Patent Document

TECHNICAL FIELD OF THE INVENTION 
     This invention relates to foodstuff processing. More particularly, the invention relates to an apparatus and method producing a desired, target pH in a foodstuff. 
     BACKGROUND OF THE INVENTION 
     Foodstuff processing systems may utilize a pH modification step as part of an overall process. The pH modification may entail adding a pH modifying material to a foodstuff and then mixing the foodstuff and pH modifying material to produce a pH-modified foodstuff. U.S. Pat. No. 5,871,795, for example, discloses an apparatus and method for adding ammonia to a foodstuff to increase in the pH of the foodstuff. It is also possible to modify the pH of a foodstuff by adding a pH reducing material to the foodstuff. Carbon dioxide may serve as a pH reducing material for certain foodstuffs. 
     U.S. patent application Ser. No. 09/286,699 entitled “APPARATUS FOR TREATING AMMONIATED MEATS,” now U.S. Pat. No. 6,142,067, shows an apparatus and method for treating ammoniated meats, that is, meats which have been exposed to ammonia. The apparatus disclosed in this patent includes an ammonia contactor and a mixing arrangement. Ammonia is added to an initial foodstuff in the contactor and then distributed throughout the foodstuff in the mixing arrangement. This combination of ammonia contactor and mixing arrangement produces a foodstuff having a generally uniform increased pH throughout the material. 
     The foodstuff pH modification shown in U.S. patent application Ser. No. 09/286,699 must be carefully controlled to produce the desired result. Over modifying the pH in the foodstuff may affect the taste or other qualities of the foodstuff. On the other hand, insufficient pH change in the foodstuff may diminish the effectiveness of the overall foodstuff processing system. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an apparatus and method for modifying the pH of a foodstuff. More particularly, it is an object of the invention to provide a pH modifying method which facilitates improved pH control. Another object of the invention is to provide a pH modifying apparatus with improved pH control capability. 
     The method according to the invention includes providing a first foodstuff at a first pH and a second foodstuff at a second pH. The first pH and second pH are both related to a third or target pH for the foodstuff. More particularly, the first pH is either higher or lower than the target pH while the second pH bears the opposite relation to the target pH. For example, where the first pH is higher than the target pH, the second pH is lower than the target pH. Alternatively, where the first pH is lower than the target pH, the second pH is higher than the target pH. The method includes combining the first foodstuff with the second foodstuff in a proportion to produce a combined or third foodstuff at the target pH. 
     The proportion at which the first foodstuff and second foodstuff is combined is determined by the values of the first pH and second pH. The first and second pH are sensed or otherwise determined, preferably on a continuous basis, and then these pH values are used to determine the proportion at which the first foodstuff and second foodstuff are combined and mixed. For example, the first foodstuff may comprise the foodstuff to which a pH modifying material such as ammonia has been added. The pH modification can be loosely controlled to produce an over modification in the first foodstuff and then the second foodstuff may be combined with the first foodstuff according to the invention to produce a combined foodstuff having the target pH. 
     The method according to the invention may be performed in a continuous or batch process. In continuous processes, the invention is particularly advantageous because it facilitates improved control over the pH modification, and a means for moderating an over modified pH without interrupting the continuous process. The present method of modifying pH is helpful in a batch process in that it allows a component in a mixed foodstuff to be used to produce a more desirable pH in the mixed foodstuff. 
     An apparatus according to the invention includes an initial foodstuff supply arrangement and a pH modifying arrangement. The initial foodstuff supply arrangement provides an initial foodstuff to the pH modifying arrangement. A pH modifying material is then added to the initial foodstuff in the pH modifying arrangement, and the foodstuff is mixed to produce a uniform, pH-modified foodstuff. This pH-modified foodstuff may comprise the first foodstuff described above and set out in the following claims. 
