Abstract:
The present invention is directed to methods and apparatuses for processing food products and utilizes a series of guides for moving platens through several operative zones to press a food product intermediate. In particular, the present invention relates to an apparatus and method for forming generally flat dough products such as tortillas, taco shells, snacks and the like by gradually pressing a dough intermediate between movable platens that are disposed on concentric, endless belts.

Description:
TECHNICAL FIELD 
   The present invention relates generally to an apparatus and methods for forming food products. In particular, the present invention relates to an apparatus and method for forming generally flat dough products such as tortillas, taco shells, snacks and the like by gradually pressing a dough intermediate between movable platens that are disposed on concentric, endless belts. 
   BACKGROUND OF THE INVENTION 
   A wide variety of processes are known for forming dough intermediates into final products. Examples of such products include tortillas, pizza crusts, pie crusts, pastries, and cookies as well as snack products, including chips or crisps and fruit snacks. 
   It is widely recognized that many aspects of the manufacturing processes can have a substantial impact on the price that a consumer pays for the product. Usually, the cost of a product decreases in proportion to an increase in the speed with which the product can be fabricated. Additionally, process improvements that simplify the associated equipment may lead to decreases in the costs of obtaining and operating such equipment. 
   In the manufacture of flat products such as tortillas, piecrusts, snack products, and the like efforts have been increasingly directed toward reducing costs and increasing the speed of production. Traditionally, several manufacturing techniques have been utilized for economically and quickly forming tortillas on commercial production lines. A first popular method is known as die-cutting and a second popular method is known as pressing, both of which are described below. 
   In the die-cutting technique, tortilla dough is first formed in a commercial mixer. The dough is then transferred to an extruder that extrudes a sheet of dough onto a conveyor belt of a rolling and cutting machine to form a dough ribbon. In this step, the dough ribbon is gradually reduced to a predetermined thickness by sheeting and cross-rolling. 
   Once the dough has reached a desired thickness, a die is actuated to cut the dough into the desired form. The formed dough products are then separated from the remaining matrix and are moved to an oven where they are cooked. The matrix is usually returned to the extruder for reprocessing. 
   Several problems and limitations exist with the die-cutting method described above. One such problem is that the remaining matrix is often coated with flour prior to cutting to prevent the die from sticking to the dough. When this dough and flour is reprocessed, the extra flour and floor time can produce undesirable properties within the dough. For example, the flour can inhibit re-mixing, causing the subsequently processed dough product (e.g. tortilla) to be substantially inflexible or brittle, and may produce an undesirable taste in the product. 
   In addition, having the dough products produced by this method usually has a rheoligical bias in the direction of sheeting. That is, the tortilla will crack when folded in the direction that is transverse or perpendicular to the direction of the sheeting. Moreover, the sheeting process described above does nothing to seal the surface of the dough. Sealing the surface of the dough traps leavening gasses during baking which has been found to improve final bake quality of the product. 
   As mentioned above, a second common process for forming tortillas is by pressing, which is also referred to as the hot press method. In practice, dough balls are formed, proofed, and fed onto a conveyor that carries several dough balls at a time into position between the heated platens (up to 450° F.) of a tortilla press. Such relatively high temperatures must be imparted to the tortillas by the platens to overcome the inherent elastic tendency of the dough to snap-back after pressing. In other words, without sufficiently heating the dough, the tortillas will typically thicken and shrink in size, snap back or return to its original size. In addition, dough properties can vary from batch to batch, and may also vary significantly within a single batch. This creates further problems in providing a consistent and uniform product from a consumer standpoint. 
   In the pressing process, a batch of dough balls are positioned between heated press platens, the conveyor is then stopped and the press is closed compressing the balls into circularly shaped tortillas that are then transferred into an oven for baking. Using this method, the tortillas may be formed at reasonable production speeds, however, the time required for opening and closing the press and indexing the belt carrying the dough severely limits production to about 14 to 16 strokes per minute. 
   In addition, to limited production speeds, this method suffers from other drawbacks. For example, the individual components are more expensive when compared with a die cutting operation. Moreover, the intermittent movement and engagement of the platens adds further complexity to the system. Additionally, alignment of the dough balls with the press platens increases the difficulty in operating the equipment and may contribute to other problems, such as, misalignment which can lead to the tortillas being irregular or have a non-uniform thickness, such that they are not of an acceptable quality. 
