Abstract:
An apparatus and method for continuous vacuum marination of a food product. A paddle assembly in a stationary vacuum chamber lifts and tumbles food product in a marinade. The paddles are formed into two subassemblies that are offset to smooth out the load on the paddles and the drive motor. The center about which the paddle assembly rotates is offset from the center of the vacuum chamber to avoid pinching and damaging the food product. The food product is introduced into the vacuum chamber periodically through an airlock type inlet assembly and removed by means of a similar airlock type outlet assembly. The outlet assembly includes an outlet chute for receiving the marinated food product. The outlet chute has a volume which is less than the volume of an internal chamber of the airlock outlet assembly so that closing the door to the outlet airlock door will not damage the food product. The food product is weighed into and out of the vacuum marinator. The rate of cycling of the output is controlled and adjusted based on the input and output weights to maintain a desired retention time of the food product in the vacuum chamber. The vacuum chamber is shaped with a bulge at the top to define a space to accommodate a spray for cleaning the paddles. Also, a cleanout hatch is provided to aid in cleaning the interior of the vacuum chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/937,681 filed Jun. 29, 2007, the disclosure of which is incorporated herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to a method and apparatus for continuous vacuum marination of a food product. 
         [0005]    2. Brief Description of the Related Art 
         [0006]    In the art of vacuum marination, it is known to employ batch processes where the food product, such as meat, to be marinated is placed into a vacuum chamber which is rotated for a set period of time after which the marinated food product is removed from the vacuum chamber. 
         [0007]    Continuous vacuum marinators are also known. For example, U.S. Pat. No. 6,007,418 to Suhner discloses a vacuum tumbler having an evacuatable drum mounted for rotation around its longitudinal axis. The drum is provided on one end with a loading opening and on the other end with a removal opening. For continuous operation, a vacuum sluice is arranged at both the loading opening and the removal opening. A vacuum packing, which is effective when the drum is rotating, is present between the openings and the corresponding vacuum sluice. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention is an apparatus and method for continuous vacuum marination of a food product. The vacuum chamber is stationary while a paddle assembly within the vacuum chamber lifts and tumbles the food product in the marinade. The paddles are formed into two subassemblies that are offset to smooth out the load on the paddles and the drive motor caused by the paddles lifting the food product. The center about which the paddle assembly rotates is offset from the center of the vacuum chamber to avoid pinching and damaging the food product as it is lifted into the outlet chute. 
         [0009]    The food product is introduced into the vacuum chamber periodically through an airlock type inlet assembly with a pair of sliding doors which open and close in sequence to avoid the loss of the vacuum. The marinated food product is removed from the vacuum chamber by means of a similar airlock type outlet assembly. The outlet assembly includes an outlet chute sized and located so that as the paddle lifts the marinated food product some will fall into the outlet chute. The outlet chute holds a quantity of marinated food product until it is periodically dumped through the airlock type outlet assembly. The outlet chute has a volume which is less than the volume of an internal chamber of the airlock outlet assembly so that when the first sliding door to the airlock opens to dump the accumulated marinated food product, there will be sufficient clearance to avoid having the sliding door damage the food product or be rendered inoperable by jamming. 
         [0010]    The food product is weighed into and out of the vacuum marinator. The rate of cycling of the output is controlled and adjusted based on the input and output weights to maintain a desired retention time of the food product in the vacuum chamber. 
         [0011]    The vacuum chamber is shaped with a bulge at the top to define a space that remains outside the volume swept by the paddles. This space accommodates a spray for cleaning the paddles. Also, a cleanout hatch is provided to aid in cleaning the interior of the vacuum chamber. 
         [0012]    These and other features, objects and advantages of the present invention will become better understood from a consideration of the following detailed description of the preferred embodiments and appended claims in conjunction with the drawings as described following. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of an embodiment of the apparatus for continuous vacuum marination of the present invention. The view is from the drive or inlet end. 
           [0014]      FIG. 2  is a perspective view of an embodiment of the apparatus for continuous vacuum marination of the present invention. The view is from the outlet end. 
           [0015]      FIG. 3  is a block diagram of an embodiment of the method for continuous vacuum marination of the present invention showing the inlet and outlet weighing steps. 
