Abstract:
A contactor apparatus is adapted to expose a comminuted foodstuff such as comminuted meat to a processing fluid such as gaseous or aqueous ammonia or carbon dioxide gas. The contactor apparatus facilitates an even and consistent exposure to the processing fluid throughout the comminuted foodstuff as the foodstuff is pumped through a conduit. In order to produce this desired exposure to the processing fluid, the apparatus shapes the comminuted foodstuff into a relatively thin sheet of material flowing through a contact passage. The processing fluid is then applied to this relatively thin sheet of comminuted material from a processing fluid chamber. A fluid communication arrangement between the fluid chamber and the contact passage allows the flow of processing fluid into the contact passage and into contact with the sheet of foodstuff flowing through the contact passage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 09/579,783, filed May 26, 2000, entitled “METHOD FOR TREATiNG AMMONIATED MEATS,” now U.S. Pat. No. 6,406,728, which is a divisional application of U.S. patent application Ser. No. 09/286,699, filed Apr. 6, 1999, entitled “APPARATUS FOR TREATING AMMONIATED MEATS,” now U.S. Pat. No. 6,142,067. The entire contents of both of these patents are hereby incorporated herein by this reference. 

   TECHNICAL FIELD OF THE INVENTION 
   The invention relates to foodstuff processing and, more particularly, to an apparatus and method for exposing comminuted foodstuffs to a processing fluid such as ammonia gas or aqueous ammonia. 
   BACKGROUND OF THE INVENTION 
   Certain food processing operations require adding processing fluids to a foodstuff. U.S. Pat. No. 5,871,795, for example, discloses a method using ammonia and/or carbon dioxide to modify the pH of a meat product. The treatment disclosed in U.S. Pat. No. 5,871,795 has been shown to decrease pathogenic microbe content in meat products. U.S. Pat. No. 6,389,838 also discloses a process in which a pH modifying material such as gaseous or aqueous ammonia is applied to meat products as part of an overall process that includes freezing and physically manipulating the pH modified meat product. 
   Treatment processes that expose foodstuffs to a processing fluid may require a controlled and consistent application of the processing fluid. Depending upon the treatment process, underexposure may not provide the desired results, while overexposure to the processing fluid may produce undesirable results. In the pH adjustment processes described in U.S. Pat. Nos. 5,871,795 and 6,389,838 for example, portions of the meat product being treated may be overexposed to the pH adjusting fluid while other portions of the meat product may be exposed to very little or none of the pH adjusting fluid. The overexposed portions may absorb sufficient adjusting fluid to affect the taste of the treated product and to produce a residual pH adjusting material odor. Underexposed portions of the meat product may not exhibit the desired pathogenic microbe inhibiting effect. 
   SUMMARY OF THE INVENTION 
   A contactor or sparger apparatus according to the present invention is adapted to expose a comminuted foodstuff such as comminuted meat to a processing fluid such as gaseous or aqueous ammonia or carbon dioxide gas. The apparatus facilitates an even and consistent exposure to the processing fluid throughout the comminuted foodstuff as the foodstuff is pumped through a conduit. In order to produce this desired exposure to the processing fluid, the apparatus shapes the comminuted foodstuff into a relatively thin sheet of material flowing through a contact passage. The processing fluid is then applied to this relatively thin sheet of comminuted material from a processing fluid chamber located adjacent to the contact passage. A fluid communication arrangement between the fluid chamber and the contact passage allows the flow of processing fluid into the contact passage and into contact with the sheet of foodstuff flowing through the contact passage. 
   The contactor apparatus may use various structures to shape the comminuted foodstuff into the desired thin sheet of material. In one preferred form of the apparatus, the contact passage is defined between two substantially parallel and planar contact passage walls which force the comminuted foodstuff into a thin planar sheet of material as it flows through the contactor apparatus. In another preferred form, the contact passage is defined as an annular area between a contact passage inner wall and a contact passage outer wall. The sheet of comminuted foodstuff in this form of the invention comprises a cylindrically shaped sheet of material formed as the comminuted foodstuff flows through the annular contact passage. 
