A method for preparing β-carotene microcapsules

Abstract

The present invention discloses a preparation method of a novel β-carotene microcapsule. During the preparation of the β-carotene emulsion, a certain content of emulsification auxiliary is added to the formula. The emulsification auxiliary will adsorb on the surface of the β-carotene emulsion droplets. By means of emulsification, electrostatic adsorption and steric hindrance effects, the emulsion droplets are made independent of each other, the stability of the emulsion is increased, so that the emulsion droplets are not easily damaged during the spray drying process of the β-carotene emulsion, the loss of β-carotene during spray drying is reduced, and the storage stability of the β-carotene microcapsule product is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of β-carotene preparations and relates to a method for preparing a novel β-carotene microcapsule. Background Art

[0002] β-carotene (C 40 H 56 ) is an orange-yellow fat-soluble carotenoid. β-carotene can be used as a nutritional and coloring additive. β-carotene is a non-toxic, safe and nutritious food additive recognized by the Joint FAO / WHO Expert Committee on Food Additives. Currently, it has been approved for use in 52 countries and regions around the world. β-carotene is a nutrient. After entering the body, through the action of enzymes in the liver and small intestinal mucosa, 50% of it becomes vitamin A, which has the effect of tonifying the liver and improving eyesight, can treat night blindness, promote digestion and relieve constipation, and its conversion is adjustable, so it will not cause vitamin A cumulative poisoning due to excessive ingestion. β-carotene is widely used in the food industry, feed industry, medicine and cosmetics industry. β-carotene is fat-soluble, and its dosage forms are usually in the form of capsules and gels.

[0003] β-carotene should be protected from oxidation during application. Since β-carotene has many double-bond structures, it is prone to isomerization under the action of heat, ions and light, and is prone to oxidation when exposed to oxygen. Moreover, in addition to factors such as oxygen, light and heat, antioxidants, metal ions, pH value, etc. also have an impact on the stability of β-carotene. Therefore, when using β-carotene, oxygen, light, high temperature, etc. should be isolated as much as possible, and at the same time, embedding technology is used to solve this problem, embedding β-carotene in a colloid with relatively low chemical activity and high stability to protect the activity of β-carotene.

[0004] Chinese Patent Publication No. CN 101999577 introduces a method for preparing carotene microcapsule powder. By using ultrasonic high-speed shearing and high-pressure homogenization, an alcohol solution containing β-carotene is mixed with an aqueous phase to prepare a β-carotene emulsion, and a β-carotene emulsion with a particle size of 100-400 nm can be obtained; this method uses alcohol to dissolve β-carotene crystals, with a relatively low solubility, requires a large amount of alcohol, has a certain safety risk during spray drying, and there will be a certain amount of alcohol solvent residue in the product, which is not conducive to downstream applications; and in the formula, gelatin, starch, and β-cyclodextrin are used as emulsifiers, with relatively weak emulsifying ability, and more complex emulsifying equipment is required for emulsification, increasing the equipment cost.

[0005] Chinese published patent CN 113229495 introduced a method for preparing β-carotene double-layer nanoparticles. Using β-carotene oil phase and casein aqueous phase as raw materials, a single-layer nanoemulsion was formed by homogenization, and then compounded with chitosan aqueous solution to form a mixed system. Through dynamic high-pressure microfluidization treatment and drying treatment, a stable particle system with β-carotene encapsulated by a double-wall material was formed. This method uses casein and chitosan to encapsulate β-carotene, protecting the stability of β-carotene. However, the β-carotene raw material used in this method is β-carotene dissolved in triglyceride, and the content of β-carotene in the particles is relatively low, and β-carotene crystal powder cannot be used for formulation.

