Abstract:
In one embodiment, a method of forming frozen ice cream pellets includes supplying an ice cream premix into a loading vessel; loading a loading cylinder with the ice cream premix from the loading vessel, the loading cylinder being connected to the loading vessel; applying a machine-controllable force to expel the ice cream premix from the loading cylinder as ice cream premix pellets; and exposing the ice cream premix pellets to a cryogenic fluid, thereby at least partially freezing the ice cream premix pellets.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60/809,902, filed May 31, 2006 and to U.S. Provisional Application No. 60/810,321, filed Jun. 2, 2006. The entire contents of each aforementioned application are incorporated herein by reference. 
     
     BACKGROUND 
       [0002]    Sales of frozen foodstuff have risen dramatically in recent years. In particular, ice cream and yogurt product in the form of pellets have become very popular. 
         [0003]    One method of forming the pellets involves delivering flavored liquid dairy composition to a feed tray and then dripping the composition into a freezing chamber. The feed tray includes a sieve plate having orifices formed therein. The liquid dairy composition passes through the sieve plate and forms pellets that fall into the freezing chamber. The falling pellets of liquid compositions freeze rapidly in the freezing chamber, thereby forming solid pellets of flavored ice cream or yogurt product. The frozen pellets are removed from the freezing chamber and packed for distribution and later consumption. 
         [0004]    One problem encountered with the drip system is the production of pellets having different sizes. The non-uniform sized pellets detract from the appearance of the product. Additionally, the drip system also causes the pellets to drip at different times, thereby causing poor “belt loading.” Poor belt loading occurs when an insufficient quantity of pellets land in the cooling medium at any one time. Poor belt loading results in an inefficient use of the cooling medium, because more cooling medium will be required to freeze the same quantity of pellets. 
         [0005]    There is, therefore, a need for methods and apparatus for the production of pellets for frozen foodstuff. There is also a need for methods and apparatus for producing frozen food pellets of uniform size. 
       SUMMARY 
       [0006]    Embodiments of the present invention relate to methods and apparatus for producing frozen pellets of a foodstuff, in particular, pellets of an ice cream premix. In one embodiment, an injector apparatus is adapted to release pellets of the ice cream premix into a cooling medium. 
         [0007]    In one embodiment, a method of forming a frozen foodstuff pellet includes supplying a foodstuff premix into a loading vessel; loading a loading cylinder with the foodstuff premix from the loading vessel, the loading cylinder being connected to the loading vessel; applying a force to expel the foodstuff premix from the loading cylinder; and exposing the foodstuff premix to a cryogenic fluid, thereby at least partially freezing the foodstuff premix. 
         [0008]    In another embodiment, a method of forming frozen ice cream pellets includes supplying an ice cream premix into a loading vessel; loading a loading cylinder with the ice cream premix from the loading vessel, the loading cylinder being connected to the loading vessel; applying a machine-controllable force to expel the ice cream premix from the loading cylinder as ice cream premix pellets; and exposing the ice cream premix pellets to a cryogenic fluid, thereby at least partially freezing the ice cream premix pellets. In another embodiment, applying the machine-controllable force comprises injecting pressurized air into the loading vessel. In yet another embodiment, applying the machine-controllable force comprises injecting ice cream premix under pressure into the loading vessel. 
         [0009]    In another embodiment, a method of forming frozen ice cream pellets includes operating a reciprocating piston to supply ice cream premix into a loading vessel; depositing the ice cream premix from the loading vessel into a transport apparatus containing a cooling medium; and at least partially freezing the ice cream premix into pellets while transporting the ice cream away from the loading vessel. 
