Galangal essential oil microcapsule as well as preparation method and application thereof

Abstract

The invention relates to the technical field of microcapsule preparation and application, and discloses a galangal essential oil microcapsule and a preparation method and application thereof, and the preparation method at least comprises the following steps: S1, raw material preparation; s2, performing pretreatment; s3, emulsifying; s4, carrying out microencapsulation; and S5, collecting and screening. The alpinia galangal essential oil is embedded through a microencapsulation technology to form solid microcapsules, interference of external environmental factors can be effectively isolated, the chemical stability and physical stability of the alpinia galangal essential oil are remarkably improved, volatilization loss is reduced to the maximum extent, and then the shelf life of the alpinia galangal essential oil is prolonged; after microencapsulation, the dispersibility and solubility of the alpinia galangal essential oil in water are remarkably improved, the alpinia galangal essential oil can be conveniently applied to a water-based system, the application range is greatly expanded, meanwhile, the microcapsules can achieve slow release of the alpinia galangal essential oil, the essential oil is gradually released in a specific time and environment, the action time of the essential oil is effectively prolonged, and the utilization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microcapsule preparation and application, and in particular to a galangal essential oil microcapsule and a preparation method and application thereof. Background Art

[0002] As a natural extract, Alpinia officinalis essential oil possesses a variety of biological activities, including antibacterial, antioxidant, anti-inflammatory, and mosquito repellent properties. It demonstrates enormous potential for application in a wide range of fields, including food, medicine, agriculture, and daily chemicals. However, Alpinia officinalis essential oil itself suffers from volatilization, chemical instability, and low bioavailability, significantly limiting its practical application. Microencapsulation technology, as an effective means of protection and controlled release, can encapsulate Alpinia officinalis essential oil within a wall material, effectively addressing these issues. However, existing Alpinia officinalis essential oil microcapsules still have room for improvement in terms of wall material selection, preparation process, and application expansion, requiring further optimization and innovation. Summary of the Invention

[0003] In view of this, the embodiments of the present invention hope to provide an Alpinia officinalis essential oil microcapsule and a preparation method and application thereof, so as to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial choice.

[0004] The technical solution of the embodiment of the present invention is achieved as follows: a galangal essential oil microcapsule and a preparation method and application thereof, comprising the following steps:

[0005] S1. Raw material preparation: prepare Alpinia officinalis essential oil, wall material, emulsifier, curing agent, and synergistic factor;

[0006] S2. Pretreatment: placing the wall material in a container in water according to a certain proportion, and forming a wall material solution with a porous network structure by dynamic pH response complex coacervation method;

[0007] S3, emulsification: perform emulsification operations according to specific methods;

[0008] S4. Microencapsulation: microencapsulation is performed according to a specific method;

[0009] S5. Collection and sieving: Collect the spray-dried microcapsule products and perform sieving.

[0010] The object of the present invention can also be achieved by the following technical measures, wherein the raw material composition percentages in the step S1, raw material preparation, are as follows:

[0011] a. The total mass fraction of the greater galangal essential oil in the entire microcapsule system is not less than 72.25%, and the greater galangal essential oil is extracted by low-temperature fractional distillation technology and contains ≥85% of terpenoids and phenolic active ingredients;

[0012] b. The wall material is formed by complex coagulation of chitosan, polylysine and sodium caseinate, wherein the degree of deacetylation of chitosan is 96.0% -99.0%, wherein the mass ratio of chitosan, polylysine, sodium caseinate is 3:2:1;

[0013] c. The amount of the emulsifier is 1%-5% of the total mass of the wall material solution. The role of the emulsifier is to form a stable oil-in-water emulsion by reducing the interfacial tension, while minimizing the possible adverse effects on the subsequent performance of the microcapsules, thereby ensuring the quality and stability of the microcapsules;

[0014] d. The curing agent is used in an amount of 1.5%-2% of the total mass of the wall material. By cross-linking the chitosan amino groups, the mechanical shear strength of the capsule wall is increased by more than 40%, preventing the microcapsules from agglomerating and rupturing during storage, thereby extending their shelf life.

[0015] e. The amount of the synergistic factor is 3% to 5% by mass, and the essential oil nanoparticles are protected from agglomeration through hydrogen bonding during the freeze-drying stage.

