Abstract:
An improved method for preparing a frozen food product is provided. The food product comprises a variety of food pieces that have been precooked in the presence of water and subjected to a process in which substantially all of the free water present with the food pieces is removed. The food pieces are then passed through a continuous freezing unit which increases the rigidity of the food pieces and leaves an amount of water on the surfaces of the food pieces. The food pieces are placed into a heat sealable container that includes a porous end piece along with measured amounts of a freezing gas and an adjuvant. The container is then sealed across the porous end piece and placed on a tumbling mechanism that coats the food pieces with the adjuvant and completes the freezing process as the freezing gas escapes through the porous end piece on the container. After completion of the tumbling process, the containers are resealed beneath the porous end piece so that the porous end piece may be trimmed from the container, allowing the container to be packaged and shipped for sale.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the preparation of a frozen food product for later use, and is based on an improvement over the concepts disclosed in U.S. Pat. No. 4,478,861 issued Oct. 23, 1984, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     In U.S. Pat. No. 4,478,861, there is disclosed a method for preparing a frozen food product. The food product used in the method includes food pieces (such as meat, potatoes, carrots, peas, or the like) that are cooked in the presence of water. After cooking, substantially all of the free water present with the cooked food pieces is removed in a manner known in the art, leaving voids in the food mass formed by the cooked food pieces. The cooked food pieces are then charged to an agitator, which is normally a large rotating drum. While the food pieces are being agitated, a freezing gas, such as carbon dioxide (CO 2 ) gas, is introduced into the agitator to partially freeze the food pieces. The food pieces are only partially frozen by the gas, in order to leave an amount of unfrozen moisture on the exterior surfaces of the food pieces. 
     The reason for leaving the unfrozen moisture on the exterior surfaces of the food pieces is to allow a seasoning, or adjuvant, which is introduced into the agitator after or in conjunction with the freezing gas, to adhere to and coat each food piece. Adding the adjuvant to the partially frozen food pieces insures that the adjuvant will adhere to the residual moisture present on the food pieces. Once the adjuvant is added, additional freezing gas is introduced into the agitator to fully freeze the food pieces. The completely frozen food pieces are then placed within a container for deep freeze storage. 
     However, in the above-identified patent, the method is only capable of manufacturing and packaging a frozen food product in bulk form. In order to place the product into a more commercially viable form that can be sold directly to the ultimate consumer, the product must be repackaged from the original container into a number of smaller packages having a size more useful to the ultimate consumer. 
     Furthermore, when preparing a food product in bulk form, it is difficult to insure that the adjuvant added to the product is evenly distributed throughout the entire product. In many instances, the adjuvant tends to concentrate in certain areas of the agitator, resulting in over-seasoned product in those areas and under-seasoned product in others. 
     Lastly, when preparing a frozen food product according to this method, it is necessary to have a large agitator in which to place the entire batch of food product for preparation. Having an agitator of this size necessarily increases the cost of producing the product by requiring a large expense in acquiring the equipment and for the maintenance and repair of the agitator should it become damaged. 
     Therefore, it is desirable to develop a process by which a frozen food product may be prepared and packaged in containers having a size appropriate for sale directly to an ultimate consumer. 
     Furthermore, it is also desirable to develop a process for preparing a frozen food product in which the adjuvant can be more precisely proportioned with the food product to lessen the occurrence of under-seasoned and over-portions of the food product. 
     Finally, it is desirable to develop a process having the above mentioned advantages that does not require the presence of a large agitator in order to produce the frozen food product. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved method for preparing a frozen food product which enables the frozen food product to be prepared and packaged in a container of a size that can be sold directly to an ultimate consumer. 
     It is a further object of the present invention to provide an improved method for preparing a frozen food product that allows increased precision with regard to the amount of adjuvant added to a predetermined amount of the frozen food pieces. 
     It is a still further object of the invention to provide an improved method for preparing a frozen food product that eliminates the need for a large cylindrical agitator to freeze and mix the adjuvant throughout the food pieces. 
     The present invention is an improved method for the preparation of a frozen food product. In accordance with the various objects of the invention, a number of food particles are cooked in water to a fully prepared state. After cooking, substantially all the free water present with the cooked food pieces is removed in a conventional manner. The removal of the water also does not dry out the food pieces, but leaves the food pieces moist. 
     After the free water has been removed, the food pieces are passed through a continuous freezing unit that partially freezes the food pieces. This initial freezing step does not completely freeze the food pieces, but leaves an amount of unfrozen moisture on the exterior surfaces of the food pieces. 