         [0010]    In yet another embodiment, an apparatus for forming frozen ice cream pellets includes an injector apparatus for depositing ice cream pellets and a cooling medium for at least partially freezing the ice cream pellets. In one embodiment, the injector apparatus may include a loading vessel and a reciprocating piston apparatus for supplying ice cream premix to the loading vessel. In another embodiment, the injector apparatus may include a loading vessel; a loading cylinder connected to a lower portion of the loading vessel and configured to deposit the ice cream pellets; and a pressurized source connected to the loading vessel for supplying fluid pressure to the loading vessel. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein: 
           [0012]      FIG. 1  illustrates an embodiment of a pelletizer assembly for producing frozen pellets of foodstuff; 
           [0013]      FIG. 2  illustrates another embodiment of a pelletizer assembly; 
           [0014]      FIG. 3  illustrates another embodiment of a pelletizer assembly; 
           [0015]      FIG. 4  illustrates an embodiment of an injector apparatus for use with a pelletizer assembly; 
           [0016]      FIG. 4A  illustrates an exploded view of a loading cylinder; 
           [0017]      FIG. 5  illustrates another embodiment of a pelletizer assembly; 
           [0018]      FIG. 6  illustrates another embodiment of a pelletizer assembly; and 
           [0019]      FIG. 7  illustrates an embodiment of a pump controlled depositing apparatus. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    Embodiments of the present invention relate to methods and apparatus for producing frozen pellets of a foodstuff, in particular, pellets of an ice cream premix. In one embodiment, an injector apparatus is adapted to release pellets of the ice cream premix into a cooling medium. 
         [0021]      FIG. 1  shows a pelletizer assembly  100  according to one embodiment of the present invention. The assembly  100  includes a storage tank  110  for a cooling medium  117 , preferably liquid nitrogen, and a pump  115  for pumping the cooling medium  117  to a trough  125 . The trough  125  may be horizontally positioned at a downward angle such that the cooling medium  117  may flow down toward a conveyor belt  135 . An outlet of an injector apparatus  130  is located above the upper end of the trough  125  for delivering foodstuff pellets  132  into the trough  125  and the cooling medium  117 . The length of the trough  125  is dimensioned such that sufficient time is provided for the cooling medium  117  to at least freeze the outer surface of the pellets  132 . Thus, the core of the pellets  132  may still be liquid when the pellets  132  reach the end of the trough  125 . The conveyor belt  135  is located below the trough  125  to collect the at least partially frozen pellets  132 . The conveyor belt  135  is adapted to collect the pellets  132  on the conveyor belt  135  but allow the cooling medium  117  to pass through. An exemplary material for the conveyor belt  135  is a metal screen. The cooling medium  117  is collected by a fluid collection apparatus  119  and returned to the storage tank  110 . In another embodiment, the length of the trough  125  may be selected to ensure that the pellets  132  are completely frozen by the time the pellets  132  reach the end of the trough  125 . In another embodiment, the cooling medium may be any suitable cryogenic fluid known to a person of ordinary skill in the art. 
         [0022]    The pellet freezing process in the trough  125  vaporizes some of the cooling medium  117  to produce a vaporized cooling medium  118 . The trough  125  and the conveyor belt  135  may be encased by a heat-insulating casing  140  in such a way that the vaporized cooling medium  118  are drawn off above the conveyor belt  135  in parallel flow with the transport direction of the pellets  132 . In one embodiment, the vaporized cooling medium  118  is drawn off by an exhaust-gas fan  145  installed above the end of the conveyor belt  135 . In this respect, the direction of flow of the gaseous cooling medium  118  corresponds to the transport direction of the pellets  132  on the conveyor belt  135 . Thus, the flow of gaseous cooling medium  118  may continue to remove energy from the pellets  132  during transport on the conveyor belt  135 . The length and speed of the conveyor belt  135  and the flow conditions of the vaporized cooling medium  118  may be selected in such a way that the pellets  132  are completely frozen by the time it reaches the end of the conveyor belt  135 . The frozen pellets  132  are collected in the container  150 . 
         [0023]    In another embodiment, the conveyor belt  135  may be arranged in line with, in the opposite direction of, or crosswise the direction of the trough  125 . In one arrangement, the trough  125  may be divided into a plurality of shorter troughs  225  on which the cooling medium flow and pellets  232  may flow forwards and backwards, as shown in  FIG. 2 . The divided trough  225  is beneficial for a space-saving type of construction. In a crosswise arrangement, a plurality of troughs  225  may feed directly to one conveyor belt  235  as illustrated in  FIG. 3 . 
