Method and apparatus for manufacturing frozen products

Abstract

The invention relates to a method for manufacturing frozen products, in which a predetermined amount of carbon dioxide snow is manufactured and is piled to form a volume of snow. Subsequently, a mould cavity is pressed into the surface of the volume of snow, thereby forming a recess, into which at least one product to be cooled is filled. In a cooling device, the product in the volume of snow is thoroughly cooled, while the volume of snow itself gradually sublimates. The process and device are particularly suitable for the manufacture of IQF products.

Description

[0001] The present invention relates to a method and apparatus for manufacturing frozen products, particularly for manufacturing so-called IQF (individual quick-frozen) products.

[0002] To ensure high product quality, in many cases, temperature-sensitive products, especially food, pharmaceutical products, or biological or medical samples, must be cooled very rapidly to storage temperature after manufacturing. This presents a significant challenge, particularly with the IQF method, where products must be cooled very quickly, either individually or in predetermined batches, without freezing together or being over- or under-cooled.

[0003] One possible approach for rapidly cooling individual products is to place them individually on a conveyor belt or frame and then thoroughly freeze them in a cooling tunnel or freezer. However, this becomes economically impractical, especially when cooling large quantities of relatively small products.

[0004] Another possible approach is to use an immersion frosting unit, in which the products to be cooled are introduced into a liquid nitrogen bath independently of each other. However, this type of system has the disadvantage of using a large amount of refrigerant, and the large temperature gradient during the cooling process may lead to quality loss in sensitive products.

[0005] Furthermore, it is known to introduce the product into a mold or compartment constructed such that each portion forms independently, and then freeze it. This method can also be used if the initial liquid or molten product is to be frozen in multiple portions. However, additional costs are required to remove the frozen product from the mold or compartment and to prepare and clean the mold or compartment.

[0006] WO 2010 / 104526 A1, EP 2 594 870 A1, and EP 3 333 521 A1 disclose cooling tunnels equipped with mechanical devices (such as camshafts or vibrating screens) that move the product during the freezing process, thereby preventing the products from freezing together. However, this type of system cannot be used if the initial liquid product is to be cooled in multiple portions. Furthermore, it is not always necessary to prevent products from freezing together.

[0007] Therefore, the object of the present invention is to provide a method and apparatus for rapidly cooling products, particularly for manufacturing IQF products, which overcomes the disadvantages of the prior art and is particularly suitable for manufacturing frozen portions of liquid initial products.

[0008] This objective is achieved by the method and apparatus according to the invention. Advantageous modifications of the invention are specified in the dependent claims.

[0009] Therefore, the method according to the present invention is characterized in that, - Produce a predetermined amount of carbon dioxide snow and accumulate it to form a certain volume of snow. - Press the mold cavity into the surface of a certain volume of snow, thereby forming at least one recess in the certain volume of snow. - Place at least one product to be cooled in the at least one recess, and - A certain volume of snow, containing at least one product, is supplied to a cooling device, where the product is thoroughly cooled.

[0010] According to the invention, a predetermined amount of carbon dioxide snow is therefore first produced. This is, for example, by expanding pressurized liquid carbon dioxide at an expansion nozzle to produce a mixture of carbon dioxide snow and carbon dioxide gas, followed by the accumulation of the carbon dioxide snow to form a certain volume of snow. Here, the certain volume of snow can be produced directly in place, for example by means of a snow-feeding funnel arranged above a working area to which a certain volume of snow is supplied; in this case, the produced carbon dioxide snow falls directly into the working area. Alternatively, the snow is first produced in a separate device and then supplied to the working area via a conveyor section of longer or shorter length. The working area to which a certain volume of snow is supplied is formed in a fixed position, wherein at least the device for forming a mold cavity and the device for placing the product are successively supplied to the working area; or the working area is formed in a movable manner, for example, formed on a conveyor belt, and successively supplied to the fixedly positioned device for forming the mold cavity, the device for placing the product, and the cooling device. In addition, there may be devices that help form a certain volume of snow in the working area, and especially during the accumulation of carbon dioxide snow, form the lateral boundary of the produced volume of snow, such as fixed or movable lateral wall elements or profile elements on a conveyor belt.

