Abstract:
A system for storing food, including a plurality of food-containing packages disposed inside an endless high-density polyethylene wall for surrounding the plurality of food-containing packages and defining an airtight container. The high-density polyethylene wall is no less than one-quarter inch thick and is formed by engaging a heat source into thermal contact with container rim portion and a lid portion, energizing the heat source to partially melt both the rim portion and the lid portion, disengaging the heat source, and introducing the molten lid and rim portions into pressurized contact with one another to fuse them together to define the airtight container.

Description:
TECHNICAL FIELD 
       [0001]    The novel technology relates generally to the field of food packaging, and, more particularly, to a method and system whereby food to be preserved is first freeze-dried and compressed, and then sealed in a low-oxygen environment in a glass container. 
       BACKGROUND 
       [0002]    There are many reasons why storing food and other valuable items in a remote location for later consumption and/or use may be desirable. While there are many attractive long life storage containers and systems currently available, they all tend to be small and fragile. Thus, there remain needs for a storage system that can protect large volumes of food and other items for extended periods of times and under in adverse physical conditions. The present novel technology addresses these needs. 
       SUMMARY OF THE NOVEL TECHNOLOGY 
       [0003]    The present novel technology relates to a method and system whereby food to be preserved for indefinitely long periods of time is first packaged or freeze-dried and then sealed in a low-oxygen/low-moisture environment in a high density polyethylene container. One object of the present novel technology is to provide an improved food preservation system. Related objects and advantages of the present novel technology will be apparent from the following description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  is a perspective view of containers and sealing equipment according to a first embodiment of the present novel technology method for preserving food. 
           [0005]      FIG. 2  is an enlarged perspective view of the heat source shown in  FIG. 1 . 
           [0006]      FIG. 3  is an enlarged perspective view of a container and lid being prepressurized and/or heat treated according to the embodiment of  FIG. 1 . 
           [0007]      FIG. 4  is an enlarged perspective view of the container and lid being fused under pressure after heat treatment according to the embodiment of  FIG. 1 . 
           [0008]      FIG. 5  is an enlarged perspective view of a sealed container according to the embodiment of  FIG. 1 . 
           [0009]      FIG. 6  is a schematic view of the method according to the embodiment of  FIG. 1 . 
           [0010]      FIG. 7  is a time/pressure profile according to the embodiment of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]    For the purposes of promoting an understanding of the principles of the novel technology and presenting its currently understood best mode of operation, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the novel technology is thereby intended, with such alterations and further modifications in the illustrated device and such further applications of the principles of the novel technology as illustrated therein being contemplated as would normally occur to one skilled in the art to which the novel technology relates. 
         [0012]      FIGS. 1-7  illustrate a first embodiment of the present novel technology, a system  10  for preserving the integrity of foodstuffs and other perishable materials, typically foods  12  that have been packaged for preservation, in some instances freeze-dried and in other instances compacted for long term storage. The system  10  may also include dried and compacted food masses that have been enveloped in a partial vacuum formed inside a plastic or glass packaging. More typically, the food mass  12  is wrapped in a protective sleeve, such as a plastic film or the like, prior to positioning within the packaging. Individual packages  18 , such as presupplied Meals Ready to Eat (MREs) are placed into a container  20  that includes a central or canister portion  22  and a lid portion  24  sealedly connected thereto to define a substantially contiguous enclosure  20 . The enclosure or container  20  is typically made of high-density polyethylene (HDPE), high molecular weight polyethelene (HMWP), or the like. The enclosure  20  is typically no less than about ¼ inch thick. The canister portion  22  has an upper rim portion  25  defining an opening at one end. The portions  22 ,  24  are typically sealed by butt-welding the lid portion  24  to the rim portion  25  under pressure, but may alternately be sealed by suitable fusion or sealing techniques, such as laser or torch fusion (wherein a laser, torch or like device is used to sufficiently heat the intersection of the lid and central portions  24 ,  22  such that they flow together to form, when cooled, a contiguous enclosure  20 ), by the application of adhesives, or the like. Typically, water absorbing agents or desiccants  26  are placed in the enclosure  20  to further assure a substantially anhydrous environment therein, and, more typically, oxygen getters  27  are likewise placed in the enclosure  20 . 
