Organic selenium-rich biological nutritional agent and preparation method thereof

Abstract

The invention relates to the field of functional food and nutritional supplements.The nutritional agent comprises a selenium source, a ligand, a carrier stabilizer, an antioxidant and auxiliary materials, the complexing efficiency is improved through the multi-point coordination design of the complex ligand and the selenium source, the particle size is controlled to range from 100 nm to 200 nm through a nanocrystallization dispersion technology, and the organic selenium-rich biological nutritional agent is prepared. Chitosan and an antioxidant synergistically protect a complex, the stability and oxidation resistance of the complex are remarkably improved, and meanwhile targeted controlled release is achieved through a coating structure of chitosan and sodium alginate. The preparation method comprises the steps of ligand solution pretreatment, selenium complex reaction, nanocrystallization dispersion, stabilization treatment, spray drying and the like. The complex efficiency, stability and bioavailability of selenium are improved, and the selenium complex has wide application value.

Description

Technical Field

[0001] The present invention relates to the technical field of functional foods and nutritional supplements, and specifically to an organic selenium-rich biological nutrient and a method for preparing the same. Background Art

[0002] Selenium is an essential trace element for the human body. In recent years, it has received extensive attention due to its significant physiological functions in antioxidant, immune regulation, and anti-cancer aspects. However, the intake of selenium needs to be appropriate. Excessive or long-term intake of inorganic selenium (such as selenite or selenate) may cause selenium poisoning, manifested as liver and kidney damage and nervous system abnormalities. Therefore, organic selenium has become the main direction for the research and development of selenium supplements due to its high bioavailability and low toxicity. On this basis, further realizing the development of safe and efficient selenium nutritional supplements by improving the stability of organic selenium, enhancing the bioavailability, and regulating the release performance has become the key point of technological development in this field.

[0003] In the prior art, organic selenium preparations mainly focus on selenocysteine, selenomethionine, and selenium yeast. Selenocysteine has high biological activity because its structure is consistent with the active center of selenium proteins in the human body. However, in complex storage or use environments, selenocysteine is prone to oxidation or degradation caused by changes in external pH, temperature, etc., resulting in insufficient product stability. At the same time, unprotected selenocysteine may be prematurely released or degraded in the gastrointestinal tract, unable to achieve targeted release, which limits the exertion of its nutritional value. Some studies have introduced ligands (such as sulfur-containing amino acids) to complex with selenium, but the complexation of a single ligand with selenium is limited, and problems such as low complexation efficiency and insufficient stability of the complex are prone to occur.

[0004] In addition, to improve the stability and functionality of the preparation, chitosan, gelatin, etc. are often introduced as stabilizers in the prior art. However, the molecular weight and dispersity of chitosan have a significant impact on the performance of the complex. High molecular weight chitosan has a strong protective effect, but due to its high viscosity, it often leads to uneven distribution of the complex, affecting the absorption effect. While low molecular weight chitosan has limited protective effect and insufficient antioxidant ability, making it difficult to meet the storage and release requirements under complex conditions. At the same time, the synergistic design of the stabilizer and the selenium complex is not yet perfect, lacking a solution for the integration of stabilization and controlled release.

[0005] As an effective means to improve the bioavailability of selenium complexes, nano-dispersion technology has been gradually applied to the preparation of selenium supplements in recent years. By reducing the particle size and increasing the specific surface area of the complex, it can indeed improve its solubility and absorption efficiency to a certain extent. However, the dispersion process of some existing processes fails to achieve particle homogenization, easily leading to problems such as uneven particle size distribution, particle aggregation, and unstable release. In addition, the dispersion technology mainly relies on a single process (such as high-speed shearing or simple spray drying), lacking strategies for process optimization and multi-step combination, and it is difficult to form highly efficient and stable nano-structured complexes.

[0006] Antioxidant performance is a key factor affecting the stability of selenium complexes. In existing technologies, a single antioxidant (such as vitamin C) is mostly used to protect selenium complexes, but the effect of a single antioxidant is limited and cannot effectively cope with multiple oxidative stresses in storage or complex physiological environments. In addition, the addition of antioxidants mostly does not form a synergistic effect with selenium complexes, and the protection effect is not significant enough, affecting the stability and functionality of the product.

[0007] Therefore, the present invention proposes a bio-nutrient rich in organic selenium and its preparation method to solve the problems of low complexation efficiency, poor stability, insufficient bioavailability, and poor controlled release performance of existing selenium supplements. Summary of the Invention

[0008] Aiming at the problems of low complexation efficiency, poor stability, insufficient bioavailability, and poor controlled release performance of selenium supplements in the prior art, the present invention provides a bio-nutrient rich in organic selenium and its preparation method. By optimizing the selenium source, ligand type and ratio, and combining the dispersion process and stabilization treatment, a selenium-rich preparation with high efficiency, stability, and excellent controlled release performance is developed.

[0009] To achieve the above objectives, the present invention is realized through the following technical solutions: A bio-nutrient rich in organic selenium, the bio-nutrient contains the following components, calculated by weight percentage: Selenium source: 0.02% - 0.1%; The selenium in selenocysteine exists in a bonded form. Under the action of the ligand, it can combine with the functional groups (such as mercapto group, amino group) of sulfur-containing amino acids and glutathione through coordination bonds to form a complex, thus effectively avoiding the oxidation and toxicity problems caused by free selenium.

[0010] Ligand: 0.15% - 0.8%, the ligand includes at least one of sulfur-containing amino acids and glutathione; The selection of the ligand is based on the HSAB (Hard and Soft Acids and Bases theory) and the principles of coordination chemistry. Selenium is a soft acid, and ligands with mercapto groups (soft basicity) and amino groups (neutral basicity) are preferably used as coordination groups. A stable selenium complex can be formed through the strong coordination between the mercapto group and selenium. This complexation can effectively protect the activity of selenium, prevent its oxidation or conversion into inorganic selenium, thereby improving stability and bioavailability.

