阅读说明：本技术 一种维生素a微胶囊的制备方法 (Preparation method of vitamin A microcapsule ) 是由 李莉 刘伟杰 郑兵 刘英瑞 高洪坤 王延斌 张涛 于 2021-09-14 设计创作，主要内容包括：本发明提供了一种维生素A微胶囊的制备方法,将保护性胶体、填充剂、抗氧剂、乳化剂加热溶解形成水溶性胶体,向其中加入壳聚糖吸附剂,并送入砂磨机进行研磨,再将维生素A晶体分散于所述水溶性胶体中,循环研磨形成维生素A悬浮液,最终形成粒径低于200nm的维生素A纳米乳液,经喷雾干燥、交联后得到维生素A微胶囊。本发明的方法不使用植物油,也无需高温溶解维生素A,避免了高温条件下维生素A的异构及损失,大大提高了其生物利用度及安全性,并且水相和油相抗氧剂复配使用,双层保护VA,大大提高了微胶囊的稳定性。(The invention provides a preparation method of vitamin A microcapsules, which comprises the steps of heating and dissolving protective colloid, filling agent, antioxidant and emulsifier to form water-soluble colloid, adding chitosan adsorbent into the water-soluble colloid, feeding the water-soluble colloid into a sand mill for grinding, dispersing vitamin A crystals into the water-soluble colloid, circularly grinding to form vitamin A suspension, finally forming vitamin A nano emulsion with the particle size of less than 200nm, and obtaining the vitamin A microcapsules after spray drying and crosslinking. The method does not use vegetable oil or dissolve vitamin A at high temperature, avoids the isomerization and loss of vitamin A under the high-temperature condition, greatly improves the bioavailability and the safety of the vitamin A, and the VA is protected by double layers due to the compounding of the water phase antioxidant and the oil phase antioxidant, thereby greatly improving the stability of the microcapsule.)

1. The preparation method of the vitamin A microcapsule is characterized by comprising the following steps:

1) adding protective colloid, filler, water-phase antioxidant, oil-phase antioxidant, cross-linking agent and emulsifier into pure water, heating until the protective colloid, filler, water-phase antioxidant, oil-phase antioxidant, cross-linking agent and emulsifier are completely dissolved to form water-soluble colloid, adding chitosan adsorbent into the water-soluble colloid, sending the mixture into a sand mill, and then cooling to a certain temperature for circular grinding for later use;

2) slowly adding vitamin A crystals into the water-soluble colloid to be ground in the step 1), and continuously grinding in a sand mill until nano-scale emulsion with the emulsion particle size of less than 200nm is formed;

3) drying and granulating, fluidizing and drying, screening and crosslinking the nano-scale emulsion obtained in the step 2) to obtain the stable vitamin A microcapsule.

2. The method according to claim 1, wherein the protective colloid is selected from any one or more of gelatin, fish gelatin, gum arabic, xanthan gum, modified starch, and lignosulfonate; preferably gelatin, wherein the gelatin is porcine gelatin, the freezing force is 50-250bloom, and preferably 100-200 bloom.

3. The preparation method according to claim 1 or 2, wherein the filler is any one or more of maltodextrin, syrup, maltooligosaccharide, glucose and fructose; preferably glucose and/or fructose.

4. The preparation method according to any one of claims 1 to 3, wherein the oil-phase antioxidant is selected from any one or more of dibutyl hydroxy toluene (BHT), Butyl Hydroxy Anisole (BHA), tert-butyl hydroquinone (TBHQ), ethoxy quinoline and tocopherol; preferably ethoxyquinoline and/or BHT; the water-phase antioxidant is selected from any one or more of vitamin C, vitamin C sodium salt and vitamin C palmitate.

5. The preparation method according to claim 1 to 4, wherein the cross-linking agent is selected from any one or more of sodium acetate, sodium dihydrogen phosphate and disodium hydrogen phosphate; preferably, the emulsifier is selected from one or more of sucrose fatty acid ester, tween 60, tween 80, polyglycerol stearate and propylene glycol fatty acid ester.

