Litsea lanceolata essential oil composition with bacteriostatic effect as well as preparation method and application of litsea lanceolata essential oil composition

Abstract

The invention discloses a fructus cinnamoii essential oil composition with a bacteriostatic effect as well as a preparation method and application thereof, and relates to the technical field of medicines. The invention discloses a fructus cinnamoii essential oil composition with a bacteriostatic effect, and the fructus cinnamoii essential oil composition with the bacteriostatic effect comprises the following components: 1-3.5 parts by mass of fructus cinnamoii essential oil, 1 part by mass of a wall material composed of gelatin and Arabic gum in a mass ratio of 0.4: 0.6-0.7: 0.3, and 0-4 parts by volume of a formaldehyde solution, the preparation method of the composition is simple, and the composition has a remarkable inhibiting effect on aspergillus flavus, penicillium expansum and fusarium oxysporum, and has a good application prospect. The invention can be used for preparing fungus inhibitors. The fructus cinnamoii essential oil microcapsule prepared from the fructus cinnamoii composition provided by the invention is stable in physicochemical property and remarkable in antibacterial effect, the preparation method is simple, and the fructus cinnamoii essential oil microcapsule has a wide market application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of medicines, and in particular to a Litsea cubeba essential oil composition with antibacterial effect, and a preparation method and application thereof. Background Art

[0002] Mildew is one of the main causes of quality and safety problems in Chinese medicinal materials, agricultural products, etc. It not only increases the safety risk of food and medicine use, but also causes huge waste of resources and economic losses. Taking active anti-mildew measures during storage is an important means to ensure the quality and safety of Chinese medicinal materials, agricultural products, etc., and exploring and developing green, broad-spectrum, and economical antibacterial and anti-mildew agents to control mildew is still one of the important ways to ensure food and drug safety. Plant essential oils can achieve good anti-mildew maintenance effects when used alone or in combination, and are highly safe. They have good prospects in the development of antibacterial and anti-mildew products instead of chemical synthetic agents.

[0003] Litsea cubeba essential oil is derived from the dried fruit of the plant Migao of the Lauraceae family, and is included in the "Guizhou Traditional Chinese Medicine and Ethnic Medicinal Materials Standards" (2019 edition). Studies have found that Litsea cubeba essential oil is a new green anti-mold resource with great development potential. The essential oil has a broad-spectrum antibacterial and fungal effect, and the minimum bactericidal concentration for Aspergillus flavus, Aspergillus niger, Trichoderma harzianum, Chaetomium globosum, Mucor racemosus, and Rhizopus niger is 10-20 μL·mL -1 , the efficacy is related to ingredients such as spartol, α-pinene, 4-terpineol, D-limonene, and octahydrotetramethylnaphthalene methanol; the essential oil is applied to the mildew prevention of Chinese medicinal materials that are prone to mildew, such as coix seed. When the concentration reaches 0.05% (V / V) or above, it can effectively prevent the mildew of the protected object, and the mildew inhibition rate reaches more than 90%. However, like other natural plant essential oils, the essential oil of Litsea cubeba has the disadvantages of strong volatility, poor thermal stability, and strong odor, which leads to reduced antibacterial activity and certain restrictions on its promotion and use. Finding a suitable method to improve the stability of essential oils, control the release rate, and shield the odor of excessively high concentrations has become an urgent problem to be solved in the development and application of this plant essential oil. Microencapsulation technology is a microcapsule technology that uses natural or synthetic polymer materials to encapsulate solid or liquid substances to form a semi-permeable or sealed capsule membrane. This technology can encapsulate the core material to be protected into tiny particles with a diameter of micrometers or nanometers, so as to achieve the function of fixing, protecting and controlling the release of the core material. The application of this technology to encapsulate plant essential oils can not only increase stability, reduce volatility, and extend shelf life, but also improve antibacterial properties and mask their special odor. Currently, this technology has been widely used in many fields such as food, medicine, and pesticides.

[0004] In the prior art, there is no relevant research on the microencapsulation of Litsea cubeba essential oil. Based on this, the present invention provides a Litsea cubeba essential oil composition with antibacterial effect, combines microencapsulation technology to prepare a Litsea cubeba essential oil microcapsule, and determines the optimal process conditions of the microcapsule through process parameter investigation, aiming to improve the stability of Litsea cubeba essential oil, reduce the preparation cost, and provide theoretical support for expanding its market application. Summary of the invention

[0005] The invention aims to provide a Litsea cubeba essential oil composition with antibacterial effect.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned Litsea cubeba essential oil composition.

[0007] Another object of the present invention is to provide a use of the above-mentioned Litsea cubeba essential oil composition in the preparation of fungal inhibitors.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] The Litsea cubeba essential oil composition with antibacterial effect comprises the following components: 1 to 3.5 parts by weight of Litsea cubeba essential oil, 1 part by weight of a wall material composed of gelatin and gum arabic in a mass ratio of 0.4:0.6 to 0.7:0.3, and 0 to 4 parts by volume of formaldehyde solution.

[0010] Preferably, the Litsea cubeba essential oil composition with antibacterial effect of the present invention comprises the following components: 2.5 to 3.5 parts by mass of Litsea cubeba essential oil, 1 part by mass of a wall material composed of gelatin and gum arabic in a mass ratio of 0.45:0.55 to 0.55:0.45, and 2 to 4 parts by volume of formaldehyde solution.

[0011] Further preferably, the Litsea cubeba essential oil composition with antibacterial effect of the present invention comprises the following components: 3.5 parts by mass of Litsea cubeba essential oil, 1 part by mass of a wall material composed of gelatin and gum arabic in a mass ratio of 0.55:0.45, and 3 parts by volume of formaldehyde solution.

[0012] Preferably, the formaldehyde solution of the present invention is a formaldehyde aqueous solution with a volume concentration of 25%.

[0013] The preparation method of the Litsea cubeba essential oil composition with antibacterial effect of the present invention comprises the following steps:

[0014] S1: Gum arabic and gelatin were weighed according to the composition formula, 100 parts by volume of pure water were added, the mixture was placed in a 50°C constant temperature water bath, and a magnetic stirrer was used at a stirring speed of 200-600 rpm to stir until the mixture was completely dissolved;

[0015] S2: adding Litsea cubeba essential oil, and homogenizing for 3 min with a high-speed homogenizer at a homogenizing speed of 8000-20000 rpm to obtain an emulsion;

[0016] S3: Adjust the pH value to 3.8-4.6 with 10% acetic acid, continue stirring in a 50°C constant temperature water bath for 30 minutes, transfer to room temperature and stir until the temperature drops below 30°C, then transfer to an ice water bath and continue stirring until the temperature drops below 10°C;

[0017] S4: adding 25% formaldehyde solution in the formula, adjusting the pH to 8-9 with 1 mol / L NaOH solution, and continuing to stir in an ice water bath for 0.5-3 h to allow cross-linking and curing to be complete, thereby obtaining microcapsules;

[0018] S5: separating and washing the microcapsules obtained in the above steps, removing water and freeze-drying them.