   What is needed therefore, is an apparatus that overcomes the difficulties set forth above and which can process flat dough products in an efficient manner while maintaining consistently good, quality products. 
   SUMMARY OF THE PRESENT INVENTION 
   The present invention overcomes the disadvantages and shortcomings of the prior art by providing methods and apparatuses for forming substantially circular, planar dough products at commercially acceptable speeds while having a consistent and repeatable quality. 
   In one aspect of the present invention, an apparatus for forming a pressed food product from a dough intermediate is described and includes pressing the intermediate between first and second platens. In this embodiment, the apparatus includes a support frame that has first and second guides that are supported and positioned by the frame and are used to guide the first and second platens into position. The first and second guides further include a region where the first guide converges with the second guide and a second region where the first guide is substantially parallel to the second guide. The first guide is used to position the first platen and the second guide positions the second platen as the platens move through the converging region. The first and second platens converge together so that a dough intermediate which is disposed between the platens may be effectively pressed. The first and second platens may be substantially parallel to one another and are usually separated by a predetermined spacing as the platens move through the parallel region. The predetermined spacing generally corresponds to the desired thickness of the pressed dough product to be produced. 
   A method of forming a food product in accordance with the present invention is also described and may include the steps of initially moving a food product intermediate in a machine or first direction, and then moving a first platen in a direction generally towards a second platen, so as to be able to contact the food product intermediate. The first platen is disposed in an opposite position to the second platen so that the platens generally converge with one another in the direction of travel of the endless belts. As the first and second platens move through the converging region, the first platen and second platens converge to compress the food product intermediate to a desired thickness thereby forming a pressed food product, such as a tortilla, pizza crust, piecrust, snack product or the like. 
   In an additional aspect of the present invention, the above method may further include the step of moving the first and second platens through a second parallel region that holds the food product between the platens. The parallel region extends a predetermined length in the direction of travel of the endless belts. The first platen generally opposes the second platen and the platens are desirably parallel to one another and spaced apart a distance that corresponds to a desired thickness of the pressed food product. 
   In another aspect of the present invention, a method for reducing the thickness of a sheet of dough product is described and may include the steps of initially providing a sheet of dough that has an initial thickness; then directing a first and second movable endless belts toward one another so as to engage the sheet of dough. The sheet of dough has generally opposing surfaces. The movable endless belts each include a contact surface such that the contact surfaces of the endless belts converge with one another in a first region. The engagement step includes the contact surfaces of the endless belts contacting the opposing surfaces of the dough which the dough travels through the apparatus. That is, the endless belts converge to compress the dough product to form a dough product that has a thickness which is generally less than the initial thickness of the dough. 
   In yet another aspect of the present invention, the above method for reducing the thickness of a sheet of dough may additionally include the step of moving the first and second endless belts through a parallel region while the sheet of dough is disposed between the contact surfaces of the endless belts. In the presently described embodiment, the parallel region extends a predetermined length in the machine direction. In addition, the contact surfaces of the endless belts generally oppose one another and are disposed a predetermined distance apart. 
   In accordance with other elements of the present invention, the platens, belts or other contact surfaces of the apparatus may be heated or apply heat to the food product being processed. 