         [0024]      FIG. 4  shows an embodiment of an injector apparatus  130  suitable for use with the pelletizer assembly  100 . The injector apparatus  130  includes a loading vessel  410  having a bottom wall with multiple holes  415  in fluid communication with a respective loading cylinder  420 . In the embodiment shown in  FIG. 4 , the injector apparatus  130  includes a large rectangular loading vessel  410  having dimensions of at least about 30″ L×6″ W×18″ H. The bottom wall of the loading vessel  410  has multiple, uniformly aligned holes  415  that are positioned as closely as possible in proximity to each other. In one embodiment, each hole  415  is approximately 0.5″ in diameter. It must be noted that the holes  415  may be positioned in any suitable manner, for example, evenly spaced apart, random, aligned diagonally, vertically, or horizontally, or combinations thereof. 
         [0025]    Each hole  415  may be fitted with a small diameter loading cylinder  420 . In one embodiment, the loading cylinders  420  are positioned above an opening in the pelletizer  100  such that the pellets  132  expelled from the loading cylinders  420  may land in the cooling medium  117  flowing in the trough  125 . Referring to  FIG. 4A , the loading cylinder  420  may have an enlarged, beveled opening at the top to facilitate connection to the respective hole  415  in the loading vessel  410 . Exemplary forms of the loading cylinder  420  include a short nozzle, a long tube, or any form suitable for delivering the pellets  132 . The diameter of the loading cylinder  420  may be sized to prevent the ice cream premix to drip from the loading cylinder  420  due to gravity alone. In one embodiment, the loading cylinder  420  is sized between about 2-5 mm ID and about 50-150 mm long. In another embodiment, the loading cylinder  420  may be sized between about 1-10 mm ID and about 10-250 mm long. A stabilizing support plate  430  may be connected to the lower end of the cylinders  420  to stabilize and maintain the alignment of the loading cylinders  420  with respect to the loading vessel  410 . 
         [0026]    A hole  433  may be provided at the top of the loading vessel  410  to allow ice cream premix to be pumped into the loading vessel  410 . A loading tube  435  may be connected to the hole  433  to supply the ice cream premix to the loading vessel  410 . In one embodiment, the tube  435  supplies the ice cream premix in an airtight manner. A check valve  437  (or other forms of one way valve) may be installed on the loading tube  435  to prevent the ice cream premix to flow backwards. The ice cream premix may be pumped from flavor tanks or other premix storage vessels into the rectangular loading vessel  410 . In one embodiment, the ice cream premix is maintained at a level between about 15% to 95%; preferably, about 50% to 80%, of the loading vessel  410 . In another embodiment, the ice cream premix is maintained at a level sufficient to maintain a proper head pressure above the loading cylinder  420  such that the desired size of pellets  132  is ejected. 
         [0027]    High pressure air, nitrogen, carbon dioxide vapor, or other compressed gas may be supplied into the headspace above the ice cream premix in the loading vessel  410 . As shown in  FIG. 4 , a compressed gas line  440  is connected to the loading cylinder  410  to supply gas as needed. The flow of compressed gas may be controlled through the use of a timer-operated on/off solenoid valve  447 . 
         [0028]    In operation, the ice cream premix is supplied into the loading vessel  410  using the loading tube  435 . The premix may flow into the top portion of each loading cylinder  420  and may partially flow down the loading cylinder  420 . The viscosity of the premix, coupled with the length and the restricted inner diameter of the cylinder  420 , may restrict the ability of the premix to flow smoothly through the cylinder  420 , thereby blocking the cylinder  420  with the liquid premix. At this point, each cylinder  420  is considered “loaded”. The premix may continue to be supplied until a predetermined level of premix in the loading vessel  410  is reached. 
         [0029]    The compressed gas may then be injected into the empty headspace of the loading vessel  410 . The increase in pressure in vessel  410  forces some of the premix down and out of the cylinder  420 , thereby depositing a volume of premix pellets  132  into the liquid nitrogen stream  117  and trough  125  below. The desired size of premix pellets  132  to be deposited may be controlled by managing the quantity of compressed air injected into the loading vessel  410 . The next batch of pellets  132  may be deposited as soon as the previous batch clears the path of the loading cylinders  420 . In this manner, the pellets  132  may be deposited into the liquid nitrogen  117  in the same accurate pattern and volume with each actuation of the compressed gas. 