[0011] Carrier stabilizer: 1% - 10%, and the carrier stabilizer is chitosan or its derivatives; Chitosan can form an electroprotective layer with the selenium complex through its cationic properties, preventing the decomposition of the complex. In addition, the selection of the molecular weight range of chitosan ensures that it not only has strong coating ability but also can gradually release the selenium complex in the intestine, thereby playing a role in controlled release and stabilization.

[0012] Antioxidant: 0.02% - 0.1%, and the antioxidant includes at least one or two of vitamin C and β-carotene; The antioxidant prevents the oxidative degradation of the selenium complex during preparation and storage by capturing free radicals. The high water solubility and reducibility of vitamin C enable it to effectively protect the complex structure of selenium, while the lipophilic property of β-carotene can enhance the antioxidant ability of the finished product in a composite environment.

[0013] Excipients: 60% - 80%, and the excipients include at least two of maltodextrin and sodium alginate.

[0014] As a carrier substance, the excipients can evenly disperse the complex, improving the processing performance and taste of the product. The high viscosity of sodium alginate helps to protect and form the complex, while the shaping ability of maltodextrin enhances the fluidity and solubility of the product. The combination of the two can significantly improve the stability and usability of the nutrient.

[0015] Preferably, the selenium source is selenocysteine.

[0016] Preferably, the ligand is a combination of cysteine and glutathione, and the weight ratio of the two is 1:1 - 1:3.

[0017] Preferably, the carrier stabilizer is chitosan, and the molecular weight of chitosan is 10 - 50 kDa.

[0018] Preferably, the excipients are a combination of maltodextrin and sodium alginate, and the weight ratio of maltodextrin to sodium alginate is 3:1 - 5:1.

[0019] Preferably, a method for preparing a selenium-rich organic selenium biological nutrient includes the following steps: S1. Pretreatment of the ligand solution: Dissolve the ligand in deionized water, adjust the pH to 7.0 - 7.5, and stir for 15 - 30 minutes; Under neutral to weakly alkaline conditions, the mercapto group (-SH) and amino group (-NH2) in the ligand can be fully exposed, enhancing their coordination activity while avoiding the oxidation of the mercapto group to form disulfide bonds, thus providing an optimal active environment for the selenium complexation reaction.

[0020] S2. Selenium complexation reaction: Slowly add the selenium source solution dropwise to the ligand solution and react for 60 - 120 minutes under the conditions of 35 - 40 °C and a stirring speed of 300 - 500 rpm. During the slow dropwise addition, selenocysteine gradually contacts the ligand and forms an organic selenium complex through the complexation reaction. The reaction temperature is controlled at 35 - 40 °C, which not only avoids selenium oxidation but also provides the necessary activation energy for the complexation reaction, enabling the complexation rate to reach the optimum.

[0021] S3. Nanonization dispersion: Perform high - speed shear dispersion on the complexation reaction solution at a dispersion speed of 8,000 - 12,000 rpm for 10 - 15 minutes. High - speed shear dispersion can significantly reduce the particle size of the complex, bringing it to the nanoscale range of 100 - 200 nm, thereby increasing its specific surface area, improving water solubility and bioavailability. The nanonized complex is more easily absorbed through the intestinal mucosa, enhancing the effect of the nutritional agent.

[0022] S4. Stabilization treatment: Add the chitosan stabilizer solution, and after mixing evenly, adjust the pH to 5.5 - 6.0. Chitosan carries a positive charge under weakly acidic conditions and can coat the negatively charged selenium complex through electrostatic interaction to form a protective layer, thus preventing the dissociation of the complex. At the same time, the concentration range of the chitosan solution (1% - 3%) and the mixing time (30 - 60 minutes) can ensure the uniformity and integrity of the coating.

[0023] S5. Drying into finished product: Prepare the powder by spray drying, with the inlet temperature of spray drying being 150 - 180 °C and the outlet temperature being 75 - 85 °C.

[0024] Spray drying can quickly remove the solvent and form a stable powder product. Through precise control of the temperature range, thermal degradation of the selenium complex is avoided, and at the same time, the powder has good fluidity and particle uniformity.

[0025] Preferably, the concentration of the ligand solution is 1% - 3% (w / v).

[0026] This concentration range can provide sufficient complexing groups while avoiding ligand aggregation or precipitation caused by too high a concentration.

[0027] Preferably, in the selenium complexation reaction, the dropping rate of the selenium source solution is 0.5 - 1 mL / min.

[0028] Too fast a droplet acceleration may lead to local uneven reaction, while too slow a droplet acceleration may reduce production efficiency. This range can achieve a balance between reaction uniformity and efficiency.

[0029] Preferably, the particle size of the complex after high-speed shear dispersion is 100 to 200 nm.

[0030] Nano-scale particle size can significantly improve bioavailability while ensuring the dispersibility and solubility of the formulation. Nano-scale particle size can significantly improve bioavailability while ensuring the dispersibility and solubility of the formulation.

[0031] Preferably, the concentration of the chitosan solution in the stabilization treatment step is 1% to 3% (w / v), and the mixing time is 30 to 60 minutes.

[0032] This concentration and time range ensures that chitosan forms a uniform coating structure, which not only avoids excessive viscosity affecting the process, but also ensures the stability of the complex.

