Abstract:
A method for cooking food includes heating a liquid cooking medium in a cooking vessel having a “U”-shaped structure having a height is sufficient, with sufficient medium added, to attain a hydrostatic pressure at a predetermined lower depth that is substantially greater than ambient atmospheric pressure. The food is conveyed through the vessel, mostly cooking at the bottom, where the hydrostatic pressure facilitates a cooking of the food at a rate substantially greater than a rate at ambient pressure. A further aspect of the invention is a method for reducing wastewater output and makeup water usage when cooking a food containing a complex carbohydrate. This method causes released complex carbohydrate to cause a lower viscosity increase than at ambient pressure, thereby increasing a cooking effectiveness of the water and reducing a need for adding makeup water and disposing of wastewater.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims priority to provisional application Ser. No. 60/227,561, “Continuous Cooking Apparatus and Method Employing Hydrostatic Pressure,” filed Aug. 23, 2000. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The present invention relates to the substantially continuous cooking of food products and, in particular, to cooking under hydrostatic pressure of a liquid for improving cooking temperatures and cooking times.  
         BACKGROUND OF THE INVENTION  
         [0003]    Cooking of foods in a heated liquid typically requires the liquid within which the food is being cooked to combine with the food as well as provide a cooking temperature sufficient for completing the cooking process. By way of example, when cooking food products such as pasta, rice, legumes, or vegetables, large amounts of water are absorbed during the cooking process, with the weight of the cooked food generally increasing to 250% of the original dry weight for pasta, for instance. Further, it is known to cook food products within enclosed containers such as cans to provide for cooking under pressure developed within the can. However, the amount of liquid that can be absorbed by the food product is limited to that carried within the can. The cooked food contained within the can and the can are cooled, labeled, packaged, and prepared for delivery to a point of sale. However, while the cooking process may be enhanced by the pressure-style cooking within an enclosed can, it is not practical to remove the cooked food from the can for further preparation such as in a frozen entree. As a result, cooking within a can has typically only been used when no subsequent food preparation process is needed or desired.  
           [0004]    Continuous cooking processes are known in the art. For example, Spiel et al. (U.S. Pat. No. 4,155,293 disclose cooking under atmospheric pressure in hot water to hydrate the food. Hickey (U.S. Pat. No. 3,614,924) teaches a conveyor and discharge chute for conveying a food product through a cooking bath comprising cooking fat. Williams (U.S. Pat. No. 4,582,047) discloses a high-humidity steam cooker including a continuously running conveyor for processing large volumes of food products passed through an energy-efficient steam cooker that preserves the product&#39;s humidity, flavor, and appearance with water temperatures disclosed at essentially atmospheric pressures. Mette (U.S. Pat. No. 4,787,300) teaches an apparatus for continuously cooking and dehydrating foodstuffs, the apparatus including a multizone installation for preheating, boiling, and recooling through which the foodstuffs are passed. Larsen (U.S. Pat. No. 5,493,956) discloses a tank apparatus having movable rollers for receiving a pasta strand and routing the strand around rollers, including floatable rollers, for passing the pasta strand through the water bath to an exit conveyor. Depending on the blanching time required, movable rollers are repositioned to a desired elevation within the tank for blanching or cooking the pasta as it is transported through the water within the tank. D&#39;Alterio et al. (U.S. Pat. No. 4,752,491) disclose the cooking of pasta ribbons on a zigzag conveyor passing through water carried within a tank.  
         SUMMARY OF THE INVENTION  
         [0005]    It is an object of the present invention to provide an apparatus and method for cooking a foodstuff in a fluid cooking medium.  
           [0006]    It is also an object to provide such an apparatus and method for reducing cooking time.  
           [0007]    It is an additional object to provide such an apparatus and method that achieve a substantially continuous cooking process.  
           [0008]    It is a further object to provide such an apparatus that has a smaller footprint than known previously in the art.  
           [0009]    It is another object to provide such an apparatus and method that permit the absorption of cooking medium into the foodstuff.  
