Abstract:
Disclosed is an improved system, method and apparatus for turning a bedded product to enhance the temperature uniformity of the product. In one aspect, the system is directed towards using a flow wheel to turn over a bed of hot product exiting a dehydrator. The improved system, method, and apparatus lowers the variability of temperature, moisture content, oil content and acrylamide levels in a bedded food product.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to an improved method for producing a fried food product having a reduced level of acrylamide variability. More specifically, the present invention relates to a method and apparatus to enhance product quality by lowering the variability of the temperature, moisture content, and acrylamide levels in a bedded food product exiting a dehydrator such as a deep fryer. 
         [0003]    2. Description of Related Art 
         [0004]    The chemical acrylamide has long been used in its polymer form in industrial applications for water treatment, enhanced oil recovery, papermaking, flocculants, thickeners, ore processing and permanent-press fabrics. Acrylamide precipitates as a white crystalline solid, is odorless, and is highly soluble in water (2155 g/L at 30° C.). Synonyms for acrylamide include 2-propenamide, ethylene carboxamide, acrylic acid amide, vinyl amide, and propenoic acid amide. Acrylamide has a molecular mass of 71.08, a melting point of 84.5° C., and a boiling point of 125° C. at 25 mmHg. 
         [0005]    In recent times, a wide variety of foods have tested positive for the presence of acrylamide monomer. Acrylamide has especially been found primarily in carbohydrate food products that have been heated or processed at high temperatures. Examples of foods that have tested positive for acrylamide include coffee, cereals, cookies, potato chips, crackers, french-fried potatoes, breads and rolls, and fried breaded meats. In general, relatively low contents of acrylamide have been found in heated protein-rich foods, while relatively high contents of acrylamide have been found in carbohydrate-rich foods, compared to non-detectable levels in unheated and boiled foods. 
         [0006]    It would be desirable to develop one or more methods of reducing the level of acrylamide in the end product of heated or thermally processed foods. Ideally, such a process should substantially reduce or eliminate the acrylamide in the end product without adversely affecting the quality and characteristics of the end product. 
       SUMMARY OF THE INVENTION 
       [0007]    The proposed invention provides a system, apparatus and method for making a fried food product having a reduced level of acrylamide, temperature, and moisture content variability. In one aspect, the invention is directed towards a turning apparatus comprising a plurality of rotatable blades wherein each rotatable blade has a flexible extension. In one aspect, the invention is directed towards a system for turning a bed of product comprising a flow wheel having a plurality of rotatable blades and a conveyor below the rotatable blades. In one aspect, the invention is directed towards a method for turning a bed of product on a conveyor by providing a trough, collecting the bed of product into the trough and rotating the trough. In one aspect, the invention is directed towards a method for turning a bed of fried products to minimize the temperature differential within the product by turning the bed of fried product over with a flow wheel. 
         [0008]    Other aspects, embodiments and features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. The accompanying figures are schematic and are not intended to be drawn to scale. In the figures, each identical, or substantially similar component that is illustrated in various figures is represented by a single numeral or notation. For purposes of clarity, not every component is labeled in every figure. Nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. All patent applications and patents incorporated herein by reference are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a side view of one embodiment of the present invention; 
           [0011]      FIG. 2   a - 2   c  is a temporal side view of the flow wheel in accordance with one embodiment of the present invention; 
           [0012]      FIG. 3  is a front perspective view of the flow wheel in accordance with one embodiment of the present invention; 
           [0013]      FIG. 4  is a top view of the fryer, outlet conveyor, and flow wheel in accordance with one embodiment of the present invention; 
           [0014]      FIG. 5  is a side view of the flow wheel in accordance with one embodiment of the present invention; and 
           [0015]      FIG. 6  is a side view of the flow wheel in accordance with an alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    An embodiment of the innovative invention will now be described with reference to  FIG. 1 . Whole potatoes stored in hopper  2  are dispensed into a slicing apparatus  4  which drops potato slices into a water wash  6 . 
         [0017]    The slices are removed from the water wash  6  by an endless belt conveyor  8  and deposited in frying oil contained within a fryer  10 . Because the present invention can be applicable to foods other than sliced potatoes, the invention will now be described generally as pertaining to food pieces. 