[0033] The present invention provides a biological nutrient rich in organic selenium and a preparation method thereof. It has the following beneficial effects: 1. The present invention adopts a composite ligand technology scheme of selenocysteine, sulfur-containing amino acids and glutathione. By adjusting the ligand ratio and complexation conditions, it ensures the full combination of selenium and functional groups to form a highly stable organic selenium complex. This multi-point coordination strategy significantly improves the complexation efficiency and the antioxidant properties of the complex. Compared with the prior art scheme of using a single ligand (such as cysteine) or directly using inorganic selenium, it overcomes the problems of easy degradation and oxidation of selenium during storage and use, while effectively avoiding the defects of toxicity and low utilization rate of inorganic selenium, achieving a safer and more efficient way of selenium supplementation.

[0034] 2. The present invention introduces chitosan as a carrier stabilizer, combines its cationic properties and precise control of molecular weight, constructs a multi-layer protective barrier for the complex, and at the same time gives the nutrient agent good controlled release performance. Chitosan forms a protective colloid in the gastric acid environment and gradually releases the selenium complex in the alkaline environment of the small intestine to ensure its full absorption in the target area. Compared with the prior art solutions that rely on antioxidants for protection alone or do not use stabilizers, the present invention effectively solves the instability of selenium complexes under complex physiological conditions, reduces the risk of selenium loss, and improves the bioavailability and storage stability of the product.

[0035] 3. The present invention adopts nano-dispersion technology, and controls the particle size of the selenium complex within the nanometer range of 100 to 200 nm through high-speed shear dispersion and high-pressure homogenization treatment, which significantly improves the specific surface area and solubility of the selenium complex. This optimized nano-process enables the complex to be more evenly distributed in the aqueous medium, and is more easily absorbed by the intestinal mucosa, significantly improving its bioavailability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of the manufacturing method of the selenium-rich organic selenium biological nutrient agent. Specific implementation manners

[0037] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0038] Please refer to the attached Figure 1 : Example 1: Pretreatment of the ligand solution: Weigh 0.5 g of cysteine and 1.0 g of glutathione, dissolve them in 100 mL of deionized water, adjust the pH to 7.2, and stir for 20 minutes to form a ligand solution. The solution is kept in an environment of 25 °C for standby.

[0039] Selenium complexation reaction: Prepare a 0.05% (w / v) selenocysteine solution, and slowly drop the selenium solution into the ligand solution at a rate of 0.8 mL / min. Under the constant temperature condition of 35 °C, stir and react for 90 minutes, and set the stirring speed to 400 rpm. After the reaction, a light yellow complex solution is obtained.

[0040] Nanometer dispersion: Use a high-speed shear disperser to process the complex solution, set the rotation speed to 10,000 rpm, and control the time within 12 minutes. After dispersion, the particle size of the complex is detected by the dynamic light scattering method, and the particle size is 150 nm.

[0041] Stabilization treatment: Prepare a 2% (w / v) chitosan solution, and adjust the pH to 6.0 with 0.1 M acetic acid. Mix the dispersed complex solution and the chitosan solution according to a volume ratio of 2:1, stir evenly, and control the time within 40 minutes.

[0042] Drying to obtain the finished product: Use a spray dryer, set the inlet temperature to 165 °C, the outlet temperature to 80 °C, and the inlet flow rate to 1 mL / min. After drying, a uniform powdery selenium-rich organic selenium biological nutrient agent is obtained.

[0043] Example 2: Preparation of the ligand solution: Dissolve 1.5 g of cysteine in 200 mL of deionized water, adjust the pH of the solution to 7.0, and stir for 25 minutes. Keep the solution temperature at 30 °C for standby.

[0044] Selenium complexation reaction: Prepare a 0.1% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.5 mL / min. Control the reaction temperature at 40 °C and the stirring speed at 500 rpm. The continuous reaction time is 75 minutes to obtain a homogeneous complex solution.

[0045] Nanometerization treatment: Use a high-pressure homogenizer for treatment, twice: Set the first homogenization pressure at 60 MPa for preliminary particle fragmentation; Set the second homogenization pressure at 80 MPa to further homogenize the particle size and distribution.

[0046] After homogenization, use dynamic light scattering (DLS) to detect the particle size. The results show that: The D50 value is 120 nm, that is, 50% of the particle size is less than or equal to 120 nm; The D10 value is 92 nm and the D90 value is 148 nm, indicating that the particle size distribution range is relatively narrow and the particle size is relatively uniform.

[0047] Chitosan stabilization: Prepare a 1.5% (w / v) chitosan solution, adjust the pH to 5.8, add it to the complex solution at a volume ratio of 1:1, stir evenly, and the mixing time is 50 minutes.

[0048] Spray drying: Spray dry the stabilized liquid, set the feed temperature at 150 °C and the outlet temperature at 75 °C to obtain a powder product with uniform particles and a moisture content of less than 5%.

[0049] Example 3: Ligand and antioxidant pretreatment: Dissolve 1.0 g of cysteine, 2.0 g of glutathione and 0.2 g of vitamin C in 150 mL of deionized water, adjust the pH to 7.3, and stir for 20 minutes.

[0050] Selenium complexation reaction: Prepare a 0.03% (w / v) selenocysteine solution, control the dropping rate at 1 mL / min, drop it into the ligand solution, the stirring speed is 350 rpm, the reaction temperature is 35 °C, and the continuous reaction time is 120 minutes.

[0051] High-speed shear dispersion: Place the complex solution in a high-speed shear disperser for treatment, set the dispersion speed at 12,000 rpm, and the dispersion time at 15 minutes. After dispersion, the detected particle size is 140 nm.

[0052] Stabilization treatment: Prepare a 3% (w / v) chitosan solution and add it to the complexing solution at a volume ratio of 1.5:1. Mix and stir for 30 minutes, and adjust the pH to 6.0 to obtain a stable complex solution.

[0053] Spray drying: Use spray drying equipment with an inlet temperature of 170 °C and an outlet temperature of 80 °C to obtain a powder of selenium-rich bio-nutrient agent after drying, with uniform particles and strong antioxidant properties.