[0011] Subsequently, a mold cavity is pressed into the surface of a certain volume of snow using a press. For this purpose, the press is equipped with a die having at least one protruding profile that leaves at least one recess in the snow during pressing. The product is then placed in one or more recesses. The product is rapidly frozen on its surface by contact with carbon dioxide snow at approximately -79°C. In the case of multiple recesses, the carbon dioxide snow present between the recesses effectively prevents the products from freezing together. Simultaneously, the snow volume is compressed as a whole through pressing, thus becoming stable for further processing, particularly for further transport to a cooling device.

[0012] In the cooling apparatus, an atmosphere is preferably maintained at a temperature equal to or slightly above the sublimation temperature of carbon dioxide, so that a certain volume of snow gradually sublimates during the cooling process, leaving behind a frozen product now present as separate individual components, which can then be packaged or supplied for further processing. For this purpose, it is also recommended to use liquid carbon dioxide to operate the cooling apparatus, for which the liquid carbon dioxide can be drawn from the same source used to produce the certain volume of snow. However, the invention does not preclude the removal of carbon dioxide snow only in subsequent process steps; in this case, the temperature in the cooling apparatus may also be below the sublimation temperature of carbon dioxide.

[0013] The product can be a block product, such as fruit or vegetables; or it can be a product that is liquid or paste when it is placed in the mold cavity and is poured into the recess of the mold cavity, thus being divided into multiple portions, such as a sauce, juice or a pre-melted (e.g., fat-containing) product.

[0014] The apparatus for manufacturing frozen products according to the invention comprises at least the following components (hereinafter also referred to as "stations"): a means for providing a volume of snow; a press equipped with a die having at least one protruding profile and intended for pressing a die cavity into the surface of a volume of snow, thereby forming at least one recess; a metering device for feeding at least one product into the at least one recess; and a cooling device for finally and thoroughly cooling the product.

[0015] The apparatus for providing a given volume of snow preferably includes means for producing a predetermined amount of carbon dioxide snow, in which carbon dioxide snow is produced by expanding liquid carbon dioxide introduced under pressure. For example, this involves a snow delivery horn arranged above a work area defined as providing a given volume of snow, so that the carbon dioxide snow produced in the snow delivery horn falls onto the work area under gravity and forms a given volume of snow. The snow delivery horn is attached to a liquid carbon dioxide supply line including a valve by means of which the amount of carbon dioxide supplied to the snow delivery horn can be controlled.

[0016] In a particularly preferred alternative improvement, a volume of snow is produced in a separate device and then supplied to a work area where a volume of snow is provided. For example, a device for metering carbon dioxide snow, as described in more detail in EP 3 222 946 A1 or EP 3 433552 A1, can be used. In these cases, liquid carbon dioxide introduced via a supply line expands, causing continuous production of carbon dioxide snow in a storage container temporarily storing it. The storage container is equipped with a discharge unit by means of which a defined amount of carbon dioxide snow is separated from a defined amount of snow accumulated in the storage container at defined time intervals; ejected from a side opening or bottom opening in the storage container; and conveyed to or falling onto the work area, for example by means of a chute or conveyor belt, where it forms a defined volume of snow. The carbon dioxide gas generated during the expansion of the liquid carbon dioxide is also separated from the carbon dioxide snow in the storage container, i.e., before the carbon dioxide snow is supplied to the work area. Therefore, firstly, the accumulation of a defined volume of snow in the work area is avoided due to possible turbulent airflow interference, and secondly, the safe removal of carbon dioxide gas is ensured. This type of arrangement allows for the continuous delivery of multiple volumes of snow at a rapid cycle frequency.

[0017] To facilitate the accumulation of carbon dioxide snow, a vessel in which carbon dioxide snow is introduced can be positioned in the work area. The term "vessel" should be understood in a very general sense and is intended to refer only to any device in which a volume of snow can be placed, even if it is only temporarily present. For example, it can be a container closed at the bottom and its sidewalls. However, it is also conceivable to provide devices for lateral and / or bottom-side definition of a volume of snow, such as movable or flexible boundary elements, only during the production of a volume of snow. In particular, such devices can also be implemented by components of a conveyor belt on which a volume of snow passes through stations or individual stations of the device according to the invention. For example, these components can be lug profiles equidistantly arranged on the conveyor belt, protruding from the upper section of the conveyor belt, and interacting with lateral boundary elements for accumulating carbon dioxide snow to form a volume of snow; said boundary elements can also be arranged on the conveyor belt or laterally relative to the conveyor belt.