[0016] The object of the present invention can also be achieved by the following technical measures, wherein the steps of extracting the essential oil of Alpinia officinarum are as follows:

[0017] a. Select fresh, pest-free Alpinia officinalis plants, wash and dry them, and cut them into pieces or segments of appropriate size;

[0018] b. Place the processed raw material of Alpinia officinarum into the distillation kettle of the distillation equipment, paying attention to the loading amount;

[0019] c. Add water to the distillation kettle in a ratio of 1:1-1:2;

[0020] d. After connecting the distillation equipment, start the first distillation, distill at 80 ° C, negative pressure 0.08 MPa conditions for 30 minutes to extract low-boiling point terpenes, and then start the second distillation again, raise the temperature to 105 ° C, and distill at atmospheric pressure for 60 minutes to collect high-boiling point phenolic compounds to form an oil-water mixture. The distillation is carried out in stages to avoid high temperature damage to the active ingredients.

[0021] e. The oil-water mixture was collected into a separator to separate the crude galangal essential oil from the upper layer;

[0022] f. Dry the crude essential oil with a desiccant such as anhydrous sodium sulfate, and then filter it through filter paper or a filter to obtain Alpinia officinalis essential oil with a purity of ≥98%.

[0023] The purpose of the present invention can also be achieved by the following technical measures. The specific method in the emulsification step S3 is as follows:

[0024] S3-1. Place the emulsifier and Alpinia officinalis essential oil in a reaction vessel and stir at 30°C to 40°C at a speed of 300-500 r / min for 10-15 minutes;

[0025] S3-2. Slowly add the mixed solution in step S3-1 to the wall material solution preheated to 40°C-50°C, and add the compounded stabilizer at the same time;

[0026] S3-3: Emulsify the mixture by high-speed shearing (800-1200 r / min) and ultrasonic wave (200-300 W) for 40-60 minutes to form a stable oil-in-water emulsion.

[0027] The purpose of the present invention can also be achieved by the following technical measures. The specific method in the S4, microencapsulation step is as follows:

[0028] S4-1. Add acetic acid solution dropwise to the oil-in-water emulsion prepared in S3 to adjust the pH value of the system to 4.5-5.0, and stir at a low speed (e.g., 100-200 rpm) in a constant temperature water bath at 40-60°C for 0.5-2.0 hours to form a microcapsule suspension;

[0029] S4-2, slowly add curing agent to the microcapsule suspension, stir and react in a constant temperature water bath at 50-60°C for 2-3 hours, so that the cross-linking degree of the capsule wall reaches more than 92%;

[0030] S4-3. Glucose is added as a protective agent, and the mixture is spray-dried at an inlet air temperature of 110° C. and an atomization pressure of 0.6 MPa to obtain microcapsules with a moisture content of less than 3%.

[0031] The object of the present invention can also be achieved by the following technical measures: in the step S5, collecting and screening, the spray-dried microcapsule product is collected and screened to remove impurities and incompletely formed microcapsule particles.

[0032] The purpose of the present invention can also be achieved by the following technical measures. The dynamic pH response complex coacervation method is to dissolve chitosan, polylysine and sodium caseinate in deionized water in a mass ratio of 3:2:1, and heat it to 50±1°C and stir it at a constant temperature of 100-200r / min, add 1mol / L acetic acid solution at a rate of 5mL / min, and start 800r / min high-speed shear stirring to reduce the pH value from 7.0 to 4.8. During this period, the chitosan amino group is protonated to form an electrostatic complex with the carboxyl group of sodium caseinate and wrap the oil droplets. After the pH reaches 4.8, a 5% w / v calcium chloride solution accounting for 0.5% of the total mass of the wall material is immediately added. 2+The bridging of sodium caseinate carboxyl groups increases the crosslinking degree of the capsule wall to more than 92%, and the average pore size is reduced from 500-800nm ​​to 200-500nm. Finally, the stirring speed is reduced to 100-200r / min and the reaction is continued for 30-60 minutes to form a three-dimensional interpenetrating porous network structure with a capsule wall thickness of 5-10μm.

[0033] The object of the present invention can also be achieved by the following technical measures, wherein the curing agent in step S4 is genipin or tannic acid, and the amount of the curing agent is 35%-60% of the total mass of chitosan and polylysine.