     Once the initial freezing step is completed, the pieces are weighed and a preselected weight of the partially frozen food pieces is placed into each of a plurality of sealable storage containers. Each container includes porous end sections that form the mouth of the container. In this manner, the food pieces are generally equally distributed amongst the containers. An amount of a freezing gas is also introduced into each container after the food pieces to complete the freezing of the food pieces within the container. The freezing gas used is normally in solid form, so that when the gas sublimates from the solid to the gaseous form, the gas also inflates the container as it freezes the food pieces. 
     After the freezing gas is placed within the container, but before the food pieces are completely frozen, a premeasured amount of an adjuvant is also added to the container. The amount of adjuvant added corresponds to the weight of the food pieces already within the container. The porous end section of the container is then sealed such that the food pieces, freezing gas, and adjuvant are retained within the container. 
     After being placed within the container, the solid freezing gas sublimates to its gaseous state and inflates the container enclosing the food pieces, adjuvant and freezing gas. The inflated containers are then tumbled using a suitable mechanism, intermixing the food pieces, adjuvant and freezing gas. This tumbling step allows the adjuvant to contact the food pieces and adhere to the surface moisture to evenly coat the food pieces. The tumbling step also serves to complete the freezing of the food pieces as they are coated with the adjuvant by mixing all of the food pieces into contact with the freezing gas. 
     While the freezing gas continues to freeze the coated food pieces, the gas leaks out of each container through the porous end section of the container. This allows the container to deflate as it is tumbled, consequently reducing the size of the container enclosing the coated frozen food pieces. 
     Because most of the freezing gas has leaked through the porous end section by the completion of the tumbling step, the container can be resealed below the porous end section to effectively prevent any gas or moisture from entering the container. The porous end section is then trimmed from the container, and the container can be placed in a storage freezer for later shipment and sale. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     In the drawings: 
     FIG. 1 is a side elevation view of a plastic container utilized in the method of the present invention; 
     FIG. 2 is a cross-sectional view along line  2 — 2  of FIG. 1 illustrating the construction of the plastic container; 
     FIG. 3 is a cross-sectional view similar to FIG. 2 illustrating an alternative construction of the plastic container of FIG. 1; 
     FIG. 4 is an isometric view of a carousel which supports a number of plastic containers during various steps of the method of the present invention; 
     FIG. 5 is a schematic representation of the steps of the method of the present invention; 
     FIG. 6 is a side elevation view of the plastic container of FIG. 1 including a first seal; 
     FIG. 7 is a cross-sectional view along line  7 — 7  of FIG. 6; 
     FIGS.  8 ( a )- 8 ( d ) are sequential side elevation views illustrating the process in which the sealed plastic containers of FIG. 7 are tumbled according to the method of the present invention; 
     FIG. 9 is a side elevation view of the plastic container of FIG. 6 including a second seal disposed beneath the first seal; 
     FIG. 10 is a cross-sectional view along line  10 — 10  of FIG. 9; and 
     FIG. 11 is a side elevation view of the plastic container of FIG. 9 with the first seal on the container removed from the container by a cut through the second seal. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Wherein like reference numerals designate like parts throughout the disclosure, a container  12  utilized in the present invention is disclosed in FIG.  1 . The container  12  is generally a plastic bag formed of a thermoplastic material. Preferably, the container  12  is a laminated bag comprising an outer layer  14 , an intermediate layer  16 , and an inner layer  18 . The outer layer  14  is formed of a printable thermoplastic material to which various labels can easily be affixed. The intermediate layer  16  is a gas-impermeable layer that prevents air and moisture from penetrating into the container to minimize the effects of freezer storage. The inner layer  18  is a thermoplastic layer capable of fusing to the intermediate and outer layers to form the container  12  that also functions as a liner for the interior of the container  12 . 
     The container  12  has a generally rectangular shape shown in FIG. 1, but can be formed to have almost any shape desired. The container  12  is formed by sealing a pair of generally rectangular sheets of the laminated thermoplastic layers by sealing to one another along both sides and at one end to form a container  12  having an interior space  19  and an open end or mouth  20  as shown in FIG.  2 . At the end of the container  12  forming the mouth  20 , the intermediate layer  16  does not extend completely to the end of the container  12  forming the open end  20 . At the open end  20 , the outer layer  14  and the inner layer  18  are joined directly to one another and form a pair of porous end pieces  22  at the open end  20 . Therefore, when the container  12  is sealed at the open end  20  by joining the porous end pieces  22 , a gas contained within the container  12  may pass through the joined porous end pieces  22  to the outside atmosphere. 
