Method for efficiently preparing fucoidin by taking kelp as raw material

Abstract

The invention relates to the technical field of natural polysaccharide extraction, and discloses a method for efficiently preparing fucoidin by taking kelp as a raw material, which comprises the following steps: S1, selecting fresh kelp and cleaning; s2, cutting and drying the cleaned kelp; s3, adopting freezing-unfreezing treatment to destroy the cell structure; s4, adding a nano material to enhance the extraction efficiency; s5, performing ultrasonic-assisted extraction by using deionized water; s6, obtaining fucoidin through the steps of centrifugal separation and membrane separation; and S7, performing freeze concentration and vacuum freeze drying to obtain a final product. Freezing-unfreezing treatment and ultrasonic-assisted extraction are combined, the extraction efficiency of fucoidin is remarkably improved, the defects of a traditional extraction method are overcome, meanwhile, food-grade modified nano materials are adopted for enhancing polysaccharide release, different components are effectively obtained through a multi-round extraction strategy, and higher extraction yield and diversified application potential are provided.

Description

Technical Field

[0001] The invention relates to the technical field of natural polysaccharide extraction, in particular to a method for efficiently preparing fucoidan using kelp as a raw material. Background Art

[0002] Fucoidan, as an important natural polysaccharide, is widely found in seaweed, especially brown algae, such as kelp and wakame. In recent years, with the increasing demand for health and natural ingredients, fucoidan has attracted widespread attention due to its unique biological activity and functionality. Studies have shown that fucoidan has a variety of biological activities, including antioxidant, anti-inflammatory, and immunomodulatory effects, which has continuously expanded its application potential in food, medicine, cosmetics, and biomedicine.

[0003] However, existing fucoidan extraction technologies still face many challenges. Traditional extraction methods, such as hot water extraction and organic solvent extraction, are often inefficient, the extraction process is long and requires high temperatures, and may lead to degradation of the target components. In addition, these methods may involve the use of chemical solvents that have potential risks to the environment and health, causing unnecessary environmental pollution and safety hazards.

[0004] In the context of the development of modern science and technology, how to improve the extraction efficiency of fucoidan, maintain its biological activity, and reduce its impact on the environment has become a hot topic in this field. Therefore, finding new extraction technologies, especially the ability to comprehensively utilize a variety of physical and chemical methods to improve extraction efficiency and quality, is an important direction of current fucoidan research. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for efficiently preparing fucoidan using kelp as raw material, which solves the problems of low efficiency and loss of active ingredients in traditional extraction technology.

[0006] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for efficiently preparing fucoidan using kelp as raw material, comprising the following steps:

[0007] S1. Select fresh kelp and wash it;

[0008] S2, cutting and drying the cleaned kelp;

[0009] S3, freeze-thaw treatment to destroy cell structure;

[0010] S4, adding nanomaterials to enhance extraction efficiency;

[0011] S5, ultrasonic-assisted extraction using deionized water;

[0012] S6, obtaining fucoidan through centrifugation and membrane separation steps;

[0013] S7, freeze concentration and vacuum freeze drying are performed to obtain the final product.

[0014] Preferably, in the S1 cleaning step, a 0.1M hydrochloric acid solution is used for soaking for 8-12 minutes, and then rinsed with deionized water for 2-3 times.

[0015] Preferably, in step S2, the kelp is cut into small pieces of 1-2 cm, and the drying temperature is 40° C.-60° C., and the drying temperature is dried to a moisture content of less than 10%.

[0016] Preferably, the step S3 specifically includes the following steps:

[0017] S3.1, Batch freezing: Put the processed kelp samples into sealed bags, set the freezing temperature to -15℃--20℃, keep it for 10-13h, and monitor that the center temperature of the sample is not lower than -18℃;

[0018] S3.2, Thawing: Thaw at room temperature for 2-2.5 hours, use slow thawing and rinse with warm water;

[0019] S3.3. Repeat treatment: Repeat the freeze-thaw cycle 3-5 times, observe the degree of cell structure disruption under a microscope, and record the effect.

