Method and apparatus for the thermal treatment of a fat or oil

Abstract

The invention relates to a method for the thermal treatment of a product in the form of a fat or oil with a water content of at most 10% for the inactivation of microorganisms contained in the product, comprising the steps: a) Heating the product in a first heat exchanger to a temperature in the range of 50°C to 85°C, b) Subsequent heating of the product by steam injection in a steam injector to a temperature in the range of 95°C to 140°C, whereby the amount of liquid supplied by the steam injection in the form of condensate is monitored and / or controlled during the steam injection, c) Subsequently keeping the product hot in a heat holder, d) Subsequent cooling of the product in a flash cooling tank by vacuum degassing to a temperature in the range of 75°C to 85°C, e) Subsequent cooling of the product in a second heat exchanger to an outlet temperature above the melting point of the product. The invention further relates to a corresponding device.

Description

[0001] The invention relates to a method and a device for the thermal treatment of a product in the form of a fat or oil with a water content of a maximum of 10% for the inactivation of microorganisms contained in the product.

[0002] When using fats or oils, it is essential to prevent microbiological spoilage. Fats and oils can be reliably protected from microbiological contamination in their initial state. However, if a fat or oil comes into contact with various surfaces that may be microbiologically contaminated during different storage and transport steps, for example, in a tank truck, contamination with microorganisms can occur. This is especially true in conjunction with prolonged storage and multiple transport steps. Fats or oils with a low water content, such as anhydrous milkfat, pose a low risk of microbiological spoilage even in the event of microbiological contamination due to their low water activity.However, if such a contaminated fat or oil is mixed into a final product as an ingredient in subsequent processing steps, the previously occurring microbiological contamination can lead to spoilage problems in the final product. This is especially true because the water activity in the final product is regularly higher, allowing for critical bacterial growth. Similar problems can also occur in the production of plant-based milk alternatives, to which vegetable fats are frequently added, due to microbiological contamination of the fats or oils used.

[0003] Thermal treatment of conventional products is generally carried out through pasteurization. For example, if hot milk is pasteurized at 72°C for 30 seconds, by definition all pathogenic germs are killed. However, this is not possible for the products to be treated here, which are fats or oils with a low water content, either thermally or through separation. The reason is that, due to the very low water content in the product, the low water activity increases the resistance of the bacteria, and irreversible denaturation does not occur.

[0004] Based on the prior art described above, the invention therefore aims to provide a method and a device of the type mentioned above with which a reliable and sufficient inactivation of microorganisms in fats or oils with low water content is achieved.

[0005] The invention solves the problem through independent claims 1 and 12. Advantageous embodiments can be found in the dependent claims, the description and the figures.

[0006] For the method according to the invention, the problem is solved by the following steps: a) Heating the product in a first heat exchanger to a temperature in the range of 50°C to 85°C, b) Subsequent heating of the product by steam injection in a steam injector to a temperature in the range of 95°C to 140°C, whereby the amount of liquid supplied by the steam injection in the form of condensate is monitored and / or controlled during the steam injection, c) Subsequently keeping the product hot in a heat holder, d) Subsequent cooling of the product in a flash cooling tank by vacuum degassing to a temperature in the range of 75°C to 85°C, e) Subsequent cooling of the product in a second heat exchanger to an outlet temperature above the melting point of the product, preferably to an outlet temperature in the range of 45°C to 65°C, more preferably from 45°C to 55°C.

[0007] The process according to the invention first involves heating the product in a first heat exchanger to a temperature in the range of 50°C to 85°C. The product, in the form of a fat or oil with a low water content, is preferably in a liquid state before entering the first heat exchanger. It may therefore have a temperature above its melting point. In particular, the product, in the form of a fat or oil, may have an inlet temperature in the range of 45°C to 65°C, more particularly 45°C to 55°C, for example approximately 50°C, before entering the first heat exchanger. In process step e), the product can be cooled back down to this inlet temperature as the outlet temperature. Upon exiting after treatment, the product is also preferably in a liquid state. It is cooled in the second heat exchanger to a temperature above its melting point.

