Abstract:
Methods and apparatus utilizing a high pressure food package involving filling a cup with a quantity of food product chosen so as to be capable of absorbing sufficient CO2 to produce effervescence easily detectable by a person later removing and consuming the food product, introducing CO2 into the cup, closing the lid, pressurizing the interior space with CO2 and generating sufficient effervescence in the food product, applying an anti-tamper feature to the closed cup, allowing the internal pressure of CO2 to increase and stabilize, transporting and holding the package for retail sale, providing means for a consumer to depressurize the package before removing the lid, and providing means for a consumer to hold the cup in one hand and twist off the lid with another hand, and to use fingers of one hand to remove the carbonated food product from the cup.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. provisional application Ser. No. 61/667,434 filed on Jul. 3, 2012. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The disclosure herein generally relates to designs for a high pressure food package and system and, more particularly, to designs for a modified atmosphere food package that is capable of retaining a high internal pressure, releasing that pressure safely, and methods for using the same. 
     BACKGROUND OF THE INVENTION 
     Modified atmosphere packaging generally refers to the practice of modifying the composition of the internal atmosphere or headspace of a package in order to improve the shelf-life of the product. The product is typically a food product but may also include pharmaceuticals or other types of products. The modification usually involves attempts to lower the amount of oxygen in order to slow down the growth of aerobic organisms and the speed of oxidation reactions. The removed oxygen is typically replaced with nitrogen, commonly known as an inert gas, or carbon dioxide, which can lower the pH or inhibit the growth of bacteria. 
     In the context of food products, modified atmosphere packaging is generally considered a technique used for prolonging the shelf-life of fresh or minimally processed foods. In this preservation technique, the air surrounding the food in the package is changed to another composition using, for example, a gas-flush process. The initial fresh state of the food may be prolonged by slowing the natural deterioration of the food product. Respiring foods such as fruits and vegetables continue to take in oxygen and give off carbon dioxide as they continue to respire and ripen after harvest. Refrigeration and controlled atmosphere storage methods may be used to retard the ripening process. Reducing temperature slows the produce metabolism, including the rate of respiration. Under controlled atmosphere storage, respiration and ripening may be reduced further by lowering the oxygen content of the air, which normally consists of approximately 21% oxygen, 78% nitrogen, and 1% other elements. 
     A recent need for using modified atmospheres, specifically carbon dioxide (CO2), is to enhance the flavor of foods by creating an effervescent character during tasting (e.g. U.S. Pat. No. 5,968,573, which is incorporated herein by reference). This method involves the generation of positive CO2 pressure within a sealable container filled with food such that the CO2 diffuses by osmosis into the water content of the food. The development of carbonated foods (e.g. Fizzy Fruit™) has created a need for a safe and convenient package to distribute single servings. 
     One example of a package directed to retaining a positive pressure atmosphere within the package is a tennis ball can (or tennis ball tube). The air pressure inside a tennis ball is typically 12 psi (pounds per square inch) greater than the ambient air pressure at sea level. Over time, air escapes from the inside of the ball causing a decrease in the amount of air pushing on the inside of the ball and, consequently, decreasing the bounce characteristics of the ball. To prevent the ball from becoming “flat,” the ball is packaged in a positive pressure tube, with the tube pressurized to around 12 psi, which is enough to prevent air from escaping from the inside of the ball. Another example of a positive pressure package is the ubiquitous soda bottle, which is directed to maintaining carbon dioxide saturated liquid under pressures of up to 50 psi. 
     Designs for a high pressure food package and system that provides a sufficiently pressurized and controllable gaseous environment are needed. Such designs need to be applicable for use with the carbonated fruits or vegetables products described in U.S. Pat. Nos. 5,968,573 and 7,228,793, and U.S. patent application Ser. Nos. 10/857,043, 11/453,712, 11/454,814, 11/548,212, 11/943,964, and 12/271,797, all commonly owned or licensed by The Fizzy Fruit Company and each of which is incorporated herein by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       For a more complete understanding of the present invention, the drawings herein illustrate examples of the invention. The drawings, however, do not limit the scope of the invention. Similar references in the drawings indicate similar elements. 
         FIG. 1A  is a sectional side view of an exemplary high pressure food package and system. 
         FIG. 1B  is a detail sectional side view of a seal and thread region of the high pressure food package and system of  FIG. 1A . 
         FIG. 2  is an exemplary schematic for a pneumatic system for use with the high pressure food package and system of  FIG. 1A . 
         FIG. 3A  is a cut side view of an exemplary high pressure food package having a one-way valve and an overpressure feature. 
         FIG. 3B  is a cut bottom view of the lid portion of the high pressure food package of  FIG. 3A . 
         FIG. 3C  is a detail sectional view of the one-way valve region of the lid of  FIG. 3A . 
         FIG. 4A  illustrates top and cut side views of an exemplary lid with a puncture pin mechanism for releasing internal pressure prior to opening the package. 
         FIG. 4B  is a side view of an exemplary lid which serves as an adapter between a wide access point, and a more narrow filling point capable of fitting into existing soda bottle manufacturing standards. 
         FIG. 4C  is a side view of an exemplary lid with a poppet-style valve through which CO2 gas can be loaded into the package during filling and production, and also by which the consumer can release internal pressure prior to opening the package. 
