Apparatus for producing a curly puff extrudate

Apparatus for cutting a puff extrudate utilizing a blade that passes through the extrudate while the extrudate is in a viscous melt stage. The present invention utilizes a tube to facilitate production of a curly puff extrudate. A gap is provided in between the tube and the extruder die to allow a blade to access the extrudate as it exits an orifice in the die. The blade accesses the extrudate at the viscous melt stage, before the extrudate has cooled and hardened. The blade nicks the extrudate, as opposed to completely cutting it, which allows the extrudate to remain connected throughout processing such as curling in the containment tube. The gap also allows steam to be vented form the extrudate as it exits the orifice in the die. The nicked extrudate separates when fried or baked.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to the production of a puff extrudate and, specifically, to an improved process of producing a plurality of similarly shaped curly puff extrudate pieces from a single curly puff extrudate.

2. Description of Related Art

The production in the prior art of a puff extruded product, such as snacks produced and marketed under the Cheetos™ brand label, typically involves extruding a corn meal or other dough through a die having a small orifice at extremely high pressure. The dough flashes or puffs as it exits the small orifice, thereby forming a puff extrudate. The typical ingredients for the starting dough may be, for example, corn meal of 41 pounds per cubic foot bulk density and 12 to 13.5% water content by weight. However, the starting dough can be based primarily on wheat flour, rice flour, soy isolate, soy concentrates, any other cereal flours, protein flour, or fortified flour, along with additives that might include lecithin, oil, salt, sugar, vitamin mix, soluble fibers, and insoluble fibers. The mix typically comprises a particle size of 100 to 1200 microns.

The puff extrusion process is illustrated inFIG. 1, which is a schematic cross-section of a die12having a small diameter exit orifice14. In manufacturing a corn-based puff product, corn meal is added to, typically, a single (i.e., American Extrusion, Wenger, Maddox) or twin (i.e., Wenger, Clextral, Buhler) screw-type extruder such as a model X 25 manufactured by Wenger or BC45 manufactured by Clextral of the United States and France, respectively. Using a Cheetos like example, water is added to the corn meal while in the extruder, which is operated at a screw speed of 100 to 1000 RPM, in order to bring the overall water content of the meal up to 15% to 18%. The meal becomes a viscous melt10as it approaches the die12and is then forced through a very small opening or orifice14in the die12. The diameter of the orifice14typically ranges between 2.0 mm and 12.0 mm for a corn meal formulation at conventional moisture content, throughput rate, and desired extrudate rod diameter or shape. However, the orifice diameter might be substantially smaller or larger for other types of extrudate materials.

While inside this orifice14, the viscous melt10is subjected to high pressure and temperature, such as 600 to 3000 psi and approximately 400° F. Consequently, while inside the orifice14, the viscous melt10exhibits a plastic melt phenomenon wherein the fluidity of the melt10increases as it flows through the die12.

It can be seen that as the extrudate16exits the orifice14, it rapidly expands, cools, and very quickly goes from the plastic melt stage to a glass transition stage, becoming a relatively rigid structure, referred to as a “rod” shape if cylindrical, puff extrudate. This rigid rod structure can then be cut into small pieces, further cooked by, for example, frying, and seasoned as required.

Any number of individual dies12can be combined on an extruder face in order to maximize the total throughput on any one extruder. For example, when using the twin screw extruder and corn meal formulation described above, a typical throughput for a twin extruder having multiple dies is 2,200 lbs., a relatively high volume production of extrudate per hour, although higher throughput rates can be achieved by both single and twin screw extruders. At this throughput rate, the velocity of the extrudate as it exits the die12is typically in the range of 1000 to 4000 feet per minute, but is dependent on the extruder throughput, screw speed, orifice diameter, number of orifices and pressure profile.

