Method and apparatus for cooling foodstuff

Abstract

A method of cooling foodstuff comprises immersing at least one perforated container containing foodstuff into an ice slurry bath for a period of time sufficient to allow ice slurry to enter the at least one perforated container and then subsequently removing the at least one perforated container from the ice slurry bath. Various apparatuses for cooling foodstuff are also provided.

Claims

1. An apparatus for cooling foodstuff comprising: at least one tank containing an ice slurry bath and adapted to receive a stack of perforated containers containing the foodstuff to be cooled such that the entire stack of perforated containers is immersed in the ice slurry bath; at least one nozzle within said tank configured to receive ice slurry and discharge said ice slurry into said tank; at least one pump configured to draw ice slurry from said ice slurry bath and deliver the ice slurry to said at least one nozzle; at least one agitator immersed in said ice slurry bath, the at least one agitator configured to maintain the ice slurry bath in an agitated state; at least one sensor configured to monitor an ice fraction of the ice slurry bath; and a lift configured to immerse and remove the stack of perforated containers from the ice slurry bath and to position the stack of perforated containers such that a liquid portion of the ice slurry bath drains out of each perforated container back into the at least one tank when the stack of perforated containers is removed from the ice slurry bath, the lift being conditioned to repeatedly re-immerse the stack of perforated containers into the ice slurry bath until a desired volume of ice crystals is trapped in each perforated container, wherein a volume of ice crystals trapped in each perforated container is determined based on a drop of ice fraction of the ice slurry bath measured using output of the at least one sensor.

2. The apparatus according to claim 1 wherein said at least one nozzle is positioned above the ice slurry bath.

3. The apparatus according to claim 2 wherein said at least one nozzle comprises a plurality of spaced nozzles.

4. The apparatus according to claim 1 wherein said stack of perforated containers is oscillated within said tank.

5. The apparatus according to claim 1 wherein the at least one nozzle is a plurality of nozzles at spaced locations.

6. The apparatus according to claim 2 wherein the at least one tank is a plurality of stacked tanks.

7. The apparatus according to claim 6 wherein said at least one pump delivers ice slurry at least to the at least one nozzle of an uppermost tank of said stacked tanks.

8. The apparatus according to claim 7 wherein said at least one pump delivers ice slurry only to the at least one nozzle of said uppermost tank, the nozzles of other tanks of said stack receiving ice slurry from overhead tanks.

9. The apparatus according to claim 8 wherein the at least one nozzle of each of said other tanks receives ice slurry from the tank that is directly thereabove.

10. The apparatus according to claim 6 further comprising an oscillator configured to oscillate said stack of tanks.

11. A method of cooling foodstuff comprising: continuously agitating an ice slurry bath contained in at least one tank; an immersing step comprising immersing an entire stack of perforated containers containing the foodstuff in the agitated ice slurry bath; and a lifting step comprising lifting the entire stack of perforated containers out of the ice slurry bath such that a liquid portion of the ice slurry bath drains out of the stack of perforated containers and back into the at least one tank, such that ice crystals are left trapped in each perforated container of the stack of perforated containers; and at least one step of repeating the immersing step and the lifting step until a desired volume of ice crystals is trapped in each perforated container.

12. The method of claim 11 further comprising oscillating the foodstuff while immersed in said ice slurry bath.

13. The method of claim 11 wherein during the agitating, the ice crystals are tumbled.

14. The method of claim 11 further comprising: treating the ice slurry bath such that the foodstuff is washed and sterilized when immersed in the ice slurry bath.

15. The method of claim 11 further comprising: lifting at least one of dirt and contaminants from the foodstuff by introducing gas bubbles into the ice slurry bath.

16. The method of claim 11 further comprising: varying ice crystals of the ice slurry bath before the at least one step of repeating the immersing step and the lifting step.