[0019] Preferably, in the method for preparing the Litsea cubeba essential oil composition with antibacterial effect of the present invention:

[0020] The stirring speed in step S1 is 300-600 rpm;

[0021] The homogenization speed in step S2 is 16000-20000 rpm;

[0022] The pH value in step S3 is adjusted to 4.0-4.4;

[0023] The stirring time in the ice water bath in step S4 is 2 to 3 hours.

[0024] Further preferably, in the method for preparing the Litsea cubeba essential oil composition with antibacterial effect of the present invention:

[0025] The stirring speed in step S1 is 500 rpm;

[0026] The homogenization speed in step S2 is 20000 rpm;

[0027] The pH value in step S3 is adjusted to 4.2;

[0028] The stirring time in the ice-water bath in step S4 is continued for 2.5 h.

[0029] Application of the Litsea cubeba essential oil composition of the present invention in the preparation of fungal inhibitors.

[0030] Preferably, the fungi of the present invention include any one or more of Aspergillus flavus, Penicillium expansum and Fusarium oxysporum.

[0031] Preferably, the dosage form of the fungal inhibitor of the present invention includes any one of powder, microcapsule, granule, tablet, aqueous emulsion, emulsion and paste.

[0032] The unit of mass parts in the present invention is g, and the unit of volume parts is mL.

[0033] Beneficial effects of the present invention:

[0034] 1. The present invention provides a composition containing Litsea cubeba essential oil, which is composed of Litsea cubeba essential oil, gelatin, gum arabic and formaldehyde solution. The composition has a simple formula and can be used to prepare Litsea cubeba essential oil microcapsules. The Litsea cubeba essential oil microcapsules prepared from the above composition have stable physicochemical properties, significant antibacterial effects, simple preparation methods, and broad market application prospects.

[0035] 2. The inventor investigated the factors that affect the encapsulation effect of Litsea cubeba essential oil microcapsules and found that the optimal process parameters for Litsea cubeba essential oil microcapsules are: homogenization speed of 20000rpm, curing agent (25% formaldehyde) addition of 3mL, stirring speed of 500rpm, curing time of 2.5h, pH value of 4.2, core-wall ratio of 3.5:1 (g:g), wall material ratio of 0.55:0.45 (g:g). The embedding rate of Litsea cubeba essential oil microcapsules prepared under the above optimal process parameters can reach an average of 94.59%, and the highest can reach 95.92%.

[0036] 3. The Litsea cubeba essential oil microcapsules prepared under the optimal process parameters provided by the present invention have the following advantages: (1) the particle size distribution of the microcapsules is uniform; (2) the capsule wall of the microcapsule is rigid and has a good protective effect on the core material; (3) the capsule wall is stable and does not chemically react with the core material, which is beneficial to ensure the integrity of the core material components; (4) the thermal stability of the Litsea cubeba essential oil encapsulated by gelatin-arabic gum is improved at high temperatures; (5) the microcapsules have a significant inhibitory effect on Aspergillus flavus, Penicillium expansum and Fusarium lanceolatum. Under the experimental conditions of this study, when the amount of microcapsules used is 350 mg, the growth of the above fungi can be completely inhibited. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the standard curve of Litsea cubeba essential oil;

[0038] Figure 2 The effects of different homogenization speeds on essential oil emulsification and microcapsule formation;

[0039] Figure 3 The particle size diagram of microcapsules prepared under different homogenization speed conditions;

[0040] Figure 4The morphology of microcapsules prepared under different stirring speed conditions;

[0041] Figure 5 The effect of different stirring speeds on the embedding efficiency and particle size of Litsea cubeba essential oil microcapsules;

[0042] Figure 6 The morphology of microcapsules prepared under different core-to-wall ratios;

[0043] Figure 7 The effects of different core-to-wall ratios on the encapsulation efficiency and particle size of Litsea cubeba essential oil microcapsules;

[0044] Figure 8 The morphology of microcapsules prepared under different wall material ratios;

[0045] Fig. 9 To study the effects of different wall material ratios on the embedding efficiency and particle size of Litsea cubeba essential oil microcapsules;

[0046] Fig.10 The morphology of microcapsules prepared under different pH conditions;

[0047] Fig.11 The effect of different pH values ​​on the embedding efficiency and particle size of Litsea cubeba essential oil microcapsules;

[0048] Fig.12 The morphology of microcapsules prepared under different curing time conditions;

[0049] Fig.13 The effect of different curing time on the embedding efficiency and particle size of Litsea cubeba essential oil microcapsules;

[0050] Fig.14 The effect of different curing time on the drying and forming of microcapsules;

[0051] Fig.15 The effect of different curing agent addition amounts on the drying and forming of microcapsules;

[0052] Fig.16 It is the corresponding surface diagram of the interaction between each factor;

[0053] Fig.17 is the particle size distribution diagram of microcapsules;

[0054] Fig.18 Microscopic and SEM observation pictures of microcapsules containing Litsea cubeba essential oil and blank microcapsules;

[0055] Fig.19 is the Fourier infrared spectrum;

[0056] Fig. 20 is the thermogravimetric analysis diagram;

[0057] Fig.21 This is a graph showing the antibacterial effect of microcapsules on Aspergillus flavus, Penicillium expansum and Fusarium oxysporum. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is described in detail below in conjunction with specific embodiments. The following embodiments are only used for explanation and illustration, and do not constitute a limitation on the technical solution of the present invention.

[0059] Example 1

[0060] The composition of Litsea cubeba essential oil with antibacterial effect has the following formula:

[0061] 3.5g Litsea cubeba essential oil, 0.55g gelatin, 0.45g gum arabic, 3mL 25% formaldehyde solution.

[0062] Example 2

[0063] The composition of Litsea cubeba essential oil has the following formula:

[0064] 1.5g Litsea cubeba essential oil, 0.45g gelatin, 0.55g gum arabic, 1mL 25% formaldehyde solution.

[0065] Example 3

[0066] The composition of Litsea cubeba essential oil with antibacterial effect has the following formula:

[0067] 3.5g Litsea cubeba essential oil, 0.6g gelatin, 0.4g gum arabic, 4mL 25% formaldehyde solution.

