Microcapsule preparation containing origanum vulgare essential oil as well as preparation method and application of microcapsule preparation

Abstract

The invention belongs to the field of animal feed additives, and particularly relates to a microcapsule preparation containing origanum vulgare essential oil as well as a preparation method and application of the microcapsule preparation. The preparation method of the microcapsule preparation containing origanum vulgare essential oil comprises the following steps: S1, dissolving modified beta-cyclodextrin and modified starch in water to obtain a wall material solution; s2, uniformly mixing oregano essential oil to prepare a core material solution, and dissolving an emulsifier in the core material solution to form an oil phase; s3, mixing the wall material solution with an oil phase, and homogenizing to obtain a solution A; and S4, adding a stabilizer into the solution A, uniformly mixing, and spray-drying to obtain the microcapsule preparation containing the origanum vulgare essential oil. The oregano essential oil entrapped microcapsule preparation is prepared by adopting the modified beta-cyclodextrin as a wall material and the modified montmorillonite as a stabilizer, so that the stability and the entrapment efficiency of the oregano essential oil are remarkably improved, the intestinal targeted release of the oregano essential oil is also realized, and the growth and development of animals are promoted.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of animal feed additives, and particularly relates to a microcapsule preparation containing oregano essential oil and a preparation method and application thereof. BACKGROUND

[0002] The main chemical components of oregano essential oil are thymol, carvacrol, terpenes and derivatives thereof, etc., which can significantly inhibit the growth of Staphylococcus aureus, Escherichia coli, Salmonella and ordinary amoebae, effectively regulate the balance of intestinal microflora, improve the intestinal morphology, and also have the effect of promoting the growth of livestock and poultry. However, due to the volatile and chemically unstable nature of the main components, they are easily lost during the processing, storage and use of feed, which greatly limits their practical application effect in animal feed.

[0003] In view of the above technical problems, microencapsulation technology is considered as an effective solution to improve the stability of oregano essential oil and achieve controllable release. The microencapsulation technology not only makes up for the shortcomings of the traditional production method of plant essential oil, but also effectively protects the active ingredients, and is expected to truly achieve the purpose of improving the production performance of livestock and poultry and preventing and treating diseases. The commonly used coating technologies at present mainly include spray drying method, complex coacervation method, etc., but these methods still have obvious deficiencies in practical application, mainly in the aspects of low embedding efficiency, unsatisfactory slow-release effect, lack of intestinal targeting, etc. Therefore, it is urgent to optimize the formula to solve the above problems. SUMMARY

[0004] In order to overcome the deficiencies of the prior art, one of the purposes of the present application is to provide a preparation method of a microcapsule preparation containing oregano essential oil, which is simple in process and helps to realize large-scale industrial production.

[0005] The second purpose of the present application is to provide a microcapsule preparation containing oregano essential oil.

[0006] The third purpose of the present application is to provide an application of a microcapsule preparation containing oregano essential oil.

[0007] One of the purposes of the present application is achieved by adopting the following technical scheme:

[0008] A preparation method of a microcapsule preparation containing oregano essential oil, comprising the following steps:

[0009] S1: dissolving modified beta-cyclodextrin and denatured starch in water to obtain a wall material solution;

[0010] S2: taking oregano essential oil as core material, dissolving emulsifier in the core material to form an oil phase;

[0011] S3: mixing the wall material solution and the oil phase, and homogenizing to obtain a solution A;

[0012] S4: adding the stabilizer in solution A, mixing uniformly, spray drying, to obtain the microcapsule preparation containing oregano essential oil;

[0013] The preparation method of the modified β-cyclodextrin is as follows:

[0014] (1) β-cyclodextrin and amino glycine ethyl ester are dissolved in N-methyl pyrrolidone, heated for reaction, after the reaction is completed, the reaction solution is distilled to obtain a crude product, the crude product is subjected to dialysis and freeze-drying to obtain intermediate 1;

[0015] (2) intermediate 1 and phosphor imidazole are dissolved in water, the pH value is adjusted to 8.0-8.5, heated for reaction, and the modified β-cyclodextrin is obtained after post-treatment.