   These and other features and advantages of the present invention will be apparent in the following detailed description of the preferred embodiments when read in conjunction with the accompanying drawings, in which like reference numerals are used to identify the same or similar parts in the several views. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the present invention and together with the description of the preferred embodiments, serve to explain the principles of the invention. A brief description of the drawings is as follows: 
       FIG. 1  is a schematic side view of a food product processing system in accordance with the present invention showing upper and lower guides for guiding upper and lower belts having interconnected platens; 
       FIG. 2  is a partial side view of a positioning device in accordance with the present invention for adjustably positioning the upper guide with respect to the lower guide; 
       FIG. 3  is a partial schematic top view of the processing system of  FIG. 1  showing in particular a belt having interconnected platens, a pair of drive chains and sprockets for the belts and drive chains in accordance with the present invention; 
       FIG. 4  is a partial schematic side view of the processing system of  FIG. 1  showing in particular a converging region and a parallel region in accordance with the present invention; 
       FIG. 5  is a partial cross-sectional view of the processing system of  FIG. 1  showing in particular multiple dough intermediates entering the converging region of the processing system in accordance with the present invention; 
       FIG. 6  is a partial cross-sectional view of the processing system of  FIG. 1  showing in particular multiple dough intermediates which are partially compressed in accordance with the present invention and which are within the converging region; 
       FIG. 7  is a partial cross-sectional view of the processing system of  FIG. 1  showing in particular multiple dough intermediates which are fully pressed in accordance with the present invention and which are within the parallel region; 
       FIG. 8  is a schematic side view of a device for reducing the thickness of a sheet of dough in accordance with the present invention and showing in particular a converging region; and 
       FIG. 9  is a schematic side view of a device for reducing the thickness of a sheet of dough product in accordance with the present invention and showing in particular a parallel region. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention. 
   The present invention is directed to apparatuses and methods for processing food products. In particular, the present invention is directed to apparatuses and methods for processing food product such as dough based products and for pressing such dough based products to a desired shape and/or thickness. 
   With reference to the Figures, one embodiment of a food product processing system  10  is illustrated in  FIG. 1 . The processing system  10  comprises an upper guide  12  and a lower guide  14  both of which are supported by a frame  16 . The frame  16 , as shown, includes a first upright support member  17 , a second upright support member  19 , and a horizontal frame member  21 . It is contemplated, however, that the frame  16  may include additional or different frame members to achieve the functional aspects of the present invention. Also, the processing system  10  includes additional upper and lower guides not visible in  FIG. 1  that are similar to and generally spaced apart from the upper guide  12  and the lower guide  14  and which are positioned on the other side of the processing system  10 . The functional aspects of the upper guide  12  and the lower guide  14  are described in greater detail below. 
   As can be seen in  FIG. 1 , the upper guide  12  may be adjustably positioned with respect to the lower guide  14  by a first positioning device  18  and a second positioning device  20 . Alternatively, the upper guide  12  may be permanently mounted with respect to the lower guide  14  by any suitable structure. As shown in  FIG. 1 , the first positioning device  18  and the second positioning device  20  are spaced apart and positioned generally at opposite ends of the processing system  10 . Additional positioning devices may be utilized depending upon the application. 
   The processing system  10  preferably includes an upper belt  44  comprising a plurality of interconnected platens  46  and a lower belt  48  comprising a plurality of interconnected platens  50 . In one embodiment, the platens  46  and  50  are connected by way of a bracketed roller chain to form the upper belt  44  and the lower belt  48  respectively. The platens may also be connected by using at least one cable (not shown). In addition, a spring or tension controlling device may be included at a position between the interconnected ends of a cable for regulating changes in tension that may occur in a cable during driving of an interconnected belt of platens through the system. 
   The platens  46  and  50  may be interconnected by any suitable means such as by using hinges, wires or cables, links, or any such structure or device such that a continuous belt of interconnected platens is formed. Further, the upper belt  44  and the lower belt  48  may comprise continuous bands or belts such as are shown and described with respect to  FIGS. 8 and 9  below. 
   In accordance with the present invention, the platens  46  and  50  preferably have a flat outwardly facing surface for pressing a food intermediate such as a tortilla or the like, can be seen in  FIG. 4 . As shown, the platens  46  have a generally flat or planar pressing surface  47  and the platens  50  have a similar pressing surface  51 . In an aspect of the present invention, it is contemplated that one or both of the platens  46  and  50  may contain cavities for shaping food products such as by a molding process. For example, the platens  50  may contain a recessed shape for forming a shaped food product such as a cookie product, pie shell, or the like. Accordingly, a food product having a profile generally corresponding to the recessed shape may be formed. 
   Turning to  FIG. 2 , the upper guide  12  preferably includes a portion  22  which extends outward from a surface  23  of the upper guide  12  and the lower guide  14  also include a similar portion  24  which extends outward from a surface  25  of the lower guide  14 . In order to support the upper guide  12  with respect to the lower guide  14 , a threaded rod  26  passes through the portion  22  and the portion  24  and an end  28  of the threaded rod  26  may be secured within the frame member  19  as can be seen in  FIG. 2 . The frame member  19  may be any suitable frame member. 