[0068] Example 4

[0069] Preparation method of Litsea cubeba essential oil composition with antibacterial effect:

[0070] S1: Gum arabic and gelatin were weighed according to the composition formula, 100 mL of pure water was added, and the mixture was placed in a 50°C constant temperature water bath, and stirred with a magnetic stirrer at a stirring speed of 500 rpm until the mixture was completely dissolved;

[0071] S2: adding Litsea cubeba essential oil, and homogenizing with a high-speed homogenizer at a homogenizing speed of 20,000 rpm for 3 minutes to obtain an emulsion;

[0072] S3: Adjust the pH value to 4.2 with 10% acetic acid, continue stirring in a 50°C constant temperature water bath for 30 minutes, transfer to room temperature and stir until the temperature drops below 30°C, then transfer to an ice water bath and continue stirring until the temperature drops below 10°C;

[0073] S4: adding 25% formaldehyde solution in the formula, adjusting the pH to 8.5 with 1 mol / L NaOH solution, and continuing to stir in an ice water bath for 2.5 h to allow cross-linking and curing to be complete, thereby obtaining microcapsules;

[0074] S5: separating and washing the microcapsules obtained in the above steps, removing water and freeze-drying them.

[0075] Example 5

[0076] Preparation method of Litsea cubeba essential oil composition with antibacterial effect:

[0077] S1: Gum arabic and gelatin were weighed according to the composition formula, 100 mL of pure water was added, and the mixture was placed in a 50°C constant temperature water bath, and stirred with a magnetic stirrer at a stirring speed of 200 rpm until the mixture was completely dissolved;

[0078] S2: adding Litsea cubeba essential oil, and homogenizing with a high-speed homogenizer at a homogenizing speed of 20,000 rpm for 3 minutes to obtain an emulsion;

[0079] S3: Adjust the pH value to 3.8 with 10% acetic acid, continue stirring in a 50°C constant temperature water bath for 30 minutes, transfer to room temperature and stir until the temperature drops below 30°C, then transfer to an ice water bath and continue stirring until the temperature drops below 10°C;

[0080] S4: adding 25% formaldehyde solution in the formula, adjusting the pH to 8.0 with 1 mol / L NaOH solution, and continuing to stir in an ice water bath for 3 h to allow cross-linking and curing to be complete, thereby obtaining microcapsules;

[0081] S5: separating and washing the microcapsules obtained in the above steps, removing water and freeze-drying them.

[0082] Example 6

[0083] Preparation method of Litsea cubeba essential oil composition with antibacterial effect:

[0084] S1: Gum arabic and gelatin were weighed according to the composition formula, 100 mL of pure water was added, and the mixture was placed in a 50°C constant temperature water bath, and stirred with a magnetic stirrer at a stirring speed of 600 rpm until the mixture was completely dissolved;

[0085] S2: adding Litsea cubeba essential oil, and homogenizing with a high-speed homogenizer at a homogenizing speed of 8000 rpm for 3 min to obtain an emulsion;

[0086] S3: Adjust the pH value to 4.4 with 10% acetic acid, continue stirring in a 50°C constant temperature water bath for 30 minutes, transfer to room temperature and stir until the temperature drops below 30°C, then transfer to an ice water bath and continue stirring until the temperature drops below 10°C;

[0087] S4: adding 25% formaldehyde solution in the formula, adjusting the pH to 9.0 with 1 mol / L NaOH solution, and continuing to stir in an ice water bath for 0.5 h to allow cross-linking and curing to be complete, thereby obtaining microcapsules;

[0088] S5: separating and washing the microcapsules obtained in the above steps, removing water and freeze-drying them.

[0089] Example 7

[0090] The Litsea cubeba essential oil composition is used for preparing fungal inhibitors of Aspergillus flavus, Penicillium expansum and Fusarium oxysporum.

[0091] In order to further verify the reliability of the present invention and screen out the best solution, the inventor conducted a series of experiments, as follows:

[0092] 1. Study on the preparation of Litsea cubeba essential oil microcapsules

[0093] 1. Reagents, materials and instruments

[0094] 1.1 Main reagents and materials

[0095] Gelatin (Shanghai Sangon Bioengineering Co., Ltd., batch number: C411BA0005), gum arabic (Chengdu Kelong Chemical Reagent Factory, batch number: 20220208), formaldehyde (Chengdu Busan Chemical Reagent Co., Ltd., batch number: 20230322), anhydrous ethanol (Tianjin Xinbote Chemical Co., Ltd., batch number: 20240108), anhydrous magnesium sulfate (Xilong Scientific Co., Ltd., batch number: 1911192).

[0096] Litsea cubeba: collected from Ceheng County, Guizhou Province, and identified by Xiao Chenghong, a senior laboratory technician from Guizhou University of Traditional Chinese Medicine, as the dried mature fruit of Cinnamomum migao HWLi, a plant of the Lauraceae family.

[0097] Litsea cubeba essential oil: extracted in the laboratory. The extraction method is to crush the Litsea cubeba medicinal material and pass it through a 50-mesh sieve, weigh about 200g, extract the volatile oil according to the 2020 edition of the "Chinese Pharmacopoeia" Part IV (General Chapter 2204 B Method), and dry it with anhydrous magnesium sulfate to obtain the essential oil.

[0098] 1.2 Main instruments

[0099] UV-visible spectrophotometer (Shimadzu Instrument Co., Ltd., UV-2700), optical microscope (Olympus Co., Ltd., Japan, SZX7), electronic analytical balance (Mettler-Toledo, ME204), constant temperature magnetic stirrer (Shanghai Lichen Instrument Technology Co., Ltd., LC-MSA-LD), and intelligent artificial climate chamber (Tianjin Test Instrument Co., Ltd., GZX-400EF).

[0100] 2. Methods

[0101] 2.1 Preparation of Litsea cubeba essential oil microcapsules

[0102] Weigh 0.5g of gum arabic powder and gelatin respectively and place them in a beaker, add 100mL of pure water, and stir while heating in a 50℃ water bath until completely dissolved. Add 1g of Litsea cubeba essential oil and homogenize it in a high-speed homogenizer at a speed of 12000rpm for 3min to obtain an emulsion. Adjust the pH to below 4.5 with 10% acetic acid solution, continue stirring for 30min in a 50℃ constant temperature heating magnetic stirrer, transfer to room temperature and stir until the temperature drops below 30℃, then move to an ice water bath and continue stirring until the temperature drops below 10℃, add an appropriate amount of 25% formaldehyde solution, and adjust the pH to 8-9 with 1mol / L NaOH solution, and continue stirring in an ice water bath for a certain period of time to completely crosslink and solidify. Separate and wash the obtained microcapsules, remove water as much as possible, and freeze-dry to obtain Litsea cubeba essential oil microcapsule particles.