   One preferred form of the apparatus includes a contactor body having an inlet end adapted to receive comminuted foodstuff and an outlet end for passing the comminuted foodstuff on to further processing equipment after the foodstuff has been exposed to the processing fluid. The contact passage is located between the contactor body inlet end and outlet end. A portion of the contactor body inlet generally transitions down from inlet flow dimensions to the dimensions required to produce the desired thin sheet of material in the contact passage. A portion of the contactor body outlet similarly transitions back from the dimensions of the contact passage to the outlet dimensions that are not restricted by the dimensions of the desired thin sheet of material. 
   The method of the invention includes forming or producing the flowing sheet of comminuted foodstuff and then exposing the flowing sheet of material to the processing fluid in at least one of the major surfaces of the sheet. In the preferred form of the invention, the transverse dimension of the flowing sheet of material is generally equal to a dimension of the foodstuff pieces making up the comminuted foodstuff. The processing fluid may enter the sheet of material through one or both of the opposing surfaces used to form the sheet. 
   The invention is particularly suited for comminuted foodstuffs such as meat or meat products, including beef, pork, lamb, and other red meats. The comminuted foodstuff may also include or be made up of poultry or sea foods. Comminuted foodstuffs that may be treated according to the present method may also include various additives or fillers. As used in this disclosure and the following claims, a “comminuted” material comprises generally a material which has been cut into relatively smaller pieces from one or more relatively larger pieces. The meat product being treated may be originally comminuted by any suitable device such as grinder or bowl chopper, or by manual trimming or cutting. 
   These and other objects, advantages, and features of the invention will be apparent from the following description of the preferred embodiments, considered along with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a somewhat diagrammatic side view of a treatment system incorporating a contactor apparatus embodying the principles of the invention, partially broken away to show the interior of the contactor apparatus. 
       FIG. 2  is an enlarged longitudinal section view through the contactor apparatus shown in  FIG. 1 . 
       FIG. 3  is a further enlarged longitudinal section view through a portion of the contactor apparatus shown in  FIG. 1 . 
       FIG. 4  is a view in perspective of an alternate contactor apparatus embodying the principles of the invention. 
       FIG. 5  is a view in section taken along line  5 - 5  in  FIG. 4 . 
       FIG. 6  is an enlarged view in section showing a portion of the insert in  FIG. 5 . 
       FIG. 7  is a right end view of the alternate contactor apparatus shown in  FIG. 4 . 
       FIG. 8  is a view in section similar to  FIG. 5 , but showing an alternate fluid communication arrangement according to the invention. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 1 through 3  illustrate one preferred form of treatment system  10  employing a contactor or sparger apparatus  15  embodying the principles of the invention. Treatment system  10  includes an initial comminuting device  11  and a further comminuting device  12 . Also, treatment system  10  includes a metering device  14  for directing the foodstuff through contactor apparatus  15 . 
   Both of the comminuting devices  11  and  12  in this treatment system comprise grinders such as the Model No. 1109 grinder by Weiler &amp; Company, Inc. Grinder  11  receives relatively large pieces of foodstuff such as meat product  20  and produces an initial or original comminuted meat product  21 . The grinder plate associated with grinder  11  may include openings having a maximum dimension preferably between approximately two (2) inches and three-eighths (⅜) of an inch. In a more preferred form of the system, the grinder plate openings in grinder  11  have a maximum dimension of between one-half (½) of an inch to three-eighths (⅜) of an inch. The maximum dimension of the openings in the grinder plate generally determines the maximum dimension of the comminuted material exiting the grinder. 
   It will be appreciated that the original comminuted product  21  exiting grinder  11  is made up of a plurality of discrete pieces arranged together in a continuous mass. Individual pieces are represented in the drawings at reference numeral  25 . Since these individual pieces are mixed together with other discrete pieces, they are not necessarily visible individually from the collective mass of material. However, the discrete pieces  25  are shown for purposes of explaining the operation of the invention. 