[0006] Chinese published patent CN 109156827 A discloses a method for preparing β-carotene microcapsules using a grinding device. First, a water-soluble wall material, an antioxidant, and a filler are heated and fully dissolved to form a water-soluble colloid. Then, at low temperature, β-carotene is sheared to be efficiently, rapidly, and uniformly dispersed in the water-soluble colloid. Finally, a β-carotene emulsion is obtained by grinding with a nano-grinder. No organic solvents are used in the whole process of this method, and the process is green and environmentally friendly, which is more conducive to food safety. At the same time, this method has no high-temperature process and no solvent residue, avoiding the cis-trans isomerization of β-carotene, and greatly improving its bioavailability and safety. However, this method only uses a grinder for cyclic grinding, with low grinding efficiency and long grinding time, which cannot meet the industrial requirements.

[0007] Chinese published patent CN108433013A discloses a method for preparing a natural carotene preparation using a composite emulsifier. The composite emulsifier of lecithin, medium-chain triglyceride, and Tween 80 is used to stabilize the emulsion, and the use of organic solvents is avoided, enabling better dispersion of carotene powder in the aqueous dispersant. However, Tween 80 emulsifier is used in the emulsion to increase the emulsification effect. The lipophilic components in Tween 80 include unsaturated fatty acids, and these unsaturated fatty acids are very easy to oxidize and degrade to produce more toxic components. The toxic and side effects generated therefrom will exceed the benefits brought by the product itself. Therefore, the use of organic emulsifiers should be minimized in food additives.

[0008] There are corresponding defects in the above-mentioned methods. In the preparation process of the present invention, a certain amount of emulsifying aid is added. The emulsifying aid is obtained by modifying silicon dioxide and is non-toxic and has no side effects on organisms. Moreover, the present invention also improves the addition stage of the emulsifier. First, the emulsifying aid and β-carotene crystals are mixed and ground, so that the emulsifying aid and the crystal powder are better mixed, and the particle size of the crystal powder is smaller, which is beneficial to the preparation of the emulsion. Secondly, the remaining emulsifying aid is added in the emulsion preparation stage, which can effectively promote the emulsification between the water phase and the powder. By using its electrostatic adsorption ability and steric hindrance effect, the stability of the emulsion is increased, and the emulsion droplets are not easily damaged during the spray drying process of the β-carotene emulsion, reducing the loss of β-carotene during spray drying and improving the storage stability of the β-carotene microcapsule product. Summary of the Invention

[0009] In view of the above problems existing in the prior art, the present invention provides a new method for preparing vitamin A acetate microcapsules. During the preparation process, a certain content of emulsifying aid is added. By using emulsification, electrostatic adsorption and steric hindrance effects, the emulsion droplets are independent of each other, and the stability of the emulsion is increased, thereby improving the stability of the β-carotene product.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] On the one hand, the present invention provides a method for preparing β-carotene microcapsules, and the preparation method includes the following steps:

[0012] (1) a: Mix β-carotene crystals with part of the emulsifying aid and use a grinding device to grind; b: Mix gum, sugar, part of the emulsifying aid, and water, and use a high-speed shearing device to shear and disperse to form an aqueous solution; c: Add the ground β-carotene crystal powder to the aqueous solution and continue to shear and disperse, and then use a grinding device to grind continuously to obtain a β-carotene emulsion;

[0013] (2) Spray granulate the prepared emulsion using a spray drying tower, and introduce a secondary embedding material into the spray granulation tower for secondary embedding. After drying and screening, a β-carotene microcapsule product is obtained.

[0014] In the present invention, in step (1), the emulsifying aid is selected from modified nano-silicon dioxide, and the preparation method of the modified silicon dioxide includes the following steps: Using the gas-phase precipitation method, a hydrophobic metal compound undergoes gas-phase chemical precipitation on the surface of nano-silicon dioxide in the gas phase to form a hydrophobic coating, and modified nano-silicon dioxide is obtained after the reaction ends;

[0015] In the present invention, the hydrophobic metal compound is ZnS, ZnO, SnS, SnO2, GeS, etc., and preferably ZnS;

[0016] In the present invention, the particle size of the nano-silica, D90, is 20 - 300 nm, preferably 50 - 100 nm;

[0017] In the present invention, the mass ratio of the hydrophobic metal compound to the nano-silica is 1:1 to 1:4; preferably 1:1 to 1:2;

[0018] In the present invention, for the preparation of the modified nano-silica by the gas-phase precipitation method, the reaction temperature is 800 - 2000 °C, preferably 900 - 1800 °C, and the reaction time is 2 - 10 h, preferably 3 - 5 h;

[0019] In the present invention, the particle size of the emulsification aid is 0.02 - 0.5 μm, preferably 0.05 - 0.1 μm.