[0016] In the modified β-cyclodextrin molecule, the phosphate group, the hydrazine group (-NH-NH-), the ester group and the natural hydroxyl group can form a dynamic hydrogen bond crosslinking network through intermolecular force, the network is compact in structure under acidic conditions, and the stability of the microcapsule wall is significantly enhanced. Based on the pH response characteristics of the phosphate group and the ester group: when the microcapsule is in a strong acidic environment (pH is 1-3) in the stomach, the protonation of the phosphate group leads to a decrease in charge density, at the same time, the hydrolysis rate of the ester group is slow, and the hydrogen bond network is completely retained, which effectively inhibits the release of oregano essential oil; and when the microcapsule is in a neutral to weak alkaline intestinal fluid (pH is 6-7.4), the deprotonation of the phosphate group enhances the intermolecular electrostatic repulsion, and the structure is destroyed due to the rapid hydrolysis of the ester group, which together causes the dissociation of the hydrogen bond network, the permeability of the capsule wall is significantly increased, the release of oregano essential oil in the intestine is promoted, and the bioavailability of oregano essential oil in the intestine is improved.

[0017] Further, in step (1), the molar ratio of the β-cyclodextrin and amino glycine ethyl ester is 1:(1-1.2), and the amount ratio of the β-cyclodextrin and N-methyl pyrrolidone is 1 mol:75-100 mL; the heating reaction temperature is 120-130℃, and the time is 6-8h.

[0018] Further, in step (2), the molar ratio of the intermediate 1 and phosphor imidazole is 1:(1-1.2), and the mass concentration of the intermediate 1 in water is 3-5%; the heating reaction temperature is 45-50℃, and the time is 5-8h.

[0019] Further, in step S4, the preparation method of the stabilizer is as follows:

[0020] a. Montmorillonite is dispersed in toluene, after heating, epoxy silane is added, uniformly mixed and heated for reaction, after the reaction is completed, the reaction liquid is filtered, washed and dried to obtain epoxy montmorillonite;

[0021] b.7-hydroxy-4-methoxyisophorone is dissolved in dioxane, and then trihydrogen boron ether is added for alkalization, and then the epoxidized montmorillonite is added for heating reaction, and after the reaction is completed, the reaction solution is filtered, washed and dried to obtain the product.

[0022] Further, in step a, the mass ratio of the montmorillonite and the epoxysilane is 1:(1-1.5), and the mass ratio of the montmorillonite and toluene is 1g:400-500mL; the temperature after heating is 75-80℃; the temperature of the heating reaction is 95-100℃, and the time is 24-28h.

[0023] Further, in step b, the mass ratio of 7-hydroxy-4-methoxyisophorone, epoxidized montmorillonite and dioxane is 1:(0.9-1.2):(5.5-6.5), and the mass ratio of trihydrogen boron ether and 7-hydroxy-4-methoxyisophorone is 1g:50-60μL; the time for alkalization is 1-1.5h; the temperature of the heating reaction is 75-80℃, and the time is 8-10h.

[0024] Further, in step S1, the mass ratio of the modified β-cyclodextrin and the modified starch is 3:(7-10), and the total mass of the modified β-cyclodextrin and the modified starch is 10%-15% of the mass of the wall material solution; the emulsifier is prepared by mixing monoglyceride and sucrose ester according to a mass ratio of 2:(8-10); in step S3, the rotating speed of the homogenizer is 15000-20000rpm, and the time is 3-5min; in step S4, the inlet air temperature of the spray drying is 150-170℃, the outlet air temperature is 70-80℃, and the feeding amount is 5-8mL / min.

[0025] Further, the addition amount of the wall material solution is 50%-100% of the weight of the core material; the addition amount of the emulsifier is 10%-20% of the weight of the core material; and the addition amount of the stabilizer is 2.5%-5% of the weight of the core material.

[0026] The second purpose of the present application is achieved by the following technical scheme:

[0027] A microcapsule preparation containing oregano essential oil is prepared by the preparation method.

[0028] The third purpose of the present application is achieved by the following technical scheme:

[0029] The present application provides an application of a microcapsule preparation containing oregano essential oil in preparing a feed additive.

[0030] The feed additive is a feed additive for promoting the growth of pigs, chickens or aquatic animals and regulating intestinal health.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] The application provides a microcapsule preparation containing oregano essential oil, adopts modified beta-cyclodextrin as a wall material and modified montmorillonite as a stabilizer, and improves the stability and encapsulation rate of the oregano essential oil and realizes intestinal target release of the oregano essential oil.

[0033] (1) Intestinal target release: ester groups and hydrazine groups (-NH-NH-) are introduced on the beta-cyclodextrin through an ester exchange reaction, and phosphoric acid groups are further introduced through the reaction of the hydrazine groups with phosphorimidazoles to obtain modified beta-cyclodextrin, wherein the stability of the phosphoric acid groups is significantly affected by pH: in the acidic environment (pH 1-3) of the stomach, the charge density is low, and the molecular structure is more stable; in the neutral to alkaline intestinal fluid environment (pH 6-7.4), the charge density of the phosphoric acid groups is increased, resulting in a decrease in molecular stability. At the same time, the hydrolysis characteristics of the ester groups also show similar pH dependence: in the gastric juice, the hydrolysis rate of the ester groups is slow; and in the intestinal juice, the hydrolysis rate is significantly accelerated.

