A vitamin A preparation for feed production and its preparation method

Abstract

The present invention discloses a vitamin A preparation for feed production and its preparation method, belonging to the technical field of vitamin A preparations. By mass, it includes the following raw materials: Add vitamin A to cyclohexane, add mesoporous hydroxyapatite and sodium dodecyl sulfate, stir for 2 - 3 h and then centrifuge to obtain a composite material; Grind chitosan quaternary ammonium salt and modified starch through a 200-mesh sieve, fully mix them, add a plasticizer and a gelling agent and mix evenly again, then transfer to deionized water and stir for 0.5 - 1 h to obtain a film-forming solution; Place the composite material in a coating pan, preheat to 40 °C, use a spray gun to spray the film-forming solution onto the surface of the composite material, and dry it. The vitamin A preparation obtained by the present invention not only has high stability, but also has good biocompatibility, can achieve the release of vitamin A in gastric juice, and has outstanding temperature resistance, humidity resistance and light resistance. When used as a feed additive, it has better stability and can better provide nutrient elements.

Description

Technical Field

[0001] The present invention belongs to the technical field of vitamin A preparations, and particularly relates to a vitamin A preparation for feed production and a preparation method thereof. Background Art

[0002] Natural feed raw materials contain various vitamins, but the content is insufficient. After formulating feed, artificial vitamins need to be supplemented. Vitamins are organic trace nutrient components in feed and are also coenzymes indispensable for animals to maintain normal physiological functions. Although the addition amount of vitamins in feed is very small, the effect is very significant. Animals lacking vitamins can develop various diseases, and normal growth and reproduction are hindered. Under the conditions of centralized feeding, animals have high production performance and require about twice as much vitamin as in normal cases.

[0003] Currently, 16 vitamins can be used as feed additives, and vitamin A is particularly important. Vitamin A (vitamin A) is also called retinol (its aldehyde derivative retinol) or anti-xerophthalmia factor, and has the following physiological functions for feeding animals: (1) maintaining normal visual function, (2) maintaining the health of epithelial tissue cells and promoting the synthesis of immunoglobulins, (3) maintaining normal growth and development of bones, (4) promoting growth and reproduction, (5) nutritional supplement; however, vitamin A has unstable chemical properties and is prone to addition, oxidation, polymerization, cleavage, dehydration and other reactions. Light, oxygen, heat and free radicals can initiate or accelerate these reactions. Currently, vitamin A is mostly coated by the microcapsule method to improve its stability, but this process has complex steps, difficult parameter control, high cost, and the obtained vitamin A microcapsules have poor stability and are easily damaged during high-temperature, high-humidity and high-pressure (such as granulation, puffing) processes in feed processing, increasing the loss rate of vitamin A and making it difficult to effectively play a beneficial role. Therefore, it is necessary to provide a more stable vitamin A preparation for feed production. Summary of the Invention

[0004] The purpose of the present invention is to provide a vitamin A preparation for feed production and a preparation method thereof to solve the problems in the background art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of a vitamin A preparation for feed production includes the following steps:

[0007] First step: Add vitamin A into cyclohexane, add mesoporous hydroxyapatite and sodium dodecyl sulfate, stir for 2 - 3 h and then centrifuge, wash the precipitate with cyclohexane, and dry it to constant weight at 80 - 85 °C to obtain a composite material;

[0008] Step 2: Grind chitosan quaternary ammonium salt and modified starch through a 200-mesh sieve. After fully mixing, add a plasticizer and a gelling agent and mix evenly again. Then transfer to deionized water and stir for 0.5 - 1 h to obtain a film-forming solution.

[0009] Step 3: Place the composite material in a coating pan, preheat to 40 °C, and at a rotation speed of 40 - 60 r / min, use a spray gun to spray the film-forming solution onto the surface of the composite material. Then dry at 100 - 110 °C to obtain the vitamin A preparation for feed production.

[0010] Based on the good biodegradability and biocompatibility of hydroxyapatite, in the present invention, vitamin A is first loaded onto a mesoporous hydroxyapatite carrier to avoid direct contact with external conditions, weaken the influence of external temperature, humidity, light, and air on vitamin A, and retain the biological activity of microbial A. However, the effect is still not ideal because mesoporous hydroxyapatite has high hydrophilicity and a large specific surface area, and its barrier performance is limited. Based on this, the present invention uses a film-forming solution for coating treatment, so that hydroxypropyl methylcellulose, modified starch, a plasticizer, and a gelling agent crosslink and form a film on the surface of the composite material, forming an organic barrier layer on the surface of the composite material to further isolate the adverse effects of water, oxygen, and light, and obtain a vitamin A preparation for feed production with high stability.