   As shown in  FIG. 2 , the positioning device  20  further comprises nuts  32 ,  34 ,  36 , and  38  for securing and positioning the upper guide  12  and the lower guide  14  with respect to the threaded rod  26 . Threaded rod  26  may be threaded into frame member  19 , as shown in  FIG. 2 , and secured by nut  38 . The nut  34  may be used to set a predetermined spacing between a guide surface  40  of the upper guide  12  and a guide surface  42  of the lower. 
   In  FIG. 3 , a schematic partial top view of the processing system  10  of  FIG. 1  is illustrated. In  FIG. 3 , sprockets  52  and  54  are shown operatively connected to axle  56  and sprockets  58  and  60  are shown operatively connected to axle  62 . As can be seen in  FIGS. 1 and 3 , the sprockets  52 ,  54 ,  58 , and  60  are preferably used to carry the belt  44  having the platens  46  such as through the use of a drive chain or the like. Sprockets  64  and  66  are illustrated for carrying the lower belt  48 . Additional sprockets corresponding to those described with respect to the upper belt  44  are preferably used for carrying the lower belt  48  but are not visible in  FIG. 1 . As such, it is noted, in this embodiment that the arrangement of the lower belt  48  and its corresponding sprockets is similar to the arrangement of the upper belt  44  and its corresponding sprockets. The arrangement of the lower belt  48  and the upper belt  44  may, however, be different. 
   Sprockets  52 ,  54 ,  58 ,  60 ,  64 , and  66  illustrated schematically in  FIGS. 1 and 3 . It should be understood that the assembly of sprockets  52 ,  54 , and the axle  56  as well as the assembly of sprockets  58 ,  60 , and the axle  62  may be mounted to the upper guide  12  or to a suitable frame member. It is further contemplated that the arrangement of sprockets  64  and  66  and the corresponding sprockets and axles which are not illustrated may be mounted to the lower guide  14  or to a suitable frame member. Additionally, the frame  16  of the processing system  10  may preferably include additional frame members for providing operative support for any of the arrangements of sprockets and axles described above. 
   As provided in  FIG. 3 , sprockets  68  and  70  are mounted on axle  56  and sprockets  72  and  74  are mounted on axle  62  for carrying drive belt  76  and drive belt  78 . That is, sprockets  68  and  72  carry the drive belt  76  and sprockets  70  and  74  carry the drive belt  78 . Drive belts  76  and  78  comprise roller chains having links  86 . Referring back to  FIG. 1 , sprockets  80  and  82  are illustrated for carrying drive belt  84 . Also, sprockets similar to sprockets  68  and  72  are positioned on axles  140  and  142  for carrying a drive belt similar to drive belt  76  (not shown). 
   In the present embodiment, the platens are attached by brackets to a roller chain driven by sprockets  52  and  58 , on one side of the apparatus and sprockets  54  and  60  on the other side of the apparatus. The roller chains listed as items  76  and  78  may be fixed to the platens or may be free or floating. As such, the guides dictating the travel of the platens  12  and  14  in  FIG. 1  may be of different design depending on the exact nature of the roller chain and its relationship to the platens. 
   Referring to  FIG. 1 , the processing system  10  preferably includes an upper tensioner  88  and a lower tensioner  90 . The upper tensioner  88  can be used to place the drive belt  78  and the belt  44  under a predetermined amount of tension in order to achieve the necessary motive force for the invention and to compensate for thermal expansion. 
   As can be seen in  FIG. 1 , the drive roller chain  78  preferably foms a continuous loop and is carried by sprockets  70  and  74  and may be guided by the upper guide  12  and the upper support  101 . The platens are fixed to drive roller chains  78  and  84  and the drive chain is drive by brackets. 
   Also in  FIG. 1 , the drive chain  84  forms a continuous loop and is carried by sprockets  80  and  82  and may be guided by the lower guide  14  and the platen support carrier  102 . The platens are bolted to drive roller chains  78  and  84  by brackets. On a wide machine, there may be several drive rollers chains across the width of the machine as just described to carry the compression load. In another embodiment, only the outer roller chains may be fixed to the platens while the inner roller chains may be free floating. As such, the inner roller chains may follow inner roller chain guides with a different design to account of the height difference of the roller chain. 
