AU4575102A - Food treating device - Google Patents

Description

Via Fax 0061 2 6283 7999 31 May 2002 THE COMMISSIONER OF PATENTS: Applicant, Natureland Foods Limited, a New Zealand Company, prays that Letters Patent be granted to it for the new and useful FOOD TREATING DEVICE set forth in the following specification: *0 0

PATENT

SPECIFICATION

Background of the Invention Field: The invention is in the field of treating and conveying apparatus, particularly food cooling or heating apparatus.

State of the Art: Various types of fluidized bed conveying apparatus are known as are various types of food cooling, freezing, heating, and cooking apparatus wherein food products are cooled or heated while being conveyed through the apparatus. An example of a combination of such apparatus is a fluidized bed dryer which utilizes a hot air stream passing upwards through a directional oscillating or vibrating perforated plate onto which is fed a stream of particles to be dried, the air stream lifting and passing around and between the particles causing a transfer of heat from the air stream to the particles and a transfer of moisture from the particles to the air stream.

Freezing apparatus is also known wherein a continuous upward spiraling mechanical conveyor conveys various random shaped products in a spiral path through a housing containing refrigerated air. The products freeze while being conveyed. Typically, a freezer of this type is very space and heat transfer inefficient and expensive to build.

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Summary of the Invention According to the invention, a treating apparatus particularly useful for treating food items includes an inclined track or trough having perforations through which air or other gas flows to lift and support an item as it moves down the track. The air or other gas also treats the item as it moves down the track, for example by heating or cooling the item. While the track could take various configurations, such as a back and forth flow, it is currently preferred that the track have a spiral configuration. The apparatus works well as a freezing device with refrigerated air used to support and treat (cool and freeze) the items as they flow down the track. The apparatus can also be used to cook items by using hot air of appropriate temperature rather than refrigerated air.

A preferred embodiment of the invention, when used as a continuous freezer, consists of a spiraling trough into which items to be frozen are fed in at the top, with thw items then spiraling downwards in the trough in a circular path. A pressurized gas or air stream is forced into a continuous cavity or plenum chamber under the spiraling perforated plate bottom of the continuous spiraling trough, floating the items above the perforated plate.

The spiraling trough follows a continuous downward path which the individual pieces or items of product being treated follow; being 2 conveyed by gravity and supported by floating on the pressurized air or gas stream in a near frictionless travel until the product reaches the bottom of the spiral. With treatment completed, the items pass out of the spiral and are conveyed out of the apparatus by a straight extension of the spiral conveying means.

The spiral conveying apparatus forms a "spiral drum" enclosure in which a fan is placed to provide circulating gas and to provide pressure in the chamber under the spiraling perforated plate. This fan is preferably a centrifugal fan on a vertical shaft extending up and into the center of the spiral drum. The gas enters a duct leading into the center of the centrifugal fan rotor where it is forced into the open area forming a pressure chamber inside the spiral drum, then into the plenum chamber and through the perforated plate in the product trough, and around the product being conveyed and treated. When the apparatus of the invention is being used as a freezer, the gas may be injected liquid cryogenic S: gas such as liquified carbon dioxide or may be conventional refrigerated air. When used as a baking or drying device, it may be operated with hot or ambient air. The apparatus may contain a heat or refrigeration source or heated, refrigerated, or cryogenic gas may be fed to the apparatus or the apparatus may be located in a refrigerated or heated compartment, space, or room. The gas may be recirculated or merely exhausted. The fan which supplies the 3 o:o pressurized air stream to the spiral is preferably located inside the box and inside the spiral drum but may be located externally.

The invention may also be used as a dehydrator whereby a dry air stream is used instead of heated or cooled gas.

The Drawings The best mode presently contemplated for carrying out the invention is illustrated in the accompanying drawings, in which: Fig. 1 is an end elevation of a treatment device of the invention; Fig. 2, atop plan view taken on the line 2-2 of Fig. 1; Fig. 3, a vertical section taken on the line 3-3 of Fig. 2; Fig. 4, a transverse section taken on the line 4-4 of Fig. 1; Fig. 5, a side elevation taken on the line 5-5 of Fig. 1; Fig. 6, an opposite side elevation taken on the line 6-6 of Fig. 1; Fig. 7, a fragmentary vertical section of the track or trough taken on the line 7-7 of Fig. 1; Fig. 8, a fragmentary vertical section similar to that of Fig.

