Abstract:
Apparatus and methods for pasteurizing food product are provided. The apparatus includes a cabinet enclosing the food product as it is transported from upstream to downstream through a series of processing zones including a pre-condensing zone, a pre-heating zone, a pasteurizing zone, a post-heating zone, and a post-condensing zone. In use, the food product is conveyed through the series of processing zones, which together function to efficiently and effectively heat and apply pasteurizing steam to the surfaces of the product to kill bacteria, while at the same time managing migration of steam from the pasteurizing zone and preventing steam from migrating out of the cabinet into the surrounding area.

Description:
BACKGROUND 
     The present application is directed to improved apparatus and methods for controlling contamination of food products in a food processing environment. The apparatus and methods described herein maintain food quality and reduce the risk to the public from food-borne pathogens. 
     Although generally preventable, food-borne illness remains a serious problem in the United States. Contaminated food has been estimated to cause 76 million illnesses in the United States each year, including 325,000 cases resulting in hospitalization. The Council for Agricultural Science and Technology has estimated that food-borne diseases caused by the most common bacterial pathogens found in ready-to-eat (RTE) foods— Listeria monocytogens, Campylobacter jejuni, Escherichia coli, Salmonella  and  Staphylococcus aureus —may cause as many as 9,000 deaths each year. The present application discloses methods and systems that will benefit public health by eliminating or reducing food-borne pathogens from RTE foods. 
     Researchers and processors have been working for years on developing and implementing post-cook (post-process) lethality treatments for at-risk RTE meats. The industry has options for both pre- and post-packaging lethal treatments, including steam, hot water, radiant heat, and high-pressure processing. Application of steam surface pasteurization allows post-process lethality treatments to be achieved at a production line speed that is comparable to that of commercial packaging for RTE foods. 
     There is a continuing need for more efficient, more effective, and simplified methods and systems for treating the surface of a food product to kill and/or significantly reduce the growth of food-borne pathogens. 
     SUMMARY 
     The present application describes apparatus and methods for pasteurizing food product and for providing more efficient, effective, and simplified means for treating the surface of the food product to kill and/or significantly reduce the growth of food-borne pathogens. In the illustrated embodiment, a cabinet encloses the food product as it is transported on a conveyor from upstream to downstream through a series of processing zones. The processing zones include a pre-condensing zone for condensing steam from air surrounding the food product, a pre-heating zone evaporating excess water from surfaces of the product and potentially superheating steam surrounding the food product, a pasteurizing zone applying pasteurizing steam to the surfaces of the product, a post-heating zone evaporating excess water from the surfaces of product and potentially superheating steam surrounding the food product, and a post-condensing zone condensing steam from air surrounding the food product. In use, the food product is conveyed through the series of processing zones, which together function to efficiently and effectively pasteurize the surfaces of the product to kill bacteria, while at the same time manage migration of steam from the cabinet into the surrounding area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The best mode of practicing the invention is described hereinbelow with reference to the following drawing figures. 
         FIG. 1  is a sectional elevation view of apparatus for pasteurizing food product. 
         FIG. 2  is a view of Section  2 - 2  taken in  FIG. 1 . 
         FIG. 3  is a view of Section  3 - 3  taken in  FIG. 1 . 
         FIG. 4  is a view of Section  4 - 4  taken in  FIG. 1 . 
         FIG. 5  is a view of Section  5 - 5  taken in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a side elevation view showing a cabinet  10  that includes a tunnel  12  for passage of food products such as pre-cooked, unwrapped bologna, meat, hams, an/or other whole muscle products. An endless conveyor  14  transports the food product through the tunnel  12  from upstream  16  to downstream  18 . The cabinet  10  includes a series of processing zones  20 - 28  for treating surfaces of the food product and, more specifically, killing and/or significantly reducing growth of food-borne pathogens, and for controlling migration of steam from the cabinet  10 . The processing zones  20 - 28  include a pre-condensing zone  20 , a pre-heating zone  22 , a pasteurizing zone  24 , a post-heating zone  26  and a post-condensing zone  28 . The tunnel  12  extends through each of the zones  20 - 28  and forms a pathway for the food product to travel through the zones  20 - 28  in series. Each zone  20 - 28  is separated from adjacent zones by a baffle  30   a - 30   f , which preferably consists of a silicone drape having a plurality of vertical slits  32  which define respective door flaps  33 . The conveyor  14  carries the food product from upstream  16  to downstream  18  and through each zone  20 - 28 . As it travels from one zone to the next, the food product passes through a respective silicone baffle  30   a - 30   f . Specifically, the door flaps  33  of each baffle  30   a - 30   f  separate to allow passage of the food product. Advantageously, the baffles  30   a - 30   f  physically separate the zones  20 - 28  and allow for separate temperature control for each zone  20 - 28 . However, even though the baffles  30   a - 30   f  provide the noted separation, a certain amount of air and steam passes through the baffles  30   a - 30   f  and travels amongst the respective zones  20 - 28 . The unique combination of processing structures detailed herein below provides an efficient and effective means for pasteurizing the food product while controlling migration of steam and preventing infiltration of steam to the areas surrounding the pasteurization cabinet  10 . 
