outlet 
           198  Feed line for extracted substances 
           210  Circulation fan 
           212  Cyclone 
           214  Fan 
           215  Steam generator 
           216  Heat exchanger 
           218   a, b, c  Fan 
           220   a, b, c  Steam guide box