           [0010]    An additional object is to provide such an apparatus and method that requires less cooking medium.  
           [0011]    A further object is to provide such an apparatus and method that reduces a production of waste fluid.  
           [0012]    Another object is to provide such an apparatus and method that reduces an amount of added “makeup” cooking fluid and waste fluid.  
           [0013]    It is yet an additional object is to provide such an apparatus and method that assist in reducing potential microbial contamination.  
           [0014]    It is yet a further object to provide such an apparatus and method for improving a quality of the cooked foodstuff.  
           [0015]    It is yet another object to provide an apparatus and method for sterilization.  
           [0016]    These and other objects are achieved by the present invention, one aspect of which is a method for cooking food. The method comprises the steps of heating a liquid cooking medium in a cooking vessel. The vessel has an open top, a bottom, and a wall having a vertical height. The height is sufficient, and there is sufficient medium added, so as to attain a hydrostatic pressure in the cooking medium at a predetermined lower depth that is substantially greater than ambient atmospheric pressure.  
           [0017]    The next step comprises downwardly conveying food to be cooked from an entry area at a surface of the cooking medium to the lower depth. The hydrostatic pressure thus facilitates a cooking of the food at a rate substantially greater than a rate at ambient pressure.  
           [0018]    Another aspect of the present invention is for enhancing a food cooking process using increased hydrostatic pressure. The method comprises the steps of placing a predetermined quantity of food into a container and conveying the container on a pathway having a downward component through a heated cooking medium. The heated cooking medium has a sufficient depth so as to increase hydrostatic pressure along the column to at least about 1.25 atmospheres, that is, 0.25 atmospheres above ambient pressure at sea level. In order to obtain such a pressure level at sea level, for example, a pathway would comprise at least 4-5 feet downward.  
           [0019]    Yet another aspect of the present invention is an apparatus for cooking food that comprises a cooking vessel as above. Means are also provided for heating the cooking medium and for downwardly conveying food to be cooked from an entry area along the predetermined level to the lower depth. As above, this is for permitting the hydrostatic pressure to facilitate cooking the food at a rate substantially greater than a rate at ambient pressure.  
           [0020]    A further aspect of the present invention is a method for reducing wastewater output and makeup water usage by a cooking process for a food comprising a complex carbohydrate. This method comprises the steps of heating water in a cooking vessel as above and downwardly conveying the food to be cooked to the lower depth, also as above. This method further causes released complex carbohydrate from the cooking food to cause a lower viscosity increase than a viscosity increase at ambient pressure, thereby increasing a cooking effectiveness of the water and reducing a need for adding makeup water and disposing of wastewater. In addition, the more rapid cooking times of the present invention also decrease complex carbohydrate leaching from the food being cooked, again increasing cooking effectiveness and reducing a need for adding makeup water and wastewater disposal. 
       
    
    
     BRIEF DESCRIPTION OF DRAWING  
       [0021]    Embodiments of the invention are described, by way of example, with reference to the accompanying drawings in which:  
         [0022]    [0022]FIG. 1 is a partial cross-sectional side elevational view of a first embodiment of the present invention;  
         [0023]    [0023]FIG. 2 is a partial cross-sectional end view of a cooking container portion of FIG. 1;  
         [0024]    [0024]FIG. 3 is a partial top view of FIG. 1;  
         [0025]    [0025]FIGS. 4A and 4B are partial side and end views of a food basket of FIG. 1;  
         [0026]    [0026]FIG. 5 is a partial cross-sectional elevation view of a second embodiment of the present invention;  
         [0027]    [0027]FIG. 6 is a partial cross-sectional elevation view of an alternate conveyor mechanism of the present invention for transferring cooked product to a cooling section;  
         [0028]    [0028]FIG. 7 is a partial cross-sectional elevation view of a third embodiment of the present invention; and  
         [0029]    [0029]FIG. 8 is a partial cross-sectional side elevational view of a fourth embodiment of the present invention.  