[0103] 2.2 Drawing of the standard curve of Litsea cubeba essential oil

[0104] A certain concentration of Litsea cubeba essential oil-anhydrous ethanol solution was prepared, and anhydrous ethanol was used as a control. An ultraviolet spectrophotometer was used to scan in the range of 200-400nm, and its characteristic peak was selected to measure the maximum absorption wavelength.

[0105] Prepare a series of concentration gradients of Litsea cubeba essential oil-anhydrous ethanol solutions. Accurately weigh 0.5g of Litsea cubeba essential oil, place it in a 50mL volumetric flask and dilute it with anhydrous ethanol, accurately draw 0.08, 0.12, 0.16, 0.20, 0.24, 0.28mL of the above solution, place it in a 10mL volumetric flask, and dilute it with anhydrous ethanol to obtain a solution to be tested with a concentration of 0.08, 0.12, 0.16, 0.20, 0.24, 0.28mg / mL of Litsea cubeba essential oil. Determine the absorbance of the solution to be tested at the above-mentioned maximum absorption wavelength measured, and draw a standard curve of Litsea cubeba essential oil with the absorbance value as the ordinate and the concentration of the Litsea cubeba essential oil solution as the abscissa.

[0106] 2.3 Determination of embedding efficiency

[0107] The filtrate and washing liquid of the microcapsule were collected, mixed and transferred to a 250 mL volumetric flask, fixed to volume with dilute ethanol, and the absorbance was measured. The content of Litsea cubeba essential oil in the mixed solution of the filtrate and washing liquid was calculated according to the standard curve, which was the essential oil content outside the microcapsule. The embedding rate of the microcapsule was calculated according to the following formula:

[0108]

[0109] 2.4 Study on the preparation technology of Litsea cubeba essential oil

[0110] 2.4.1 Single-factor experimental design

[0111] Taking the embedding rate and particle size as indicators, the effects of homogenization speed, stirring speed, core-to-wall ratio, wall material ratio, pH value, curing time and curing agent addition amount on the embedding rate, particle size and structure of Litsea cubeba essential oil microcapsules were studied when other conditions remained unchanged, so as to obtain the optimal process parameters for the preparation of Litsea cubeba essential oil microcapsules.

[0112] (1) Homogenization speed: The effects of homogenization speeds of 8000 rpm, 12000 rpm, 16000 rpm, and 20000 rpm on the emulsification effect of essential oils and the particle size and structure of microcapsules were investigated.

[0113] (2) Stirring speed: This experiment used constant speed magnetic stirring to ensure that the product could be fully contacted and evenly dispersed. The effects of stirring speeds of 200 rpm, 300 rpm, 400 rpm, 500 rpm, and 600 rpm on the encapsulation efficiency, particle size, and structure of the formed microcapsules were investigated.

[0114] (3) Core-to-wall ratio: The effects of the core-to-wall ratio (Litsea cubeba essential oil / total of wall materials gelatin and gum arabic) of 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and 3.5:1 on the encapsulation efficiency, particle size, and structure of the formed microcapsules were investigated.

[0115] (4) Wall material ratio: The effects of the wall material ratio (gelatin / gum arabic) of 0.4:0.6, 0.45:0.55, 0.5:0.5, 0.55:0.45, 0.6:0.4, and 0.7:0.3 on the encapsulation efficiency, particle size, and structure of the formed microcapsules were investigated.

[0116] (5) pH value: The effects of pH values ​​of 4.6, 4.4, 4.2, 4.0, and 3.8 on the encapsulation efficiency, particle size, and structure of the formed microcapsules were investigated during the coagulation process.

[0117] (6) Curing time: The effects of curing time of 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, and 3 h on the encapsulation efficiency, particle size, and structure of the formed microcapsules were investigated.

[0118] (7) Amount of curing agent added: The effects of adding 0 mL, 1 mL, 2 mL, 3 mL, and 4 mL of curing agent (25% formaldehyde) on the drying of the finished essential oil microcapsules were investigated.

[0119] 2.4.2 Response surface experimental design

[0120] Based on the results of the single factor test, the response surface test determined that the homogenization speed was 20000rpm, the stirring speed was 500rpm, the curing time was 2.5h, and the amount of curing agent added was 3mL. With pH value (A), core-to-wall ratio (B), and wall material ratio (C) as independent variables, the appropriate single factor range was selected, and the embedding rate was used as the response value. The response surface experimental design was performed using Design-Expert13.0 software. A three-factor three-level response surface experiment was designed, and the results were fitted by quadratic regression and variance analysis to obtain the optimal parameters of each variable. A verification experiment was performed based on the optimal model parameters. Three parallels were performed for each group of treatments to verify the reliability of the model and analyze the final optimization results. The experimental design is shown in Table 1.

[0121] Table 1. Response surface optimization test factors and levels for the preparation process of Litsea cubeba essential oil microcapsules

[0122]

[0123] 3. Results and analysis

[0124] 3.1 Drawing of the standard curve of Litsea cubeba essential oil

[0125] A 0.2 mg / mL Litsea cubeba essential oil-anhydrous ethanol solution was prepared, and anhydrous ethanol was used as a control. The solution was scanned in the range of 200 to 400 nm using an ultraviolet spectrophotometer, and the maximum absorption wavelength of the characteristic peak was measured to be 273 nm.

[0126] The absorbance of Litsea cubeba essential oil-anhydrous ethanol test solution with different concentrations was measured at a wavelength of 273nm, and the standard curve of Litsea cubeba essential oil was drawn with the absorbance value as the ordinate and the concentration of Litsea cubeba essential oil as the abscissa. The results showed that the linear relationship of Litsea cubeba essential oil was good in the concentration range of 0.08-0.28mg / mL, and the linear regression equation was: y=1.9122x-0.0003, R 2 =0.9994. The standard curve of Litsea cubeba essential oil is shown in Figure 1 .

[0127] 3.2 Single factor experimental results and analysis

[0128] 3.2.1 Effect of homogenization speed on essential oil emulsification and microcapsule preparation

[0129] The degree of emulsification of essential oils is the key to whether they can form capsules. The better the emulsification, the more conducive it is to capsule formation. It can be seen from the experimental results that capsules can be formed when the homogenization speed is 8000rpm~20000rpm. The higher the homogenization speed, the smaller the droplets of essential oil emulsification, and the smaller the particle size of the prepared microcapsules. It can be seen from the molding shape and particle size of the microcapsules that when the homogenization speed is 20000rpm, the microcapsule particle size is the smallest, and the core material distribution is more uniform and delicate. Therefore, 20000rpm is selected as the optimal homogenization speed. Results are shown in Figure 2 , Figure 3 .