         [0018]    The frying oil entering the fryer is maintained at an initial temperature between about 320° F. to about 380° F. more preferably between about 335° F. and about 370° F. Any conventional frying medium can be used in accordance with various embodiments of the present invention, including frying mediums with digestible and/or non-digestible oils. In one embodiment, the fryer is a continuous single flow or multizone fryer which utilizes devices such as paddle wheels,  14 A and  14 B, and a submergible conveyor belt  16  to control the flow of food pieces through the fryer  10 . Once the potato slices or food pieces have been fried to a water content of less than about 3% by weight, the food pieces are removed from the fryer by a mesh endless belt conveyor  18 . The conveyor  18  typically runs at a speed of between about 1-inch to 2-inches per second. The fried food pieces can be routed by a higher speed conveyor  60  to a tumbler for seasoning. The seasoned food pieces can then be packaged and shipped. 
         [0019]    As shown by  FIG. 1 , the food pieces beneath the submerger  16  are typically in a bedded configuration  20  having a bed thickness  22 . In one embodiment, the bed thickness  22  is roughly about 6 inches. It has been surprisingly discovered that the location of a food piece in the bed  20  when in the fryer  10  is a factor in the acrylamide level of the fried food piece. The food pieces maintain their general elevational position as they navigate through the fryer  10  beneath the submerger  16 . Specifically, the food pieces at the bed bottom  24  typically stay at the bed bottom  24 , food pieces in the middle  26  of the bed typically stay in the bed middle  26  and the food pieces at the top  28  of the bed typically stay at the bed top  28  as the fried food pieces move through the fryer beneath the submerger  16 . 
         [0020]    A temperature gradient forms in the fryer oil from the bed top  28  to the bed bottom  24 ; the bed bottom  24  being warmer since it is adjacent to hot oil  12  and the bed top  28  being cooler because the bed top  28  food pieces are surrounded by product being cooled down by evaporating water. Additional heat flux is also provided to the bed bottom  24  because freshly heated hot oil  12  typically enters the fryer  10  at or near the bottom of the fryer. 
         [0021]    This temperature differential transfers to the bedded product  30  that has exited the fryer  10  and the fried food pieces on the bed bottom  34  of the exited bedded product  30  cool less than the fried food pieces on the bed top  38  for several reasons. First, because the bed bottom  34  fried food pieces are adjacent to the hot belt conveyor  18  having been heated by the hot oil, the heat from the conveyor  18  transfers to the bed bottom  34 . Second, the bed bottom  34  is not exposed to the cooler gaseous fluid that the bed top  38  fried food pieces are exposed too. Finally, the product in the bed middle  36  and the bed bottom  34  are insulated by adjacent fried food pieces. While dependent upon the conveyor  18  speed, the bed thickness  32  is usually similar to the bed thickness  22  beneath the fryer and is typically about 6 inches. These fried food pieces typically stay on the outlet conveyor for 45 to about 60 seconds. Consequently, the fried food pieces on the bottom of the outlet conveyor  18  have lower moisture contents and higher acrylamide levels than the fried food pieces on the top of the bed with a top to bottom temperature gradient. 
         [0022]    The bedded product  30  on the conveyor was tested at the bed bottom  34  the bed middle  36  and the bed top  38  for temperature and for levels of moisture content, and acrylamide. The averages of the samples are provided below: 
         [0000]                                          TABLE 1                   Positional average of temperature,       moisture content, and acrylamide levels.                    Temperature   Moisture Content   Acrylamide           Location   (° F.)   (% by weight)   (ppb)                       Top   222   1.47   509           Middle   263   1.32   617           Bottom   289   1.16   712                        
The above table demonstrates that the acrylamide level in a fried food product can be dependent upon the position of the fried food piece in the food product bed. Consequently, if the food pieces near the bottom  34  of the bed can be turned over after the product exits the fryer so that the food pieces can cool, the variation of the acrylamide concentration in the fried food pieces can be reduced because most of the acrylamide formation occurs at higher temperatures and lower moisture contents and turning the bed over provides more uniform cooling.
