A low temperature concentration process with reduced crystallization entrainment

Abstract

The application relates to a low-temperature concentration method for reducing crystallization entrainment. The low-temperature concentration method for reducing crystallization entrainment described in the application introduces small-molecule gas to form hydrate crystal nuclei or small crystals to serve as the crystal seeds of the freeze concentration before the stage of the freeze concentration crystallization phase change, can reduce the freeze concentration crystallization supercooling degree, and promotes the freeze concentration to occur. In the stage of the freeze concentration phase change, the gas is continuously introduced to enhance the heat transfer, increase the nucleation points, promote the crystallization to occur, form more small ice crystals, effectively reduce the generation of large ice crystals, and reduce the entrainment rate. Compared with single freeze concentration, the low-temperature concentration method for reducing crystallization entrainment adopting the embodiment of the application saves time by more than 10%, reduces the ice crystal entrainment rate by more than 10%, and improves the quality by more than 15%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technology of concentrating liquid materials in the fields of biopharmaceuticals, food, chemical synthesis, etc., in particular to a low-temperature concentration method for reducing the entrainment rate of crystallization. BACKGROUND

[0002] Concentration is an important means commonly used in the fields of biopharmaceuticals, food processing, chemical synthesis, etc. Concentrated liquids are widely circulated as a semi-finished product or product. High-efficiency, high-quality, and low-cost concentration methods have always been an urgent demand in the concentration industry.

[0003] Traditional liquid concentration methods include membrane concentration, evaporation concentration, and freeze concentration. Freeze concentration is a concentration method that uses the solid-liquid phase equilibrium principle between ice and aqueous solution to cool the dilute solution until part of the water in the solution freezes into ice, and the ice crystals are separated. It is suitable for the concentration and separation of liquid food, heat-sensitive pharmaceuticals and biological products, wastewater treatment, seawater desalination, etc. The commonly used method in industry is suspended freeze concentration, which achieves concentration by growing and separating ice crystals suspended and dispersed in the mother liquor. It mainly includes four processes: seed crystal generation, crystal growth, solid-liquid separation, and washing crystals. The number, size, and shape of ice crystals are the key to the entire technology. The prevention of small ice crystals adhering to the liquid in the seed crystal process, the avoidance of secondary nucleation during ice crystal growth, and the inhibition of ice crystal growth rate are the main factors affecting the concentration quality, i.e., to obtain ideal ice crystals. Large ice crystals formed in disorder have high entrainment rates, which can cause loss of solutes and loss of nutrients, and complex washing steps are required. In the washing process, irreversible loss of solutes will also occur to some extent, which will ultimately significantly affect the quality of the concentrated juice.

[0004] Hydrate concentration is a concentration method that forms a cage-shaped structure similar to ice crystals by guest gas molecules and host water molecules in the solution under certain pressure and temperature, and then separates the solid and liquid to obtain concentrated liquid. The formation of hydrates includes two stages of crystal nucleation and crystal growth. In the early stage of nucleation, gas molecules enter the solution, and as the gas-liquid mass transfer progresses, the gas bubbles gradually become smaller, and the gas molecules enter the cage-shaped pore structure formed by the host water molecules, and nucleation occurs. The host and guest molecules are associated with each other through van der Waals forces, and gradually form stable cages, and finally complete crystallization.

[0005] Hydrate concentration, similar to the currently recognized best method of freeze concentration, also suffers from the problem of solute loss due to crystal entrainment. During crystal formation (forming cage-like structures), the solute in the solution is easily entrained or even buried, and the hydrate entrainment rate is one of the main factors limiting its widespread application. However, compared to freeze concentration, it does not require sub-zero temperatures and consumes less energy. Therefore, effectively controlling the formation rate, shape, and size of hydrate crystals to obtain stable, abundant, and pure hydrate crystals, thereby achieving a concentrated solution with high concentration and low entrainment rate, is crucial for promoting the application of hydrate-based liquid food concentration technology.

[0006] Therefore, the above-mentioned concentration technologies all have some shortcomings, mainly as follows:

[0007] (1) Evaporation concentration has high concentration efficiency, but it seriously damages the heat-sensitive functional and nutritional components in the material.

[0008] (2) Freeze concentration has relatively high concentration quality, but the low temperature requirements of freezing make the concentration energy consumption high, the time long, the entrainment rate high, and it also requires crystal washing operation. In addition, it still needs to be sterilized in order to store the finished product concentrate for a long time, and its application is relatively limited.