         [0030]    The continuous stream of liquid nitrogen  117  carries away the deposited premix pellets  132 . The liquid nitrogen  117  at least partially freezes the pellets  132 . The trough  125  delivers the pellets  132  and the liquid nitrogen  117  to the conveyor belt  135 , where the separated pellets are retained, while the liquid nitrogen  117  is recycled back to the storage tank  110 . On the conveyor belt  135 , the pellets  132  continue to solidify until it is completely frozen. At the end of the conveyor belt  135 , the frozen pellets  132  are collected in the container  150 . In this manner, an almost seamless, continuous flow of ice cream premix pellets  132  may be applied in a very tight pattern without danger of excessive mating or freezing together. 
         [0031]    In another embodiment, the injector apparatus  130  may positioned on a load cell  460  or other suitable load measuring device, as shown in  FIG. 1 . The load cell  460  may be adapted to measure the load on the injector apparatus  130  which is correlated to the level of premix in the loading vessel  410 . As the premix is forced out of the rectangular loading vessel  410 , the load cells  460  supporting the loading vessel  410  may monitor volume of premix remaining in the loading vessel  410 . When the level of the premix reaches a preset lower limit, the premix pump may be activated to load premix into the loading vessel  410  through the loading tube  435 . The premix loading may continue until the load cells  460  register a preset upper limit. This cycle may be repeated to maintain the premix volume in a steady range. The steady premix range provides a constant head pressure on the loading cylinders  120 , thereby assuring accurate deposition of the pellets  132 . In another embodiment, the injector apparatus may be equipped with a sensor to measure the height of the premix in the loading vessel  410 . The quantity of premix may be controlled based on the level of the premix measured by the sensor. 
         [0032]    Advantages of one embodiment of this system include dramatically improved coverage of ice cream premix pellets in the liquid nitrogen, substantially increased production rates, highly consistent pellet size, ability to vary pellet size through pressure, duration of compressed gas cycle, and reduced incidence of product mating. 
         [0033]      FIG. 5  illustrates a side view of another embodiment of a pelletizer assembly  300 . As shown, the trough  325  is provided with a barrier  350  disposed at the downstream end and an opening  355  for the pellets  332  to leave the trough  325 . In one embodiment, the barrier  350  is configured to retain the pellets  332 , but allow the cooling medium  317  to pass. Exemplary barriers include a metal or non-metal structure having a plurality of apertures or perforations such as a metal screen, a multilayer screen, and any other suitable porous structure. The opening  355  may be a slot or other apertures formed on the trough  325  and/or between the trough  325  and the barrier  350  and sufficiently sized for the pellets  332  to pass. In use, the injector apparatus  330  deposits the pellets  332  in the trough  325 , where they are cooled by the cooling medium  317 . The cooling medium  317  carries the pellets  332  toward the end of the trough  325  where the pellets  332  fall through the opening  355  and land on the conveyor belt  335  or other collection apparatus. The barrier  350  retains the pellets  332  in the trough  325  until they fall through the opening  355 . A portion of the cooling medium  317  passes through the opening  355  along with the pellets  332 , while the remaining portion continues through the barrier  350  and falls on the conveyor belt  335  at a point downstream of the opening  355 . In this respect, the cooling medium  317  cascades on top of the pellets  332  that have accumulated on the conveyor belt  335 . As a result, the at least partially frozen pellets  332  may receive another exposure to the cooling medium  317  while being carried by the conveyor belt  335  toward the collection container  150 . The additional exposure of the pellets  332  to the cooling medium  317  effectively increases the freezing capacity of the assembly  300 . In another embodiment, the barrier  350  may be a solid wall such that all of the cooling medium  317  and pellets  332  are forced through the opening  355 . 