         FIG. 5  illustrates exemplary simplified basic internal CO2 pressure and typical timing profiles involved in a retail package, and an exemplary effervescence (or Fizzy) rating scale. 
         FIG. 6  is a concept map of various explored variables and design factors in a retail food carbonation system. 
         FIG. 7  illustrates top and cut side views of another exemplary high pressure food package having a lid with a rim gripping seal and pressure releasing pull-tab. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the preferred embodiments. However, those skilled in the art will understand that the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternate embodiments. In other instances, well known methods, procedures, components, and systems have not been described in detail. 
     Various operations may be described as multiple discrete steps performed in turn in a manner that is helpful for understanding the preferred embodiments. However, the order of description should not be construed as to imply that these operations are necessarily performed in the order they are presented, nor even order dependent. Lastly, repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. 
     As an overview, the present inventors determined that designs for a high pressure food package and system are needed that provide a package with a sufficiently pressurized and controllable gaseous modified atmosphere for a quantity of food product, such as, for example, fresh-cut fruits or vegetables, yet at the same time remains safe, easy to open and use, re-sealable, and portable. However, the present inventors discovered that some types of packaging are less desirable because: the package may have too small of an opening to allow for easy access to food pieces (i.e. the package was designed (by others) for other types of (liquid) products); the package is not capable of maintaining the positive pressure levels necessary to effectively enhance the flavor of foods (i.e. effervescence); and/or the package comprises materials and methods that do not readily fit into the recycling stream. For example, one package under development for carbonating foods uses an aluminum lid seamed to a plastic cup. This makes recycling more difficult because of the tight weld between the two materials, which cannot be separated easily enough using existing reclaiming methods. This aluminum/plastic type of package may also create potentially dangerous metal edges if the package were to burst open from too much internal pressure, for example from internal fermentation of the food product. Consequently, the present inventors determined that not only is it desirable that the new package hold sufficient internal pressure, but it is desirable that the new package be capable of automatically releasing excessive internal pressure. 
     The present inventors discovered that for some types of packaging, once a container with a fixed amount of food is initially pressurized to its maximum level with gas and then sealed, the gas in the head space will gradually diffuse into the tissues of the food product and reduce the overall internal pressure within the package. The reduced internal pressure level may not be sufficient to produce the intended strongly enhanced or effervescent flavor profile for the particular food product. In testing one embodiment of the aluminum/plastic type package described above, after the initial gas pressurization to the package&#39;s maximum capability (i.e. approximately 35 psi), the pressure equilibrates after diffusion into the tissues of the food product so as to reduce the internal pressure of the package to only about 20 psi, resulting in weaker effervescence than desired. 
     The present inventors further discovered that with various other methods for enhancing food flavor with carbon dioxide, the level of carbonation (or absorbed carbon dioxide) varies with the internal pressure of carbon dioxide during the step of maintaining the internal pressure within the package or container. The inventors discovered that this relationship can be controlled by pressure devices that are capable of setting a specific internal pressure level of carbon dioxide, and that this resulted in an effervescent (or “fizzy”) tasting intensity that can be reproduced more reliably. A “fizziness” scale from 1 to 5 (with 5 being the most effervescent) was developed by the inventors to qualitatively describe this relationship to internal CO2 pressure. However, the inventors determined that existing packaging systems are not capable of controlling and maintaining the internal pressure level at specific levels, especially high levels. 
     The present inventors invented a high pressure food package and system that provides, in various embodiments: a high pressure food package comprising a sealable container having a wide mouth cup and lid, the sealable container suitably designed for holding a quantity of non-liquid food product, and an integral or separate gas seal within the sealable container capable of retaining and maintaining a positive pressure within the sealable container, the gas seal configured so that the positive pressure inside the container energizes (i.e. makes stronger) the seal. The system includes a collar and apparatus capable of holding the container and filling the container through its seal during partial closure of the lid onto the cup with a desired quantity of gas to create a specific sensory level of effervescence. 
     Various embodiments are described, some of which incorporate features for manual or automatic release of, possibly excessive, internal pressure prior to opening. Excessive internal pressure might be caused by heating, pressure differentials, internal fermentation of the product contained, or other factors. 
     In one embodiment, the package is capable of providing a pressurized carbon dioxide rich atmosphere, initially to approximately 60-90 psi, and equilibrating to approximately 40 psi, for carbonating or maintaining the carbonation of a quantity of food, such as fruits or vegetables. In one embodiment, an optimum amount of oxygen is provided in the gas mixture to avoid dangerous anaerobic conditions if the food product is not itself inherently toxic (e.g. acidic) to such pathogens. The gas mixture may comprise a predetermined combination of CO2 and O2. For example, the gas mixture may comprise 95% CO2 and 5% O2 in order to provide an effervescent character to the food product yet prevent anaerobic microbial growth (e.g.  C. botulinum ). 