17. The method of claim 11 further comprising: changing a chemical composition of the ice slurry bath before the at least one step of repeating the immersing step and the lifting step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments will now be described more fully with reference to the accompanying drawings in which:

(2) FIGS. 1a and 1b are top plan and side elevational views of a prior art container cooling technique;

(3) FIGS. 2a and 2b are side elevational views of an apparatus for cooling product;

(4) FIG. 3 is a side elevational view of an apparatus for chilling product;

(5) FIG. 4a is a side elevational view of another embodiment of an apparatus for cooling product;

(6) FIG. 4b is a side elevational view of yet another embodiment of an apparatus for cooling product;

(7) FIG. 5 is a side elevational view of yet another embodiment of an apparatus for cooling product;

(8) FIG. 6 is a side elevational view of yet another embodiment of an apparatus for cooling product;

(9) FIG. 7 is a side elevational view of still yet another embodiment of an apparatus for cooling product; and

(10) FIG. 8 is a side elevational view of still yet another embodiment of an apparatus for cooling product.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(11) Turning now to FIGS. 2a and 2b, an apparatus for cooling product held in containers, such as for example perforated boxes, is shown and is generally identified by reference numeral 150. In this embodiment, the apparatus 150 comprises an opened top tank 152 filled with an ice slurry bath 154. The ice slurry bath 154 may be produced by one of the ice-making machines described above or may simply be crushed ice and water. Agitators 156 are provided adjacent at least two sides of the tank 152 to maintain the ice slurry bath 154 in the tank in an agitated state thereby to inhibit conglomeration of ice crystals and ensure a general even distribution of ice crystals throughout the ice slurry bath 154. The agitators 156 are in the form of blades on paddles 156a mounted on upright rotating shafts 156b at different elevations. One or more motors (not shown) are coupled to the shafts 156b either directly or via gear trains (not shown) to rotate the shafts. A sensor 158 including a calorimeter is mounted on the tank 152 to sense the ice fraction of the ice slurry bath 154 within the tank 152. When the sensor 158 detects that the ice fraction of the ice slurry bath in the tank 152 has dropped below a threshold level, the sensor provides an output signal which is used to control operation of ice-making equipment so that ice crystals are added to the ice slurry bath 154 thereby to increase the ice fraction until it reaches the desired level. For example, the signal from the sensor 158 may be used to actuate an ice storage and distribution unit such as that disclosed in U.S. Pat. No. 4,912,935 to Goldstein, assigned to the assignee of the subject application, the content of which is incorporated herein by reference, resulting in ice flakes being discharged from the ice storage and distribution unit into the tank 152.

(12) The tank 152 is sized to accommodate a stack of perforated containers filled with foodstuff allowing the entire stack to be submersed in the ice slurry bath 154. In this manner, the foodstuff in a plurality of containers 210 can be chilled simultaneously allowing the apparatus 150 to maintain an effective throughput. During use as shown in FIG. 2a, the stack of the containers 210 is lowered into the tank 152 and immersed in the ice slurry bath 154. Once immersed, ice slurry flows into the containers 210 through the perforations therein until the containers are flooded with ice slurry. Agitation of the ice slurry helps to establish a generally continuous flow of ice slurry through the containers 210.

(13) As stated previously, the foodstuff in the containers 210 acts as a filter trapping ice crystals resulting in the containers becoming packed with ice crystals. The stack of containers 210 is typically allowed to sit immersed in the ice slurry bath 154 for a period of time sufficient to ensure the containers become generally packed with ice crystals. By immersing the entire stack of containers 210 in the ice slurry bath 154 and agitating the ice slurry bath 154, an even distribution of ice crystals within the containers 210 of the stacks is generally maintained.

(14) Following this, the stack of containers 210 is lifted from the ice slurry bath 154 as shown in FIG. 2b, allowing the liquid portion of the ice slurry to drain out of the containers 210 through the perforations and back into the tank 152 as shown by arrow 212, leaving the ice crystals trapped inside the containers 210. In order to immerse and remove the stack of containers 210 from the ice slurry bath 154, a lift (not shown) such as a forklift or a conveyer line is employed.

(15) As will be appreciated, as the ice fraction of the ice slurry bath 154 is monitored by the sensor 158, the amount of ice crystals trapped within the containers 210 can be determined by measuring the drop in the ice fraction of the ice slurry bath upon removal of the stack of containers. In this manner the amount of ice crystals trapped in the containers 210 can be controlled by adjusting the period of time in which the stack of containers 210 is allowed to sit immersed in the ice slurry bath 154, by controlling the extent of ice slurry bath agitation and/or by adjusting the ice fraction of the ice slurry bath.