[0020] Preferably, the step S4 specifically includes the following steps:

[0021] S4.1. Selection of nanomaterials: Use certified food-grade modified nanoclay or nanosilica;

[0022] S4.2, prepare suspension: mix the nanomaterial with deionized water at a concentration of 1-2%, use ultrasonic treatment, and control the temperature rise to no more than 60°C;

[0023] S4.3, mixing: mixing the prepared nanomaterial suspension with the frozen kelp, setting the stirring speed to 300-500 rpm for 25-35 min, and adding a surfactant with a concentration of 0.5-1% during the mixing process.

[0024] Preferably, the surfactant in step S4.3 is optionally one of sodium laurate, polyvinyl alcohol, sodium dihydrogen phosphate or hexadecyltrimethylammonium bromide.

[0025] Preferably, the step S5 specifically includes the following steps:

[0026] S5.1. Adding extraction solvent:

[0027] Solvent: deionized water, ratio 10:1;

[0028] S5.2, Ultrasonic assisted extraction: set the ultrasonic frequency to 20-40kHz, control the temperature at 30-50℃, and the time to 30-60min, and monitor the temperature during the process;

[0029] S5.3. Step extraction: perform two-step extraction.

[0030] Preferably, the distribution extraction in step S5.3 specifically includes the following steps:

[0031] First round of extraction: use deionized water to extract and collect the extract;

[0032] Second round of extraction: Use 0.1M dilute acid or dilute alkali for extraction, maintain the temperature at 30-40℃, and set the time to 25-35min.

[0033] Preferably, the step S6 specifically includes the following steps:

[0034] S6.1, centrifugal separation: use a high-speed centrifuge, set the speed to 3000-5000rpm, the time is 10-15min, and collect the upper liquid;

[0035] S6.2, Membrane separation: Use nanofiltration or ultrafiltration membrane, the membrane molecular weight cutoff range is set to 1-10kDa, the operating pressure is set to 0.1-0.5MPa, and the membrane is cleaned regularly using backwashing technology.

[0036] Preferably, the step S7 specifically includes the following steps:

[0037] S7.1. Freeze concentration: Freeze the extract to -75°C--80°C and keep for 4-6 hours;

[0038] S7.2, vacuum freeze drying: the cold trap temperature is set to -45℃--50℃, the vacuum degree is <0.1mbar, and the drying time is 24-48h;

[0039] S7.3. Gradual drying: Use spray drying technology with the inlet temperature set at 60-80°C and the outlet temperature controlled at 40-60°C to obtain granular fucoidan.

[0040] The present invention provides a highly efficient method for preparing fucoidan using kelp as raw material, which has the following beneficial effects:

[0041] 1. The present invention significantly improves the extraction efficiency of fucoidan by combining freeze-thaw treatment with ultrasonic-assisted extraction. The existing technology usually adopts a single hot water extraction or chemical solvent extraction method, which has low extraction efficiency and requires a long time of processing. The freeze-thaw cycle effectively destroys the kelp cell structure and promotes the release of polysaccharides, while the introduction of ultrasonic waves utilizes the vibration energy of sound waves to enhance the penetration of solvents into kelp cells, thereby improving the extraction efficiency.

[0042] 2. The food-grade modified nanomaterials used in the present invention, such as nanoclay or nanosilica, can enhance the interaction with the polysaccharides in kelp. The existing technology mostly uses traditional extractants, which lack the optimization of the interaction between substances. The high specific surface area and excellent dispersibility of nanomaterials enable them to more effectively promote the release of polysaccharides during the extraction process and improve the overall extraction effect.

[0043] 3. The present invention adopts a multi-round extraction strategy, using deionized water and dilute acid or dilute alkali respectively, which can fully extract different components of fucoidan. The existing technology often only uses a single extraction method, which makes it impossible to effectively extract certain polysaccharide components. Through step-by-step extraction, not only the overall extraction yield is improved, but also a variety of polysaccharides with different functions can be obtained, providing support for diversified applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Please refer to the attached Figure 1 The embodiment of the present invention provides a method for efficiently preparing fucoidan using kelp as raw material, comprising the following steps:

[0047] S1. Select fresh kelp and wash it;

[0048] S2, cutting and drying the cleaned kelp;

[0049] S3, freeze-thaw treatment to destroy cell structure;

[0050] S4, adding nanomaterials to enhance extraction efficiency;

[0051] S5, ultrasonic-assisted extraction using deionized water;

[0052] S6, obtaining fucoidan through centrifugation and membrane separation steps;

[0053] S7, freeze concentration and vacuum freeze drying are performed to obtain the final product.