     In one embodiment and a separable aspect, a collar apparatus holds the cup down with a vacuum while filling through the threaded seal and partially closed lid the desired volume and composition of gasses internally. The desired volume is detected by a pressure sensor which stops the filling and releases the vacuum after the lid is tightened to a specific torque level. In one embodiment, an apparatus fills the package mechanically with the desired modified atmosphere to a controllable level of pressure. 
     In one embodiment and another separable aspect, the high pressure food package comprises a sealable container having a wide mouth cup and lid, the lid having on its surface a one-way valve through which gas may be injected into the container, and a foil liner or other membrane suitably designed so as to burst when internal pressure within the container exceeds a predetermined level. For example, the high pressure food package may comprise a lid having a one-way membrane type valve as well as a foil liner. In one embodiment, the foil liner is sealed to the rim of the cup whereafter gas may be injected into the container through the one-way valve. In one embodiment, a hand operated gas filling device may be used for injecting the gas into the sealed container (for example, through a one-way valve). 
     In another separable aspect of the invention, the high pressure food package comprises a sealable container having a wide mouth cup and lid, the lid having on its surface a single-use push-pin through which gas may be released from the container prior to opening. 
     In another embodiment and another separable aspect, a lid can be designed as an ‘adapter’ that can be filled from existing standard soda bottle assembly lines but on the other side has the necessary wide-mouth for sealing and emptying large pieces of food (fruit and/or vegetables). 
     In one embodiment, the one-way valve is in the nature of a bicycle tire Schrader or Presta poppet type valve which could be used to inject CO2 or any modified atmosphere but also safely release it prior to opening the package. 
     Turning now to  FIG. 1 , a sectional side view of an exemplary high pressure food package and system is shown. It can be seen that one embodiment of the package system  100  includes a polyethylene terephthalate (PET or PETE) plastic wide mouth cup  102  and polypropylene (PP) lid  104  joined with four (12 pitch, 0.083″) interrupted threads  105  and a built in one or more point seal  106 ,  108 ,  110  inside the lid which comes into contact with the top rim  112  of the cup during tightening. Preferably, the rim  112  defines an opening into the cup  102  that is wide enough to allow finger access to chunks or pieces of non-liquid food product previously introduced into the cup  102 . Other materials may be used for the cup  102  and lid  104 , and the one or more point seal  106 ,  108 ,  110  may be formed integral to the cup  102  or lid  104  or may comprise separate components suitably fit to the cup  102  or lid  104  so as to provide a sealing function. As shown, seal  106  comprises a flap of material, annular in shape, formed integral to the lid  104 , and allows for gas to flow into the cup interior space  114  but prevents gas from flowing back out of the interior space  114  when the pressure in the space  114  exceeds an opposing pressure external to the cup  102  and lid  104  (and acting through the threads  104 ). The lid  104  may include a one or more point seal  108 ,  110  that engage with surfaces proximate to the rim  112  when the lid  104  is tightened downward upon the cup  102 . The threads  105  may or may not be interrupted type threads and may comprise other configurations in terms of pitch, size, and count. 
     A pressure chamber  116  is formed by collar housing  118 , support block  120 , bottom O-ring  124  and base plate  122 , which together hold the (as shown, partially closed) cup  102  and lid  104  assembly down by means of a vacuum  126  created in the pressure chamber  128  against the barrier of the cup and lid touching the upper  130  and lower O-rings  132 . 
     When the vacuum  126  is applied, the cup and lid assembly is held down while the desired gas  134  (e.g. CO2) is pumped into the package through the threads  105  apposing and joining the cup  102  and lid  104 . The detail view in  FIG. 1B  shows the path of the gas by the arrow  134 . As shown, a plug  136  may be used to block off additional access to the flow path  138  for the gas  134 . A flap of lid material  106  acts as a one-way valve allowing pressure to build within the interior space  114  of the package. When a desired internal pressure is detected, the pressurization stops and is removed, and the same flap  106 —due to its elasticity—acts to seal the pressure inside the package by way of its apposition against the cup rim  112 . The internal pressure itself acts to energize this seal  106 . 
     In various embodiments the package may comprise a screw lid which can hold pressure by means of an integral or separate pressure energized seal. The seal, such as the material flap  106  shown, is forced against the edge of the cup  102  and lid  104  (proximate to the rim  112 ) in such a way as to provide a very low torque required to open the cup and lid package. Other screw cap designs require a compression force between the lid/seal and cup/seal, but in the arrangement shown in  FIGS. 1A-1B  the material flap seal  106  provides a greater sealing force as the pressure is increased within the cup. The gas filling method may use a partially engaged seal and still allow pressure to build inside the cup because the differential pressure between the collar chamber and the package would flex the material flap seal  106  inward, creating a gas flow path  134 . An adhesive strip may be applied over the junction of the cup  102  and lid  104  to prevent inadvertent lid rotation and to provide indication of product tampering. 
     Several different embodiments of a pressure energized seal, using one or multiple points of contact between the lid  104  and the cup  102 , may be used. The seal may be integral (part of the lid  104 ) or separate (such as an O-ring) or applied as a different material coated onto the lid  104 . For example, the seal may be a soft but durable substance such as silicon sprayed onto the surface of the lid. Additional material might be added to the screw threads  105  (on either or both of the cooperatively sized threads on the lid  104  and cup  102 ) to assist in sealing. 