   In treatment system  10 , grinder  12  receives the original comminuted meat product after the material has been exposed to a processing fluid such as gaseous or aqueous ammonia in the contactor apparatus  15 . Grinder  12  further comminutes the original comminuted material and may include a grinder plate having openings smaller than the openings in the grinder plate associated with grinder  11 . For example, grinder  12  may include a grinder plate having openings with a maximum dimension of no greater than three-sixteenths ( 3/16) of an inch and preferably about one-eighth (⅛) of an inch. Alternatively, the grinder plate associated with grinder  12  may have the same size openings as grinder  11  and still perform some comminuting. In any event, the further comminuted material  22  exits grinder  12  and is collected for packaging or for transport to further processing equipment.  FIG. 1  shows the further comminuted material  22  being collected in a receiving tub  23 . 
   In the treatment system  10  shown in  FIG. 1 , metering device  14  comprises a suitable positive displacement metering device. Metering device  14  receives the comminuted foodstuff  21  in collection chute  27  and then meters the comminuted foodstuff through processing fluid contactor  15  as indicated by the flow direction shown at arrow F. Other forms of the treatment system may use other means for forcing the comminuted foodstuff into and through contactor  15 . The particular metering or pumping device will include a motor for driving the device with sufficient power to force the comminuted foodstuff through contactor  15  and the conduits leading to and from the contactor. 
     FIGS. 2 and 3  show further details of contactor apparatus  15  shown in  FIG. 1 . Contactor  15  includes a contactor conduit or body  30  having a processing fluid chamber  31  positioned therein. The illustrated form of the invention shows chamber  31  positioned coaxially within contactor conduit  30 , although the chamber may be mounted eccentrically in the contactor conduit within the scope of the invention. As shown best in  FIG. 3 , the coaxial arrangement leaves a uniform annular contact passage  32  defined between the inner wall  34  of contactor conduit  30  and the outer surface  35  of chamber  31 . Contact passage  32  forms a portion of a flow passage for the comminuted foodstuff through contactor  15 . Chamber  31  also includes an interior area  36  and a communication arrangement comprising a plurality of openings  38  which extend from the chamber interior area to the annular contact passage  32 . For processing comminuted meat products, the openings may be one thousandth of an inch in diameter or greater, and preferably no larger than about six thousandths of an inch in diameter. Finally, contactor  15  includes a supply tube  39  which is connected to feed a processing fluid from a supply (not shown) to the chamber interior area  36 . Thus, supply tube  39  provides a fluid path from a point outside contactor conduit  30  to the interior area  36  of chamber  31 . 
   The form of the chamber  31  illustrated in the figures includes openings  38  which have been drilled or otherwise formed through the chamber wall. Other forms of the invention may include a chamber having walls made of a sintered material or other material that is permeable to the processing fluid. In still other forms of the invention, the contactor conduit wall may include machined openings or sections of permeable material. An annular supply chamber may be located around the contactor conduit for containing a processing fluid. This additional fluid communication arrangement may be used instead of, or in addition to, the inner chamber form of the invention which uses chamber  31  shown in  FIGS. 1 through 3 . 
   In the form of contactor shown in  FIG. 1 through 3 , the distance between contactor conduit inner wall  34  and the chamber outer surface  35 , that is, the minimum dimension of the contact passage  32 , may be any distance that will allow the original comminuted foodstuff  21  to be metered through the contact passage without substantially damaging the foodstuff. For example, the width of the annulus (between wall  34  and surface  35 ) may be around two inches. A preferred width of the annulus is between one-half (½) to one-eighth (⅛) of an inch, or no greater than the approximate maximum dimension of the pieces of material making up the comminuted foodstuff being treated in the contactor. 
   The treatment process performed by system  10  and the operation of contactor  15  may now be described with reference to  FIGS. 1 through 3 . Referring to  FIG. 1 , meat  20  is ground or otherwise comminuted to form the original comminuted meat product  21 . This comminuted meat product is collected in metering device chute  27  and forced by metering device  14  through processing fluid contactor  15 . In processing fluid contactor  15 , at least a portion of the comminuted meat product  21  is exposed to the processing fluid such as aqueous or gaseous ammonia. The meat product passes from contactor  15  to grinder  12  where the material is preferably further comminuted. The further comminuted meat product  22  is expelled from device  12  and collected for packaging or for further processing. 