[0130] 3.2.2 Effect of stirring speed on microcapsule formation and embedding effect

[0131] On the one hand, the appropriate mechanical stirring speed is conducive to the wall material fully gathering around the oil droplets to form capsules when the material is encapsulated, and on the other hand, it can prevent the formed microcapsules from sticking and agglomerating into blocks when the microcapsules are solidified. The effects of different stirring speeds on the morphology, size and embedding rate of Litsea cubeba essential oil microcapsules are shown in Figure 4 , Figure 5 .

[0132] From the results, it can be seen that within the speed range of 200-600rpm, the effect of stirring speed on the particle size of microcapsules has a significant difference (p < 0.5), but there is no significant difference on the embedding rate (p > 0.5). In low-speed stirring, the difference in oil content in microcapsules of different particle sizes is very significant. Microcapsules with larger particle sizes obviously embed more essential oil than microcapsules with smaller particle sizes. This may be because when stirring at low speed, the essential oil is unevenly distributed in the entire system. When the generated coagulants can be fully deposited on the surface of the emulsion droplets, the microcapsules formed have a larger particle size and more essential oil is embedded. On the contrary, the particle size of the microcapsules formed is relatively small. When the rotation speed is 200rpm, the microcapsule particle size is the largest, with an average particle size of 109.28μm. When the rotation speed is 500rpm, the microcapsule particle size is the smallest, with an average particle size of 68.66μm, and the embedding rate is also the largest, reaching 82.70%. At the same time, the microcapsules are relatively regular spheres, and the essential oil in the capsules is relatively dispersed. From Figure 5 It can be seen that the average particle size of microcapsules increases as the speed decreases, and the average particle size of microcapsules decreases as the speed increases. The particle size of microcapsules first decreases and then increases with the increase of speed, and the embedding rate first increases and then decreases. Therefore, a comprehensive analysis of the morphology of microcapsules, embedding effect, etc. determined that 500rpm is the optimal stirring speed.

[0133] 3.2.3 Effect of core-to-wall ratio on microcapsule formation and encapsulation effect

[0134] Results Figure 6 , Figure 7 .Depend on Figure 6It can be seen that when the core-to-wall ratio is 1:1, the prepared microcapsules are relatively empty and uneven in size. This may be due to the small amount of essential oil, which is not enough to distribute around the capsule material. In addition, the small amount of encapsulated essential oil will lead to waste of capsule material and shrinkage of capsules during drying. When the core-to-wall ratio is 1.5:1-3.5:1, the obtained microcapsules are full and uniform, but as the amount of essential oil encapsulated increases, the particle size of the microcapsules will increase. When the amount of essential oil added exceeds 3.5g, the content of essential oil floating on the upper surface after the reaction increases. Some microcapsules are not round, the capsule shape is oval, and the capsule wall is too thin, resulting in microcapsule rupture, etc., which reduces the utilization rate of the core material and causes waste of core material. Figure 7 It can be seen that as the core-to-wall ratio increases, the embedding rate of the microcapsules increases first and then decreases. When the core-to-wall ratio is 3:1, the microcapsule embedding rate reaches the maximum, with an average value of 91.06%. When the core-to-wall ratio increases to 3.5:1, the microcapsule embedding rate decreases to an average value of 78.67%. Through experimental observation, the core-to-wall ratio has a great influence on the microcapsule molding and embedding rate. Therefore, the core-to-wall ratio is selected as the response surface investigation condition, and the factor step size is set to 2.5:1~3.5:1.

[0135] 3.2.4 Effect of wall material ratio on microcapsule molding and embedding effect

[0136] Results Figure 8 , Fig. 9 The wall material is one of the main components of microcapsules, and a suitable proportion of the capsule material is conducive to the formation of the capsule wall. Fig. 9 It can be seen that the wall material ratio has a great influence on the formation of microcapsules. When the wall material ratio (gelatin: gum arabic) is in the range of 0.45:0.55 to 0.6:0.4, the microcapsule formation effect is better. When the wall material ratio is 0.4:0.6 and 0.7:0.3, the capsule material cannot well encapsulate the essential oil to obtain a round capsule ball. Fig. 9 It can be seen that when the wall material ratio is 0.5:0.5, the embedding rate of the prepared Litsea cubeba essential oil microcapsules is the highest among the six groups of experiments, the particle size of the microcapsules is the smallest, and the capsule spherical forming effect is better. Since the capsule material has a great influence on the formation and embedding of microcapsules, the wall material ratio is selected as the response surface investigation condition, and the factor step size is set to 0.45:0.55~0.55:0.45.

[0137] 3.2.5 Effect of pH value on microcapsule formation and embedding effect

[0138] Results Fig.10 , Fig.11The pH value is a key factor affecting the aggregation of microcapsules. 10% acetic acid is used to adjust the pH value of the emulsified Litsea cubeba essential oil-gelatin-gum arabic mixture to below the isopotential of gelatin (pH 4.5) to make it positively charged, while gum arabic is negatively charged. Due to the mutual attraction of charges, positive and negative ion complexes are formed, and the solubility is reduced, resulting in aggregation. Fig.10 It can be seen that when the pH value is adjusted to 4.6, the ideal microcapsule morphology cannot be obtained, and the obtained coacervate is observed to be irregular long coacervate under a microscope. The reason may be that under acidic conditions, the solubility of the emulsion is reduced and coacervate is formed. However, due to the insufficient acid value, the positively charged amino groups (-NH 3 + ) and negatively charged carboxyl groups (-COO － ) is less, which directly affects the degree of ionization and fails to obtain ideal microcapsules. Fig.11 Analysis shows that the pH value has a great influence on the particle size and embedding rate of microcapsules. When the pH value varies in the range of 3.8 to 4.4, the larger the pH value, the better the encapsulation ability of the capsule material for essential oils, the greater the embedding rate, and the smaller the particle size of the obtained microcapsules. When the pH value is 4.4, the embedding rate is the largest and the particle size is the smallest in the experimental group of the single-factor experimental design. Therefore, when other conditions are fixed, the pH value of 4.4 is the optimal pH value condition for preparing Litsea cubeba essential oil microcapsules in the experimental group. Since pH value is an important factor in the preparation of microcapsules, the interaction between pH value and wall material has a great influence on the formation of microcapsules. Therefore, pH value is selected as the response surface investigation condition, and the factor step size is set to pH4.2 to pH4.6.

[0139] 3.2.6 Effect of curing time on microcapsule forming and embedding effect

[0140] The temperature of the microcapsule solution that has condensed into capsules is lowered to below 10°C, and the pH value is adjusted to 8-9 with 1 mol / L NaOH solution. After adding a curing agent, curing begins. During curing, the aldehyde group in the formaldehyde can react with the amino group in the gelatin molecule to produce a Schiff base reaction, causing cross-linking between gelatins to form a three-dimensional network structure, which stabilizes the capsule wall of the microcapsule. After curing, the microcapsules are washed, and the surface moisture is removed and then freeze-dried.