 
         [0023]    Turning over the bed of food product on the outlet conveyor has proven difficult because the fried food pieces comprising the bedded configuration  20   30  are made up of interlocking food pieces. When flat dough pre-forms or flat potato pieces are fried in hot oil, the pieces can curl during deep frying. Because so many potato pieces are in close proximity and concurrently curling during frying, the inventors have discovered that the food product bed  20  becomes interlocked in all three dimensions when the food pieces are fried beneath the submergers  16 . Consequently, when the bedded product  30  exits the fryer  10  on the outlet conveyor  18 , the bed of food pieces need to scooped up to be turned over, otherwise they will get backed up on the conveyor  18 . As an illustration of this difficulty, a beveled flat plate having a height comparable to the product bed, and a thickness 1/16-inches was placed in a stationary position longitudinally above the outlet conveyor  18  in an effort to divide the flow of bedded product  30  to guide a portion of the bedded product to a flow wheel having a length substantially less than the overall width of the conveyor. In another test, an attempt was made to push the plate into the bedded product by moving the plate toward the fryer. In both cases, the bedded product  30  did not divide, and because of the interlocking of the food pieces, the bedded product  30  was stopped by the beveled, flat plate and backed up on the conveyor  18 . Interestingly, if the plate was vibrated to loosen the bed and reduce the interlocking forces between the food pieces, the bed could be divided. 
         [0024]      FIG. 2   a - 2   c  is a temporal side view of the flow wheel  40  in accordance with one embodiment of the present invention. Referring to  FIG. 2   a,  in the embodiment shown, the flow wheel  40  comprises a plurality of rotatable blades  42 . In one embodiment, the blades  42  are concave in shape and form a trough  46  for holding food product. As the bedded product  30  is carried by the conveyor  18 , the flow wheel  40  rotates in the clockwise position. Because of the interlocking of bedded product  30 , the blades  42  in one test failed to pick up and turn over the bedded product  30  on a continuous basis because of a gap between the distal end of the blade  42  and the conveyor  18 . Rather, as the bedded product  30  engaged the distal end of the blade  42 , the blade  42 , as it was rotated slowly, initially was able to scoop in most of the bedded product  30 . However, at each subsequent rotation, the amount of bedded product  30  being scooped into the blades  42  decreased and the blades  42  eventually stopped scooping bedded product  30  because the bedded product  30  was interlocked. As a result, the bedded product backed up on the conveyor  18 . 
         [0025]    To solve this problem, in one embodiment, each blade  42  has a flexible extension  44  mounted about the entire width of the blade  42  on the distal end of the blade  42 . The flexible extension  44  is sized short enough in length to ensure that during its circular trajectory, the flexible extension  44  does not contact the conveyor  18  at an angle that could damage either the blade  42  or the conveyor  18  moving in the opposite direction. The flexible extension advantageously bends to become flat on the conveyor  18  and both the conveyor  18  and the blade  42  continue to move in the opposite direction without any gap between the conveyor  18  and the flexible extension  44 . While the flexible extension  44  is flat on the conveyor  18  and traveling in the opposite direction of the conveyor  18 , the bedded product  30  can be scooped into the trough  46 . Because of the flexibility of the extension  44 , the flow wheel  40  can be lowered towards the conveyor  18  so that there is no substantial gap between the distal end of the blade  42  and the bottom of the bedded product  30  to cause the bedded product  30  to back up. Without the flexible extension  44 , the distal end of the blade  42  can damage the conveyor  18 . In one embodiment, the flexible extension  44  comprises a length of between about ¼-inch and about 4-inches. Of course, such range is provided for purposes of illustration and not limitation. The flexible extension  44  can be made of DELRIN or other suitable material. 
         [0026]    Referring to  FIG. 2   b,  because the flexible extension  44  is substantially flat on the conveyor  18  and moving in the opposite direction of the conveyor  18 , the bedded product  30 , even if comprising interlocked product, can be collected into the trough  46 . If the bedded product  30  comprises interlocking food pieces, then use of a rigid blade  42  without the flexible extension  44  fails to collect the food pieces into the trough  46  because of the gap created between the distal end of the blade  42  and the conveyor  18  during the circular movement of the blade  42 . In one embodiment, the flexible extension  44  and/or the blades  42  are moving when being used to collect the bed of food product into the trough  46 . Such movement can provide a scooping action to collect the food pieces forming the bedded product  30  into the trough  46 . 