     Another embodiment may include curved fitted forms at the edge of the lid  104  and cup  102  as shown by example in  FIG. 7 , such that internal pressure inside the package holds the lid and cup together by means of the apposition of the forms, which fit together like two spoons. 
     In one embodiment, the lid  104  after package pressurization (i.e. after filling the package with gas) is tightened (to a specific torque) against the cup  102  by means of a torque wrench fitted to grab the lid using small fins protruding from the lid exterior surface for traction/grip. Preferably, opening the pressurized container (or depressurization) is accomplished by turning the lid to allow pressurized gas within the package to vent through the screw threads  105 . Re-tightening or re-sealing the lid  104  after opening the package may provide extended retention of the modified atmosphere in product remaining in the package. Preferrably, the re-sealed package is capable of retaining a positive internal pressure (as gas escapes from the food product and into the internal space  114  within the package or if additional gas is injected into the re-sealed package) so as to extend, maintain, or improve the effervescent character of the remaining product. 
     In one embodiment, PETE plastic may be used for one or both of the cup  102  and lid  104  and may be “oriented” such that overpressure first stretches and then rips longitudinally to prevent shrapnel. Preferably, materials used for the cup  102  and lid  104  comprise food-grade materials suitable for holding food product and are recyclable using currently available reclaiming/recycling methods. Preferably, the materials and designs used for the cup and lid package are such that the package is able to safely maintain internal pressures (measured as the differential pressure above ambient or external pressure, at sea level) of up to 90 psi so as to handle varied market conditions, for example, hot days, air travel, and dropping the package. More recently, polymers of plant sources which are biodegradable could also be engineered to meet these requirements. 
     In one embodiment, different colors of material may be used for one or both of the cup  102  and lid  104  to indicate the specific content of the package. For example, different colors may be used for particular types or combinations of fresh cut or minimally processed fruits or vegetables that may comprise the packaged product. As another example, a particular color may be used for packaged carbonated fresh fruit, and a different color may be used where the non-liquid food product comprises high viscosity sauces or smoothies. 
     Now referring to  FIG. 2 , an exemplary schematic for a pneumatic system for use with the high pressure food package and system of  FIG. 1A  is provided. 
     In one embodiment, the package system  100  may be controlled by a series of valves and switches so that the simple action of dropping a partially closed cup and lid assembly into the housing  118  while pressing a foot switch results in a sequence of events that holds the package down by vacuum, pressurizes the internal space  114  of the package through the threads  105  and one-way or material flap seal  106 , allows for tightening of the lid  104  to the cup  102 , and then releases the pressurized package by reversing the vacuum  126  underneath the package to a positive pressure which ejects the filled package. 
     In one embodiment, a foot switch (not shown) starts a vacuum pump VP, which when the vacuum is sufficient (determined using pressure gauge #3 PG3) to hold the cup down activates pressure switch #1 PS1 to open valve #5 V5, which begins filling the package with gas from a gas cylinder GC. When the desired internal package pressure is reached (e.g. 50 psi) and detected by gauge #2 PG2, pressure switch #2 PS2 activates five valves, valve #1 V1, valve #2 V2, valve #3 V3, valve #4 V4, and valve #6 V6, which cycle and reset the system as described. 
     When the pressure through the seal is discontinued, the remaining internal pressure inside the package energizes the seal  106  and maintains the internal pressure while the step of tightening the lid occurs. 
     The package is filled with a desired gas mixture to a preset pressure through the threaded lid during sealing, resulting—after equilibration of the gas into the product—in a desired level of effervescence in the product. If a scale is described from 1 to 5, where 1 is barely detectable effervescence, and 5 is visible and auditory effervescence (bubbles bursting from the product), the system preferably is capable of consistently reproducing any level of effervescence required in the product. The amount of effervescence is preferably made according to characteristics of the target consumer. For example, children might prefer more effervescence than adults. Younger consumers might prefer more effervescence in the product (e.g. an effervescence or Fizzy rating of approximately 4, or even higher at approximately 5) whereas older consumers might prefer less (e.g. an effervescence or Fizzy rating of approximately 3, or perhaps lower). 
     To achieve the desired effervescence and, therefore, the corresponding internal equilibrium pressures, the initial pressure is preferably greater than the subsequent equilibrium pressure in order to allow for the diffusion of gas into the product over time (e.g. a number of hours). The relationship of the initial to equilibrated pressure is a function of the mass of gas added and the headspace volume existing outside of the product within the package, according to the following equation: 
                     P   1     ⁢     V   1       -       P   2     ⁢     V   2             T   1     ⁢     T   2         =       (       n   1     -     n   2       )     ⁢   R           
Where,
         P 1 =The initial pressure inside cup   P 2 =The equilibrium pressure inside the cup   n 1 =Initial number of moles of CO2 in the headspace of the cup   n 2 =Number of moles of CO2 left in the head space after the absorption of CO2 into the fruit reaches equilibrium at a given pressure and temperature   n 1 -n 2 =The number of moles of CO2 that has been absorbed by the product; this depends on the amount of moisture inside the product and is relatively constant for a given product at a given temperature and pressure   R=Universal gas constant=8.3145 J/mol K   V 1  is the volume of cup after initial pressurization   V 2  is the volume after pressure reaches equilibrium. If the volume change of the cup under the pressure is negligible, i.e, V1=V2=V   T 1  is the initial temperature inside the cup   T 2  is the temperature inside the cup after pressure equilibrium is reached       