[0020] In the present invention, in step (1), in step a, the mass ratio of the β-carotene crystal to the emulsification aid is 1000:1 to 5:1, preferably 200:1 to 20:1.

[0021] In the present invention, in step (1), in step b, the colloid is one or more of gelatin, gum arabic, agar, guar gum, xanthan gum, lignin sulfonate, sodium carboxymethyl cellulose, polyacrylamide, sodium caseinate, preferably gelatin. The saccharide is one or more of glucose, sucrose, maltose, maltodextrin, fructose, fructose-glucose syrup, malt syrup, preferably glucose.

[0022] In the present invention, in step (1), in step b, by mass ratio, colloid:saccharide:emulsification aid:water = 0.4 - 0.8:0.2 - 0.6:0.001 - 0.1:1, preferably 0.3 - 0.5:0.2 - 0.4:0.005 - 0.05:1.

[0023] In the present invention, in step (1), in step a, the grinding equipment is selected from a ball mill or a sand mill, preferably a sand mill.

[0024] In the present invention, in step (1), in step b, the high-speed shearing equipment is selected from a high-speed shearer, a colloid mill, an emulsifying head or an emulsifying pump, preferably a high-speed shearer.

[0025] In the present invention, in step (1), in step c, the mass ratio of the ground β-carotene crystal powder to the aqueous solution is 1:10 to 1:25, preferably 1:10 to 1:20;

[0026] In the present invention, in step (1), in step c, the grinding equipment is a sand mill or a series of multiple sand mills in series, preferably a series of multiple sand mills in series. Among them, the sizes of the grinding beads of the sand mill for grinding β-carotene powder and the sand mill for grinding the grinding emulsion are 0.6 - 3 mm and 0.2 - 0.8 mm respectively, preferably 0.6 - 1 mm and 0.4 - 0.6 mm.

[0027] In the present invention, in step (2), the secondary embedding material is selected from one or more of starch, modified starch, aluminum oxide, calcium silicate, sodium aluminosilicate, calcium sulfate, silicon dioxide, etc., preferably a mixture of starch and silicon dioxide, and the mixing mass ratio is 100:1 - 10:2, preferably 50:1 - 10:1; the secondary embedding material enters the spray dryer with the air supply, and the mass ratio of the secondary embedding material to the β-carotene emulsion is 2:1 - 10:1, preferably 3:1 - 6:1.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention uses modified silicon dioxide as an emulsifier, which can effectively avoid the use of organic emulsifiers, and effectively reduces the irritation to the gastrointestinal mucosa caused by the use of organic emulsifiers and the damage to the endocrine environment in animals; the present invention also improves the addition stage of the emulsifier. First, the emulsifying aid and β-carotene crystals are mixed and ground, so that the emulsifying aid and the crystal powder are better mixed, and the particle size of the crystal powder is smaller, which is beneficial to the preparation of the emulsion; secondly, the remaining emulsifying aid is added in the emulsion preparation stage, which can effectively promote the emulsification between the water phase and the powder. Utilizing its electrostatic adsorption ability and steric hindrance effect, the stability of the emulsion is increased, and the emulsion droplets are not easily damaged during the spray drying process of the β-carotene emulsion, reducing the loss of β-carotene during spray drying and improving the storage stability of the β-carotene microcapsule product. Specific Embodiments

[0030] The following details the embodiments of the present invention. The examples are intended to explain the present invention and should not be construed as limiting the present invention. For those not specifying specific techniques or conditions in the examples, they shall be carried out according to the techniques or conditions described in the literature in the field or according to the product specifications.

[0031] The content of β-carotene in the β-carotene microcapsules is tested according to GB / T 34469-2017 "Feed Additive β-Carotene (Chemically Synthesized)".