         [0027]    Referring to  FIG. 2   c,  as the flow wheel  40  rotates clockwise, the food product bed previously collected has been turned over and is discharged back onto the conveyor  18  as another load of product is collected. In one embodiment, the flow wheel  40  turns at a constant rotational speed. For example, the rotation of the flow wheel  40  can be timed to collect and turn product at the same rate as the product exits the conveyor  18 . In one embodiment, the flow wheel turns at a variable rotational speed. For example, it may be desirable for the flow wheel to turn at a faster or slower speed as the distal end of the blade and/or flexible extension  44  first contacts the product bed  30  to facilitate a scooping action and/or break the interlocking of the product bed. In one embodiment, the rotational speed of the flow wheel  40  can be manipulated such that the rotational speed accelerates after it has collected or scooped the bedded product  30  into the trough so that the blade  42  is not in the way of the next batch being continuously fed by the conveyor  18 . In one embodiment, the acceleration is followed by a deceleration during the scooping action. The rotational speed profile can also be configured to provide a vibratory/jerking motion to the flexible extension  44  or the distal end of the blade  42  to loosen the interlocked bedded product. For example, in one embodiment, the flow wheel  40  rotates back and forth slightly at a high frequency when the distal edge of the blade  42  or flexible extension  44  is about to contact the bedded product  30  to facilitate breaking up the interlocked bedded product  30 . 
         [0028]    Referring back to  FIG. 1  and  FIG. 2   c,  the turned over product bed  50  has a substantially sinusoidal shape. In one embodiment, the rotating flow wheel  40  turns the bedded product  30  over such that the top  38  fried food pieces are now on the bottom  58  of the product bed  50  exiting the flow wheel  40 . Similarly, the bottom  34  fried food pieces in the bedded product  30  entering the flow wheel  40  are disposed on the top  54  of the product bed  50  exiting the flow wheel  40 . Such turning over of the food product helps alleviate the temperature differential of product bed  50 . Thus, the bed bottom  24  food pieces having the warmest temperature in the fryer can be turned over and cooled much quicker due to the cooler gaseous fluid at the top  54  of the product bed  50 . Because acrylamide formation is not favored at lower temperatures, even at low moisture contents, the additional acrylamide formation that previously occurred because of the time (e.g., 45 seconds to 1 minute) the bottom of the bedded food product spent on the outlet conveyor does not occur in accordance with the present invention. 
         [0029]      FIG. 3  is a front perspective view of the flow wheel in accordance with one embodiment of the present invention. As shown in  FIG. 3 , the flow wheel  40  having a plurality of rotatable blades  42  can be mounted above the outlet conveyor  18  and can span substantially the entire width of the outlet conveyor. The blades  42  are sufficiently rigid so as to maintain their general shape while in operation. It should be pointed out that while the blades  42  are shown to be substantially parabolic and concave, such configuration is provided for purposes of illustration and not limitation. The blades on the flow wheel can be straight, arcuate, concave, shaped to hold product, shaped to form a trough, etc. The flexible extension  44  can be mounted about the entire width of the distal end of each blade  42 . In one embodiment, the flow wheel  40  comprises a diameter of about 18 inches. 
         [0030]      FIG. 4  is a simplified top view of the fryer  10 , outlet conveyor  18  and flow wheel  40  in accordance with one embodiment of the present invention. As shown by  FIG. 4 , guides  72  are used to direct the bed of food product towards the flow wheel  40 . Such guides  72  can be advantageous to move the bedded product  30  into the flow wheel  40  without causing the bedded product to back up on the conveyor  18 . The angle Θ should be minimized to ensure the bedded product  30  does not back up. Those having ordinary skill in the art, armed with this disclosure, will be able to determine the optimal angle Θ. 
         [0031]      FIG. 5  is a side view of the outlet conveyor  18  and flow wheel  40  in accordance with an alternative embodiment of the present invention. In the embodiment shown, a ramp  70  about the entire width of the flow wheel is provided in place of a flexible extension  44  to guide the bed of food product into the trough  46 . The top surface of the ramp  70  can be linear or curvilinear as desired. Because the ramp  70  raises the bedded product  30  and allows the distal edge of the blade  42  to be positioned just slightly below the ramp top  72 , the bedded product  30  can easily fall into the flow wheel trough  46  without causing any product backup. Because the conveyor  18  is moving the bedded product  30  towards the flow wheel  40 , the ramp  70  length and the ramp angle Φ should be minimized. Those having ordinary skill in the art, armed with this disclosure, will be able to ascertain the optimal ramp  70  dimensions. In the embodiment shown, the ramp  70  extends about the entire width of the conveyor. In an alternative embodiment, one or more guides  72  (shown in  FIG. 4 ) are used to directed product toward the ramp  70 . 
