Preparation method and application of zinc selenomethionine chelate

Abstract

The invention relates to a preparation method and application of a zinc selenomethionine chelate, and belongs to the technical field of feed additives. The method comprises the following steps: taking water as a solvent in a high-pressure reaction kettle, adding selenomethionine, a zinc source and a pH regulator, regulating the pH to 6-10, carrying out hydrothermal reaction for 0.5-2 hours under the conditions of 130-200 DEG C and 3-12 MPa, and after the reaction is finished, cooling, filtering, washing and drying to obtain the 2: 1 type zinc selenomethionine chelate. The hydrothermal synthesis method is adopted, the reaction is thorough, the product purity and stability are high, the solvent dosage is small, the zinc source selection range is wide, and the method is suitable for multiple zinc sources such as zinc oxide and zinc sulfate. The prepared chelate can be used as an efficient feed additive, is applied to livestock and poultry feed, can remarkably improve the production performance of laying hens and egg quality, and has excellent popularization and application values.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of feed additives, in particular to a preparation method and application of a zinc selenomethionine chelate. BACKGROUND

[0002] Selenium is an important trace element nutrient supplement, which exists in the form of independent minerals, isomorphism or clay mineral adsorption in nature. Selenium in the environment can be divided into two categories: organic selenium and inorganic selenium. Organic selenium refers to compounds formed by selenium combined with carbon, hydrogen, oxygen, nitrogen and other elements, such as selenoprotein, yeast selenium, selenized carrageenan and selenomethionine. Compared with inorganic selenium (such as sodium selenite, sodium selenate), organic selenium has higher bioavailability and lower toxicity, and is more easily absorbed and utilized by the body.

[0003] At present, the research on selenomethionine mainly focuses on synthesis technology and mixture separation, and the research on the preparation of chelates combined with trace elements is still relatively limited. Patent US6911550 reports a water-soluble zinc selenomethionine salt (1:1 type) complex, which can be used as a selenium nutrient supplement for ruminants, but the complex lacks a cyclic chelate structure, has poor stability, and is easily decomposed in the intestinal tract, reducing its nutritional value. Patent CN1218043A proposes a preparation method of selenomethionine chromium, which has potential application value in the prevention and treatment of diabetes, cancer, cardiovascular diseases and other diseases, and can also be used in the field of nutrition and health care. SUMMARY

[0004] The present application provides a 2:1 type zinc selenomethionine chelate and its preparation method and application, enriching the preparation method of selenomethionine derivatives and expanding the application scenarios of selenomethionine as a new type of feed additive.

[0005] The preparation method of the zinc selenomethionine chelate comprises the following steps: (1) adding water as a solvent in a high-pressure reaction kettle; (2) sequentially adding selenomethionine, a zinc source and a pH adjuster into the high-pressure reaction kettle, and adjusting the pH of the reaction system to 6-10; (3) closing and sealing the kettle cover, maintaining the reaction temperature at 130-200℃, the reaction pressure at 3-12 MPa, and carrying out hydrothermal reaction under stirring conditions for 0.5-2 h; (4) stopping heating, cooling to below 45℃ with cooling water and restoring the pressure to normal pressure (about 0.1 MPa), then stopping stirring, opening the kettle cover and pouring out the reaction liquid; (5) performing vacuum filtration on the reaction liquid, and washing the filter cake with deionized water for 1-2 times; (6) drying the washed filter cake at 103℃ for 2-4 h to obtain the zinc selenomethionine chelate.

[0006] Preferably, the high-pressure reactor is made of 304, 316L or 2205 stainless steel, more preferably 316L stainless steel.

[0007] Preferably, the selenomethionine is L-selenomethionine or DL-selenomethionine with a purity of not less than 95%, and more preferably L-selenomethionine with a purity of 98%.

[0008] Preferably, the zinc source has a purity of not less than 95% and can be selected from any one or more of zinc oxide, zinc hydroxide, zinc chloride, zinc sulfate and its hydrates, zinc carbonate, and basic zinc carbonate, and more preferably zinc oxide with a purity of not less than 95%.

[0009] Preferably, the pH adjuster is sodium hydroxide, potassium hydroxide, or ammonia, more preferably sodium hydroxide.

[0010] Preferably, the pH value of the reaction system is 7-9.

[0011] Preferably, the molar ratio of selenomethionine to zinc source is (1.5~2.5):1. More preferably, it is 2:1.

[0012] Preferably, the amount of solvent water added is 0.5 to 2 times the total mass of selenomethionine and zinc source, more preferably 1 time.

[0013] Preferably, the reaction temperature is 150~180℃.

