Probiotic freeze-dried powder and preparation method thereof

Abstract

The invention discloses probiotic freeze-dried powder and a preparation method of the probiotic freeze-dried powder, and the probiotic freeze-dried powder comprises the following raw materials in parts by weight: 1-10 parts of probiotics, 1-10 parts of probiotics and 1-10 parts of probiotics. The probiotic freeze-dried powder is prepared from the following raw materials in parts by weight: 100 to 300 parts of a compound probiotic agent, 30 to 50 parts of hydroxypropyl-beta-cyclodextrin, 20 to 40 parts of sodium alginate microspheres, 40 to 60 parts of galactooligosaccharide, 20 to 30 parts of resistant dextrin, 10 to 15 parts of cranberry concentrated juice, 5 to 10 parts of zinc gluconate, 3 to 8 parts of selenium-enriched yeast and 50 to 150 parts of a freeze-drying medium. According to the invention, the survival rate and the storage stability of thalli are remarkably improved through a composite strain compatibility-directional protective agent-low-temperature stepped freeze-drying synergistic technology; moreover, one-step elution is used for replacing multiple times of centrifugation, so that the energy consumption is obviously reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of freeze-dried powder, and in particular to a probiotic freeze-dried powder and a preparation method thereof. Background Art

[0002] Probiotic freeze-dried powder is a powdered product made by freeze-drying probiotics. This technology effectively maintains the activity and stability of probiotics, making them easier to store and transport. In today's society, where health awareness is increasing, freeze-dried probiotic powder has garnered widespread attention for its unique health benefits. Probiotics are a class of active microorganisms that are beneficial to the host, helping to maintain a balanced intestinal flora, promoting digestion and absorption, boosting immunity, and even potentially improving certain diseases. However, the activity of probiotics is easily affected by environmental factors such as temperature, humidity, and oxygen, making maintaining their activity during storage and transportation a significant challenge.

[0003] To address this issue, freeze-drying technology has emerged. This technique first rapidly freezes a probiotic solution, then converts the water content directly from solid to gaseous at low temperatures, achieving drying. This process is known as sublimation. This method maximizes the activity of the probiotics, as the low temperature and lack of oxygen minimize cell damage. With the deepening of scientific research and increasing consumer demand for health products, freeze-dried probiotic powder is becoming increasingly important in the market. It can not only be consumed directly as a health supplement, but can also be used as an additive in the production of food, beverages, and health products.

[0004] The existing probiotic freeze-dried powder technology has the following problems: (1) Low bacterial survival rate: Due to the single formula of protective agent or insufficient freeze-drying temperature control in traditional freeze-drying process, the bacteria are damaged during the dehydration process, and the viable bacterial rate is generally less than 60%.

[0005] (2) Poor stability: Conventional carriers (such as milk powder and chitosan oligosaccharides) have insufficient tolerance to acid / bile salts, resulting in a decrease in the colonization rate of probiotics in the gastrointestinal tract.

[0006] (3) Complex process: The purity is improved by multiple sludge washing, but the steps are cumbersome and energy-intensive, resulting in low industrial efficiency. Summary of the Invention

[0007] The problem to be solved by the present invention is to provide a probiotic freeze-dried powder and a preparation method thereof, which significantly improves the survival rate and storage stability of the bacteria through the synergistic technology of composite bacterial strain compatibility-directional protective agent-low-temperature step freeze-drying; and significantly reduces energy consumption by replacing multiple centrifugations with a one-step elution.

[0008] The present invention provides a technical solution for solving the above problems: a probiotic freeze-dried powder, wherein the raw materials of the probiotic freeze-dried powder include the following components in parts by weight: 100-300 parts of a composite probiotic agent, 30-50 parts of hydroxypropyl-β-cyclodextrin, 20-40 parts of sodium alginate microspheres, 40-60 parts of galacto-oligosaccharides, 20-30 parts of resistant dextrin, 10-15 parts of cranberry concentrated juice, 5-10 parts of zinc gluconate, 3-8 parts of selenium-enriched yeast, and 50-150 parts of a freeze-drying medium.