[0009] (3) The hydrate concentration has a high entrainment rate and limited bactericidal effect on the material, resulting in microbial sublethality. Additional bactericidal treatment is required for long-term storage. Summary of the Invention

[0010] Based on this, this application provides a low-temperature concentration method to reduce crystallization entrainment. This method optimizes the timing, quantity, and distribution of gas introduction, coupling gas hydrate concentration and freeze-concentration to improve the crystallization process, reduce solute entrainment, and thus enhance the purity and nutritional quality of the product.

[0011] This application provides a low-temperature concentration method for reducing crystal entrainment rate, comprising the following steps:

[0012] S100. The liquid material is pre-cooled to control the temperature of the inner cavity of the concentration processor to be consistent with the pre-cooling temperature of the liquid material.

[0013] S200: The pre-cooled liquid material is fed into the inner cavity of the concentration processor;

[0014] S300. Introduce small molecule gas into the inner cavity of the concentration processor while stirring the liquid material, and adjust the pressure in the inner cavity of the concentration processor to the first pressure.

[0015] S400: Continue to convey the pre-cooled liquid material into the inner cavity of the concentration processor to reduce the temperature of the inner cavity of the concentration processor;

[0016] S500, Continue to input small molecule gas into the inner cavity of the concentration processor, adjust the pressure in the inner cavity of the concentration processor to the second pressure, and increase the stirring speed, wherein the second pressure is lower than the first pressure;

[0017] S600. When the liquid material in the inner cavity of the concentration processor reaches the target concentration, it is discharged from the inner cavity of the concentration processor, and all concentrated mother liquor is collected and the upper ring-shaped ice crystals are removed.

[0018] In one embodiment, in step S100, the liquid material is pre-cooled to a temperature of 0.5-8°C; in step S400, the temperature of the inner cavity of the concentration processor is reduced to -1 to -12°C.

[0019] In one embodiment, in step S100, when the pre-cooled liquid material is fed into the inner cavity of the concentration processor, the volume of the liquid material is controlled to occupy 1 / 4-2 / 5 of the total volume of the inner cavity of the concentration processor; in step S400, the pre-cooled liquid material is continued to be fed into the inner cavity of the concentration processor, and the volume of the liquid material is controlled to occupy 1 / 2-4 / 5 of the total volume of the inner cavity of the concentration processor.

[0020] In one embodiment, in step S300, stirring is achieved by setting a stirrer in the inner cavity of the concentration processor, and the stirring speed of the stirrer is set to 500-1500 rpm; in step S500, small molecule gas is continued to be introduced during the cooling process, and the stirring speed of the stirrer is increased to 1500-2500 rpm.

[0021] In one embodiment, in step S300, the internal pressure of the concentration processor is adjusted to 3-10 MPa; in step S500, the internal pressure of the concentration processor is adjusted to 2-5 MPa.

[0022] In one embodiment, the small molecule gas is at least one of the following: CO2, C2H4, CH4, N2.

[0023] Compared with the prior art, the low-temperature concentration method for reducing crystal entrainment rate according to the embodiments of this application has the following advantages and beneficial effects:

[0024] Before the phase transition of freeze-concentration crystallization, small molecule gas is introduced to form hydrate nuclei or small crystals, which can act as seed crystals for freeze-concentration. This can reduce the supercooling of freeze-concentration crystallization and promote the occurrence of freeze-concentration.

[0025] During the freeze-concentration phase change stage, the continued introduction of gas enhances heat transfer, increases nucleation sites, promotes crystallization, and forms more and smaller ice crystals, effectively reducing the formation of large ice crystals and lowering the entrainment rate.

[0026] The low-temperature concentration method for reducing crystal entrainment rate according to the embodiments of this application saves more than 10% of time, reduces ice crystal entrainment rate by more than 10%, and improves quality by more than 15% compared with single freeze concentration. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the steps of a low-temperature concentration method for reducing crystal entrainment rate in one embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the apparatus used to implement a low-temperature concentration method for reducing crystal entrainment rate according to an embodiment of this application.

[0029] Explanation of icon numbers:

[0030] 10. Concentrator; 11. Inner cavity; 111. Stirrer; 112. Pressure sensor; 113. Temperature sensor; 114. Liquid level sensor; 115. Concentration sensor; 116. Camera; 117. Gas valve; 20. Feed tank; 30. Material transfer pump; 40. Gas transfer pump; 50. Collector. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. Furthermore, the embodiments described in the following exemplary embodiments do not limit the invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of this invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular forms “a,” “the,” and “the” used in this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0033] It should be understood that although the terms first, second, third, etc., may be used in this invention to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of this invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0034] In response to the technical problems mentioned in the background art, this application provides a low-temperature concentration method to reduce crystal entrainment rate. This method optimizes the timing, quantity and distribution of gas introduction, and couples gas hydrate concentration and freeze concentration to improve the crystallization process, reduce solute entrainment, minimize crystal entrainment rate, ensure concentration rate and concentration quality, thereby improving product purity and nutritional quality.