     If the cup is stored under refrigerated conditions, assume T 1 =T 2 =T, then equation 1 becomes: 
     
       
         
           
             
               
                 
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                       P 
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                       P 
                       2 
                     
                   
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                 ⁢ 
                 V 
               
               T 
             
             = 
             
               
                 ( 
                 
                   
                     n 
                     1 
                   
                   - 
                   
                     n 
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               R 
             
           
         
       
     
     However, for a given volume of product inside a cup, if you increase the headspace or the volume of the cup, V 1 , it will increase the initial number of moles of CO2, i.e., n 1  or the mass of CO2 inside the cup. In this way one can increase the fizziness level using the same initial pressure. 
     Turning now to  FIG. 3A , a cut side view of an exemplary high pressure food package that involves an overpressure feature is provided. In one embodiment, CO2 to pressurize the package  400  and generate the desired effervescence is forced through a nipple  402  in the center of the plastic cap  404  through a one-way membrane valve  406  covering a central hole in a foil induction seal liner  408  that has been electrothermally welded to the edge or rim  410  of the plastic bottle  412 . A production method for such package may comprise of first filling an interior space  414  of the bottle  412  with a quantity of food product, then torquing the cap  404  including the foil liner  408  and one-way valve  406  onto the cup or bottle  412  at a predetermined force, putting the cap  404  and bottle  412  through a device to electrothermally weld the foil liner  408  to the cup edge  410  thus creating the seal, and finally filling the package  400  with CO2 gas through the nipple  402  on the cap  404 . The cap  404  is preferably torqued to the bottle at a predetermined force that is low enough for easy hand removal of the cap (i.e. for use by children). The foil liner  408  provides an overpressure safety feature. If the internal pressure within the package exceeds a predetermined threshold, for example due to excessive heating of the pressurized package, the foil liner  408  is preferably designed to burst, typically near the rim  410 , or separate slightly from the rim  410  thereby releasing pressure from within the package. Other materials, such as a membrane liner or a plastic film, may be used for the overpressure safety feature, and such materials may be applied using a process other than an electrothermal (i.e. induction or radio frequency (RF) heating) process to seal the material to the rim  410 . 
     In various embodiments, the bottle  412  may comprise a cup  102  as in  FIG. 1A  or share one or more of the characteristics of the cup  102  previously described. Likewise, the cup  102  in  FIG. 1A  may comprise one or more of the characteristics of the bottle (or cup)  412  as in  FIG. 3A . Similarly, the lid  104  in  FIG. 1A  and the cap (or lid)  404  in  FIG. 3A  may share one or more characteristics. For example, in one embodiment, the bottle  412  comprises threads  416  which cooperatively mate with threads  418  formed on the cap  404 . However, as shown in  FIG. 3A , the cooperatively mating threads  416 ,  418  are shaped differently than the threads  105  shown in  FIG. 1A . Other thread shapes may be used. 
       FIG. 3B  is a cut bottom view of the lid portion of the high pressure food package of  FIG. 3A . As viewed from the bottom of the lid (or cap)  404 , according to a preferred embodiment, a one-way membrane valve  406  is centered about the nipple  402  so that an opening  440  in the nipple is aligned with an opening  426  in the foil liner  408  and an opening  424  in the membrane valve  406 . Gas injected into the nipple opening  440  passes through the foil liner opening  426 , into the membrane valve opening  424 , and the channel  420  between channel sides  422 ,  423  before beginning to fill the interior space  414  of the package  400 . Preferably, the foil liner opening  426  has a dimension (or diameter)  432  that is at least as large as the dimension  442  of the nipple opening  440 . Preferably, the valve opening  424  has a dimension  430  at least as large as the dimension  432  of the foil liner opening  426 . In one embodiment, the membrane valve  406  comprises a channel  420  between channel sides  422 ,  423  having a width dimension  428  that is larger than the valve opening dimension  430  so that membrane material in the bottom layer  438  is able to flex upward (as internal pressure within the interior space  414  of the package builds) to seal the channel  420  and the valve opening  424 . 
