Patent Publication Number: US-6220150-B1

Title: Apparatus for producing a reconstitutable dehydrated food product

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention is in the field of food products and, more particularly, directed to an apparatus for producing a dehydrated food product that is easily and quickly reconstitutable, and that, upon reconstitution, has a textured composition closely resembling the consistency and texture of conventionally-prepared refried beans. 
     2. Art Background 
     The prevalence of fast-food style establishments in recent years has been accompanied by an increased demand for reconstitutable food products, such as, for example, dehydrated refried beans. From an economic point of view, such products have several advantages. For example, each establishment can buy and store the product in bulk quantities without the risk of spoilage. Also, since the product is normally reconstituted in a matter of minutes by adding only water, there are savings in time, energy, and labor associated with the use of these products. Finally, since there is no need to continually prepare the food product in the conventional manner (i.e., to make the food fresh, and on a daily basis), there is also no need for each establishment to keep extra equipment (e.g., cookware, etc.) on the premises. As such, methods have been devised to produce reconstitutable food products that, ideally, could be prepared very quickly, and would have the taste, texture, and appearance of their conventionallyprepared counterparts. 
     Current methods and apparatus for producing such food products and, more specifically, refried bean products, required that one consider various factors. For example, to satisfy the requirement that the raw beans be mixed as they are hydrated and, also, as they are cooked, a number of the methods presently known employ rotating vessels. Vessels that rotate are used so that the beans can be contacted with a small amount of water that is diminishing as the water is absorbed by the beans. Controlled amounts of water are used during the cooking process in hopes that at the end, little or no water remains—only the cooked, hydrated beans. This is difficult to achieve, and the art has searched for various methods, as excess water can result in yield loss (some of the beans will dissolve into the water) and/or a pasty product that is difficult to further process and dry. Merely placing the beans in water has other shortcomings. For example, such method can result in some beans becoming too soft, while others do not become properly hydrated. Further, prior art vessels are generally quite bulky, which not only translates into added and more-frequent maintenance requirements, but also makes it more difficult to achieve economies of scale. Further still, generally, in many prior art vessels only a small amount of beans can be treated. In other words, to achieve the benefit of a small water-to-bean ratio, rotating vessels of particular configurations and having limited capacities were used. Even then, it is difficult to control the water absorption into the beans. 
     Yet other shortcomings relate to the starting materials that are used. In a typical prior art process for preparing refried beans, dry, raw beans are placed into the vessel, and a small quantity of water is added. Unless the vessel rotated, the beans on the top of the pile could absorb a different amount of water as compared to the beans at a position lower down. Further, as the water level in the vessel decreases, yet further non-uniform water absorption throughout the beans could result. It is known that raw beans typically have an initial moisture content in the range 6%-14%. However, current methods have difficulty using a batch of raw material that spans this entire range because the disparity in initial moisture levels exacerbates the variations in water absorption during hydration with small amount of water, which would, in turn, result in a non-uniform final product. As such, in order to use many prior art methods and apparatuses, the practitioner is limited to using rotating vessels and to batches of raw materials, each of which falls within a small sub-group of initial moisture-content ranges (e.g., those in the 6-8% range, or those in the 10-12% range, etc.). 
     In the current state of the art, there are also disadvantages associated with the end product itself (e.g., with the dehydrated bean product). For example, even though one goal of dehydrated food products is to allow for rapid water take-up at reconstitution, this goal is only partially met in current dehydrated bean products. As is known in the art, most current methods produce products that are either in the shape of small pellets or in the shape of flakes or in the shape of fine powder. In the case of pellets, because of the way in which the final product is prepared, typically only a small portion of the surface area of each pellet (i.e., typically, the two ends of each pellet) provides areas through which water can easily be absorbed; the remainder of the pellet&#39;s outer surface is inefficient in absorbing water. Flakes, on the other hand, due to their method of manufacture, have a harder outer surface and are generally treated with oil on their surface, which is a water repellent, so that water take-up upon reconstitution is actually slower than it may be otherwise. Therefore, in both cases, water absorption rates are not optimal. 
     Moreover, upon reconstitution, many of the dehydrated products currently available turn into paste-like, or other similar, uniform compositions, where there is generally a lack of texture in the food. This is especially true with methods and apparatuses that produce a granular, rather than a pelletized, or flake-like, dehydrated product. In addition, regardless of the actual shape and form of the final product, there is no simple provision in existing methods and apparatuses for varying (i.e., custom making) the texture of the final product as desired. 