[0054] Example 4 Preparation of ligand solution: Dissolve 2.0 g of glutathione in 100 mL of deionized water, adjust the pH to 7.5, stir for 30 minutes, and keep the solution at 25 °C for standby.

[0055] Selenium complexation reaction: Prepare a 0.02% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.7 mL / min. Stir at a speed of 400 rpm, react at a temperature of 37 °C for 90 minutes to obtain a complexing solution.

[0056] Nanometerization treatment Process the complexing solution through a high-pressure homogenizer in two steps: Set the first homogenization pressure to 70 MPa to initially break the particles; Set the second homogenization pressure to 100 MPa to further homogenize the particle size and distribution.

[0057] After homogenization, use dynamic light scattering (DLS) to detect the particle size. The results show that: The D50 value is 110 nm, indicating that 50% of the particle sizes are less than or equal to 110 nm; The D10 value is 90 nm and the D90 value is 135 nm, indicating that the particle distribution is uniform and the particle size range is narrow.

[0058] Stabilization treatment with chitosan and sodium alginate: Prepare a 2% (w / v) chitosan solution and a 1% (w / v) sodium alginate solution, mix them at a volume ratio of 2:1, and add them to the complexing solution. Stir and mix evenly, adjust the pH to 6.0, and stir for 45 minutes.

[0059] Spray drying: The inlet temperature for spray drying is 160 °C and the outlet temperature is 77 °C to obtain a powder of selenium-rich bio-nutrient agent with excellent controlled-release performance. After drying, the particles are uniform and have good fluidity.

[0060] Example 5: Dissolve 1.5 g of cysteine, 1.5 g of glutathione and 0.5 g of β-carotene in 200 mL of deionized water, stir evenly, adjust the pH to 7.2, and stir for 25 minutes for later use.

[0061] Selenium complexation reaction: Prepare a 0.04% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.6 mL / min. Control the reaction temperature at 40 °C, set the stirring speed at 450 rpm, and the reaction time is 80 minutes.

[0062] Nanometer dispersion: Use a high-speed shear dispersion device to process the complex solution. The shear speed is 9,000 rpm and the dispersion time is 12 minutes. The particle size after dispersion is detected to be 120 nm.

[0063] Stabilization treatment: Prepare a 1.5% (w / v) chitosan solution, add it to the complex solution, mix evenly, stir for 40 minutes, and adjust the pH to 5.9 to form a stable complex solution.

[0064] Spray drying: Perform spray drying on the stable solution. The inlet temperature is 155 °C and the outlet temperature is 78 °C to obtain a highly soluble and stable bio-nutrient agent powder rich in organic selenium, which has good stability under storage conditions.

[0065] Comparative example: Comparative example 1: Selection of selenium source Difference: Based on Example 1, the selenium source is changed from selenocysteine to inorganic selenium (sodium selenite).

[0066] Preparation process: Pretreatment of ligand solution: Weigh 0.5 g of cysteine and 1.0 g of glutathione, dissolve them in 100 mL of deionized water, adjust the pH to 7.2, and stir for 20 minutes for later use.

[0067] Selenium complexation reaction: Prepare a 0.05% (w / v) sodium selenite solution and slowly add it dropwise to the ligand solution at a rate of 0.8 mL / min. Stir and react at 35 °C for 90 minutes, and the stirring speed is 400 rpm to obtain a complex solution.

[0068] Nanometer dispersion: High-speed shear dispersion, rotation speed 10,000 rpm, dispersion for 12 minutes, and the detected particle size is 150 nm.

[0069] Chitosan stabilization: Prepare a 2% (w / v) chitosan solution, adjust the pH to 6.0, add it to the complex solution at a volume ratio of 2:1, and stir for 40 minutes to mix evenly.

[0070] Spray drying: The inlet temperature of spray drying is 165 °C, and the outlet temperature is 80 °C to obtain a powdery product.

[0071] Comparative Example 2: Types and ratios of ligands Differentiating point: Based on Example 2, only a single ligand (cysteine) is used for the ligand, glutathione is not added, and the ratio of the ligand to the selenium source remains unchanged.

[0072] Preparation process: Preparation of ligand solution: Weigh 1.5 g of cysteine and dissolve it in 200 mL of deionized water, adjust the pH to 7.0, and stir for 25 minutes for standby.

[0073] Selenium complexation reaction: Prepare a 0.1% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.5 mL / min, stir at 40 °C for 75 minutes, and the stirring speed is 500 rpm to obtain a complex solution.

[0074] Nanometerization treatment Process the complex solution through a high-pressure homogenizer twice: Set the first homogenization pressure to 50 MPa for preliminary particle crushing; Set the second homogenization pressure to 80 MPa for further particle size homogenization.

[0075] Detect the particle size by dynamic light scattering method (DLS), and the results show that: The D50 value is 150 nm, the D10 value is 120 nm, and the D90 value is 185 nm, indicating that the particle size distribution range is relatively wide and the uniformity is poor.

[0076] Chitosan stabilization: Prepare a 1.5% (w / v) chitosan solution, adjust the pH to 5.8, add it to the complex solution at a volume ratio of 1:1, and stir for 50 minutes to mix evenly.

[0077] Spray drying: The inlet temperature is 150 °C, and the outlet temperature is 75 °C to obtain a powdery product.

[0078] Comparative Example 3: Selection of chitosan molecular weight Differentiating point: Based on Example 3, when performing the stabilization treatment, the chitosan molecular weight is changed from 10 - 50 kDa to 70 - 100 kDa.

[0079] Preparation process: Pretreatment of ligand and antioxidant: Weigh 1.0 g of cysteine, 2.0 g of glutathione, and 0.2 g of vitamin C and dissolve them in 150 mL of deionized water, adjust the pH to 7.3, and stir for 20 minutes.