       FIG. 3C  is a detail sectional view of the one-way valve region of the high pressure food package of  FIG. 3A  showing in greater detail the foil liner  408  with one-way membrane valve  406  loaded into the lid (cap)  404 , according to one embodiment.  FIG. 3C  shows more clearly the layers comprising the valve and liner, in one embodiment. The component layers, from top to bottom, of the plastic cap  404  with a central nipple  402 , an induction seal foil liner  408 , and a one-way valve  406 , which itself consists of three membrane layers  434 ,  422 / 423 ,  438 . A channel in the middle layer  422 / 423  of the one-way valve  406  is forced open slightly by positive pressure applied from the nipple opening  440  and directed toward the center of the valve  406  to allow gas to flow in one direction, in this case, into the bottle  412 . Back pressure on the bottom layer  438  of the one-way valve  406  collapses at least the bottom layer  438  to prevent back flow of gas out of the bottle  412  and nipple  402 . In one embodiment, a small amount of viscous fluid, such as, for example, a drop of food-grade oil, may be placed in the valve opening  424  (which may then migrate into the channel  420 ) to help seal the channel  420  as back pressure deflects the bottom layer  438  to close the one-way valve. 
     The induction seal foil liner  408  may comprise a foil liner material coated on one side with a plastic material that heats when passed through the induction (or RF) energy field associated with induction sealing processes. The heated plastic coating then adheres to the surface in contact with the coating. Preferably, the plastic coating is oriented so as to adhere to the rim  410  of the bottle  412 , and the foil liner  408  or the weld joint between the rim  410  and foil liner  408  is suitably designed so as to fail at a predetermined pressure. For example, the foil liner  408  may be designed to fail at 90 psi internal pressure. Preferably, the foil liner  408  is suitably designed so as to burst (or develop a leak at the weld joint with the rim  410 ) as the lid  404  of the package  400  is twisted off/open. In a preferred embodiment, as the lid  404  is opened, the seal fails and begins to release pressure. Once the lid  404  is removed, the foil liner  408  remains on the edge/rim  410  of the bottle  412  and may be peeled off by pulling back a tab of liner material that extends just beyond the edge/rim  410  of the bottle  412 . 
     The present inventors discovered that if the foil liner seal weld is too strong, the seal may not fail soon enough when the cap is removed, resulting in a “pop” as the seal bursts abruptly. In a preferred embodiment, the strength of the weld between the foil liner  408  and the edge of the cup  410  is controlled such that the seal it creates is the weak link in the pressure integrity of the package. That is, the foil liner  408  detaches from the edge  410  of the cup  412  when the internal pressure reaches a predetermined value, e.g. 90 psi. At this point the package can no longer hold excess internal pressure and becomes incapable of preserving the effervescent effect. This safety feature addresses situations when a package may be thermally abused by a consumer resulting in internal fermentation of the food. Instead of excess pressure potentially bursting the package in uncontrolled or undesirable ways, the liner seal material is suitably designed to fail first and thereby allow pressure to escape through the threads between the cup  412  and lid  404 . 
     In one embodiment, after initial removal of the lid  404  from the pressurized package  400 , the foil seal will have been broken but may be kept in place (e.g. by only partially peeling back the foil liner  408 ) so that re-closing the lid  404  over the bottle  412  once again provides a package capable of retaining internal pressure. Additional CO2 may be injected into the package  400  to further extend the effervescence desired, for example, to maintain a higher fizziness level for the food product contained in the package (i.e. double inflation). 
     In one embodiment (as shown in  FIG. 4A ), a central plastic pin  542 , covered (such as by a breakaway, perimeter perforated membrane, not shown) to prevent tampering prior to opening, is found in the central area of the lid. To depressurize the package prior to opening, the pin cap  530  is depressed which punctures the seal  520  and releases internal pressure through the rent created by the pin in the seal. The structure of the plastic pin housing  502  prevents the pin from being removed from the lid, only allowing for downward movement. In one embodiment, when you press the piercing element through the membrane liner and continue pressing the element downward, the diameter of the piercing element tapers/increases such that the piercing element (pin  542 ) eventually blocks the opening having sides  516 ,  518 . In one embodiment this provides a resealing function, with subsequent excess pressure causing element/pin  542  to become unseated, lifting upward thereby allowing a further release of pressure. The high pressure food package may comprise a plastic cup and screw-on type threaded lid within which a quantity of product, such as a portion or a serving of fresh-cut fruits or vegetables, may be retained in a modified atmosphere (comprising, in part, pressurized carbon dioxide). In one embodiment, a foil liner in the lid is induction sealed to the rim of the cup to maintain the desired pressure. In one embodiment, a pre-determined amount of solid or liquid CO2 is placed into the container with the product just prior to sealing in order to sublimate into the volume and pressure of modified atmosphere desired. 