   In contactor  15 , a thin layer of comminuted meat pieces  25  passes through contact passage  32 . Preferably the thin layer comprises a single layer of individual comminuted meat pieces  25 . The pieces  25  are exposed to the processing fluid on at least one surface as that surface passes over an opening  38  in chamber  31 . Also, some processing fluid may flow from chamber  31  into the comminuted material mass as the material passes openings  38 . For gaseous or aqueous ammonia exposure, the pressure in chamber  31  is controlled so that the pH of the further comminuted meat product  22  is at least about 6.0, or in the range from 6.0 to 11.0. 
   The foodstuffs may be processed according to the invention in a wide temperature range. For example, meat may be maintained at a temperature above 32° F. for both the process fluid contacting step and the further comminuting step. In any event, the meat product temperature should be high enough that some liquid component remains in the meat product during the further comminuting step. 
     FIGS. 4  though  8  show alternate contactor or sparger devices embodying the principles of the present invention. The perspective view of  FIG. 4  shows the general structure of an alternate contactor device  40 , while  FIGS. 5 and 8  show two fluid communication variations within this general structure. The end view shown in  FIG. 7  is substantially identical in both alternate forms of invention shown in  FIGS. 5 and 8 . 
   Contactor  40  includes generally a contactor body formed by two components  41  and  42  and includes a foodstuff flow passage from a first end of the contactor body to a second end. The foodstuff flow passage in this form of the invention includes a first end or inlet end portion shown generally at reference numeral  44  and a second end or outlet end portion shown generally at reference numeral  45 . These end portions  44  and  45  of the foodstuff flow passage are separated by a contact passage shown generally at reference numeral  46 . As shown best in  FIGS. 5 and 8 , contact passage  46  is actually formed through a separate insert mounted within the contactor body. This insert is shown at reference numeral  48  in  FIG. 5 , and  48 ′ in  FIG. 8 . The fluid communication arrangement in this form of the invention is associated with this insert as will be described further below. In both alternatives of the invention shown in  FIGS. 5 and 8 , a processing fluid chamber  49  is included in the contactor body. Processing fluid chamber  49  comprises an annular area encompassing the respective insert  48  or  48 ′, and the insert separates fluid chamber  49  from contact passage  46 . 
   The two end components  41  and  42  are flanged together with a flange connection shown generally at reference numeral  51 . The illustrated form of contactor  40  also includes a flange  52  at one end for connecting the device to a suitable conduit, and a threaded connector  53  at the opposite end for connecting the opposite end to a suitable conduit. Although flange and threaded connectors are shown in the illustrated embodiment, it will be appreciated that the invention is by no means limited to these types of connectors. Also, although the two-piece arrangement (components  41  and  42 ) shown in the figures is preferred for its durability, ease of construction, and ease of assembly and disassembly, the invention is not limited to this two-piece contactor body. 
   It will be noted particularly from the section views of  FIGS. 5 and 8  that the first and second end portions,  44  and  45  respectively, of the foodstuff flow passage generally define flow areas. The minimum transverse dimension of each end portion flow area reduces down from a relatively large transverse dimension at the outer ends of the flow passage to a relatively smaller minimum transverse dimension in a flow area defined by contact passage  46 . As shown best in the end view of  FIG. 6 , the preferred contact passage  46  forms an elongated oval in transverse cross section. Contact passage  46  is thus defined between two narrowly spaced opposing surfaces or contact passage walls indicated by reference numerals  56  and  57 . These two surfaces  56  and  57  are both generally planar and extend parallel to each other. When a comminuted foodstuff is forced to flow through the contactor  40 , the foodstuff is forced into contact passage  46  where it forms a thin planar sheet of material. This relatively narrow sheet of the foodstuff is similar to the annular or cylindrical sheet of foodstuff described above in connection with the embodiment of the invention shown in  FIGS. 1 through 3 . Both sheets of material have a relatively small minimum transverse dimension, preferably on the order of a dimension of the pieces of material making up the comminuted foodstuff being treated. 