     Reference is made to U.S. Pat. Nos. 4,676,990; 4,735,816 and 4,871,567 as further examples of the prior art. These references illustrate various bean-making processes, but all have a number of shortcomings. For example, in the &#39;990 patent, a pelletized product is produced by particularized processing steps and related apparatus. In the &#39;816 and &#39;567 patents, a thin, flake-like product is produced by means of yet other particularized processing steps and apparatus. These processes are complicated and the final products are only marginally close to refried beans made to have a pleasant texture with a desired amount of bean particulates. 
     The features and advantages of the present invention will become more apparent through the following description. It should be understood, however, that the detailed description and specific examples, while indicating particular embodiments of the invention, are given by way of illustration only and various modifications may naturally be performed without deviating from the spirit of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an illustration of a vessel and rotating member of an embodiment of the invention. 
     FIG. 2 shows a cross-sectional view of the vessel and rotating member of FIG. 1, taken along line II—II. 
     FIG. 3 shows an illustration of a shaft and rotating member of an embodiment of the vessel. 
     FIG. 4 shows an illustration of a channel and forming conduit of an embodiment of the invention. 
     FIG. 5 shows a cross-sectional view of the channel and forming conduit of FIG. 4, taken along line V—V. 
     FIG. 6 shows a condensed flow-chart format of non-exhaustive, alternative embodiments of a method which may be practiced by use of an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     An embodiment of the present invention is related to an apparatus for producing a reconstitutable dehydrated food product, comprising a stationary hydration/cooking vessel, a chopping system, and a forming mechanism. The hydration/cooking vessel is equipped with a perforated internal baffle which rotates continuously to ensure contacting of all beans or other foods with a small and continuous diminishing quantity of water; the baffle holes ensure that fluids within the vessel are exchanged freely between the two chambers of the vessel as defined by the baffle. Once cooked, the beans are transferred to the chopping system, wherein they are urged through a channel, comprising a rotating blade that chops, and a perforated plate that re-sizes, the beans into a texturized composition. The blade speed and the size of the holes in the perforated plate can be changed in order to achieve different textures within the composition. The latter is then treated in a forming mechanism, comprising a shaped conduit, wherein the composition is formed into a flat sheet, which is then treated so as to produce an improved reconstitutable dehydrated bean product. 
     The stationary hydration/cooling vessel of the present invention has significant processing advantages. First, since the vessel is stationary, it is relatively simple to construct large units which result in substantial economies of scale. Second, by using a horizontal cooking vessel with a perforated internal baffle having a length and width that are substantially the same as the vessel, it is easy to assure that, during processing, all of the beans are gently and continuously contacted with a small, and diminishing quantity of liquid. 
     Embodiments of the present invention are directed to an apparatus which may be used to practice a method of preparing a reconstitutable, dehydrated food product by means of hydrating and cooking raw beans, so that all of the cooked beans achieve a similar moisture content, chopping the cooked beans into a flat sheet of texturized composition, partially drying the sheet, breaking the sheet up into large chunks, and then completely drying the chunks. 
     The above-described process, particularly the sequence involving the latter three steps, results in a bean product that absorbs water faster and more uniformly upon reconstitution. Also, after the raw beans have been hydrated, the excess liquid can be removed from the vessel, thus eliminating some flatulent sugars from, and improving the digestibility of, the final bean product. Moreover, salt and other flavoring may be added to a portion of the removed excess water and then added back to the vessel before the beans are cooked. Alternatively, flavoring may be added during the chopping, or other steps, of the above-described process. Finally, depending on the desired texture and chunkiness of the final product, a portion of the cooked whole beans may be removed before the chopping step, and then added to the beans in a subsequent step, or to the final product upon reconstitution. 
     FIGS. 1 and 4 show one embodiment of the apparati of the present invention. As shown in these figures, a stationary vessel  10  comprises a vessel shell  12 , and a central shaft  30 . Although the figures show that the vessel  10  has a substantially circular cross-section, this is done for purposes of demonstration only, and it is intended that the invention encompass other vessel configurations as well. 