7 but only showing three levels of the trough and showing a second embodiment of the trough; and oeo•

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*5SS Fig. 9, a vertical section through an end of the trough taken on one of the lines 9-9 of Fig. 2, showing the inlet portion of the trough or outlet portion of the trough.

Detailed Description of the Illustrated Embodiments In the embodiment of the invention shown in the drawings, a wall 20 forms a generally vertically oriented cylindrical inner housing indicated generally at 21 with a spiral track or trough 22 secured around the outside thereof. The cylindrical inner housing forms a pressure chamber for treating gas which enters the chamber through gas inlet 23 to a fan 24 secured to motor shaft extending from motor 26 which rotates the fan to draw treating gas in through inlet 23 and pressurize it in pressure chamber 27.

Cylindrical inner housing 21 has a floor 30 which seals the bottom of the chamber. Support braces 31 extend from the floor upwardly to secure and support cylindrical inlet walls 32 and inlet

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funnel walls 33 also secured in sealing manner to a sealing top wall 34. Bracket 35 secured between floor 30 and support 31 provides a secure mount 36 for motor 26. An electrical wire 37, Fig. 3, extends from motor 26 through grommet 38 in wall 20 to outside the inner housing 21 for connection to a conventional motor control and source of power, not shown. The motor control preferably provides for variable speed control of the motor for .o fine tuning of the volume of air flow (also affects the speed of air flow) through the apparatus.

Inner housing 21 is supported on structural channels 40 with floor reinforcements 41. Motor 26, while shown within housing 21, may be located outside of housing 21 with a drive shaft either directly from the motor or coupled to the motor to drive the fan 24.

Troughs 22 include a perforated bottom plate 50, Figs. 3, 4, and 7, with perforations 51, and an outside side plate 52. Side plate 52 extends below perforated bottom 50 to form a side of a plenum chamber 53 which has a bottom 54 which also forms a top for the trough immediately below it. For the top tier spiral trough, a top 55 is provided.

Plenum 53 communicates with pressure chamber 27 through spiral opening or slit 56 in wall 20. Wall 20 is reinforced through the height of spiral opening or slit 56 by braces 57. Thus, pressurized treating gas from pressure chamber 27 passes through o slit 56 into plenum chamber 53 and then through perforations 51 in .perforated plate 50 and out through an outer trough side opening 58. Trough 22 is reinforced by bottom braces 60 and side braces 61.

Trough 22 is generally provided with an inlet portion 65 Figs.

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2, 5, and 6, and an outlet portion 66 which extend tangentially to .6 6

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C the cylindrical housing 21 at the top and bottom of the trough. In order to provide a treating gas supply to support the items in the trough in the inlet and outlet portions of the trough, plenum chamber 53 is continued to the ends of the inlet and outlet portions as shown. However, as shown in Fig. 9, since the inlet and outlet portions do not remain immediately adjacent housing wall Figs. 2, 5, and 6, there is no side connection to the pressure chamber. The pressurized treatment gas in the inlet and outlet portion plenum flow from the remaining part of the plenum.

In use, an item to be treated, such as a food item, is placed in the trough at the inlet, such as by a conveyor belt or other equipment. The item is supported in the trough by treatment gas flow through the perforations in the perforated trough bottom and the item slides by gravity, guided by the trough walls, down the track. The item is removed from the outlet portion such as by sliding off the outlet end of the trough onto a conveyor belt or other conveying apparatus where the item is moved, for example, to packaging apparatus or to storage. A gate or other stoppage means may be provided at the outlet or at other locations along the trough to stop the flow of items down the trough when desired to ensure that the items remain in the trough for the desired retention treatment time.

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o 0 7 As shown by Fig. 7, treating gas from pressure chamber 27 passes through slit 56 into the plenum chamber 53 as shown by arrows 70. From plenum chamber 53, the treating gas passes through perforations 51 in perforated trough bottom 50 as shown by arrows 71 to support an item 72 to be treated above trough bottom 50 in a manner so item 72 slides down the trough. Side 52 keeps item 72 in the trough during its slide. While in the trough, treating gas flows under, around, and over item 72 as shown by arrows 73. The treating gas then flows out through opening 58.

Although the percentage of open area in the perforated plate typically is more than 20% in fluidized bed drying, the percent of open area in the perforated plate of the present invention is preferably in the range of about to 20% depending upon the configuration and weight of the product being conveyed through the invention. Open areas making up about 5% have been found to work wel with most products. The air volume will be typically less S.i: than that required for drying free flow products in a fluidized bed dryer.