[0008] In process step b), which follows process step a), the fat or oil is heated to a temperature in the range of 95°C to 140°C by steam injection in a steam injector. The fat or oil can, for example, be heated to a temperature in the range of 95°C to 125°C. Preferably, the fat or oil is heated to a temperature of at least 100°C, and more preferably at least 120°C. The steam injector can, for example, be configured as described in EP 1980152 B1 or in EP 3011246 B1.

[0009] In the next step (c), the grease or oil is kept hot in a holding tank, for example at a temperature between 95°C and 140°C. After the heating process in the steam injector, the grease or oil enters the holding tank at essentially the same temperature and can be kept at that temperature by the tank.

[0010] After being held hot, in process step d) the fat or oil is cooled in a flash cooling tank by vacuum degassing to a temperature in the range of 75°C to 85°C. In a flash cooling tank, the steam or liquid introduced during steam injection is removed from the product by applying a corresponding vacuum, thereby cooling the product rapidly and significantly. Such flash cooling tanks are known per se.

[0011] In the subsequent process step e), the product is then cooled in a second heat exchanger to an outlet temperature above its melting point, for example, to an outlet temperature in the range of 45°C to 65°C, particularly from 45°C to 55°C. The heating and cooling in the heat exchangers is indirect.

[0012] As already explained, the fat or oil treated with the inventive method has a low water content of no more than 10%. The product can have a water content of up to 5%. It can be, in particular, a vegetable or animal fat or oil. The fat content of the fat or oil can be at least 90%, preferably at least 95%.

[0013] In the thermal treatment of conventional products, the amount of steam supplied to the product in a steam injector is adjusted based on the heating temperature to be achieved and is therefore secondary to the process carried out.

[0014] This is different with regard to the product to be treated according to the invention, which is a fat or oil with a low water content. The amount of steam that condenses into the product during steam injection is critical for the success of the process, and not only because of the heating temperature it ensures. Rather, the addition of liquid, especially water, in the form of condensate is relevant to the desired inactivation of microorganisms in the product to be treated according to the invention, since the water activity in the product is increased by adding water, especially in the form of condensate.

[0015] For this reason, according to the invention, process step b) provides that the amount of liquid supplied as condensate during steam injection is monitored and / or controlled. Thus, not only is the heating temperature of the product monitored and controlled during steam injection, as is usually the case, but also the amount of liquid, particularly water, supplied to the product. In this way, microorganisms contained in the product can be sufficiently inactivated, and in particular killed, without increasing the water activity of the product in a way that counteracts the desired inactivation of the microorganisms. The amount of liquid supplied as condensate during steam injection can be monitored and / or controlled in such a way that saturated steam is supplied to the product for optimal parameterization of the energy input.

[0016] The invention thus enables the efficient inactivation or killing of microorganisms contained in fats or oils with a low water content of at most 10%, even during thermal treatment. This is achieved by taking into account the specific characteristics of the fats and oils to be treated according to the invention, particularly during heating in the steam injector. The risk of microbiological spoilage, even when the fat or oil is added to other products to form a final product, can be reliably minimized.

[0017] Furthermore, the invention can increase process reliability and flexibility, minimize energy consumption and generate a positive environmental effect, in particular by preserving a valuable product.

[0018] Experiments carried out using the method according to the invention confirm the advantages described above. In experiments, colony-forming units (CFU) of over 500,000 per gram were measured in untreated clarified butter for microorganisms, in this case subspecies of Enterococcus. After carrying out the method according to the invention, in which the clarified butter was heated to a temperature of 95°C in process step b), only 30 colony-forming units per gram could still be detected. In further experiments, in which the product was heated to 125°C and to 140°C in process step b), values ​​of less than 10 CFU per gram were obtained.

[0019] The product treated according to the invention can be anhydrous milkfat. Anhydrous milkfat is produced from cream or butter and has a milk fat content of at least 99.8%. It is usually packaged in smaller containers or drums of approximately 200 kg to 500 kg and must be protected from oxidation. Anhydrous milkfat can be thermally treated particularly effectively using the process according to the invention.