As can be seen fromFIG. 1, the snack food product produced by such process is necessarily a linear extrusion which, even when cut, results in a linear product. Consumer studies have indicated that a product having a similar texture and flavor presented in a “curl,” “spiral,” or “coil spring” shape (all of which terms are used synonymously by Applicant herein) would be desirable. An example of such spiral shape of such extrudate is illustrated inFIG. 2, which is a perspective view of one embodiment of a spiral or curl shaped puff extrudate20. The apparatus for making curly puff extrudate is the subject matter of U.S. pat. No. 6,722,873 entitled “Apparatus and Method for Producing a Curly Puff Extrudate” and is incorporated herein by reference.

Curly puff extrudate20has proven difficult to cut into smaller, more manageable extrudate pieces. Some type of containment vessel such as a pipe or tube (terms used synonymously by the Applicant herein) is used for the curly puff extrudate production and a cutting device at the end of the tube results in surging and plugging within the tube, particularly during start-up and shutdown of the extruder.FIG. 3illustrates a perspective view of a device involving a number of tubes30attached to a die face18. The exit end of each tube30is attached to an extruder face23. This arrangement then permits the attachment to the extruder face23of a circular cutting apparatus24having a number of individual cutting blades26. Such an arrangement is shown with ten tubes30connected to a die face18. Although not shown inFIG. 3, the tube30and extruder face23configuration can be designed such that the dies12are allowed to vent until specific conditions are met (such as extrudate bulk density, specific mechanical energy, moisture content, screw speed, and die pressure), then the tube30can be rotated over the dies12by device of an additional rotatable plate (not shown) between the tubes30and the dies12.

However, cutting the curly puff extrudate20at the end of the tube30in a multiple tube30assembly is not preferable because the cutting blades26drag the curly puff extrudate20from one tube30to another which results in jagged and non-uniform ends of individual curly puff extrudate20pieces.FIG. 4is an example of a piece of curly puff extrudate20cut with a device similar to the one inFIG. 3. Additionally, when the curly puff extrudate20is produced in a multiple tube assembly, the tubes may not produce extrudate at the same rate, so a single cutter cutting multiple tubes will produce curly puff extrudate pieces of differing lengths.

This problem can be overcome by completely severing the extrudate at the die face when it is in the plastic melt state rather than the glass transition state. However, severing the extrudate at the die face disconnects the individual extrudate pieces and it is sometimes preferable to keep the extrudate connected for processing before separating the extrudate into individual extrudate pieces. Examples of processing include: conveying, seasoning, stretching, separating, or confining the extrudate in a containment vessel. Therefore, a need exists for an effective method of cutting the extrudate in the plastic melt state without completely separating the extrudate

Another problem with the apparatus inFIG. 3is that it does not allow for the release of steam and other hot gasses released from the expanding extrudate. The steam and other gasses promote surging and plugging within the tube. Therefore, a need also exists for an apparatus and method for venting steam and other hot gasses so they cannot enter the containment device.

It should be understood that while a need exist for an apparatus capable of cutting a curly puff extrudate without plugging a containment tube, the need is not limited to curly puff extrudate. A need also exists for an apparatus for cutting a sinusoidal puff extrudate as well as other types of linear and non-linear puffed extrudates.

Consequently, a need exists for an apparatus and method of cutting the puff extrudate into smaller puff extrudate pieces that will create smooth cuts at each end of the individual pieces. A need also exists for an apparatus and method that will prevent plugging of the tube during start-up, operation, and shutdown of the extruder. A need further exists for a method of releasing steam from the expanding extrudate. Moreover, a need exists for an apparatus and method of controlling the length of the individually cut puff extrudate pieces in a configuration with multiple orifices for each die.

SUMMARY OF THE INVENTION

The present invention comprises a nicking blade apparatus that nicks the curly puff extrudate rather than cutting it. The nicks create a series of weak points in the curly puff extrudate. The weak points are strong enough to keep the curly puff extrudate connected during the conveying process. However, when the curly puff extrudate is further processed in an oven or fryer, the curly puff extrudate breaks at the nicks, separating the curly puff extrudate into individual pieces.

