Patent Application
20060040027
The invention generally relates to a process for providing edible granules from cheese, and, particularly, the invention relates to providing granules from cheese in a single-unit operation.
Cheese is generally manufactured in relatively large blocks and cut for sale into smaller blocks or chunks of shapes and sizes selected according to consumer or customer preference. The cutting operation leaves a quantity of irregular pieces of cheese. An ongoing goal in the cheese industry is to find commercial uses for such pieces.
Cheese powders have been used in a variety of foods, including smooth sauces, snack seasonings, and free-flowing fillings. For example, consumers are familiar with shelf-stable cheese sauce powders for macaroni and cheese dinners, which can be reconstituted with milk and/or other ingredients. Grated or powdered cheeses have been manufactured by spray drying processes used on pumpable forms of cheese in accordance with well-known practices. They also have been manufactured by dehydrating cheese curd in a drum drier, and then disintegrating the dehydrated curd in a milling device. Also, grated cheeses have been made by cutting chunks or pieces of hard cheese into fine particles, and then dehydrating the fine particles. Cheese granules also have been manufactured from cheese pieces which are shredded, freeze dried, and ground in a multi-step procedure. These procedures generally entail conducting multiple unit operations performed in separate pieces of equipment.
Arrangements are needed for manufacturing shelf-stable grated cheese products with fewer process steps and equipment requirements. The invention addresses the above and other needs in an efficient and economically feasible manner.
This invention provides a process grinding cheese into grated form in a single unit operation. This process preferably combines and executes this operation in a short duration operation that substantially preserves desirable functional attributes and flavor of the cheese.
In one embodiment, wet cheese material is grated in a combined heat treatment and grinding process in which compressed heated air and wet cheese material are separately introduced into an enclosure that includes a truncated conical shaped section. After introduction, the compressed heated air travels generally along a downward path through the enclosure until it reaches a lower end thereof. The air flows back up from the lower end of the enclosure in a central region thereof until exiting the enclosure via an exhaust duct. The wet cheese material is separately introduced into an upper end of the enclosure, and the cheese material becomes entrained in the heated air traveling downward through the enclosure until reaching the lower end of the enclosure.
During this movement of the cheese material from the upper end of the enclosure down to the lower end thereof, the cheese material is thermally and physically processed in mutually beneficial ways. The cheese material is dehydrated by the heated air in which it is suspended in a dynamic air flow system. During the same unit operation, the cheese material is disintegrated into small particles in an extremely short period of time. The outcome is that significant amounts of the introduced wet cheese material are dried and ground before reaching a lower end of the enclosure. No moving mechanical parts are needed for effecting grinding of the wet cheese material.
Consequently, in these embodiments, a solid particulate product including dried and ground cheese material is discharged and recovered from the lower end of the enclosure, while air and moisture vapor released from the cheese material from drying is exhausted from the system via the exhaust duct. In one particular embodiment, the enclosure is a two-part structure including an upper cylindrical shaped enclosure in which the compressed heated air and wet cheese material are separately introduced, and the cylindrical enclosure adjoins and fluidly communicates with a lower enclosure having the truncated conical shape that includes the lower end of the overall structure from which the dried and ground cheese material is dispensed.
The single-stage process for drying and grinding of wet cheese material in a continuous manner in a single unit operation according to the preferred embodiments of this invention offers numerous advantages over conventional schemes for drying and granulating wet cheese material. The single-stage treatment makes it possible to produce a grated cheese material from wet cheese material at a relatively low temperature, in a short duration procedure. Drying and grinding processes are both achieved in a single-stage operation without impairing the desirable functional and flavor attributes of the cheese material, and without requiring different processes be performed in different equipment. Additionally, the process can be operated in a continuous mode as the compressed heated air is continuously exhausted from the system after entraining the cheese material downward through the enclosure to its lower end, and ground cheese material can be withdrawn from the lower end of the enclosure in an air-tight manner, such as by using a rotary air-lock. Relatively little if any cheese material residue is left on the inner walls of the processing unit, making it easy to clean and facilitating switching to a different type of cheese material for processing within the unit. These advantages reduce process complexity, production time, and production and service costs.