[0018] The press includes a motor-driven (e.g., pneumatically operated) drive unit and a die. The die, equipped with one or more protruding profiles, is used to press a die cavity into the surface of a volume of snow. The die cavity has one or more recesses corresponding to the one or more profiles. The recesses are particularly suitable for the shape of individual products, especially IQF products; when the device according to the invention is used to freeze products that are liquid or pasty when placed in the mold, the recesses of the die cavity are preferably casting molds, which, after freezing, shape the frozen product.

[0019] Subsequently, a metering device is used to place the product into the recess of the mold cavity, that is, as an individual piece or a predetermined quantity of liquid, molten, paste or slurry product.

[0020] A cooling device is used to completely and thoroughly cool one or more products placed in one or more recesses of a mold cavity. In the cooling device, an atmosphere is preferably maintained at a temperature equal to or slightly above the sublimation temperature of carbon dioxide, so that a certain volume of snow gradually sublimates during the cooling process, leaving the product which now appears as solid blocks separated from each other.

[0021] In a particularly advantageous improvement of the invention, the apparatus for producing carbon dioxide snow, the press, the metering device, and optionally the cooling device are arranged along a conveying device equipped with a conveying mechanism for conveying a volume of snow. For example, the conveying mechanism includes a conveyor belt on which a volume of snow is first produced and then supplied to the press and the metering device. Thus, the same conveying mechanism can also convey a volume of snow, or the product contained therein, to or through the cooling device; however, a preferred embodiment functionally separates the cooling device from other workstations. Therefore, in this embodiment, a separate conveying device is provided for the cooling device on one hand, and separate conveying devices are provided for other workstations of the equipment on the other hand. In this way, the workstations can be combined with different cooling devices; in particular, in this case, a cooling device already existing at the customer's location can continue to be used as a cooling device.

[0022] Cooling tunnels (e.g., in the form of linear or spiral frosting devices) are used as preferred cooling devices. Cooling tunnels preferably operate using liquid carbon dioxide as the cooling medium; however, other cooling concepts are also conceivable, such as using cold air or liquid nitrogen as the cooling medium.

[0023] In an advantageous embodiment of the device according to the invention, the press is equipped with a replaceable die. Therefore, the die can be removed from the press as needed and replaced with a die that leaves different mold cavities in a given volume of snow. Thus, the device can be adapted to different cooling tasks, particularly for manufacturing different IQF products.

[0024] Preferred applications of this invention are in the rapid freezing of food, pharmaceutical, or biotechnology products. In particular, the invention is suitable for the rapid cooling of individual-quantity (IQF) products. For example, the invention is suitable for manufacturing products that can be divided into multiple portions, such as liquid or paste-like foods, like sauces, soups, juices, or cooked vegetables, which can be stored at freezing temperatures (-18°C) and can be removed from the packaging in individual portions for use.

[0025] Exemplary embodiments of the invention will be explained in more detail with reference to the accompanying drawings. (Single drawing) Figure 1 The device according to the invention is shown schematically.

[0026] exist Figure 1 The apparatus 1 shown here for manufacturing frozen products, particularly IQF products, is constructed in an exemplary embodiment as two parts: a mold and metering unit 2 and a cooling device 3.

[0027] The mold and metering unit 2 includes a device 4 for supplying carbon dioxide snow, a press 5, a metering device 6, and a conveying device 8.

[0028] The conveying device 8 is equipped with a rotating conveyor belt 9, the upper section 7 of which runs below the device 4, the press 5, and the metering device 6, and moves in the direction of operation indicated by arrow 10 during operation. The conveyor belt 9 slides between two fixedly mounted vertical side members of the conveying device 8, only the rear side member 11 is shown here. A sealing device (not shown here) can be provided at least in the area of ​​the device 4, which creates a transition between the conveyor belt 9 and the side member 11 that is at least impermeable to carbon dioxide snow particles, without affecting the mobility of the conveyor belt 9. The conveyor belt 9 is equipped with lugs 12 on its rotating outer surface, the lugs being equidistantly arranged, protruding vertically from the upper section 7 of the conveyor belt, and made of a flexible, cold-resistant material (e.g., Teflon).

[0029] For example, the device for providing carbon dioxide snow can be a snow-feeding horn-shaped object arranged above the conveyor belt 9, in which the carbon dioxide snow produced falls directly onto the surface of the conveyor belt 9 surrounding the side member 11 and the two adjacent lug profiles 12.