In order to properly facilitate the nicking process while the extrudate is in the plastic melt state, the nicking should occur as close to the diehead as possible. The tube is separated from the diehead so that a blade may access the diehead orifice. The resulting separation also allows steam from the expanding extrudate to vent instead of proceeding through the tube. The release of steam allows the curly puff extrudate to flow more smoothly through the tube and helps prevent plugging and surging.

The proposed invention also comprises a tube positioning device that positions the tube over the diehead orifice during operation, but removes the tube away from the diehead orifice during start-up and shutdown. Removal of the tube from over the orifice is desired during start-up and shutdown because the extrudate tends to surge during these periods and plugs the tube. In order to facilitate nicks of different depths, a blade positioning device is also disclosed.

The preferred embodiment of the present invention utilizes a nicking blade for every orifice. However, as some die configurations will not allow a nicking blade for every orifice, a central blade apparatus for nicking multiple orifices is also disclosed.

The preferred embodiment of the present invention also utilizes an oven or fryer to separate the nicked curly puff extrudate. However, under certain circumstances, an oven or fryer is not preferable, so alternate separation devices are also disclosed. Alternative separation devices include a paddle wheel, a vibrating conveyer, and a tumbler.

The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description.

DETAILED DESCRIPTION

FIG. 5is an elevation view of one embodiment of the present invention. Identical reference numerals will be used to identify identical elements throughout all of the drawings, unless otherwise indicated. As with the prior art, the extrudate16exits an orifice14in the die12. The cross-sectional diameter of the orifice14is dependent on the specific dough formulation, throughput rate, and desired rod (or other shape) diameter, but is preferred in the range of 1 mm to 14 mm. (The orifice14diameter is also dependent on the mean particle size of the corn meal or formula mix being extruded.)

If a curly puff extrudate20is desired, a tube30with a flapper32can be used. A flapper32puts pressure on the extrudate16exiting the orifice14so that curls will form in the extrudate16. A tube positioning device34is used to position the tube30in front of or away from the orifice14. The tube positioning device34is capable of moving the tube30in any direction relative to the die12. Examples of tube positioning devices are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. A tube blade36is also affixed to the end of the tube30closest to the die12.

A nicking blade40is positioned flush with the die face18and either rotates or oscillates about a shaft44. The nicking blade40and the shaft44are powered by a motor42, which is connected to a blade positioning device46. The blade positioning device46is capable of moving the motor42, the shaft44, and the nicking blade40in any direction relative to the die12. Examples of blade positioning devices46are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. In order to effectively nick the extrudate16exiting the orifice14, the nicking blade40is positioned such that the end of the nicking blade40only partially covers the orifice14when passing in front of the orifice14. Allowing the nicking blade40to completely cover the orifice14would completely sever the extrudate16, which would not allow the extrudate16to remain connected for additional processing. It should be understood that the extent to which the nicking blade40covers the orifice14determines the depth of the nick in the extrudate16. Deeper nicks will allow the extrudate16to break more easily, a property referred to here as breakability. Shallower nicks will allow the extrudate16to stay connected more easily, a property referred to here as connectivity. The amount of coverage over the orifice14is expressed as a coverage percentage that is equal to the length of the nicking blade40covering the orifice14divided by the orifice14cross-sectional diameter. The coverage percentage desired will depend on the type of viscous melt10and orifice14size. Coverage percentages of eighty to ninety percent have generally been found to be an acceptable balance between breakability and connectivity for the melt10and orifice14size described herein. If desired, the rate at which the nicking blade40nicks the extrudate16can be increased such that the nicking blade40nicks the extrudate16faster than the extrudate16curls. When this is done and the nicked extrudate16is separated, smaller “C” shaped pieces of extrudate are formed.

Another factor affecting the nick size is the nicking blade40tip shape. While pointed nicking blades40are capable of nicking the extrudate16, square edged nicking blades40(i.e. where the edge of the nicking blade40contains two ninety degree angles) have proven more effective at creating uniform nicks in the curly puff extrudate20.