As shown in Fig. 8, if desired, additional perforations 80 may be provided in trough wall 20 just above trough bottom 50 to provide additional treating gas flow against a side and over the top of the item 72 to be treated as shown by arrows 81.

8 S. Fig. 9 shows air flow in the inlet and outlet portions or extensions of the trough where there is no connection along the side to the pressure chamber but treating gas merely flows through the plenum chamber.

Treating gas may be exhausted to the atmosphere through slit 58 or the apparatus may be placed in a housing such as shown schematically by broken lines 85 in Fig. 3 so that the treating gas is collected in the housing and recirculated through the apparatus.

In such situation, provision is made for the entrance to and exit from the housing of items to be treated. A similar situation is present where the apparatus is located in a special environment such as in a freezer, blast freezer, or hot room. Additional treating gas is fed into the housing through an inlet 86 when needed. Venting of the apparatus may be into the atmosphere but is preferably directed out through a product inlet or outlet where it may be used to help convey product into or out of the apparatus, and if in the inlet, may also be used to pretreat product items such as to pre-chill the product, reducing freezer costs and the retention time in the freezing apparatus.

Gas entering apparatus inlet 23 may be treated such as with the addition of cryogenic gas or liquid such as liquified CO 2 or nitrogen as it enters or the apparatus may have heating or cooling oo or other conditioning equipment in the apparatus. The use of 9 go5 S S nitrogen gas as the treatment gas has the advantage that nitrogen has preserving qualities in packaging, with vented gas being used in producing a gas flushed package. The product items leaving the apparatus would have had all or nearly all oxygen removed while traveling through the treatment trough with the nitrogen acting as a preservative. The external product conveying means may also be housed to obtain further use of the vented gas.

In the following example, using an early prototype apparatus providing a similar spiral gravity feed track and air flow around the items, a pastry product is frozen using the apparatus of the invention. The criteria is as follows: Compressed carbon dioxide is used as the freezing means, i.e., the treatment gas. It is injected into the air stream inside the enclosure. In this product treatment, the product is a cheese sandwich and each item weighs about 80 grams. The product consists of two slices of bread with cheese inside. The crust of the bread has been removed and the edges crimped to seal the sandwich. The 20mm thick x 100mm x 100mm product is fed into the invention at a rate of one unit about every second which is a rate of about 3600 units per hour. The temperature of the product going in is about 0 C. The retention time in the invention is about 13 minutes.

The temperature in the freezer varies from about -25 0 C to about *1 ego gOOD S. S°°5 -401C, (in general for freezing, the temperature in the freezer can range bertween about -15 0 C to about -800C depending upon the product); the temperature of the gas on the inlet side of the spiral drum being lower than on the exit side. The product has a quilted pattern embossed into each side which presents a very irregular surface to the perforated plate and increases the density of the sandwich to enhance the freezing efficiency. The sandwich on exiting the invention has an equilibrated temperature of about -17 0 C. The fan supplying the air to the chamber inside the spiral drum generates a pressure under the perforated plate of about 3" water gauge; the spiral trough is about 106mm wide and about meters long consisting of 20 tiers. The perforated plate has about dia perforations on about 9mm centers. The circulating gas throughout is about 18000 cfm.

Design criteria of the apparatus will vary with the quantity, size, weight, density and configuration of the product to be

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treated. These design variable are: size and length of product conveying trough in the spiral; size and centers of perforations in the trough bottom; temperature, volume and pressure of air needed in the apparatus with appropriate fan size and pressure ability; type of gas circulated within the invention; total lineal length of the trough; pitch of the trough for conveying the product; volume of gas passing through the spiral drum; retention time in the

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trough; space available for locating the apparatus which dictates the configuration of the apparatus (for example, a straight trough or spiral) and whether a housing is part of the apparatus or is an existing freezing room. .Other design changes may be considered in tailoring the apparatus to the product to be treated but it is emphasized that the basic principle of the invention does not vary.

That is floating a solid or relatively impervious product on an air stream with the same air stream acting as the product treating medium while simultaneously providing a relatively friction-free conveying means; the product being moved along the trough by either gravity (as in a sloping trough in a spiral configuration) or by jets of the treatment gas inside the trough directed laterally onto the product in the direction of travel (or both). Said jets may be located either above, below or on the side of the product conveying trough. A diameter of about five feet for the spiral trough has been found satisfactory, but other sizes may be used or preferred in specific instances.