         [0013]    In operation, the sealing process  100  begins with one or more food packages  18  (which may more generally include any package or item that is desired to be protected) being placed into the canister or barrel portion  22 . The canister or barrel portion  22  is typically cylindrical (more typically a unitary wall defining a cylinder having a bottom portion but no top lid portion), but may be of any convenient shape. More typically, the barrel portion  22  is between about eighteen and about forty-eight inches tall, still more typically between about thirty and about thirty-six inches tall, although the cylinder may be of other convenient dimensions. Next, a heat source, typically a double sided hot plate  105 , is preheated to a desired temperature sufficient to soften the container and lid material and then positioned in snug thermal contact  110  with the lid portion  24  and the rim portion  25 . The portions  24 ,  25  may be pressed  115  against the heat source  105  with moderate to high pressure. The heat source  105  is energized  120 , the applied pressure is typically reduced  122 , and the lid and rim portions  24 ,  25  are partially melted  125  to define molten lid and rim portions  130 ,  135 . The heat source is typically controlled so as to not overheat the HDPE, HMWP or like material and thus degrade its structural integrity. The heat source  105  is then removed  140 , and the molten lid and rim portions  130 ,  135  are introduced to one another under sufficiently high pressure  145  to fuse  150  the lid portion  130  to the rim portion  135  (and thus to the container portion  22 ) to define a sealed container system  10 . 
         [0014]    The hot plate  105  typically includes an electric heating element  160  positioned between a pair of thermally conducting disks  165  (typically, an anodized aluminum outer ring portion with an insulating ceramic center portion, such as perlite concrete or the like) connected in thermal communication therewith. The disks  165  more typically include an insulating nonstick layer  170 , such as polytetrafluoroethylene (PTFE), on the surfaces opposite the heating element  160 . The disks  165  assist in transferring sufficient heat directly to the portions  130 ,  135  to render them molten, without overheating the contents  18  of the container  20 . 
         [0015]    When desired, the system  10  may be accessed by breaking or removing the lid portion  24  from the canister portion  22 , such as with a pruning saw or powered circular saw or the like, or otherwise penetrating the container  20 . The contents  18  may then be removed and used. 
       EXAMPLE 
       [0016]    One or more packages  18  are placed  200  into a one-quarter inch thick HDPE barrel  22  about thirty inches high and having a diameter of about twenty four inches. A quarter-inch thick HDPE lid portion  24  is provided, wherein the lid portion  24  has a diameter of about twenty-four inches. A double sided hot plate heat source  105  including an electric heating element  160  positioned between a pair of thermally conducting disks  165  is positioned in snug thermal contact  110  with the lid portion  24  and the rim portion  25  of the barrel  22 . The portions  24 ,  25  are pressed  115  against the respective disks  165  under 950 PSI for about 1 minute. The pressure is decreased 122 to 450 PSI. The heat source  105  is energized  120  and preheated, and then engaged to heat the rim portion  25  and the lid portion  24  sufficiently to soften and partially melt  125  the lid and rim portions  24 ,  25  to define molten lid and rim portions  130 ,  135 . This requires a heat soak of about 1 minute, forty-five seconds. The heat source  105  is then quickly removed  140  (taking a total of about 10 seconds) and the molten lid and rim portions  130 ,  135  are immediately introduced  215  to one another and pressed against one another under pressure ramped up to 950 PSI over a period of about thirty seconds  220  to fuse  150  the lid portion  130  to the rim portion  135  (and thus to the container portion  22 ) to define a sealed container system  10 . It takes about 15-45 seconds, more typically about 30 seconds, to ramp the pressure up to 950, where the pressure remains applied for at least another two minutes and fifteen seconds, typically for about three more minutes. Once sealed, the system  10  is tested to withstand at least about 6 PSI pressure. The sealed container system  10  is typically stored for future use, such as warehoused or buried to a depth of at least about three to four feet (below the depth threshold wherein temperature is relatively constant year round to take advantage of a constant storage temperature of about fifty four degrees Fahrenheit), and, if desired, up to a depth of about thirty feet or more. The container system  10  is typically cylindrical to facilitate easy movement by rolling, and more typically features a corrugated outer surface to provide additional structural support. 
         [0017]    While the novel technology has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It is understood that the embodiments have been shown and described in the foregoing specification in satisfaction of the best mode and enablement requirements. It is understood that one of ordinary skill in the art could readily make a nigh-infinite number of insubstantial changes and modifications to the above-described embodiments and that it would be impractical to attempt to describe all such embodiment variations in the present specification. Accordingly, it is understood that all changes and modifications that come within the spirit of the novel technology are desired to be protected.