[0032] Entrapment efficiency = (total content of β-carotene in microcapsules - content of β-carotene on the surface of microcapsules) / total content of β-carotene in microcapsules * 100%

[0033] Raw materials and sources:

[0034] Preparation Example 1

[0035] Weigh 50 g of nano-silica (Huana Precision Industry, particle size D90: 50 - 60 nm) and 25 g of ZnS (Zhejiang Yamei Nano Technology Co., Ltd.), put them into a heating furnace, raise the temperature of the heating furnace to 1700 °C to vaporize ZnS, maintain at 1700 °C for 4 h to make them fully mixed, then cool down to room temperature, and take out the prepared powder, which is the nano-SiO₂-ZnS composite material with a composite material D90 of 65 nm;

[0036] Preparation Example 2

[0037] Weigh 100 g of nano-silica (Huana Precision Industry, particle size D90: 60 - 80 nm) and 75 g of ZnO (Merck Materials), put them into a heating furnace, raise the temperature of the heating furnace to 1800 °C to sublimate ZnO, maintain at 1800 °C for 6 h to make them fully mixed, then cool down to room temperature, and take out the prepared powder, which is the nano-SiO₂-ZnO composite material with a composite material particle size D90 of 100 nm;

[0038] Preparation Example 3

[0039] Weigh 20 g of nano-silica (Huana Precision Industry, particle size D90: 50 - 60 nm) and 20 g of SnS (Merck Materials), put them into a heating furnace, raise the temperature of the heating furnace to 1300 °C to vaporize SnS, maintain at 1300 °C for 2 h to make it fully mixed with silica, then cool down to room temperature, and take out the prepared powder, which is the nano-SiO₂-SnS composite material with a composite material particle size D90 of 75 nm;

[0040] Example 1

[0041] (1) Weigh 90 g of β-carotene crystal powder and 0.9 g of nano-SiO₂-ZnS, mix them evenly, and then grind them using a sand mill. The size of the grinding beads of the sand mill is 0.8 - 1 mm, and the grinding time is 25 min;

[0042] (2) Weigh 350 g of gelatin, 200 g of glucose, 15 g of self-made nano-SiO₂-ZnS, and 700 g of water, put them into a beaker, heat to 55 °C, and shear them evenly using a high-speed shearer and set aside. The rotation speed of the high-speed shearer is set to 9000 r / m, and the shear time is 15 min;

[0043] (3) Under the action of a high-speed shearer, uniformly mix the ground crystals with the aqueous phase, and then grind them using a sand mill. The size of the grinding beads is 0.4 - 0.6 mm, and after grinding for 20 min, a uniform β-carotene emulsion is obtained.

[0044] The particle size of the emulsion was measured by a Bettersize 2600 laser particle size analyzer, and the D(4,3) was 0.152 μm.

[0045] (4) The homogenized emulsion was spray granulated using a spray dryer. The emulsion feed temperature was 63 °C, the rotational speed of the atomizer of the spray dryer was 2000 rpm, and 6000 g of corn starch containing 2% nano-silica was used as the secondary embedding material to obtain the crude β-carotene microcapsules.

[0046] The β-carotene content in the microcapsules was 10.80%. After being stored at room temperature for one year, the β-carotene content was detected to have decreased to 10.68%.

[0047] Example 2

[0048] (1) 60 g of β-carotene crystal powder and 1.2 g of nano-SiO₂-ZnO were weighed and mixed evenly, and then ground using a sand mill. The size of the grinding beads of the sand mill was 1 - 1.2 mm, and the grinding time was 30 min.

[0049] (2) 240 g of gelatin, 150 g of glucose, 9 g of nano-SiO₂-ZnO, and 400 g of water were placed in a beaker, heated to 55 °C, and sheared evenly using a high-speed shearer and set aside. The rotational speed of the high-speed shearer was set at 8000 r / m, and the shearing time was 15 min.

[0050] (3) The ground crystals were uniformly mixed with the aqueous phase under the action of a high-speed shearer, and then ground using a sand mill. The size of the grinding beads was 0.3 - 0.4 mm, and a uniform β-carotene emulsion was obtained after grinding for 10 min.