     The vessel  10  is also equipped with a solid-blade baffle  20 , which is attached to, and rotates around, shaft  30 . In the preferred embodiment, baffle  20  has a length and width that are substantially as long as the length and width, respectively, of the vessel  10 . Therefore, in the embodiment of FIGS. 1 and 2, the width of the baffle  20  is substantially commensurate with the diameter of a cross-section of the vessel  10 . To ensure proper operation, a clearance of about {fraction (1/16)} inch is maintained between the inner surface  18  of the shell  12  and an edge  24  of the baffle  20 , as well as between an end  28  of the baffle  20  and an end  11  of the vessel  10 . 
     As is shown in FIG. 2, at any point in time, the baffle  20  divides the inner space of the vessel  10  into two chambers,  14  and  16 , where each chamber is defined substantially by the space between the inner surface  18  of the vessel shell  12 , and a wall  26  of the baffle  20 . The solid-blade baffle  20  has transverse holes  22  (shown in FIG. 1, and by dashed lines in FIG. 2) which, while large enough to allow fluids within the vessel  10  to travel between the chambers  14  and  16 , are small enough to keep the vessel contents  100  separated on each side of the baffle  20 . 
     In the preferred embodiment, the vessel  10  is employed both to hydrate raw beans and to cook the hydrated beans. As will be explained in detail below, when used in the latter capacity, the vessel  10  is transformed into a pressure cooker, using steam to cook the beans. To achieve uniform steam injection into the chambers  14  and  16 , steam is forced through the shaft  30 , and enters each chamber  14 ,  16  through steam outlets  32  which are arranged along the length of the shaft  30  (FIG.  3 ). However, steam can also be injected into the vessel through other suitably placed entrances to the vessel. 
     FIG. 4 depicts the remaining components of an embodiment of the invention. Channel  40  is an elongated hollow structure which is equipped with a rotating blade  50  and a perforated plate  60  adjacent its distal end  42 . The proximal end  41  of the channel is located adjacent the vessel  10  and receives the cooked beans from the vessel  10 . Once received, the beans are urged through the channel by a piston or other suitable mechanism, such as a rotating shaft with advancing flights. Therefore, as the blade  50  rotates, it chops cooked beans into pieces, which are then urged through the holes  62  of perforated plate  60  (FIG.  5 ). It is noted that, although the plate  60  is shown to have a rectangular cross-section, the present invention is not intended to be limited to this configuration; rather, both the plate  60  and the channel  40  may have cross-sections of various geometries. Moreover, the rotating blade  50  and perforated plate  60  may be disposed at other locations along the longitudinal axis of the channel  40 . 
     The channel  40  is adjacent to, and in flow communication with, a forming conduit  70 , which comprises an inlet  72  and an outlet  74 . As is explained in more detail below, chopped beans exit the outlet  74  in a flat sheet of textured composition, where the flat sheet has a generally rectangular cross-section, and the thickness of the sheet is determined by the thickness T of the conduit outlet  74 . In a preferred embodiment, T typically lies in the range ⅛-¼ inch. 
     FIG. 6 shows, in condensed flow-chart format, two non-exhaustive, alternative embodiments of the method of the present invention. In practice, raw whole beans are placed into chambers  14  and  16  of stationary vessel  10 , on either side of the baffle  20 . Water is then added to the vessel  10  in an amount that is at least equal in weight to the weight of the beans in the vessel. Although, in principle, the beans could be hydrated by just allowing them to soak in the water for a period of time, experience has shown that this practice results in non-uniform water absorption by the beans. That is, over time, as the beans on the top of the pile absorb water, the water level in the vessel decreases, which causes non-uniform water absorption throughout the pile of beans. 
     On the other hand, it is known that raw beans typically have an initial moisture content in the range 6%-14%. However, given their non-uniform hydration procedures, prior-art methods cannot use a batch of raw materials that includes beans and legumes from this entire range because the disparity in initial moisture levels may exacerbate the variations in water absorption during hydration, so that the result would be a highly non-uniform final product. As such, for every batch of raw materials, the prior art is limited to using raw beans that fall within a small range of initial moisture content, e.g., 6-8%, or 12-14%. The present invention, however, is not so limited. 