     The apparatus according to the invention also includes a second foodstuff supply arrangement and a combining arrangement. The second foodstuff supply arrangement provides the second foodstuff, which may, for example, comprise a foodstuff in which the pH has not been modified by the addition of a pH modifying material. In any case, the combining arrangement combines the pH-modified foodstuff with the second foodstuff in the proportion required to produce the third foodstuff having the target pH. This combined foodstuff is preferably mixed together thoroughly with a suitable mixing device to ensure a uniform pH throughout the material. 
     The pH of the pH-modified foodstuff may be sensed or otherwise determined downstream from the pH modifying arrangement and the sensed pH may be used to control a flow rate of one or both the first and second foodstuff into the combining arrangement. Also, the sensed pH may be used to control the addition of pH modifying material in the pH modifying arrangement. 
     The apparatus and method according to the invention provide an important control function for continuous processes which utilize a pH modifying step. Although it may be difficult or undesirable to precisely control the pH modification by addition of a pH modifying material, the invention compensates by allowing precise control over the proportion at which the two foodstuff streams are combined. Furthermore, the apparatus and method according to the invention may provide benefits in the way the target pH is obtained. In particular, a pH modifying step in a foodstuff processing system may be more effective by first over modifying the pH of a foodstuff and then bringing the pH back to a target pH level. Also, the invention allows an untreated foodstuff to obtain the benefit of a pH modification without having to add pH modifying material directly to the foodstuff. 
     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 diagrammatic representation of an apparatus embodying the principles of the invention for providing pH modification in a foodstuff. 
     FIG. 2 is a flow chart showing the process steps according to the invention for controlling pH modification in a foodstuff. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a pH modifying apparatus  10  embodying the principles of the invention includes an initial foodstuff supply  11  which feeds an initial foodstuff to two separate streams, labeled A and B in the figure. One stream of foodstuff, stream A, is processed through a pH modifying arrangement  12  and then the two streams A and B are combined in combining arrangement  14  to produce a third stream C in FIG.  2 . The preferred form of the invention includes a pH sensing arrangement  15  for sensing the pH of the pH-modified foodstuff. This sensed pH is then used in determining the proportion at which the two streams A and B are mixed in combining arrangement  14  to produce the desired pH in the third stream C. 
     Stream A is carried in a first conduit  18  having an inlet connected to initial foodstuff supply  11  and an outlet connected to combining arrangement  14 . Stream B is carried in a second conduit  19  having an inlet end connected to the initial foodstuff supply  11  and an outlet also connected to combining arrangement  14 . A first pump  20  is connected in first conduit  18  for forcing material through the first conduit, while a second pump  21  is connected in second conduit  19  for forcing material through the second conduit. As will be described further below, these first and second pumps  20  and  21  are preferably variable rate pumps and may comprise auger-type pumps, piston-type pumps, or any other pumping device suitable for the particular foodstuff being processed. It will be appreciated that each pump  20  and  21  is driven with a suitable motor with controls for controlling the pumping speed. These motors and controls are within the knowledge of those skilled in the art and are omitted from the figures so as not to obscure the invention in unnecessary detail. Other details, such as the specific materials from which conduits  18  and  19  and other components of the system are formed, are likewise omitted from this disclosure since the materials may be any materials suitable for use in handling the desired foodstuffs. 
     Although any pH modifying arrangement may be used for the arrangement  12 , the preferred arrangement comprises the arrangement shown in U.S. patent application Ser. No. 09/286,699, now U.S. Pat. No. 6,142,067. The entire disclosure of this document is incorporated herein by this reference. As shown in FIG. 1 of the present disclosure, pH modifying arrangement  12  includes a contactor  24  and a mixing device  25 . Contactor  24  includes a supply  26  of pH modifying material. The pH modifying material may be any material suitable for use in the particular foodstuff being processed. For example, ammonia gas or aqueous solution of ammonia comprises a suitable pH increasing material for meats and other foodstuffs. Carbon dioxide provides a suitable pH reducing material. Regardless of the type of pH modifying material or the manner in which it is added to the foodstuff, mixing device  25  functions to distribute the material throughout the foodstuff to produce a generally uniform pH throughout the foodstuff. Mixing device  25  preferably comprises a grinder as set out in application Ser. No. 09/286,699, but may comprise any suitable mixing device. 