[0080] Selenium complexation reaction: Prepare a 0.03% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 1 mL / min. Stir and react at 35 °C for 120 minutes with a stirring speed of 350 rpm to obtain a complex solution.

[0081] High-speed shear dispersion: Rotation speed is 12,000 rpm, time is 15 minutes. After dispersion, the particle size is detected to be 140 nm.

[0082] Chitosan stabilization: Prepare a 3% (w / v) chitosan solution using chitosan with a molecular weight of 80 kDa. Add it to the complex solution at a volume ratio of 1:1.5, stir and mix for 30 minutes, and adjust the pH to 6.0.

[0083] Spray drying: Feed temperature is 170 °C, discharge temperature is 80 °C. After drying, a powdery product is obtained.

[0084] Comparative Example 4: Process parameters of nanosizing Difference: Based on Example 4, during nanosizing dispersion treatment, the shear speed is reduced from 8,000 - 12,000 rpm to 5,000 rpm.

[0085] Preparation process: Ligand solution preparation: Weigh 2.0 g of glutathione and dissolve it in 100 mL of deionized water. Adjust the pH to 7.5, stir for 30 minutes, and keep the solution at 25 °C for standby.

[0086] Selenium complexation reaction: Prepare a 0.02% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.7 mL / min. The stirring speed is 400 rpm, the reaction temperature is 37 °C, and the reaction continues for 90 minutes to obtain a complex solution.

[0087] Nanosizing treatment: Process the complex solution through a high-speed shear disperser with a shear speed set at 5,000 rpm for 10 minutes.

[0088] Chitosan and sodium alginate stabilization treatment: Prepare a 2% (w / v) chitosan solution and a 1% (w / v) sodium alginate solution, mix them at a volume ratio of 2:1, add them to the complex solution, stir for 45 minutes, and adjust the pH to 6.0.

[0089] Spray drying: Spray drying feed temperature is 160 °C, discharge temperature is 77 °C. After drying, a powdery product is obtained.

[0090] Comparative Example 5: Selection of antioxidant Difference: Based on Example 5, the antioxidant β-carotene is omitted.

[0091] Preparation process: Preparation of ligand solution: Dissolve 1.5 g of cysteine and 1.5 g of glutathione in 200 mL of deionized water, stir evenly, adjust the pH to 7.2, and stir for 25 minutes for later use.

[0092] Selenium complexation reaction: Prepare a 0.04% (w / v) selenocysteine solution and add it dropwise to the ligand solution at a rate of 0.6 mL / min. The reaction temperature is 40 °C, the stirring speed is 450 rpm, and the reaction time is 80 minutes.

[0093] Nanomization and dispersion: Treat the complex solution with a high-speed shear dispersion device at a shear speed of 9,000 rpm for 12 minutes.

[0094] Chitosan stabilization: Prepare a 1.5% (w / v) chitosan solution, add it to the complex solution, mix evenly, stir for 40 minutes, and adjust the pH to 5.9 to form a stable complex solution.

[0095] Spray drying: The inlet temperature of spray drying is 155 °C, the outlet temperature is 78 °C, and a powdery product is obtained after drying.

[0096] Testing experiment: Experiment 1: Testing of selenium complexation efficiency Experiment description: The purpose of this experiment is to detect the complexation efficiency of selenium complexes in the examples and comparative examples by ultraviolet-visible spectroscopy, and verify the advantages of the present invention in terms of complexation efficiency. By measuring the characteristic absorption peak at 260 nm, calculate the proportion of complexed selenium, and compare the effects of selenium sources, ligand types and ratios on the complexation efficiency.

[0097] Experiment steps: Sample preparation: Prepare complex solutions according to the formulations of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, ensuring the same preparation conditions. Prepare 50 mL of complex solution for each group. The samples are used for testing immediately after preparation to avoid oxidation.

[0098] Dilution treatment: Dilute each group of samples at a ratio of 1:50, adjust to a uniform concentration with deionized water, and filter to remove particulate impurities to ensure consistent spectral test conditions.

[0099] Spectral determination: Measure the absorbance of each sample at 260 nm in an ultraviolet-visible spectrophotometer. Each group of samples is measured 3 times and the average value is taken. Use the ligand solution as a blank control to deduct the baseline effect.

[0100] Data processing: Calculate the complexation efficiency based on the absorbance value:

[0101] Experimental data: In this experiment, by testing the complexation efficiency of the examples and comparative examples, it was clearly demonstrated that the complexation efficiency of using selenocysteine and the composite ligand in the present invention is significantly superior to the prior art. The results show that selenocysteine acts synergistically with sulfur-containing ligands (cysteine and glutathione), and can significantly improve the complexation efficiency of selenium through a multi-point coordination strategy. This high-efficiency complexation is achieved by the synergistic coordination of the cysteine mercapto group and the glutathione carboxyl group, providing a more stable complex structure and avoiding the decomposition of free selenium.

[0102] In contrast, in Comparative Example 1, inorganic selenium (sodium selenite) was used as the selenium source. Due to its low chemical activity, the binding efficiency with the ligand decreased significantly, and the complexation efficiency only reached 63.8%. Inorganic selenium is also more easily oxidized during the reaction, resulting in a further weakening of the complexation effect. However, selenocysteine in the examples has a soft molecular structure itself, and its complexation with the ligand is tighter, thus significantly improving the complexation efficiency.

[0103] For Comparative Example 2, using only a single ligand (cysteine) also showed a relatively low complexation efficiency (80.7%), indicating that the complexation sites of the single ligand are insufficient and it is difficult to provide sufficient chemical stability. In contrast, when the mixing ratio of cysteine and glutathione in Example 2 is 1:3, due to the participation of the amino group and carboxyl group of glutathione in complexation to form a multi-point stable structure, the bonding strength of the selenium complex is further enhanced, so the complexation efficiency is as high as 96.4%.