[0141] Results Fig.12 , Fig.13 .Depend on Fig.12 and Fig.13It can be seen that the curing time has a certain influence on the embedding rate and particle size of the microcapsules. When the curing time is greater than 1.5h, there is no significant difference in the effect on the embedding rate of the microcapsules (P>0.5). The longer the curing time, the smaller the particle size of the prepared Litsea cubeba essential oil microcapsules. There is no significant difference in the particle size of the microcapsules prepared with a curing time of 1.5h and 3.0h (P>0.5). Fig.14 It can be seen that the curing time has a great influence on the drying and molding of microcapsules. When the curing time is less than 1.5h, the ideal microcapsule product cannot be obtained by drying, which means that the cross-linking and curing cannot be completed in a short time, and the capsule wall is unstable and sticks together during drying. When the curing time is 2.0h, dry particles can be obtained, but the particle dispersion is poor, and a small part of them is adhered. When the curing time is greater than 2.5h, the microcapsule product obtained is a microcapsule product obtained by drying particles with good dispersion.

[0142] In summary, the curing time affects the particle size, embedding rate and drying molding of microcapsules, but when the curing time is greater than 2.5h, the influence is not significant. In order to save time in preparing microcapsules, the optimal curing time condition for microcapsules is selected as 2.5h.

[0143] 3.2.7 Effect of curing agent addition on microcapsule drying and molding

[0144] A hardening agent, also called a cross-linking agent, is a type of chemical substance that can generate chemical bonds between linear molecules, linking the linear molecules together and acting as a bridge, thereby achieving a three-dimensional network structure formed by bonding and cross-linking multiple linear molecules. In the complex coacervation method, chemical hardeners such as glutaraldehyde, formaldehyde, tannic acid, glycerol, and jingpingning, and enzyme hardeners such as TG enzymes are usually used. The hardener used in this experiment is a 25% formaldehyde solution. Insufficient use of the hardener will affect the failure of the microcapsule wall to be completely cross-linked and cured during curing and will not play a stabilizing role. Excessive use and excessive formaldehyde residues will also be harmful to the environment. Therefore, the experimental design fixed other factors, and when the amount of water added was 100 mL, the effects of adding 0, 1, 2, 3, and 4 mL of the hardener on the drying of the microcapsules to obtain the finished product were investigated. The results are shown in Fig.15 The results show that when no curing agent is added or a small amount of curing agent is added, the capsule wall will adhere and completely dispersed particles cannot be obtained. When the amount of curing agent added is greater than 3 mL, a microcapsule product with good dispersion and no adhesion can be obtained. In order to reduce formaldehyde residues, the amount of curing agent added is selected to be 3 mL.

[0145] 3.3 Response surface experiment results and analysis

[0146] On the basis of the single factor experiment, the response surface experimental design was carried out with pH value (A), core-to-wall ratio (B), and wall material ratio (C) as independent variables and embedding rate as dependent variable. The response surface experimental design and results are shown in Table 2. The data in Table 2 were subjected to regression analysis using Design-Expert 13.0 software. After regression fitting of each factor, the regression equation was obtained:

[0147] Y=92.32-4.56*A-2.27*B+2.73*C-3.25*AB+0.3825*AC+2.65*BC-3.42*A 2 -

[0148] 1.47*B 2 -2.34*C 2

[0149] The results of variance analysis of the response surface model are shown in Table 3. The model's F = 42.66, P < 0.0001, indicating that the regression model is significant. The lack of fit term F = 4.83, P = 0.0812> 0.05, indicating that the difference is not statistically significant, not significant, unknown factors have little interference with the experiment, and the model fit is good, which can be used for prediction and analysis.

[0150] The coefficient of determination R of the model 2 =0.9821, indicating that the model can explain 98.21% of the response value changes, indicating that the model has a good fit with the actual experiment and the experimental error is small. 2 adj =0.9591, coefficient of variation (CV) =1.19%, indicating that the model has good predictive power and there is no big difference between the actual value and the predicted value. 2 , C 2 The P values ​​of AB and BC were all less than 0.01, and the influence on embedding rate was extremely significant. 2 P=0.0247, P<0.05, significant effect, P=0.4918, P>0.05, no significant effect. The factors affecting the microcapsule embedding rate of Litsea cubeba essential oil in the first term are ranked in order of size: A(pH)>C(wall material ratio)>B(core wall ratio).

[0151] According to the regression equation, the interaction between pH value (A), core-to-wall ratio (B), and wall material ratio (C) was analyzed. The response surface diagram of the interaction relationship of each factor is shown in Fig.16 The contour lines in the figure are all elliptical, and the variation range is obvious, indicating that the interaction between the factors is obvious, but the ellipse presented by the AC contour line is closer to a circle, and the interaction is smaller than that of AB and BC, which corresponds to the model results.

[0152] In addition, the model was analyzed using Design-Expert.13 software, and the target value of the embedding rate was set to the maximum value. The optimal process conditions and predicted results were obtained through software optimization, that is, the optimal preparation conditions of Litsea cubeba essential oil microcapsules were pH 4.2, core-wall ratio (mass ratio of Litsea cubeba essential oil to total mass ratio of wall material gelatin + gum arabic) of 3.5:1 (g:g), and wall material ratio (mass ratio of gelatin and gum arabic) of 0.55:0.45 (g:g). Under this condition, the embedding rate of Litsea cubeba essential oil microcapsules predicted by the model was 95.62%. Under this condition, three repeated experiments were carried out for verification experiments, and the actual embedding rates were 94.59%, 95.92%, and 94.72%, respectively, with an average of 95.08%. The RSD value of the predicted and actual embedding rates was 0.40%, indicating that the preparation process of Litsea cubeba essential oil microcapsules optimized by the response surface method was reasonable and feasible.

[0153] Table 2 Results of response surface optimization test on preparation process of Litsea cubeba essential oil microcapsules

[0154]

[0155]

[0156] Table 3 Analysis of variance table of response surface model

[0157]

[0158] Note: “**” indicates extremely significant difference (P<0.01); “*” indicates significant difference (P<0.05).

[0159] 4. Discussion and summary

[0160] In this chapter, gelatin and gum arabic were used as composite wall materials to prepare Litsea cubeba essential oil microcapsules by complex coacervation method. The effects of seven single factors, namely pH value, core-to-wall ratio, wall material ratio, stirring speed, homogenization speed, curing agent addition amount and curing time, on the preparation of Litsea cubeba essential oil microcapsules by complex coacervation method were investigated. Then, three factors, namely pH value, core-to-wall ratio and wall material ratio, which had a greater impact on the preparation of microcapsules, were selected for response surface experiments. Finally, the optimal process for preparing Litsea cubeba essential oil microcapsules was obtained as follows: homogenization speed of 20000rpm, curing agent addition amount of 3mL, stirring speed of 500rpm, curing time of 2.5h, pH of 4.2, core-to-wall ratio of 3.5:1 (g:g), and wall material ratio of 0.55:0.45 (g:g). The maximum embedding rate of Litsea cubeba essential oil microcapsules prepared under these optimal conditions can reach 95.92%.