     In the preferred embodiment, once water has been added to the raw beans in the vessel  10 , the baffle  20  is activated, and the beans are hydrated at atmospheric pressure and a temperature between 150° F. and 185° F. By rotating around the central shaft  30 , the baffle  20  continuously brings the beans into contact with water, so that the beans do not generally remain in one place throughout the hydration step. That is, the beans are continuously replaced from the top to the bottom, and vice versa. In addition, the holes  22  of the baffle  20  ensure that water is exchanged between the chambers  14  and  16 , so that the hydrating water is not stationary either, and reaches the beans in both chambers. The combination of the rotating baffle  20  and the water exchange between the chambers  14  and  16  allows the moisture level in all of the beans to equilibrate to about the same level. Typically, during the hydration step, the beans absorb between 50% and 80% of the water that they are capable of absorbing. 
     In the preferred embodiment, the legumes are cooked using direct steam injection. Therefore, there is no need to have any water in the vessel  10  while the beans are being cooked. Thus, once the beans have been properly hydrated, any excess water can be removed from the vessel  10 . There is, however, an added advantage to removing excess water, namely, that flatulent sugars are also removed along with the excess water, which results in improved digestibility of the final bean product. 
     An option, at this point, is to add salt or other flavoring or oil to a portion of the removed water, and then return the combination to the vessel  10 . In cases where this is done, a relatively small amount of water is added back to the vessel  10 , so that it is generally insufficient to cover all of the beans in both chambers  14 ,  16 . Also, either as a substitute for, or a supplement to, this option, salt and other flavoring may be added at various other steps within the process (e.g., during the chopping step). 
     Using direct steam injection, the vessel  10  is now pressurized above atmospheric pressure, and the beans are cooked at a temperature greater than 212° F. Specifically, steam is forced through the central shaft  30  and is injected into the vessel  10  and chambers  14  and  16  through the steam outlets  32 . During the cooking step, the baffle  20  rotates around the central shaft  30  as it did during the hydration step, thus continuously contacting beans in each chamber  14 ,  16  with the small amount of water that rests at the bottom of the stationary cooling vessel. At the end of the cooking step, there is little or no water left in the vessel, and the beans are removed and transferred to the channel  40 . 
     Within channel  40 , the cooked beans are urged towards the distal end  42  via the piston/rotating shaft. As the beans are urged forward, they are chopped by a rotating blade  50 , which rotates at an angular velocity ω. The beans are then pushed through the holes  62  of the perforated plate  60 , which is located distal to the rotating blade  50  and resizes the chopped beans as they travel past the plate. In this way, a texturized composition is created, wherein the texture, or chunkiness, of the composition (and of the final bean product) is determined by the angular velocity ω of the blade  50  and the hole sizes of the plate  60 . Therefore, the present invention offers the capability of varying the texture of the final bean product to a desired consistency by changing the blade angular velocity ω, the size of the plate holes  62 , or both. 
     The chopped beans are next fed through the forming conduit  70 . As shown in FIG. 4, in the preferred embodiment, the inlet  72  of the forming conduit  70  is connected to the distal end  42  of the channel  40 . However, this is not required, as long as the conduit  70  and the channel  40  are in flow communication, so that chopped beans exiting the channel from its distal end  42  flow into the forming conduit through its inlet  72 . For example, the inlet  72  may comprise a hopper, or other inlet configuration, that is situated within close proximity of, but not necessarily connected to, the channel  40 . Regardless, once the chopped beans are in the conduit  70 , they are urged towards the conduit outlet  74 . The outlet  74  has a rectangular cross-section, with a thickness T, and a width that is considerably larger than T. Therefore, as the texturized composition exits the conduit outlet  74 , it is formed into a substantially flat generally continuous elongated sheet, with a rectangular cross-section of thickness T. Typically, T lies within the range of approximately ⅛-¼ inch. 
     The flat elongated sheet of texturized composition is next dried from top to bottom, but only partially. It has been found that, by partially drying first, and then breaking up the texturized composition of beans into pieces, chunks of bean product are produced that have rough uneven, porous, thick and undulating edges. Moreover, each chunk has a larger surface area containing these rough edges than do bean products prepared according to prior-art methods. This translates into pieces with a porous surface that takes up and absorbs water much more easily and quickly upon rehydration. That is, this improvement allows for higher absorption rates, as well as a more uniform pattern of water take-up than is available in the prior art. 
     The partial drying of the sheet of texturized composition is achieved by using conventional drying methods and apparatuses. Once partially dried the sheet is broken up, or formed, into chunks where each chunk is approximately 0.75 to 1.5 inches in size. These chunks are then further dried down to a final moisture content of about 10%, thus producing a shelf stable bean product of a desired texture, with improved water absorption qualities and enhanced digestibility. Alternatively, the bean sheet can be first completely dried and then broken into smaller pieces. 