[0034] The object of the present invention can also be achieved by the following technical measures: the spray drying adopts an airflow spray drying method, the air inlet temperature is 100-120°C, the air outlet temperature is 60-80°C, and the atomization pressure is 0.4-0.88MPa.

[0035] The objectives of the present invention can also be achieved through the following technical measures, wherein in the food industry, the microcapsules are added to liquid milk at a mass ratio of 0.3%, and the pH-responsive sustained-release properties are used to achieve targeted release of antibacterial ingredients, thereby extending the shelf life of liquid milk from 7 days to 21 days, and the vitamin C retention rate is increased by 18% compared with the control group; in the medical field, it can be used to prepare drugs with antioxidant, analgesic or anti-inflammatory effects, etc.

[0036] The embodiment of the present invention adopts the above technical solution, which has the following advantages:

[0037] 1. The present invention uses microencapsulation technology to embed Alpinia officinarum essential oil to form solid microcapsules, which can effectively isolate the interference of external environmental factors, significantly improve the chemical and physical stability of Alpinia officinarum essential oil, minimize volatilization loss, and thus extend its shelf life. In addition, Alpinia officinarum essential oil is generally insoluble in water. After microencapsulation, its dispersibility and solubility in water are significantly improved, making it easy to apply to aqueous systems, greatly expanding its scope of application. At the same time, the microcapsules can achieve the slow release of Alpinia officinarum essential oil, allowing the essential oil to be gradually released at a specific time and environment, effectively extending its action time and improving its utilization efficiency.

[0038] 2. During the preparation process of the present invention, various conditions, such as temperature, stirring speed, amount and speed of adding reagents, etc., are carefully set to ensure that the preparation process is scientific and reasonable, has strong operability, and can stably prepare high-quality greater galangal essential oil microcapsule products. The addition of the curing agent is mainly used to enhance the stability of the microcapsules during storage, effectively prevent the microcapsules from agglomerating, rupturing and other problems during storage, extend the shelf life, and facilitate the storage and transportation of the product.

[0039] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the following detailed description. DETAILED DESCRIPTION

[0040] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the description is considered to be illustrative and non-restrictive in nature.

[0041] It should be noted that the terms "first," "second," "symmetrical," "array," etc. are used only to distinguish descriptions from positional descriptions and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, limitations on features such as "first" and "symmetrical" may explicitly or implicitly include one or more of these features; similarly, when the number of certain features is not limited in the form of words such as "two" or "three," it should be noted that these features also explicitly or implicitly include one or more of the number of features.

[0042] In the present invention, unless otherwise expressly specified or limited, terms such as "installation," "connection," and "fixation" should be understood broadly; for example, they may refer to fixed connection, detachable connection, or integral molding; they may refer to mechanical connection, direct connection, welding, or indirect connection via an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specification and specific circumstances.

[0043] Some technical problems, main solutions, minor technical problems and solutions

[0044] The embodiments of the present invention are described in detail below.

[0045] The embodiment of the present invention provides a galangal essential oil microcapsule and a preparation method and application thereof, and the galangal essential oil microcapsule and a preparation method and application thereof include the following steps:

[0046] S1. Raw material preparation: prepare Alpinia officinalis essential oil, wall material, emulsifier, curing agent, and synergistic factor;

[0047] S2. Pretreatment: placing the wall material in a container in water according to a certain proportion, and forming a wall material solution with a porous network structure by dynamic pH response complex coacervation method;

[0048] S3, emulsification: perform emulsification operations according to specific methods;

[0049] S4. Microencapsulation: microencapsulation is performed according to a specific method;

[0050] S5. Collection and sieving: Collect the spray-dried microcapsule products and perform sieving.

[0051] Specifically, the percentages of raw materials in step S1, raw material preparation, are as follows:

[0052] a. The total mass fraction of Alpinia officinalis essential oil in the entire microcapsule system is not less than 72.25%. The Alpinia officinalis essential oil is extracted by low-temperature fractional distillation technology and contains ≥85% of terpenoids and phenolic active ingredients;

[0053] b. The wall material is formed by complex coagulation of chitosan, polylysine and sodium caseinate, wherein the degree of deacetylation of chitosan is 96.0%-99.0%, and the mass ratio of chitosan, polylysine and sodium caseinate is 3:2:1;

[0054] c. The amount of emulsifier is 1%-5% of the total mass of the wall material solution. The role of the emulsifier is to form a stable oil-in-water emulsion by reducing the interfacial tension, while minimizing the possible adverse effects on the subsequent performance of the microcapsules, thereby ensuring the quality and stability of the microcapsules;

[0055] d. The curing agent is used in an amount of 1.5%-2% of the total mass of the wall material. By cross-linking the amino groups of chitosan, the mechanical shear strength of the capsule wall is increased by more than 40%, preventing the microcapsules from agglomerating and rupturing during storage, thereby extending their shelf life.