6. The method according to claims 1 to 5, wherein the temperature of the temperature rise in step 1) is 60 to 100 ℃, preferably 60 to 80 ℃; the temperature for reducing the temperature is 30-55 ℃, and preferably 40-50 ℃.

7. The production method according to any one of claims 1 to 6,

the using amount of the pure water is controlled to be 30-60% of the solid content of the emulsion, and preferably 35-50%;

the mass ratio of the protective colloid to the filler is 1-10: 1, preferably 4-6: 1;

the mass ratio of the protective colloid to the cross-linking agent is 10-100: 1, preferably 40-80: 1;

the mass ratio of the vitamin A crystals to the emulsifier is 20-500: 1, preferably 50-200: 1;

the mass ratio of the vitamin A crystals to the protective colloid is 0.5-2: 1, preferably 0.8-1.2: 1;

the mass ratio of the vitamin A crystals to the oil-phase antioxidant is 1-200: 1, preferably 10-50: 1;

the mass ratio of the vitamin A crystal to the water-phase antioxidant is 1-200: 1, preferably 30-100: 1.

8. The method according to any one of claims 1 to 7, wherein the grinding conditions of the sand mill are as follows: the pressure is 0.5-1.5 MPa, the rotating speed is 1000-3000 rmp, and the temperature is 40-50 ℃.

9. The method according to any one of claims 1 to 8, wherein the spray granulation tower is filled with starch having a particle size of < 100 μm at a temperature of 0 to 50 ℃, preferably 10 to 20 ℃.

10. The preparation method according to any one of claims 1 to 9, wherein the fluidized bed drying temperature is 50 to 90 ℃ and the time is 3 to 6 hours; preferably, the temperature is 60-80 ℃ and the time is 4-5 h.

11. A method according to any one of claims 1 to 10, wherein the product after spray granulation is cross-linked in a fluidised bed at a temperature of from 60 ℃ to 120 ℃, preferably from 70 ℃ to 90 ℃.

Technical Field

The invention belongs to the technical field of preparation of nutritional chemical products, and particularly relates to a preparation method of a vitamin A microcapsule.

Background

Vitamin A is an oil-soluble unsaturated ester, is easy to oxidize and unstable under the conditions of light and oxygen, so that the application range is limited, and the application range can be expanded by preparing the vitamin A into solid powder after microencapsulation. Microencapsulation of vitamin A is usually achieved by mixing and emulsifying vitamin A crystals, an antioxidant and an aqueous solution containing a protective colloid, and then spray-drying the emulsion.

Patent CN1965657A describes a method for preparing vitamin A microcapsules, which comprises adding vitamin A oil into a pre-prepared modified starch solution, dispersing and emulsifying at a high speed at 5000-20000 rpm, homogenizing twice at room temperature under 10-40 MPa, and finally centrifuging, spray drying to obtain the vitamin A microcapsules. The obtained product has fine particle size, and is mainly used for flour reinforcement.

Patent CN102198116A discloses mixing vitamin a and antioxidant (vitamin E) under oxygen-free condition, adding 0.1% -0.5% chitosan, stirring for 45 minutes; then filtering through a filter press, filtering to remove chitosan, and obtaining vitamin A oil solution with heavy metals removed fully; and (3) feeding the heavy metal-removed vitamin A oil solution and the octenyl succinic acid starch ester solution into an online emulsifying machine for rapid emulsification, cooling, and finally spray-drying to obtain the vitamin A microcapsule. The patent application innovatively uses chitosan to remove heavy metals in vitamin a to increase the stability of vitamin a microcapsules.

The patent technology adopts the method of high-speed shearing emulsification and high-pressure homogenization, and then the vitamin A microcapsule is prepared by spray drying, the batch operation time in the emulsification process is long, the temperature of the shearing part is high during emulsification, the vitamin A is easy to deteriorate, and the energy consumption is high; and emulsion is easy to be layered after emulsification, so that the embedding effect and stability of a final product are influenced.