[0034] (2) Stability and encapsulation rate: on the one hand, the modified beta-cyclodextrin significantly enhances the binding capacity with the oregano essential oil through -NH-NH-, ester groups and phosphoric acid groups, and the negative charge characteristics of the phosphoric acid groups further strengthen the interaction force between the wall material and the essential oil molecules; on the other hand, the montmorillonite is modified by 7-hydroxy-4-methoxyisophenone (formononetin), the benzene ring structure of the formononetin can form a pi-pi stacking with the aromatic ingredients of the oregano essential oil to improve the adsorption affinity and significantly improve the adsorption capacity for the oregano essential oil; the surface hydrophobicity of the modified montmorillonite is enhanced, and it is easier to adsorb nonpolar essential oil ingredients; the intercalation effect of the formononetin expands the interlayer spacing of the montmorillonite, increasing the effective adsorption sites. The synergistic effect of the two significantly improves the stability and encapsulation rate of the microcapsule preparation containing the oregano essential oil. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The infrared spectrum of the modified montmorillonite obtained in Example 1 of the application. DETAILED DESCRIPTION

[0036] The present application will be described in detail below with reference to embodiments thereof. Various examples are provided by way of explanation of the present application but are not meant as a limitation thereof. In fact, it will be apparent to those skilled in the art that modifications and variations of the present application can be made without departing from the scope or spirit of the present application. For example, features shown or described as part of one embodiment can be used in another embodiment to yield still a further embodiment. It is, therefore, desired to be covered in the present application any modifications and variations included within the scope or spirit of the appended claims and their equivalents. The experimental methods used in the embodiments and comparative examples of the present application are conventional methods unless otherwise specified, and the materials, reagents, etc. used are commercially available unless otherwise specified.

[0037] The preparation method of the oregano essential oil in the embodiments of the present application is as follows: the oregano whole plant is crushed into materials with a particle size of about 1 mm, then 10 times the mass of the crushed oregano whole plant of deionized water is added, then ultrasonic extraction is performed for 30 min, the power of the ultrasonic extraction is set to 400 W; then water vapor distillation is performed, the distillate is collected, and the oregano essential oil is obtained.

[0038] Example 1

[0039] A preparation method of a microcapsule preparation containing oregano essential oil, comprising the following steps:

[0040] S1: modified β-cyclodextrin and modified starch (sodium octenyl succinate starch) are weighed according to a mass ratio of 3:9; the modified β-cyclodextrin and the modified starch are dissolved in water to prepare a wall material solution, wherein the total mass of the modified β-cyclodextrin and the modified starch is 13% of the mass of the wall material solution;

[0041] S2: the monoglyceride and the sucrose ester are mixed according to a mass ratio of 2:9 to prepare an emulsifier; the oregano essential oil is taken as a core material, the emulsifier is dissolved in the core material, the addition amount of the emulsifier is 15% of the weight of the core material, and an oil phase is formed;

[0042] S3: the wall material solution and the oil phase are mixed, the addition amount of the wall material solution is 80% of the weight of the core material, homogenization treatment is performed at 18000 rpm for 4 min, and solution A is obtained;

[0043] S4: a stabilizer is added to the solution A, the addition amount of the stabilizer is 4% of the weight of the core material, uniform mixing is performed at a rotation speed of 250 rpm, spray drying is performed, the inlet air temperature is set to 160°C, the outlet air temperature is set to 75°C, and the feeding amount is set to 7 mL / min, and a microcapsule preparation containing oregano essential oil is obtained.

[0044] The preparation method of the modified β-cyclodextrin is as follows:

[0045]

[0046] (1) Under the conditions of nitrogen protection and reflux, β-cyclodextrin and amino glycine ethyl ester were added into N-methyl pyrrolidone (NMP) to be dissolved thoroughly, the molar ratio of β-cyclodextrin and amino glycine ethyl ester was 1:1.1, and the ratio of the amount of β-cyclodextrin and N-methyl pyrrolidone was 1 mol:90 mL; after being heated to 125°C for 7 h, the solvent was removed by distillation under reduced pressure, the obtained crude product was dialyzed in distilled water for 3 d, and then freeze-dried to obtain intermediate 1;

[0047] Preparation method of intermediate 1 1 HNMR: (C 44 H 74 N2O 36 , 400 MHz, DMSO-d6) δ: 3.28-3.32 (m, 7H), 3.50-3.62 (m, 14H), 3.78-3.82 (m, 6H), 3.88-3.96 (m, 20H), 4.05-4.09 (m, H), 4.20 (s, H), 4.32-4.40 (m, 2H), 4.71 (s, 7H), 4.77 (s, 7H), 4.80 (s, 2H), 5.38-5.42 (m, 7H), 7.85 (s, H). MS (ESI) m / z = 1286.37 [M].