[0161] 2. Study on the performance characterization of Litsea cubeba essential oil microcapsules

[0162] 1. Materials, reagents and instruments

[0163] 1.1 Main materials and reagents

[0164] Aspergillus flavus (BNCC336678), Penicillium expansum (BNCC146144), and Fusarium oxysporum (BNCC340967) were all purchased from Beina Chuanglian Biotechnology Co., Ltd.; the rest of the materials and reagents were the same as in “1. Research on the preparation of microcapsules of essential oil from Litsea cubeba”.

[0165] 1.2 Main instruments

[0166] Laser micron particle size analyzer (MasterSizer2000, Malvern, UK), scanning electron microscope (QuattroS, Thermo Fisher), energy spectrum (EDAX ELECT PIUS), Fourier transform infrared spectrometer (Thermo Fisher, IN10), thermogravimetric analyzer (NETZSCH, TG209F1).

[0167] 2. Methods

[0168] 2.1 Particle size and particle size distribution determination

[0169] Use a laser micron particle size analyzer to measure, add an appropriate amount of double distilled water to the measuring cell, start the standard operating procedure, calibrate the optical path, and adjust the laser intensity. When the computer displays that the sample has been added, slowly add a small amount of microcapsule powder to the measuring cell until the shading degree reaches the required level, then start measuring. The computer will automatically display the particle size distribution.

[0170] 2.2 Appearance and structure observation

[0171] The appearance structure of the microcapsules was observed by optical microscope and scanning electron microscope (SEM). The specific operation of SEM observation is as follows: stick a layer of conductive glue on the sample stage, sprinkle the microcapsule powder evenly on the conductive glue, blow away the excess microcapsule powder next to it, and observe the surface morphology of the sample in high vacuum mode after gold spraying. The electron gun acceleration voltage is 3kV.

[0172] 2.3 Fourier infrared spectrum analysis

[0173] Fourier transform infrared spectrometer was used to analyze the sample in the wavelength range of 600-4000cm -1 Scanning was performed under 400 °C to analyze its chemical composition. In order to verify the embedding of Litsea cubeba essential oil microcapsules, a certain amount of Litsea cubeba essential oil microcapsules, Litsea cubeba essential oil, wall materials and empty capsules were taken. 5 mg of the above samples were accurately weighed, 200 mg of dried KBr powder was added, and ground into uniform fine powder in an agate mortar. A small amount was taken in a tablet press and pressed into a transparent film, and then infrared spectrum detection was performed.

[0174] 2.4 Thermogravimetric analysis

[0175] The thermal stability of Litsea cubeba essential oil, microcapsules and empty capsules was determined by thermogravimetric analysis. 2 The temperature was raised from 40°C to 700°C at a rate of 10°C in an air flow and its mass loss was observed.

[0176] 2.5 Study on antibacterial properties of microcapsules

[0177] In order to understand the effect of microencapsulation process on the antibacterial properties of essential oils, in vitro antibacterial tests were conducted on microcapsules by fumigation. First, fresh bacterial blocks of the same size were placed in the center of sterile and solidified PDA culture medium, and then essential oil microcapsules of different masses (0, 100, 150, 200, 250, 300, 350 mg) were placed in sterilized non-woven bags to prepare microcapsule antibacterial active packaging, which was placed in the center of the culture dish lid, and the culture dish was sealed with a sealing film. The antibacterial zone diameter was measured in a 27°C constant temperature incubator for 5 days, and the amount of microcapsules that completely inhibited the growth of mold was taken as the minimum antibacterial amount. The space and addition amount of the culture dish should be considered in the calculation. The experiment was repeated three times, and the blank control group was taken without adding essential oil microcapsules. The plate without colony growth was cultured for 5 days, and the minimum amount of microcapsules without colony growth was taken as the minimum bactericidal amount.

[0178] 3. Results and analysis

[0179] 3.1 Particle size and particle size distribution determination

[0180] The results are as follows Fig.17 As shown, the size distribution of the prepared Litsea cubeba essential oil microcapsules is 91.20-363.07 μm, and the microcapsules smaller than 250 μm account for 97.67%. The particle size of the capsules is normally distributed, indicating that the particle size of the microcapsules prepared under the optimal process conditions is relatively uniform.

[0181] 3.2 Appearance and structure observation

[0182] Results Fig.18 .Depend on Fig.18It can be seen that the macrocarpon essential oil microcapsules and blank microcapsules are round and full before drying. It can be clearly seen that the oil-containing microcapsule wall is wrapped with essential oil. Since there is no essential oil in the blank microcapsule, it presents a small blank ball in the wall. After freeze drying, SEM observation shows that the microcapsule wall is a three-dimensional mesh structure. After freeze drying, the blank microcapsules agglomerated into sheets, which may be due to the volatilization of water inside the freeze drying process, and the shrinkage of the wall material caused depressions to form sheets. Although the water in the blank microcapsule cavity evaporates under low-temperature vacuum freezing, the wall composed of gelatin and gum arabic only shrinks instead of completely breaking, and the structure remains intact, which shows that the microcapsules have strong rigidity. After freeze drying, the macrocarpon essential oil microcapsules are still round as a whole, with typical wrinkles and three-dimensional mesh structure on the surface, and no voids or fragmentation. At the same time, compared with the wet capsules before freeze drying, the particle size is significantly reduced. The structure of the capsule wall remains intact, indicating that it has a good protective effect on the core material.

[0183] 3.3 Fourier transform infrared spectrum analysis

[0184] Results Fig.19 The results show that the infrared spectra of the blank microcapsules of gelatin and gum arabic retain the characteristic absorption peaks of gelatin and gum arabic respectively. However, due to the complex coacervation reaction between the two polymers of gelatin and gum arabic to generate new coacervates, the infrared spectra of the blank microcapsules have obvious changes in the carboxyl-amino region, with a peak at 1640 cm -1 There is a sharp peak at the - The group makes the -NH 3 + The absorption peak disappeared, and no special peak that did not exist in Macrocarpon essential oil and blank microcapsules was found in the infrared spectrum of Macrocarpon essential oil microcapsules, which indicated that no new chemical bonds were generated. This further confirmed that the complex coacervation method only resulted in electrostatic interaction between the wall materials, and the core material would not undergo other chemical reactions with the microcapsule wall material, which was beneficial to ensure the integrity of the core material components.