The grated cheese product obtained may be used, for example, as an edible functional ingredient for food manufacture, such as process cheese manufacture. The dehydration of the cheese that can be imparted during the grinding operation by using heated air can increase stability and preservability of the granular cheese product. Among other benefits, the partly dehydrated cheese product is more resistant to mold growth. The act of drying and grating brings the product to a more shelf-stable, storable ingredient form with numerous possible applications such as in cheese powders, process cheese, sauces, and so forth. For instance, it may be used as a shelf-stable food ingredient, such as a dry cheese mix ingredient, which may be reconstituted with water, or as a food additive or flavoring material.
Other features and advantages of the invention will become apparent from the following detailed description of preferred embodiments of the invention with reference to the drawings, in which:
The features depicted in the figures are not necessarily drawn to scale. Similarly numbered elements in different figures represent similar components unless indicated otherwise.
The present invention relates to a process for grinding cheese materials into grated form, and, in one embodiment, to a process for dehydrating and grinding high-moisture content or “wet” cheese during the same unit operation. The term “grated” means that small granules of the cheese are produced. The term “grated” does not mean that shreds of cheese are produced. “Shredded” cheese refers to elongated cheese pieces in the shapes of strings, strips, or cylinders, and the like. The invention will be described below with specific reference to unique single-stage processing of cheese materials. For purposes herein, the term “wet” as used to characterize a cheese or similar dairy product material refers to a material containing at least 14 wt. % total water content, in liquid, frozen and/or vapor form. The present invention also may be applied to grind lower-moisture content cheese materials.
In an embodiment, wet cheese material is subjected to drying and grinding into a small particle size within a short period of time in a single-stage process performed in one unit operation. The single-stage process is implemented on a cyclonic type system that may be operated in a manner whereby the wet cheese material may be thermally and physically acted upon at the same time within the same processing unit in a beneficial manner. A dried and ground cheese material is obtained in a flowable grated form (e.g., a solid fine particulate).
For purposes herein, “drying” means dehydrating, i.e., reducing moisture content; and “grinding” a particle means crushing, pulverizing, abrading, wearing, or rubbing the particle to break it down into smaller particles and/or liberate smaller particles, and includes mechanisms involving contact between moving particles, and/or between a moving particle and a static surface.
Referring to
In step 2, a grated cheese material product is obtained which is suitable for use in comestibles. The grated cheese material obtained substantially retains its flavor and functional attributes through the single-stage treatment. The grated cheese product may be stably stored until used or re-used in food preparation or food production. The grated cheese product may be used as an ingredient in cheese production in which its flavor or functional attributes may be desirable or useful.
Referring now to
Referring to
Compressed heated air 116 and wet cheese material 102 are separately introduced into the cyclone 101 at the upper enclosure 103. The processed wet cheese material is discharged as a solid particulate 113 from the lower end 112 of the cyclone 101. A valve mechanism 111, such as a rotary valve or rotary air-lock, is shown that permits extraction of dried, ground cheese material from the cyclone without interrupting continuous operation of the system and which minimizes leakage of the heated air from the cyclone 101. If the cyclone 101 is operated without an air-lock or the like at the bottom discharge end of the cyclone 101, the system may run less efficiently as heated air will be forced out of the lower end 112, which may need to be compensated for in the air feed rate. Air, and moisture vapor released from the cheese material during heat treatment within the cyclone 101, is exhausted as exhaust gases 114 from the cyclone via sleeve 107 and exhaust duct 109. Some nominal amount of chaff may be liberated from the cheese material during their processing in the cyclone and gets eliminated with the exhaust gas stream 114. The exhaust gas stream 114 optionally may be particle filtered, and/or scrubbed to strip out sulfur-containing compounds or other compounds, such as using a separate scrubber module (not shown), e.g. a packed bed type scrubber, before it is vented to the atmosphere. Sieving device 115 is optional, and is described in more detail later herein. Generally, it can be used to redirect oversize or coarser product in particulate product 113 which may be re-introduced into the cyclone 101 for additional treatment by itself or in combination with fresh feedstock that has not yet been treated therein.