[0014] Preferably, the reaction pressure is 8~10 MPa.

[0015] Preferably, the hydrothermal reaction time is 1 hour.

[0016] This invention utilizes a hydrothermal method to prepare selenomethionine zinc chelates. The reaction is more thorough under high temperature and high pressure conditions, significantly improving the solubility and reactivity of the materials. This method requires less water as a solvent, and the zinc source can be a substance that is poorly soluble under normal pressure, broadening the applicability of the reaction. The prepared 2:1 chelate exhibits stable structure, high purity, and good biological potency, making it suitable for use as a feed additive.

[0017] The structural formula of the selenomethionine zinc chelate is as follows: The molar ratio of selenomethionine to zinc is 2:1. By adjusting the feed ratio, different contents of the target product can be prepared to meet diverse needs.

[0018] The present invention has the following beneficial effects: (i) The amount of solvent water used is small, and the range of zinc sources can be wide; (ii) The product has a 2:1 chelate structure, the reaction is complete, and the purity and stability are high; (iii) It can be used as a high-efficiency feed additive. Attached Figure Description

[0019] Figure 1 The infrared spectra of selenomethionine and selenomethionine zinc are shown.

[0020] Figure 2 The XRD diffraction patterns of selenomethionine and zinc selenomethionine are shown.

[0021] Figure 3 This is the infrared spectrum of zinc selenomethionine. Detailed Implementation

[0022] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0023] Example 1 Add 300g of water to a 1L high-pressure reactor, then add 250g of L-selenomethionine (98% purity), 53.5g of zinc oxide (95% purity), and 10g of sodium hydroxide (95% purity) sequentially, adjusting the pH to 7-8. Close and seal the reactor lid, heat to 180℃ (8.3 MPa pressure), and stir the reaction for 1 h. Stop the reaction, cool to 44℃, restore the pressure to near atmospheric pressure (0.1 MPa), unscrew the reactor lid, pour out the reaction solution, filter under reduced pressure, wash the filter cake twice with deionized water (100 mL each time), and dry at 103℃ for 4 h to obtain 296.4g of product.

[0024] Example 2 The procedure was the same as in Example 1, except that the zinc source was changed to 73.8g of basic zinc carbonate (95% purity), the reaction temperature was 160℃ (pressure 9.2 MPa), and 294.7g of product was obtained.

[0025] Example 3 The procedure was the same as in Example 1, except that the zinc source was changed to 64.5g of zinc hydroxide (96% purity), the pH was adjusted to 8-9, the reaction temperature was 160℃ (pressure 8.1 MPa), and 291.7g of product was obtained.

[0026] Example 4 The procedure was the same as in Example 1, except that the zinc source was changed to 116.5g of zinc sulfate monohydrate (96% purity), the pH was adjusted to 8-9, the reaction temperature was 160℃ (pressure 8.5 MPa), and 293.5g of product was obtained.

[0027] Example 5 The procedure was the same as in Example 1, except that the pH adjuster was replaced with 10g of potassium hydroxide (95% purity), the reaction temperature was 130℃ (pressure 7.4 MPa), the reaction time was 2 h, and 294.6g of product was obtained.

[0028] To further illustrate the advantages of the preparation method of selenomethionine zinc chelate provided by this invention, a comparative experiment was conducted in conjunction with existing technologies.

[0029] Comparative Example 1 Add 300g of water to a 1L three-necked flask, then add 250g of L-selenomethionine (98% purity), 53.5g of zinc oxide (95% purity), and 10g of sodium hydroxide (95% purity) sequentially, measuring the pH to 7-8. Start stirring and heat to 90℃, reacting for 2 hours. Stop the reaction, filter, wash the filter cake twice with deionized water (100mL each time), and dry at 103℃ for 4 hours to obtain 235.5g of product.

[0030] Comparative Example 2 The procedure was the same as in Comparative Example 1, except that the water was changed to 600g and the reaction time was 3 hours, yielding 229.4g of product.

[0031] Comparative Example 3 The procedure was the same as in Comparative Example 1, except that the zinc source was changed to 116.5g of zinc sulfate monohydrate (96% purity), yielding 256.7g of product.

[0032] Comparative Example 4 Using the same high-pressure reaction apparatus and procedures as in Example 1, but without adding sodium hydroxide pH adjuster, the pH of the reaction system was <6, and 274.6g of product was obtained.

[0033] Comparative Example 5 The same high-pressure reaction apparatus and procedures as in Example 1 were used, but the amount of sodium hydroxide (95% purity) added was changed to 18g, so that the pH of the reaction system was greater than 10, and 287.2g of product was obtained.