     An alternative construction of the container  12  is shown in FIG.  3 . In this construction, the container  12  is formed with the outer layer  14 , intermediate layer  16 , and inner layer  18  similarly to the previous construction. However, in this construction, the intermediate layer  16  is coextensive with the outer layer  14  and inner layer  18 , and a pair of sections of a separate, porous material  24  are laminated to the inner layer  18  at the open end  20  along both sides of the container  12 . The porous material pieces  24  extend outwardly from the open end  20  and can be sealed directly to one another to form the porous end piece  22  for the container  12 . 
     The method in which the container  12  is used to prepare a frozen food product is illustrated in FIGS. 4-11. In the method, a generally circular carousel  26 , shown in FIG. 4, is used to move each of the containers  12  through various steps of the method. The carousel  26  includes a plurality of pairs of hooks  28  disposed about its circumference that are used to retain individual containers  12  on the carousel  26 . In operation, the carousel  26  rotates in a counterclockwise direction to move the containers  12  on the hooks  28  to a number of different stations where different steps of the method are performed. 
     FIG. 5 schematically illustrates the various steps performed during the entire method for preparing the food product as the containers  12  rotate on the carousel  26 . First, a number of the containers  12  are placed onto each pair of hooks  28  on the carousel  26  at a bag placement station  30 . At this station  30 , the open mouth  20  of the outermost container  12  on each pair of hooks  28  is folded back over the container to widen the open mouth  20  to better accept material into the container as the carousel rotates through the various stations. 
     The carousel  26  then rotates to position the container  12  at a weighed product filling station  32 . At this station  32 , an amount of a food product (not shown) is placed within the container  12 . The food product can be placed within the container at filling station  32  in a variety of ways, such as by manually scooping the product into the container  12  or by using a volumetric filling machine (not shown). 
     The food product that is weighed and placed into the container  12  at station  32  comprises an amount of precooked food pieces (such as peas, carrots, meat, potatoes, and the like) prepared in a process similar to that disclosed in Montgomery et al U.S. Pat. No. 4,478,861, incorporated herein by reference. Initially, the food pieces are cooked to a fully prepared state in the presence of water at a cooking station  34 . Subsequently, the remaining free water is removed at station  36 , via a process known in the art, leaving the food pieces moist but with voids in the food pieces. Alternatively, the free water removal station  36  can be omitted by cooking the food pieces at cooking station  34  until all of the water present is either absorbed by the food pieces or has evaporated. The food pieces are then moved through a continuous freezing unit  38  that partially freezes the food pieces to rigidify them, while leaving a small amount of unfrozen moisture on the different surfaces of each food piece. From there, the partially frozen food pieces are transferred to the weighed product filling station  32  for placement within the containers  12 . 
     As the carousel  26  rotates away from the filling station  32 , the container  12  arrives at a freezing gas station  40 . At this station, an amount of a freezing gas (not shown) is placed within the container  12  along with the partially frozen food pieces. The freezing gas preferably takes the form of solid carbon dioxide (CO 2 ), but may also be any suitable inert gas that sublimates directly from a solid state to a gaseous state. Most preferably, the solid CO 2  is placed within the container  12  as CO 2  snow manually discharged from a CO 2  horn (not shown). The horn converts liquid CO 2  from a tank (not shown) connected to the horn into the CO 2  snow placed into the container  12 . 
     Once a sufficient amount of freezing gas has been added at station  40 , the carousel  26  rotates further to move the container  12  containing the food product and freezing gas to an adjuvant station  42 . At this station  42 , a measured amount of a dry powdered adjuvant (not shown) is placed within the container  12  holding the freezing gas and weighed food product. The adjuvant can be placed into the container  12  in a manner similar to that in which the food product was placed in the container  12  at the weighed product station  32 . Therefore, the adjuvant may be placed into the container  12  either manually or by some type of volumetric filling machine (not shown). The amount of adjuvant added to the container  12  corresponds to the amount of food product within the container  12 . Because the amount of food product in the container is known to a high degree of certainty, an appropriate amount of adjuvant can be placed in the container with the food product to more closely and accurately control the seasoning of the food product and consequently prevent either under- or over-seasoning of the food pieces from occurring. 