[0030] In the improved embodiment shown here, device 4 includes a storage container 13 in which a mixture of carbon dioxide gas and carbon dioxide snow is generated by expanding liquid carbon dioxide introduced via supply line 14. As the carbon dioxide gas is removed via exhaust line 15 and optionally supplied for further use, the carbon dioxide snow accumulates in the bottom region of storage container 13. Discharge unit 16 is positioned such that a precisely measured amount of carbon dioxide snow can be measured and placed onto conveyor belt 9 via discharge port 17, which can be opened and closed by means of a device (not shown here). For example, discharge port 17 is arranged directly above the upper section 7 of conveyor belt 9, and the measured amount of snow falls onto conveyor belt 9; or discharge port 17 is positioned laterally relative to conveyor belt 9, and the measured amount of snow is conveyed to conveyor belt 9 via a device such as a chute or conveyor belt (not shown here). Side members 11 and correspondingly adjacent lug profiles 12 on conveyor belt 9 prevent the supplied carbon dioxide snow from escaping laterally, thus forming a vessel that allows the carbon dioxide snow to accumulate to form a volume of snow. Therefore, the volume enclosed by the side member 11 and the two adjacent lug profiles 12 of the conveyor belt 9 is referred to below as the “vessel”.

[0031] Alternatively, the device for providing carbon dioxide snow can be a snow-feeding horn or feeding funnel filled with carbon dioxide snow, which is arranged above the conveyor belt 9, and in this case, the carbon dioxide snow produced or fed therein falls directly into a container (not shown here).

[0032] The press 5 includes a die 19 equipped with a protruding profile 20 and constructed of a solid material (e.g., stainless steel). The base region of the die substantially corresponds to the surface (i.e., the surface of the vessel) surrounded by two successive lug profiles 12 and side members 6. The profiles 20 arranged on the die 19 have, for example, a cylindrical or cubic shape, and their dimensions correspond to the manufacturing unit of the frozen product. The die 19 is detachably mounted on the press 5 and can be replaced with a different die if needed, for example, to manufacture other products. The die 19 is operably connected to, for example, a pneumatically operated drive unit 21 in a manner known per se (not discussed here).

[0033] In the exemplary embodiment shown here, the metering device 6 includes a reservoir 22 for liquid or liquefied (e.g., molten) products and a metering funnel 23 attached to the reservoir.

[0034] Cooling device 3 is a device having a cooling chamber 25 in which a cold atmosphere is maintained. For example, the cooling device is a cooling tunnel (only the starting and ending sections are shown in part here), in which the product to be cooled is conveyed by means of a conveyor 26 in the direction of arrow 24 through the cooling chamber 25 to the outlet 27.

[0035] During operation of device 1, liquid carbon dioxide from tank 28 is introduced into device 4 via supply line 14 and expands therein. The timing and duration can be set at motor control valve 29 by means of a controller (not shown here). During the expansion of liquid carbon dioxide, a mixture of carbon dioxide snow and carbon dioxide gas is generated in storage container 13. While carbon dioxide gas is removed via exhaust line 15, carbon dioxide snow accumulates at the bottom of storage container 13. A metered amount of carbon dioxide snow is supplied by means of discharge unit 16 into vessels, which in their respective cases are defined by two successive lug profiles 12 and two side members 11, and accumulates in said vessels to form a volume of snow 30.

[0036] A volume of snow 30 is conveyed to a press 5 by means of a conveyor belt 9 moving together with its lug profile 12 in the direction of arrow 10. At the press, a die 19 having a profile 20 is briefly pressed into the volume of snow 30, leaving a plurality of recesses 31 in the volume of snow 30, the shape and construction of which correspond to the profile 20. After the recesses 31 are formed, the volume of snow 30 is conveyed to a metering device 6 by means of a conveying device 8, where the recesses 31 are filled with liquid product 32. When the liquid product 32 comes into contact with carbon dioxide snow at an ambient temperature of approximately -78.9°C, the product 32 freezes very rapidly at least at its surface at the edges of the recesses 31. Subsequently, the volume of snow 30 having the filled recesses 31 is conveyed to a cooling device 3.

[0037] The cold atmosphere present in the cooling chamber 25 of the cooling device 3 is used to thoroughly cool the product 32, which is still partially liquid, located in the recess 31. The cold atmosphere is formed by supplying a refrigerant; in the exemplary embodiment shown here, the cryogenic refrigerant is supplied at nozzles 33 arranged in the top region of the cooling chamber 25. In the exemplary embodiment shown here, the cryogenic refrigerant may also be liquid carbon dioxide removed from the tank 28; however, it is also contemplated to use different refrigerants, such as liquid nitrogen, or to use different methods of cooling in the cooling device. The atmosphere temperature in the cooling chamber should be equal to or slightly higher than the sublimation temperature of carbon dioxide, i.e., for example, between -60°C and -78°C.