[0054] In the S1 cleaning step, a 0.1M hydrochloric acid solution is used for soaking for 8-12 minutes, and then rinsed with deionized water 2-3 times.

[0055] In step S2, the kelp is cut into small pieces of 1-2 cm and dried at a temperature of 40° C. to 60° C. until the moisture content is less than 10%.

[0056] The S3 step specifically includes the following steps:

[0057] S3.1, Batch freezing: put the processed kelp samples into sealed bags, set the freezing temperature to -15℃--20℃, keep it for 10-13h, and monitor that the center temperature of the sample is not lower than -18℃;

[0058] S3.2, Thawing: Thaw at room temperature for 2-2.5 hours, use slow thawing and rinse with warm water;

[0059] S3.3. Repeat treatment: Repeat the freeze-thaw cycle 3-5 times, observe the degree of cell structure disruption under a microscope, and record the effect.

[0060] The S4 step specifically includes the following steps:

[0061] S4.1. Selection of nanomaterials: Use certified food-grade modified nanoclay or nanosilica;

[0062] S4.2, prepare suspension: mix the nanomaterial with deionized water at a concentration of 1-2%, use ultrasonic treatment, and control the temperature rise to no more than 60°C;

[0063] S4.3, mixing: mixing the prepared nanomaterial suspension with the frozen kelp, setting the stirring speed to 300-500 rpm for 25-35 min, and adding a surfactant with a concentration of 0.5-1% during the mixing process.

[0064] In step S4.3, the surfactant may be any one of sodium laurate, polyvinyl alcohol, sodium dihydrogen phosphate or hexadecyltrimethylammonium bromide.

[0065] Step S5 specifically includes the following steps:

[0066] S5.1. Adding extraction solvent:

[0067] Solvent: deionized water, ratio 10:1;

[0068] S5.2, Ultrasonic assisted extraction: set the ultrasonic frequency to 20-40kHz, control the temperature at 30-50℃, and the time to 30-60min, and monitor the temperature during the process;

[0069] S5.3. Step extraction: perform two-step extraction.

[0070] The distribution extraction in step S5.3 specifically includes the following steps:

[0071] First round of extraction: use deionized water to extract and collect the extract;

[0072] Second round of extraction: Use 0.1M dilute acid or dilute alkali for extraction, maintain the temperature at 30-40℃, and set the time to 25-35min.

[0073] Step S6 specifically includes the following steps:

[0074] S6.1, centrifugal separation: use a high-speed centrifuge, set the speed to 3000-5000rpm, the time is 10-15min, and collect the upper liquid;

[0075] S6.2, Membrane separation: Use nanofiltration or ultrafiltration membrane, the membrane molecular weight cutoff range is set to 1-10kDa, the operating pressure is set to 0.1-0.5MPa, and backwash technology is used for regular cleaning.

[0076] Step S7 specifically includes the following steps:

[0077] S7.1. Freeze concentration: Freeze the extract to -75°C--80°C and keep for 4-6 hours;

[0078] S7.2, vacuum freeze drying: the cold trap temperature is set to -45℃--50℃, the vacuum degree is <0.1mbar, and the drying time is 24-48h;

[0079] S7.3, graded drying: using spray drying technology, the inlet temperature is set at 60-80°C and the outlet temperature is controlled at 40-60°C to obtain granular fucoidan.

[0080] Embodiment 1

[0081] Embodiment description:

[0082] In this example, fresh kelp was used as raw material, and fucoidan was prepared according to the above technical scheme.

[0083] S1: Wash the kelp by soaking it in 0.1M hydrochloric acid solution for 10 minutes, and then rinse it with deionized water three times.

[0084] S2: Cut the kelp into small pieces of 1 cm, set the drying temperature at 50°C, and dry until the moisture content is less than 10%.

[0085] S3: freeze-thaw treatment, freezing temperature -18 °C, keep for 12 hours, thawing time 2 hours, repeated 3 times.