Patents CN101513394A and CN 101513394B describe a method for preparing a continuous nano-dispersed vitamin a microcapsule, which comprises grinding vitamin a crystals, an antioxidant and a solvent together to prepare a vitamin a dispersion, heating and dissolving the vitamin a dispersion by a preheater with a pump, cooling, passing through a supergravity rotary packed bed emulsifier to obtain a nano-dispersed vitamin a solution, and spray-drying to obtain the vitamin a microcapsule. The emulsifying effect of the supergravity rotating packed bed emulsifier adopted by the method is not as good as that of a high-shear emulsifying machine, the prepared microcapsule has poor hydrophobicity, and the isomerization and loss of vitamin A under the high-temperature condition are easily caused by heating and dissolving.

Disclosure of Invention

The invention aims to provide a preparation method of vitamin A microcapsules, which is simple and convenient to operate, good in embedding effect and stability and high in bioavailability, aiming at the defects of the existing vitamin A microcapsule production technology.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a preparation method of vitamin A microcapsules comprises the following steps:

1) adding protective colloid, filler, water-phase antioxidant, oil-phase antioxidant, cross-linking agent and emulsifier into pure water, heating until the protective colloid, filler, water-phase antioxidant, oil-phase antioxidant, cross-linking agent and emulsifier are completely dissolved to form water-soluble colloid, adding chitosan adsorbent into the water-soluble colloid, sending the mixture into a sand mill, and then cooling to a certain temperature for circular grinding for later use;

2) slowly adding vitamin A crystals into the water-soluble colloid to be ground in the step 1), and continuously grinding in a sand mill until nano-scale emulsion with the emulsion particle size of less than 200nm is formed;

3) drying and granulating, fluidizing and drying, screening and crosslinking the nano-scale emulsion obtained in the step 2) to obtain the stable vitamin A microcapsule.

In a particular embodiment, the protective colloid is selected from any one or more of gelatin, fish gelatin, gum arabic, xanthan gum, modified starch, lignosulfonate; preferably gelatin, wherein the gelatin is porcine gelatin, the freezing force is 50-250bloom, and preferably 100-200 bloom.

In a specific embodiment, the bulking agent is any one or more of maltodextrin, syrup, malto-oligosaccharide, glucose and fructose; preferably glucose and/or fructose.

In a specific embodiment, the oil-phase antioxidant is selected from any one or more of dibutyl hydroxy toluene (BHT), Butyl Hydroxy Anisole (BHA), tert-butyl hydroquinone (TBHQ), ethoxy quinoline and tocopherol; preferably ethoxyquinoline and/or BHT; the water-phase antioxidant is selected from any one or more of vitamin C, vitamin C sodium salt and vitamin C palmitate.

In a specific embodiment, the cross-linking agent is selected from any one or more of sodium acetate, sodium dihydrogen phosphate and disodium hydrogen phosphate; preferably, the emulsifier is selected from one or more of sucrose fatty acid ester, tween 60, tween 80, polyglycerol stearate and propylene glycol fatty acid ester.

In a specific embodiment, the temperature for raising the temperature in the step 1) is 60-100 ℃, and preferably 60-80 ℃; the temperature for reducing the temperature is 30-55 ℃, and preferably 40-50 ℃.

In a particular embodiment of the process of the present invention,

the using amount of the pure water is controlled to be 30-60% of the solid content of the emulsion, and preferably 35-50%;

the mass ratio of the protective colloid to the filler is 1-10: 1, preferably 4-6: 1;

the mass ratio of the protective colloid to the cross-linking agent is 10-100: 1, preferably 40-80: 1;

the mass ratio of the vitamin A crystals to the emulsifier is 20-500: 1, preferably 50-200: 1;

the mass ratio of the vitamin A crystals to the protective colloid is 0.5-2: 1, preferably 0.8-1.2: 1;

the mass ratio of the vitamin A crystals to the oil-phase antioxidant is 1-200: 1, preferably 10-50: 1;

the mass ratio of the vitamin A crystal to the water-phase antioxidant is 1-200: 1, preferably 30-100: 1.

In a specific embodiment, the sand mill grinding conditions are: the pressure is 0.5-1.5 MPa, the rotating speed is 1000-3000 rmp, and the temperature is 40-50 ℃.