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se In addition to perforations in the bottom of the trough and in Sthe side, if desired, perforations may also be provided in the top of the trough so treatment gas is directed downwardly, either straight or at a lateral angle, onto the items to be treated. If at an angle, this can provide additional lateral force to assist in oooo moving the items along the trough and in all events, provides SOO1 12 0@55 0 0 additional treatment gas to the product to speed treatment and provide more uniform treatment to both top and bottom of the item.

It has been found when freezing items, that an air velocity around the items of at least about fifty mph tends to strip away a warm layer encompassing the product for faster freezing. For example, in a conventional freezer a pot pie takes about one-andone-half hours to freeze while in the invention, the same pie is frozen in less than one hour. The apparatus of the invention is effective because the product being treated is very close to the treating gas exiting the perforations in the bottom of the trough.

The items be treated may be elevated from about one-sixty-fourth inch to about one-eighth inch above the bottom of the trough. With the apparatus of the invention operating as a freezer, a four ounce beef patty which in the best prior art freezers takes about three minutes to freeze, takes less than two minutes to freezer.

Although the trough is preferably built in a spiral S. configuration, it could take a variety of other configurations such as a stack of troughs in a straight line which operate in the same oB*e basic manner but transfer the product by gravity from top tier progressively onto the next tier below where the direction is reversed until the treated product is passed out of the apparatus when reaching the bottom tier. The conveying apparatus may also be eliptical, a modified square, rectangular, or of various other 13 e* shapes. The trough may be continuous or broken at intervals.

Also, while it is presently preferred to have a pressurized cylindrical drum to supply treatment gas to the trough, the flow of pressurized gas to the trough may be from the outside periphery or various other arrangements of conduits for supplying the treatment gas may be used.

In another example of the use of the invention, the same apparatus used to freeze sandwiches is used to bake cookies. In this example cookie dough is rolled into a sheet. Cookies diameter are cut out of the sheet and fed into the spiral trough.

The gas in the apparatus is air heated to about 130 0 C. The retention time in the apparatus is about 12 minutes and the baking rate is about 20,000 cookies per hour. An adjoining like apparatus is used to cool the cookies produced in the heating apparatus. The cooling being accomplished by pulling ambient atmospheric air through the fan pushing it through the spiral drum.

This invention also consists of a method, described as follows, for making specific food products which use the apparatus as a step in their manufacturing process: i1. SANDWICH MANUFACTURING METHOD A. Assemble two or more slices of bread with a filling "between the slices.

.oo*14 o*O B. Place the sandwich in the subject invention apparatus (which contains below freezing air) where it is frozen thereby bonding together, by the action of freezing, the layers of bread and filling allowing the sandwich to be handled and packaged without falling apart.

2. PASTRY PROCESSING

METHODS

Method for providing a pastry product: A. Mix the described ingredients of the pastry into a pliable dough.

B. Form into flattened pieces.

C. Place the pastry pieces into the subject invention which contains air or gas heated to the appropriate temperature for proving the pastry which is retained until proved.

Method for baking a pastry product while maintaining an identical pattern or surface texture on both sides: The steps are the same as the above pastry proving method except the temperature in the subject invention contains air or gas heated to the appropriate temperature for baking the pastry which is retained until baked.

a°o o Method for cooling a pastry product: The method is the same as step C. in the proving or baking method except that ambient or cooled air is used in the invention as a cooling means. The air is not recirculated. The product is retained until cooled.

3. METHODS FOR PROCESSING FORMED MEAT. VEGETABLE OR SEAFOOD CAKES Method for cooking subject formed food cakes: A. Form the food into cakes or shapes which offer the maximum practical surface area and best shape for floating on the air stream.

B. Apply a coating to the formed pieces if desired.

C. Place pieces to be cooked in the subject apparatus invention which contains air or gas heated to the desired temperature for cooking. Retain until cooked.

o Method for cooling subject food cakes: Place pieces to be cooked in the subject apparatus invention which uses ambient or chilled air for cooling. Retain until cooled.

.e 16 .o* Method for freezing subject food cakes: Place pieces to be frozen in the subject apparatus invention which contains air or gas at the desired below freezing temperature. Retain until frozen to desired temperature.

4. METHOD FOR FREEZING PACKAGED FOOD PRODUCTS A. Fill packages such as sachets, small free flow containers of butter, jam or other such foods or slabs of wrapped foods such as butter, seafoods, vegetables or the like.

B. Place the packaged food to be frozen in the subject apparatus invention which contains air or gas at the desired below freezing temperature. Retain until frozen to desired temperature.