[0104] The significant difference in selenium complexation efficiency not only stems from the choice of selenium source, but also benefits from the precise regulation of the ligand ratio. The design of the composite ligand can significantly improve the complexation efficiency while ensuring the stability of the complex. This result clearly demonstrates the creative advantages of the present invention and also provides a reliable experimental basis for the development of high-efficiency organic selenium nutritional agents.

[0105] Experiment 2: Nanometer dispersion performance test Experiment description: This experiment aims to verify the particle size distribution of the complexation solutions in the examples and comparative examples after nanometer dispersion treatment, evaluate the control effect of the dispersion process on the particle size uniformity, and highlight the superiority of the high-speed shear dispersion and high-pressure homogenization technologies in the present invention.

[0106] Experimental steps Sample preparation: Prepare complexation solutions according to the processes of Example 3, Example 4, Comparative Example 3, and Comparative Example 4 respectively, ensuring that the components and concentrations of the complexation solutions are the same. Immediately perform nanometer treatment after sample preparation.

[0107] Nanometer dispersion treatment: Example 3: High-speed shearing and dispersion, with the shearing speed set at 12,000 rpm and the time at 12 minutes.

[0108] Example 4: High-pressure homogenization treatment, with the homogenization pressure set at 80 MPa and circulated twice.

[0109] Comparative Example 3: The molecular weight of chitosan was increased to 80 kDa, and other dispersion conditions were the same as in Example 3.

[0110] Comparative Example 4: The shearing and dispersion speed was reduced to 5,000 rpm, and other conditions were the same as in Example 4.

[0111] Particle size measurement: The treated complex solution was diluted to a concentration of 0.1% (w / v) and filtered to remove impurities.

[0112] The particle size distribution was measured using dynamic light scattering (DLS), and the average particle size (Z-average particle size) and polydispersity index (PDI) were recorded.

[0113] Each group of samples was measured 3 times and the average value was taken.

[0114] Experimental data: The experimental results clearly demonstrated the significant influence of different dispersion processes and conditions on the particle size distribution of the complex. In Example 3 of the present invention, high-speed shearing and dispersion technology was adopted, and the particle size of the selenium complex was successfully controlled at about 128 nm, and the PDI value was as low as 0.19, showing high uniformity. This is due to the fact that high-speed shearing and dispersion can quickly break the aggregation structure between particles while providing mechanical shearing force, enabling the particles to be distributed under uniform conditions. In addition, the appropriate selection of the molecular weight of chitosan further reduced the possibility of cross-linking between particles, ensuring the controllability of the particle size.

[0115] In contrast, in Comparative Example 3, after the molecular weight of chitosan increased to 80 kDa, the particle size increased significantly to 185 nm, and the PDI value increased to 0.28, indicating uneven particle distribution. This is mainly because the chitosan molecular chain is longer, resulting in the formation of larger aggregates during the dispersion process of the complex, hindering the further refinement and homogenization of the particles. Although high molecular weight chitosan can provide strong protection, its high viscosity reduces the dispersion efficiency of mechanical force.

[0116] In Example 4, the high-pressure homogenization technology was adopted, and the particle size was further reduced to 112.7 nm, and the PDI value reached 0.17, showing excellent uniformity and stability. This high-efficiency dispersion performance stems from the strong liquid flow shear and impact effects exerted during the high-pressure homogenization process, which can effectively break the aggregation structure between particles and inhibit the re-aggregation of particles through the stabilizing effect of chitosan. However, in Comparative Example 4, after the shear speed decreased to 5,000 rpm, the particle size increased significantly to 234.7 nm, and the PDI increased to 0.35. This indicates that insufficient mechanical force results in the inability of particles to be fully dispersed, and partial aggregation may occur between particles, further increasing the particle size.

[0117] The quality of nano-dispersion performance is not only reflected in the size of the particle size, but also closely related to the uniformity of particle distribution. The successful application of high-speed shear and high-pressure homogenization technologies in the present invention not only optimizes the particle size, but also significantly improves the particle uniformity, ultimately enhancing the bioavailability of the complex. This technical advantage was not achieved in the comparative examples, further demonstrating the creativity and effectiveness of the process of the present invention.

[0118] Experiment 3: Selenium stability test Experiment description: The purpose of this experiment is to verify the selenium content stability of the complexes in the examples and comparative examples under different storage conditions, evaluate the effects of selenium source, ligand, and chitosan molecular weight on the stability of the complexes, and highlight the advantages of the multi-point coordination and chitosan stabilization strategies in the present invention.

[0119] Sample preparation: Selenium complex powder samples were prepared according to the processes of Example 1, Example 3, Comparative Example 1, and Comparative Example 3 respectively, ensuring that the initial selenium content was the same (0.05% w / w based on selenocysteine).

[0120] Storage condition setting: Room temperature condition: 25 °C, relative humidity 45%, stored for 30 days.

[0121] Accelerated aging condition: 40 °C, relative humidity 75%, stored for 30 days.

[0122] Selenium content detection: The remaining selenium content in the samples was detected by atomic fluorescence spectrometry (AFS).

[0123] Each group of samples was detected 3 times, the average value was calculated, and the selenium degradation rate was calculated:

[0124] Experimental data: The experimental results clearly show that the storage stability of selenium complexes is significantly affected by the selection of selenium sources, the type of ligands, and the molecular weight of chitosan. Examples 1 and 3 of the present invention exhibit significantly lower selenium degradation rates, indicating that the multi-point coordination strategy of selenocysteine and composite ligands makes an important contribution to the stability of the complexes. Multi-point coordination can effectively reduce the exposure of free selenium elements and avoid oxidation or dissociation. In contrast, Comparative Example 1 uses inorganic selenium (sodium selenite), and due to the lack of protection by organic groups, its selenium content rapidly decreases during storage, with a degradation rate of up to 21.4% at room temperature and nearly 35% under accelerated aging conditions, showing obvious insufficient stability.