[0086] S4: Add 1% modified nanoclay to prepare a suspension, use ultrasonic treatment, control the temperature at 50°C, and treat for 15 minutes. Stir at 350 rpm for 30 minutes, and add 0.5% sodium laurate.

[0087] S5: Ultrasonic assisted extraction was performed using deionized water at a ratio of 10:1, the frequency was set at 30 kHz, and the extraction time was 40 min.

[0088] S6: centrifugal separation, rotation speed 4000 rpm, time 12 minutes, membrane separation using a membrane molecular weight cutoff range of 5 kDa, operating pressure 0.3 MPa.

[0089] S7: freeze concentration to -75°C, hold for 5 hours, vacuum freeze drying cold trap temperature -50°C, vacuum degree 0.05 mbar, drying time 36 hours, spray drying inlet temperature 70°C, outlet temperature 50°C.

[0090] Summarize:

[0091] This example effectively extracts fucoidan through basic steps and ensures that the parameters of each link meet the requirements to obtain a relatively ideal product.

[0092] Embodiment 2

[0093] Embodiment description:

[0094] Based on Example 1, the freeze-thaw treatment and ultrasonic extraction parameters were optimized.

[0095] S1: Wash the kelp by soaking it in 0.1M hydrochloric acid solution for 10 minutes, and then rinse it with deionized water three times.

[0096] S2: Cut the kelp into small pieces of 1-2 cm, set the drying temperature at 45°C, and dry until the moisture content is less than 8%.

[0097] S3: freeze-thaw treatment, freezing temperature -20°C, keeping for 13 hours, thawing time 2.5 hours, repeated 4 times.

[0098] S4: Add 1.5% nano-silica to prepare a suspension, use ultrasonic treatment, control the temperature at 55°C, treat for 20 minutes, stir at 400 rpm for 35 minutes, and add 0.75% polyvinyl alcohol.

[0099] S5: Ultrasonic assisted extraction was performed using deionized water in a ratio of 10:1, the frequency was set at 35 kHz, and the extraction time was 45 min.

[0100] S6: centrifugal separation, rotation speed 4500 rpm, time 12 minutes, membrane separation using a membrane molecular weight cutoff range of 3 kDa, operating pressure 0.4 MPa.

[0101] S7: freeze concentration to -80°C, hold for 5 hours, vacuum freeze drying cold trap temperature -45°C, vacuum degree 0.08 mbar, drying time 30 hours, spray drying inlet temperature 65°C, outlet temperature 45°C.

[0102] Summarize:

[0103] This embodiment further improves the extraction efficiency by optimizing the freezing treatment and ultrasonic extraction parameters.

[0104] Embodiment 3

[0105] Embodiment description:

[0106] Based on Example 2, the membrane separation and freeze concentration steps are improved.

[0107] S1: Clean the kelp by soaking it in 0.1M hydrochloric acid solution for 8 minutes, and then rinse it twice with deionized water.

[0108] S2: Cut the kelp into small pieces of 1-2 cm, set the drying temperature at 50°C, and dry until the moisture content is less than 9%.

[0109] S3: freeze-thaw treatment, freezing temperature -18 °C, maintained for 10 hours, thawing time 2 hours, repeated 5 times.

[0110] S4: Add 1% nano-silica to prepare a suspension, use ultrasonic treatment, control the temperature at 50°C, treat for 15 minutes, stir at 450 rpm for 30 minutes, and add 0.6% sodium dihydrogen phosphate.

[0111] S5: Ultrasonic assisted extraction was performed using deionized water in a ratio of 10:1, the frequency was set at 40 kHz, and the extraction time was 50 min.

[0112] S6: centrifugal separation, rotation speed 4000 rpm, time 10 minutes, membrane separation using a membrane molecular weight cutoff range of 2 kDa, operating pressure 0.5 MPa.

[0113] S7: freeze concentration to -75°C, hold for 6 hours, vacuum freeze drying cold trap temperature -50°C, vacuum degree 0.1 mbar, drying time 28 hours, spray drying inlet temperature 60°C, outlet temperature 40°C.

[0114] Summarize:

[0115] This embodiment improves the quality and purity of the extracted product by improving the membrane separation and freeze concentration steps.