         [0030]    [0030]FIG. 9 is a cross-sectional side elevational view of a fifth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]    The present invention will now be described more fully with reference to FIGS.  1 - 9 . This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to convey a scope of the invention to those skilled in the art.  
         [0032]    As illustrated with reference to FIGS.  1 - 4 B, one embodiment  10  of the apparatus of the present invention includes a cooking vessel  11  having a generally “U”-shaped cross section for holding a column of cooking medium, such as, but not intended to be limited to, water  12 . The cooking vessel  11  has two separate vertical columns  13 , 14 , each of which extends upwardly from and is in fluid communication with a common bottom leg  15 . The vessel  11  has a length  150 , a width  16 , and a vertical height  17 . Each column  13 , 14  also has an open top  18 , 19  and a substantially rectangular enclosing wall  20  (FIGS. 2 and 3). The height  17  is sufficient for holding the cooking liquid, such as water,  12  to a predetermined level  21  for attaining a hydrostatic pressure in the water  12  at a predetermined lower depth  22  in the vessel  11 . As stated above, the hydrostatic pressure is substantially greater than ambient atmospheric pressure, and is typically in a range of 1.25-2.0 atmospheres, that is, 0.25-1 atmosphere above the ambient pressure at sea level. The vertical height  17 , which in a preferred embodiment would comprise a range of approximately 8-30 feet at sea level, provides increased pressure with increasing water depth and thus an increased temperature at the bottom portion of the vessel  11  is possible resulting from the columns  13 , 14  of water  12  above the bottom leg  15 .  
         [0033]    An entry area  23  is along a top sector  24  of the first vertical column  13 , and an exit area  25  is along a top sector  26  of the second vertical column  14 . The entry  23  and exit  25  areas are for the entry and exit of a conveyor for downwardly and upwardly conveying the food to be cooked to and from the lower depth  22 . The conveyor comprises in a preferred embodiment a pair of parallel sprocket chains  27  engageable at each of four corners by sprockets  28 - 31 , one of which  28  comprises the drive sprocket. The chains  27  form a continuous loop through the first column  13 , the bottom leg  15 , the second column  14 , and across the space between the columns  13 , 14 .  
         [0034]    A plurality of containers  32  (FIGS. 4A and 4B) are affixed for free rotation in spaced relation from each other via a pivot  33  on each side attachable to the chains  27 . Each container  32  is adapted to hold a discrete quantity of the food  34  to be cooked therein. Each container  32  comprises a perforated metal basket in a preferred embodiment. The pivotability about pivot  33  permits that, when the chains  27  rotate about the closed loop, the containers  32  always remain substantially upright unless affected by a force in another direction, not unlike a Ferris wheel.  
         [0035]    As shown in FIG. 1, food to be cooked  34 , such as, for example, pasta for blanching, is delivered to the apparatus  10  via a conveyor belt  35  that terminates at a location  36  above the conveyor. As a container  32  goes by the conveyor belt  35  at discrete intervals, a mechanism such as is known in the art is provided for coordinating an activation of the belt  35  when a container  32  is beneath the belt  35 , with gravity permitting the food  34  to drop from the belt  35  into a container  32 . The speed of sprocket rotation is preferably variable, for adjusting cooking time depending upon such factors as type of food to be cooked, cooking medium, and ambient altitude.  
         [0036]    The water  12  is heated with a steam injector in fluid communication with an interior  37  of the vessel  11  along the vessel bottom leg  15 . The steam injector in this embodiment comprises a steam inlet  38  and a steam manifold  39  having a plurality of steam nozzles  40 . The steam manifold  39  is in fluid communication with the steam inlet  38 . This is not intended as a limitation, as other heating methods may well be envisioned by one of skill in the art, such as, but not intended to be limited to, electrical resistance-type heat production (see, for example, FIG. 7). It will also be obvious to one of skill in the art that the heating means need not necessarily be at the bottom leg  15 , and that they may be positioned anywhere along the water column, although at or adjacent the bottom leg  15  is believed to represent a preferred embodiment.  