       FIGS. 1 and 2  show structures of the pre-condensing zone  20 . Food product enters the pre-condensing zone  20  at the load end  34  of the cabinet  10  via baffle  30   a . Water condensing nozzles  36  receive a supply of water and distribute supplies of atomizing mist  38  into the pre-condensing zone  20  to facilitate condensation of any steam that migrates into the pre-condensing zone  20  from the adjacent, subsequent pre-heating zone  22 . A set of baffles  46  advantageously block the supply of mist  38  from contacting the food product as it travels through the zone  20  on conveyor  14 . As shown, the baffles  46  extend perpendicular to the conveyor  14  and preferably extend upwardly past the lower end of the nozzles  36 . Advantageously, the orientation of the nozzles  36  and baffles  46  cause steam to draw away from the tunnel  12  and the food product on the conveyor  14 , as shown by arrows  48 . The steam is condensed into the lower portion  40  of the pre-condensing zone  20  and drains under removable wall  43  and migrates via gravity down to cabinet drain  44 . The pre-condensing zone  20  thus advantageously condenses any migrant steam from the subsequent processing zones and prevents such steam from exiting the cabinet  10  via the baffle  30   a  and entering the surrounding area. The unique combination also advantageously eliminates the need for a dedicated drying fan at the upstream loading end of the cabinet  10 . 
       FIGS. 1 and 3  show structures of the pre-heating zone  22 . The food product enters the pre-heating zone  22  by traveling along the conveyor  14  and passing through internal baffle  30   b . The pre-heating zone  22  is equipped to heat the product a sufficient amount to remove moisture from the surfaces of the food product, to sufficiently thaw the outer layer of the food product (if the product is provided initially in a frozen state), and to kill some amount of bacterial present on the surfaces of the food product. In the preferred embodiment, electrical heating elements  50  provide a heat source for controlling the temperature of the pre-heating zone  22  to a predetermined condition set point. In a further preferred arrangement, the electrical heating elements  50  are designed to superheat the heating zone  22  to a temperature that is greater than 212° Fahrenheit. The superheated zone  22  provides a desired kill rate of bacteria on the surfaces of the food product and, when combined with the subsequent pasteurization step described below, the superheated zone is useful to heat the surfaces of the product and allow thus maximum pasteurization using the application of steam. 
     Another beneficial effect of the pre-heating process and preferably the super-heating process is that any steam that migrates into the pre-heating zone  22  from the subsequent pasteurizing zone  24  is superheated. The superheating of steam in the pre-heating zone  22  advantageously limits the migration of steam out of the cabinet  10  and into the surrounding control room. That is, heating the air in the pre-heating zone  22  dries the air and thus allows the air to hold an increased amount of moisture relative to the adjacent zones  20 ,  26 , thus discouraging migration of moisture out of the pre-heating zone  22 . 
     The superheated steam in the pre-heating zone  22  is advantageously evacuated via a false roof  52  in the tunnel  12 . Specifically, an exhaust fan  54  draws the superheated steam out of the pre-heating zone  22  via the false roof  52  in the tunnel  12 . As shown in  FIGS. 1 and 4 , the exhaust fan  54  draws the steam from the tunnel  12  and discharges it to a condenser  56 . Condenser  56  includes a spray nozzle  58  for spraying an atomizing mist into tee  60 . The atomizing mist facilitates condensation of the exhausted steam into condenser section  62 . The condenser pipe is subsequently reduced in reducer  64  and further discharged to cabinet drain  44  via piping  66 . 
       FIGS. 1 and 4  show structures of the pasteurizing zone  24 . The food product exits the pre-heating zone  22  and enters the pasteurizing zone  24  by passing through internal baffle  30   c . The pasteurizing zone  24  includes a plurality of steam nozzles  68  arranged to spray pasteurizing steam, preferably at a low pressure and high velocity, directly onto the surfaces of the food product as it travels along the conveyor  14 . As described above, the surfaces of the food product have previously been heated in the pre-heating zone  22 . Application of the pasteurizing steam therefore further raises the temperature of the surfaces of the food product to obtain maximum desired log kill of bacteria remaining on the food product. Steam nozzles  68  receive the pasteurizing steam from an external source via a steam supply piping assembly  70 . 
     Advantageously, the pasteurizing zone  24  is equipped to cover the entire surface area of the food product with pasteurizing steam. As shown in  FIGS. 1 and 5 , conveyor  14  includes a downward loop  72  that defines a gap  74  in the conveyor. Gap  74  facilitates application of pasteurizing steam to the lower surfaces of the food product. Downward loop  72  is rotatably supported by adjacent conveyor sprockets  76   a  and  76   b  and a third, lower conveyor sprocket  77  that is preferably positioned between the conveyor sprockets  76   a  and  76   b.    