[0056] e. The amount of the synergistic factor is 3% to 5% by mass, and the essential oil nanoparticles are protected from agglomeration through hydrogen bonding during the freeze-drying stage.

[0057] Specifically, the steps for extracting the essential oil of Alpinia officinalis are as follows:

[0058] a. Select fresh, pest-free Alpinia officinalis plants, wash and dry them, and cut them into pieces or segments of appropriate size;

[0059] b. Place the processed raw material of Alpinia officinarum into the distillation kettle of the distillation equipment, paying attention to the loading amount;

[0060] c. Add water to the distillation kettle in a ratio of 1:1-1:2;

[0061] d. After connecting the distillation equipment, start the first distillation, distill at 80 ° C, negative pressure 0.08 MPa conditions for 30 minutes to extract low-boiling point terpenes, and then start the second distillation again, raise the temperature to 105 ° C, and distill at atmospheric pressure for 60 minutes to collect high-boiling point phenolic compounds to form an oil-water mixture. The distillation is carried out in stages to avoid high temperature damage to the active ingredients.

[0062] e. The oil-water mixture was collected into a separator to separate the crude galangal essential oil from the upper layer;

[0063] f. Dry the crude essential oil with a desiccant such as anhydrous sodium sulfate, and then filter it through filter paper or a filter to obtain Alpinia officinalis essential oil with a purity of ≥98%.

[0064] Specifically, the specific method in S3, the emulsification step is as follows:

[0065] S3-1. Place the emulsifier and Alpinia officinalis essential oil in a reaction vessel and stir at 30°C to 40°C at a speed of 300-500 r / min for 10-15 minutes;

[0066] S3-2. Slowly add the mixed solution in step S3-1 to the wall material solution preheated to 40°C-50°C, and add the compounded stabilizer at the same time;

[0067] S3-3: Emulsify the mixture by high-speed shearing (800-1200 r / min) and ultrasonic wave (200-300 W) for 40-60 minutes to form a stable oil-in-water emulsion.

[0068] Specifically, the specific method in S4, microencapsulation step is as follows:

[0069] S4-1. Add acetic acid solution dropwise to the oil-in-water emulsion prepared in S3 to adjust the pH value of the system to 4.5-5.0, and stir at a low speed (e.g., 100-200 rpm) in a constant temperature water bath at 40-60°C for 0.5-2.0 hours to form a microcapsule suspension;

[0070] S4-2, slowly add curing agent to the microcapsule suspension, stir and react in a constant temperature water bath at 50-60°C for 2-3 hours, so that the cross-linking degree of the capsule wall reaches more than 92%;

[0071] S4-3. Glucose is added as a protective agent, and the mixture is spray-dried at an inlet air temperature of 110° C. and an atomization pressure of 0.6 MPa to obtain microcapsules with a moisture content of less than 3%.

[0072] Specifically, in step S5, collecting and screening, the spray-dried microcapsule product is collected and screened to remove impurities and incompletely formed microcapsule particles.

[0073] Specifically, the dynamic pH response complex coacervation method is to dissolve chitosan, polylysine, and sodium caseinate in deionized water at a mass ratio of 3:2:1, and heat it to 50±1°C and stir it at a constant temperature of 100-200r / min, add 1mol / L acetic acid solution at a rate of 5mL / min, and start 800r / min high-speed shear stirring to reduce the pH value from 7.0 to 4.8. During this period, the chitosan amino group is protonated to form an electrostatic complex with the carboxyl group of sodium caseinate and wrap the oil droplets. After the pH reaches 4.8, a 5% w / v calcium chloride solution accounting for 0.5% of the total mass of the wall material is immediately added. 2+ Bridging the carboxyl groups of sodium caseinate increases the crosslinking degree of the capsule wall to more than 92% and reduces the average pore size from 500-800 nm to 200-500 nm. Finally, the stirring speed is reduced to 100-200 r / min and the reaction is continued for 30-60 minutes to form a three-dimensional interpenetrating porous network structure with a capsule wall thickness of 5-10 μm.