During start up, the tube30is positioned away from the orifice14with the tube blade36placed firmly against the die face18. As the extruder starts and approaches operating parameters, it will extrude undesirable extrudate16. The extruder also extrudes an excess amount of hot gasses, such as steam, from the orifice14during start up. Steam and other hot gasses tend to cause plugging in the tube30. Positioning the tube30away from the orifice14allows the undesired extrudate16to bypass the tube30and prevents the undesired extrudate16, steam, and other hot gases from plugging the tube30. The motor42is generally not run during start up so that the start up extrudate16is not nicked. Alternatively, if the motor42is running, the blade positioning device46can position the moving nicking blade40such that the blade cutting radius22does not cover the orifice14, and the nicking blade40will not nick the extrudate16nor interfere with the positioning of the tube30. In this manner, the motor42and the nicking blade40can be brought up to operating speed without nicking the extrudate16or interfering with the positioning of the tube30. If desired, the nicking blade40can be positioned by the blade positioning device46such that it completely cuts the extrudate16exiting the orifice14. This method cuts the extrudate16into smaller pieces and eliminates the need for a separating device.

FIGS. 6A-6Cillustrate the process of starting up and operating one embodiment of the present invention. When the extruder reaches its operational parameters, the tube positioning device34positions the tube30so that the tube blade36is flush with the die face18(SeeFIG. 6A). The tube positioning device34then quickly slides the tube30across the die face18until the orifice14is within the inside diameter of the tube30(SeeFIG. 6B). When the tube blade36passes over the orifice14, the tube blade36slices off the old extrudate16and allows the orifice14to extrude a new extrudate16into the tube30, where the flapper32will contact the extrudate16and cause it to curl and form the curly puff extrudate20.

After the tube positioning device34positions the tube30over the orifice14, the tube positioning device34moves the tube30away from the die12(SeeFIG. 6C). Separating the tube30from the die face18creates a gap38. The gap38allows gasses such as steam to escape from the expanding extrudate16and allows the nicking blade40to access the extrudate16as it exits the orifice14. Gap distances of 4-8 millimeters have been found to be a good balance between containing the curling extrudate inside the tube30, allowing the nicking blade40access to the extrudate16, and allowing sufficient release of steam. It should be understood that the gap38may vary depending on the pressure and temperature of the extrudate16, the back pressure created by flapper32, and the thickness of the nicking blade40.

It should also be understood that multiple embodiments of the orifice14, the nicking blade40, and the tube30can be implemented on a single die12.FIG. 7is an illustration of a die12with four such embodiments. The blade cutting radius22is defined by the outer reach of the nicking blade40and is shown only partially covering the orifice14. The position of the nicking blade40shown inFIG. 7is preferable to other configurations, such as one in which the shaft44is closer to the edge of the die face18, because the blade cutting radius22does not extend beyond the perimeter of the die face18. Keeping the blade cutting radius22within the perimeter of the die face18helps prevent injury to people working in close proximity to the extruder and the die12. During operation of a die12with multiple orifices14, the extrudate16discharge rate may vary from one orifice14to another. The embodiment utilizing one nicking blade40for every orifice14is preferred because it allows an operator or automated controller to adjust the nicking blade40speed based on the extrudate16output rate and curling rate. By adjusting the speed of the nicking blade40to the output rate of the extrudate16of an individual orifice14, the distance between the nicks on the extrudate16from each individual orifice14can be precisely controlled and thus yield curly puff extrudate20pieces of uniform length.