[0034] The product detection data for the examples and comparative examples are shown in Table 1 below. The theoretical values ​​are calculated based on the molecular structure of selenomethionine zinc chelate (molecular formula C10H20N2O4Se2Zn, M = 455.58). Zinc content was determined according to the method in GB21694-2017, nitrogen content was determined according to the Kjeldahl method, yield was obtained directly from product weighing, and purity was obtained by dividing the measured zinc / nitrogen content by the theoretical content.

[0035] Table 1. Detection data of products from the examples and comparative examples. The results showed that the Zn content, N content, and m(Zn) / m(N) ratio of the products prepared in the examples were all highly close to the theoretical values, and the product purity reached over 96%, demonstrating good structural consistency and high purity. In contrast, the comparative reaction was significantly less effective, further confirming the significant advantages of the method of the present invention in the synthesis of 2:1 type selenomethionine zinc chelates.

[0036] Comparative Examples 1-3 were carried out under normal pressure, and the Zn and N contents and the m(Zn) / m(N) ratio of their products deviated significantly from the theoretical values, indicating that reactions under normal pressure are difficult to effectively generate the target chelate. Although Comparative Examples 4-5 were carried out under high pressure, the pH values ​​of the reaction systems deviated from the required range of 6-10 (Comparative Example 4 pH < 6, Comparative Example 5 pH > 10), resulting in m(Zn) / m(N) ratios of the obtained products that significantly deviated from the theoretical values. This demonstrates that even with high pressure, uncontrolled pH can lead to abnormal product structures, decreased purity, and the inability to form the correct 2:1 chelate structure. This highlights the necessity and rigor of combining pH control with high pressure conditions in this invention.

[0037] According to selenomethionine zinc chelate (molecular formula C) 10 The molecular structure of H₂ON₂O₄Se₂Zn (M = 455.58) has a theoretical selenium content of: Se% = (2 × 78.97) / 455.58 × 100% ≈ 34.66%. The atomic ratio of nitrogen to selenium in this molecule is 1:1, therefore there is a definite stoichiometric relationship between nitrogen and selenium content, and the selenium content can be indirectly calculated by measuring the nitrogen content. Meanwhile, the mass ratio of m(Zn) / m(N) is a key indicator for judging the formation of the chelate structure, with a theoretical value of 2.3333. The closer this ratio is to the theoretical value, the closer the product is to the ideal 2:1 chelate structure; a significant deviation indicates incomplete reaction or the presence of a large number of impurities.

[0038] The m(Zn) / m(N) ratios of Comparative Examples 1-5 all deviated significantly from the theoretical values, and the Zn and N contents also differed considerably from the theoretical values, indicating that their enantiomeric products were not the target chelates and that unreacted zinc sources, selenomethionine, or other byproducts may have been present. This result further demonstrates the significant advantages of the method of this invention in the efficient and highly selective synthesis of stable chelates.

[0039] Figure 1 and Figure 2 The results showed that the infrared absorption peaks and XRD patterns of the product and the raw material changed significantly, further confirming the formation of selenomethionine zinc chelate.

[0040] Example 6: Animal Experiment (1) Purpose of the experiment To investigate the effects of different amounts of zinc selenomethionine on the laying performance and egg quality of laying hens, and to screen for the appropriate addition amount.

[0041] (2) Experimental materials and methods Experimental animals: 360 healthy 280-day-old Lohmann Brown laying hens with similar weight and egg production rate were randomly divided into 4 groups, with 3 replicates in each group and 30 laying hens in each replicate.

[0042] Experimental diets: The composition and nutrient levels of the basal diets are shown in Table 2 below. The experimental groups were supplemented with 0.1, 0.3, and 0.5 mg / kg of selenomethionine zinc, respectively, in their basal diets, while the control group was fed the basal diet.

[0043] Table 2. Basal Diets and Nutrient Levels Premix (per kg): VA: 1875 IU; VD3: 620 IU; VE: 2.25 IU; VK: 0.3 mg; VB1: 0.15 mg; VB2: 1.3 mg; VB6: 1.2 mg; VB12: 0.75 mg; Calcium pantothenate: 7.5 mg; Niacin: 5 mg; Biotin: 0.3 mg; Folic acid: 1 mg; Choline: 75 mg; Mn: 10 mg; I: 0.15 mg; Fe: 9 mg; Cu: 1.2 mg; Zn: 10 mg. Experimental design: The experimental period was 60 days, with a pre-trial period of 7 days. During the experiment, all laying hens were housed in three-tiered cages with free access to feed and water. The lighting duration was 16 h / d, the light intensity was 15-20 lux, the house temperature was 18-25℃, and the relative humidity was 60-70%. The conventional feeding and management procedures were followed.

