Patent Application
20070065550
The present invention relates generally to a method and system for making shredded cheese.
Shredded cheese, or cheese in the form of elongated shreds or other shapes, is commonly used as a food topping, such as a pizza topping, etc. Automated conversion of bulk pieces of cheese, such as blocks or loaves, into shreds as part of a continuous operation is technologically challenging. Commercially-available equipment for automated shredding of cheese in high volumes is scarce.
Cheeses, such as mozzarella, that may be relatively elastic in loaf or brick form at ambient conditions can be particularly difficult to form directly into shreds of substantially uniform dimensions. Milling has been used as one way to convert mozzarella loaf into shreds. However, the elasticity of the mozzarella cheese can make milling type shredding difficult to practice. Depending on the process set-up, mozzarella cheese loaves and bricks may be stored under refrigerated conditions until subjected to subsequent shredding operations. The chilled cheese tends to toughen, making it even more difficult to shred into shred-like pieces or strands of substantially uniform size. Mozzarella cheese loaf has been heated to a molten condition in an extruder, and then discharged under compressive force through circular die holes of a die plate to form cheese strings, which are cooled in a brine solution. The cheese extrudates are cooled immediately upon extrusion before they deform, stick together, and/or otherwise lose the discrete elongated shape imparted by the extruder die. The conversion of the cheese to molten form and post-extrusion brine treatment increase process complexity and cost.
There also is a demand for low fat mozzarella cheeses in particular, which tend to have higher moisture content than the full fat counterpart products. At higher moisture content, some cheeses, such as mozzarella cheese, tend to become softer, making it even more difficult to shred the cheese using conventional shredding techniques.
There is a need for arrangements for forming cheese loaf, blocks or pieces directly into stable elongated shreds, and particularly chilled high moisture content cheese loaf, in an automated, non-manual manner without the need to heat process the cheese. As will become apparent from the descriptions that follow, the invention addresses these needs as well as providing other advantages and benefits.
The invention provides a method and system for forming shredded cheese directly from a quantity of cheese in an automated manner without the need to thermally process the cheese. In general, cheese shreds are formed from a quantity of cheese in which at least one discrete cheese piece is introduced into an elongated chamber which houses a conveyor operable to form homogenous cheese mass from the at least one cheese piece. Resulting cheese mass is transported forwardly and longitudinally of the chamber via the conveyor to a discharge outlet of the chamber. The cheese mass is pumped to a die plate under positive pressure. The cheese mass is extruded as continuous cheese extrudate strands at a temperature of less than about 50° F. through a plurality of elongated orifices of the die plate which receives the cheese mass after discharge from the chamber. The cheese extrudate strands are cut intermittently along their lengths to form discrete cheese shreds.
The cheese shred products obtained by the method and system of the present invention have cross-sectional shapes substantially corresponding to the shapes of the orifices in the die plate. Processing the cheese mass at temperatures less than about 50° F. improves the microbiological stability of the product. It also reduces and avoids heat distortions from occurring in the shred product shape. It additionally eliminates the need for rapid quenching of hot cheese extrudates. This inventive method and system avoids the need for process control over complex systems incorporating heating jackets or internal heating systems in the extruder, piping, pumps, dies, etc. This reduces process complexity, requirements and costs. The cheese shreds may be deposited directly on food products or in food packaging tray cells as part of a food product manufacturing line. For instance, this automated method and system eliminates the need to use intensive manual labor to place cheese shreds as toppings upon pizza products or in food packaging tray cells, or difficult to control conventional shred sprinkling systems like vibratory belts. Alternatively, they may be collected for packaging as a shredded cheese product per se.
In one particular embodiment, the cheese shreds may be deposited directly onto an intermediate food product, such as a dough-containing products like pizza, facilitating food production such as by minimizing processing losses and weight variability. The types of cheese which may be processed according to embodiments of this invention include natural cheeses, process cheeses, and cheese analogs or substitutes, or mixtures thereof. In one embodiment, the cheese is mozzarella or other pasta filata cheese, or other varieties of cheese, such as Emmental (Swiss), Cheddar, Gouda, Edam, etc. In one particular embodiment, cheese shreds are produced from refrigerated, high-moisture content cheese with the method and system of embodiments herein. In a more particular embodiment, the cheese being processed is high moisture-content pasta filata cheese, such as mozzarella loaves, bricks, etc., having at least about 52% moisture-content. The methods in accordance with embodiments of this invention make it feasible to extrude high-moisture content cheese at temperatures less than about 50° F. in strand-form.