     Preferably, the pasteurizing zone  24  does not include a vent for evacuating pasteurizing steam; and thus the pasteurizing steam is encouraged to stay in the pasteurizing zone  24  and contact all surfaces of the food product. However, during operation, some of the pasteurizing steam tends to migrate from the pasteurizing zone via the internal baffles  30   c  and  30   d . Steam that passes through internal baffles  30   c  and  30   d  is either exhausted through the false roofs  52  present in the pre-heating zones  22 ,  26  by the exhaust fan  54 . Also, steam that migrates out of the pre- and post-heating zones  22 ,  26  and into the pre- and post-condensing zones  20 ,  28  is condensed and drained to the common cabinet drain. Thus the combination of the pre- and post-heating zones and the pre- and post-condensing zones  20 ,  28  advantageously prevents migration of steam into the surrounding environment. 
       FIG. 1  shows the structure of post-heating zone  26 , which is substantially a mirror image of the pre-heating zone  22 . Reference is therefore also made to  FIG. 3  for discussion and exemplification purposes. The food product exits the pasteurizing zone  24  and enters the post-heating zone  26  by passing through internal baffle  30   d . Once inside the post-heating zone  26 , heating elements that mirror the heating elements  50  heat the food product to remove any condensate on the surfaces thereof. Similar to the pre-heating zone  22 , the post-heating zone  26  is equipped to heat the product a sufficient amount to remove moisture from the surfaces of the food product and further kill at least some amount of bacteria present on the surfaces of the food product. In the preferred embodiment, electrical heating elements (e.g.  50  shown in pre-heating zone  22 ) provide a heat source for the post-heating zone  26 . In a preferred arrangement, the heating elements are designed to superheat the post-heating zone  26  to a temperature that is greater than 212° Fahrenheit. The superheated post-heating zone  26  provides desired maximization of kill rate of bacteria on the surfaces of the food product and limits migration of steam into the adjacent post-condensing zone  28 . 
     As in the pre-heating zone  22 , one possible effect of the superheating process in the post-heating zone  26  is that steam that migrates into the post-heating zone  26  from the pasteurizing zone  24  is superheated. Such superheated steam is advantageously evacuated from the post-heating zone  26  via a false roof  52  in the tunnel  12 . Exhaust fan  54  draws the superheated steam out of the post-heating zone  26  via the false roof  52  in the tunnel  12 . As shown in  FIGS. 1 and 4  and discussed above, the exhaust fan  54  draws the steam from the tunnel  12  and discharges it to a condenser  56 . 
       FIG. 1  shows the structure of the post-condensing zone  28 , which is substantially a mirror image of the pre-condensing zone  20 . Food product exits the post-heating zone  26  and enters the post-condensing zone  28  by passing through internal baffle  30   e . Similar to the pre-condensing zone  20 , the post-condensing zone  28  has water condensing nozzles  36  that receive a supply of water and distribute supplies of atomizing mist into the post-condensing zone  28  to facilitate condensation of any steam that migrates into the post-condensing zone  28  from the adjacent post-heating zone  26 . A set of baffles similar to baffles  46  in the pre-condensing zone  20  block the supply of mist and prevent the supply of mist from contacting the food product as it travels through the zone  28  on conveyor  14 . The baffles extend perpendicular to the conveyor  14  and preferably extend upwardly past the lower end of the nozzles. Advantageously, the orientation of the nozzles and baffles cause steam to draw away from the tunnel  12  and the food product on the conveyor  14  (as for example shown by arrows  48  in  FIG. 2 ). The steam is condensed into the lower portion of the post-condensing zone  28  and drains via gravity down to cabinet drain  44 . 
     The food product exits the post-condensing zone  28  by passing through a final baffle  30   f  and travels further on conveyor  14  for additional processing and/or packaging. 
     The operation of the conveyor and/or processing zones  20 - 28  is preferably controlled by a controller (not shown). In the preferred embodiment the controller comprises a computer processor that communicates with a plurality of sensors provided in the system. The sensors can include movement sensors, temperature sensors, humidity sensors, or any other type of sensor that facilitates efficient monitoring and control of the pasteurization process. The controller and sensors thus provide independent control of the temperature and processes in each respective zone  20 - 28 . Also, the conveyor and respective zones can operate continuously or intermittently to promote efficiency. For example, in the preferred embodiment, at least one photo-eye sensor is positioned outside the pre-condensing zone  20  and senses and informs the controller of the existence of a food product on the conveyor. The controller can then provide operation of specific processes in the zones dependent upon the existence of food product on the conveyor. For example, the controller can turn the supply to nozzles  36  on and off depending upon whether food product is on the conveyor and thus decreasing waste and increasing efficiency of operation. That is, the controller can turn the supply of steam to the pasteurizing zone on and off depending upon the existence of food product on the conveyor. The controller can also or alternatively turn the heating elements in a heating zone on or off depending upon whether the temperature in the respective zone is below or above a predetermined set point. 
     It should be understood that the drawings and specification are to be considered an exemplification of the principles of the invention, which is more particularly defined in the appended claims. The term pasteurization is used herein in accordance with its normal dictionary definition, including partial sterilization of a substance at a temperature and for a period of exposure that destroys objectionable organisms without major chemical alteration of the substance, and including destruction of pathogenic and/or spoilage organisms for extending shelf life. The pasteurizing medium is preferably steam, or alternatively hot air or superheated steam, though other types of pasteurizing media may be used.