(16) The volume of the ice crystals trapped inside the containers 210 may be increased by dipping the stack of containers 210 into the ice slurry bath 154 repeatedly. Depending on the foodstuff to the chilled, performance of the apparatus 150 may be further enhanced by varying the ice crystals of the ice slurry bath 154 and/or by changing the chemical composition of the ice slurry bath. For example, salt may be added to the ice slurry bath 154 and/or the ice crystal size may be changed to alter the flow characteristics of the ice slurry bath.

(17) Funnels or traps can also be placed strategically around the stack of containers 210 so that when the stack of containers is lifted from the ice slurry bath, ice slurry flows downwardly through the stack of containers from top to bottom. Proper positioning of such devices helps to achieve a more uniform distribution of the ice crystals throughout the stack of containers. Different distributions of perforations in containers 210 may also be used to effect ice crystal distribution.

(18) If desired, the ice slurry bath may be treated so that foodstuff in the containers 210 is washed and sterilized when immersed in the ice slurry bath 154. For example, ozone, chlorine or other subtle additives may be added to the ice slurry bath. Alternatively, in addition fine gas bubbles may be introduced into the ice slurry bath 154 to lift dirt or other contaminants from the foodstuff.

(19) As will be appreciated, unlike the prior art, the apparatus 150 allows the volume of ice crystals that remains in the containers 210 to be controlled and ensures intimate contact between foodstuff in the containers and ice crystals. The immersion process also inhibits mechanical damage to foodstuff during the icing process, as the foodstuff typically floats in the ice slurry bath 154 during the icing process. In conventional methods, foodstuff may be crushed by ice.

(20) FIG. 3 shows an alternative apparatus 250 for chilling product such as foodstuff very similar to that of FIGS. 2a and 2b. In this embodiment, the apparatus similarly comprises a tank 252 filled with an ice slurry bath 254. Rather than employing agitators, nozzle assemblies 256 are provided adjacent at least two sides of the tank 252. Each nozzle assembly 256 has a series of nozzles 256a pointing inwardly towards the center of the tank 252. A pump 260 has an inlet coupled to a drain adjacent the bottom of the tank 252 and an outlet coupled to the nozzle assemblies 256. In this manner, ice slurry in the tank 252 is circulated from the tank through the pump 260 and to the nozzle assemblies 256. The ice slurry is in turn discharged by the nozzles 256a towards the center of the tank 252 to maintain the ice slurry bath 254 in an agitated state. To enhance distribution of ice slurry, deflectors can be positioned within the tank to direct ice slurry exiting the nozzles 256a either towards or away from the stack of containers. A sensor 258 including a calorimeter is similarly mounted on the tank 252 to sense the ice fraction of the ice slurry bath 254 within the tank.

(21) The operation of the apparatus 250 is virtually identical to that of apparatus 150. Stacks of containers 210 are immersed in the ice slurry bath 254 so that the ice slurry enters the containers 210 resulting in ice crystals being trapped within the containers. As will be appreciated, use of the nozzle assemblies 256 increases the degree of agitation of the ice slurry bath 254 and hence ice slurry flow through the containers 210. This enables the containers to be more densely packed with ice crystals or the throughput of the apparatus to be increased as compared to apparatus 150.

(22) If desired, agitators similar to those shown in FIGS. 2a and 2b can be used in conjunction with the nozzle assemblies 256.

(23) For the embodiments of FIGS. 2a, 2b and 3, rather than employing agitators or nozzle assemblies to agitate the ice slurry bath, the ice slurry bath can also be agitated through movement of the stack of containers within the tank.