[0044] Measurement indicators and methods: Production performance: Record the number of eggs laid, egg weight, and feed consumption of each group of laying hens daily, and calculate the laying rate (laying rate = total number of eggs laid / total number of hens × 100%), average egg weight (total egg weight / total number of eggs laid), and feed conversion ratio (feed consumption / egg production).

[0045] Egg quality: At the end of the experiment, 30 eggs were randomly selected from each group to determine the selenium content (using atomic fluorescence spectrometry), eggshell strength (using an eggshell strength tester), and yolk color (using a Roche colorimetric fan).

[0046] (3) Experimental results and analysis Effects of zinc selenomethionine on laying hen performance: As shown in the table below, compared with the control group, the experimental groups showed increased egg production rate and average egg weight, and decreased feed conversion ratio. Specifically, the egg production rate and average egg weight of the group supplemented with 0.3 mg / kg zinc selenomethionine were significantly higher than those of the control group (P<0.05), and the feed conversion ratio was significantly lower (P<0.05). The egg production rate and average egg weight of the group supplemented with 0.5 mg / kg zinc selenomethionine were not significantly different from those of the 0.3 mg / kg group (P>0.05), but the feed conversion ratio was slightly higher in the 0.5 mg / kg group.

[0047] Table 3. Effects of zinc selenomethionine on laying hen production performance. Effects of zinc selenomethionine on egg quality: As shown in the table below, with the increase of zinc selenomethionine addition, the selenium content in eggs gradually increased, and all experimental groups were significantly higher than the control group (P<0.05). The eggshell strength of the 0.3 mg / kg and 0.5 mg / kg zinc selenomethionine addition groups was significantly higher than that of the control group and the 0.1 mg / kg group (P<0.05). The yolk color deepened with the increase of zinc selenomethionine addition, and the 0.3 mg / kg and 0.5 mg / kg groups were significantly higher than that of the control group (P<0.05).

[0048] Table 4. Effects of selenomethionine zinc on egg quality (4) Conclusion Under the conditions of this experiment, adding selenomethionine zinc to the basal diet of laying hens can improve the laying rate and average egg weight, reduce the feed conversion ratio, and increase the selenium content in the eggs, as well as improve eggshell strength and yolk color. Taking all factors into account, the optimal addition level of selenomethionine zinc to the basal diet of laying hens is 0.3 mg / kg, with a recommended range of 0.1–0.5 mg / kg.

[0049] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, combinations, modifications and simplifications made without departing from the principles of the present invention should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a zinc chelate of selenomethionine, characterized in that, Includes the following steps: (1) Add water as a solvent to the high-pressure reactor; (2) Add selenomethionine, zinc source and pH adjuster in sequence to adjust the pH of the reaction system to 6-10; (3) Close and seal the reactor lid, and stir the reaction at 130~200℃ and 3~12 MPa for 0.5~2 h; (4) Stop heating, cool to below 45°C and restore the pressure to normal, then remove the reaction solution; (5) Filter the reaction solution under reduced pressure, and wash the filter cake with deionized water 1-2 times; (6) The washed filter cake was dried at 103°C for 2-4 h to obtain the selenomethionine zinc chelate.

2. The preparation method according to claim 1, characterized in that, The high-pressure reactor is made of 304, 316L or 2205 stainless steel.

3. The preparation method according to claim 1, characterized in that, The selenomethionine is L-selenomethionine or DL-selenomethionine with a purity of not less than 95%.

4. The preparation method according to claim 1, characterized in that, The zinc source has a purity of not less than 95% and is selected from one or more of zinc oxide, zinc hydroxide, zinc chloride, zinc sulfate and its hydrates, zinc carbonate, and basic zinc carbonate.

5. The preparation method according to claim 1, characterized in that, The pH adjuster is sodium hydroxide, potassium hydroxide, or ammonia.

6. The preparation method according to claim 1, characterized in that, The pH value of the reaction system is 7-9.

7. The preparation method according to claim 1, characterized in that, The molar ratio of selenomethionine to zinc source is (1.5~2.5):

1.

8. The preparation method according to claim 1, characterized in that, The amount of water added as solvent is 0.5 to 2 times the total mass of selenomethionine and zinc source.

9. The preparation method according to claim 1, characterized in that, The reaction temperature is 150~180℃, the reaction pressure is 8~10 MPa, and the hydrothermal reaction time is 1 h.

10. A selenomethionine zinc chelate prepared by the method according to any one of claims 1 to 9 is used in the preparation of livestock and poultry feed additives.

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