[0048] (2) Intermediate 1 and phosphor imidazole (CAS No.: 15496-31-8) were added into distilled water to be dissolved thoroughly, the mass concentration of intermediate 1 in distilled water was 4%, and the ratio of the amount of intermediate 1 and phosphor imidazole was 1 mol:1.1 mol; the pH value of the solution was adjusted to 8.2 by using 1M NaOH solution, and after being reacted at 48°C for 7 h, the solid product was obtained by precipitation with anhydrous ethanol, and then freeze-dried to obtain modified β-cyclodextrin.

[0049] Preparation method of modified β-cyclodextrin 1 HNMR: (C 44 H 75 N2O 39 P, 400 MHz, DMSO-d6) δ: 3.28-3.32 (m, 7H), 3.50-3.62 (m, 14H), 3.78-3.82 (m, 6H), 3.88-3.96 (m, 20H), 4.05-4.09 (m, H), 4.20 (s, H), 4.32-4.40 (m, 2H), 4.71 (s, 7H), 4.77 (s, 7H), 4.80 (s, 2H), 5.38-5.42 (m, 7H), 7.85 (s, H). MS (ESI) m / z = 1286.37 [M].

[0050] The preparation method of the stabilizer is as follows:

[0051] a. Montmorillonite was dispersed in toluene, and epoxy silane was added at 78°C. The mass ratio of montmorillonite to epoxy silane was 1:1.2, and the volume ratio of montmorillonite to toluene was 1 g:500 mL. After reacting at 100°C under reflux for 24 h, the mixture was filtered, washed with anhydrous ethanol, and dried under vacuum to obtain epoxidized montmorillonite.

[0052] b. Under nitrogen protection, 7-hydroxy-4-methoxyisophenylone was dissolved in dioxane, and alkalized with boron trifluoride ether for 1.5 h. Then, montmorillonite epoxide was added and reacted at 80 °C for 8 h. The mass ratio of 7-hydroxy-4-methoxyisophenylone, montmorillonite epoxide, and dioxane was 1:1:6, and the molar ratio of boron trifluoride ether to 7-hydroxy-4-methoxyisophenylone was 1 g:50 μL. The resulting solution was filtered, washed with anhydrous ethanol, and dried under vacuum to obtain modified montmorillonite.

[0053] The infrared spectrum of modified montmorillonite is as follows: Figure 1 As shown, by Figure 1 It can be seen that, compared to montmorillonite, modified montmorillonite has a higher content of 1725cm. -1 1603cm -1 1257cm -1 The presence of characteristic peaks for C=O, benzene rings, and carbon-silicon bonds indicates that the montmorillonite modification was successful.

[0054] This embodiment also provides a microcapsule formulation containing oregano essential oil, which is prepared using the above-described preparation method.

[0055] Example 2

[0056] A method for preparing a microcapsule formulation containing oregano essential oil includes the following steps:

[0057] S1: Weigh the modified β-cyclodextrin and modified starch (sodium octenyl succinate starch) in a mass ratio of 3:7; dissolve the modified β-cyclodextrin and modified starch in water to prepare a wall material solution, wherein the total mass of the modified β-cyclodextrin and modified starch is 10% of the mass of the wall material solution;

[0058] S2: An emulsifier is prepared by mixing monoglycerides and sucrose esters in a mass ratio of 2:8; using oregano essential oil as the core material, the emulsifier is dissolved in the core material, and the amount of emulsifier added is 10% of the weight of the core material to form an oil phase;

[0059] S3: Mix the wall material solution with the oil phase. The amount of wall material solution added is 50% of the weight of the core material. Homogenize at 15000 rpm for 3 min to obtain solution A.

[0060] S4: Add stabilizer in solution A, the amount of stabilizer is 2.5% of the weight of the core material, mix uniformly at 200 rpm, spray dry, set the inlet temperature to 150℃, the outlet temperature to 70℃, the feeding amount to 5mL / min, to obtain the microcapsule preparation containing oregano essential oil.