[0009] Preferably, the raw materials of the probiotic freeze-dried powder include the following components by weight: 100 parts of composite probiotics, 40 parts of hydroxypropyl-β-cyclodextrin, 20 parts of sodium alginate microspheres, 45 parts of galacto-oligosaccharides, 28 parts of resistant dextrin, 10 parts of cranberry concentrate, 8 parts of zinc gluconate, 6 parts of selenium-enriched yeast, and 80 parts of freeze-drying medium.

[0010] Preferably, the raw materials of the probiotic freeze-dried powder include the following components by weight: 250 parts of composite probiotics, 50 parts of hydroxypropyl-β-cyclodextrin, 30 parts of sodium alginate microspheres, 55 parts of galacto-oligosaccharides, 20 parts of resistant dextrin, 15 parts of cranberry concentrate, 10 parts of zinc gluconate, 3 parts of selenium-enriched yeast, and 100 parts of freeze-drying medium.

[0011] Preferably, the composite probiotic comprises Lactobacillus plantarum Lp90 (preservation number CGMCC 1.5578), Lactobacillus reuteri DSM17938, and Lactobacillus acidophilus LA85, with a weight ratio of 2:1:1.

[0012] Preferably, the freeze-drying medium is a pectin-calcium citrate gel network, wherein the weight ratio between pectin and calcium citrate is 5:1.

[0013] The present invention also discloses a method for preparing the probiotic freeze-dried powder as described in any one of the above, the preparation method comprising the following steps: Step 1. High-density fermentation Two-stage pH control fermentation: Seed liquid culture: pH 4.5-5.0, culture medium containing citrus fiber, soybean oligopeptides, and galacto-oligosaccharides; Main fermentation: pH 3.8-4.2, add broccoli juice and tomato juice, and terminate when OD600 reaches 8.0; Step 2. Directional treatment of bacterial sludge One-step elution method: the bacterial sludge and the elution solution were mixed at a ratio of 1:10, stirred at 300 rpm for 20 min, placed in a purification device for purification and impurity removal, and then centrifuged to a water content of 85%; Step 3. Low-temperature stepwise lyophilization Pre-freezing: -80℃ / 1h→-50℃ / 2h; Main drying: -40℃ / 10h→-25℃ / 5h; Desorption drying: 0℃ / 2h, the moisture content of the final product is ≤5%.

[0014] Preferably, the eluent in step 2 is a mixed solution of 2% glucose + 1% fucoidan + 0.3% glycerol.

[0015] Preferably, the pre-freezing in step 3 adopts gradient cooling with a cooling rate of 5°C / min.

[0016] Preferably, the main drying in step 3 is carried out under a vacuum environment with a vacuum degree of 0.1 mbar.

[0017] Preferably, the purification device in step 2 includes a purification barrel and several filter components, the purification barrel is provided with a filter chamber and a liquid collection chamber, the liquid collection chamber is provided at the lower end of the filter chamber, the filter chamber is provided with several filter cavities, and several of the filter components are detachably installed in the filter cavity.

[0018] Compared with the existing technology, the advantages of the present invention are: the present invention significantly improves the survival rate and storage stability of bacteria through the synergistic technology of composite bacterial strain compatibility-directional protective agent-low-temperature step freeze-drying; and, by replacing multiple centrifugations with one-step elution, energy consumption is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 It is a flowchart of the preparation method of the earth dragon compound protein powder of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the purification device of the present invention; Figure 3 is a cross-sectional view of a purification device of the present invention; Figure 4 yes Figure 3 A magnified schematic diagram of point A in the middle; Figure 5 yes Figure 3 A magnified schematic diagram of point B in the middle; Figure 6 It is a partial structural schematic diagram of the positioning release assembly of the purification device of the present invention; Figure 7 is a bottom view of the positioning release assembly of the purification device of the present invention; Figure 8 It is a partial structural schematic diagram of the installation pipe of the purification device of the present invention.