   Further referring to  FIG. 1 , the processing system  10  preferably includes an upper belt  100  carried by pulleys  104 ,  106 ,  108  and  110  and a lower belt  102  carried by sprockets  112 ,  114 ,  116  and  118 . At least one of the sprockets  104 ,  106 ,  108 , and  110  may be driven for driving the belt  100  through the processing system  10 . As above, at least one of the sprockets  112 ,  114 ,  116 , and  118  is driven for driving the belt  102  through the processing system  10 . 
   In addition to compression forces, heat may also be applied to the food product being processed by the processing system  10  by heating the platens  46  and  50 . As an example, the material for the belts  100  and/or  102  may be chosen such that the heat transfer rate between the platens can be modified if needed. For example, the belts  100  and/or  102  may have portions or regions that are open or perforated to differentially control the heat transfer rate between the platens and the food product. For certain food products this may advantageously provide greater control over the post-processed characteristics of the food product. That is, certain food products, if heated too rapidly, may develop undesirable surface toughness or other undesirable features. 
   The belts  100  and/or  102  may also have a nonstick surface so that food product will not stick to the surface. One preferred nonstick material for the belts  100  and/or  102  is Teflon®, however, other nonstick materials, such as silicone, or the like may be used. 
   The processing system  10  includes an upper heater  120  and a lower heater  122  which are illustrated schematically in  FIG. 1 . In one aspect of the present invention, the upper heater  120  can be used to heat the platens  46  of the belt  44  and the lower heater  122  can be used to heat the platens  50  of the belt  48 . The heaters  120  and  122  may comprise any conventional device such as electric or fuel fired radiant heaters or may utilize a convective heat transfer mechanism such as by using forced air to heat the platens  46  and  50  respectively. Further, it is understood that the heaters  120  and  122  may be connected to sensors (not shown) for measuring the temperature of the platens  46  and  50 . For example, sensors such as thermocouples or infrared sensors may be positioned with respect to the platens  46  and  50  in order to measure the temperature of the platens  46  and  50 . Additionally, the sensors may be utilized in combination with a control system capable of providing feedback to the heaters  120  and  122  for adjustably controlling the temperature of the platens  46  and  50 . As such, accurate temperature profiles may be provided for processing food products having different requirements. In certain applications, either or both of the platens  46  and  50  may be cooled rather than heated as described above. 
   In  FIG. 4 , a schematic view of a portion of the processing system  10  is illustrated showing in particular a converging region  124  and a parallel region  126 . The converging region  124  functions as a pressing region and the parallel region  126  functions as a holding and or baking or sealing region for processing food product. The lower guide  14  has a guide surface  128  for guiding the drive belt  84 , which is a roller chain having rollers  130 . The platens  50  of the belt  48  are driven in a direction A (the machine or first direction). Further referring to  FIG. 4 , the upper guide  12  includes a converging guide surface  132  and a parallel guide surface  134  for guiding the drive chain  78 . The drive chain  78  preferably comprises a roller chain having rollers  136 . 
   As the belt  44  and the belt  48  are driven in direction A, the platens  50  of the belt  48  follow the guide surface  128  of the lower guide  14 . In an exemplary embodiment, the platens  50  follow a substantially horizontal path. This is generally preferred as the dough  144  may be introduced to the processing system  10  by being placed on the belt  102  at a loading region  138  of the processing system  10  as is shown in  FIG. 1 . The horizontal path for the platens  50  provides positionally stability for the food product as the food product enters the converging region  124 . Further, as the belt  44  and the belt  48  are driven in the direction A, the platens  46  of the belt  44  may follow the converging surface  132  and may converge towards the platens  50  of the belt  48 . 
   In the present embodiment, the converging guide surface  132  may be formed such that it has a radius, R, of about 40 feet (see  FIG. 4 ). Such a guide surface approximates a roller having a diameter of about 80 feet. By using such a large radius for the converging guide surface  132  this provides for gradual compression of a food product as the platens  46  and  50  move through the converging region  124  in direction A. By gradually compressing the food intermediate it has been found that such a process generally requires less force when compared with faster pressing methodologies typically utilized in conventional food product presses. That is, the present invention may provide increased compression time overall while providing gradual compression of the food product as it is pressed, thereby reducing stress on the dough. 