[0038] During passage through cooling chamber 25, a certain volume of snow 30 gradually sublimates to form carbon dioxide gas, which is extracted in a manner (not shown here) by means of an extraction system present in cooling device 3. Thus, at outlet 27 of cooling device 3, only completely frozen individual final products 34 remain, which are transported away and supplied for further processing or packaging.

[0039] The cooling device 3 can also be an integral part of the equipment 1, and in particular can be connected to the same conveying equipment 8 as other workstations; however, the functional separation of the mold and metering unit 2 from the cooling device 3 shown here allows the mold and metering unit 2 to be combined with a cooling device already present at the customer's site.

[0040] List of reference signs

Claims

1. A method for manufacturing a frozen product, wherein a predetermined amount of carbon dioxide snow is produced and a volume of snow (30) is provided by the carbon dioxide snow, a mold cavity is pressed into the surface of the volume of snow (30) to form at least one recess (31) in the volume of snow (30), at least one product (32) to be cooled is placed in the at least one recess (31), and the volume of snow (30) filled with the at least one product (32) is supplied to a cooling device (3) in which the product is thoroughly cooled.

2. The method according to claim 1, characterized in that, In the cooling device (3), the temperature is maintained such that a certain volume of snow (30) sublimates to form carbon dioxide gas.

3. The method according to claim 1, characterized in that, In order to produce a certain volume of snow (30), pressurized liquid carbon dioxide is expanded at an expansion nozzle, and the carbon dioxide snow produced during this period accumulates in a container.

4. The method according to claim 2, characterized in that, In order to produce a certain volume of snow (30), pressurized liquid carbon dioxide is expanded at an expansion nozzle, and the carbon dioxide snow produced during this period accumulates in a container.

5. The method according to any one of claims 1 to 4, characterized in that, The at least one product (32) placed in the at least one recess (31) is a block product or a liquid or paste product when it is placed in the recess.

6. An apparatus for manufacturing frozen products, the apparatus comprising: means (4) for providing a volume of snow (30); a press (5) equipped with a die (19) having at least one protruding profile (20) and intended for pressing a die cavity into the surface of the volume of snow (30) to form at least one recess (31); a metering device (6) for filling at least one product (32) into the at least one recess (31); and a cooling device (3) for thoroughly cooling the product (32).

7. The device according to claim 6, characterized in that, The device (4) for providing a certain volume of snow includes a snow delivery horn attached to a supply line (14) for liquid carbon dioxide, equipped with an expansion nozzle, and positioned above the work area to provide the certain volume of snow.

8. The device according to claim 6, characterized in that, The device (4) for providing a certain volume of snow includes a storage container (13) for storing carbon dioxide snow and a discharge unit (16) for discharging a metered amount of carbon dioxide snow stored in the storage container (13) and delivering the metered amount of carbon dioxide snow to the work area in order to provide the certain volume of snow.

9. The device according to claim 7, characterized in that, The device (4) for providing a certain volume of snow includes a storage container (13) for storing carbon dioxide snow and a discharge unit (16) for discharging a metered amount of carbon dioxide snow stored in the storage container (13) and delivering the metered amount of carbon dioxide snow to the work area in order to provide the certain volume of snow.

10. The device according to any one of claims 6 to 9, characterized in that, The device (4) for providing carbon dioxide snow, the press (5) and the metering device (6) are arranged along the conveying equipment (8), which is equipped with a device for conveying the volume of snow (30).

11. The device according to any one of claims 6 to 9, characterized in that, The cooling tunnel serves as the cooling device (3).

12. The device according to claim 10, characterized in that, The cooling tunnel serves as the cooling device (3).

13. The device according to any one of claims 6-9 and 12, characterized in that, The die (19) can be interchangeably mounted on the press (5).

14. The device according to claim 10, characterized in that, The die (19) can be interchangeably mounted on the press (5).

15. The device according to claim 11, characterized in that, The die (19) can be interchangeably mounted on the press (5).

16. The method according to any one of claims 1 to 5 or the apparatus (1) according to any one of claims 6 to 15 for use in rapidly frozen food products, pharmaceutical products or biotechnology products.

17. The use according to claim 16, characterized in that, The food product, pharmaceutical product, or biotechnology product is an IQF product.

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