[0061] The preparation method of the modified β-cyclodextrin is as follows:

[0062] (1) Under the conditions of nitrogen protection and reflux, β-cyclodextrin and amino glycine ethyl ester are added into NMP for sufficient dissolution, the molar ratio of β-cyclodextrin to amino glycine ethyl ester is 1:1, and the usage ratio of β-cyclodextrin to N-methyl pyrrolidone is 1 mol:75 mL; after heating to 120℃ for 8h, the solvent is removed by distillation under reduced pressure, the obtained crude product is dialyzed in distilled water for 3d, and freeze-drying is performed to obtain intermediate 1;

[0063] (2) Intermediate 1 and phosphorimidazole are added into distilled water for sufficient dissolution, the mass concentration of intermediate 1 in distilled water is 3%, and the usage ratio of intermediate 1 to phosphorimidazole is 1 mol:1 mol; 1M NaOH solution is used to adjust the pH value of the solution to 8.0, and after reaction at 45℃ for 8h, the solid product is obtained by precipitation with anhydrous ethanol and filtration, and freeze-drying is performed to obtain the modified β-cyclodextrin.

[0064] The preparation method of the stabilizer is as follows:

[0065] a. Montmorillonite is dispersed in toluene, and epoxy silane is added at 75℃, the mass ratio of montmorillonite to epoxy silane is 1:1, and the usage ratio of the montmorillonite to toluene is 1g:400 mL; after reaction at 100℃ for 24h under reflux conditions, filtration is performed, anhydrous ethanol is used for washing, and vacuum drying is performed to obtain epoxidized montmorillonite;

[0066] b. Under nitrogen protection, 7-hydroxy-4-methoxyisophenone is dissolved in dioxane, and trifluoroboron ether is added for alkalization for 1h, and then epoxidized montmorillonite is added for reaction at 80℃ for 8h, wherein the mass ratio of 7-hydroxy-4-methoxyisophenone to epoxidized montmorillonite to dioxane is 1:0.9:5.5, and the usage ratio of trifluoroboron ether to 7-hydroxy-4-methoxyisophenone is 1g:55 μL. The solution after reaction is filtered, then washed with anhydrous ethanol, and vacuum dried to obtain modified montmorillonite.

[0067] The embodiment also provides a microcapsule preparation containing oregano essential oil, which is prepared by the above preparation method.

[0068] Example 3

[0069] A preparation method of a microcapsule preparation containing oregano essential oil, comprising the following steps:

[0070] S1: modified β-cyclodextrin and modified starch (sodium octenyl succinate starch) were weighed according to a mass ratio of 3:10; the modified β-cyclodextrin and the modified starch were dissolved in water to prepare a wall material solution, wherein the total mass of the modified β-cyclodextrin and the modified starch was 15% of the mass of the wall material solution;

[0071] S2: a mixture of monoglyceride and sucrose ester was prepared as an emulsifier according to a mass ratio of 2:10; the emulsifier was dissolved in the core material of oregano essential oil, and the addition amount of the emulsifier was 20% of the weight of the core material to form an oil phase;

[0072] S3: the wall material solution was mixed with the oil phase, and the addition amount of the wall material solution was 100% of the weight of the core material, and the solution was homogenized at 20000 rpm for 5 min to obtain solution A;

[0073] S4: the stabilizer was added to the solution A, and the addition amount of the stabilizer was 5% of the weight of the core material, and the solution was mixed uniformly at a speed of 300 rpm, and then was spray dried, and the inlet air temperature was set to 170℃, the outlet air temperature was set to 80℃, and the feeding amount was set to 8 mL / min to obtain the microcapsule preparation containing oregano essential oil.

[0074] The preparation method of the modified β-cyclodextrin is as follows:

[0075] (1) Under the conditions of nitrogen protection and reflux, β-cyclodextrin and amino glycine ethyl ester were added into NMP and dissolved sufficiently, the molar ratio of β-cyclodextrin to amino glycine ethyl ester was 1:1.2, and the ratio of the amount of β-cyclodextrin to N-methyl pyrrolidone was 1 mol:100 mL; after being heated to 130℃ for 6 h, the solvent was removed by distillation under reduced pressure, the obtained crude product was dialyzed in distilled water for 3 d, and freeze-drying was performed to obtain intermediate 1;

[0076] (2) Intermediate 1 and phosphorimidazole were added into distilled water and dissolved sufficiently, the mass concentration of intermediate 1 in the distilled water was 3%, and the ratio of the amount of intermediate 1 to phosphorimidazole was 1 mol:1.2 mol; the pH value of the solution was adjusted to 8.5 by using 1M NaOH solution, and the solution was reacted at 50℃ for 5 h, then the solid product was obtained by precipitation with anhydrous ethanol, and freeze-drying was performed to obtain the modified β-cyclodextrin.