[0125] In Example 3, the antioxidant capacity of the complex was further enhanced by adding vitamin C, enabling it to maintain 92.3% of its selenium content even under accelerated aging conditions. Combined with the protective layer of chitosan, the stability of the complex was further improved. In contrast, in Comparative Example 3, after the molecular weight of chitosan increased to 80 kDa, although it provided a certain degree of protection, the excessive molecular weight increased the viscosity of the system and reduced the dispersion uniformity, resulting in partial exposure of selenium to the oxidative environment, with a degradation rate of 15.5% at room temperature, and the storage stability was significantly lower than that of the examples.

[0126] The role of the molecular structure of chitosan in the protection of complexes is particularly prominent. A moderate molecular weight (10 - 50 kDa) can form a uniform protective barrier while maintaining the fluidity and dispersibility of the complexes. However, chitosan with a higher molecular weight has an increased degree of particle aggregation due to its overly long molecular chains, which disrupts the uniformity of the complexes. Through the precise regulation of the molecular weight of chitosan and the optimized selection of ligands and selenium sources, the present invention effectively improves the storage stability of the complexes, avoids the defect of easy degradation of traditional selenium preparations during transportation and storage, and fully demonstrates the advantages of technological innovation.

[0127] Experiment 4: Controlled Release Performance Test Experiment Description: This experiment aims to verify the controlled release performance of selenium complexes in the examples and comparative examples. By simulating the gastric juice and intestinal juice environments, the selenium release behavior of the complexes is evaluated to highlight the synergistic effect of chitosan and sodium alginate and the impact of nanometerization on the controlled release performance in the present invention.

[0128] Experimental Procedures: Sample Preparation: Complex powder samples were prepared according to the processes of Example 4, Example 5, Comparative Example 4, and Comparative Example 5, with 3 samples prepared for each group and the initial selenium content kept consistent (0.05% w / w).

[0129] Simulated Gastric Juice Release Test: Prepare simulated gastric juice (0.1 M HCl, pH 1.5).

[0130] Dissolve 0.5 g of the sample in 50 mL of simulated gastric fluid, place it in a water bath shaker at 37 °C with a rotation speed of 100 rpm.

[0131] Take 2 mL of the sample every 30 minutes, filter it, and then measure the released selenium concentration. Make up the sampled volume with simulated gastric fluid and test for 2 hours.

[0132] Simulated intestinal fluid release test: Prepare simulated intestinal fluid (50 mM phosphate buffer, pH 7.5).

[0133] After the gastric fluid test is completed, transfer the remaining sample to 50 mL of simulated intestinal fluid and continue to shake at 37 °C and 100 rpm.

[0134] Take 2 mL of the sample every 30 minutes, filter it, and then measure the released selenium concentration. Test for 6 hours.

[0135] Determination of selenium release amount: Use atomic fluorescence spectrometry (AFS) to detect the selenium concentration and calculate the release rate:

[0136] Experimental data: The experimental data show that the selenium complex in the examples exhibits excellent controlled release performance under the conditions of simulated gastric fluid and intestinal fluid, which is significantly better than that of the comparative examples. This improvement in performance is attributed to the synergistic effect of chitosan and sodium alginate. In Example 4, the combination of the cationic network structure formed by chitosan and the gelation of sodium alginate can form a stable protective barrier in the gastric acid environment, significantly reducing the initial release rate of selenium (only 15.9%). In the weakly alkaline condition of the small intestine, the chitosan in the complex gradually degrades, and along with the ion exchange effect of sodium alginate, selenium is slowly released, and the release rate reaches 84.3% within 6 hours.

[0137] In contrast, in Comparative Example 4, after reducing the shear dispersion rotation speed, the particle size of the complex significantly increases and the particle distribution is uneven. This results in a weakened barrier effect in the gastric acid environment, with an initial release rate as high as 26.3% and a significant decline in the controlled release effect. At the same time, the non-uniform release in the intestinal fluid reduces the total release rate to 58.5%. This difference further proves that the nanonization dispersion process can effectively enhance the dispersibility and uniformity of particles, thereby improving the controlled release effect.

[0138] In Example 5, the addition of an antioxidant (β-carotene) further enhanced the stability of the complex in the gastric acid environment, and the initial release rate decreased to 13.6%. In the intestinal fluid environment, β-carotene protected the selenium inside the complex from external oxidation, making the release process smoother, and the release rate reached 88.7% within 6 hours. In Comparative Example 5, β-carotene was omitted. Although the initial release rate (19.5%) in gastric juice was slightly lower than that in Comparative Example 4, the total release rate in small intestinal fluid decreased to 71.6%, showing a certain degree of instability.

[0139] The optimization of the controlled release performance not only depends on the physicochemical properties of the ligand and chitosan, but also is closely related to the nanosizing treatment and the cooperation of antioxidants. Through optimizing the dispersion technology and the synergistic stabilization strategy, the present invention successfully constructed a selenium complex that is stable in the gastric acid environment and efficiently releases in the small intestine environment, providing a new controlled release design idea for functional selenium-rich products and having obvious technological innovation advantages.

[0140] Experiment 5: Antioxidant Performance Test Experiment Description: In this experiment, through the DPPH free radical scavenging experiment, the antioxidant ability of the selenium complexes in the examples and comparative examples was verified, the influence of the addition and synergistic effect of antioxidants (vitamin C, β-carotene) on the free radical scavenging effect was evaluated, and the enhancement of the antioxidant performance of the complexes in the present invention was highlighted.