[0021] The attached drawings are marked with: 1. purification barrel, 2. mounting hole one, 3. filter chamber, 4. liquid inlet hole, 5. mounting tube, 6. hollow fiber filter tube, 7. switch baffle, 8. liquid collecting chamber, 9. filter chamber, 10. drive ring, 11. annular groove, 12. spring three, 13. positioning hole three, 14. movable rod, 15. positioning column one, 16. mounting groove one, 17. spring one, 18. matching groove one, 19. drive block one, 20. sealing ring, 21. mounting seat, 22. spring four, 23. positioning column three, 24. magnet block, 25. positioning column two, 26. spring two, 27. drive block two, 28. matching groove two, 29. positioning hole one, 30. docking tube, 31. docking chamber. DETAILED DESCRIPTION

[0022] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings and examples, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0023] In the description of the present invention, it should be noted that, for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and so on, indicating directions and positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Therefore, the terms "first" and "second" may explicitly or implicitly refer to one or more of these features. Throughout the description of the present invention, "several" means two or more, unless otherwise specifically defined.

[0025] In the present invention, unless otherwise specified or limited, the terms "assemble," "connect," and "connect" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integral connection; mechanical connection; direct connection, connection through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0026] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0027] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise. Example 1

[0028] This embodiment discloses a probiotic freeze-dried powder, characterized in that the raw materials of the probiotic freeze-dried powder include the following components, measured by weight: 100-300 parts of a composite probiotic agent, 30-50 parts of hydroxypropyl-β-cyclodextrin, 20-40 parts of sodium alginate microspheres, 40-60 parts of galacto-oligosaccharides, 20-30 parts of resistant dextrin, 10-15 parts of cranberry concentrate, 5-10 parts of zinc gluconate, 3-8 parts of selenium-enriched yeast, and 50-150 parts of a freeze-drying medium.

[0029] The composite probiotic comprises Lactobacillus plantarum Lp90 (preservation number CGMCC 1.5578), Lactobacillus reuteri DSM17938, and Lactobacillus acidophilus LA85, with a weight ratio of 2:1:1.

[0030] The freeze-drying medium is a pectin-calcium citrate gel network, wherein the weight ratio between pectin and calcium citrate is 5:1. Example 2

[0031] This embodiment discloses a ground dragon composite protein powder. The raw materials of the probiotic freeze-dried powder include the following components, measured by weight: 100 parts of a composite probiotic agent, 40 parts of hydroxypropyl-β-cyclodextrin, 20 parts of sodium alginate microspheres, 45 parts of galacto-oligosaccharides, 28 parts of resistant dextrin, 10 parts of cranberry concentrate, 8 parts of zinc gluconate, 6 parts of selenium-enriched yeast, and 80 parts of a freeze-drying medium. Example 3

[0032] This embodiment discloses a ground dragon composite protein powder. The raw materials of the probiotic freeze-dried powder include the following components, by weight: 250 parts of a composite probiotic agent, 50 parts of hydroxypropyl-β-cyclodextrin, 30 parts of sodium alginate microspheres, 55 parts of galacto-oligosaccharides, 20 parts of resistant dextrin, 15 parts of cranberry concentrate, 10 parts of zinc gluconate, 3 parts of selenium-enriched yeast, and 100 parts of a freeze-drying medium. Example 4

[0033] This embodiment discloses a method for preparing a probiotic freeze-dried powder, which comprises the following steps: Step 1. High-density fermentation Two-stage pH control fermentation: Seed liquid culture: pH 4.5-5.0, culture medium containing citrus fiber, soybean oligopeptides, and galacto-oligosaccharides; Main fermentation: pH 3.8-4.2, add broccoli juice and tomato juice, and terminate when OD600 reaches 8.0; Step 2. Directional treatment of bacterial sludge One-step elution method: the bacterial sludge and the elution solution were mixed at a ratio of 1:10, stirred at 300 rpm for 20 min, placed in a purification device for purification and impurity removal, and then centrifuged to a water content of 85%; Step 3. Low-temperature stepwise lyophilization Pre-freezing: -80℃ / 1h→-50℃ / 2h; Main drying: -40℃ / 10h→-25℃ / 5h; Desorption drying: 0℃ / 2h, the moisture content of the final product is ≤5%.

[0034] Wherein, the eluent in step 2 is a mixed solution of 2% glucose + 1% fucoidan + 0.3% glycerol.