[0077] The preparation method of the stabilizer is as follows:

[0078] a. Montmorillonite was dispersed in toluene, and epoxy silane was added at 80℃, the mass ratio of montmorillonite to epoxy silane was 1:1.5, and the ratio of the amount of the montmorillonite to toluene was 1 g:450 mL; after being reacted at 100℃ under reflux conditions for 24 h, filtration was performed, the product was washed with anhydrous ethanol, and vacuum drying was performed to obtain epoxidized montmorillonite;

[0079] b. Under the protection of nitrogen, 7-hydroxy-4-methoxyisophorone was dissolved in dioxane, and then trifluoroboron diethyl ether was added and alkalized for 1.5 h, and then epoxidized montmorillonite was added, and the reaction was carried out at 80°C for 8 h, wherein the mass ratio of 7-hydroxy-4-methoxyisophorone, epoxidized montmorillonite and dioxane was 1:1.2:6.5, and the dosage ratio of trifluoroboron diethyl ether and 7-hydroxy-4-methoxyisophorone was 1 g:60 μL. The solution after the reaction was filtered, then washed with anhydrous ethanol, and vacuum dried to obtain the modified montmorillonite.

[0080] The present embodiment also provides a microcapsule preparation containing oregano essential oil, which is prepared by the above preparation method.

[0081] Comparative Example 1

[0082] The difference between the present comparative example 1 and example 1 is that the modified β-cyclodextrin is replaced by β-cyclodextrin; and the other conditions are the same as those in example 1.

[0083] Comparative Example 2

[0084] The difference between the present comparative example 2 and example 1 is that the modified montmorillonite is replaced by montmorillonite; and the other conditions are the same as those in example 1.

[0085] Test Example 1

[0086] 1. Test of encapsulation rate:

[0087] 20 mg of the microcapsule preparation obtained in example 1-3 and comparative example 1-2 of the present application was respectively dissolved in 20 mL of a mixed solvent of n-hexane and anhydrous ethanol (the volume ratio of n-hexane and anhydrous ethanol was 8:2), and then ultrasonic broken for 12 min, and treated by oscillation for 3 h, and then centrifuged at a speed of 6000 rpm for 20 min, and the supernatant was diluted to 20 mL, and the absorbance was tested in a UV spectrophotometer, and the total content of oregano essential oil in the microcapsule preparation was calculated.

[0088] Determination of surface oregano essential oil content: 20 mg of the microcapsule preparation obtained in example 1-3 and comparative example 1-2 of the present application was respectively dissolved in 20 mL of a mixed solvent of n-hexane and anhydrous ethanol (the volume ratio of n-hexane and anhydrous ethanol was 8:2), and then gently shaken, and washed for 60 s, and the obtained washing liquid was diluted to 20 mL, and the absorbance was tested in a UV spectrophotometer, and the content of oregano essential oil on the surface of the microcapsule preparation was calculated. The encapsulation rate of oregano essential oil was calculated by the following formula:

[0089] Encapsulation rate (%)=(total oregano essential oil content-surface oregano essential oil content) / total oregano essential oil content×100%.

[0090] Table 1

[0091] Group / Item Embedding rate (%) Example 1 87.74 Example 2 85.52 Example 3 86.21 Comparative Example 1 75.25 Comparative Example 2 71.49

[0092] From the data of Table 1, it can be seen that the embedding rates of the microcapsule preparations of Examples 1-3 of the present application are all maintained at 85% or more. The embedding rates of Comparative Example 1 in which the modified β-cyclodextrin is replaced by β-cyclodextrin and Comparative Example 2 in which the modified montmorillonite is replaced by montmorillonite are both decreased, indicating that the modified β-cyclodextrin and the modified montmorillonite of the present application both work together to improve the embedding rate of the microcapsule preparation.

[0093] 2. In-vitro gastric and intestinal simulated solution release experiment:

[0094] 2.1 The release effect of the microcapsule preparations obtained in Examples 1-3 and Comparative Examples 1-2 of the present application in an in-vitro simulated gastric juice was studied. The microcapsule preparations (100 mg) prepared in each group were placed in a hydrochloric acid solution with a pH of 1.2, and samples were taken at 1 h and 3 h, and the absorbance values were determined; the cumulative release rate (Q W ) was calculated, and the results are recorded in Table 2.