To introduce the compressed heated air 116 into cyclone 101, an air pressurizing mechanism 121, such as a blower or air compressor, generates a high volume, high velocity compressed air stream that is conducted via hot air ducting 125 through an air heater 123, and from there is introduced into upper enclosure 103 of cyclone 101. For purposes herein, the term “heated air” refers to air heated to a temperature above ambient temperature, e.g., above 75° F. (24° C.). The term “compressed air” refers to air compressed to a pressure above atmospheric pressure, e.g., above 14.7 psia (lb./inch2 absolute). The term “compressed heat air” refers to air having both these characteristics. The compressed heated air 116 is introduced into chamber 104 substantially tangentially to an inner wall 108 of the upper enclosure 103. This can be done, for example, by directing the heated air stream 116 to a plurality of holes 120 (e.g., 2 to 8 holes) circumferentially spaced around and provided through the wall 108 of the upper enclosure 103 through which the heated air stream is introduced. Deflection plates 122 can be mounted on inner wall 108 of upper enclosure 103 for deflecting the incoming stream of heated air into a direction substantially tangential to the inner wall 108 according to an arrangement that has been described, for example, in U.S. patent application publication No. 2002/0027173 A1, which descriptions are incorporated herein by reference. The heated air may be introduced into the upper enclosure 103 of cyclone 101 in a counter-clockwise or a clockwise direction.
The introduced air 10 generally may be further pressurized cyclonically in the chamber 104 and cavity 106. Due to the centrifugal forces present in the cyclonic environment, it is thought that the pressure nearer the outer extremities of the cavity 106 is substantially greater than atmospheric pressure, while the pressure nearer the central axis of the cavity 106 is less than atmospheric pressure. As shown in
A vortex breaking means (not shown) optionally can be interposed below or inside the lower end 112 to encourage the transition of the larger vortex 13 to the smaller vortex 15. Various vortex breaking arrangements for cyclones are known, such as the introduction of a box-shaped enclosure at the bottom of the conical enclosure.
The wet cheese material 102 is separately introduced into upper enclosure 103. The introduced wet cheese material drops gravitationally downward into chamber 104 until they become entrained in the heated air vortex 13 within cyclone 101. Preferably, the wet cheese material is introduced into upper enclosure 103 in an orientation such that they will fall into the cyclonic vortex 13 generated within cyclone 101, where located in the space between the sleeve 107, and inner wall 108 of the upper enclosure 103. This feed technique serves to minimize the amount of wet cheese material that may initially fall into extreme inner or outer radial portions of the vortex where the cyclonic forces that the cheese material experiences may be lower.
The entrained cheese material travels in the vortex 13 of heated air that spirals or otherwise travels downward through the lower enclosure 105 until reaching the lower end 112 of the lower enclosure 105. During this downward flow path, the cheese material is dehydrated by the heated air in which they are suspended in such a dynamic air-flow system. They also are ground during the downward flow path. The various dehydration and grinding effects on the cheese material may occur at different respective times, and/or several of the effects may occur simultaneously at a particular point or points in time, during the downward flow path of the cheese material through the cyclone. While not desiring to be bound to any theory, it is thought that the possible pressure-gradient and coriolis forces across, cavitation explosions, and the collision interaction between the cheese material particles entrained in the high-velocity cyclonically pressurized may be violently disruptive to the physical structure of that cheese material. Alternatively, or in addition thereto, the centrifugal force of the vortex may move the cheese material forcefully against inner walls 108 and 123 of the enclosure. These modes of attrition, individually or in combination, or other modes of attrition that may occur within the cyclone which may not be fully understood, bring about comminuting (grinding) of the cheese material concurrent with drying it. As a result, during this movement of the cheese material from the upper enclosure 103 down to the lower end 112 of the lower enclosure 105, the cheese material is thermally and physically processed in beneficial ways. The unit 101 requires no moving mechanical parts for effecting grinding of the wet cheese material.
In a further embodiment of the invention, the discharged solid particulate product 113 can be screened, such as using a sieve, such as a screen sieve or other suitable particulate separation/classifying mechanism 115, to sort and separate the finer fraction of ground cheese material 1130 in the solid particulate product 113 that have particle sizes meeting a size criterion, such as being less than a predetermined size, which are suitable for post-grinding processing, from the coarser product fraction 1131. The coarser (oversize) product fraction 1131 can be redirected into the upper enclosure of the cyclone for additional processing therein. A conveyor (not shown) could be used to mechanically transport the coarser material back to feed introducing means 127 or other introduction means in upper enclosure 103 of cyclone 101. Also, feed introducing means 127 may be an inclined conveyor (not shown), which transports cheese feed from a lower location up to and into chamber 104 of the cyclone 101 at the upper enclosure 103.