         [0032]    In one embodiment (not shown), the conveyor  18  itself is the ramp  70 . For example, a roller can be placed beneath the conveyor  18  and can extend about the width of the conveyor just prior to the flow wheel  40  to elevate a portion of the conveyor  18  about the width so that product can be collected into the trough  46 . In such embodiment, the ramp  72  is integral with the conveyor. Such embodiment can reduce the gap between the distal end of the blade and the conveyor across the entire width of the flow wheel. The raised contour of the conveyor can also provide easier transition of product into the trough. Use of a ramp may preclude the need for a flexible extension discussed above. 
         [0033]    Another potential problem with collecting bedded product  30  can occur if the conveyor sags about the width. For example, depending upon the width of the conveyor, the middle of the conveyor  18  can sag, preventing the flow wheel  40  from collecting bedded product  30  with a scooping action beneath the bedded product  30 . Consequently, in one embodiment, one or more support structures (not shown) can be placed beneath the conveyor  18  in the vicinity of the flow wheel  40  so that the elevation of the conveyor is constant along the width. Support structures can be a plurality of v-shaped members beneath the conveyor with the apex pointed downstream or transverse support structures such as a free rotating idler. Any support structure that prevents the conveyor from sagging can be used. 
         [0034]      FIG. 6  is a side view of the flow wheel in accordance with an alternative embodiment of the present invention. As shown in  FIG. 6 , the flow wheel  40  can be disposed between a first conveyor  18   a  and a second conveyor  18   b.  The flow wheel  40  can be positioned such that the distal end of the blade  42  is placed just slightly underneath the first conveyor  18   a  to permit the bedded product  30  to drop into the trough. The product can then be deposited back on the second conveyor  18   b.    
         [0035]    The present invention is able to reduce the temperature and moisture gradient in a bedded food product and can thereby reduce the variability of the acrylamide level of fried foods without sacrificing the organoleptical properties. Another advantage provided by the present invention is that the flow wheel permits oil to be drained from the food product as the food product is turned over. Such draining minimizes the potential for oil to accumulate at the bottom of the packed bed, and such accumulation can give rise to variability in oil content between the top and bottom of the bed. Consequently, the present invention advantageously also provides a way to minimize the oil variability in a packed bed. 
         [0036]    It should be pointed out that while some embodiments of the present invention are directed towards a potato slice embodiment; other embodiments can be used in accordance with the spirit and scope of the present invention. Consequently, where potato slices are referred to herein, Applicants mean to include any food product that continuously exits a dehydration medium with a temperature differential in the exiting product stream. Thus, while food product exiting a dehydrator in a bed is clearly within the scope of the present invention, food products exiting in a monolayered fashion can also be turned in accordance with the scope and intent of the present invention. For example, cookies or crackers can exit in a monolayered fashion, but can be on a hot conveyor that can create a temperature differential in that food product from top to bottom. Further, the present invention can also be applied to dough-based embodiments and fabricated food products including, but not limited to, corn chips and tortilla chips. For example, a corn chip or a tortilla chip exiting a fryer in a bedded configuration can be turned over in the same way as potato chips. Similarly, addition to fryers, the present invention can be used where hot food exits any dehydrator in a bedded configuration including, but not limited to, an oven. 
         [0037]    Further, while the distal end of the flow wheel blades have been shown as substantially linear about the width of the blades, it should be pointed out that other embodiments can be used. For example, in one embodiment the distal end of the flexible extension, if a flexible extension is used and/or the blade comprises a curvilinear geometry along the width of the conveyor. The curvilinear geometry can be designed to pierce through the interlocking bed of product. Consequently, in one embodiment, the distal end of the flexible extension and/or the distal end of the blades can comprise curvilinear geometry including but not limited to spike configurations, pointed configurations and variations thereof. 
         [0038]    While this invention has been particularly shown and described with preferred embodiment, it will be understood by those skilled in the art that various changes and form detail may be made therein without departing from the spirit and scope of the invention.