     The pH of the pH modified foodstuff exiting mixer  25  is sensed at sensing arrangement  15 . In the preferred form of the invention, sensing arrangement  15  includes a continuous sensing device for providing a continuous pH reading for the pH modified foodstuff exiting mixer  25 . The sensing device may sense material in situ within first conduit  18  or may sense only one or more small portions of the entire stream of material within the conduit. Alternatively to the preferred continuous sensing device, the sensing arrangement  15  may include an arrangement for taking discrete samples for manual testing. This manual sensing arrangement is within the scope of the following claims. 
     Referring still to FIG. 1, combining arrangement  14  includes a first inlet  31  connected to the outlet end of first conduit  18 , and a second inlet  32  connected to the outlet end of second conduit  19 . Combining arrangement  14  also includes a single outlet  33  connected to an outlet conduit  34 . Some preferred embodiments of the invention may also include flow control or flow metering devices included in combining arrangement  14  for use in controlling the proportion at which the two foodstuff streams A and B are combined. This control may be in addition to, or an alternative to, any flow rate control provided through pumps  20  and  21  as discussed below. 
     Located downstream of combining arrangement  14 , the illustrated form of the invention includes a mixer  36  for thoroughly mixing the combined stream of material exiting the combining arrangement. Since the combined stream C includes material from both streams A and B, the material must be mixed in order to provide the desired uniform pH throughout the material. Mixer  36  may comprise any suitable foodstuff mixing device. For communicated meats, poultry, and seafood, for example, mixer  36  may comprise a grinder, blender, or bowl chopper. Regardless of the type of mixing device used for mixer  36 , an outlet pH sensing arrangement  37  may be operatively connected in the outlet conduit  34  for measuring the pH of the combined stream C. 
     According to the invention, the pH sensed at sensing arrangement  15  may be used in controlling the overall pH modification within apparatus  10 . In the preferred form of the invention, pH modifying arrangement  12  modifies the pH of the foodstuff in stream A over a desired modification amount. This overly modified pH may be brought back to a desired level in the combined stream C by adding under or non-pH modified foodstuff from stream B in the appropriate proportion defined by the respective pH of the two streams. Since the initial foodstuff in stream B may be an untreated foodstuff with a generally known pH, while the pH after the pH modifying arrangement  12  may be varied, pH sensed at arrangement  15  comprises a variable which may be used through suitable control devices to control the proportion at which the two streams A and B are combined to produce the combined stream C at the desired pH. 
     The proportions at which the two streams of foodstuff A and B are combined may be controlled by controlling the flow rate of the two streams. FIG. 1 shows that the relative flow rates may be controlled by providing a control signal through line  40  to first pump  20 . The control signal may originate from a controller  39  associated with pH sensing arrangement  15 . FIG. 1 also shows a control line  41  extending from pH sensing arrangement  15  back to second pump  21 . Either pump individually, or both pumps together may be controlled to control the proportion at which foodstuff streams A and B are combined in combining arrangement  14 . Also, a third control line  42  may provide a control signal to contactor  24 , or the supply  26  of pH modifying material associated with the contactor. This third control signal may be used along with other inputs to control the pressure of pH modifying material applied in contactor  24 , or to control a metering of pH modifying material into the contactor. 
     The method of the invention and operation of apparatus  10  shown in FIG. 1 may be described with reference to FIG.  1  and the flow chart shown in FIG.  2 . The method includes providing a first foodstuff such as stream A, and providing a second foodstuff such as stream B. The method also includes combining the two foodstuffs in a proportion to produce a third foodstuff at a desired pH, stream C. 