[0116] Embodiment 4

[0117] Embodiment description:

[0118] On the basis of Example 3, a new surfactant and ultrasonic extraction technology were introduced.

[0119] S1: Wash the kelp by soaking it in 0.1M hydrochloric acid solution for 10 minutes, and then rinse it with deionized water three times.

[0120] S2: Cut the kelp into small pieces of 1-2 cm, set the drying temperature at 55°C, and dry until the moisture content is less than 7%.

[0121] S3: freeze-thaw treatment, freezing temperature -15°C, keep for 12 hours, thawing time 2 hours, repeated 4 times.

[0122] S4: Add 1.5% modified nanoclay to prepare a suspension, use ultrasonic treatment, control the temperature at 58°C, the treatment time is 18 minutes, the stirring speed is 500 rpm, and it lasts for 30 minutes, and add 0.8% hexadecyltrimethylammonium bromide.

[0123] S5: Ultrasonic assisted extraction was performed using deionized water at a ratio of 10:1, the frequency was set at 30 kHz, and the extraction time was 55 min.

[0124] S6: centrifugal separation, rotation speed 3500 rpm, time 10 minutes, membrane separation using a membrane molecular weight cutoff range of 1 kDa, operating pressure 0.4 MPa.

[0125] S7: freeze concentration to -80°C, hold for 6 hours, vacuum freeze drying cold trap temperature -45°C, vacuum degree 0.09 mbar, drying time 32 hours, spray drying inlet temperature 70°C, outlet temperature 50°C.

[0126] Summarize:

[0127] This example further improves the extraction efficiency and final product quality by introducing a new surfactant and optimizing the ultrasonic extraction conditions.

[0128] Embodiment 5

[0129] Embodiment description:

[0130] On the basis of Example 4, the overall extraction process was improved and an integrated design was performed.

[0131] S1: Clean the kelp by soaking it in 0.1M hydrochloric acid solution for 9 minutes, and then rinse it twice with deionized water.

[0132] S2: Cut the kelp into small pieces of 1-2 cm, set the drying temperature at 60°C, and dry until the moisture content is less than 5%.

[0133] S3: freeze-thaw treatment, freezing temperature -20°C, keeping for 13 hours, thawing time 2.5 hours, repeated 5 times.

[0134] S4: Add 2% nano-silica to prepare a suspension, use ultrasonic treatment, control the temperature at 55°C, treat for 20 minutes, stir at 550 rpm for 35 minutes, and add 0.9% polyvinyl alcohol.

[0135] S5: Ultrasonic assisted extraction was performed using deionized water in a ratio of 10:1, the frequency was set at 40 kHz, and the extraction time was 60 min.

[0136] S6: centrifugal separation, rotation speed 5000 rpm, time 12 minutes, membrane separation using a membrane molecular weight cutoff range of 1 kDa, operating pressure 0.3 MPa.

[0137] S7: freeze concentration to -75°C, hold for 4 hours, vacuum freeze drying cold trap temperature -50°C, vacuum degree 0.1 mbar, drying time 30 hours, spray drying inlet temperature 65°C, outlet temperature 45°C.

[0138] Summarize:

[0139] This embodiment significantly improves the extraction efficiency and yield of fucoidan through integrated design and comprehensive optimization of each step.

[0140] Summary:

[0141] The above five embodiments are interrelated and gradually deepened on the basis of embodiment 1. Each embodiment improves the extraction efficiency and product quality by optimizing parameters, introducing new materials and technical means while retaining the core steps. These embodiments demonstrate a variety of technical paths and provide rich practical basis for the efficient preparation of fucoidan using kelp as raw material.

[0142] Experimental design: Verify the effectiveness of the fucoidan preparation method of the present invention

[0143] Purpose:

[0144] The purpose of this experiment is to verify the superiority of the efficient preparation method of fucoidan of the present invention in terms of extraction efficiency, biological activity and product quality through systematic comparative experiments.

[0145] Experimental group division:

[0146] Control group: traditional hot water extraction method was used.

[0147] Experimental group A: freeze-thaw treatment combined with ultrasound-assisted extraction using deionized water.

[0148] Experimental group B: freeze-thaw treatment combined with ultrasound-assisted extraction using 0.1 M dilute acid.