It will be appreciated that sleeve 107 can be controllably moved up and down to different vertical positions within cyclone 101. In general, the lower sleeve 107 is spaced relative to the cavity 106, the smaller the combined total volume of the cyclone 101 which is available for air circulation. Since the volume of air being introduced remains constant, this reduction in volume causes a faster flow of air, causing greater cyclonic effect throughout cavity 106 and consequently causing the cheese material to be ground to circulate longer in the chamber 104 and the cavity 106. Raising the sleeve 107 generally has the opposite effect. For a given feed and operating conditions, the vertical position of sleeve 107 can be adjusted to improve process efficiency and yield.
Also, a damper 126 can be provided on exhaust duct 109 to control the volume of air permitted to escape from the central, low-pressure region of cavity 106 into the ambient atmosphere, which can affect the cyclonic velocities and force gradients within cyclone 101.
By continually feeding cheese material into cyclone 101, a continuous throughput of dried and ground cheese material 113 is obtained. A non-limiting example of a commercial apparatus that can be operated in a continuous manner while processing cheese material according to processes of this invention is a WINDHEXE apparatus, manufactured by Vortex Dehydration Systems, LLC, Hanover Md., U.S.A. Descriptions of that type of apparatus are set forth in U.S. patent application publication No. 2002/0027173 A1, which descriptions are incorporated in their entirety herein by reference.
The cyclonic system 100 provides very high heat transfer rates from hot air to cheese material for drying, and mechanical energy to crack and granulate cheese material as it descends through the conical section of the dryer. The cheese material exiting the cyclone 101 exhibits a flowable solid particulate type form, which may be a flour or powder like material. The one-stage process offers numerous advantages over conventional schemes used for powdering or grating wet cheese material using separate drying and grinding processes and equipment.
In one process scheme for processing wet cheese material, the introduction of the heated air into the cyclone comprises supplying compressed heated air at an inlet pressure within the range of from about 10 psig to about 100 psig, particularly from about 15 psig to about 60 psig. The heated air generally is introduced into the cyclone at a temperature within the range of about 120° F. to about 900° F., particularly about 300° F. to about 500° F., more particularly about 325° F. to about 400° F. In one aspect, the inlet air temperature does not exceed 250° F. The volumetric introduction rate of the heated air into the cyclone is within the range of from about 500 cubic feet per minute to about 10,000 cubic feet per minute, particularly from about 1,500 cubic feet per minute to about 3,000 cubic feet per minute. The feed rate of the wet cheese material can vary, but generally may be in the range of about 1 to about 300 pounds per minute, particularly about 50 to about 150 pounds per minute, for about a 1 to about a 10 foot diameter (maximum) cyclone. The cyclone diameter may be, for example, from about 1 to about 10 feet diameter, particularly about 1 to about 6 feet in diameter.
The wet cheese material may be processed within the above-noted cyclone arrangement within a very short period of time. In one embodiment, upon introducing the wet cheese material into the cyclone, a dried and grated product thereof is discharged from the processing unit within about 15 seconds, and particularly within about 1 to about 5 seconds. After exiting the cyclone unit, any volatile components in the exhaust also optionally may be handled by conducting the cyclone exhaust through a scrubber unit and the like (not shown).
Substantially all the introduced wet cheese material may be discharged as processed product within such a short period of time. The above-noted processing temperatures and durations applied during drying and grinding of the wet cheese material generally are low enough to help prevent any significant undesired changes in the protein structure, or other physico-chemical attributes relevant to food-processing, from occurring during the single-stage drying and grinding treatment such as described herein. The protein content is preserved substantially intact through the drying and grinding of the wet cheese material.