[0011] Further, in the first step, the dosage ratio of vitamin A, cyclohexane, mesoporous hydroxyapatite, and sodium dodecyl sulfate is 0.25 - 0.35 g: 100 mL: 0.75 - 1 g: 75 mg.

[0012] Further, in the second step, the mass ratio of chitosan quaternary ammonium salt, modified starch, plasticizer, gelling agent, and deionized water is 5.5 - 10: 1.5 - 4.5: 1.2 - 3.5: 0.5 - 1.5: 85 - 100.

[0013] Further, in the third step, the dosage ratio of the composite material to the film-forming solution is 1 kg: 5 mL.

[0014] Further, the modified starch is prepared through the following steps:

[0015] Step S1: Add amylose to a 30 wt% hydrogen peroxide solution, stir evenly, then add a 0.05 wt% copper sulfate solution and continue to mix evenly. Transfer to a round-bottom flask, preheat at 45 °C for 10 - 15 min, stir at 75 °C for 10 - 15 min, transfer to deionized water, stir at 100 °C for 30 - 40 min, then cool to room temperature, centrifuge at 3000 r / min for 20 min, take the supernatant and precipitate with absolute ethanol. Wash the precipitate repeatedly with an 80% (v / v) ethanol solution, and freeze-dry to obtain oxidized starch.

[0016] Step S2: Add oxidized starch into DMF and stir evenly. Then add the DMF solution of 7-amino-4-methylcoumarin, adjust the pH to 5 with acetic acid. Under nitrogen protection, heat up to 50 - 55 °C and react in the dark for 4 - 6 h. After the reaction, adjust the pH to 7 - 8 with 1 mol / L sodium hydroxide solution, carry out suction filtration. Wash the filter cake with absolute ethanol and then dry it at 50 °C to obtain the modified starch.

[0017] Furthermore, the dosage ratio of amylose, hydrogen peroxide solution, copper sulfate solution and deionized water is 60 g : 20 - 25 mL : 2 mL : 300 - 400 mL, and the mass ratio of the oxidized starch to 7-amino-4-methylcoumarin is 2.5 - 3.0 : 0.3 - 0.5.

[0018] The present invention oxidizes amylose by using hydrogen peroxide as the oxidant and copper sulfate as the catalyst, so that the hydroxyl groups of amylose are oxidized into aldehyde groups and carboxyl groups, laying a foundation for subsequent reactions. Then, using the oxidized starch as the raw material, a Schiff base reaction occurs between the aldehyde groups in its structure and the amino groups of 7-amino-4-methylcoumarin, introducing the coumarin structure into the starch structure through chemical bonds to obtain the modified starch. It can be seen that the modified starch not only has excellent film-forming property by itself, but also contains carboxyl groups, Schiff base structures and coumarin structures.

[0019] The mesoporous hydroxyapatite is obtained by the soft template method, which is well-known to those skilled in the art. The average pore diameter is 19.56 - 41.56 nm, and the specific surface area is 13.51 - 30.36 m 2 / g.

[0020] Furthermore, the degree of substitution of the quaternary ammonium salt of chitosan is 98%, and it is N-(2-hydroxy)propyl-3-trimethylammonium chloride chitosan.

[0021] Furthermore, the plasticizer is one or more of glycerol, sorbitol, polyethylene glycol - 400, propylene glycol, mannitol and xylitol.

[0022] Furthermore, the gelling agent is one or more of carrageenan, gellan gum, pectin, agar, gum, arabic gum, konjac gum and xanthan gum.

[0023] Furthermore, a vitamin A preparation for feed production is prepared by the above preparation method.

[0024] The beneficial effects of the present invention:

[0025] 1. The present invention provides a vitamin A preparation for feed production and a preparation method thereof. The obtained vitamin A preparation not only has high stability but also good biocompatibility. The film layer and mesoporous hydroxyapatite on the surface of the preparation are soluble under acidic conditions, enabling the release of vitamin A in gastric juice. Moreover, it has outstanding heat resistance, humidity resistance, and light resistance. When used as a feed additive, factors such as heat and humidity during the processing have less impact on it, with better stability, higher retention rate of active ingredients, and can better provide nutritional elements.