[0051] The particle size of the emulsion was measured by a Bettersize 2600 laser particle size analyzer, and the D(4,3) was 0.163 μm.

[0052] (4) The homogenized emulsion was spray granulated using a spray dryer. The emulsion feed temperature was 63 °C, the rotational speed of the atomizer of the spray dryer was 2200 rpm, and 4000 g of corn starch containing 10% nano-aluminum oxide was used as the secondary embedding material to obtain the crude β-carotene microcapsules.

[0053] The β-carotene content in the microcapsules was 10.30%. After being stored at room temperature for one year, the β-carotene content was detected to have decreased to 10.21%.

[0054] Example 3

[0055] (1) Weigh 120 g of β-carotene crystal powder and 0.6 g of nano-SiO₂-SnS, mix them evenly, and then grind them using a sand mill. The size of the grinding beads in the sand mill is 1.6 - 1.8 mm, and the grinding time is 50 min;

[0056] (2) Weigh 300 g of gum arabic, 400 g of sucrose, 50 g of nano-SiO₂-SnS, and 1000 g of water, put them into a beaker, heat to 65 °C, and shear them evenly using a colloid mill for later use. The rotation speed of the colloid mill is set to 6000 r / m, and the shearing time is 25 min;

[0057] (3) Uniformly mix the ground crystals with the aqueous phase under the action of a colloid mill, and then grind them using a sand mill. The size of the grinding beads is 0.2 - 0.3 mm. After grinding for 15 min, a uniform β-carotene emulsion is obtained.

[0058] Use a bettersize2600 laser particle size analyzer to measure the particle size of the emulsion, and D(4,3) is 0.143 μm.

[0059] (4) Use a spray dryer to spray granulate the homogenized emulsion. The feeding temperature of the emulsion is 65 °C, the rotation speed of the atomizer of the spray dryer is 2000 rpm, and 6000 g of corn starch containing 30% nano-calcium silicate is used as the secondary embedding material to obtain the crude β-carotene microcapsules;

[0060] The content of β-carotene in the microcapsules is 10.95%. After being stored at room temperature for one year, the content of β-carotene is detected to be reduced to 10.83%.

[0061] Example 4

[0062] (1) Weigh 70 g of β-carotene crystal powder and 4 g of nano-SiO₂-SnO₂, mix them evenly, and then grind them using a sand mill. The size of the grinding beads in the sand mill is 0.6 - 0.8 mm, and the grinding time is 20 min;

[0063] (2) Weigh 250 g of guar gum, 180 g of maltodextrin, 4 g of nano-SiO₂-SnO₂, and 500 g of water, put them into a beaker, heat to 60 °C, and shear them evenly using an emulsifying head for later use. The rotation speed of the emulsifying head is set to 10000 r / m, and the shearing time is 20 min;

[0064] (3) Uniformly mix the ground crystals with the aqueous phase under the action of an emulsifying head, and then grind them using a sand mill. The size of the grinding beads is 0.6 - 0.8 mm. After grinding for 15 min, a uniform β-carotene emulsion is obtained.

[0065] Use a bettersize2600 laser particle size analyzer to measure the particle size of the emulsion, and D(4,3) is 0.175 μm.

[0066] (4) Use a spray dryer to perform spray granulation on the homogenized emulsion. The emulsion feeding temperature is 60 °C, the rotation speed of the atomizer of the spray dryer is 2400 rpm, and 7000 g of modified starch containing 2% nano-silica is used as the secondary embedding material to obtain crude β-carotene microcapsules;

[0067] The β-carotene content in the microcapsules is 10.93%. After being placed at room temperature for one year, the detected β-carotene content is reduced to 10.80%.