[0074] Specifically, the curing agent in step S4 is genipin or tannic acid, and the amount of the curing agent is 35%-60% of the total mass of chitosan and polylysine.

[0075] Specifically, the spray drying adopts an airflow spray drying method, with an air inlet temperature of 100-120°C, an air outlet temperature of 60-80°C, and an atomization pressure of 0.4-0.88MPa.

[0076] Specifically, in the food industry, the microcapsules are added to liquid milk at a mass ratio of 0.3%. Through their pH-responsive sustained-release properties, the targeted release of antibacterial ingredients is achieved, extending the shelf life of liquid milk from 7 days to 21 days, and the vitamin C retention rate is increased by 18% compared with the control group; in the medical field, it can be used to prepare drugs with antioxidant, analgesic or anti-inflammatory effects.

[0077] Specific steps: raw material preparation, including Alpinia galanga essential oil, wall material prepared by complex coagulation method of chitosan, polylysine and sodium caseinate, emulsifier, curing agent, synergistic factor, wherein Alpinia galanga essential oil is extracted by selecting fresh, disease- and insect-free Alpinia galanga plants, washing and drying them carefully, cutting them into pieces or small segments of appropriate size, and placing the processed raw materials into the distillation kettle of the distillation equipment, paying attention to controlling the charging amount to avoid affecting the distillation effect, and then adding water to the distillation kettle, and keeping the ratio of water to raw materials between 1:1-1:2. After connecting the distillation equipment, start the first section of distillation, distill at 80°C and negative pressure of 0.08MPa for 30 minutes to extract low-boiling point terpene components, and start the second section of distillation again, raise the temperature to 105°C, and distill at normal pressure for 60 minutes to collect high-boiling point phenolic compounds to form an oil-water mixture, which is formed after cooling through a condenser, and the segmented distillation avoids high temperature destruction of the active ingredients, and collects the oil-water mixture into a separator. Due to the different densities of essential oil and water, The crude galangal essential oil in the upper layer is separated by a separatory funnel or other tools. Finally, the crude essential oil is dried with a desiccant such as anhydrous sodium sulfate, and then filtered through filter paper or a filter to obtain the galangal essential oil with a purity of ≥98%. The pretreatment is then carried out. The pretreatment is as follows: the wall material is placed in a container in proportion in water, and a wall material solution with a porous network structure is formed by a dynamic pH response complex coacervation method, wherein the dynamic pH response complex coacervation method is to mix chitosan, polylysine, and sodium caseinate according to mass. The chitosan was dissolved in deionized water at a ratio of 3:2:1, and the temperature was raised to 50±1℃ and stirred at a constant temperature of 100-200r / min. A 1mol / L acetic acid solution was added dropwise at a rate of 5mL / min. At the same time, a high-speed shear stirring of 800r / min was started to reduce the pH value from 7.0 to 4.8. During this period, the chitosan amino group was protonated to form an electrostatic complex with the carboxyl group of sodium caseinate and wrapped the oil droplets. After the pH reached 4.8, a 5% w / v calcium chloride solution accounting for 0.5% of the total mass of the wall material was immediately added. 2+The carboxyl groups of sodium caseinate are bridged to increase the crosslinking degree of the capsule wall to more than 92%, and the average pore size is reduced from 500-800nm ​​to 200-500nm. Finally, the stirring speed is reduced to 100-200r / min and the reaction is continued for 30-60 minutes to form a three-dimensional interpenetrating porous network structure with a capsule wall thickness of 5-10μm. Then, an emulsification operation is performed. The emulsifier and Alpinia officinalis essential oil are placed in a reaction container and stirred at a temperature of 30℃ to 40℃ for 300-500r / min. / min stirring for 10-15 minutes to fully disperse the emulsifier in the galangal essential oil, the amount of the emulsifier is 1%-5% of the total mass of the sodium caseinate aqueous solution, the galangal essential oil and the emulsifier, then the mixed solution in step S3-1 is slowly added to the pre-prepared and preheated to 40 ° C -50 ° C wall material solution, and the compound stabilizer is added at the same time, and the emulsifier is synergistically emulsified by high-speed shear (800-1200r / min) and ultrasonic (200-300W). The oil-in-water emulsion prepared by S3 is added dropwise with acetic acid solution to adjust the pH value of the system to 4.5-5.0, and the mixture is stirred at a low speed (e.g., 100-200 r / min) in a constant temperature water bath at 40-60°C for 0.5-2.0 hours to form a microcapsule suspension, and a curing agent is slowly added to the microcapsule suspension, and the mixture is kept at a constant temperature of 50-60°C. The reaction is stirred in a water bath for 2-3 hours to achieve a cross-linking degree of the capsule wall of more than 92%, wherein the curing agent is genipin or tannic acid, and the amount of the curing agent is 35%-60% of the total mass of chitosan and polylysine. Glucose is then added as a protective agent. The product is spray-dried at an inlet air temperature of 110°C and an atomization pressure of 0.6 MPa to obtain microcapsules with a moisture content of less than 3%. Finally, the spray-dried microcapsule product is collected and sieved to remove impurities and incompletely formed microcapsule particles.