[0026] 2. The preparation method of the vitamin A preparation of the present invention is simple and has low requirements for production equipment and operation steps. First, the mesoporous hydroxyapatite carrier is used for loading. Utilizing its porous characteristics, vitamin A is adsorbed into the pores. On the one hand, it avoids direct contact with external conditions, weakens the influence of external temperature, humidity, light, and air on vitamin A, and effectively retains the biological activity of vitamin A. On the other hand, it converts liquid oily vitamin A into a solid composite material that is easy to process and package, facilitating subsequent operations such as stirring and film coating.

[0027] 3. The film-forming solution of the vitamin A preparation of the present invention is composed of quaternary ammonium salt of chitosan, modified starch, and other adjuvants. It has good film-forming properties. The quaternary ammonium salt of chitosan has good water solubility, adhesiveness, and permeability, and is positively charged in aqueous solution. The surface of the composite material is rich in hydroxyl groups and is negatively charged. An electrostatic interaction is formed between the positive and negative charges, causing the quaternary ammonium salt of chitosan to wind around the surface of the composite material. The modified starch is also water-soluble and can be combined with the quaternary ammonium salt of chitosan through hydrogen bond interactions between groups such as hydroxyl, amino, and carboxyl groups to form a cross-linked network structure, further playing a barrier role. Moreover, the surface of the modified starch contains a coumarin structure, which has antioxidant and ultraviolet absorption characteristics and can weaken the adverse effects of light and oxygen on vitamin A. Detailed implementation mode

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0029] Example 1

[0030] A kind of mesoporous hydroxyapatite is prepared through the following steps:

[0031] 0.3 g of cetyltrimethylammonium bromide, 0.45 g of diammonium hydrogen phosphate, and 0.64 g of anhydrous calcium chloride were successively added to 10 mL of deionized water, 30 mL of deionized water, and 30 mL of deionized water to obtain solution a, solution b, and solution c, respectively. The pH of each solution was adjusted to 10 with ammonia water. Then, solution a was added to solution b, and the mixture was stirred at 300 r / min for 30 min. After that, solution c was added dropwise. After the addition was completed, the mixture was stirred for 30 min and then transferred to a reaction kettle, where it was reacted at a constant temperature of 120 °C for 24 h. After cooling, it was centrifuged, and the precipitate was washed with deionized water until the washing liquid was neutral. After drying at 80 °C, it was calcined at 600 °C for 3 h, and then cooled to room temperature to obtain mesoporous hydroxyapatite.

[0032] Example 2

[0033] A modified starch is prepared through the following steps:

[0034] Step S1: 60 g of amylose was added to 20 mL of 30 wt% hydrogen peroxide solution. After stirring evenly, 2 mL of 0.05 wt% copper sulfate solution was added and the mixture was further mixed evenly. Then it was transferred to a round-bottom flask, preheated at 45 °C for 10 min, stirred at 75 °C for 10 min, transferred to 300 mL of deionized water, stirred at 100 °C for 30 min, and then cooled to room temperature. It was centrifuged at 3000 r / min for 20 min. The supernatant was taken and precipitated with absolute ethanol. The precipitate was repeatedly washed with 80% (v / v) ethanol solution and freeze-dried to obtain oxidized starch.

[0035] Step S2: 2.5 g of oxidized starch was added to 30 mL of DMF and stirred evenly. A solution composed of 0.3 g of 7-amino-4-methylcoumarin and 10 mL of DMF was added. The pH was adjusted to 5 with acetic acid. Under nitrogen protection, the temperature was raised to 50 °C and the reaction was carried out in the dark for 4 h. After the reaction was completed, the pH was adjusted to 7 - 8 with 1 mol / L sodium hydroxide solution. It was filtered by suction, and the filter cake was washed with absolute ethanol and dried at 50 °C to obtain the modified starch.

[0036] Example 3

[0037] A modified starch is prepared through the following steps:

[0038] Step S1: 60 g of amylose was added to 25 mL of 30 wt% hydrogen peroxide solution. After stirring evenly, 2 mL of 0.05 wt% copper sulfate solution was added and the mixture was further mixed evenly. Then it was transferred to a round-bottom flask, preheated at 45 °C for 15 min, stirred at 75 °C for 15 min, transferred to 400 mL of deionized water, stirred at 100 °C for 40 min, and then cooled to room temperature. It was centrifuged at 3000 r / min for 20 min. The supernatant was taken and precipitated with absolute ethanol. The precipitate was repeatedly washed with 80% (v / v) ethanol solution and freeze-dried to obtain oxidized starch.