     Providing the stream of first foodstuff is shown generally at  50  in FIG.  2  and includes a pumping step  51  and pH modifying step  52 . Pumping step  51  comprises pumping the initial foodstuff from supply  11  in FIG. 1 to pH modifying arrangement  12  using first pump  20 . pH modifying step  52  comprises contacting the initial foodstuff with pH modifying material as shown at step  53 , and then mixing the initial foodstuff and pH modifying material as shown at step  54 . The method includes sensing the pH of the first foodstuff at step  55  for use in controlling the combination of the two foodstuff streams. 
     Providing the second foodstuff includes pumping foodstuff from the initial supply as shown at step  56  in FIG.  2 . This pumping step is performed using second pump  21  shown in FIG.  1 . It will be appreciated that the two streams of foodstuff may not be taken from a common supply as shown in FIG.  1 . The second foodstuff shown as stream B in FIG. 1 may be material which is not pH modified, or which is under modified. In any event, the second foodstuff has a pH which is opposite to a desired or target pH level with respect to the pH of the first foodstuff. Where the pH of the first foodstuff is higher than desired, the pH of the second foodstuff is lower than the desired, target pH level, and where the pH of the first foodstuff is lower than desired, the pH of the second foodstuff is higher than the target level. 
     The proportion at which the stream of first foodstuff and stream of second foodstuff is combined at step  58  depends upon the pH of the first and second foodstuffs and the desired fmal pH. FIG. 2 shows a single proportion control step  59 . This control step may include controlling the flow rate of the first foodstuff in stream A in FIG.  1  through first pump  20 . The control step may also or alternatively include controlling the flow rate of the second foodstuff in stream B in FIG.  1  through second pump  21 . FIG. 2 also indicates that the control step may include controlling the addition of pH modifying material through contactor  24 . For example, the control step may include modifying the pressure at which pH modifying material is supplied to contactor  24 , or the flow rate of pH modifying material into the contactor. 
     FIG. 2 also shows mixing step  61  after combining step  58 . This mixing may be performed as a separate step by a separate mixer such as mixing device  36  in FIG. 1, or by a mixing arrangement included in combiner  14 . The purpose of the mixing at step  61  is to thoroughly blend the first and second foodstuffs together to form the third foodstuff having the target uniform pH. The pH of this third foodstuff may be checked at step  62  in FIG. 2 to ensure the desired pH level has been obtained 
     Although the invention is described above with reference to a continuous pH modifying process, the method of the invention as defined in the following claims is not limited to a continuous process. The first and second foodstuffs may simply be combined together in a single batch and then mixed to produce a final mixed foodstuff having the target pH. Also, the pH modified foodstuff such as the material exiting pH modifying arrangement  12  in FIG. 1 need not be combined immediately with the second foodstuff. Rather, the first or pH modified foodstuff may be packaged and shipped to a remote mixing facility where it is combined and mixed with the second foodstuff in the proportion required to produce the target pH. 
     The preferred form of the invention utilizes an over-ammoniated foodstuff as the first foodstuff and an untreated foodstuff as the second foodstuff. The first foodstuff may be over ammoniated to raise the pH of the material over 7 to as much as 10.5, but preferably between 7.0 and no more than approximately 9.5. For example, a communicated meat product such as lean finely textured beef “LFTB” may be over ammoniated to a pH of 9.0 and mixed in a 1 to 1.3 ratio by weight with ground beef at a pH of 5.5 to produce a mixed product (43% LFTB and 57% ground beef) having a pH of approximately 7. A lower pH in the LFTB would allow a higher percentage of LFTB to be used with ground beef in the mixed product to produce a mixed product having the desirable pH of approximately 7. As another example, LFTB over ammoniated to a pH of 8.0 may be mixed in a 1 to 7 ratio by weight with ground beef at a pH of 5.5 to produce a mixed product (59% LFTB and 41% ground beef) having a 7 pH. 
     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.

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