(24) Turning now to FIG. 4a, another apparatus for cooling product is shown and is generally identified by reference numeral 320. The apparatus 320 is best suited for chilling foodstuff with high thermal mass and low thermal conductivity. Cooling of such foodstuff requires a longer time and is generally limited not by the heat transfer from the ice slurry, but by the internal flow of heat. As can be seen, the apparatus 320 comprises a plurality of stacked tanks 340a to 340c, each tank of which is filled with an ice slurry bath 342. The ice fraction of each ice slurry bath 342 is adjusted to meet specific cooling and heat transfer requirements by monitoring the ice fraction of the ice slurry bath in each tank using for example sensors of the type described above and introducing ice into the ice slurry baths when appropriate. The temperature of the ice slurry baths 342 can also be adjusted by changing the concentration of temperature depressants in the ice slurry baths 342.

(25) A nozzle assembly 344 having a series of nozzles 344a is provided adjacent the top of each tank 340a to 340c and sprays ice slurry into its associated tank. A pump 350 has its inlet coupled to a drain adjacent the bottom tank 340a and its outlet coupled to the nozzle assembly 344 of the uppermost tank 340c. A conduit 352 extending from the base of the top tank 340c supplies ice slurry to the nozzle assembly 344 of the middle tank 340b under the influence of gravity. Similarly, a conduit 354 extending from the base of the middle tank 340b supplies ice slurry to the nozzle assembly 344 of the bottom tank 340a under the influence of gravity.

(26) During use, foodstuff 360 is placed into the ice slurry baths 342. The foodstuff 360 may have a surface package or by its specific nature, may resist mixing with the ice slurry baths 342. In any event, cooling occurs predominantly by contact between the ice slurry baths 342 and the outer surfaces of the foodstuff 360 and by conduction within the foodstuff 360. To enhance heat transfer between the foodstuff 360 and the ice slurry baths 342, the levels of the ice slurry baths within the tanks 340a to 340c can be varied. Also, small agitation devices can be provided in the tanks 340a to 340c.

(27) If desired, as shown in FIG. 4b, the stacked tanks 340a to 340c can be oscillated as identified by arrow 370 thereby to agitate the ice slurry baths 342 within the tanks. Movement of the foodstuff 360 as a result of the oscillating tanks 340a to 340c, displaces the ice slurry baths 342 helping to improve heat transfer between the foodstuff 360 and the ice slurry baths 342.

(28) FIG. 5 shows yet another apparatus 420 for cooling foodstuff. In this embodiment, the apparatus 420 comprises a tank 422 filled with an ice slurry bath 424. A nozzle assembly 426 having a series of nozzles 426a is provided adjacent the top of the tank 422 and sprays ice slurry into the tank thereby to agitate the ice slurry bath. A pump 428 has its inlet coupled to the bottom of the tank 422 and supplies ice slurry drawn from the tank to the nozzle assembly 426. A support frame 430 is disposed within the tank 422 below the top level of the ice slurry bath 424 and is coupled to a vibrating device 432. The support frame 430 has a plurality of compartments 430a, each of which receives one or more pieces of foodstuff 434. During operation, foodstuff 434 are placed in the compartments 430a of the support frame 430 and the support frame is vibrated via the vibrating device 432. Vibration of the support frame 430 supplements agitation of the ice slurry bath 424 thereby ensuring adequate flow of ice slurry around the foodstuff 434.

(29) If desired, the ice slurry bath 424 can be further agitated by introducing gas bubbles into the bottom of the tank 422. The apparatus 420 is beneficial for the cooling of foodstuff where cross-contamination is a problem, as the support frame 430 supports foodstuff 434 in individual compartments 430a.

(30) Referring to FIG. 6, yet another apparatus 450 for cooling foodstuff 460 is shown. In this embodiment, the apparatus 450 comprises an enclosed tank 470 having an intake port 472 adjacent the top of the tank. The intake port 472 is coupled to a blower 474 that feeds air to an exhaust port 476 adjacent the bottom of the tank 470. An air injection manifold 478 having a series of outlets is positioned adjacent the bottom of the tank 470 and is coupled to the exhaust port 476. An ice crystal inlet port 480 is provided in the top of the tank 470 to allow ice crystals to be supplied into the tank. Air is generally continuously circulated through the tank 470 by the air blower 474 which draws air from the top of the tank 470 via the intake port 472 and returns it to the air injection manifold 478 via the exhaust port 476. The velocity of the air flowing through the tank 470 is selected to be sufficient to maintain the ice crystals in suspension, counterbalancing gravity's effect on the ice crystals, thus creating a fluidized bed 482 of the ice crystals within the tank 470.