[0095] 2.2 The release effect of the microcapsule preparations obtained in Examples 1-3 and Comparative Examples 1-2 of the present application in an in-vitro simulated intestinal juice was studied. The microcapsule preparations (100 mg) prepared in each group were placed in a sodium phosphate buffer solution with a pH of 7.4, and samples were taken at 1 h, 3 h, 5 h, 7 h, 9 h and 12 h, and the absorbance values were determined; the cumulative release rate (Q C ) was calculated, and the results are recorded in Table 2.

[0096] Table 2 Release effect of the microcapsule preparations in an in-vitro simulated gastric and intestinal juice

[0097]

[0098]

[0099] It can be seen from Table 2 that the cumulative release rates of Examples 1-3 in an in-vitro simulated gastric juice (pH 1.2) are low. Compared with Comparative Examples 1-2, the microcapsule preparations of Examples 1-3 of the present application have excellent sustained-release effect in an in-vitro simulated intestinal juice (pH 7.4). The cumulative release rate of the oregano essential oil obtained in Comparative Example 1 is much lower than that of Example 1. This is because when the microcapsule is in a strong acidic environment in the stomach (pH 1.2), the protonation of the phosphate group leads to a decrease in the charge density, and the hydrolysis rate of the ester group is slow, and the hydrogen bond network is completely preserved, so the release rate of the oregano essential oil is slow; when the microcapsule is in an intestinal juice environment (pH 7.4), the deprotonation of the phosphate group enhances the intermolecular electrostatic repulsion, and the structure is destroyed due to the rapid hydrolysis of the ester group, which together causes the dissociation of the hydrogen bond network, significantly increases the permeability of the capsule wall, and promotes the release of the oregano essential oil in the intestinal tract, thereby improving the bioavailability of the oregano essential oil in the intestinal tract. This provides technical support for the targeted delivery of oregano essential oil to the intestinal environment to exert the functional effect of the essential oil.

[0100] Test Example 2

[0101] 30-day-old piglets with a body weight of 8±0.1 kg were selected and randomly divided into 6 groups, each group having 3 replicates, 10 pigs per replicate, and being set as Example 1 group, Example 2 group, Example 3 group, Comparative Example 1 group, Comparative Example 2 group;

[0102] Example 1 group: 0.1 wt% of the microcapsule preparation of Example 1 was added to the basic diet;

[0103] Example 2 group: 0.1 wt% of the microcapsule preparation of Example 2 was added to the basic diet;

[0104] Example 3 group: 0.1 wt% of the microcapsule preparation of Example 3 was added to the basic diet;

[0105] Comparative Example 1 group: 0.1 wt% of the microcapsule preparation of Comparative Example 1 was added to the basic diet;

[0106] Comparative Example 2 group: 0.1 wt% of the microcapsule preparation of Comparative Example 2 was added to the basic diet;

[0107] The basic diet included the following components in weight percentage: corn 59.0%, soybean meal 10.0%, puffed soybean 14.0%, soybean oil 1.5%, whey powder 5.0%, fermented soybean meal 4.5%, and premix 6%.

[0108] Each 60 g of the premix contained: vitamin A 8000 IU, vitamin B1 4 mg, vitamin B2 3.6 mg, vitamin B5 40 mg, vitamin B6 4 mg, vitamin B12 0.02 mg, vitamin D3 3000 IU, vitamin E 20 IU, vitamin K3 2 mg, biotin 0.15 mg, also 1.0 mg, nicotinic acid 10 mg, D-pantothenic acid 11 mg, copper 10 mg, iron 80 mg, manganese 80 mg, zinc 75 mg, iodine 0.4 mg, selenium 0.30 mg.

[0109] The experiment lasted for 14 days, during which the diarrhea of the piglets was observed every morning at 7 o'clock, the number of piglets with diarrhea per day and the total number of piglets with diarrhea for 14 days were recorded, and the diarrhea rate of the piglets was calculated; diarrhea rate = [total number of piglets with diarrhea / (number of experimental piglets × experimental days)] × 100%.

[0110] Table 3 Effect of microcapsule preparations in different groups on diarrhea rate of piglets

[0111] Group Diarrhea rate (%) Example 1 7.2±2.4 Example 2 8.3±2.1 Example 3 7.6±3.5 Comparative Example 1 18.7±2.7 Comparative Example 2 13.6±4.3

[0112] As can be seen from Table 3, the diarrhea rates of the groups of Examples 1-3 are significantly lower than those of Comparative Examples 1 and 2, indicating that the microcapsule preparation obtained in Examples 1-3 added in the basal diet can promote the release of oregano oil in the intestinal tract, improve the bioavailability of oregano oil in the intestinal tract, reduce the diarrhea rate of piglets, improve the intestinal health of piglets, and be conducive to promoting the growth of piglets.