   The exemplary operative driving motion of the processing system  10  is described with reference to  FIGS. 1 and 3 . The upper drive system for driving the upper belt  44  having the platens  46  includes sprockets  54  and  70  mounted on common axle  56  opposite from sprockets  68  and  52 , and sprockets  60  and  74  mounted on common axle  62  opposite from sprockets  72  and  58 . The upper drive system further includes drive belt  78 , which is carried by sprockets  70  and  74  and drive belt  76  which is carried by sprockets  68  and  72 . Sprockets  52 ,  54 ,  58 , and  60  each include an over-running clutch (not shown), which allows the sprockets  52 ,  54 ,  58 , and  60  to controllably slip with respect to the sprockets  68 ,  70 ,  72 , and  74 . In  FIG. 1 , the lower drive system for driving the lower belt  48  having the platens  50  includes sprockets  64  and  80 , which are mounted on common axle  140 , and sprockets  66  and  82 , which are mounted on common axle  142 . The lower drive system further includes the drive belt  84 . Sprockets  64  and  66  each include an over-running clutch (not shown), which allows the sprockets  64  and  66  to controllably slip with respect to the sprockets  80  and  82 . Additionally, the lower drive system includes similar sprockets (not shown) mounted on axle  140  opposite from sprockets  64  and  80  and includes similar sprockets mounted on axle  142  opposite from sprockets  66  and  82 . The lower drive system also includes an additional drive belt (not shown), which is carried by the sprockets (not shown) opposite from sprockets  80  and  82 . 
   In an exemplary embodiment, the axles  56  and  140  each include a drive motor (not shown) and the axles  62  and  142  are not driven. Under operating conditions where no food product is being processed by the processing system  10 , the sprockets  54  and  64  preferably drive the platens  46  and  50  in direction A ( FIG. 1 ). In such operation, the drive belts  78  and  84  move without providing substantial driving force to the platens  46  and  50 . That is, the drive belts do not frictionally engage the platens as they do when food product is being processed by the system  10 . This is because the tensile load on the link between the platens is generally low when no food product is being processed. 
   Under operating conditions where the system is processing food product, that is, where food product is being compressed between the platens  46  and  50 , it is preferred for the drive chain  78  to provide additional driving force to the platens  46  and  50  by frictionally engaging with the platens  46  and  50 . This is because the tensile forces on the interconnected platens  46  and  50  of the belts  44  and  48  may become generally too large for the sprocket  54  to provide reliable drive motion to the platens  46  and  50  when food product is being compressed between the platens  46  and  50 . Also, the interconnected platens may have a variable velocity as the platens hinge around the respective platen sprockets, especially for a generally wide platen and correspondingly small sprocket. This is sometimes referred to as “chordal action” with respect to a driven chain having interconnected links. 
   In operation, the processing system  10  may be utilized to form a generally flat food product, such as a tortilla taco shells, snacks and the like. A dough intermediate  144  may be introduced to the processing system  10  at a loading region  138  as is illustrated in  FIG. 1 . The dough intermediate is loaded onto a nonstick surface such as the belt  102  described above. In operation, the driving motion of the system conveys the dough intermediate in direction A such that it may enter the converging region  124  as is illustrated in  FIG. 4 . 
   In  FIG. 5 , the processing system  10  is shown in partial cross-section according to the present invention. The upper guide  12  and the lower guide  14  are shown guiding the rollers  136  and  130  and the platens  46  and  50 , respectively. Additionally, an upper guide  13  and a lower guide  15  are shown guiding rollers  137  and  133  and the platens  46  and  50 , respectively. In this figure, the belts  100  and  102  are illustrated and dough intermediates  146  and  148  are shown on belt  102  just prior to entering the converging region  124 . 
   Referring to  FIG. 6 , the dough intermediates  146  and  148  are shown partially compressed as they begin moving through the converging. That is, the platens  46  and  50  are guided by the upper guide  12  and the lower guide  14  such that the dough intermediates  146  and  148  are pressed between the platens  46  and  50 . 