[0068] Example 5

[0069] (1) Weigh 98 g of β-carotene crystal powder and 2.5 g of nano-SiO₂-GeS, mix them evenly, and then use a sand mill for grinding. The size of the grinding beads of the sand mill is 2 - 2.2 mm, and the grinding time is 60 min;

[0070] (2) Weigh 400 g of sodium lignosulfonate, 200 g of fructose syrup, 50 g of nano-SiO₂-GeS, and 500 g of water, put them into a beaker, heat to 60 °C, and use an emulsifying pump to circulate and shear evenly for later use. The rotation speed of the emulsifying head is set to 4000 r / m, and the circulation and shearing time is 20 min;

[0071] (3) Under the action of the emulsifying pump, uniformly mix the ground crystals with the aqueous phase, and then use a sand mill for grinding. The size of the grinding beads is 0.2 - 0.3 mm. After grinding for 20 min, a uniform β-carotene emulsion is obtained.

[0072] Use a bettersize2600 laser particle size analyzer to measure the particle size of the emulsion, and D(4,3) is 0.156 μm.

[0073] (4) Use a spray dryer to perform spray granulation on the homogenized emulsion. The emulsion feeding temperature is 60 °C, the rotation speed of the atomizer of the spray dryer is 2400 rpm, and 3000 g of corn starch containing 4% calcium sulfate is used as the secondary embedding material to obtain crude β-carotene microcapsules;

[0074] The β-carotene content in the microcapsules is 10.40%. After being placed at room temperature for one year, the detected β-carotene content is reduced to 10.28%.

[0075] Comparative Example 1

[0076] Other conditions are the same as those in Example 1, but nano-hydrophobic modified silica is not added in step (1).

[0077] Use a bettersize2600 laser particle size analyzer to measure the particle size of the emulsion, and D(4,3) is 0.359 μm.

[0078] The β-carotene content in the microcapsules is 9.82%. After being stored at room temperature for one year, the β-carotene content is detected to decrease to 9.34%.

[0079] Comparative Example 2

[0080] Other conditions are the same as those in Example 1, but nano-hydrophobic modified silica is not added in step (2).

[0081] The particle size of the emulsion is measured by a bettersize2600 laser particle size analyzer, and D(4,3) is 0.659 μm.

[0082] The β-carotene content in the microcapsules is 9.12%. After being stored at room temperature for one year, the β-carotene content is detected to decrease to 8.24%.

[0083] Comparative Example 3

[0084] Other conditions are the same as those in Example 1, but nano-hydrophobic modified silica is not added in both steps (1) and (2).

[0085] The particle size of the emulsion is measured by a bettersize2600 laser particle size analyzer, and D(4,3) is 1.259 μm.

[0086] The β-carotene content in the microcapsules is 8.56%. After being stored at room temperature for one year, the β-carotene content is detected to decrease to 7.24%.

[0087] Comparative Example 4

[0088] Other conditions are the same as those in Example 1, but nano-hydrophobic modified silica is not added in both steps (1) and (2), and an equal mass of Tween 80 is added in steps (1) and (2) to replace nano-hydrophobic modified silica.

[0089] The particle size of the emulsion is measured by a bettersize2600 laser particle size analyzer, and D(4,3) is 0.235 μm.

[0090] The β-carotene content in the microcapsules is 10.45%. After being stored at room temperature for one year, the β-carotene content is detected to decrease to 9.89%.

[0091] Comparative Example 5

[0092] Other conditions are the same as those in Example 1, but an equal amount of nano-silica is added in both steps (1) and (2) to replace nano-hydrophobic modified silica

[0093] The particle size of the emulsion is measured by a bettersize2600 laser particle size analyzer, and D(4,3) is 0.335 μm.

[0094] The β-carotene content in the microcapsules is 10.25%. After being stored at room temperature for one year, the measured β-carotene content decreased to 9.99%.