Generally, the cheese material used as the feed material contains about 6 wt % to about 99 wt. % moisture (i.e., water in liquid, frozen and/or vapor form). In one embodiment, the cheese material used as the feed material of a single-stage grinding process generally contains at least about 14 wt. % moisture, particularly about 14 wt. % to about 99 wt. %, and more particularly about 14 wt. % to about 65 wt. % moisture, when introduced into the cyclone 101 of system 100. The cheese material that can be used as the feed material can be derived from commercial cheese manufacture or other sources of cheese material. The ground (grated) cheese material obtained from the process generally contains about 1 wt. % to about 40 wt. % moisture, particularly about 1 to about 25 wt. %, and more particularly about 1 wt. % to about 13 wt. %.
Ground cheese material obtained by a single-stage drying and grinding process preferably has commercially useful particle sizes. In one embodiment, the dried, ground (grated) cheese product obtained by processing high-moisture or low-moisture content cheese material according to an embodiment of this invention may have an average particle size ranging from about 1 to about 1,000 microns, particularly about 2 to about 1,000 microns, particularly about 10 to about 400 microns, and even more particularly about 2 to about 50 microns. In one embodiment, the solid particulate product obtained as the bottoms of the cyclone comprise at least about 50% ground cheese material having an average particle size of about 1 micron to about 1,000 microns.
The grated cheese obtained for processing may be derived, for example, from natural or process cheeses. Natural cheeses include ripened natural cheese and unripened natural cheese. “Natural” cheese is made directly from milk by coagulating or curdling milk, stirring and heating the curd, draining off the whey, and collecting or pressing the curd. Desirable flavor and texture are obtained in many cheeses by curing the cheese, that is, holding it for a specified time, at a specified temperature and humidity. This basic method is used to produce a very large number of different types of cheese by altering time, temperature, pH, curd handling and other variables.
“Process cheese” generally refers to any of various types of natural cheese and mixing such ground cheese with added emulsifier and heating until a uniform plastic cheese mass is obtained. The process cheeses include pasteurized process cheeses.
The cheese material which may be subjected to processing is not particularly limited. It may be, for example, process cheese such as American process cheese; very hard cheese such as Parmesan, Romano, Sapsago, Spalen, Asiago; Hard cheese such as Cheddar, Caciocavallo, Swiss, Colby, Edam, Gouda, Emmentaler, Gruyere, granular-curd, stirred-curd; Semisoft cheese such as Monterey Jack, brick, mozzarella, Blue, feta, Havarti, Muenster, provolone, Roquefort, Gorgonzola, Stilton, Wensley-dale; Soft cheese such as Brie, Camembert, Neufchatel, Ricotta, cottage, cream cheese, and mixtures thereof.
In one preferred embodiment, the single unit process is useful to transform fragments, chunks and/or relatively large pieces of hard or very hard cheeses having high-moisture content into a dry flowable powder form in a single stage operation. In one embodiment, the cheese pieces fed into the cyclonic processor for conversion into granular form have a moisture content of at least about 14 wt. % or more.
The grated cheese product obtained is suitable, for example, for use as an edible, functional ingredient in food manufacture, such as process cheese production. In one embodiment, the grated cheese material is used as a unique functional ingredient in lieu of part or all of typically used cheese or substitute cheese ingredients suitable for process cheese making. For example, in the manufacture of process cheese, the grated cheese product may be used as part or all of the cheese source used in preparing a cheese blend. For example the grated cheese, alone or in combination with other type of cheese sources, may be blended with an emulsifier in an aqueous environment and heated to form a homogenous molten mass that can be shaped, cooled, and cut into desired sizes.
The grated cheese product also may be used as a shelf-stable food ingredient, such as a dry cheese mix ingredient which may be reconstituted with water. It also may be used as a shelf-stable flavoring material or food additive.
The weights of the chunks or pieces of cheese that may dried and substantially completely ground into a powder form in a single unit operation is relatively broad. In one embodiment, the cheese material used as feed comprises discrete, self-supporting pieces of cheese having an average weight of about 1 g or more, and particularly about 5 g to about 40 g.