[0185] 3.4 Thermogravimetric analysis

[0186] The results are as follows Fig. 20As shown in the figure, as the temperature rises, the core material Litsea cubeba essential oil begins to decompose rapidly at 50°C, and the decomposition rate of the essential oil is extremely fast. The decomposition rate reaches the maximum at 148.4°C, which is 15.37% / min. It is basically completely decomposed before the temperature reaches 210°C, and the mass loss reaches 98.03%. Compared with the ordinary uncoated Litsea cubeba essential oil, due to the protection of gelatin-arabic gum coagulants, the decomposition rate of Litsea cubeba essential oil microcapsules is greatly reduced, and its thermal stability is effectively improved. This shows that the wall material has a protective effect on the core material and achieves the purpose of embedding.

[0187] 3.5 Study on antibacterial properties

[0188] The results are as follows Fig.21 As shown. The results show that there is no significant difference in the inhibition zone between the blank microcapsules and the blank control group (P>0.5), and the blank microcapsules have no antibacterial effect on Aspergillus flavus, Penicillium expansum and Fusarium oxysporum. Compared with the blank microcapsules and the blank control group, the microcapsules containing Litsea cubeba essential oil have obvious antibacterial effects on the tested bacteria. The minimum inhibitory dose of Litsea cubeba essential oil microcapsules for Aspergillus flavus is 150mg, and the minimum bactericidal dose is 300mg; the minimum inhibitory dose for Penicillium expansum is 150mg, and the minimum bactericidal dose is 300mg; the minimum inhibitory dose for Fusarium oxysporum is 300mg, and the minimum bactericidal dose is 350mg. When the usage is 350mg, the growth of Aspergillus flavus, Penicillium expansum and Fusarium oxysporum can be completely inhibited.

[0189] 4. Conclusion and summary

[0190] This chapter mainly uses optical microscopy, scanning electron microscopy, infrared, thermogravimetry and other methods to characterize the physicochemical properties of Litsea cubeba essential oil microcapsules prepared under the optimal process, such as morphological structure, molecular structure, interaction force, thermal stability and antibacterial performance. The conclusions are as follows:

[0191] (1) The appearance structure observation results show that the prepared Litsea cubeba essential oil microcapsules have a regular spherical multi-core structure, are evenly dispersed, and have a size distribution of 91.20 to 363.07 μm, which can effectively provide protection for the core material.

[0192] (2) Fourier transform infrared spectrum analysis confirmed that the composite coacervate was formed by physical interaction between GE and GA, and there was no other chemical bond interaction between the wall material and the core material except the electrostatic force between the composite wall materials.

[0193] (3) The results of thermogravimetric analysis showed that the thermal stability of Litsea cubeba essential oil at high temperature was enhanced after complex coacervation encapsulation.

[0194] (4) Antibacterial performance studies have shown that the microcapsules of Litsea cubeba essential oil have a significant antibacterial effect on Aspergillus flavus, Penicillium expansum and Fusarium oxysporum. When the usage is 350 mg, it can completely inhibit the growth of Aspergillus flavus, Penicillium expansum and Fusarium oxysporum.

[0195] Although the present invention has been described in detail above by means of general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A Litsea cubeba essential oil composition with antibacterial effect, characterized in that: The invention comprises the following components: 1 to 3.5 parts by weight of Litsea cubeba essential oil, 1 part by weight of a wall material composed of gelatin and gum arabic in a mass ratio of 0.4:0.6 to 0.7:0.3, and 0 to 4 parts by volume of formaldehyde solution.

2. The composition of Litsea cubeba essential oil with antibacterial effect according to claim 1, characterized in that it comprises the following components: 2.5 to 3.5 parts by mass of Litsea cubeba essential oil, 1 part by mass of a wall material composed of gelatin and gum arabic in a mass ratio of 0.45:0.55 to 0.55:0.45, and 2 to 4 parts by volume of formaldehyde solution.

3. The Litsea cubeba essential oil composition with antibacterial effect according to claim 2, characterized in that: The invention comprises the following components: 3.5 parts by weight of Litsea cubeba essential oil, 1 part by weight of a wall material consisting of gelatin and gum arabic in a mass ratio of 0.55:0.45, and 3 parts by volume of formaldehyde solution.

4. The Litsea cubeba essential oil composition with antibacterial effect according to any one of claims 1 to 3, wherein: The formaldehyde solution is a formaldehyde aqueous solution with a volume concentration of 25%.

5. The method for preparing the Litsea cubeba essential oil composition with antibacterial effect as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1: Gum arabic and gelatin were weighed according to the composition formula, 100 parts by volume of pure water were added, the mixture was placed in a 50°C constant temperature water bath, and a magnetic stirrer was used at a stirring speed of 200-600 rpm to stir until the mixture was completely dissolved; S2: adding Litsea cubeba essential oil, and homogenizing for 3 min with a high-speed homogenizer at a homogenizing speed of 8000-20000 rpm to obtain an emulsion; S3: Adjust the pH value to 3.8-4.6 with 10% acetic acid, continue stirring in a 50°C constant temperature water bath for 30 minutes, transfer to room temperature and stir until the temperature drops below 30°C, then transfer to an ice water bath and continue stirring until the temperature drops below 10°C; S4: adding 25% formaldehyde solution in the formula, adjusting the pH to 8-9 with 1 mol / L NaOH solution, and continuing to stir in an ice water bath for 0.5-3 h to allow cross-linking and curing to be complete, thereby obtaining microcapsules; S5: separating and washing the microcapsules obtained in the above steps, removing water and freeze-drying them.

6. The method for preparing the Litsea cubeba essential oil composition with antibacterial effect according to claim 5, characterized in that: The stirring speed in step S1 is 300-600 rpm; The homogenization speed in step S2 is 16000-20000 rpm; The pH value in step S3 is adjusted to 4.0-4.4; The stirring time in the ice water bath in step S4 is 2 to 3 hours.

7. The method for preparing the Litsea cubeba essential oil composition with antibacterial effect according to claim 6, characterized in that: The stirring speed in step S1 is 500 rpm; The homogenization speed in step S2 is 20000 rpm; The pH value in step S3 is adjusted to 4.2; The stirring time in the ice-water bath in step S4 is continued for 2.5 h.

8. Use of the Litsea cubeba essential oil composition with antibacterial effect as claimed in any one of claims 1 to 3 in the preparation of fungal inhibitors.

9. The use according to claim 8, characterized in that: The fungus is any one or more of Aspergillus flavus, Penicillium expansum and Fusarium oxysporum.

10. The use according to claim 8, characterized in that: The dosage form of the fungus inhibitor includes any one of powder, microcapsule, granule, tablet, aqueous emulsion, emulsion and paste.

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