[0020] In a further embodiment, it can be provided that in step b) at least one of the parameters vapor pressure, vapor temperature, vapor quantity, or discharged condensate is monitored and / or controlled to monitor and / or regulate the amount of liquid supplied in the form of condensate, and / or that the vapor is dehydrated before vapor injection in step b). This embodiment allows the vapor quantity or vapor state (e.g., saturated or superheated) to be adjusted as desired during vapor injection in the vapor injector, taking into account the product being treated. Dehydration of the vapor can also be performed, and the amount of separated condensate can be recorded so that the actual amount of vapor introduced into the product can be determined. The aforementioned embodiments can, for example, ensure or control the presence or generation of saturated vapor in the vapor injector.

[0021] According to a further embodiment, the product can pass through a static mixer after step b) and before step c). A static mixer is a mixing device in which the mixing is effected solely by the flow motion of the product passing through the mixer. No moving elements are provided in the mixer. In this way, undesirable stress or imposition on the product being processed can be avoided. At the same time, improved mixing of steam with the product is ensured. Depending on the design of the heat holder, it may also be possible to further enhance the mixing by introducing flow baffles or flow breakers into the static mixer. For particularly efficient mixing, it is especially preferred if the grease or oil passes through the static mixer as a turbulent flow.

[0022] In a further embodiment, the flash cooling tank may have an adjustable product inlet, and the product inlet may be adjusted in step d) depending on the amount of liquid supplied in the form of condensate in step b). In particular, the product inlet may be adjusted so that the product is distributed tangentially across the inner surface of one wall of the flash cooling tank upon entering. The product inlet may also have an inlet nozzle whose inclination and / or angle of entry for product into the flash cooling tank is adjustable, and in step d), the inclination and / or angle of entry of the inlet nozzle may be adjusted depending on the amount of liquid supplied in the form of condensate in step b).

[0023] In the aforementioned configuration, the product inlet or inlet nozzle of the flash cooling tank is designed such that the direction of product entry into the steam injector can be adjusted depending on the amount of water added during steam injection. In particular, by adjusting the inclination and / or the inlet angle of the nozzle, the product can be guided more or less far or for a shorter or longer time along an inner wall of the flash cooling tank. This allows for adjustment of the degassing effect, and thus the cooling of the product and the removal of liquid from the product.In particular, adjusting the product inlet based on the amount of liquid previously supplied during steam injection ensures a sufficiently large surface area for the tangentially entering product to spread across the inner wall of the flash cooling tank, thus achieving adequate degassing. By adjusting the product inlet according to the invention based on the amount of liquid supplied as condensate in the steam injector, and optionally also based on the product properties, especially the water and / or fat content, the cooling process in the flash cooling tank can be controlled and flexibly, and furthermore, with reduced water consumption and energy savings for the flash cooling tank's vacuum pump.

[0024] In a further embodiment, the liquid level in the flash cooling tank can be monitored and / or controlled during the cooling process in step d). The position of the adjustable product inlet of the flash cooling tank can be taken into account to control the liquid level. The liquid level in the flash cooling tank provides information about the amount of liquid removed from the product. In this way, the desired degassing effect can be achieved while ensuring the removal of the liquid added in the vapor injector. This is accomplished by monitoring the liquid level and, for example, adjusting the product inlet based on the measured liquid level to remove the desired amount of liquid from the product.

[0025] The product can be cooled in the flash cooling tank in step d) to a temperature lower than its temperature upon entering the steam injector in step b). During the flash cooling by vacuum degassing in step d), the previously introduced steam is removed from the product to cool it. By controlling the outlet temperature of the flash cooling tank to a value below the inlet temperature of the steam injector, it is ensured that the entire quantity of liquid introduced during steam injection is removed from the product in the flash cooling tank.

[0026] In a further embodiment, the product can be pumped between the flash cooling tank and the second heat exchanger. The pump is designed to pump the product from the flash cooling tank, i.e., against the applied vacuum. Any rotating components of the pump are preferably driven at a low rotational speed to minimize the mechanical stress on the product, especially the grease phase, which is subjected to stress during the thermal treatment.

[0027] The invention also solves the problem by means of a device for the thermal treatment of a product in the form of a fat or oil with a water content of a maximum of 10% for the inactivation of microorganisms contained in the product, comprising a first heat exchanger, a steam injector, a hot holder, a flash cooling tank and a second heat exchanger, wherein the device is configured to carry out the method according to the invention.