[0035] Wherein, the pre-freezing in step 3 adopts gradient cooling, and the cooling rate is 5°C / min.

[0036] Wherein, the main drying in step 3 is carried out in a vacuum environment with a vacuum degree of 0.1 mbar.

[0037] Through the above solution, it is possible to achieve: High viable bacteria rate: compound protective agent + step freeze-drying makes the viable bacteria survival rate ≥90%; Long-lasting and stable: The bacterial release rate of the biphasic carrier in simulated gastric fluid is less than 10% within 2 hours, and the release rate in intestinal fluid is ≥80% within 2 hours; Process simplification: One-step elution replaces multiple centrifugations, reducing energy consumption by 40%.

[0038] In addition, this solution is the first to use a dual-phase carrier: dual protection through cyclodextrin encapsulation + sodium alginate sustained release to solve the problem of gastric acid tolerance; metabolic activation design: polyphenols and oligosaccharides in cranberry juice synergistically promote bacterial recovery; low-temperature directional drying: step-by-step temperature control to avoid ice crystals damaging the bacterial membrane structure. Example 5

[0039] like Figure 2-Figure 8As shown, this embodiment discloses a purification device, which is applied in Example 4. Specifically, the purification device includes a purification barrel 1 and several filter components. The purification barrel 1 is provided with a filter chamber 9 and a liquid collection chamber 8. The liquid collection chamber 8 is provided at the lower end of the filter chamber 9. The filter chamber 9 is provided with several filter cavities 3. Several of the filter components are detachably installed in the filter chamber 3.

[0040] The upper cover of the purification barrel 1 is provided with a plurality of mounting holes 2 for cooperating with the filter assembly, and the lower end of the filter chamber 9 is provided with a mounting hole 2 for cooperating with the filter assembly.

[0041] The filter assembly includes a mounting tube 5, a hollow fiber filter tube 6, a positioning assembly 1, a positioning assembly 2 and a positioning release assembly. The hollow fiber filter tube 6 is coaxially arranged inside the mounting tube 5. The positioning assembly 1 is arranged at the mounting hole 1 2 for positioning the upper part of the mounting tube 5. The positioning assembly 2 is arranged at the mounting hole 2 for positioning the lower part of the mounting tube 5. The positioning release assembly is arranged on the mounting tube 5 for releasing the positioning of the positioning assembly 1 and the positioning assembly 2.

[0042] Among them, a plurality of liquid inlet holes 4 are provided on the mounting tube 5, the positioning component 1 includes a spring 17 and a positioning column 15, and a mounting groove 16 is provided on the hole wall of the mounting hole 2, one end of the spring 17 is fixedly connected to the bottom of the mounting groove 16, and the other end is fixedly connected to the positioning column 15, the positioning column 15 extends out of the mounting groove 16 away from the end of the spring 17, and a positioning hole 29 is provided on the mounting tube 5 at a position corresponding to the mounting groove 16; the mounting component 2 includes a spring 26 and a positioning column 25, and a mounting groove 2 is provided on the hole wall of the mounting hole 2, one end of the spring 26 is fixedly connected to the bottom of the mounting groove 2, and the other end is fixedly connected to the positioning column 25, the positioning column 25 extends out of the mounting groove 2 away from the end of the spring 26, and a positioning hole 2 is provided on the mounting tube 5 at a position corresponding to the mounting groove 2; The positioning release assembly includes a drive ring 10, a plurality of movable rods 14 and a plurality of spring threes 12. The plurality of movable rods 14 are distributed in an annular array at the lower end of the drive ring 10. The upper end of the mounting tube 5 is provided with an annular groove 11 that cooperates with the drive ring 10. The spring three 12 is arranged in the annular groove 11 and one end is fixedly connected to the bottom of the annular groove 11, and the other end is fixedly connected to the bottom of the drive ring 10. A movable hole that cooperates with the movable rod 14 is provided in the mounting tube 5. The upper and lower ends of the movable rod 14 are respectively provided with a drive block 19 and a drive block 27. A matching groove 18 that cooperates with the drive block 19 and a matching groove 12 that cooperates with the drive block 19 are provided in the mounting tube 5. The driving block 27 cooperates with the matching groove 28, and the matching groove 18 is connected with the positioning hole 1 29, and the matching groove 28 is connected with the positioning hole 2. When the driving ring 10 is pressed downward, the driving ring 10 drives the movable rod 14 to move downward, and then drives the driving block 19 and the driving block 2 27 to move downward. In the process of the driving block 19 moving downward, the positioning column 15 is squeezed so that the positioning column 15 retracts into the installation groove 1 16. In the process of the driving block 2 27 moving downward, the positioning column 2 25 is squeezed so that the positioning column 2 25 retracts into the installation groove 2, thereby releasing the positioning component 1 and the positioning component 2 from the positioning of the mounting tube 5.