In a specific embodiment, the spray granulation tower is filled with starch, the grain diameter of the starch is less than 100 microns, and the temperature is 0-50 ℃, preferably 10-20 ℃.

In a specific embodiment, the drying temperature of the fluidized bed is 50-90 ℃, and the drying time is 3-6 h; preferably, the temperature is 60-80 ℃ and the time is 4-5 h.

In a particular embodiment, the product after spray granulation is crosslinked in a fluidized bed at a temperature of 60 to 120 ℃, preferably 70 to 90 ℃.

Compared with the prior art, the method has the following outstanding effects:

1) the VA microcapsule is prepared by using the sand mill, vegetable oil and high-temperature dissolved vitamin A are not used, the isomerization and loss of the vitamin A in the high-temperature dissolving process are avoided, the particle size of the emulsion prepared by using the sand mill can reach below 200nm, and the bioavailability and the stability of the emulsion are greatly improved.

2) Because Fe may exist in the water-soluble wall material³⁺、Cu²⁺、Al³⁺The metal ions have larger influence on the stability of the vitamin A, so that the chitosan is used for adsorption before the vitamin A is added, and the chitosan is preferably subjected to impurity removal treatment first, so that the stability and the safety of subsequent vitamin A microcapsules are improved.

3) The method adopts the compounding of the water phase antioxidant and the oil phase antioxidant, the water phase antioxidant plays a layer of antioxidant effect outside the microcapsule, the oil phase antioxidant permeates the inside of the microcapsule, and the VA is protected by the double layers, so that the stability of the microcapsule is greatly improved.

Detailed Description

The method according to the invention will be further illustrated by the following examples, but the invention is not limited to the examples listed, but also encompasses any other known modification within the scope of the claims of the invention.

Examples main raw material sources:

vitamin a crystals obtained by the preparation method of example 1 in patent CN 110950791A;

gelatin, available from rosinolo ltd;

starch: white wave starch, ltd;

modified starch: jaceau starch;

the other reagents are all general chemical pure reagents sold in the market.

The main analytical method and apparatus:

and (3) liquid chromatography characterization: agilent 1260 type liquid chromatograph, chromatographic column Sphersorb C18 columnAn ultraviolet visible light splitting detector Hitachi L7420, a chromatographic workstation data processing system Chomatopdc C-RIA and a stationary phase Zorbax-SIL. Chromatographic conditions are as follows: the mobile phase was a methanol/acetonitrile 9/1(v/v) mixture, the detection temperature was 40 ℃, the flow rate was 1mL/min, and the wavelength was 455 nm. And carrying out qualitative and quantitative analysis on the composition of the product.

A sand mill: shanghai Nuo grinding equipment, wherein the working pressure is set to be 1MPa, and the rotating speed is set to be 2000 rmp;

a high-pressure homogenizing pump: shanghai Donghua homogenizer works;

a spray drying tower: febuxostat, leiste drying equipment, ltd;

laser particle tester: sesbane technologies Inc.

Content of vitamin a: GB/T7292-1999 vitamin A acetate particle as feed additive is used for detection;

surface oil content ═ VA content dissolved in n-hexane/microcapsule VA content × 100%;

the embedding rate is (1-surface oil content) × 100%;

retention rate-final content/initial content 100%.

Example 1

1) Adding 5.0kg of gelatin (120bloom), 1.0kg of glucose, 0.28g of BHT, 0.18kg of vitamin C palmitate, 0.08kg of sodium acetate and 0.06kg of propylene glycol fatty acid ester into 14.8kg of pure water, heating to 70 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 50 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 180 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 15 ℃ for granulation, and obtaining about 12.5Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 4 hours by using hot air at 60 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 11.2Kg of vitamin A microcapsules with the water content of 1.6 percent.

The content of vitamin A in the product is 37.2% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 35.0 percent, and the retention rate of the vitamin A is 94.09 percent.