[0039] Step S2: Add 3.0 g of oxidized starch into 40 mL of DMF and stir evenly. Then add the solution composed of 0.5 g of 7-amino-4-methylcoumarin and 10 mL of DMF. Adjust the pH to 5 with acetic acid. Under nitrogen protection, heat up to 55 °C and react for 6 h in the dark. After the reaction, adjust the pH to 7 - 8 with 1 mol / L sodium hydroxide solution, perform suction filtration, wash the filter cake with absolute ethanol, and dry it at 50 °C to obtain the modified starch.

[0040] Comparative Example 1

[0041] Compared with Example 2, this comparative example is the oxidized starch obtained in Step S1 of Example 2.

[0042] Example 4

[0043] A preparation method of a vitamin A preparation for feed production, comprising the following steps:

[0044] First step: Add 0.25 g of vitamin A into 100 mL of cyclohexane, add 0.75 g of the mesoporous hydroxyapatite of Example 1 and 75 mg of sodium dodecyl sulfate, stir for 2 h and then centrifuge. Wash the precipitate once with cyclohexane and dry it at 80 °C to constant weight to obtain the composite material; (weigh and record the mass of the composite material);

[0045] Second step: Grind 5.5 g of quaternary ammonium chitosan and 1.5 g of the modified starch of Example 2 through a 200-mesh sieve. After fully mixing, add 1.2 g of plasticizer and 0.5 g of gelling agent and mix evenly again. Then transfer it to 85 mL of deionized water and stir for 0.5 h to obtain the film-forming solution.

[0046] Third step: Place the composite material in a coating pan, preheat to 40 °C, and at a rotation speed of 40 r / min, use a spray gun to spray the film-forming solution onto the surface of the composite material. Then dry it at 100 °C to obtain the vitamin A preparation for feed production, and spray 5 mL of the film-forming solution per 1 kg of the composite material per minute.

[0047] The quaternary ammonium chitosan has a substitution degree of 98% and is N-(2-hydroxy)propyl-3-trimethylammonium chloride chitosan, HTCC, purchased from Dongying Tianhua Biological Auxiliary Co., Ltd. The plasticizer is glycerol and the gelling agent is carrageenan.

[0048] Example 5

[0049] A preparation method of a vitamin A preparation for feed production, comprising the following steps:

[0050] Step 1: Add 0.30 g of vitamin A to 100 mL of cyclohexane, add 0.85 g of the mesoporous hydroxyapatite of Example 1 and 75 mg of sodium dodecyl sulfate, stir for 2.5 h and then centrifuge. Rinse the precipitate once with cyclohexane and dry at 83° C. to constant weight to obtain a composite material (weigh and record the mass of the composite material);

[0051] Step 2: Grind 6.8 g of chitosan quaternary ammonium salt and 2.5 g of the modified starch of Example 3 through a 200-mesh sieve, mix thoroughly, add 2.5 g of plasticizer and 1.0 g of gelling agent, mix evenly again, transfer to 95 mL of deionized water, stir for 0.8 h, and obtain a film-forming solution;

[0052] The third step is to place the composite material in a coating pan, preheat it to 40°C, rotate at 50r / min, use a spray gun to spray the film-forming liquid onto the surface of the composite material, and then dry it at 105°C to obtain the vitamin A preparation for feed production. For every 1kg of composite material, 5mL of film-forming liquid is sprayed per minute.

[0053] The chitosan quaternary ammonium salt, with a substitution of 98%, is N-(2-hydroxy)propyl-3-trimethylammonium chloride chitosan, HTCC, purchased from Dongying Tianhua Biological Additive Co., Ltd., the plasticizer is propylene glycol, and the gelling agent is pectin.

[0054] Example 6

[0055] A method for preparing a vitamin A preparation for feed production comprises the following steps:

[0056] Step 1: Add 0.35 g of vitamin A to 100 mL of cyclohexane, add 1 g of the mesoporous hydroxyapatite of Example 1 and 75 mg of sodium dodecyl sulfate, stir for 3 h and then centrifuge. Rinse the precipitate once with cyclohexane and dry at 85° C. to constant weight to obtain a composite material (weigh and record the mass of the composite material);

[0057] Step 2: Grind 10 g of chitosan quaternary ammonium salt and 4.5 g of the modified starch of Example 3 through a 200-mesh sieve, mix thoroughly, add 3.5 g of plasticizer and 1.5 g of gelling agent, mix well again, transfer to 100 mL of deionized water, stir for 1 h, and obtain a film-forming solution;

[0058] The third step is to place the composite material in a coating pan, preheat it to 40°C, rotate at 60r / min, use a spray gun to spray the film-forming liquid onto the surface of the composite material, and then dry it at 110°C to obtain the vitamin A preparation produced in the feed. For every 1kg of the composite material, 5mL of the film-forming liquid is sprayed per minute.