[0149] Experimental group C: freeze-thaw treatment combined with ultrasound-assisted extraction using 0.1 M dilute alkali.

[0150] Materials preparation:

[0151] Fresh kelp: Choose kelp of the same type and batch, wash and cut into 1-2cm small pieces, and dry until the moisture content is less than 10%.

[0152] Nanomaterials: Food grade modified nanoclay and nanosilica were prepared to prepare a 1% suspension.

[0153] Extraction solvent: deionized water, 0.1M dilute acid, 0.1M dilute alkali.

[0154] Experimental steps:

[0155] Extraction process:

[0156] Control group:

[0157] The kelp sample was mixed with hot water at a ratio of 1:10, the temperature was set at 90°C, the extraction time was 120 minutes, and the upper liquid was collected by centrifugation (3000 rpm, 15 minutes).

[0158] Experimental groups A, B, and C:

[0159] Step 1: Freeze-thaw process

[0160] The treated kelp samples were frozen in batches, the temperature was set at -20°C, kept for 12 hours, and then thawed at room temperature for 2 hours. This process was repeated 3 times, and the changes in cell structure were observed during the process.

[0161] Step 2: Nanomaterial processing

[0162] Select suitable food-grade modified nanoclay or nanosilica, prepare a 1% suspension, and treat it with ultrasound (frequency of 30 kHz, treatment time of 10 minutes, temperature controlled below 60° C.) to ensure that the suspension is evenly dispersed.

[0163] Step 3: Extract

[0164] The freeze-thawed kelp was mixed with the prepared nanomaterial suspension in a ratio of 1:10 and extracted by ultrasonic assisted extraction (frequency of 30 kHz, time of 30 min, temperature set to 40°C), during which the temperature changes were monitored.

[0165] Step 4: Multiple rounds of extraction

[0166] The first round of extraction uses deionized water and collects the extract; the second round of extraction uses 0.1M dilute acid or dilute alkali, sets the temperature at 30-40°C, and the extraction time is 25-35 minutes.

[0167] Separation and purification

[0168] Centrifugation: The extract was centrifuged at high speed (5000 rpm, 10 minutes) and the supernatant was collected.

[0169] Membrane separation: Use nanofiltration membrane (molecular weight cutoff range 1-10 kDa), set the operating pressure to 0.2 MPa, and backwash regularly to maintain the permeability of the membrane.

[0170] Bioactivity and functionality testing

[0171] Antioxidant test: The antioxidant capacity of the extract was determined using the DPPH free radical scavenging method.

[0172] Antibacterial activity test: Standard strains (such as Escherichia coli and Staphylococcus aureus) were used to determine the diameter of the inhibition zone by the plate method.

[0173] Functional component analysis: The different polysaccharide components in the extracts were analyzed by high performance liquid chromatography (HPLC) to compare the purity and molecular weight distribution of the extracts.

[0174] Table 1:

[0175]

[0176]

[0177] Experimental summary:

[0178] By comparing the experimental results of different extraction methods, it is verified that the efficient preparation method of fucoidan of the present invention has significant advantages in extraction efficiency, biological activity and product quality. The specific analysis is as follows:

[0179] 1. Extraction efficiency: The extraction amount of experimental group A (using deionized water) was 9.8g, which was significantly higher than 5.2g of the control group, indicating that the combination of freeze-thaw treatment and ultrasonic-assisted extraction significantly improved the extraction efficiency of fucoidan. The extraction amounts of experimental groups B and C were 10.2g and 10.5g, respectively, which were also higher than the control group, further proving the effectiveness of the multi-round extraction strategy.

[0180] 2. Antioxidant activity: The antioxidant rate of experimental group A reached 75%, significantly higher than 45% of the control group. The antioxidant rates of experimental groups B and C were also 70% and 72%, respectively, indicating that the combination of freeze-thaw and ultrasonic extraction can better retain the bioactive components of polysaccharides, and the use of acid or alkali extraction has a positive effect on antioxidant activity.

[0181] 3. Antibacterial activity: The diameter of the inhibition zone of experimental group A was 12.0 mm, which was better than 8.5 mm of the control group. The antibacterial activities of experimental groups B and C were 11.5 mm and 11.8 mm, respectively, indicating that the extraction method not only increased the extraction amount of polysaccharides, but also enhanced their antibacterial activity, indicating its potential in food preservation and other applications.