Example 2

1) Adding 5.5kg of gelatin (50bloom), 1.38kg of fructose, 5.5g of BHT, 0.06kg of vitamin C, 0.07kg of sodium acetate and 0.03kg of polyglycerol stearate into 33.5kg of pure water, heating to 60 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 30 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 160 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 50 ℃ for granulation, and obtaining about 18.6Kg of vitamin A microcapsules with the water content of 5.1 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 3 hours by using hot air at the temperature of 80 ℃, transferring the vitamin A microcapsules into screens of 20 meshes and 120 meshes for screening, transferring particles between 20 meshes and 120 meshes into a cross-linking fluidized bed at the temperature of 60 ℃ for cross-linking for 4 hours, and finally obtaining 16.8Kg of vitamin A microcapsules with the water content of 1.6 percent.

The content of vitamin A is 25.0% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 23.9 percent, and the retention rate of the vitamin A is 95.74 percent.

Example 3

1) Adding 6.88kg of gelatin (250bloom), 1.15kg of syrup, 0.11g of ethoxyquinoline, 0.18kg of sodium ascorbate, 0.17kg of disodium hydrogen phosphate and 0.11kg of sucrose fatty acid ester into 32.9kg of pure water, heating to 100 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 50 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 160 nm;

3) continuously atomizing the vitamin A emulsion, spraying the emulsion at 0 ℃ into a starch bed for granulation, and obtaining about 14.6Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 5 hours by using hot air at 90 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 13.1Kg of vitamin A microcapsules with the water content of 1.8 percent.

The content of vitamin A is 31.9% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 30.2 percent, and the retention rate of the vitamin A is 94.6 percent.

Example 4

1) Adding 4.58kg of lignosulfonate, 1.15kg of malto-oligosaccharide, 0.18g of tocopherol, 0.11kg of sodium ascorbate, 0.11kg of sodium dihydrogen phosphate and 0.04kg of tween-80 into 14.3kg of pure water, heating to 80 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 55 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 150 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 15 ℃ for granulation, and obtaining about 12.1Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 3 hours by using hot air at the temperature of 80 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a 120 ℃ cross-linking fluidized bed for cross-linking for 1 hour, and finally obtaining 10.9Kg of vitamin A microcapsules with the water content of 1.5 percent.

The content of vitamin A is 38.5% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 36.8 percent, and the retention rate of the vitamin A is 95.47 percent.

Example 5

1) Adding 5.0kg of modified starch, 6.0g of xanthan gum, 1.83kg of maltodextrin, 0.55g of tert-butyl hydroquinone (TBHQ), 0.06kg of sodium ascorbate, 0.11kg of sodium acetate and 0.01kg of Tween 60 into 12.7kg of pure water, heating to 70 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 40 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 160 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 15 ℃ for granulation, and obtaining about 19.7Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 6 hours by using hot air at 60 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 17.7Kg of vitamin A microcapsules with the water content of 1.5 percent.

The content of vitamin A is 23.6% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 22.8 percent, and the retention rate of the vitamin A is 96.57 percent.

Example 6

1) Adding 6.88kg of Arabic gum, 1.15kg of maltodextrin, 0.03g of tert-butyl hydroquinone (TBHQ), 5.5kg of sodium ascorbate, 0.07kg of sodium acetate and 0.28kg of Tween 60 into 19.4kg of pure water, heating to 70 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 40 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 160 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 15 ℃ for granulation, and obtaining about 20.0Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 6 hours by using hot air at 60 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 18.0Kg of vitamin A microcapsules with the water content of 1.5 percent.

The content of vitamin A is 23.2% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 21.9 percent, and the retention rate of the vitamin A is 94.37 percent.

Example 7

1) Adding 2.75kg of gelatin (250bloom), 0.69kg of syrup, 0.11g of Butylated Hydroxyanisole (BHA), 0.18kg of sodium ascorbate, 0.07kg of disodium hydrogen phosphate and 0.11kg of sucrose fatty acid ester into 9.4kg of pure water, heating to 70 ℃ for complete dissolution, feeding the mixture into a sand mill through a chitosan adsorbent with the mass 2 times that of the emulsion, and cooling to 45 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), and continuously grinding in a sand mill, wherein the particle size of the emulsion is 160 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 0 ℃ for granulation, and obtaining about 9.7Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 5 hours by using hot air at 70 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 8.8Kg of vitamin A microcapsules with the water content of 1.8 percent.