           [0016]      FIG. 4  is an elevation view of the outlet end of the vacuum chamber with the outlet end plate removed showing the paddle assembly. 
           [0017]      FIG. 5  is a perspective view of the offset paddle subassemblies. 
           [0018]      FIG. 6  is an elevation view of the outlet end of the apparatus showing the cleanout hatch. 
           [0019]      FIG. 7  is an elevation view of an alternative embodiment of the inlet assembly. 
           [0020]      FIG. 8  is an elevation view of an alternative embodiment of the outlet assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    With reference to  FIGS. 1 and 2 , the vacuum marinator  10  is mounted on a frame  11 . The vacuum marinator  10  has a shell  12  closed by inlet end plate  13  and outlet end plate  14  to form a vacuum tight internal chamber  30  for receiving and marinating food products in a marinade under vacuum conditions. The mechanism for maintaining the vacuum is not shown. Any of various means for maintaining a suitable vacuum would be known to those of ordinary skill in the art. A jacket (not shown) around the shell  12  may be provided for cooling. The drive end plate  13  has a drive motor  15  mounted thereon for driving a paddle assembly  40  as described more fully below. 
         [0022]    An inlet assembly  16 , comprising an inlet hopper  17 , an inlet inner chamber  18 , an inlet chute  19 , a first sliding gate  20  and a second sliding gate  21 , as shown in  FIGS. 1 ,  2 , and  4 , communicates with the internal chamber  30 . The inlet hopper  17  receives and guides the food product into the inlet assembly  16 . The first sliding gate  20  and the second sliding gate  21  define the entrance and exit, respectively, to the inlet inner chamber  18  and all together form an airlock entry to the internal chamber  30 . A quantity of food product, guided by the inlet hopper  17 , enters the inlet inner chamber  18  when the first sliding gate  20  is opened. The first sliding gate  20  is then closed before the second sliding gate  21  is opened to the vacuum conditions in the internal chamber  30 . The food product in the inlet inner chamber is then discharged into the internal chamber  30  through the inlet chute  19 . The motion of the paddle assembly  40  described hereinafter may be timed to avoid being in a position to slice or otherwise damage the food product as it is being discharged into the internal chamber  30 . 
         [0023]    Inside the internal chamber  30 , the food product is tumbled in a marinade for a predetermined retention period by a paddle assembly as shown in  FIGS. 4 and 5 . The paddle assembly  40  comprises a plurality of paddles  41  mounted on paddle supports  42  for rotation about a shaft  43 . The shaft  43  is operatively connected to the drive motor  15  for rotation of the paddle assembly  40 . It is preferable that the paddle assembly comprises two separate subassemblies of three paddles  41  each as shown in  FIG. 5 . The three paddles  41  of one subassembly are angularly offset from the three paddles  41  of the other subassembly as shown in the end view of  FIG. 4 . It will be appreciated that as the paddle assembly  40  is rotated, the food product is picked up and tumbled by each of the paddles  41  in turn. Each time a paddle  41  encounters a concentration of the food product, an increased load is placed on the paddle assembly  40  and in turn an increased load is placed on the drive motor  15 . Having the two subassemblies of angularly offset paddles  41 , this varying load is advantageously smoothed out. 
         [0024]    As illustrated by  FIG. 4 , the internal chamber  30  is preferably not cylindrical in shape. The cross section of the internal chamber  30  comprises a circular arc  50  of approximately 270° of a complete circular arc together with an outwardly bulged section  51 . The movement of the outward edges of the paddles  41  closely approximates to the circular arc  50 , while leaving a space  52  at the top of the internal chamber  30  that is defined by the outwardly bulged section  51 . The space  52  allows one or more sprays (not shown) to be mounted in the inside of the internal chamber  30 . By means of the sprays, a clean-in-place (CIP) regimen may be employed to clean the paddles  41 . For example, three sprays may desirably be disposed so as to allow cleaning of the full length of the paddles  41 . Alternatively, and less desirably, if the cross section of the internal chamber  30  is entirely circular, the two subassemblies of the paddles  41  may be separated by a space to accommodate a spray extending into the internal chamber  30  for cleaning the paddles  41 . As shown in  FIG. 6 , clean out of the internal chamber  30  may also be facilitated by a cleanout hatch  61  in the lower portion of the outlet end plate  14 . Alternatively, and less desirably, the entire outlet end plate  14  may be removed for cleaning. The space  52  also allows the inlet to the vacuum system to be located such that the food product and marinade is not sucked into the vacuum system. 