In another embodiment, cheese materials having a moisture content more than 14 wt. % may be processed in the cyclone using compressed ambient air or otherwise unheated air, although the granular cheese product discharged from the cyclone may need to be further dehydrated as part of a separate additional process step to ensure adequate shelf-stability is provided. In general, it is preferred to provide a moisture content in the granular cheese product which is less than about 25 wt. %, and preferably less than about 14 wt. % to further ensure that a shelf-stable product is attained. The invention also is applicable to cheese materials having a moisture content less than 14 wt. %, where cheese grinding generally will be the predominant process treatment, although some dehydration also may be induced as well. If the cheese starting material contains less than about 14 wt. % moisture, if may be possible to operate the cyclonic processor at a reduced heated air temperature or without the need to heat the compressed air to an elevated temperature before its introduction into the cyclone. If unheated air or only mildly heated air is used (e.g., an air temperature of less than about 120° F.), it may be desirable to dehumidify the compressed air before it is introduced into the cyclone unit in high relative humidity (RH) conditions (e.g., RH greater than about 70%) to ensure that the cheese material can be attrited into granular form and does not become sticky or pasty inside the cyclone during processing. The air may be dehumidified using a conventional cooling coil unit or similar device used for dehumidification of process air.
The grated cheese material obtained by the single-stage process treatment is edible and may be used in a wide variety of foodstuffs for a variety of purposes. The grated cheese material retains the essential cheese flavoring attributes and does not have an unpleasant taste or odor. The grated cheese material has ability to contribute flavor and function without adversely impacting food products into which it may be incorporated. The grated cheese material obtained generally is shelf stable, and may be used to impart flavor and/or functional properties to a cheese material being manufactured after many months of storage of the grated cheese material, such as up to about twelve months storage/shelf life or more.
The single-stage processing unit is left relatively clean and tidy because the cheese material does not tend to leave residues on the inner surfaces of the process unit. This clean and tidy operation can facilitate any desired change-over for processing a different type of feed material within the same unit. For instance, the type of wet cheese material run through the system may be changed without the need to clean the system interior of residues of a prior treatment conducted therein on a different type of food material.
The Examples that follow are intended to illustrate, and not limit, the invention. All percentages are by weight, unless indicated otherwise.
Kraft® Natural Shredded Cheese (36 wt. % moisture), a commercially available product, was fed into a WINDHEXE apparatus for circular vortex air-flow material grinding. The WINDHEXE apparatus was manufactured by Vortex Dehydration Systems, LLC, Hanover, Md., U.S.A. The basic configuration of that type of apparatus is described in U.S. patent application publication No. 2002/0027173 A1, and reference is made thereto. The process unit had four inlet ports equidistantly spaced around the upper portion of the apparatus through which the compressed air stream was concurrently introduced in a counter-clockwise direction.
A two-foot diameter WINDHEXE apparatus was tested. The diameter size refers to the chamber size of the enclosure into which air and dual-density cheese material introductions were made. The conditions of this experiment are described below. The feed rate of the cookies was set for an approximate discharge of 3 pounds solid product per minute, and approximately 20 pounds of cheese material was tested in the apparatus. The cheese material was loaded into a hopper that directly fed onto a three-inch belt conveyor that fed into the WINDHEXE apparatus. Testing was performed in the two-foot diameter WINDHEXE apparatus with unheated compressed air introduced at 65-75° F., an air introduction rate of 2,500 cubic feet per minute (cfm) and pressure of 40-50 psig.
A cheese material exiting the apparatus included grated cheese in finely ground form. This grated cheese material was discharged from the bottom of the cyclone in about two seconds after the cheese had been introduced into the processing unit. The grated cheese obtained had an average particle size of about 5 to about 50 microns, and a moisture content of about 35%. The reclaimed cheese was flavorful, and retained flavor well through the treatment. It was functionally suitable for use as a food ingredient in cheese production. Additional studies have shown that feed rate and air temperature variation may be used to control the base cake granulation and moisture content.
The experiment of Example 1 was repeated except that aged Parmesan cheese in shredded form was used instead as the feed cheese. The Parmesan cheese had an initial moisture content of about 30%. The aged Parmesan cheese was commercially available Parmesan cheese manufactured by Kraft Foods Holdings Inc. (Tulare, Calif.). Upon processing the Parmesan cheese shreds in the cyclone unit, a dry-grated product was rapidly obtained within a few seconds after being fed into the unit having a moisture level of 21-24%. The cheese product was flavorful, shelf stable, and retained flavor well through the treatment. It was functionally suitable for use as a food ingredient in cheese production.
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.