   In  FIG. 7 , the dough intermediates  146  and  148  are shown in the parallel and are fully pressed to at a predetermined thickness. 
   For certain applications, the platens  46  and  50  may be heated, to minimize elastic snap back of the pressed dough. In the present embodiment, the dough intermediate  146  and  148  pass through the parallel region  126  while being heated or sealed by the platens  46  and  50 . Alternatively, the parallel region  126  may function as a holding region to maintain or hold constant pressure and temperature. Accordingly, heat may be applied to a pressed dough product for a generally long period while maintaining a continuous manufacturing process. A generally longer hold time is advantageous in that a lower temperature may be used. 
   In an embodiment of the present invention, the processing system  10  may also be used as a dough proofing system. In such a proofing operation, dough may enter the parallel region  126  and be heated by the platens  46  and  50  as it moves through the zone. Such a heating method is advantageous in that the thermal transfer rate between the heated platens in contact with the dough products would be significantly higher than the heat transfer rate obtainable through thermal or convective heating such as in a conventional oven or the like. As such, the present invention may advantageously provide a generally faster and more efficient proofing system, without drying out the dough when compared with a forced air environment such as a conventional convective type proofing system. 
   In another aspect of the present invention, the processing system  10  may be used for sheeting and/or post-sizing of food products such as snacks, piecrusts, pizza crusts, pastries, pita breads, crackers, masa products and the like. Accordingly, the processing system  10  may comprise continuous endless belts or bands that provide gradual compression of a dough intermediate described above and shown schematically in  FIG. 1 . 
   In accordance with the present invention, a schematic illustration of a device  198  for reducing the thickness of a sheet of dough product  200  while minimizing dough tearing and providing improved surface characteristics at relatively high processing speeds is shown in  FIGS. 8 and 9 . 
   In  FIG. 8 , the dough intermediate  200  has an initial thickness  202  and a reduced thickness  204 . Also, the sheet of dough product  200  generally has a first surface  206  and a second surface  208 . As shown the dough intermediate  200  may be gradually compressed from the initial thickness  202  to the reduced thickness  204  as the dough moves in direction B by a first wedge roller device  210  and a second wedge roller device  212 . The first wedge roller device  210  comprises a continuous endless belt  214  having a contact surface  216  which may contact and engage the first surface  206  of the sheet of dough product  200 . Likewise, the second wedge roller device  212  comprises a continuous endless belt  218  having a contact surface  220 , which contacts and engages with the second surface  208  of the sheet of dough product  200  as shown. 
   As can be seen in the exemplary schematic embodiment of  FIG. 8 , the first wedge roller device  210  further includes rollers  222 ,  224 , and  226  for supporting and carrying the continuous endless belt  214 . At least one of the rollers  222 ,  224 , and  226  is a driven roller for driving the continuous endless belt  214 . The roller  226  may provide a tensioning function for adjustably controlling the tension in the continuous endless belt  214  of the first wedge roller device  210 . The second wedge roller device  212  further includes rollers  228 ,  230 , and  232  for supporting and carrying the continuous endless belt  218 . At least one of the rollers  228 ,  230 , and  232  is a driven roller for driving the continuous endless belt  218 . As above, the roller  232  may provide a tensioning function for adjustably controlling the tension in the continuous endless belt  218  of the second wedge roller device  212 . 
   Further referring to  FIG. 8 , the continuous endless belt  214  of the first wedge roller device  210  is supported and positioned at an angle α with respect to the first surface  206  of the dough  200  and the continuous endless belt  218  of the second wedge roller device  212  is supported and positioned at an angle β with respect to the second surface  208  of the dough  200 . The preferred arrangement of the first wedge roller device  210  and the second wedge roller device  212  forms a converging region generally indicated by reference numeral  233 . Such a converging region may advantageously provide for relatively gentle compression (as compared to that of conventional rollers) of the dough and generally reduce accumulation of elastic stress, especially at generally high processing speeds. The distance between the rollers  224  and  230  as well as the magnitude of the angles α and β are adjustably controllable for use with different dough product processing requirements and applications. Furthermore, the angles α and β may be empirically determined for a particular application. That is, the angles α and β may be derived from observations of the actual operation of the wedge roller devices. 