[0059] The chitosan quaternary ammonium salt, with a substitution degree of 98%, is N-(2-hydroxy)propyl-3-trimethyl ammonium chloride chitosan, HTCC, purchased from Dongying Tianhua Biological Auxiliary Co., Ltd. The plasticizer is mannitol, and the gelling agent is gellan gum.

[0060] Comparative Example 2

[0061] Compared with Example 4, the modified starch in Example 4 was replaced with the substance in Comparative Example 1, and the remaining raw materials and preparation process were the same as those in Example 4.

[0062] Comparative Example 3

[0063] This comparative example is the composite material in the first step of Example 4.

[0064] The final products obtained from Example 4 - Example 6 and Comparative Example 2 - Comparative Example 3 were weighed. The vitamin A loading amount was obtained by subtracting the mass of mesoporous hydroxyapatite from the mass of each composite material. The vitamin A loading rate of each group of products was calculated by using vitamin A loading amount / final product mass × 100%. Then, performance tests were carried out, and the test contents are as follows:

[0065] I. Dissolution test

[0066] Preparation of simulated gastric juice: Take 4.5 mL of concentrated hydrochloric acid (37 wt%), add 400 mL of water, add 4 g of surfactant SDS to make vitamin A miscible with simulated gastric juice, adjust the pH value to 1.2 with 4 mol / L hydrochloric acid, and then make the solution up to 500 mL with deionized water. Keep it at 37 °C for later use. Respectively take 1 g of each group of vitamin A preparations and place them in a 100 mL simulated environment at 37 °C. Stir at a speed of 30 rpm under constant temperature conditions. Take out 5 mL of the solution at 6 min and supplement it with 5 mL of simulated solution. Filter it through a 0.45 μm filter membrane and dilute it. Measure the absorbance at 326 nm, substitute it into the regression curve to calculate the concentration of vitamin A in the solution at the sampling time, and thus obtain the release amount of the complex in simulated gastric juice at 37 °C within 6 min, and calculate the vitamin A dissolution rate (dissolution rate = release amount / vitamin A loading amount × 100%, vitamin A loading amount = corresponding vitamin A loading rate × 1 g);

[0067] II. High-temperature test

[0068] Take 0.1 g of each group of vitamin A reagents to be tested, place them in an open measuring container, and put them in an environment with a temperature of 50 °C. Conduct sampling research on the eleventh day. Immediately dissolve them in 50 mL of hydrochloric acid ethanol solution (pH = 1) after weighing, dilute and stir. Control the temperature at 25 °C and stir continuously for one hour. Then take out some of the liquid, filter it through a 0.45 μm filter membrane, dilute it several times as required, and measure the absorbance at 326 nm with a UV spectrophotometer. Use the standard curve formula to calculate the drug mass in the original solution, and calculate the vitamin A retention rate (retention rate = drug mass in the solution after 10 days / vitamin A loading amount × 100%, vitamin A loading amount = corresponding vitamin A loading rate × 0.1 g);

[0069] III. High humidity test

[0070] Take 0.1 g of each group of vitamin A reagents to be tested and place the naked drugs in an open weighing bottle. Store them at room temperature of 25 °C and relative humidity of 90 ± 2%. Conduct sampling research on the eleventh day. Immediately dissolve them in 50 mL of hydrochloric acid ethanol solution (pH = 1) after weighing, dilute and stir. Control the temperature at 25 °C and stir continuously for one hour. Then take out some of the liquid, filter it through a 0.45 μm filter membrane, dilute it several times as required, and measure the absorbance at 326 nm with a UV spectrophotometer. Use the standard curve formula to calculate the drug mass in the original solution, and calculate the vitamin A retention rate (retention rate = drug mass in the solution after 10 days / vitamin A loading amount × 100%, vitamin A loading amount = corresponding vitamin A loading rate × 0.1 g);