[0078] The following are several specific embodiments of the present invention:

[0079] Example 1

[0080] Raw material preparation: Accurately weigh an appropriate amount of Alpinia officinalis essential oil to ensure that its mass fraction in the microcapsule system is not less than 72.25%. Weigh a certain amount of chitosan, polylysine, and sodium caseinate as wall materials, where the degree of deacetylation is 96.0%. Weigh sucrose fatty acid ester as an emulsifier at 1% of the total mass of the wall material solution. Weigh 1% of the total mass of the wall material solution as a curing agent.

[0081] Pretreatment: Add the wall material to an appropriate amount of water, heat to 50°C and stir until it is completely dissolved to form a uniform solution.

[0082] Emulsification: Place the emulsifier and Alpinia officinalis essential oil in a reaction vessel, stir at 300 r / min at 30°C for 15 minutes, slowly add the mixture into the wall material solution preheated to 40°C, and add the compound stabilizer at the same time. Then, use high-speed shearing at 800 r / min and ultrasonic wave at 200W to synergistically emulsify for 60 minutes to form a stable water-in-oil emulsion.

[0083] Microencapsulation: Acetic acid solution was added dropwise to the oil-in-water emulsion prepared by S3 to adjust the pH value to 4.5, and the mixture was stirred in a constant temperature water bath at 40°C for 1.0 hour to form a microcapsule suspension. The acetic acid solution was added at a rate of 1 ml / s and a stirring rate of 150 r / min. A curing agent was then slowly added to the microcapsule suspension. The curing agent was genipin, and the amount was 35% of the total mass of chitosan and polylysine. The mixture was stirred in a constant temperature water bath at 50°C for 3 hours. Finally, an air flow spray drying method was used, wherein the air inlet temperature was 100°C, the air outlet temperature was 60°C, and the atomization pressure was 0.4 MPa to obtain microcapsules.

[0084] Collection and screening: Collect the spray-dried microcapsule products and use screening equipment to remove impurities and incompletely formed microcapsule particles.

[0085] Example 2

[0086] Raw material preparation: select Alpinia officinalis essential oil to ensure its mass fraction, use chitosan with a deacetylation degree of 99.0%, adjust the wall material, emulsifier and curing agent, among which the amount of curing agent is 2% of the total mass of the wall material, and the amount of emulsifier is 5% of the total mass of the wall material solution.

[0087] Pretreatment: Dissolve the wall material in water, heat to 60°C and stir until it is completely dissolved to form a uniform solution.

[0088] Emulsification: Place the emulsifier and Alpinia officinalis essential oil in a reaction vessel, stir the emulsifier and essential oil at 40°C and 500 r / min for 10 minutes, add the wall material solution preheated to 50°C and add stabilizer to the mixture, set the high-speed shear to 1200 r / min and the ultrasonic to 300W for synergistic emulsification for 40 minutes to form a stable water-in-oil emulsion.

[0089] Microencapsulation: Acetic acid was added dropwise to the oil-in-water emulsion prepared from S3 to adjust the pH to 5.0, and the mixture was stirred in a water bath at 60°C for 0.5 hour with the acetic acid solution added at a rate of 10 ml / s and a stirring rate of 1000 r / min. A curing agent, tannic acid, was added in an amount of 60% of the total mass of chitosan and polylysine, and the mixture was stirred in a water bath at 60°C for 2 hours. The mixture was spray-dried to obtain microcapsules at an air inlet temperature of 120°C, an air outlet temperature of 80°C, and an atomization pressure of 0.88 MPa.