[0043] A docking cavity 31 is provided at the upper end of the mounting tube 5, and a docking tube 30 which is adapted to the shape of the docking cavity 31 is provided at the lower end of the mounting tube 5. A plurality of positioning holes three 13 are provided on the cavity wall of the docking cavity 31, and a plurality of mounting seats 21 are provided on the docking tube 30. A mounting groove three is provided in the mounting seat 21, and a spring four 22 and a positioning column three 23 are provided in the mounting groove three. One end of the spring four 22 is fixedly connected to the groove bottom of the mounting groove, and the other end is fixedly connected to the positioning column three 23. When the two filter components are docked up and down, the positioning column of the docking tube 30 of the upper filter component is inserted into the positioning hole three 13 in the docking cavity 31 of the lower filter component, and the positioning column three 23 is made of magnets. A plurality of magnet blocks 24 are provided at the mounting hole two, and the magnet blocks 24 are arranged to repel the positioning column three 23, and a sealing ring 20 is provided in both the mounting hole one 2 and the mounting hole two.

[0044] In the above scheme, when replacing the filter assembly, align the docking tube at the lower end of the new filter assembly with the filter assembly to be replaced, and insert the docking tube into the docking cavity of the old filter assembly. During the insertion process, the new filter assembly drives the driving ring to press downward, and the movable rod follows the driving ring to press downward, and then the driving block 1 and the driving block 2 on the movable rod both move downward. During the downward movement of the driving block 1, the positioning post 1 is squeezed to make the positioning post 1 retract into the inside of the installation groove 1. During the downward movement of the driving block 2, the positioning post 2 is squeezed to make the positioning post 2 retract into the inside of the installation groove 2. The positioning of the mounting tube 5 by the positioning assembly 1 and the positioning assembly 2 is released. At the same time, the positioning post of the docking tube 30 of the new filter assembly is inserted into the positioning hole 3 13 in the docking cavity 31 of the old filter assembly, and the new filter assembly is aligned with the old filter assembly. Then position it, and then continue to press the new filter assembly downward until the position of the positioning post three corresponds to the position of the magnet block in the mounting hole two. At this time, the magnet block generates a repulsive force on the positioning post three to press the positioning post back into the mounting groove three, and the old filter assembly falls into the liquid collection chamber under the action of its own gravity. At the same time, the positioning post one in the positioning assembly one is inserted into the positioning hole one on the mounting tube of the new filter assembly, and the positioning post two in the positioning assembly two is inserted into the positioning hole two on the mounting tube of the new filter assembly, and the positioning assembly is installed. Through the above scheme, when the old filter assembly needs to be replaced, the filter assembly can be quickly replaced through the above structure, and there is no need to disassemble the purification barrel for replacement, which improves the replacement efficiency. At the same time, during the replacement process, the purification and filtration work can continue, effectively ensuring the filtration efficiency.

[0045] It should be noted that an openable and closable switch baffle 7 is provided in the liquid collecting chamber, and the installation tube 5 dropped into the liquid collecting chamber can be taken out by opening the switch baffle 7 .

[0046] In this embodiment, it should be noted that the purification barrel of this device is made of transparent material. When the filtering effect of the filter component in a certain filter cavity is reduced, its filtering capacity is reduced, and the liquid passing through the hollow fiber filter tube becomes less. Therefore, the staff can observe through the transparent purification barrel that the liquid level in the filter cavity is significantly higher than the liquid levels of the other filter cavities, and can replace the filter component in the corresponding filter cavity.