[0035] The following describes in more detail a low-temperature concentration method for reducing crystal entrainment rate according to an embodiment of the present invention, but should not be considered as a limitation thereof.

[0036] This application provides a low-temperature concentration method for reducing crystal entrainment rate. The method can be applied to fields such as biopharmaceuticals, food, and chemical synthesis, but is not limited thereto.

[0037] like Figure 1 As shown, Figure 1 This is a flowchart illustrating a low-temperature concentration method for reducing crystal entrainment rate according to an exemplary embodiment of this application. The low-temperature concentration method for reducing crystal entrainment rate provided in this embodiment includes the following steps:

[0038] S100, pre-cooling the liquid material, controlling the temperature of the inner cavity of the concentration processor to be consistent with the pre-cooling temperature of the liquid material;

[0039] S200, the pre-cooled liquid material is fed into the inner cavity of the concentration processor;

[0040] S300, small molecule gas is introduced into the inner cavity of the concentration processor, while the liquid material is stirred, and the pressure in the inner cavity of the concentration processor is adjusted to the first pressure;

[0041] S400, continue to deliver the pre-cooled liquid material to the inner cavity of the concentration processor to reduce the temperature of the inner cavity of the concentration processor;

[0042] S500, continue to input small molecule gas into the inner cavity of the concentration processor, adjust the pressure in the inner cavity of the concentration processor to the second pressure, and increase the stirring speed, wherein the second pressure is lower than the first pressure;

[0043] S600, when the liquid material in the inner cavity of the concentration processor reaches the target concentration, it is discharged from the inner cavity of the concentration processor, all concentrated mother liquor is collected, and the upper ring-shaped ice crystals are removed.

[0044] The liquid material described in this application can be an intermediate or final substance produced in fields such as biopharmaceuticals, food processing, and chemical synthesis. The specific parameters such as temperature, pressure, and stirring speed in the above steps can be set according to different liquid materials.

[0045] In a preferred embodiment, in step S100, the liquid material is pre-cooled to a temperature of 0.5-8°C. In step S100, when the pre-cooled liquid material is fed into the inner cavity of the concentration processor, the volume of the liquid material is controlled to occupy 1 / 4-2 / 5 of the total volume of the inner cavity of the concentration processor. In step S300, the small molecule gas is used to react with water molecules to form hydrate crystals, acting as seed crystals for ice crystals. Preferably, the small molecule gas in this application can be CO2, C2H4, CH4, N2, etc., or other small molecular weight gases capable of forming hydrates. In step S300, preferably, stirring is achieved by installing a stirrer in the inner cavity of the concentration processor, with a rotation speed set to 500-1500 rpm, and the pressure in the inner cavity of the concentration processor is adjusted to 3-10 MPa, that is, the first pressure range is 3-10 MPa. In step S400, the liquid material in the inner cavity of the concentration processor can be monitored in real time by monitoring the phase change curve and temperature curve, as well as by observing the online camera. The liquid material undergoes a phase change to form small crystal seeds, and the pre-cooled liquid material is then continuously transported to the inner cavity of the concentration processor. A temperature sensor can be installed in the inner cavity of the concentration processor to monitor the temperature curve, and a pressure sensor can be installed to monitor the pressure. The real-time phase change curve can be obtained by judging the changes in temperature and pressure.

[0046] In step S400, preferably, the volume of the liquid material is controlled to occupy 1 / 2 to 4 / 5 of the total volume of the inner cavity, and the temperature of the inner cavity of the concentration processor is reduced to -1 to -12°C.

[0047] In step S500, small molecule gas continues to be introduced during the cooling process, the internal pressure of the concentration processor is adjusted to 2-5 MPa, and the stirring speed of the stirrer is increased to 1500-2500 rpm. In step S600, a concentration sensor can be installed in the internal cavity of the concentration processor to monitor the concentration of the liquid material in real time.

[0048] Compared with the prior art, the low-temperature concentration method for reducing crystal entrainment rate according to the embodiments of this application has the following advantages and beneficial effects:

[0049] (1) In the stage before the phase change of freezing concentration crystallization, small molecule gas is introduced to form hydrate crystal nuclei or small crystals, which can serve as seed crystals for freezing concentration, thereby reducing the supercooling of freezing concentration crystallization and promoting freezing concentration.