In one embodiment, the high-moisture cheese may comprise refrigerated mozzarella cheese having a moisture content of at least about 52%, which is processed under unheated conditions in the inventive shredding system. In a particular embodiment, the cheese pieces are introduced into, processed within the extruder, and extruded in strand-form at the die plate, at a temperature less than about 45° F., more particularly, less than about 40° F. In one aspect, refrigerated cheese is fed into the extruder chamber, and the cheese mass formed therefrom in the extruder is conveyed to the die plate, while being maintained under refrigerated temperature conditions. In one aspect, the temperature of the cheese when extruded at the die plate is about 32° F. to about 45° F., particularly about 35° F. to about 45° F. In this manner, it is possible to directly convert refrigerated or otherwise chilled cheese pieces into shreds of approximately uniform dimensions without the need to heat the cheese to flowable or molten state to assist extrusion, which avoids the need to provide post-extrusion quench procedures to stabilize and avoid shape distortion from occurring in otherwise hot extruded shapes.
In another particular embodiment, a pump is used to force cheese through a single or multiple large diameter showerhead type dies with elongated orifices resembling the desired cross-sectional shape of a cheese shred. This pump includes a screw-type vacuum filler which receives the cheese in blocks of equal or different sizes and compresses the cheese into an airless homogenous flow without damaging the physical or flavor characteristics of the cheese. The cheese mass is extruded at a temperature of less than about 50° F. through the elongated die orifices after it exits the discharge outlet of the chamber, providing cheese extrudate strands. In one embodiment, a reciprocating multiwire cutter that translates rotationally relative to the die plate is used to cut the extrudate strands into shreds of desired length.
In a more particular embodiment, the die plate used in methods in accordance with embodiments herein includes a plurality of passageways extending from the above-indicated plurality of elongated orifices at a discharge side of the die plate to an inlet side thereof for receiving cheese mass discharged from the discharge outlet of the chamber. For purposes herein, “elongated” orifice shapes have a major diameter dimension which is at least 25%, preferably at least about 50%, larger in dimension than a minor diameter dimension oriented approximately 90 degrees thereto. In one embodiment, the passageways have substantially uniform cross-sectional shape corresponding with the elongated shape of the orifices. The orifices are non-circular and particularly are generally oval shaped or almond shaped. In one embodiment, the orifices have a major diameter/minor diameter ratio of about 2.25:1 to about 1.75:1. The orifices have a major dimension of about 6 mm to about 6.5 mm, and a minor dimension of about 3 mm to about 3.25 mm. In one embodiment, the die plate may have a thickness, which corresponds with the length of the passageways therein, of approximately 6 mm to approximately 13 mm.
In another particular embodiment, the cheese mass formed in the extruder is divided into multiple output streams with a water wheel, which feeds the output streams under pressure to respective die plates, which are operable for extruding continuous cheese extrudates through elongated orifices, which are cut into discrete shreds, at a plurality of food production lanes. The shreds may be deposited directly on a food product as a topping or in a food tray cell in each lane.
The figures are not necessarily drawn to scale. Similarly numbered elements in different figures represent like features unless indicated otherwise.
The present invention relates to a method and a system for producing cheese shreds from cheese extrudates. More specifically, this invention relates to extruding high moisture content mozzarella cheese at a temperature less than about 50° F. through a unique die comprising a die plate containing a plurality of orifices having elongated shapes, such as almond or oval shapes, etc., and the resulting cheese extrudate strands are intermittently cut along their lengths to provide discrete cheese shreds.