   Now referring to  FIG. 9 , a schematic illustration of a device  234  similar to the device  198  shown in  FIG. 8  and described above is illustrated. In general, as described below, the device  234  includes a converging region  274  similar to the converging region  233  of the device  198  and additionally includes a parallel region  276 . The device  234  includes a first wedge roller device  236  and a second wedge roller device  238 . The first wedge roller device  236  has a continuous endless belt  240  with an outer or contact surface  242  and the second wedge roller device  238  includes a continuous endless belt  244  having an outer or contact surface  246 . Also, the first wedge roller device  236  includes rollers  248 ,  250 ,  252 , and  254  for carrying the continuous endless belt  240  and the second wedge roller device  238  includes rollers  256 ,  258 ,  260 , and  262  for carrying the continuous endless belt  244 . As above with respect to the device  198  shown in  FIG. 8 , at least one of the rollers  248 ,  250 ,  252 , and  254  of the first wedge roller device  236  and at least one of the rollers  256 ,  258 ,  260 , and  262  of the second wedge roller device  238  is a driven roller for driving the continuous endless belts  240  and  244  of the first and second wedge roller devices  236  and  238  respectively. 
   Further referring to  FIG. 9 , a sheet of dough product  264  having an initial thickness  266  and a reduced thickness  268  is shown and is prepared in a manner similar to that as described above. 
   As, illustrated in  FIG. 9 , the portion of the continuous endless belt  240  between the rollers  252  and  254  is supported and positioned to be generally parallel to direction C while the portion of the continuous endless belt  240  between the rollers  248  and  252  is supported and positioned to be at the angle α′ with respect to the portion of the continuous endless belt  240  between the rollers  248  and  252 . Similarly, the second wedge roller device  238  a similar arrangement of rollers having a continuous endless belt  244  between the rollers  260  and  262 , which is supported and positioned to be generally parallel to direction C while the portion of the continuous endless belt  244  between the rollers  256  and  260  is supported and positioned to be at the angle β′ with respect to the portion of the continuous endless belt  244  between the rollers  260  and  262 . 
   The arrangement of the first wedge roller device  236  and the second wedge roller device  238  provides the converging region (rollers  248 ,  252 ,  256 , and  260 ) generally indicated by reference numeral  274  and the parallel region (rollers  252 ,  254 ,  260 , and  262 ) generally indicated by reference numeral  276 . As above, with respect to the device  198  shown in  FIG. 8 , the distance between the rollers  252  and  260  and the rollers  254  and  262  as well as the magnitude of the angles α′ and β′ are preferably adjustably controllable for use with different dough product processing requirements and applications. 
   The device  234 , shown and schematically illustrated in  FIG. 9 , may be advantageously used to reduce the dough  264  from the initial thickness  266  to the desired final thickness  268 . The dough  264  may be supplied to the processing device  234  by, for example, a suitable conveyor or transport mechanism such that the sheet of dough product  264  may enter the converging region  264 . As the dough  264  enters and moves through the converging region  264 , the contact surfaces  242  and  246  of the moving endless belts  240  and  244  may engage with the surfaces  270  and  272  of the dough  264  respectively. Such engagement may cause the sheet of dough product  264  to move in direction C as it moves through the converging region  274  such that the sheet of dough product  264  may be gradually compressed as illustrated in  FIG. 9 . Such gradual compression is advantageous in that less elastic stress may be formed in the sheet of dough product, as the compression profile may be generally less that that of conventional dough rollers. Thus, lower failures and defects such as dough tearing and poor surface qualities may be obtained at generally increased processing speeds. 
   As the sheet of dough product  264  exits the converging region  274 , the dough having the reduced thickness  268  may enter the parallel region  276 . The parallel region can allow any elastic stress in the compressed dough to relax such that processing speed may be increased with minimized dough failure and defects. 
   The present invention is not limited to the above described preferred apparatus and methods. More generally, the invention embraces gradual pressing and extended holding of food products to facilitate reduced elastic snap back and improved surface morphologies reduced dough sheet failures at high processing speeds. Furthermore, it should be understood that, while particular embodiments of the invention have been discussed, this invention is not limited thereto as modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Accordingly, the appended claims contemplate coverage of any such modifications as incorporate the essential features of these improvements within the true spirit and scope of the invention.