[0182] 4. Purity: The purity of the extracts in the experimental groups was generally higher than that in the control group, with the purity of experimental group A being 90%, experimental group B being 88%, and experimental group C being 89%, while the purity of the control group was only 85%. This indicates that the preparation method of the present invention improves the purity of the product while ensuring the extraction efficiency, and has a good prospect for industrial application.

[0183] Further exploration and demonstration of experimental design:

[0184] Purpose:

[0185] The purpose of this experiment is to deeply explore the mechanism of the influence of different factors on the extraction efficiency, biological activity and product characteristics of fucoidan, so as to verify the effectiveness and applicability of the preparation method of the present invention.

[0186] Experimental design:

[0187] 1. Experimental group division:

[0188] Experimental group D: Explore the effect of different freezing temperatures on extraction efficiency (-10℃, -20℃, -30℃).

[0189] Experimental group E: Study the effect of ultrasonic frequency on the extraction effect (20kHz, 30kHz, 40kHz).

[0190] Experimental Group F: Evaluation of the effect of surfactant concentration on extraction efficiency and bioactivity (0.1%, 0.5%, 1.0%).

[0191] 2. Material preparation:

[0192] Use fresh kelp from the same batch to ensure consistent quality.

[0193] Prepare different concentrations of surfactant (such as sodium laurate).

[0194] The nanomaterials and extraction solvents were the same as in the previous experiments.

[0195] 3. Experimental steps:

[0196] 3.1 Experimental group D: Effect of freezing temperature

[0197] Step 1: Freezing

[0198] The kelp samples were frozen at -10℃, -20℃ and -30℃ respectively, each temperature was maintained for 12 hours, and the temperature changes were recorded.

[0199] Step 2: Thawing and Extraction

[0200] Thaw to room temperature, and extract using the previous ultrasonic extraction method (frequency 30 kHz, time 30 minutes, temperature 40°C).

[0201] Step 3: Data Logging

[0202] The extraction volume, antioxidant rate, antimicrobial activity and purity were recorded.

[0203] 3.2 Experimental Group E: Effect of Ultrasonic Frequency

[0204] Step 1: Ultrasonication

[0205] The nanomaterial suspension was treated using different ultrasonic frequencies (20kHz, 30kHz, 40kHz) while keeping other conditions unchanged.

[0206] Step 2: Extract

[0207] Follow the previous extraction steps and record the extraction volume and biological activity data.

[0208] Step 3: Data Logging

[0209] The extraction amount, antioxidant rate, antibacterial activity and purity of each group were recorded.

[0210] 3.3 Experimental Group F: Effect of Surfactant Concentration

[0211] Step 1: Surfactant treatment

[0212] Surfactants of different concentrations (0.1%, 0.5%, 1.0%) were prepared and mixed with the nanomaterial suspension.

[0213] Step 2: Extract

[0214] Standard extraction procedures were used and the extract yield and biological activity were recorded.

[0215] Step 3: Data Logging

[0216] The extraction volume, antioxidant rate, antimicrobial activity and purity were recorded.

[0217] 4. Data Recording and Analysis

[0218] The results of all experimental groups are organized into tables, see Tables 2-4, for comparative analysis.

[0219] Table 2. Experimental Group D: Effect of Freezing Temperature

[0220]

[0221] Table 3. Experimental Group E: Effect of Ultrasonic Frequency

[0222]

[0223]

[0224] Table 4. Experimental Group F: Effect of Surfactant Concentration

[0225]

[0226] Experimental summary:

[0227] By analyzing the results of each experimental group, the following conclusions can be drawn:

[0228] 1. Effect of freezing temperature: The lower freezing temperature (-30℃) significantly improved the extraction efficiency, antioxidant capacity and purity of fucoidan, indicating that extremely low temperature is conducive to the destruction of cell structure, thereby releasing more polysaccharides.

[0229] 2. Influence of ultrasonic frequency: The extraction effect is best at a frequency of 30kHz, which can effectively increase the extraction amount and biological activity, indicating that this frequency can optimize the penetration and destruction of sound waves on kelp cells.