[0090] Collection and screening: Collect the spray-dried microcapsule products and use screening equipment to remove impurities and incompletely formed microcapsule particles.

[0091] Performance tests were performed on Example 1-Example 2:

[0092] Encapsulation efficiency determination: The encapsulation efficiency of the microcapsules was determined by high performance liquid chromatography. The encapsulation efficiency of the microcapsules prepared in Example 1 and Example 2 both reached a relatively high level.

[0093] Stability test: The microcapsules were placed under different environmental conditions, such as high temperature, high humidity, and light, and the morphology, active ingredient content and other indicators of the microcapsules were regularly tested. The results showed that the microcapsules were stable during storage.

[0094] Application effect verification

[0095] Food application: The microcapsules were added to liquid milk at a mass ratio of 0.3%. Through their pH-responsive sustained-release properties, they achieved targeted release of antibacterial ingredients, extending the shelf life of liquid milk from 7 days to 21 days. The vitamin C retention rate was also increased by 18% compared with the control group, verifying their feasibility as an additive in the food industry.

[0096] Medical applications: Through in vitro and animal experiments, the potential efficacy of microcapsules in the preparation of antioxidant, analgesic or anti-inflammatory drugs has been preliminarily verified.

[0097] It can be seen that the Alpinia officinalis essential oil microcapsules and the preparation method thereof of the present invention have good performance in terms of encapsulation efficiency, stability and application effect, as verified by the examples, and have practical application value. At the same time, the preparation method of the present invention can be adjusted and optimized according to different needs to adapt to applications in more fields.

[0098] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A galangal essential oil microcapsule and its preparation method and application, characterized in that: The following steps are involved: S1. Raw material preparation: prepare Alpinia officinalis essential oil, wall material, emulsifier, curing agent, and synergistic factor; S2. Pretreatment: placing the wall material in a container in water according to a certain proportion, and forming a wall material solution with a porous network structure by dynamic pH response complex coacervation method; S3, emulsification: perform emulsification operations according to specific methods; S4. Microencapsulation: microencapsulation is performed according to a specific method; S5. Collection and sieving: Collect the spray-dried microcapsule products and perform sieving.

2. The Alpinia officinalis essential oil microcapsule according to claim 1, and its preparation method and application, are characterized in that: The percentages of raw materials in the step S1, raw material preparation, are as follows: a. The total mass fraction of the greater galangal essential oil in the entire microcapsule system is not less than 72.25%, and the greater galangal essential oil is extracted by low-temperature fractional distillation technology and contains ≥85% of terpenoids and phenolic active ingredients; b. The wall material is formed by complex coagulation of chitosan, polylysine and sodium caseinate, wherein the degree of deacetylation of chitosan is 96.0% -99.0%, wherein the mass ratio of chitosan, polylysine, sodium caseinate is 3:2:1; c. The amount of the emulsifier is 1%-5% of the total mass of the wall material solution. The role of the emulsifier is to form a stable oil-in-water emulsion by reducing the interfacial tension, while minimizing the possible adverse effects on the subsequent performance of the microcapsules, thereby ensuring the quality and stability of the microcapsules; d. The curing agent is used in an amount of 1.5%-2% of the total mass of the wall material. By cross-linking the chitosan amino groups, the mechanical shear strength of the capsule wall is increased by more than 40%, preventing the microcapsules from agglomerating and rupturing during storage, thereby extending their shelf life. e. The amount of the synergistic factor is 3% to 5% by mass, and the essential oil nanoparticles are protected from agglomeration through hydrogen bonding during the freeze-drying stage.

3. The Alpinia officinalis essential oil microcapsule and its preparation method and application according to claim 2, characterized in that: The steps of extracting the Alpinia officinalis essential oil are as follows: a. Select fresh, pest-free Alpinia officinalis plants, wash and dry them, and cut them into pieces or segments of appropriate size; b. Place the processed raw material of Alpinia officinarum into the distillation kettle of the distillation equipment, paying attention to the loading amount; c. Add water to the distillation kettle in a ratio of 1:1-1:2; d. After connecting the distillation equipment, start the first distillation, distill at 80 ° C, negative pressure 0.08 MPa conditions for 30 minutes to extract low-boiling point terpenes, and then start the second distillation again, raise the temperature to 105 ° C, and distill at atmospheric pressure for 60 minutes to collect high-boiling point phenolic compounds to form an oil-water mixture. The distillation is carried out in stages to avoid high temperature damage to the active ingredients. e. The oil-water mixture was collected into a separator to separate the crude galangal essential oil from the upper layer; f. Dry the crude essential oil with a desiccant such as anhydrous sodium sulfate, and then filter it through filter paper or a filter to obtain Alpinia officinalis essential oil with a purity of ≥98%.