Referring to
The cheese pieces used as feed material to system 100 may be natural cheese (e.g., mozzarella, cheddar, Swiss, etc.), process cheese, soy cheese, imitation cheese, or combinations thereof. In one embodiment, the cheese pieces are natural cheese. In one embodiment, the cheese pieces are mozzarella cheese, particularly high moisture content mozzarella cheese. In a particular embodiment, the mozzarella cheese feed and shredded product obtained therefrom with the inventive system have a fat content (on dry basis) of less than about 30 percent, moisture of about 52 to about 60 percent, salt of about 1.6 to about 1.8 percent, and a pH of about 5.1 to about 5.3. The loose cheese pieces may be used in any geometric shape as long as the largest dimension of the shape is compatible with the feeding capacities of the hopper and the extruder. For example, in one embodiment, natural cheddar cheese may be precut from a large block or other source into cubes or other smaller regular shapes weighing about 4.5 kg (10 pounds) or less. For example, cubes having a size of about 5.1 cm to about 10.2 cm (about 2 to about 4 inches) may be used for introduction into an extruder system fed by a frustoconical shaped hopper having about a 10.2 cm (4 inch) diameter bottom opening (e.g., circular, square, etc.) and an intermeshing twin screw feed comprised of a pair of about 3.8 cm to about 5.1 cm (about 1.5 to about 2 inch) diameter intermeshed screws. Other cheese piece shapes also may be used alone or in combination with other geometries, such as cylinders, bars, shreds, and so forth.
The loose pieces of natural cheese or other dairy products are fed into extruder hopper by any suitable means. The loose cheese pieces can be mechanically or manually fed into the hopper at a controlled rate. For instance, a conveyor may be used to transfer the loose pieces to the hopper from an intake bin (not shown). After entering the hopper, the cheese pieces descend into an extruder unit including a low-shear screw feed. The low-shear screw feed particularly comprises an intermeshing twin screw feed operable at low speeds and fitted with minimal clearance relative to the inner surface of a generally cylindrical extruder chamber (barrel) that houses the twin screw mechanism. The screws either rotate in the same direction (co-current) or in opposite direction (counter-current) to each other. After entering the low-shear screw feed, the cheese pieces are mixed and folded together. The extruder is equipped with a vacuum pump which evacuates air from space within the extruder barrel where the screw feed is housed and the cheese mass therein. In one particular embodiment, the vacuum pump is combined with a screw extruder as an integral unit. Commercially available vacuum pumps include, for example, VEMAG robot model HP-15C, manufactured by Robert Reiser & Co., which are packaged as integrated units with a twin screw feed assembly for meat stuffing operations.
As the twin screw feed is working and conveying cheese mass forward towards the discharge outlet it keeps the product from being sucked into the vacuum pump area. The vacuum-assisted loading of the extruder de-aerates the cheese pieces introduced into the screw feed and the resulting mass, such that a substantially continuous homogeneous mass can be formed which is substantially free of air pockets. Air pockets in the cheese mass are undesirable as they did to burst upon exiting the extruder after being under compression within the die, forming noticeable structural defects in the extrudate. The removal of entrained air from the cheese mass also helps provide a hard, dense extrudate. The vacuum formed in the interior space of the screw housing by vacuum pump also helps draw cheese pieces from the hopper into the screw feed.
The cheese mass is conveyed as a viscous, substantially continuous, uninterrupted homogeneous mass by the twin screw feed out a discharge outlet 2020 of the extruder into piping 205 through which the cheese mass flows to water wheel 204 and before further processing including shred production. During passage of the extrudable cheese mixture through the extruder barrel, the twin screw conveyor feed mechanism acts on the cheese mass to convey it towards the discharge outlet in the form of two adjoining ropes of cheese material, which are compacted into a single continuous mass in piping 205 after discharge from outlet 2020. The pitch of the intermeshing flighting is relatively close but without causing contact between the two intermeshed screws. Also, clearance between the outermost peripheries and of the screws and the inside surface of the extruder barrel is minimized to help reduce shear forces that may be exerted on the cheese mass as it is conveyed by the twin screw assembly. For instance, while being driven in rotation at relatively low speed, e.g., approximately 40 to approximately 60 rpm, the intermeshing twin screw arrangement can still aggregate, mix and compact sufficient viscous cheese mass within the die to support continuous extrusion of the cheese mass, while reducing shear forces exerted on the cheese mass as it is conveyed to the discharge outlet under pressure. The extruder, including the vacuum pump, and integrally attached hopper may be positioned as a unitary unit on an upraised surface, such as a mobile cart, or alternatively positioned on a stationary surface such as a work floor, platform, countertop, etc.