         [0034]      FIG. 6  illustrates a top view of another embodiment of a pelletizer assembly  300 . The pelletizer assembly  300  includes a trough  325  having a pellet barrier  350 . As shown, the end of the trough  325  is angled relative to the direction of travel of the pellets  332 . In one embodiment, the end of the trough  325  is angled between about 30 degrees and 60 degrees, more preferably, between about 40 degrees and 50 degrees. The conveyor belt  335  is positioned at about a right angle relative to the trough  325  to collect the pellets  332  exiting the opening  355 . However, it is contemplated that the trough end may have any suitable angle, and the conveyor belt may be positioned at any angle capable of collecting the pellets. In use, the injector apparatus  330  deposits the pellets  332  in the trough  325 , where they are cooled and carried away by the cooling medium  317 . At the end of the trough  325 , the pellets  332  drop through the opening  355  and land on the conveyor belt  335  or other collection apparatus. The barrier  350  stops the pellets  332  in the trough  325  until they fall through the opening  355 . The angled end of the trough  325  allows the pellets  332  that fall through the opening  355  to spread across the width of the conveyor belt  335 . Some of the cooling medium  317  flows through the barrier  350  and drenches the pellets  332  accumulated on the conveyor belt  335 . As a result, the at least partially frozen pellets  332  may receive another exposure to the cooling medium  317  while being carried by the conveyor belt  335  toward the collection container  150 . 
         [0035]    In another embodiment, the injector apparatus  130  may utilize a pump controlled depositing apparatus  535  to deposit the pellets  132  into the liquid nitrogen  117 . In  FIG. 7 , the injector apparatus  130  in shown with a pump controlled depositing apparatus  535  for delivering ice cream premix to the loading vessel  410  and depositing pellets  132  into the liquid nitrogen  117 . As shown, the depositing apparatus  535  has an inlet end  510  connected to the premix source  505  and an outlet end  520  connected to the loading vessel  410 . A one way valve  512  is positioned at each end to control the flow of the premix. A loading chamber  530  is formed between the two valves  512 ,  522 . The inlet valve  512  at the inlet end  510  allows premix to enter the loading chamber  530 , but not leave. The outlet valve  522  at the outlet end  520  allows the premix to leave the loading chamber  530 , but not enter. In one embodiment, each valve  512 ,  522  is a ball valve having a ball biased by a biasing member such as a spring. It is contemplated that other suitable one way valves may be used. 
         [0036]    The reciprocating piston pump apparatus  535  is used to draw the premix into the loading chamber  530  and force the premix into the loading vessel  410 . In one embodiment, the piston pump  535  includes a fluid operated reciprocating piston  550  cooperating with a fluid cylinder  540 . The piston  550  includes a head  551  that forms a wall of the loading chamber  530 , whereby reciprocation of the head  551  changes the volume of the loading chamber  530 . The piston  550  also includes a tail  552  located in the fluid cylinder  540 . The injection of fluid in front of or behind the tail  552  causes the axial of the movement of the piston  551 . Fluid may injected into the fluid cylinder  552  via one of two fluid ports  541 ,  542  located at each end of the cylinder  540 . In another embodiment, piston may be reciprocated by an electric motor. 
         [0037]    In operation, the loading vessel  410  is initially full charged with the ice cream premix. Pressurized gas is supplied through the first port  541  in front of the tail  552  to cause the piston to move to the left, thereby increasing the volume of the loading chamber  530 . The loading chamber expansion causes the ice cream premix to be drawn through the inlet valve  512  to fill the loading chamber  530 . The ice cream premix in the loading vessel  410  cannot come back through the outlet valve  522  due to the one-way nature of the valve  522 . Thereafter, pressurized gas is supplied through the second port  542  behind the tail  552  of the piston  550  to cause the piston  550  to move toward the loading chamber  530 , thereby decreasing the volume of the loading chamber  530 . This reduction in volume forces the premix to exit the loading chamber  530  through the outlet valve  522 . The ice cream premix is not forced back into the premix source  505  due to the one way nature of the inlet valve  512 . Because the loading vessel  410  was fully charged, the newly injected premix displaces premix pellets  132  out from the bottom of the loading cylinder  420  and into the liquid nitrogen. The cycle may be repeated to deposit more ice cream premix pellets into the liquid nitrogen. 
         [0038]    It will be understood that many additional changes in the details, materials, steps, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above and/or the attached drawings.