The content of vitamin A in the product is 47.8% by HPLC analysis, and the embedding rate is 99.9%. After being stored for 1 year at normal temperature, the content is 45.6 percent, and the retention rate of the vitamin A is 95.35 percent.

Comparative example 1

1) Under the protection of nitrogen, 5.5kg of vitamins and 0.28g of BHT are dissolved at 65 ℃;

2) adding 5.0kg of gelatin (120bloom), 1.0kg of glucose, 0.18kg of vitamin C palmitate, 0.08kg of sodium acetate and 0.06kg of propylene glycol fatty acid ester into 14.8kg of pure water, and heating to 70 ℃ for complete dissolution;

3) slowly adding the molten oil obtained in the step 1) into the water phase obtained in the step 2), and shearing at a high speed of 65 ℃ for 20min to obtain emulsion with the particle size of 1.5 mu m;

4) continuously atomizing the vitamin A emulsion and spraying into a starch bed at 15 ℃ for granulation, and obtaining about 12.1Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 4 hours by using hot air at 60 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 10.3Kg of vitamin A microcapsules with the water content of 1.7 percent.

The content of vitamin A is 35.3% and the embedding rate is 99.5% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 31.2 percent, and the retention rate of the vitamin A is 88.28 percent.

Comparative example 2

Compared with the example 2, the process is completely the same except that the aqueous phase antioxidant vitamin C is not added, and 16.7Kg of vitamin A microcapsules with the water content of 1.6 percent are finally obtained.

The content of vitamin A is 23.8% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 20.9 percent, and the retention rate of the vitamin A is 87.86 percent.

Comparative example 3

Compared with the example 3, the sand mill does not add the chitosan adsorbent, and other process conditions are completely the same, and 13.0Kg of vitamin A microcapsules with the water content of 1.8 percent are finally obtained.

The content of vitamin A in the product is 28.8% by HPLC analysis, and the embedding rate is 99.9%. After being stored for 1 year at normal temperature, the content is 23.0 percent, and the retention rate of the vitamin A is 79.91 percent.

Comparative example 4

Compared with the example 3, the oil phase antioxidant ethoxyquinoline is not added, other process conditions are completely the same, and 13.0Kg of vitamin A microcapsules with the water content of 1.8 percent are finally obtained.

The content of vitamin A in the product is 29.6% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 24.1 percent, and the retention rate of the vitamin A is 81.42 percent.

Comparative example 5

1) Adding 6.88kg of gelatin (250bloom), 1.15kg of syrup, 0.11g of ethoxyquinoline, 0.18kg of sodium ascorbate, 0.17kg of disodium hydrogen phosphate and 0.11kg of sucrose fatty acid ester into 32.9kg of pure water, heating to 100 ℃ for complete dissolution, cooling to 50 ℃ for circulation;

2) slowly adding 5.5kg of vitamin A crystals into the protective colloid in the step 1), continuously grinding in a sand mill, and stopping grinding until the particle size of the emulsion reaches 500 nm;

3) continuously atomizing the vitamin A emulsion and spraying into a starch bed for granulation, and obtaining about 14.5Kg of vitamin A microcapsules with the water content of 6.5 percent after 1 hour. Transferring the wet vitamin A microcapsules into a fluidized bed, carrying out fluidized drying for 4 hours by using hot air at 60 ℃, transferring the vitamin A microcapsules into 20-mesh and 120-mesh screens for screening, transferring particles between 20 and 120 meshes into a cross-linking fluidized bed at 85 ℃ for cross-linking for 4 hours, and finally obtaining 13.0Kg of vitamin A microcapsules with the water content of 1.8 percent.

The content of vitamin A is 31.9% and the embedding rate is 99.9% by HPLC analysis. After being stored for 1 year at normal temperature, the content is 27.3 percent, and the retention rate of the vitamin A is 85.52 percent.

While the present invention has been described in detail with reference to the preferred embodiments, it should be understood that the above description should not be taken as limiting the invention. It will be appreciated by those skilled in the art that modifications or adaptations to the invention may be made in light of the teachings of the present specification. Such modifications or adaptations are intended to be within the scope of the present invention as defined in the claims.