[0050] (2) During the freeze-concentration phase change stage, the gas is continued to be introduced, which enhances heat transfer, increases nucleation points, promotes crystallization, and forms more and smaller ice crystals, effectively reducing the formation of large ice crystals and reducing the entrainment rate.

[0051] The low-temperature concentration method for reducing crystal entrainment rate according to the embodiments of this application saves more than 10% of time, reduces ice crystal entrainment rate by more than 10%, and improves quality by more than 15% compared with single freeze concentration.

[0052] like Figure 2 As shown, Figure 2 The apparatus used in the low-temperature concentration method for reducing crystallization entrainment rate according to the embodiments of this application includes a concentration processor 10, a feed tank 20, a material transfer pump 30, a gas transfer pump 40, and a collector 50, all in the conventional technology. The concentration processor 10 has an inner cavity 11, and the temperature and pressure of its inner cavity can be adjusted. A stirrer 111, a pressure sensor 112, a temperature sensor 113, a liquid level sensor 114, a concentration sensor 115, and a camera 116 are installed in the inner cavity 11. The concentration processor 10 also has an exhaust pipe connecting its inner cavity 11 to the outside, and an air valve 117 is installed on the exhaust pipe. The above are used to detect the pressure, temperature, liquid level, and concentration of the liquid material in the inner cavity 11. Real-time phase transition curves are obtained through temperature and pressure changes.

[0053] Specifically, the liquid material can be pre-cooled in a cold storage. The feed tank 20 is used to transfer and store the pre-cooled liquid material. The material transfer pump 30 is used to transport the liquid material from the feed tank 20 to the inner cavity 11. The gas transfer pump 40 is used to introduce small molecule gas into the inner cavity 11. The collector 50 is used to collect all the concentrated mother liquor discharged from the inner cavity 11 and remove the upper layer of ring-shaped ice crystals. In a preferred embodiment, a condensation circulation system can be set up to circulate cooling between the feed tank 20 and the inner cavity of the concentration processor, ensuring that the temperature of both is consistent with the temperature of the pre-cooled liquid material.

[0054] In some embodiments, a controller is also included. This controller may be a microcontroller, PLC, computer, etc., and the operation of the aforementioned equipment is controlled by the controller.

[0055] The following detailed description of a low-temperature concentration method for reducing crystal entrainment rate according to several specific embodiments of this application is provided. Unless otherwise specified in the embodiments of this application, conventional conditions or conditions recommended by the manufacturer shall apply. Raw materials and reagents used, unless otherwise specified, are all commercially available conventional products.

[0056] Example 1

[0057] Lemons at 8-9 tenths ripeness are peeled and juiced to obtain lemon juice with a solids content of 8°Brix. This juice is then pre-cooled to 5°C in a cold storage. A condenser circulation system is activated to ensure the temperature of the feed tank and the concentrator's interior matches the pre-cooled lemon juice temperature. 2.5L of pre-cooled lemon juice is pumped from the feed tank into the concentrator's interior, filling it to 1 / 4 of its volume. CO2 is introduced, and the stirring device is turned on at 500 rpm. Once the pressure reaches 3 MPa, the gas valve is closed. After monitoring for a phase change, the gas valve is opened to release the gas. Another 2.5L of pre-cooled lemon juice is added, lowering the temperature of the concentrator's interior to -1°C. CO2 is continued to be introduced until the concentrator's pressure reaches 2 MPa. The gas valve is then closed, and the stirring speed is increased to 1500 rpm. When the concentration of the concentrated juice in the interior reaches 26°Brix, the concentrated juice is discharged from the bottom outlet, and ring-shaped ice crystals are removed from the top. The ice crystals obtained have an entrainment rate of 1.5%, which is 10% lower than that of single freeze-concentration. No crystal washing step is required, the concentration phase change time is shortened by 10%, and the concentration of vitamin C and other influencing factors in the concentrate is increased by 5%, 10% or more compared to single freeze-concentration and gas hydrate concentration, respectively.

[0058] Example 2

[0059] Pineapples at 80-90% ripeness are peeled and juiced to obtain pineapple juice with a solids content of 11°Brix. This juice is then pre-cooled to 3°C in a cold storage. A condensation circulation system is activated to ensure the temperature of the feed tank and the concentrator's interior matches the pre-cooled pineapple juice temperature. 4L of pre-cooled pineapple juice is pumped from the feed tank into the concentrator's interior, filling it to 2 / 5 of its volume. CO2 is introduced, and the stirring device is activated at 1000 rpm. Once the pressure reaches 4 MPa, the gas valve is closed. After a phase change is detected, the gas valve is opened to release the gas. Another 4L of pre-cooled pineapple juice is added, lowering the temperature of the concentrator's interior to -4°C. CO2 is continued until the pressure in the concentrator's interior reaches 3 MPa. The gas valve is then closed, and the stirring speed is increased to 2000 rpm. When the concentration of the concentrated juice in the concentrator's interior reaches 33°Brix, the concentrated juice is discharged from the bottom outlet, and ring-shaped ice crystals are removed from the top. The ice crystals obtained have an entrainment rate of 2.5%, which is 15% lower than that of single freeze-concentration. No crystal washing step is required, the concentration phase change time is shortened by 12%, and the protein and other components in the concentrate are increased by 8%, 12% or more compared to single freeze-concentration and gas hydrate concentration, respectively.