   Process fluid chamber  49  in the forms of the invention shown in  FIGS. 4 through 8  comprises an annular area machined or otherwise formed in components  41  and  42  around the area that receives insert  48  or  48 ′. This annular area is shown divided by ribs  60  into separate longitudinally spaced apart chambers  61  in communication with each other through rib openings  62 . Ribs  60  help support the respective insert  48  or  48 ′ in the desired position. Processing fluid may enter chamber  61  though a processing fluid passage  64  formed in contactor body end component  41 . Processing fluid passage  64  may also be associated with a suitable connection  65  for connecting to a processing fluid supply conduit (not shown) for supplying processing fluid to contactor  40 . 
   The fluid communication arrangement in the form of the invention shown in  FIG. 6  includes a number of the small openings  67  drilled or otherwise formed through the material of insert  48  separating contact passage  46  and processing fluid chamber  49 . These openings  67  preferably have a small transverse dimension no greater than about 0.10 inches for processing comminuted meats, and are illustrated in the enlarged section view of  FIG. 6 . Although openings  67  may be any size that allows the desired processing fluid contact with the foodstuff, the small openings are preferred because they allow processing fluid to flow from processing fluid chamber  49  into contact passage  46  to effect the desired contact with the foodstuff, but help prevent the foodstuff from flowing from the contact passage into the processing fluid chamber. It will also be appreciated that the processing fluid pressure maintained in chamber  49  also prevents foodstuffs from inadvertently flowing through openings  67  from contact passage  46  into processing fluid chamber  49 . In the preferred form of the invention, a large number of the openings  67  are spaced apart across the entire width of each contact passage wall  56  and  57  in each chamber  61 . Openings  67  are also preferably included in both lateral ends of contact passage  46 . 
   An alternate form of the invention, shown in  FIG. 8  employs a porous and permeable material for the insert  48 ′ in place of the solid and machined insert  48  shown in  FIGS. 5 and 6 . This material is permeable to the processing fluid and thus allows the processing fluid to flow from processing fluid chamber  49  into contact passage  46  under a suitable driving pressure differential between the processing fluid chamber and contact passage. However, the openings that produce the desired permeability are preferably small enough to inhibit foodstuff from flowing from contact passage  46  into processing fluid chamber  49 . Ceramics and sintered materials or any other suitable material having the desired permeability to the processing fluid may be used to form insert  48 ′. Composite inserts made up of solid material and permeable material sections may also be employed within the scope of the invention. 
   In both the discrete opening form of the fluid communication arrangement shown in  FIGS. 5 and 6 , and the permeable material fluid communication arrangement shown in  FIG. 8 , the openings provide fluid communication from chamber  49  to contact passage  46 . That is, the openings at least allow processing fluid to pass from chamber  49  to contact passage  46  given the appropriate pressure in chamber  49 . The openings that provide the fluid communication may be sized and shaped to inhibit flow of foodstuff from contact passage  46  to chamber  49 , but it is not required. Rather, the pressure in chamber  49  may be controlled to prevent foodstuff from flowing into the openings making up the fluid communication arrangement. 
   Whether the sheet of material is planar as in contactor  40  or annular/cylindrical as in contactor  15 , or some other shape, the thin sheet of foodstuff may be exposed to the processing fluid in an even and consistent manner. That is, the relatively thin sheet of foodstuff material may be exposed on both sides or major surfaces to the processing fluid. Where the spacing between the opposing surfaces of the contact passage is approximately equal to a dimension of foodstuff pieces making up the comminuted foodstuff, applying the processing fluid to the thin sheet generally ensures that each piece of the foodstuff if directly exposed to the processing fluid. This is to be contrasted with the situation in which a processing fluid is simply injected into a foodstuff flowing through a large conduit. In that case the processing fluid is inherently applied unevenly with some pieces directly exposed and other pieces exposed only indirectly. 
   The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit the scope of the invention. Various other embodiments and modifications to these preferred embodiments may be made by those skilled in the art without departing from the scope of the following claims. For example, the invention is not limited by specific materials for the various contactor components. Generally, the contactor body components may be formed from stainless steel, however, any material suitable for food handling may be used provided the material has suitable strength and other material characteristics. Porous and permeable material used in the fluid communication arrangement may comprise any suitable material. Also, the invention is not limited to a contact passage minimum transverse dimension equal to a dimension of the foodstuff pieces being treated. A single layer or line of foodstuff pieces passing through the contact passage is preferred for the reasons described above, but is not required.