     In one embodiment, ribs  501  extend radially outward from pin housing  502  to ridge  510 . Detail view  500  provides an exemplary pin cap  530  structure comprising a downward extending pin  543  held in an upward, undepressed position above narrowing material  512  of the pin housing  502  and just below narrowing material  506  formed at an upper border  504  of the pin housing  502 . The pin housing  502  is shown circular in shape, with an outside diameter  534 , although other non-circular shapes may be used (as well as non-circular shapes for the pin cap  530  and other associated structure. The pin cap  530  is shown retained between the diameter  546  of the upper narrowing material  506  and the diameter  528  of the lower narrowing material  512 . The pin cap  530  is shown having a diameter  544  slightly wider than the diameter  528  at the narrowing material  512  region and slidably sized for downward travel to close space  514  when depressed. As the pin cap  530  is depressed so as to travel downward through a channel with sides  536  having a diameter  532 , the pin cap  530  moves from its normal undepressed position  508  between the upper  506  and lower  512  narrowing material. As the tip  522  of the pin  542  travels downward and pierces seal  520 , an opening in the seal  520  at  524 , in one embodiment, provides a path for the release of pressure from the downward side of the seal  524  between sides  516 ,  518  of a hole having a diameter  526 . In one embodiment, the pin  542  is tapered so as to eventually block the opening diameter  526  as the pin cap  530  is depressed downward. In one embodiment, continued depression of the pin cap  530  at least partially reseal the cup until excess pressure causes upward movement of the tapered pin  542  and subsequent release of pressure. 
     In one embodiment (as shown in  FIG. 4B ), the lid  554  of the package converges on a threaded bottle shape  552  identical to standard plastic soda bottles, making it possible for existing filling equipment to be used in production. The pieces of fruit or food product are first filled into the package, the wide portion of the lid  556  then screwed in place with an adequate U or 3-point seal, and then the package filled with gas or liquid CO2 using existing automated collar equipment to pressurize and carbonate the product. 
       FIG. 4C  shows another embodiment which utilizes existing one-way valve technology, so called ‘poppet’ valves  562 , which are embedded into the lid  564  and provide for both inflation and depressurization of the package through the same valve. 
       FIG. 5  illustrates basic principles of a retail carbonating package and the pressure profiles during different steps. In one embodiment, dry ice snow or pellets are added to the package which is immediately sealed, and the initial internal pressures approach 100 psi and gradually equilibrates over several hours into the fruit by diffusion to an equlibrium pressure of about 40 psi. (Red/solid line) This stable pressure produces a product which on opening is rated about a “Fizzy 4” on the Fizzy Scale of 1-5 (where “1” is barely detectable effervescence and “5” is audible and visual bubbles and very strong effervescence). The dotted line illustrates a package with less head space, where the initial loading pressure is similar but because less total CO2 is added, the final carbonation is lower (−15 psi or “Fizzy 1”). The other curve (blue/dash-dot) represents a package with internal chemical production of CO2 like the “Fizzolator” (U.S. Ser. Nos. 12/271,797, 11/548,212) used in school lunch programs. Once the package is opened (far right curve shown in  FIG. 5 ), a typical depressurization and loss of fizz occurs over about one hour, depending on fruit, temperature, and other factors. The pressure required to achieve a desired level of effervescence is a function of head space volume and time as described above. In one embodiment, the fill pressure is about 90 psi, which equilibrates after the food absorbs the CO2 gas to a final pressure of about 40 psi. A hand device may be used to inject the gas (e.g. CO2 or a CO2-O2 mixture) into each package through its nipple or one-way valve (ref. U.S. Ser. No. 11/943,964). The hand device preferably is suspended by a retractable mechanism and includes pressure sensors or switches for automatically stopping the flow of additional gas when the internal pressure of the package reaches a predetermined level (e.g. about 90 psi). 