         [0037]    Means are also provided for cooling the cooked food  34 ′ and for transferring food  34 ′ from the containers  32  to the cooling system. As shown in FIGS. 4A and 4B, each container  32  also has on each side a second pivot  41 . As the container emerges from the exit area  25  and rounds the corner at sprocket  28 , the second pivot  41  is engaged by a lifting arm  42 , which tilts the container  32  to empty the cooked food  34 ′ into a chute  43 , which in turn leads via a serpentine pathway  44  to a cooling water bath  45 . Another conveyor belt  46  takes the cooled food  34 ″ out of the bath  45  and drops it onto an outbound conveyor  47 , which leads, for example, to a packaging area.  
         [0038]    It may also be desired to pretreat the food  34  to be cooked with steam prior to entry into the vessel  11 , which is represented in FIG. 1 by nozzle  48 .  
         [0039]    One feature of the present invention includes cooking of the food within free water as opposed to within closed containers such as the cans earlier described. For the present invention, cooking includes not only heating the food, but allowing it to absorb the free liquid to combine with the food being cooked and complete the cooking process as desired. As described, products such as pasta absorb large amounts of water during cooking, and typically such foods as pasta can increase in weight by approximately 250%.  
         [0040]    As illustrated with reference to FIGS.  5 - 8 , alternate embodiments  10 ′,  10 ″,  10 ′″,  10 ″″ of the apparatus described are presented with reference to FIGS.  1 - 4 B, wherein like elements are indicated by the same reference numeral with the commensurate number of primes.  
         [0041]    A second embodiment  10 ′ (FIG. 5) includes an arcuate-shaped bottom section  15 ′ for the vessel  11 ′ with the cooling bath  45 ′ delivering cooked food product  34 ′ that has settled to the bottom of the cooling bath  45 ′ to a water lock for discharging onto the discharge conveyor  47 ′.  
         [0042]    In the embodiments of FIGS. 5 and 6, the food  34 , 34 ′ is carried on substantially flat carriers  32 ′, 32 ″ that are carried by a chain  27 ′, 27 ″ and disgorge the cooked food  34 ′ when the carrier  32 ′, 32 ″ is tilted upon proceeding toward the top of a unitary sprocket  28 ′ in the case of FIG. 5 and a first of a pair of sprockets  28 ″, 29 ″ in the case of FIG. 6.  
         [0043]    Yet a further embodiment includes the cooling bath  45 ′, 45 ″, 45 ′″ carried at various locations (FIGS. 5 and 6) or integrally formed (FIG. 7) within a housing that includes the vessel  11 ′″ and the cooling bath  45 ′″. In the embodiment  45 ′″ of FIG. 7, three pairs of sprockets  28 ′″- 30 ′″ are required to maintain a level attitude of the carriers  32 ′″ through the water bath  45 ′″ after exiting the second column  14 ′″.  
         [0044]    In an additional embodiment  10 ″″ (FIG. 8), the vessel comprises a unitary, substantially rectangular cooking vessel  11 ″″, the chains  27 ″″ and containers  32 ″″ traveling along the sides  13 ″″, 14 ″″ and bottom  15 ″″ for cooking, and disgorged in like manner to the first embodiment  10 , the movement of the output conveyor  47 ″″ in this case perpendicular to the plane of the drawing.  
         [0045]    A fifth embodiment  10   (5)  (FIG. 9) comprises a substantially rectangular cooking vessel  11   (5)  comprising a unitary tower. A flexible carrying member such as a wire or chain  27   (5)  carrying at least one container  32   (5)  is affixed to a vertical transport means, which may comprise, for example, a mechanism such as a mechanical crank  30   (5) , not unlike a well and bucket arrangement, for lowering and raising the container  32   (5)  to and from a cooking level adjacent the bottom  15   (5)  of the vessel  11   (5) . In this embodiment  10   (5)  the food to be cooked would be placed into the container  32   (5) , lowered to the vessel bottom  15   (5) , where it would remain for a time sufficient to achieve a desired cooking level, and then raised (shown as a dotted container  32   (5) ) to the vessel top  18   (5) , where the cooked food  34 ′ may then be post-treated as desired.  