(31) During operation, foodstuff 484 is placed in the tank 470 such that the foodstuff is immersed in the fluidized bed 482. Contact between the foodstuff 484 and the ice crystals of the fluidized bed 482 causes the ice crystals to melt resulting in the efficient removal of heat from the foodstuff 484. Melted water is drained from the bottom of the tank 470 via outlet 486 and new ice crystals are generally continuously added to the tank 470 via inlet port 480 to maintain the fluidized bed 482.

(32) If desired, both air and ice crystals may be re-circulated through the air blower 474. In this case, the blower may be used to break ice crystal conglomerations thus ensuring that the fluidized bed 482 consists of homogeneous ice crystals. For example, the air blower 474 construction may be similar to that of a snow blower machine, which breaks, homogenizes, and discharges the ice crystals.

(33) FIG. 7 shows yet another apparatus 620 for cooling foodstuff. As can be seen, in this embodiment the apparatus 620 comprises a tank 640 filled with an ice slurry bath 642. Agitators 644 comprising paddles 644a mounted on rotating shafts 644b are positioned adjacent the bottom of the tank 640 at spaced locations. Nozzle assemblies 650 are provided adjacent at least two sides of the tank. Each nozzle assembly 650 has a series of nozzles 650a pointing inwardly towards the center of the tank 640. Most, if not all of the nozzles 650a are positioned above the ice slurry bath 642. A pump 676 has its inlet coupled to a drain at the bottom of the tank 640 and its outlet coupled to the nozzle assemblies 650. In this manner, ice slurry in the tank 640 can be drawn from the bottom of the tank and discharged back into the top of the tank via the nozzles 650a.

(34) During operation, foodstuff 680 is suspended in the tank 640 above the ice slurry bath 642 and the pump 676 is operated so that the nozzle assemblies 650 spray the foodstuff with ice slurry. As a result, ice slurry is passed over the outer surfaces of the foodstuff 680, with excess ice slurry falling back into the ice slurry bath. Ice crystals coming into contact with the foodstuff 680 melt thereby absorbing heat resulting in the foodstuff 680 being cooled. The presence of the ice crystals in the spray significantly improves the heat transfer in comparison to chilled water or brine.

(35) If desired, a conveyor system can be used to deliver foodstuff 680 into the tank 640 between the nozzle assemblies 650. Also, rather than using nozzle assemblies 650 to spray ice slurry onto the foodstuff 680, the pump 676 can supply an outlet port adjacent the top of the tank 640 which is configured to pour a stream of ice slurry onto the foodstuff 680.

(36) Referring to FIG. 8, still yet another embodiment of an apparatus 820 for cooling foodstuff is shown. As can be seen, in this embodiment the apparatus 820 comprises a tumbler 840 in the form of an inclined, perforated drum having an inlet 842 at one end that receives a mixture of foodstuff and ice crystals. A foodstuff outlet 844 is provided at the opposite end of the tumbler 840. A motor (not shown) is coupled to the tumbler 840 via a gear box 846 to rotate the tumbler 840. A formation such as a spiral or pedals 848 is provided on the interior surface of the tumbler 840 so that when the tumbler is rotated, foodstuff within the tumbler advances along the tumbler from the inlet 842 to the outlet 844.

(37) Contact between the foodstuff and ice crystals within the tumbler 840 causes the ice crystals to melt resulting in the absorption of heat and cooling of the foodstuff. Water resulting from the melted ice crystals is continuously drained from the tumbler via the perforations therein while new ice crystals are added. The rotating and tumbling motion ensures close contact between the foodstuff and the ice crystals. Additional devices to prevent clumping of the ice crystals thereby to improve contact between the ice crystals and the foodstuff may be provided in the tumbler. Also, if desired separate inlets may be provided in the tumbler for the foodstuff and ice crystals.

(38) Although embodiments have been described above with reference to the Figures, those of skill in the art will appreciate that variations and modifications may be made without departing from the spirit and scope thereof as defined by the appended claims.