     Once the adjuvant has been added to the container  12 , the carousel  26  rotates to position the container  12  at a bag removal station  44 . At this station, the outermost containers  12  holding the food product, freezing gas, and adjuvant are removed from the hooks  28  on the carousel  26 , exposing another container  12  to be filled in the same manner. The bags are then placed into a heat sealer (not shown) at a first sealing station  46  to close each container  12  by heat sealing the open end  20  to form a first seal  47  on each container  12  as shown in FIGS. 6-7. The first seal  47  effectively encloses the food product and adjuvant within the interior space  19  of the container  12  by sealing the porous end pieces  22  on the container  12  to one another. The heat sealer located at the first sealing station  46  may be a manual sealer whereby each container  12  is individually positioned within the sealer and sealed, or may be a mechanical sealer in which the containers  12  are placed on a conveyor belt (not shown) such that the open ends  20  of the containers  12  continuously pass through the sealer disposed on one side of the conveyor belt. 
     When the containers  12  are sealed, the subliming freezing gas present within each container  12  inflates the container as the freezing gas changes from a solid to a gaseous form. As the container  12  is inflated by the freezing gas, the food products and adjuvant within the interior space  19  of the container  12  are free to move about the expanded interior of the container  12 . 
     After the open end  20  of each container  12  has been sealed, the container  12  is transported to a tumbling station  48 . At the tumbling station  48 , the container  12  is tumbled, or agitated, such that the food product, adjuvant and freezing gas contained within the now inflated container  12  move about the interior of the container. The tumbling process allows the adjuvant to adhere to the residual moisture present on the surfaces of the food product. Furthermore, in conjunction with coating the food product with the adjuvant, the tumbling of the containers  12  allows the freezing gas to more effectively contact each of the food product pieces within the container  12  and complete the freezing process. 
     FIGS.  8 ( a )- 8 ( d ) more clearly illustrate the operation of an oscillating staircase mechanism  50  comprising staggered pairs of stationary steps  52  and oscillating steps  54  that is preferably used at the tumbling station  46 . In FIG.  8 ( a ), a container  12  is initially placed on an aligned first pair of steps  52   a ,  54   a  of the oscillating staircase  50 . The first step  52   a  remains stationary throughout the process, while the second step  54   a  is capable of oscillatory motion in a vertical direction. As shown in FIG.  8 ( b ), when the second step  54   a  moves downwardly from its position in alignment with the first step  52   a , the container  12  rolls off of the first step  52   a  in a counterclockwise direction illustrated by arrow A. The container  12  then comes to rest upon the second step  54   a  and third step  52   b  of the staircase that are now in alignment with one another. In FIG.  8 ( c ), the second step  54   a  returns to its original position aligned with the first step  52   a . In doing so, the second step  54   a  rolls the container  12  in a counterclockwise direction indicated by arrow B onto the second pair of steps  52   b ,  54   b  of the staircase mechanism  50 . At the same time, a second container  12  is deposited on the realigned first pair of steps  52   a ,  54   a . While the second step  54   a  oscillates to tumble the second container  12 , the fourth step  54   b  oscillates in conjunction with the second step  54   a , and consequently initials a second tumbling operation on the first container  12  shown by arrow C. The staircase mechanism  50  can consist of as many pairs of oscillating and stationary steps as needed to complete the coating and freezing of the food product contained within each container  12 . 
     While the containers  12  are tumbled on the staircase mechanism  50 , the freezing gas leaks out of the container  12  through the porous end piece  22  as it freezes the food product, allowing the interior space  19  of the container  12  to slowly deflate throughout the tumbling process. Therefore, at the completion of the tumbling process, the amount of freezing gas present within the container  12  is minimal because most of the gas has leaked from the container  12  through the porous end piece  22 . 
     Once the tumbling process is completed, the containers  12  are removed from the bottom of the staircase mechanism  50  and transported to a second sealing station  56 . As shown in FIG. 9-10, a heat sealer (not shown) at the second sealing station  56  forms a second seal  58  on the container  12  between the food product and the first seal  47 . The second seal  58  is spaced inwardly on the container  12  from the first seal  47  a sufficient distance such that the second seal  58  is formed below the porous end piece  22  and above the interior space  19  on a portion of the container  12  including the intermediate gas impermeable layer  16 . The second seal  58  thus effectively seals the interior space  19  of the container  12  from the atmosphere to prevent air and moisture from prematurely entering the container  12 . 
     After the second seal  58  is formed by at the second sealing station  56 , each container  12  is passed to a trimming station  60 . At trimming station  60 , a cutting device (not shown) makes a cut  62  through the second seal  58 . The cut  62  separates a container portion  64 , including the porous end piece  22  and first seal  47 , from the remainder of the container  12  which remains sealed by the portion of second seal  58  remaining on the container  12 , as shown in FIG.  11 . The container portion  64  is discarded and the sealed container  12  may be packaged and shipped for sale to the ultimate consumers. 
     Various alternatives and embodiments are contemplated as being in he scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.