[0230] 3. Effect of surfactant concentration: A surfactant concentration of 0.5% showed the best extraction effect, which could not only increase the extraction amount but also enhance the antioxidant property, showing that appropriate surfactant concentration can promote the extraction efficiency.

[0231] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly efficient method for preparing fucoidan using kelp as raw material, characterized in that: The following steps are involved: S1. Select fresh kelp and wash it; S2, cutting and drying the cleaned kelp; S3, freeze-thaw treatment to destroy cell structure; S4, adding nanomaterials to enhance extraction efficiency; S5, ultrasonic-assisted extraction using deionized water; S6, obtaining fucoidan through centrifugation and membrane separation steps; S7, freeze concentration and vacuum freeze drying are performed to obtain the final product.

2. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: In the S1 cleaning step, a 0.1M hydrochloric acid solution is used for soaking for 8-12 minutes, and then rinsed with deionized water for 2-3 times.

3. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: In the step S2, the kelp is cut into small pieces of 1-2 cm, and the drying temperature is 40° C.-60° C., and the drying temperature is dried to a moisture content of less than 10%.

4. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: The S3 step specifically includes the following steps: S3.1, Batch freezing: Put the processed kelp samples into sealed bags, set the freezing temperature to -15℃--20℃, keep it for 10-13h, and monitor that the center temperature of the sample is not lower than -18℃; S3.2, Thawing: Thaw at room temperature for 2-2.5 hours, use slow thawing and rinse with warm water; S3.

3. Repeat treatment: Repeat the freeze-thaw cycle 3-5 times, observe the degree of cell structure disruption under a microscope, and record the effect.

5. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: The S4 step specifically includes the following steps: S4.

1. Selection of nanomaterials: Use certified food-grade modified nanoclay or nanosilica; S4.2, prepare suspension: mix the nanomaterial with deionized water at a concentration of 1-2%, use ultrasonic treatment, and control the temperature rise to no more than 60°C; S4.3, mixing: mixing the prepared nanomaterial suspension with the frozen kelp, setting the stirring speed to 300-500 rpm for 25-35 min, and adding a surfactant with a concentration of 0.5-1% during the mixing process.

6. The method for efficiently preparing fucoidan using kelp as raw material according to claim 5, characterized in that: In the step S4.3, the surfactant is optionally one of sodium laurate, polyvinyl alcohol, sodium dihydrogen phosphate or hexadecyltrimethylammonium bromide.

7. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: The step S5 specifically includes the following steps: S5.

1. Adding extraction solvent: Solvent: deionized water, ratio 10:1; S5.2, Ultrasonic assisted extraction: set the ultrasonic frequency to 20-40kHz, control the temperature at 30-50℃, and the time to 30-60min, and monitor the temperature during the process; S5.

3. Step extraction: perform two-step extraction.

8. The method for efficiently preparing fucoidan using kelp as raw material according to claim 7, characterized in that: The stepwise extraction in step S5.3 specifically includes the following steps: First round of extraction: use deionized water to extract and collect the extract; Second round of extraction: Use 0.1M dilute acid or dilute alkali for extraction, maintain the temperature at 30-40℃, and set the time to 25-35min.

9. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: The step S6 specifically includes the following steps: S6.1, centrifugal separation: use a high-speed centrifuge, set the speed to 3000-5000rpm, the time is 10-15min, and collect the upper liquid; S6.2, Membrane separation: Use nanofiltration or ultrafiltration membrane, the membrane molecular weight cutoff range is set to 1-10kDa, the operating pressure is set to 0.1-0.5MPa, and the membrane is cleaned regularly using backwashing technology.

10. The method for efficiently preparing fucoidan using kelp as raw material according to claim 1, characterized in that: The step S7 specifically includes the following steps: S7.

1. Freeze concentration: Freeze the extract to -75°C--80°C and keep for 4-6 hours; S7.2, vacuum freeze drying: the cold trap temperature is set to -45℃--50℃, the vacuum degree is <0.1mbar, and the drying time is 24-48h; S7.3, graded drying: using spray drying technology, the inlet temperature is set at 60-80°C and the outlet temperature is controlled at 40-60°C to obtain granular fucoidan.

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