[0047] The above description is merely a description of the preferred embodiment of the present invention and is not to be construed as limiting the scope of the claims. The present invention is not limited to the above embodiment, and variations in the specific structure are permitted. Any variations within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

Claims

1. A probiotic freeze-dried powder, characterized in that: The raw materials of the probiotic freeze-dried powder include the following components by weight: 100-300 parts of a composite probiotic agent, 30-50 parts of hydroxypropyl-β-cyclodextrin, 20-40 parts of sodium alginate microspheres, 40-60 parts of galacto-oligosaccharides, 20-30 parts of resistant dextrin, 10-15 parts of cranberry concentrated juice, 5-10 parts of zinc gluconate, 3-8 parts of selenium-enriched yeast, and 50-150 parts of a freeze-drying medium.

2. A probiotic freeze-dried powder according to claim 1, characterized in that: The raw materials of the probiotic freeze-dried powder include the following components by weight: 100 parts of a composite probiotic agent, 40 parts of hydroxypropyl-β-cyclodextrin, 20 parts of sodium alginate microspheres, 45 parts of galacto-oligosaccharides, 28 parts of resistant dextrin, 10 parts of cranberry concentrated juice, 8 parts of zinc gluconate, 6 parts of selenium-enriched yeast, and 80 parts of a freeze-drying medium.

3. The probiotic freeze-dried powder according to claim 1, characterized in that: The raw materials of the probiotic freeze-dried powder include the following components by weight: 250 parts of composite probiotics, 50 parts of hydroxypropyl-β-cyclodextrin, 30 parts of sodium alginate microspheres, 55 parts of galacto-oligosaccharides, 20 parts of resistant dextrin, 15 parts of cranberry concentrated juice, 10 parts of zinc gluconate, 3 parts of selenium-enriched yeast, and 100 parts of freeze-drying medium.

4. The probiotic freeze-dried powder according to claim 1, characterized in that: The composite probiotic comprises Lactobacillus plantarum Lp90 (preservation number CGMCC 1.5578), Lactobacillus reuteri DSM17938, and Lactobacillus acidophilus LA85, with a weight ratio of 2:1:

1.

5. The probiotic freeze-dried powder according to claim 1, characterized in that: The freeze-drying medium is a pectin-calcium citrate gel network, wherein the weight ratio between pectin and calcium citrate is 5:

1.

6. A method for preparing the freeze-dried probiotic powder according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Step 1. High-density fermentation Two-stage pH control fermentation: Seed liquid culture: pH 4.5-5.0, culture medium containing citrus fiber, soybean oligopeptides, and galacto-oligosaccharides; Main fermentation: pH 3.8-4.2, add broccoli juice and tomato juice, and terminate when OD600 reaches 8.0; Step 2. Directional treatment of bacterial sludge One-step elution method: the bacterial sludge and the elution solution were mixed at a ratio of 1:10, stirred at 300 rpm for 20 min, placed in a purification device for purification and impurity removal, and then centrifuged to a water content of 85%; Step 3. Low-temperature stepwise lyophilization Pre-freezing: -80℃ / 1h→-50℃ / 2h; Main drying: -40℃ / 10h→-25℃ / 5h; Desorption drying: 0℃ / 2h, the moisture content of the final product is ≤5%.

7. The method for preparing the freeze-dried probiotic powder according to claim 6, wherein: The eluent in step 2 is a mixed solution of 2% glucose + 1% fucoidan + 0.3% glycerol.

8. The method for preparing the freeze-dried probiotic powder according to claim 6, wherein: In step 3, the pre-freezing is performed by gradient cooling at a cooling rate of 5°C / min.

9. The method for preparing the freeze-dried probiotic powder according to claim 6, wherein: The main drying in step 3 is carried out under vacuum with a vacuum degree of 0.1 mbar.

10. The method for preparing the freeze-dried probiotic powder according to claim 6, wherein: The purification device in step 2 includes a purification barrel and several filter components. The purification barrel is provided with a filter chamber and a liquid collection chamber. The liquid collection chamber is provided at the lower end of the filter chamber. The filter chamber is provided with several filter cavities. Several filter components are detachably installed in the filter chamber.

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