As indicated, the cheese mass that exits the discharge outlet of the extruder is received in and pumped through piping or conduit 205 to a water wheel 204. The water wheel 204 divides the cheese mass flow discharged from the extruder via integral manifold means into a plurality of separate cheese mass substreams of approximately equal flow and pumps them to respective die assemblies 300 for shred production. The water wheel may be a commercially-available configuration, such as one manufactured by Robert Reiser & Co. The water wheel 204 operates using a series of vertical vane pumps in a cylindrical housing. The vane pumps are directly connected by metal shafts which ensure that each vane pump rotates at the same rate and delivers the same amount of material to its associated die and cutter set-up.
Referring to
Referring still to
In a particular embodiment, the cheese mass may be allowed to undergo a slight temperature increase during processing of several degrees (e.g., about 3° F. or less), but measures are taken to ensure that the cheese mass is kept at a chilled temperature through discharge from the die plate as extrudate strands. Among other benefits, this helps to improve and assure microbiological stability in the cheese product. In order to maintain the temperature of the cheese mass at a temperature below 50° F. during processing including in the extruder, water wheel, and at least until discharged from the die plate as shreddable strands, the system 100 may be set up in a refrigerated work space or room maintained at chilled temperature sufficient for that purpose. Alternatively or in addition thereto, the extruder, conduit, water wheel, and/or die plate may be equipped with cooling means, e.g., cooling jackets. Also, as previously indicated, a screw conveyor may be used that is driven in rotation at relatively low speed, which reduces shear forces exerted on the cheese mass as it is conveyed to the discharge outlet under pressure. The use of low shear conditions in the extruder has advantages. For example, occurrence of significant fat coalescence (e.g., fat globule formation), oiling (e.g., oil/solid mass phase separation), and/or protein aggregation is minimized, thereby improving product texture, homogeneity, and firmness.
Although
Referring to
The orifices 305 may comprise passageways having a constant cross-sectional shape through the thickness of the die plate. Alternatively, as illustrated in
For a die plate of approximately 15.2-20.3 cm (approx. 6-8 inch) diameter and an approximately 9.5 mm (⅜ inch) thickness, the plate may have approximately 100-140 orifices with the elongated shapes, such as almond-, oval-, elliptical-, or rectangular-shapes, and the like. The orifices are space-apart from one another and separated by land portions in the die plate. In one embodiment, the orifices have a major diameter/minor diameter ratio of about 2.25:1 to about 1.75:1. The orifices have a major dimension of about 6 mm to about 6.5 mm, and a minor dimension of about 3 mm to about 3.25 mm. In one embodiment, the die plate may have a thickness, which corresponds with the length of the passageways therein, approximately 6 mm (0.25 inch) to approximately 13 mm (0.5 inch).