[0113] The above describes and evaluates some embodiments of the present application. It should be understood that the present application is not limited to the above specific embodiments. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments with the above disclosed methods and technical contents without departing from the scope of the technical solutions of the present application, which does not affect the essential content of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application without departing from the content of the technical solutions of the present application still belongs to the scope of protection of the technical solutions of the present application.

Claims

1. A method for preparing a microcapsule formulation containing oregano essential oil, characterized by, The method comprises the following steps: S1: dissolving modified β-cyclodextrin and modified starch in water to obtain a wall material solution; S2: taking oregano essential oil as a core material, dissolving an emulsifier in the core material to form an oil phase; S3: mixing the wall material solution and the oil phase, and homogenizing to obtain solution A; S4: adding a stabilizer to the solution A, mixing uniformly, and spray drying to obtain a microcapsule preparation containing oregano essential oil; The preparation method of the modified β-cyclodextrin is as follows: (1) dissolving β-cyclodextrin and amino glycine ethyl ester in N-methyl pyrrolidone, heating and reacting, after the reaction is completed, distilling the reaction solution to obtain a crude product, and performing dialysis and freeze-drying on the crude product to obtain intermediate 1; (2) dissolving intermediate 1 and phosphinylimidazole in water, adjusting the pH value to 8.0-8.5, heating and reacting, and performing post-treatment to obtain modified β-cyclodextrin.

2. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 1, characterized in that, In step (1), the molar ratio of the β-cyclodextrin to the amino glycine ethyl ester is 1:(1-1.2), and the amount ratio of the β-cyclodextrin to N-methyl pyrrolidone is 1 mol:75-100 mL; the heating and reaction temperature is 120-130°C, and the time is 6-8h.

3. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 1, characterized in that, In step (2), the molar ratio of intermediate 1 to phosphinylimidazole is 1:(1-1.2), and the mass concentration of intermediate 1 in water is 3-5%; the heating and reaction temperature is 45-50°C, and the time is 5-8h.

4. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 1, characterized by, In step S4, the preparation method of the stabilizer is as follows: a. dispersing montmorillonite in toluene, adding epoxysilane after heating, mixing uniformly, and heating and reacting, after the reaction is completed, filtering, washing and drying the reaction solution to obtain epoxidized montmorillonite; b. dissolving 7-hydroxy-4-methoxyisophenone in dioxane, alkalinizing with boron trifluoride ether, then adding epoxidized montmorillonite to heat and react, after the reaction is completed, filtering, washing and drying the reaction solution.

5. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 4, characterized in that, In step a, the mass ratio of the montmorillonite to the epoxysilane is 1:(1-1.5), and the amount ratio of the montmorillonite to toluene is 1g:400-500mL; the temperature after heating is 75-80°C; the heating and reaction temperature is 95-100°C, and the time is 24-28h.

6. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 4, characterized by, In step b, the mass ratio of 7-hydroxy-4-methoxyisophenone, epoxidized montmorillonite and dioxane is 1:(0.9-1.2):(5.5-6.5), the amount ratio of boron trifluoride ether to 7-hydroxy-4-methoxyisophenone is 1g:50-60μL; the alkalinization time is 1-1.5h; the heating and reaction temperature is 75-80°C, and the time is 8-10h.

7. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 1, characterized by, The mass ratio of modified β-cyclodextrin and modified starch in step S1 is 3: (7-10), and the total mass of modified β-cyclodextrin and modified starch is 10%-15% of the mass of the wall material solution; the emulsifier is prepared by mixing monoglyceride and sucrose ester according to a mass ratio of 2: (8-10); in step S3, the rotating speed of the homogenizer is 15000-20000 rpm, and the time is 3-5 min; in step S4, the inlet air temperature of the spray drying is 150-170℃, the outlet air temperature is 70-80℃, and the feeding amount is 5-8 mL / min.

8. The method of preparing the microcapsule formulation containing oregano essential oil according to claim 1, characterized by, The added amount of the wall material solution is 50%-100% of the weight of the core material; the added amount of the emulsifier is 10%-20% of the weight of the core material; and the added amount of the stabilizer is 2.5%-5% of the weight of the core material.

9. A microcapsule formulation containing oregano essential oil, characterized in that, Prepared by the preparation method of any one of claims 1-8.

10. Use of the microcapsule preparation containing oregano essential oil according to claim 9 in the preparation of a feed additive.

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