The subject invention is very useful in treating products by proving, heating, baking, drying, cooking, conveying, cooling, or S. freezing; when such products tend to stick to surfaces or distort until treated. The use of the invention is valuable in its ability S to float any properly shaped product on an air stream while the

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product is being treated or processed; thereby avoiding contact with any hard surface until treated. It makes possible the preserving of a special texture or embossed pattern or coating on a product, an example is cookies which can be produced with an 17 identical pattern and color on both sides rather than a pattern on one side and a flattened darker opposite side. A method for baking cookies in this manner, using the subject invention, is an invention and a part of this patent application.

Whereas this invention is here illustrated and described with reference to embodiments thereof presently contemplated as the best mode of carrying out such invention in actual practice, it is to be understood that various changes may be made in adapting the invention to different embodiments without departing from the broader inventive concepts disclosed herein and comprehended by the claims that follow.

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Claims (15)

1. 2. A treating apparatus according to Claim i, additionally including a trough top to guide treating gas over the top of the item.
2. 3. A treating apparatus according to Claim 2, wherein the trough forms several tiers one above the other and the plenum .1 19 chamber includes a plenum chamber bottom wall, the plenum chamber bottom wall of one tier forming the trough top for the tier below.
3. 4. A treating apparatus according to Claim 2, wherein a side is also perforated. A treating apparatus according to Claim 3, including a treating gas exhaust opening along one side.
4. 6. A treating apparatus according to Claim i, wherein the trough is in the form of a spiral.
5. 7. A treating apparatus according to Claim 6, wherein the means for supplying treating gas to the plenum is a fan within a housing which creates a pressure chamber which communicates with the plenum chamber to supply treating gas thereto. *ooooa
6. 8. A treating apparatus according to Claim 7, wherein the S: housing creating the pressure chamber is cylindrical and the spiral trough is secured to the housing.
7. 9. A treating apparatus according to Claim 8, wherein the housing forms a side of the trough. A treating apparatus according to Claim 9, wherein the side formed by the housing is perforated to allow air flow into the trough from the side.
8. 11. A treating apparatus according to Claim 1, wherein the perforations make up between about 0.5% and about 20% of the bottom of the trough.
9. 12. A treating apparatus, comprising: a trough having an upper end and a lower end, said trough including; a perforated bottom through which a treating gas flows to support an item to be treated above the bottom of the trough; sides to guide an item moving along the trough, and guide the treating gas about sides of the item; .oe a plenum chamber under the perforated bottom and communicating therewith; an inlet at one end of the trough for receiving o~to items to be treated; and an outlet at the other end of the trough for discharging treated items after traveling down the trough; .2 21 99 o 9 oooo 9o means for supplying treating gas to the plenum; and means for causing items placed at the inlet of the trough to move along the trough to the outlet of the trough.
10. 13. A treating apparatus according to Claim 12, wherein the means for causing items to move along the trough is means for inclining the trough so items being treated and elevated above the bottom of the trough move along the trough by gravity.
11. 14. A method for treating an item with treating gas comprising the steps of: placing the item in a trough having a perforated bottom, sides, and a top; forcing a treating gas through the perforated bottom at a velocity and volume sufficient to elevate and float the item above the bottom of the trough so the item can move along the trough and sufficient to treat the item as desired as the treating air flows against the bottom, around the sides, and over the top of the item; leaving the item in the trough for a period of time sufficient to complete the desired treatment; and removing the item from the trough after completion of the S desired treatment. 22 S° S S S A method according to Claim 14, wherein the velocity of the treating gas flowing through the bottom perforations and impinging on the item to be treated is at least about 50 mph.
12. 16. A method according to Claim 14, wherein the velocity and volume of treating gas is sufficient to elevate the item between about one-sixty-fourth and one-eighth inch above the bottom of the trough.
13. 17. A method according to Claim 14, wherein the item is moved from an inlet to the trough to an outlet from the trough during treatment of the item.
14. 18. A method according to Claim 17, wherein the trough is inclined so that the item moves from the inlet to the outlet by force of gravity. r S** o S
15. 19. A method according to Claim 14, wherein the desired treatment of the item is freezing the item and the step of supplying treating gas includes supplying treating gas of a sufficiently low temperature to freeze the item while in the track. 23 0 0 A method according to Claim 14, wherein the desired treatment of the item is cooking the item and the step of supplying treating gas includes supplying treating gas of a sufficiently high temperature to cook the item a desired amount while the item is in the track. .0 S0. 0 0000 00.0 j