         [0025]    As the paddle assembly  40  is rotated within the internal chamber  30 , the food product is tumbled in the marinade. To exit the internal chamber  30 , an open exit chute  60  is placed on one side of the internal chamber  30  below a horizontal centerline. As the paddles  41  lift the food product, portions of the food product spill into the exit chute  60 . The exit chute  60  is part of the outlet assembly  25 . The outlet assembly  25  also comprises a first sliding gate  26  and a second sliding gate  27 . The first sliding gate  26  and the second sliding gate  27  define the entrance and exit, respectively, to an outlet inner chamber  28 , and all together form an airlock exit from the internal chamber  30 . A quantity of food product spilled into the outlet chute  60  by the rotating paddles  41  enters the outlet inner chamber  28  when the first sliding gate  26  is opened. The first sliding gate  26  is then closed before the second sliding gate  27  is opened to the atmosphere so that the food product in the outlet inner chamber  28  is discharged. The volume of the outlet chute  60  is less than the volume of the outlet inner chamber  28  so that there is no danger of the food product blocking the closing of the first sliding gate  26  and thereby being subjected to damage by the closing of the first sliding gate  26 . 
         [0026]    With further reference to  FIG. 4 , the center of the shaft  43  is preferably not located at the center of the circular arc  50 . It is desirable that the outermost edges of the paddles  41  closely approximate the walls of the internal chamber  30  at a point on the side opposite to the exit chute  60  and that all other points in the rotation of the paddle assembly  40 , the outermost edges of the paddles  41  should be slightly farther away from the walls of the internal chamber  30 . This is achieved by having the center of the shaft  43  mounted approximately ½ inch away from the center of the circular arc  50 . The center of the shaft  43  is displaced toward the point on the wall of the internal chamber  30  where the outermost edges of the paddles  41  most closely approach the wall of the internal chamber  30 . This point is defined by the angle a shown in  FIG. 4 . The angle a is preferably about 45° below a horizontal centerline pointed toward side of the vacuum marinator  10  opposite to where the exit chute  60  is located. This slight offset ensures that the outermost edges of the paddles  41  are closest to the wall of the internal chamber  30  where the paddles  41  first make contact with the food product and thereby the food product is less likely to be pinched and damaged throughout the remainder of the period of contact with the paddles  41 . Furthermore, by having the outermost edges of the paddles  41  spaced apart from the wall of the internal chamber  30  at all other points, there is less danger of the food product being pinched against the walls of the internal chamber  30 , for example at the point where the top of the exit chute  60  meets the wall of the internal chamber. 
         [0027]    The operation of the vacuum marinator  10  of the present invention may be described with reference to  FIG. 3 . An input stream of food product is transported to the vacuum marinator  10 , for example, by inlet conveyor  70 . The input stream is apportioned into a sequence of input batches. The input batches are weighed by an input weighing device  71 , which may be any type of weighing device known to those of ordinary skill in the art. Each of the input batches therefore are given an associated weight determined by the input weighing device  71 . Each input batch is charged sequentially into the internal chamber  30  through the input assembly  16  as described above. Marinade is charged into the internal chamber  30  based on a predetermined desired ratio of marinade to food product. 
         [0028]    The food product is tumbled in the marinade for a period of time, which is desirably a predetermined retention time. The output assembly  25  operates at a predetermined output cycle time. With each cycle of the output assembly  25 , a portion of the food product from the internal chamber  30  is discharged into output weighing device  72  to apportion the food product discharged from the internal chamber  30  as a sequence of output batches, each of the output batches having an associated weight determined by the output weighing device  72 . The output weighing device  72  may be any type of weighing device known to those of ordinary skill in the art. 
         [0029]    The predetermined output cycle time is then adjusted by a controller  73  based on an average of a sequence of input batch weights and an average of a sequence of output batch weights to maintain a given quantity of the food product in the internal chamber  30  for a predetermined retention time. The controller  73  may be any of various types of control devices known to those of ordinary skill in the art, such as a programmable logic controller (PLC). The following example is given to illustrate the operation of the present invention. 