         [0046]    The apparatus herein described with reference to the attached drawings are directed for use in blanching and cooking foods such as pasta, rice, beans, meat, and vegetables in a cooking fluid, such as water or oil, and cooking and cooling such foods within cooling baths if desired. However, it will be appreciated by one skilled in the art that the hydrostatic cooking herein described by way of example for the present invention may include cooking other foods within other liquids or other mixtures without departing from the intent and teachings of the invention.  
         [0047]    In operation, and by way of example with reference to cooking of pasta, with an approximately 15-foot-high container, there is approximately one-half an atmosphere increase in pressure that can be used to achieve cooking temperatures of 224° F., 12° F. above the normal boiling point of water. With such, pasta will cook in 30% less time. Depending on the shapes of the pasta, the reduction in cooking time will be from 10 to 7 minutes with no breakage of the pasta due to handling and minimal starch loss in the cooking water. If the container is increased in height to approximately 30 feet, the pressure increase is close to one atmosphere and results in temperatures of approximately 240° F. With such an increase in temperature, the cooking time for the pasta is reduced by 50% of the normal cooking time while including similar benefits. The apparatus of the present invention may additionally be used for noncooking applications such as a continuous autoclave for sterilization of items such as medical implements or for pasteurization of food that does not require cooking.  
         [0048]    The present invention permits food products to be cooked at temperatures higher than normal boiling point temperatures (212° F.) by cooking under hydrostatic pressure higher than atmospheric pressure typically used for the continuous cooking and conveying of pasta. The food cooks faster, is more efficiently cooked, and in certain cases retains and/or enhances desirable properties of the food products that can be degraded by longer cooking times.  
         [0049]    The present invention permits continuous cooking of food products in large quantities of free liquid such that the food is in direct contact with a cooking fluid bath rather than being enclosed in a vessel for pressure cooking, such as a can. Further, water can be added as desired/needed during the cooking process. The hydrostatic column of water generates sufficient pressure increases to enhance the cooking process while permitting the continuous processing of the food from an input side to an exit side which are at atmospheric pressure. No pressure locks or pressure vessels, as defined by ASTME Codes, are required.  
         [0050]    As earlier described with reference to the attached drawings, the apparatus of the present invention conveys food through the cooking fluid in containers made of perforated metal or other porous material. Preferably the material in contact with cooking fluid comprises food-quality stainless steel, although this is not intended as a limitation. This provides gentle treatment of the food, which prevents damage to delicate food products. A conveying mechanism for the basket may be a bucket elevator mechanism, by way of example. The bucket may be enclosed, if desired, to prevent food from escaping, which top can be opened during the loading and unloading of the food product from the cooking cycle. The “U”-shaped design, herein described for a preferred embodiment, occupies a very small amount of floor space (footprint), which is desirable in a food plant that typically has available vertical space, but limited floor space. Again, as herein described, a cooling section can be placed within the “U”-shaped space.  
         [0051]    Because of the decreased cooking time and higher temperatures achieved, a reduction in the starch leaching into the cooking water can be achieved, and the starch that does escape from the food is less viscous in the cooking water, making the cooking process more efficient. Suspended starches cause loss in weight and throughput of food product and cause significant cost for wastewater treatment of the processing water. Because of the “U”-shaped design herein described, the amount of water used for processing and cleaning is significantly reduced in comparison to conventional cookers and blanchers, which use vat-styled containers. The efficient cooking process, as well as the efficient use of floor space, are desirable features made available by embodiments of the present invention, and are believed to confer significant environmental benefit. Further, the increased pressure and temperature experienced by the food assist in a reduction of microbial contamination, thereby improving sanitization and sterilization of the food. Pretreatment with steam is also believed to confer a toughening of the product, so that an effect of starch in the cooking water is not as deleterious, nor is as much starch released by the cooking food. In addition, the increased pressure conferred by the present invention is useful in “locking in” beneficial food characteristics such as nutrients and flavor.  
         [0052]    Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing description and drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed.