A method for preparing water-repellent vitamin microcapsules

Abstract

The present invention provides a method for preparing vitamin microcapsules, comprising: embedding a vitamin emulsion, and then cross-linking to obtain vitamin microcapsules. During the preparation process, the quality of the vitamin microcapsule product is measured, and the end point of the cross-linking process is determined, and the quality Q of the vitamin A microcapsule product is calculated and determined by the formula Q=2ηlgT. The preparation method of the vitamin A microcapsule of the present invention can effectively control the cross-linking process through its product quality testing method, avoid the heat loss of vitamins caused by the long cross-linking time of the product and the shortening of the shelf life of the vitamin microcapsule product caused by the short cross-linking time, while reducing energy consumption, saving costs, improving product quality, and meeting downstream needs.

Description

Technical Field

[0001] The invention belongs to the technical field of microcapsule preparations, and in particular relates to a method for preparing water-repellent vitamin microcapsules. Background Art

[0002] Vitamins are essential nutrients for animal growth and play an extremely important role in the growth, development, metabolism, health and reproduction of animal bodies. Vitamin A is a very important member of the vitamin A ester family. It has very important functions in the growth performance, reproductive performance, antioxidant capacity, immune performance, product quality and other aspects of animals and is an important component of animal feed.

[0003] Microcapsule technology is a technology that encapsulates trace substances in polymer films. It is a micro-packaging technology for storing solids, liquids, and gases. Microcapsules can control the release of stored solids, liquids, or gases under certain conditions to achieve specific effects. The embedded substances are called core materials, such as fat-soluble vitamins: vitamins A, D, E, K, carotenoids, etc.; the substances that embed the core materials to achieve microencapsulation are called wall materials, such as gelatin, glucose, fructose, etc.

[0004] In the application process of microcapsule products, people hope that animals can digest and absorb nutrients in designated organs after ingesting them. Therefore, they hope that the microcapsule products have good water repellency. However, they need to be digested and absorbed in the intestine. Excessive water repellency will make the microcapsule products unable to be fully absorbed in the intestine, reducing the bioavailability of the microcapsule products.

[0005] Chinese patent CN87103281A introduces a method for preparing cross-linked fat-soluble vitamin microcapsules. The method introduces that through heat treatment cross-linking technology, microcapsules containing fat-soluble vitamins can be better coated in the dense film formed by cross-linking, but the degree of cross-linking of the microcapsule product is not clearly stated, and the batch stability and product quality of the cross-linked product cannot be effectively guaranteed; and the cross-linking method provided by the method is heat treatment, and the heat treatment temperature is 90-180°C. Too high a temperature is not conducive to effectively reducing the loss of vitamins.

[0006] U.S. Patent No. 2756177A states that the preparation of water-repellent vitamin microcapsules requires cross-linking of gelatin and reducing sugars to produce microcapsule particles that are insoluble in boiling water. However, the cross-linking reaction in this patent uses an electric oven to heat the product for a long time, and there is no mutual movement between the microcapsules, which can easily cause local overheating of the microcapsules, resulting in the loss of vitamin active ingredients and affecting the performance of the microcapsule product.

[0007] Chinese patent CN106622051A introduces a method for fluidized crosslinking of microcapsules, which uses a fluidized bed to post-process vitamin microcapsules. This method uses a gas-fluid with a certain temperature and humidity to crosslink the microcapsules, and then performs rapid heat treatment in the fluidized bed to achieve the purpose of forming a protective film. Although this method uses a fluidized bed to increase particle fluidity and heat utilization efficiency, it does not quantitatively indicate the degree of crosslinking of the microcapsule product and the final product index, which can easily cause vitamins to deteriorate during storage, reduce the effectiveness of the vitamin microcapsules, shorten the shelf life, and affect the downstream application of the vitamin microcapsules.

[0008] The above methods all have corresponding defects. The temperature required for cross-linking is too high, the processing time is too long, the vitamin loss in the cross-linking process is large, and the product quality standard is not clearly stated. It is necessary to find an improved microcapsule preparation method so that the degree of vitamin cross-linking can be controlled, the stability and quality of the microcapsule product can be improved, the loss of vitamins can be effectively reduced, and the effectiveness of the microcapsule product can be ensured. This method needs to save energy, meet downstream needs, and save production costs. Summary of the invention

[0009] In view of the above problems existing in the prior art, the purpose of the present invention is to provide an improved method for preparing vitamin microcapsules. In the process of preparing vitamin microcapsules, the quality of the vitamin microcapsules product is measured, and the end point of the cross-linking process is determined, which mainly includes measuring the turbidity T of the hot water soaking liquid of the vitamin microcapsules and the ratio η of the vitamin content in the hot water soaking liquid of the vitamin microcapsules to the total vitamin content in the vitamin microcapsules, also known as the dissolution rate, and calculating the quality Q of the vitamin microcapsule product by the formula Q=2ηlgT. The preparation method of the vitamin microcapsules of the present invention is cross-linked under specific warm and humid air conditions, and the powdered materials are prevented from absorbing water and bonding by controlling the appropriate hot and humid air conditions. The cross-linking process can be effectively controlled by the product quality testing method, so as to avoid the heat loss of vitamins caused by the long cross-linking time of the product and the shortening of the shelf life of the vitamin microcapsule product caused by the short cross-linking time, and at the same time avoid the energy loss caused by long cross-linking, save costs, improve product quality, and meet downstream needs.

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

[0011] A method for preparing water-repellent vitamin microcapsules comprises the following steps:

[0012] Step 1: Mix vitamins and antioxidants, and heat to dissolve to form an oil phase;

[0013] Step 2: Mixing colloid, sugar and water as the water phase, mixing the water phase and the oil phase, and embedding the oil phase once by shearing and homogenizing to form an emulsion;

[0014] Step 3: spray granulating the emulsion, introducing secondary embedding material for secondary embedding, drying and sieving to obtain crude vitamin microcapsules;

[0015] Step 4: cross-linking the crude vitamin microcapsules using warm and humid air (during the cross-linking process, in order to ensure the stability of the cross-linking process and avoid the loss of vitamins during the long-term cross-linking process, the temperature, humidity and airflow velocity of the warm and humid air are controlled);

[0016] Step 5: Take samples at regular intervals to test product quality, and stop cross-linking when the product is qualified to obtain vitamin microcapsules.

[0017] According to the preparation method of the present invention, in step 1,

[0018] The vitamin is selected from one or more of vitamin A, D, E, K, or their esters; preferably, the vitamin is selected from one or more of vitamin A, D, E, K, vitamin A acetate, and vitamin E acetate;

[0019] The antioxidant is one or more of α-tocopherol, tea polyphenols, butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and ethoxyquinoline;

[0020] The mass ratio of vitamins to antioxidants is 1:0.05-0.5, preferably 1:0.1-0.3;

[0021] The heating temperature is 40 to 70°C, preferably 50 to 65°C.

[0022] According to the preparation method of the present invention, in step 2,

[0023] The colloid is one or more of gelatin, gum arabic, agar, guar gum, xanthan gum, and sodium caseinate, preferably gelatin;

[0024] The sugar is one or more of glucose, sucrose, maltose, maltodextrin, fructose, fructose syrup, and maltose syrup, preferably glucose;

[0025] The mass ratio of colloid, sugar and water is (0.4-0.8):(0.2-0.6):1, preferably (0.3-0.5):(0.2-0.4):1;

[0026] The shear rate is 7000-15000 r / m, preferably 9000-12000 r / m; the homogenization pressure is 10-90 bar, preferably 20-50 bar;

[0027] The heating temperature is 45 to 70°C, preferably 50 to 65°C.

[0028] According to the preparation method of the present invention, in step 3,

[0029] The emulsion is spray granulated using a spray dryer;

[0030] The conditions for spray drying are: the atomizer is a centrifugal atomizer, and the atomizer speed is

[0031] 4000-12000r / m, preferably 4000-6000r / m; using a drying air temperature of 80-130°C, preferably 80-105°C; drying to a moisture content of 2-10wt%, preferably 3-5wt%;

[0032] 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, wherein the mass ratio of starch to silicon dioxide is 100:1 to 5:1, preferably 50:1 to 10:1;

[0033] The mass ratio of the secondary embedding material to the emulsion is 2:1 to 10:1, preferably 3:1 to 6:1.

[0034] According to the preparation method of the present invention, in step 4, using warm and humid air for cross-linking means using hot air containing a certain humidity to make the crude vitamin microcapsules boil and fluidize, promote the reaction between the colloid and sugar in the microcapsule shell, and enhance the water repellency.

[0035] According to the preparation method of the present invention, in step 4, cross-linking is carried out in a boiling fluidized bed.

[0036] According to the preparation method of the present invention, in step 4, the temperature, humidity and air flow rate of the warm and humid air are controlled as follows:

[0037] 0-10min: air humidity increases from 5% to 10-30% at a rate of 0.5-3% / min; air temperature increases from 20°C to 25-60°C at a rate of 0.5-5°C / min; air flow velocity is 5-12m / s;

[0038] 10-20min: air humidity increases from 10-30% to 30-80% at a rate of 1-4% / min; air temperature increases from 25-60°C to 40-90°C at a rate of 0-3°C / min; air flow velocity is 4-10m / s;

[0039] 20min~end: air humidity is maintained at 30~80%; air temperature is maintained at 40~90℃; air flow speed is maintained at 4~10m / s.

[0040] According to the preparation method of the present invention, in step 4, the temperature, humidity and air flow rate of the warm and humid air are controlled as follows:

[0041] 0-10min: air humidity increases from 5% to 10-25% at a rate of 1-2% / min; air temperature increases from 20°C to 40-60°C at a rate of 2-3°C / min; air flow velocity is 6-10m / s;

[0042] 10-20min: air humidity increases from 10-25% to 40-60% at a rate of 2-3% / min; air temperature increases from 40-60°C to 50-80°C at a rate of 1-2°C / min; air flow velocity is 5-8m / s;

[0043] 20min~end: air humidity is maintained at 40~60%; air temperature is maintained at 50~80℃; air flow speed is maintained at 5~8m / s.

[0044] According to the preparation method of the present invention, in step 5, the method of product quality testing is:

[0045] Step a: Soak the vitamin microcapsules in hot water and test the turbidity T;

[0046] Step b: Soaking the vitamin microcapsules in hot water to obtain a hot water soaking solution of the vitamin microcapsules, then using a solvent to extract, separating the organic phase, and measuring the content of the vitamin in the organic phase to obtain the content of the vitamin in the hot water soaking solution of the vitamin microcapsules, and calculating the dissolution rate η of the vitamin according to the following formula I:

[0047]

[0048] Step c: Calculate the product quality Q of the vitamin microcapsules according to the following formula II:

[0049] Q=2ηlgT

[0050] Formula II

[0051] Wherein, η represents dissolution rate and T represents turbidity;

[0052] When Q < 0.8, the vitamin microcapsules are excessively cross-linked;

[0053] When 0.8≤Q≤2, the cross-linking degree of the vitamin microcapsules is qualified and meets the downstream market demand;

[0054] When Q>2, the cross-linking degree of the vitamin microcapsules is low and the storage stability of the vitamin microcapsules is low.

[0055] According to the preparation method of the present invention, in the product quality test of step 5, in step a, the hot water temperature is 80-100° C., preferably 90-100° C.; the mass ratio of the vitamin microcapsules to the hot water is 1:20-1:100; preferably 1:25-1:50.

[0056] According to the preparation method of the present invention, in the product quality test of step 5, in step b,

[0057] The temperature of the hot water is 60-90°C, preferably 70-80°C; the mass ratio of the vitamin microcapsules to the hot water is 1:50-1:200; preferably 1:100-1:150;

[0058] The solvent is methanol or ethanol, preferably ethanol;

[0059] The volume ratio of water to solvent is 1:5 to 1:50, preferably 1:10 to 1:30.

[0060] According to the preparation method of the present invention, in the product quality test of step 5, in step b, when the vitamin is selected from vitamin A acetate, the content of the vitamin is measured according to the method in GB / T7292-1999.

[0061] According to the preparation method of the present invention, in step 5, sampling is performed every 10 to 40 minutes after 20 minutes of cross-linking. For example, sampling is performed every 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, and 40 minutes after 20 minutes of cross-linking, and preferably every 30 minutes.

[0062] Beneficial Effects

[0063] The preparation method of the vitamin microcapsules of the present invention performs cross-linking under specific temperature and humidity air conditions, and avoids water absorption and adhesion of powdered materials by controlling appropriate hot and humid air conditions. The cross-linking process can be effectively controlled through its product quality testing method, and the heat loss of vitamins caused by too long cross-linking time of the product and the shortening of the shelf life of the vitamin microcapsule product caused by too short cross-linking time can be avoided. At the same time, energy loss caused by long-term cross-linking can be avoided, so as to save costs, improve product quality and meet downstream needs. DETAILED DESCRIPTION

[0064] The embodiments of the present invention are described in detail below. The examples of the embodiments are intended to explain the present invention and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the existing literature in the art or the product instructions are used.

[0065] In the following examples, reagents and raw materials not specifically described are all commercially available.

[0066] Turbidity test: Measured using HACH brand TL2300 turbidity meter;

[0067] The preparation of vitamin A acetate is taken as an example below. The vitamin A acetate used in the examples and comparative examples comes from Wanhua Chemical Group Co., Ltd.

[0068] Test method for vitamin A acetate content:

[0069] According to GB / T 7292-1999 "Feed Additive Vitamin A Acetate Microparticles", the content of vitamin A acetate in vitamin A acetate microcapsules and the content of vitamin A acetate in hot water soaking solution of vitamin A acetate microcapsules are tested according to this test method, and the content unit is: IU / g;

[0070] Calculation of dissolution η:

[0071]

[0072] Absorption rate of vitamin A acetate in blood:

[0073] The content of vitamin A acetate in the blood is detected according to the method in GB / T7292-1999, and the ratio of this content to the content of vitamin A acetate added in the feed is the absorption rate.

[0074] Product quality of vitamin microcapsules Q:

[0075] Q=2ηlgT

[0076] Wherein, η represents dissolution rate and T represents turbidity;

[0077] When Q < 0.8, the vitamin microcapsules are excessively cross-linked;

[0078] When 0.8≤Q≤2, the cross-linking degree of the vitamin microcapsules is qualified and meets the downstream market demand;

[0079] When Q>2, the cross-linking degree of the vitamin microcapsules is low and the storage stability of the vitamin microcapsules is low.

[0080] Example 1

[0081] (1) Weigh 35 g of gelatin, 20 g of glucose, and 70 g of water, put them into a container, heat to 50-55° C., and stir evenly to obtain an aqueous phase for later use;

[0082] (2) Weigh 36.2 g of vitamin A acetate and 8 g of α-tocopherol, heat to 59-65° C., add the vitamin A acetate to the aqueous phase prepared in (1) when it is completely melted into a clear and transparent liquid (oil phase), and shear homogenize to obtain an emulsion, wherein the shear speed is 11000 r / m and the homogenization pressure is 40 bar;

[0083] (3) using a spray dryer to spray granulate 169.2 g of the emulsion, the emulsion feed temperature was 63° C., the spray dryer atomizer speed was 4000 rpm, the drying air temperature was 90° C., and 700 g of corn starch containing 4% silicon dioxide was added as a secondary embedding material to obtain a crude vitamin A microcapsule with a water content of 5 wt %;

[0084] (4) The crude vitamin A microcapsules were cross-linked using a boiling fluidized bed. From 0 to 10 min, the air temperature was increased from 20°C to 50°C at a rate of 3°C / min, the air humidity was increased from 5% to 20%RH at a rate of 1.5% / min, and the air velocity was 8 m / s. From 10 to 20 min, the air temperature was increased from 50°C to 60°C at a rate of 1°C / min, the air humidity was increased from 20% to 50%RH at a rate of 3% / min, and the air velocity was 6 m / s. The final temperature was 60°C, the humidity was 50%RH, and the air velocity was 6 m / s.

[0085] When the cross-linking time was 30 min, the turbidity of the product was measured. Using 95°C hot water, the mass ratio of the product to the hot water was 1:25, and the turbidity of the product was 1000 NTU; using 70°C hot water, the mass ratio of the product to the hot water was 1:100, and ethanol was used to extract the vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:10, and the dissolution rate η of the tested product was 80%, and the product quality Q=4.8;

[0086] When the cross-linking time was 60 min, the turbidity of the product was measured. Using 95°C hot water, the mass ratio of the product to hot water was 1:25, and the turbidity of the product was 100NTU. Using 70°C hot water, the mass ratio of the product to hot water was 1:100, and ethanol was used to extract vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:10, the product dissolution rate η was 40%, and the product quality Q=1.6.

[0087] The content of vitamin A acetate in the microcapsule is 1.05 million IU / g (according to the national standard GB / T 7292-1999). After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 80%; after the microcapsule product was placed at room temperature for one year, the vitamin A acetate content was detected to be reduced to 1.042 million IU / g.

[0088] Example 2

[0089] (1) Weigh 50 g of gum arabic, 32 g of fructose, and 110 g of water, put them into a container, heat to 55-60° C., and stir evenly to obtain an aqueous phase for later use;

[0090] (2) Weigh 52.1 g of vitamin A acetate and 12 g of α-tocopherol, heat to 60-62° C., add the vitamin A acetate to the aqueous phase prepared in (1) when it is completely melted into a clear and transparent liquid (oil phase), and shear homogenize to obtain an emulsion, wherein the shear speed is 10,000 r / m and the homogenization pressure is 30 bar;

[0091] (3) using a spray dryer to spray granulate 256.1 g of the emulsion, the emulsion feed temperature was 60° C., the spray dryer atomizer speed was 5000 rpm, the drying air temperature was 105° C., and 1000 g of corn starch containing 2% calcium silicate was added as a secondary embedding material to obtain a crude vitamin A microcapsule with a water content of 4 wt %;

[0092] (4) The crude vitamin A microcapsules were cross-linked using a boiling fluidized bed. From 0 to 10 min, the air temperature was increased from 20°C to 40°C at a rate of 2°C / min, the air humidity was increased from 5% to 25% RH at a rate of 2% / min, and the air velocity was 9 m / s. From 10 to 20 min, the air temperature was increased from 40°C to 50°C at a rate of 1°C / min, the air humidity was increased from 25% to 55% RH at a rate of 3% / min, and the air velocity was 7 m / s. The final temperature was 50°C, the humidity was 55% RH, and the air velocity was 7 m / s.

[0093] When the cross-linking time was 30 min, the turbidity of the product was measured. Using 90°C hot water, the mass ratio of the product to the hot water was 1:30, and the turbidity of the product was 1200 NTU; using 80°C hot water, the mass ratio of the product to the hot water was 1:120, and ethanol was used to extract vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:15, and the dissolution rate η of the tested product was 85%, and the product quality Q=5.23;

[0094] When the cross-linking time was 70 min, the turbidity of the product was measured. Using 90°C hot water, the mass ratio of the product to hot water was 1:30, and the turbidity of the product was 90NTU. Using 80°C hot water, the mass ratio of the product to hot water was 1:120. Ethanol was used to extract vitamin A acetate in the aqueous phase, the volume ratio of water to ethanol was 1:15, the product dissolution rate η was 40%, and the product quality Q=1.56.

[0095] The content of vitamin A acetate in the microcapsule is 1.03 million IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 78%. After the microcapsule product was placed at room temperature for one year, the content of vitamin A acetate was detected to be reduced to 1.012 million IU / g.

[0096] Example 3

[0097] (1) Weigh 37 g sodium caseinate, 19 g fructose syrup, and 80 g water, put them into a container, heat to 56-63° C., and stir evenly to obtain an aqueous phase for later use;

[0098] (2) Weigh 31.6 g of vitamin A acetate and 7 g of α-tocopherol, heat to 55-63° C., add the vitamin A acetate to the aqueous phase prepared in (1) when it is completely melted into a clear and transparent liquid (oil phase), and shear homogenize to obtain an emulsion, wherein the shear speed is 8000 r / m and the homogenization pressure is 40 bar;

[0099] (3) using a spray dryer to spray granulate 174.6 g of the emulsion, the emulsion feed temperature was 62° C., the spray dryer atomizer speed was 6000 rpm, the drying air temperature was 95° C., and 750 g of corn starch containing 5% calcium sulfate was added as a secondary embedding material to obtain a crude vitamin A microcapsule with a water content of 4.5 wt %;

[0100] (4) The crude vitamin A microcapsules were cross-linked using a fluidized bed. From 0 to 10 min, the air temperature was increased from 20°C to 45°C at a rate of 2.5°C / min, the air humidity was increased from 5% to 20%RH at a rate of 1.5% / min, and the air velocity was 8.5 m / s; from 10 to 20 min, the air temperature was increased from 45°C to 60°C at a rate of 1.5°C / min, the air humidity was increased from 20% to 45%RH at a rate of 2.5% / min, and the air velocity was 8 m / s; the final temperature was 60°C, the humidity was 45%RH, and the air velocity was 8 m / s.

[0101] When the cross-linking time was 35 min, the turbidity of the product was measured. Using 100°C hot water, the mass ratio of the product to the hot water was 1:30, and the turbidity of the product was 700 NTU; using 75°C hot water, the mass ratio of the product to the hot water was 1:150, and ethanol was used to extract the vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:20, and the dissolution rate η of the tested product was 70%, and the product quality Q=3.98;

[0102] When the cross-linking time was 65 min, the turbidity of the product was measured. Using 100°C hot water, the mass ratio of the product to hot water was 1:30, and the turbidity of the product was 50 NTU. Using 75°C hot water, the mass ratio of the product to hot water was 1:150. Ethanol was used to extract vitamin A acetate in the aqueous phase, the volume ratio of water to ethanol was 1:20, the product dissolution rate η was 30%, and the product quality Q=1.02.

[0103] The content of vitamin A acetate in the microcapsule is 1.02 million IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 88%. After the microcapsule product was placed at room temperature for one year, the content of vitamin A acetate was detected to be reduced to 1.002 million IU / g.

[0104] Comparative Example 1

[0105] The experimental steps are the same as those in Example 1, except that in step (4), no programmed temperature and humidity changes are set.

[0106] The initial air humidity was 60% RH and the temperature was 70°C, which caused the product to stick as soon as it came into contact with the wet air in the fluidized bed, forming a mass of material accumulation in the dead corner of the fluidized bed, resulting in a 12% decrease in product yield;

[0107] The cross-linking was run for a total of 40 minutes, and the turbidity of the product was measured. Using 95°C hot water, the mass ratio of the product to the hot water was 1:25, and the product turbidity was 30NTU; using 70°C hot water, the mass ratio of the product to the hot water was 1:100, and ethanol was used to extract vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:10, the test product dissolution rate η was 20%, and the product quality Q=0.59.

[0108] The content of vitamin A acetate in the microcapsule is 1.03 million IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 58%. After the microcapsule product was placed at room temperature for one year, the vitamin A acetate content was detected to be reduced to 1.003 million IU / g.

[0109] Comparative Example 2

[0110] The experimental steps are the same as those in Example 1, except that in step (4), the whole process gas velocity is 2 m / s.

[0111] The particle boiling fluidization height was low, and a large amount of material was fluidized at the bottom of the fluidized bed. When the process was carried out for 25 minutes, lumps appeared, resulting in a 18% decrease in product yield;

[0112] The cross-linking was run for 25 minutes. The turbidity of the product was measured. The mass ratio of the product to the hot water was 1:25 at 95°C and the turbidity of the product was 300 NTU. The mass ratio of the product to the hot water was 1:100 at 70°C. Ethanol was used to extract the vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:10. The dissolution rate η of the tested product was 60% and the product quality Q was 2.97.

[0113] The content of vitamin A acetate in the microcapsule is 1.01 million IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 82%. After the microcapsule product was placed at room temperature for one year, the content of vitamin A acetate was detected to be reduced to 903,000 IU / g.

[0114] Comparative Example 3

[0115] The experimental steps are the same as those in Example 1, except that in step (4), the whole process gas velocity is 15 m / s.

[0116] The particle boiling fluidization height is high, and a large amount of material is fluidized at the top of the fluidized bed. Due to the wet air, block accumulation occurs at the top filter screen when the process is carried out for 18 minutes, and the product yield is reduced by 15%;

[0117] The cross-linking was run for 18 minutes. The turbidity of the product was measured. When using 95°C hot water, the mass ratio of the product to the hot water was 1:25, and the turbidity of the product was 1500NTU. When using 70°C hot water, the mass ratio of the product to the hot water was 1:100. Ethanol was used to extract vitamin A acetate in the aqueous phase. The volume ratio of water to ethanol was 1:10. The dissolution rate η of the tested product was 89%, and the product quality Q=5.65

[0118] The content of vitamin A acetate in the microcapsule is 1.03 million IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 95%. After the microcapsule product was placed at room temperature for one year, the content of vitamin A acetate was detected to be reduced to 805,000 IU / g.

[0119] Comparative Example 4

[0120] The experimental steps are the same as those in Example 1, except that in step (4), cross-linking is stopped after only 22 minutes of cross-linking. The turbidity of the product is measured using 95°C hot water with a mass ratio of product to hot water of 1:25, and the turbidity of the product is 900NTU; using 70°C hot water with a mass ratio of product to hot water of 1:100, ethanol is used to extract vitamin A acetate in the aqueous phase, the volume ratio of water to ethanol is 1:10, the dissolution rate η of the tested product is 85%, and the product quality Q=5.02.

[0121] The content of vitamin A acetate in the microcapsules is 997,000 IU / g. After being prepared into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 90%. After being placed at room temperature for one year, the content of vitamin A acetate was detected to be reduced to 929,000 IU / g.

[0122] Comparative Example 5

[0123] The experimental steps are the same as those in Example 1, except that in step (4), cross-linking is stopped after 100 minutes, the turbidity of the product is measured, 95°C hot water is used, the mass ratio of the product to the hot water is 1:25, and the turbidity of the product is 15NTU; 70°C hot water is used, the mass ratio of the product to the hot water is 1:100, and ethanol is used to extract vitamin A acetate in the aqueous phase, the volume ratio of water to ethanol is 1:10, the dissolution rate η of the tested product is 9%, and the product quality Q=0.21.

[0124] The content of vitamin A acetate in the microcapsule is 987,000 IU / g. After being placed at room temperature for one year, the vitamin A acetate content was detected to be reduced to 983,000 IU / g. After the product was configured into feed and fed to chickens for 2 weeks, the absorption rate of vitamin A acetate in the blood was detected to be 20%.

Claims

1. A method for preparing water-repellent vitamin microcapsules, comprising the following steps: Step 1: Mix vitamins and antioxidants, and heat to dissolve to form an oil phase; Step 2: Mixing colloid, sugar and water as the water phase, mixing the water phase and the oil phase, and embedding the oil phase once by shearing and homogenizing to form an emulsion; Step 3: spray granulating the emulsion, introducing secondary embedding material for secondary embedding, drying and sieving to obtain crude vitamin microcapsules; Step 4: cross-linking the crude vitamin microcapsules using warm and humid air; Step 5: Take samples at regular intervals to test product quality, and stop cross-linking when the product is qualified to obtain vitamin microcapsules.

2. The preparation method according to claim 1, wherein In step 1, The vitamin is selected from one or more of vitamin A, D, E, K, or esters thereof; preferably, the vitamin is selected from one or more of vitamin A, D, E, K, vitamin A acetate, vitamin E acetate; and / or The antioxidant is one or more of α-tocopherol, tea polyphenols, butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), and ethoxyquinoline; and / or The mass ratio of vitamins to antioxidants is 1:0.05 to 0.5, preferably 1:0.1 to 0.3; and / or The heating temperature is 40 to 70°C, preferably 50 to 65°C.

3. The preparation method according to claim 1 or 2, wherein In step 2, The colloid is one or more of gelatin, gum arabic, agar, guar gum, xanthan gum, and sodium caseinate; and / or The sugar is one or more of glucose, sucrose, maltose, maltodextrin, fructose, fructose syrup, and maltose syrup; and / or The mass ratio of colloid, sugar and water is (0.4-0.8):(0.2-0.6):1, preferably (0.3-0.5):(0.2-0.4):1; and / or The shear rate is 7000-15000 r / m, preferably 9000-12000 r / m; the homogenization pressure is 10-90 bar, preferably 20-50 bar; and / or The heating temperature is 45 to 70°C, preferably 50 to 65°C.

4. The preparation method according to any one of claims 1 to 3, wherein In step 3, The conditions for spray drying are: a centrifugal atomizer is selected as the atomizer, the atomizer speed is 4000-12000r / m, preferably 4000-6000r / m; the drying air temperature is 80-130°C, preferably 80-105°C; drying to a moisture content of 2-10wt%, preferably 3-5wt%; and / or 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, wherein the mass ratio of starch to silicon dioxide is 100:1 to 5:1, preferably 50:1 to 10:1; and / or The mass ratio of the secondary embedding material to the emulsion is 2:1 to 10:1, preferably 3:1 to 6:

1.

5. The preparation method according to any one of claims 1 to 4, wherein In step 4, The crosslinking is carried out in a boiling fluidized bed; and / or The temperature, humidity and air flow rate of warm and humid air are controlled as follows: 0-10min: air humidity increases from 5% to 10-30% at a rate of 0.5-3% / min; air temperature increases from 20°C to 25-60°C at a rate of 0.5-5°C / min; air flow velocity is 5-12m / s; 10-20min: air humidity increases from 10-30% to 30-80% at a rate of 1-4% / min; air temperature increases from 25-60°C to 40-90°C at a rate of 0-3°C / min; air flow velocity is 4-10m / s; 20min~end: air humidity is maintained at 30~80%; air temperature is maintained at 40~90℃; air flow speed is maintained at 4~10m / s.

6. The preparation method according to any one of claims 1 to 5, wherein In step 4, The temperature, humidity and air flow rate of warm and humid air are controlled as follows: 0-10min: air humidity increases from 5% to 10-25% at a rate of 1-2% / min; air temperature increases from 20°C to 40-60°C at a rate of 2-3°C / min; air flow velocity is 6-10m / s; 10-20min: air humidity increases from 10-25% to 40-60% at a rate of 2-3% / min; air temperature increases from 40-60°C to 50-80°C at a rate of 1-2°C / min; air flow velocity is 5-8m / s; 20min~end: air humidity is maintained at 40~60%; air temperature is maintained at 50~80℃; air flow speed is maintained at 5~8m / s.

7. The preparation method according to any one of claims 1 to 6, wherein In step 5, the method of product quality testing is: Step a: Soak the vitamin microcapsules in hot water and test the turbidity T; Step b: Soaking the vitamin microcapsules in hot water to obtain a hot water soaking solution of the vitamin microcapsules, then using a solvent to extract, separating the organic phase, and measuring the content of the vitamin in the organic phase to obtain the content of the vitamin in the hot water soaking solution of the vitamin microcapsules, and calculating the dissolution rate η of the vitamin according to the following formula I: Step c: Calculate the product quality Q of the vitamin microcapsules according to the following formula II: Q=2ηlgT Formula II Wherein, η represents dissolution rate and T represents turbidity; When Q < 0.8, the vitamin microcapsules are excessively cross-linked; When 0.8≤Q≤2, the cross-linking degree of the vitamin microcapsules is qualified and meets the downstream market demand; When Q>2, the cross-linking degree of the vitamin microcapsules is low and the storage stability of the vitamin microcapsules is low.

8. The preparation method according to claim 7, wherein: In the product quality test of step 5, in step a, the temperature of the hot water is 80-100° C., preferably 90-100° C.; the mass ratio of the vitamin microcapsules to the hot water is 1:20-1:100; preferably 1:25-1:

50.

9. The preparation method according to claim 7 or 8, wherein: In the product quality test of step 5, in step b, The hot water temperature is 60-90°C, preferably 70-80°C; the mass ratio of vitamin microcapsules to hot water is 1:50-1:200; preferably 1:100-1:150; and / or The solvent is methanol or ethanol; and / or The volume ratio of water to solvent is 1:5 to 1:50, preferably 1:10 to 1:

30.

10. The preparation method according to any one of claims 1 to 9, wherein In step 5, sampling is performed every 10 to 40 minutes after 20 minutes of cross-linking.

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