[0141] Experiment Steps: Sample Preparation: Selenium complex powder samples were prepared according to the processes of Example 3, Example 5, Comparative Example 3, and Comparative Example 5. Equal amounts of samples were taken to ensure that the selenium content was the same (0.05% w / w) and reserved for use.

[0142] Preparation of DPPH Solution: A 0.2 mM DPPH solution was prepared using absolute ethanol as the solvent and stored in the dark to ensure the stability of the solution.

[0143] Determination of Antioxidant Performance: Each group of samples was dissolved in absolute ethanol at a concentration of 1 mg / mL, thoroughly mixed, and 1 mL of the sample solution was added to 3 mL of the DPPH solution.

[0144] After reacting at room temperature in the dark for 30 minutes, the absorbance was measured using a UV-visible spectrophotometer at a wavelength of 517 nm.

[0145] The blank control was the DPPH solution, and ethanol was the blank baseline.

[0146] Calculation of Free Radical Scavenging Rate:

[0147] Repeated tests: Each group of samples was repeatedly measured 3 times, and the average value was taken.

[0148] Experimental data: The experimental data show that the examples of the present invention are significantly superior to the comparative examples in terms of antioxidant capacity. Especially in the case of adding antioxidants, the complex exhibits remarkable free radical scavenging ability. In Example 5, by adding a composite antioxidant of β-carotene and vitamin C, the scavenging rate reached 86.3%, far exceeding other groups. This benefits from the high reduction ability of vitamin C and the liposolubility of β-carotene. The synergistic effect of the two in the complex significantly enhances the ability to capture DPPH free radicals. At the same time, the synergistic effect of selenium and the antioxidant makes the selenium in the complex more stable, and its activity is fully released.

[0149] In contrast, in Example 3, only vitamin C was added as an antioxidant, and its free radical scavenging rate was 75.7%. Although the performance was excellent, there was a slight gap compared with Example 5. This shows that the contribution of β-carotene to antioxidant performance cannot be ignored. By binding with the liposolubility of the complex, β-carotene not only improves the antioxidant ability but also enhances the structural stability of the complex, further prolonging the duration of free radical scavenging.

[0150] The antioxidant capacity of the comparative example group was significantly lower than that of the examples. Among them, in Comparative Example 3, no antioxidant was added, and the scavenging rate was only 57.5%, indicating that the antioxidant performance of the complex is weak without protection. In Comparative Example 5, only vitamin C was added, and its scavenging rate was 63.7%. Although it was improved compared with Comparative Example 3, it was still much lower than that of the examples. This shows that the protective effect of a single antioxidant is limited and it is difficult to achieve a significant synergistic effect. The synergistic use of antioxidants not only enhances the antioxidant ability of the complex but also inhibits the degradation reaction induced by free radicals.

[0151] The present invention has achieved a significant improvement in the antioxidant performance of selenium complexes by optimizing the types and combinations of antioxidants. This characteristic is of great significance for extending the storage period of preparations and improving product quality, and further verifies the technical advantages of the present invention in the field of selenium-rich preparation development.

[0152] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A biological nutrient rich in organic selenium, characterized in that: The biological nutrient comprises the following components, in weight percentage: Selenium source: 0.02%~0.1%; Ligand: 0.15% to 0.8%, wherein the ligand comprises at least one of sulfur-containing amino acids and glutathione; Carrier stabilizer: 1% to 10%, wherein the carrier stabilizer is chitosan or its derivatives; Antioxidant: 0.02% to 0.1%, wherein the antioxidant includes at least one of vitamin C and β-carotene; Auxiliary materials: 60% to 80%, wherein the auxiliary materials include at least one of maltodextrin and sodium alginate.

2. The organic selenium-rich biological nutrient according to claim 1, characterized in that: The selenium source is selenocysteine.

3. The organic selenium-rich biological nutrient according to claim 1, characterized in that: The ligand is a combination of cysteine ​​and glutathione, and the weight ratio of the two is 1:1 to 1:

3.

4. The organic selenium-rich biological nutrient according to claim 1, characterized in that: The carrier stabilizer is chitosan, and the molecular weight of chitosan is 10-50 kDa.

5. The organic selenium-rich biological nutrient according to claim 1, characterized in that: The auxiliary material is a combination of maltodextrin and sodium alginate, and the weight ratio of maltodextrin to sodium alginate is 3:1 to 5:

1.

6. A method for preparing an organic selenium-rich biological nutrient according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Ligand solution pretreatment: dissolve the ligand in deionized water, adjust the pH to 7.0-7.5, and stir for 15-30 minutes; S2, selenium complexation reaction: slowly add the selenium source solution to the ligand solution, and react for 60 to 120 minutes at 35 to 40°C and a stirring speed of 300 to 500 rpm; S3, nano-dispersion: the complex reaction solution is subjected to high-speed shear dispersion, the dispersion speed is 8,000-12,000 rpm, and the time is 10-15 minutes; S4, stabilization treatment: add chitosan stabilizer solution, mix well and adjust pH to 5.5-6.0; S5. Drying finished product: The powder is prepared by spray drying, the spray drying feed temperature is 150-180°C, and the discharge temperature is 75-85°C.

7. The method for preparing a biological nutrient rich in organic selenium according to claim 6, characterized in that: The concentration of the ligand solution is 1% to 3% (w / v).

8. The method for preparing a biological nutrient rich in organic selenium according to claim 6, characterized in that: In the selenium complexation reaction, the dropwise addition rate of the selenium source solution is 0.5-1 mL / min.

9. The method for preparing a biological nutrient rich in organic selenium according to claim 6, characterized in that: The particle size of the complex after high-speed shear dispersion is 100-200 nm.

10. The method for preparing a biological nutrient rich in organic selenium according to claim 1, characterized in that: The concentration of the chitosan solution in the stabilization treatment step is 1% to 3% (w / v), and the mixing time is 30 to 60 minutes.

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