     In one embodiment, a Fizzy rating of 4, indicating presence in the food product of easily detectable effervescence characterized by audible and visible bubbles, is a target minimum effervescence level for a particular consumer preference for said food product, and a Fizzy rating of 3, indicating presence in the food product of less easily detectable effervescence characterized by effervescence easily detectable at least by taste, is a target minimum effervescence level for a different particular consumer preference for the food product. In one embodiment, a Fizzy rating (or effervescence rating) of 3 represents a food product with effervescence that is easily detectable by the consumer&#39;s sense of taste, and a Fizzy rating of 4 represents a food product with more effervescence, effervescence that is easily detectable by the consumer&#39;s senses of vision (i.e. visual bubbles in the food product) and hearing (i.e. audible bubbles) in addition to the consumer&#39;s sense of taste (i.e. sensing the bubbles in the food product by taste). The Fizzy or effervescence rating for the food product is preferably chosen for a particular target consumer. For example, younger consumers may desire a food product such as apples or grapes with a higher level of effervescence than older consumers, or consumers in different geographic regions may prefer differing levels of effervescence. 
     Preferably, the cup  102  (or  412 ) may be sized for one, two, or three servings. In one embodiment, a single serving size is in the range of 2 oz to 3 oz. In one embodiment, a single serving package has a cup size of 2.6 oz (75 grams). One, two, or three servings may correspond with 2 oz, 4 oz, and 6 oz cup sizes, respectively. Cup sizes for one, two, or three services may correspond with cup sizes within ranges of 2-2.6 oz, 4-5.2 oz, and 6-7.8 oz, respectively. Other serving sizes, corresponding cup sizes, and ranges of cup sizes may be used. Preferably, the package is portable by hand and capable of being held in one hand. 
       FIG. 6  describes a thorough but by no means exhaustive illustration of the various embodiments and combinations that can be used to create a high pressure retail food carbonation package system. The figure is a concept map of the explored variables and design factors. These include the actual package material and structure design, the source of food product and its treatment prior to filling, the filling parameters of the head space, the source of CO2, the type of seal used and whether or not a valve is used, the shipping and storage considerations (greatly influenced by food type), and the depressurizing and opening mechanism. Many possible combinations will result in a successful outcome, but the scalability and costs of each system vary greatly. Each of the separable aspects may be mixed and matched in various different embodiments. For example, in one embodiment (starred items in  FIG. 6 ) a PETE cup and lid are filled with shelf-stable thermally treated fruit, and CO2 in the form of dry ice snow is used to manually fill, seal, and pressurize the package with CO2 using an induction seal, while a puncture pin (as in  FIG. 4A ) is used by the consumer to depressurize the package prior to opening by unscrewing the lid. 
       FIG. 7  shows an embodiment having a lid A with a rim gripping seal and pressure releasing pull-tab  2 . The lid A fits into a rim of a cup B where positive pressure within the cup B helps strengthen the seal between the cup B and lid A. The opening is a tab  2  built into the lid A which rips open the material (e.g. plastic) of the lid A to depressurize the cup B when it is time to open the package. The package (i.e. cup B and lid A) may be pressurized with an internal chemical reaction, dry ice, or pressurized through a one-way valve as described herein for other embodiments. As shown in  FIG. 7 , a deformable internal pressure indicator  1  is included to indicate sufficient internal pressure (e.g. indicator deflecting/deformed in an upward (convex) direction, away from cup B) or insufficient internal pressure (e.g. indicator in a concave, deflected downward direction). Pull-tab  2  is shown with a pull-tab-to-lid interface  3 . In one embodiment, pressure release/scored region  6  in the underside of the lid A provides a weakened area to allow outward movement of the pull-tab  2  to rip open the lid material. Also shown is, in one embodiment, shoulder material (tamper-proof wrapping)  4  and container body/labeling  5 . 
     In addition to the aforementioned embodiments, a type of modified “aerosol can” type package (not shown) may be used whereby product is stored in a can that looks like an aerosol can made of metal or plastic, where the base of the package is where the product is filled by the producer of the product, and sealed, and also where the consumer safely opens the product to retrieve and consume the product after depressing an aerosol button/valve assembly at the opposite side of the package. An advantage of this type of package and method of its use is that one side of the package comprises mechanisms to fill and release gas safely into and from the package, and the other side of the package is used to seal in and retrieve the food product. 
     All patents and patent applications referenced herein by patent number and/or patent application serial number are hereby incorporated by reference in their entireties. 
     The terms and expressions which have been employed in the forgoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalence of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.