Referring to
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After being discharged from die plate 303, the extrudate cheese strands typically are intermittently cut into discrete non-continuous shreds with any suitable means for that purpose. The cutting or slicing means may comprise a knife or other cutting device, such as a wire cutter knife, an air knife, a metal guillotine, rotary cutter, knock-off or a flicker wheel, and so forth. The motion of the cutting device and exit speed of the formable food product are two factors that regulate the length of the final shred product. The cutting device may include a mechanism for cutting the continuously extruded strands to desired lengths, depending on the food application. For example, the shred lengths formed may be about 1 to about 15 cm, although other lengths also can be provided. In some embodiments, the cutting device may have a reciprocating or circular motion. For instance, as illustrated in
Referring to
Pneumatic drive mechanism 920 includes a pneumatic cylinder 921 housed in a sleeve 922 which is bolted (923) to a bracket arm 940 that is integrally connected to the die head 931. The pneumatic cylinder 921 is hingably connected at one end (not shown) to clip member 924 that is fastened to a flanged portion 909 of rim portion 903 of cutting member 901. Pneumatic cylinder 921 is also fitted with a valve stem 922 through which needle valve control is made, such that pressurization causes cylinder 921 to stroke or translate laterally towards cutter part 901, which in turn causes a counter-clockwise rotation of cutting member 901, as indicated by the direction arrows in
Referring to
It will be appreciated that this invention is especially useful for directly converting chilled high-moisture cheeses, such as refrigerated mozzarella cheese having a moisture content of at least about 52%, into shredded form without needing to provide heated conditions in the inventive shredding system. In a particular embodiment, the cheese pieces are introduced into, processed within the extruder, and extruded in strand-form at the die plate, at a temperature less than about 45° F., more particularly, less than about 40° F. In one aspect, refrigerated cheese is fed into the extruder chamber, and the cheese mass formed therefrom in the extruder is conveyed to the die plate, while being maintained under refrigerated temperature conditions. In one aspect, the temperature of the cheese when extruded at the die plate is about 32° F. to about 45° F., particularly about 35° F. to about 45° F. In this manner, it is possible to directly convert refrigerated or otherwise chilled cheese pieces into shreds of approximately uniform dimensions without the need to heat the cheese to flowable or molten state to assist extrusion, which further avoids the need to provide post-extrusion quench procedures to stabilize and avoid shape distortion from occurring in otherwise hot extruded shapes. This inventive method and system avoids the need for process control over complex systems incorporating heating jackets or internal heating systems in the extruder, piping, pumps, dies, etc. This reduces process complexity, requirements and costs.
Also, although use of ingredients in addition to the cheese pieces are not categorically excluded from the method, no processing aids or product modifiers, e.g., water, salt, plasticizers, emulsifiers, etc., need be included with the cheese pieces fed into the process system described herein to provide high quality cheese shred product. For instance, raw natural or process cheese material by itself can be processed in the shredding system without the need for co-ingredients. Additional edible ingredients, such as meat pieces, vegetable pieces, herbs, spices, vitamins, calcium or other minerals may be optionally added to the cheese mass via the hopper to the extent they are dispersible in the cheese mass and do not obstruct or blind the orifices on the die plate.
The Examples that follow are intended to illustrate, and not limit, the invention. All percentages described herein are by weight, unless indicated otherwise.
Leprino brand mozzarella cheese (53% moisture) with starch was cut into 15.2 cm (6 inch)×7.6 cm (3 inch) pieces weighing approximately 0.5 lbs. The cheese temperature at the time of use was about 35° F. and was still about 35° F. after extrusion.
A customized die plate was fitted to an extrusion system, as described below. The die plate was molded rigid plastic construction having an 18 cm (7 inch) diameter and 0.95 cm (⅜ inch) in thickness. The plate had 117 orifices formed in it having almond-shapes, similar to that illustrated in
A VEMAG ROBOT model HP-15C vacuum pump/extruder, manufactured by Robert Reiser & Co. was set-up to operate with the following settings: Weight=0068 000, Pause=0050, Twist=1500, Speed=0, P1=0. The pressure in the system was between about 300 and about 350 psi. Approximately 80 pounds of the cheese pieces were dumped into the extruder hopper. The screws were operated at about 75 rpm to mix, knead, and compact the cheese pieces into a homogenous cheese mass before exiting the discharge outlet of the extruder. The throughput rate was about 8 lb/min. The cheese mass exiting the vacuum pump/extruder unit was conducted to a Reiser 6-inch water wheel, which divided the cheese mass into separate equal streams collected in respective vane pumps. The water wheel supported die plates mounted on two separate deposition lanes. The divided cheese streams were each pumped from the water wheel to a die plate, described above, and extruded as continuous strands, i.e., the cheese extrudate. The extrudate product was extruded at 35° F. using the die. A wire cutter was used to cut the continuous strands into discrete cheese shreds having lengths of about 3 cm to about 4 cm. The cheese shreds had cross-sectional shapes along their lengths that substantially corresponded to the die plate orifice shapes.
While the invention has been particularly described with specific reference to particular process and product embodiments, it will be appreciated that various alterations, modifications and adaptations may be based on the present disclosure, and are intended to be within the spirit and scope of the present invention as defined by the following claims.