         [0030]    Assume that the desired retention time for the food product in the vacuum marinator  10  is 40 minutes and that the vacuum marinator  10  is intended to hold 2000 pounds at any give time. This implies that at a steady state, the input and output rates for the food product would each be an identical 50 pounds per minute. One way of achieving these rates would be for each of the input and output batch weights to be exactly 50 pounds and the input and output cycle times to be 1 minute or 60 seconds each. However, the actual input and output batch weights will vary from the ideal figures. For example, if the input batch weights are 50 pounds each, but the output batch weights drop to 40 pounds each, the amount of food product in the vacuum marinator  10  would begin to rise and the retention time in the vacuum marinator  10  would increase beyond the desired 40 minutes. In order to maintain a steady state condition with 40 pounds of food product in each output batch, the output cycle time must be decreased from 60 seconds to 48 seconds to maintain the same rate of withdrawal of food product from the vacuum marinator  10 . If on the other hand, the output batch weight increases to 60 pounds, then the output cycle time must increase from 60 seconds to 72 seconds to maintain a steady state condition. 
         [0031]    In reality, both the input and the output batch weights will vary from batch to batch. In order to maintain a steady state condition with the desired retention time, the output cycle time must be constantly varied in response to the variation in the input and output batch weights. To smooth out these variations in input and output batch weights, it is desirable to adjust the output cycle time based on an average of a sequence of input and output batch weights. For example, an average of three consecutive batch weights has been found to be acceptable. 
         [0032]    The examples discussed above do not take into account the fact that marinade is added to the vacuum marinator  10  in proportion to the amount of food product introduced into the vacuum marinator  10 . For example, the amount of marinade might be set at 15% of the weight of the food product. If 2000 pounds of food product were introduced into the vacuum marinator  10 , then the total weight of food product and marinade maintained in the vacuum marinator  10  would be 2300 pounds. If the retention time is selected properly, the marinade will be totally absorbed into the food product during the 40 minute retention period. Therefore, if the input batch weight at a steady state condition is 50 pounds, then the steady state output batch weight would be 1.15×50 pounds or 57.5 pounds. The discussion above would then apply to output batch weights above or below this desired steady state level. 
         [0033]    An alternative embodiment of the inlet and outlet assemblies of the vacuum marinator  10  are described with referenced to  FIGS. 6 and 7 . The alternative embodiment of  FIGS. 6 and 7  improves the flow of product and also lowers the height of some of the equipment to make setup, maintenance, and clean-up easier. 
         [0034]    The alternative embodiment of the inlet assembly differs from the embodiment described above in that the series of slide gates on top of the vacuum marinator  10  is replaced by an inlet hopper  106  mounted lower on the vacuum marinator  10 . The inlet hopper  106  pulls product and marination into it by vacuum, weighs it, and then the product and marination mixture are pulled into the internal chamber  30  of the vacuum marinator  10  by vacuum. The alternative embodiment of the outlet assembly drops product through an upper slide gate  203  into a chamber  205 , and then applies pressure to the chamber  205  and opens a lower sliding gate  204  to push the product out of the chamber  205  through piping  210  to a weigh hopper  211  that is located over the belt  213  or other system that is being fed by the vacuum marinator  10 . 
         [0035]    With reference to  FIG. 6 , the inlet assembly includes a hopper  106 , two slide gate valves  110 ,  115 , inlet piping  102  connected by connection point  104  from an inlet hopper to the hopper  106  and outlet piping  101  from the hopper  106  to the internal chamber  30  of the vacuum marinator  10  through a connection point  105 . The inlet and outlet piping  102 ,  101  are mounted to pipe supports  109  at vertical sections and may be provided with flex hose sections  103 . The hopper  106  is provided with a ball valve  111  for marination, and a three-way ball valve  112  for the vacuum/vent operation. The hopper  106  is mounted on mounting brackets  108  via load cells  107  to determine the weight of the product inside it. The ball valves  111 ,  112  and gate valves  110 ,  115  are automatically actuated by controller  73  such as a programmable logic controller (PLC) to control the movement of product and marination through the system. 