[0028] The device may include a control unit for controlling its components. It may also include a regulating unit for monitoring and / or controlling the amount of liquid supplied to the steam injector as condensate via steam injection, and / or for dehydrating the steam prior to injection, and / or for monitoring and / or controlling the liquid level in the flash cooling tank. Furthermore, it may include an adjustment unit for adjusting the product inlet of the flash cooling tank. It may also include a static mixer and / or a pump for transferring the product between the flash cooling tank and the second heat exchanger. The control unit may also include the adjustment unit. The control unit and the regulating unit may be combined into a single control and regulating unit.

[0029] An embodiment of the invention is explained in more detail below with reference to a drawing. The single figure schematically shows a device according to the invention for carrying out the method according to the invention.

[0030] The device comprises a receiving vessel 10 into which a product to be thermally treated, namely a fat or oil with a water content of no more than 10%, is fed via a first feed line 11. The product may be clarified butter. From the receiving vessel 10, the product to be treated is fed by means of a first pump 12 to a first heat exchanger 14, in which it is indirectly heated to a temperature in the range of 50°C to 85°C. The product is then fed to a steam injector 16, in which it is heated by steam injection to a temperature in the range of 95°C to 140°C. Heated steam is supplied to the steam injector 16 via a second feed line 18 to heat the product contained therein.A first flow meter 20 for measuring the quantity of steam supplied via the second supply line 18, a pressure sensor 22 for measuring the steam pressure of the steam supplied via the second supply line 18, and a temperature sensor 24 for measuring the steam temperature of the steam supplied via the second supply line 18 are connected to the second supply line 18. The measured values ​​of the first flow meter 20, the pressure sensor 22, and the temperature sensor 24 are connected to a control and / or regulating device 25 of the apparatus, which controls the components of the apparatus. A drainage device 26 is also provided on the second supply line 18, through which the steam supplied to the steam injector 16 is drained. The condensate discharged via the drainage device 26 is directed to a drain 27.The amount of condensate discharged is measured by a second flow meter 28, the readings of which are also available at the control and / or regulating unit 25. Based on these readings, the control and / or regulating unit 25 regulates the parameters measured by the various sensors. In particular, the regulation is carried out such that saturated steam is supplied to the product during steam injection.

[0031] After heating in the steam injector 16, the product first passes through a static mixer 30 for homogenization and is then kept hot in a holding tank 32. After the holding tank 32, the product enters a flash cooling tank 34, where it is cooled to a temperature between 75°C and 85°C by vacuum degassing. During vacuum degassing, the steam supplied to the product in the steam injector 16 is extracted via the degassing line 36 and conveyed to a drain 40 by a second pump 38. The heat removed in this process can be utilized in subsequent process steps via a degassing heat exchanger 42.

[0032] From the flash cooling tank 34, the product is then pumped by a third pump 44 to a second heat exchanger 46. The third pump 44 is designed, on the one hand, to pump the product against the applied negative pressure from the flash cooling tank 34. On the other hand, rotating components of the third pump 44 are driven as slowly as possible to minimize mechanical stress on the product, especially the fat content.

[0033] Following the second heat exchanger 46, the product enters a third heat exchanger 48, from which it can be discharged via an outlet line 50 for further use. In the second and third heat exchangers 46 and 48, the product is indirectly cooled to an outlet temperature in the range of 45°C to 65°C, particularly 45°C to 55°C. The second heat exchanger 46 is connected to the first heat exchanger 14 via a heat exchanger line 52. An energy heat exchanger 54 is arranged in the heat exchanger line 52. Steam is supplied to this heat exchanger via a supply line 56, and condensate is discharged via a condensate line 58 and conveyed to a drain 60.