In certain situations, an embodiment utilizing a nicking blade40for every orifice14may not be necessary or preferable. In these cases, a central nicking apparatus62, as shown inFIGS. 8A,8B, and8C, utilizing a central nicking apparatus positioning device (not shown), a blade positioning device64, and at least one blade60can be utilized. The central nicking apparatus positioning device can move the central nicking apparatus62in any direction relative to the die12. Examples of central nicking apparatus positioning devices62are electrical servo motors, pneumatic actuators, hydraulic actuators, and mechanical screws. A central nicking apparatus62like the one utilized inFIGS. 8A-8Ccan be used to cut or nick a plurality of orifices14.FIGS. 8A-8Care illustrations of the process of positioning the central nicking apparatus62into the center of the die face18such that the blades60of the central nicking apparatus62are able to nick multiple orifices14. InFIG. 8A, the central nicking apparatus62is positioned close to the die face18. A motor (not shown) powers the central nicking apparatus62. As the central nicking device62begins to rotate, the centrifugal force, caused by the rotation of the central nicking apparatus62, forces opens the blades60. The blade positioning device64guides the blades60into position such that they will be parallel with the die face18when completely opened. Alternatively, the blade positioning device64can be actuated or otherwise controlled to force the blades60into position. InFIG. 8B, the centrifugal force continues to expand the blades60and positions them adjacent to the die face18. The nicking apparatus62continues to rotate so that the blades60are moved into position and nick the extrudates16exiting the orifices14(SeeFIG. 8C). The blades60can also be extended far enough to completely sever the extrudates16exiting the orifices14.

Referring back toFIG. 5, after exiting the tube30, the curly puff extrudate20is generally transported to an oven for baking or a fryer for frying. The nicks in curly puff extrudate20are weaker than the rest of the curly puff extrudate20and, consequently, the curly puff extrudate20breaks into individual curly puff extrudate20pieces with little or no mechanical manipulation upon baking or frying.FIG. 9is an example of a nicked curly puff extrudate20piece that has separated in a fryer.

In some applications, it may be desirable to separate the individual curly puff extrudate20pieces prior to baking, frying, or some other processing. In that case, there are a variety of devices that can be used to separate the nicked curly puff extrudate20. One type of separation device is a paddle wheel.FIGS. 10A and 10Bare illustrations of a paddle wheel. In the embodiment disclosed inFIGS. 10A and 10B, the curly puff extrudate20exits the tube30and travels along a conveyer belt, which is parallel to the shaft70of the paddle wheel. The view inFIGS. 10A and 10Bis that of the curly puff extrudate20being conveyed out of the page towards the viewer. Each paddle wheel comprises a shaft70connected to a motor (not shown). A plurality of paddles72are connected to the shaft70. When the shaft70rotates, the paddles72come into contact the nicked curly puff extrudate20(FIG. 10A). By this point, the curly puff extrudate20has cooled sufficiently to harden. When the paddles72come into contact with the curly puff extrudate20, the nicked curly puff extrudate20breaks at its weakest point, namely the nick. The individual curly puff extrudate20pieces then fall into a capture bin underneath the paddle wheel (FIG. 10B). A guide74keeps the curly puff extrudate20from repositioning itself out of the reach of the paddles72.

It should be realized that a paddle wheel is not the only device for separating the individual curly puff extrudate20pieces. A tumbler could be employed to tumble the unseparated curly puff extrudate20until the curly puff extrudate20pieces break off. The curly puff extrudate20pieces could then be removed from the tumbler. The curly puff extrudate20can also be separated on a vibrating conveyer or a conveyer having steps or direction changes that facilitate product separation. Persons skilled in the art will also be aware of various other devices for separating nicked curly puff extrudate20.

While the present invention is disclosed in reference to curly puff extrudate20, it should be understood that the present invention could be employed with cylindrical, uniquely shaped, or any other type of extrudate16. Additionally, the present invention can be utilized any time there is an need for cutting or nicking of a quasi-solid effluent from any type of process.

It should further be understood that more than one die12could be routed into a single tube30. For example, a tube30can receive the extrudate16from two nearby orifices14. Further, dies12producing any number of shapes, such as a star or square cross section or more complex shapes, such as a cactus or pepper shape, can be used with the invention.

Any number of various types of extruders can be used with the invention, including twin screw and single screw extruders of any length and operating at a wide range of rotational speeds. Further, while the process has been described with regard to a corn-based product, it should be understood that the invention can be used with any puff extrudate, including products based primarily on wheat, rice, or other typical protein sources or mixes thereof. In fact, the invention could have applications in any field involving extrusion of a material that quickly goes through a glass transition stage after being extruded through a die orifice.