     As shown by the dashed arrows in FIG. 6, an alternative embodiment of the method disclosed herein may include the following steps: After the beans are cooked in the vessel  10 , they are divided into a first unchopped portion and a second unchopped portion. The first portion is then taken through the remainder of the process as before, while the second portion is kept separate. That is, the beans in the first portion are chopped in the channel  40 , and then formed into a sheet of texturized composition in the forming conduit  70 . However, before the sheet is partially dried, the beans from the second portion, which have remained unchopped, are added to the sheet. The entire sheet is then partially dried, broken up into chunks and, dried further. This procedure allows an added measure of control over the texture and composition of the final bean product. 
     An example is set forth below to further illustrate the present invention: 
     EXAMPLE 
     12 liters of hot water were placed in a small (8 inch diameter by 24 inch long) horizontal cylindrical cooking vessel. The water was then further heated to 185° F. by passing steam through the shaft of the central baffle, while slowly rotating the baffle so as to agitate the water. 
     Approximately 4000 ml of the hot water was drained from the vessel, and 7 lb. of dry pinto beans were then placed in the vessel—one half of these beans being distributed along one side of the baffle, and the remaining half on the other side of the baffle. 
     The vessel was then maintained at atmospheric pressure, and the baffle was alternately and continuously slowly rotated for one (1) minute each in the clockwise and counterclockwise directions. Steam was added through the baffle shaft to maintain the bean/water mixture temperature between approximately 180° F. and 190° F. The beans immediately started to absorb the hot water, and the rotating baffle served to mix and contact the beans with a continuously diminishing quantity of water. This hydration step was continued for 20 minutes, after which approximately 6700 ml of broth was drained from the now partially-hydrated beans. 75 grams of salt was then dissolved in 600 ml of the drained broth and this salt solution was returned to the cooking vessel. 
     The hatch to the cooking vessel was now secured and the vessel pressurized with steam and held at a pressure of 10 psig for 40 minutes in order to cook the beans. During this cooking period, the cooking vessel baffle continued to rotate alternatively and slowly for one (1) minute each in the clockwise and counterclockwise directions. In this manner, all the beans were contacted with the remaining and continuously reducing broth volume. 
     At the end of the cooking step, the vessel was depressurized and the cooked beans with very little remaining liquid broth were discharged into a holding vessel. 
     These cooked beans were then chopped and texturized by a small electrically driven meat grinder, which had a front plate with ¼ inch holes and knife cutters which rotated against the inner side of the front plate. 
     The cooked beans were manually fed into the grinder and the textured bean mass collected as it exited through the grinder front plate. 
     The textured bean mass was then placed in a cylindrical vessel, and was shaped into a sheet approximately ⅛ inch in thickness and 4 inches wide by applying pressure to the vessel so as to force the bean mass through a ⅛ inch by 4 inch slot situated at the base of the vessel. 
     As the textured bean mass exited the slot, it was continuously deposited on 6-inch by 6-inch perforated metal squares. 
     These perforated metal squares, supporting the wet bean sheet, were transferred and placed on a conveyor that passes through a convective dryer. 
     The bean sheet was initially dried for  3  minutes and 45 seconds using 400° F. hot air impinging on the top and bottom of the bean sheet. 
     The partially-dried beans were then broken into smaller pieces, placed on the perforated metal supporting squares, and finally dried for 4 minutes in the same convective dryer using 350° F. hot air. 
     After cooling, these dried, textured beans were stored for rapid reconstitution with water, and subsequent use in food items. 
     It will be apparent to a person of ordinary skill in the art that embodiments of the present invention are not limited in their design or application to specific embodiments disclosed herein. For example, injection of steam into the stationary pressure vessel may be accomplished through ports in the vessel walls. Alternatively, recirculating water, rather than directly-injected steam, may be used to cook the beans. 
     Further still, while the process steps and apparatus lend themselves to dried legumes, other food-stuffs are also within the scope of this invention. For example, the apparatus can be used to cook foods such as carrots, celery, meats, chicken, fish and the like without the use of excess amounts of water. Thus, the present invention is intended to encompass all of the embodiments disclosed and suggested herein as defined by the claims appended hereto and any equivalents thereof.