Claims

1. A preparation method of β-carotene microcapsules, the preparation method comprising the following steps: (1) a: Mix β-carotene crystals with part of the emulsifying aid and grind using a grinding device; b: Mix gum, sugar, part of the emulsifying aid, and water and shear and disperse using a high-speed shearing device to form an aqueous solution; c: Add the ground β-carotene crystal powder to the aqueous solution and continue to shear and disperse, then continue to grind using a grinding device to obtain a β-carotene emulsion; (2) Spray granulate the prepared emulsion using a spray drying tower, and introduce a secondary embedding material into the spray granulation tower for secondary embedding. After drying and screening, a β-carotene microcapsule product is obtained; The emulsifying aid is selected from modified nano-silica, and the preparation method of the modified silica comprises the following steps: Using the gas-phase precipitation method, a hydrophobic metal compound undergoes gas-phase chemical precipitation on the surface of nano-silica in the gas phase to form a hydrophobic coating. After the reaction, modified nano-silica is obtained; the hydrophobic metal compound is ZnS, ZnO, SnS, SnO2, GeS; in step a, the mass ratio of the β-carotene crystals to the emulsifying aid is 1000:1 to 5:1; in step b, according to the mass ratio, gum: sugar: emulsifying aid: water = 0.4 to 0.8: 0.2 to 0.6: 0.001 to 0.1: 1; in step c, the mass ratio of the ground β-carotene crystal powder to the aqueous solution is 1:10 to 1:

25.

2. The preparation method according to claim 1, characterized in that, The particle size of the nano-silica is D90 of 20 - 300 nm; and / or, the mass ratio of the hydrophobic metal compound to the nano-silica is 1:1 to 1:

4.

3. The preparation method according to claim 2, characterized in that, The particle size of the nano-silica is D90 of 50 - 100 nm; and / or, the mass ratio of the hydrophobic metal compound to the nano-silica is 1:1 to 1:

2.

4. The preparation method according to any one of claims 1 to 3, characterized in that, For the preparation of modified nano-silica by the gas-phase precipitation method, the reaction temperature is 800 - 2000 °C, and the reaction time is 2 - 10 h; and / or, the particle size of the emulsifying aid is 0.02 - 0.5 μm.

5. The preparation method according to claim 4, characterized in that, For the preparation of modified nano-silica by the gas-phase precipitation method, the reaction temperature is 900 - 1800 °C, and the reaction time is 3 - 5 h; and / or, the particle size of the emulsifying aid is 0.05 - 0.1 μm.

6. The preparation method according to any one of claims 1-3, characterized in that, In step (1), in step a, the mass ratio of the β-carotene crystals to the emulsifying aid is 200:1 to 20:1; and / or, in step a, the grinding device is selected from a ball mill or a sand mill.

7. The preparation method according to any one of claims 1 to 3, characterized in that, In step (1), in step b, the gum is one or more of gelatin, arabic gum, agar, guar gum, xanthan gum, lignosulfonate, sodium carboxymethylcellulose, sodium caseinate; the sugar is one or more of glucose, sucrose, maltose, maltodextrin, fructose, fructose-glucose syrup, malt syrup.

8. The preparation method according to any one of claims 1-3, characterized in that, In step (1), in step b, according to the mass ratio, gum: sugar: emulsifying aid: water = 0.3 - 0.5: 0.2 - 0.4: 0.005 - 0.05:

1.

9. The preparation method according to any one of claims 1-3, characterized in that, In step (1), in step c, the mass ratio of the ground β-carotene crystal powder to the aqueous solution is 1:10 to 1:

20.

10. The preparation method according to any one of claims 1-3, characterized in that, In step (1), in step c, the grinding equipment is a sand mill, and the sizes of the grinding beads for grinding β-carotene powder and the grinding beads for grinding the grinding emulsion in the sand mill are 0.6 - 3 mm and 0.2 - 0.8 mm respectively.

11. The preparation method according to claim 10, characterized in that, In step (1), in step c, the grinding equipment is a multi-stage sand mill in series for grinding.

12. The preparation method according to any one of claims 1-3, characterized in that, In step (2), the secondary embedding material is selected from one or more of starch, modified starch, aluminum oxide, calcium silicate, sodium aluminosilicate, calcium sulfate, and silicon dioxide; the mass ratio of the secondary embedding material to the β-carotene emulsion is 2:1 to 10:

1.

13. The preparation method according to claim 12, characterized in that, In step (2), the mass ratio of the secondary embedding material to the β-carotene emulsion is 3:1 to 6:1.