[0060] Example 3

[0061] Lychees at 80-90% ripeness are shelled, pulped, and juiced to obtain lychee juice with a solids content of 14°Brix. This juice is then pre-cooled to 0.5°C in a cold storage. A condensation circulation system is activated to ensure the temperature of the feed tank and the concentrator's interior matches the pre-cooled lychee juice temperature. 3L of pre-cooled lychee juice is pumped from the feed tank into the concentrator's interior, filling it to 3 / 10 of its volume. CO2 is introduced, and the stirring device is turned on at 1500 rpm. Once the pressure reaches 6 MPa, the gas valve is closed. After 20 minutes of processing, the gas valve is opened to release the gas. Another 4L of pre-cooled juice is added, lowering the temperature of the concentrator's interior to -6°C. CO2 is continued until the pressure in the concentrator's interior reaches 4 MPa. The gas valve is then closed, and the stirring speed is increased to 2500 rpm. When the concentration of the concentrated juice in the concentrator's interior reaches 35°Brix, the concentrated juice is discharged from the bottom outlet, and ring-shaped ice crystals are removed from the top. The ice crystals obtained have an entrainment rate of 2%, which is 14% lower than that of single freeze-concentration. No crystal washing step is required, the concentration phase change time is shortened by 14%, and the protein and other components in the concentrate are increased by 7%, 13% or more compared to single freeze-concentration and gas hydrate concentration, respectively.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A low-temperature concentration method for reducing crystal entrainment rate, characterized in that, Includes the following steps: S100. The liquid material is pre-cooled to control the temperature of the inner cavity of the concentration processor to be consistent with the pre-cooling temperature of the liquid material. S200: The pre-cooled liquid material is fed into the inner cavity of the concentration processor; S300. Introduce small molecule gas into the inner cavity of the concentration processor while stirring the liquid material, and adjust the pressure in the inner cavity of the concentration processor to a first pressure; the small molecule gas is at least one of the following: CO2, C2H4, CH4, N2; S400, Continue to convey the pre-cooled liquid material into the inner cavity of the concentration processor, and lower the temperature of the inner cavity of the concentration processor to -1~-12℃; S500, Continue to input small molecule gas into the inner cavity of the concentration processor, adjust the pressure in the inner cavity of the concentration processor to the second pressure, and increase the stirring speed, wherein the second pressure is lower than the first pressure; S600. When the liquid material in the inner cavity of the concentration processor reaches the target concentration, it is discharged from the inner cavity of the concentration processor, and all concentrated mother liquor is collected and the upper ring-shaped ice crystals are removed.

2. The low-temperature concentration method for reducing crystallization entrainment rate according to claim 1, characterized in that: In step S100, the liquid material is pre-cooled to a temperature of 0.5-8℃.

3. The low-temperature concentration method for reducing crystallization entrainment rate according to claim 2, characterized in that: In step S100, when the pre-cooled liquid material is fed into the inner cavity of the concentration processor, the volume of the liquid material is controlled to occupy 1 / 4-2 / 5 of the total volume of the inner cavity of the concentration processor; in step S400, the pre-cooled liquid material is continued to be fed into the inner cavity of the concentration processor, and the volume of the liquid material is controlled to occupy 1 / 2-4 / 5 of the total volume of the inner cavity of the concentration processor.

4. The low-temperature concentration method for reducing crystallization entrainment rate according to claim 3, characterized in that: In step S300, stirring is achieved by setting a stirrer in the inner cavity of the concentration processor, and the stirring speed of the stirrer is set to 500-1500 rpm; in step S500, small molecule gas is continued to be introduced during the cooling process, and the stirring speed of the stirrer is increased to 1500-2500 rpm.

5. The low-temperature concentration method for reducing crystallization entrainment rate according to claim 4, characterized in that: In step S300, the internal pressure of the concentration processor is adjusted to 3-10 MPa; in step S500, the internal pressure of the concentration processor is adjusted to 2-5 MPa.

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