[0034] The flash cooling tank 34 has an adjustable product inlet 62, which is adjusted depending on the amount of liquid supplied in the form of condensate via the steam injector 16, such that the product is distributed tangentially over the inner surface of a wall of the flash cooling tank 34 upon inlet, as illustrated in the figure at reference numeral 64. In particular, the product inlet 62 has an inlet nozzle whose inclination and / or angle of entry for product into the flash cooling tank 34 is adjustable. The inclination and / or angle of entry of the inlet nozzle are adjusted, depending on the amount of liquid supplied in the form of condensate via the steam injector 16, to ensure sufficient degassing, so that the previously supplied amount of liquid is removed from the product. During the cooling process in the flash cooling tank 34, the liquid level in the flash cooling tank 34 can be monitored and / or controlled.The position of the adjustable product inlet 62 can be taken into account to regulate the liquid level, or the position of the adjustable product inlet 62 can be adjusted depending on the liquid level. This can also be done by the control and / or regulating device 25. Reference sign 10 collection containers 11 First feed line 12 First pump 14 First heat exchanger 16 steam injector 18 Second feed line 20 First flow meter 22 pressure sensors 24 temperature sensors 25 Control and / or regulating device 26 Drainage system 27 Drain 28 Second flow meter 30 mixers 32 hot holders 34 Flash cooling tank 36 Degassing line 38 Second pump 40 Drain 42 Degassing heat exchangers 44 Third Pump 46 Second heat exchanger 48 Third heat exchanger 50 Exit line 52 Heat exchanger line 54 energy heat exchangers 56 Third feed line 58 Condensate line 60 Drain 62 Product inlet QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1980152 B1

[0008] EP 3011246 B1

[0008]

Claims

[1] Method for the thermal treatment of a product in the form of a fat or oil with a water content of no more than 10% for the inactivation of microorganisms contained in the product, comprising the steps of: a) Heating the product in a first heat exchanger (14) to a temperature in the range of 50°C to 85°C, b) Subsequent heating of the product by steam injection in a steam injector (16) to a temperature in the range of 95°C to 140°C, wherein the amount of liquid supplied by the steam injection in the form of condensate is monitored and / or controlled during the steam injection, c) Subsequent holding of the product in a heat holder (32), d) Subsequent cooling of the product in a flash cooling tank (34) by vacuum degassing to a temperature in the range of 75°C to 85°C, e) Subsequent cooling of the product in a second heat exchanger (46) to an outlet temperature above the melting point of the product. [2] Method according to claim 1, characterized by that the product has a maximum water content of 5%. [3] Method according to any one of the preceding claims, characterized by that the product is pure butterfat. [4] Method according to any one of the preceding claims, characterized by , that in step b) at least one of the parameters vapor pressure, vapor temperature, vapor quantity, or condensate quantity is monitored and / or controlled to monitor and / or control the amount of liquid supplied in the form of condensate, and / or that in step b) the vapor is dewatered before the vapor injection. [5] Method according to any one of the preceding claims, characterized by , that the product passes through a static mixer (30) after step b) and before step c). [6] Method according to claim 5, characterized by , that the product passes through the static mixer (30) as turbulent flow. [7] Method according to any one of the preceding claims, characterized by , that the flash cooling tank (34) has an adjustable product inlet (62), and that the product inlet (62) is adjusted in step d) depending on the amount of liquid supplied in step b) in the form of condensate. [8] Method according to claim 7, characterized by , that the product inlet (62) has an inlet nozzle adjustable in its inclination and / or inlet angle for product into the flash cooling tank (34), and that in step d) the inclination and / or inlet angle of the inlet nozzle is adjusted depending on the amount of liquid supplied in step b) in the form of condensate. [9] Method according to any one of the preceding claims, characterized by, that during the cooling process in step d) a liquid level in the flash cooling tank (34) is monitored and / or controlled. [10] Method according to any one of the preceding claims, characterized by , that the product in the flash cooling tank (34) in step d) is cooled to a temperature lower than the temperature of the product when entering the steam injector (16) in step b). [11] Method according to any one of the preceding claims, characterized by that the product is conveyed by means of a pump (44) between the flash cooling tank (34) and the second heat exchanger (46). [12] Device for the thermal treatment of a product in the form of a fat or oil with a water content of at most 10% for the inactivation of microorganisms contained in the product, comprising a first heat exchanger (14), a steam injector (16), a hot holder (32), a flash cooling tank (34) and a second heat exchanger (46), characterized bythat it is trained to carry out the procedure according to one of the preceding claims.

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