         [0036]    The upper gate valve  110  is connected between the inlet piping  102  and the top of the hopper  106 . The hopper  106  is connected at the bottom through the lower gate valve  115  to the outlet piping  101 . The flex hose sections  103  isolate the hopper  106  from the vacuum marinator  10  and from the inlet hopper. The flex hose sections  103  also allow the vertical sections of the inlet and outlet piping  102 ,  101  to be supported on support brackets  109  to carry a portion of the weight of the piping and the weight inside it. 
         [0037]    To begin the inlet cycle, the upper gate valve  110  is opened, and the lower gate valve  115  is closed. The three way ball valve  112  is cycled to connect to the vacuum source  114  and the hopper  106  is placed under vacuum. Product then begins to flow from the inlet hopper through the inlet piping  102  to the hopper  106 . Once the system detects that the hopper  106  has the desired amount of product in it by sensing the weight, the three-way ball valve  112  is cycled back to vent to the atmosphere, so the vacuum in the hopper  106  is released, and the product stops entering the hopper  106 . After a delay to ensure there is no more product entering, the upper gate valve  110  is closed and the system records the weight of the product in the hopper  106 . Using this weight, the system calculates how much marination needs to be added based on the desired marination percentage. The marination ball valve  111  is then opened and the marination from the marination source  113  is pumped into the hopper  106  until the desired total weight is reached for the product plus the marination. Once this weight is reached, the marination ball valve  111  is closed and an accurate weight is be recorded. The error in the amount of marination added is recorded and offset to the next batch so the total throughout the day is accurate. After this, the lower gate valve  115  is opened, and since the internal chamber  30  of the vacuum marinator  10  is under vacuum and the hopper  106  is still vented to the atmosphere, the product is sucked from the hopper  106  into the internal chamber  301 . This cycle is repeated as often as necessary to keep up with the desired inlet rate. 
         [0038]    The outlet system includes upper and lower slide gate valves  203 ,  204  with a chamber  205  between them. The upper gate valve  203  is large so that product is easily dropped through it, and the lower gate valve  204  is smaller because product is pushed through it with air pressure. Above the upper gate valve  203  is an upper product chamber  202  connected to and open to the internal chamber  30  so that product from the internal chamber  30  falls into and rests on top of the gate in the upper gate valve  203  until it is opened. The upper product chamber  202  is smaller than the chamber  205  so that when the upper gate  203  opens, the product that falls through will not be enough to fill up the chamber  205  and will not get cut by the upper gate  203  when it closes again. The chamber  205  is operable connected to two three-way ball valves  206 ,  212 . By using the ball valves  206 ,  212 , the chamber  205  is attached via a pressure equalization line  209  to the internal chamber  30  of the vacuum marinator  10  in order to pull a vacuum on the chamber  205 , to an air pressure source  208 , or vented to the atmosphere  207 . A weigh hopper  211  at the end of the piping to weigh all product that comes out of the vacuum marinator  10 . 
         [0039]    To begin the outlet cycle, the ball valves  206 ,  212  are positioned to connect the chamber  205  to the internal chamber  30  of the vacuum marinator  10  so the pressures are equalized. This allows the product to fall into the chamber  205  when the upper gate valve  203  is opened and pressure will not push it back toward the vacuum marinator  10 . The upper gate valve  203  is opened and allows the product to drop through into the chamber  205 . Once enough time has elapsed for the product to drop into the chamber  205 , the upper slide gate  203  closes. At this time, the lower gate valve  204  opens and the ball valves  206 ,  212  cycle to put pressure on the chamber  205  from the pressure source  208 . This pushes the product out of the chamber  205  and through outlet piping  210  to the weigh hopper  211 . The lower slide gate  204  is then closed and the ball valves  206 ,  212  cycle to allow the chamber  205  to be connected to atmospheric pressure  207 . Once enough time has elapsed for the pressure in the chamber  205  to be relieved, the ball valves  206 ,  212  to cycle to connect the chamber  205  to the internal chamber  30  to equalize the pressures again. The weigh hopper  211  records the weight of the product coming out and repeats this cycle as often as necessary to keep up with the desired outlet rate. 
         [0040]    The present invention has been described with reference to certain preferred and alternative embodiments that are intended to be exemplary only and not limiting to the full scope of the present invention as set forth in the appended claims.