[0071] IV. Light exposure test

[0072] Take 0.1 g of each group of vitamin A reagents to be tested and place them in an open weighing bottle. Place them in an environment with an illuminance standard of 4500 lx ± 500 lx. Take 0.1 g of each group of vitamin A reagents to be tested and conduct sampling observation on the 10th day. Immediately dissolve them in 50 mL of hydrochloric acid ethanol solution (pH = 1) after weighing, dilute and stir. Control the temperature at 25 °C and stir continuously for one hour. Then take out some of the liquid, filter it through a 0.45 μm filter membrane, dilute it several times appropriately as required, and measure the absorbance at 326 nm with a UV spectrophotometer. Use the standard curve formula to calculate the drug mass in the original solution, and calculate the vitamin A retention rate (retention rate = drug mass in the solution after 10 days / vitamin A loading amount × 100%, vitamin A loading amount = corresponding vitamin A loading rate × 0.1 g);

[0073] The results are shown in Table 1:

[0074] Table 1

[0075]

[0076] As can be seen from Table 1, the vitamin A preparations obtained in Examples 4-6 and Comparative Examples 2-3 have good solubility in gastric juice. However, compared with Comparative Examples 2-3, the vitamin A preparations prepared in Examples 4-6 have more prominent temperature resistance, humidity resistance and light resistance. When used as feed additives, the retention rate of active ingredients is better, and they can provide nutritional elements better.

[0077] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0078] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood 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 preparation method of a vitamin A preparation for feed production, characterized in that, it comprises the following steps: First step: Add vitamin A into cyclohexane, add mesoporous hydroxyapatite and sodium dodecyl sulfate, stir for 2 - 3 h and then centrifuge. Wash the precipitate with cyclohexane and dry it to constant weight at 80 - 85 °C to obtain a composite material; Second step: Grind chitosan quaternary ammonium salt and modified starch through a 200 - mesh sieve. After fully mixing, add a plasticizer and a gelling agent and mix evenly again. Then transfer it to deionized water and stir for 0.5 - 1 h to obtain a film - forming solution; Third step: Place the composite material in a coating pan, preheat it to 40 °C, and at a rotation speed of 40 - 60 r / min, use a spray gun to spray the film - forming solution onto the surface of the composite material. Then dry it at 100 - 110 °C to obtain the vitamin A preparation for feed production; The modified starch is prepared through the following steps: Add amylose into a 30 wt% hydrogen peroxide solution, stir evenly, then add a 0.05 wt% copper sulfate solution and continue to mix evenly. Transfer it to a round - bottom flask, preheat it at 45 °C for 10 - 15 min, stir at 75 °C for 10 - 15 min, transfer it to deionized water, stir at 100 °C for 30 - 40 min, then cool it to room temperature, centrifuge at 3000 r / min for 20 min, take the supernatant and precipitate it with absolute ethanol. Wash the precipitate repeatedly with an 80% (volume fraction) ethanol solution and freeze - dry it to obtain oxidized starch; Add the oxidized starch into DMF and stir evenly. Add a DMF solution of 7 - amino - 4 - methylcoumarin, adjust the pH to 5 with acetic acid. Under nitrogen protection, heat it to 50 - 55 °C and react in the dark for 4 - 6 h. After the reaction, adjust the pH to 7 - 8 with a 1 mol / L sodium hydroxide solution, filter by suction. Wash the filter cake with absolute ethanol and dry it at 50 °C to obtain the modified starch.

2. The preparation method of a vitamin A preparation for feed production according to claim 1, characterized in that, the dosage ratio of vitamin A, cyclohexane, mesoporous hydroxyapatite and sodium dodecyl sulfate is 0.25 - 0.35 g: 100 mL: 0.75 - 1 g: 75 mg.

3. The preparation method of a vitamin A preparation for feed production according to claim 1, characterized in that, the mass ratio of chitosan quaternary ammonium salt, modified starch, plasticizer, gelling agent and deionized water is 5.5 - 10: 1.5 - 4.5: 1.2 - 3.5: 0.5 - 1.5: 85 - 100.

4. The preparation method of a vitamin A preparation for feed production according to claim 1, characterized in that, the dosage ratio of the composite material and the film - forming solution is 1 kg: 5 mL.

5. The preparation method of a vitamin A preparation for feed production according to claim 1, characterized in that, the dosage ratio of the amylose, hydrogen peroxide solution, copper sulfate solution and deionized water is 60 g: 20 - 25 mL: 2 mL: 300 - 400 mL.

6. The preparation method of a vitamin A preparation for feed production according to claim 1, characterized in that, The mass ratio of the oxidized starch to 7-amino-4-methylcoumarin is 2.5-3.0:0.3-0.

5.

7. A vitamin A preparation for feed production, characterized in that, it is prepared by the preparation method described in any one of claims 1-6.

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