4. The Alpinia officinalis essential oil microcapsule according to claim 1, and its preparation method and application, are characterized in that: The specific method in the emulsification step S3 is as follows: S3-1. Place the emulsifier and Alpinia officinalis essential oil in a reaction vessel and stir at 30°C to 40°C at a speed of 300-500 r / min for 10-15 minutes; S3-2. Slowly add the mixed solution in step S3-1 to the wall material solution preheated to 40°C-50°C, and add the compounded stabilizer at the same time; S3-3: Emulsify the mixture by high-speed shearing (800-1200 r / min) and ultrasonic wave (200-300 W) for 40-60 minutes to form a stable oil-in-water emulsion.

5. The Alpinia officinalis essential oil microcapsule according to claim 1, and its preparation method and application, are characterized in that: The specific method in the S4, microencapsulation step is as follows: S4-1. Add acetic acid solution dropwise to the oil-in-water emulsion prepared in S3 to adjust the pH value of the system to 4.5-5.0, and stir at a low speed (e.g., 100-200 rpm) in a constant temperature water bath at 40-60°C for 0.5-2.0 hours to form a microcapsule suspension; S4-2, slowly add curing agent to the microcapsule suspension, stir and react in a constant temperature water bath at 50-60°C for 2-3 hours, so that the crosslinking degree of the capsule wall reaches more than 92%; S4-3. Glucose is added as a protective agent, and the mixture is spray-dried at an inlet air temperature of 110° C. and an atomization pressure of 0.6 MPa to obtain microcapsules with a moisture content of less than 3%.

6. The Alpinia officinalis essential oil microcapsule and its preparation method and application according to claim 1, characterized in that: In the step S5, collecting and screening, the spray-dried microcapsule product is collected and screened to remove impurities and incompletely formed microcapsule particles.

7. The Alpinia officinalis essential oil microcapsule and its preparation method and application according to claim 1, characterized in that: The dynamic pH response complex coacervation method is to dissolve chitosan, polylysine and sodium caseinate in deionized water in a mass ratio of 3:2:1, heat to 50±1°C and stir at a constant temperature of 100-200 r / min, add 1 mol / L acetic acid solution at a rate of 5 mL / min, and simultaneously start high-speed shear stirring at 800 r / min to reduce the pH value from 7.0 to 4.

8. During this period, the chitosan amino groups are protonated to form electrostatic complexes with the carboxyl groups of sodium caseinate and wrap the oil droplets. After the pH reaches 4.8, a 5% w / v calcium chloride solution accounting for 0.5% of the total mass of the wall material is immediately added. 2+ Bridging the carboxyl groups of sodium caseinate increases the crosslinking degree of the capsule wall to more than 92% and reduces the average pore size from 500-800 nm to 200-500 nm. Finally, the stirring speed is reduced to 100-200 r / min and the reaction is continued for 30-60 minutes to form a three-dimensional interpenetrating porous network structure with a capsule wall thickness of 5-10 μm.

8. The Alpinia officinalis essential oil microcapsule and its preparation method and application according to claim 5, characterized in that: The spray drying adopts an airflow spray drying method, with an air inlet temperature of 100-120° C., an air outlet temperature of 60-80° C., and an atomization pressure of 0.4-0.88 MPa.

9. The Alpinia officinalis essential oil microcapsule and its preparation method and application according to claim 1, characterized in that: In the food industry, the microcapsules are added to liquid milk at a mass ratio of 0.3%. Through their pH-responsive sustained-release properties, the targeted release of antibacterial ingredients is achieved, extending the shelf life of liquid milk from 7 days to 21 days, and the vitamin C retention rate is increased by 18% compared with the control group. In the medical field, they are used to prepare drugs with antioxidant, analgesic or anti-inflammatory effects.