Plant compound essential oil as well as preparation method and application thereof

Abstract

A preparation method of plant compound essential oil comprises the following steps: preparing mixed powder from dried lemon slices, mint and litsea coreana, carrying out carbon dioxide supercritical extraction, and collecting an extract; the preparation method comprises the following steps: dropwise adding a carboxymethyl-beta-cyclodextrin solution into a mixture of eugenol and thymol, carrying out ultrasonic treatment to obtain an ultrasonic mixed solution, standing, centrifuging, collecting supernate, and drying to obtain a white powdery inclusion compound; and adding lecithin, Tween 80, disodium pyrophosphate and deionized water into the extract, heating and stirring, continuing to add the inclusion compound, homogenizing to obtain a nano-emulsion, adding gelatin and propylene glycol, heating and preserving heat, and cooling to obtain the plant composite essential oil. The compound essential oil disclosed by the invention has antibacterial and antioxidant effects, and has relatively strong antibacterial ability on botrytis cinerea and penicillium germs, and the DPPH free radical scavenging rate is greater than or equal to 90%. According to the invention, the active ingredients of the essential oil are wrapped by carboxymethyl-beta-cyclodextrin and synergistically embedded by lipidosome through a nano-embedding technology to realize slow release, so that the antioxidant and antibacterial properties are effectively prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of plant essential oil preparation, and particularly relates to a plant compound essential oil, a preparation method thereof, and an application thereof. Background Art

[0002] Plant essential oils are a class of aromatic substances in the form of volatile oily liquids extracted from different tissue parts of higher plants such as flowers, leaves, roots, stems, and fruits, and are composed of phenols, terpenoids, aldehydes and ketones, alcohols, acids, and aromatic compounds. Among them, phenolic, terpene, and aldehyde and ketone compounds are the main antibacterial components, and alcohols, ethers, and hydrocarbon compounds also have a certain degree of bacteriostatic effect. Plant essential oils have functions such as antibacterial, antifungal, and antioxidant. As broad-spectrum bactericides, due to their characteristics such as high efficiency and long-lasting effect, they show extensive application value in multiple fields. For example, in the field of food and agricultural products, essential oils can be used as functional food additives to endow foods with antioxidant activity, improve food nutritional value, and can be used as natural preservatives and freshness-keeping agents to delay product spoilage; in the application in the field of cosmetics and personal care, they can scavenge skin free radicals, reduce wrinkles and age spots, inhibit scalp fungi, and inhibit oral pathogenic bacteria, etc.; for example, in the application in the field of medicine and health products, essential oils can replace antibiotics as natural antibacterial drugs, and for example, in the application in the agricultural field, essential oils can replace chemical pesticides to prevent and control plant diseases.

[0003] However, a single essential oil has an unsatisfactory antibacterial and antiseptic effect, and its antioxidant, antibacterial and bacteriostatic persistence and durability are poor, and a combination of multiple essential oils needs to be used to improve its bacteriostatic effect. However, when multiple bacteriostatic essential oils are combined, due to the large differences in properties between the components and their mutual influence, the stability of the combined essential oil is poor, and it is prone to layering, precipitation, etc., resulting in product failure and unsatisfactory durability. Summary of the Invention

[0004] The purpose of the present invention is to provide a plant compound essential oil.

[0005] Another purpose of the present invention is to provide a preparation method of a plant compound essential oil.

[0006] The purpose of the present invention is achieved through the following technical solutions: A preparation method of a plant compound essential oil, characterized by comprising the following steps: (1) Take lemon slices and freeze-dry them into dried lemon slices, and mix and crush the dried lemon slices, mint, and eagle tea into a mixed powder; (2) Place the mixed powder in a carbon dioxide supercritical extractor for extraction, and collect the extract; (3)Drop carboxymethyl-β-cyclodextrin solution into the mixture of eugenol and thymol, stir to form a suspension, and obtain an ultrasonic mixture through ultrasonic treatment. Let it stand and centrifuge to collect the supernatant, and obtain an inclusion compound in the form of a white powder through drying treatment; (4)Add lecithin, Tween 80, disodium pyrophosphate, and deionized water to the extract prepared in step (2). After heating and stirring, continue to add the inclusion compound in step (3), and obtain a nanoemulsion through homogenization treatment; (5)Add gelatin and propylene glycol to the nanoemulsion, heat and keep warm, and obtain a plant compound essential oil after cooling.

[0007] Furthermore, by weight, the amounts of each component used in the preparation process are 18 parts of eugenol, 10 - 12 parts of thymol, 10 - 15 parts of dried lemon slices, 5 - 8 parts of mint, 5 - 8 parts of eagle tea, 50 - 55 parts of carboxymethyl-β-cyclodextrin, 10 - 12 parts of gelatin, 5 - 7 parts of propylene glycol, 3 - 5 parts of Tween 80, 0.5 - 0.7 parts of disodium pyrophosphate, 12 - 15 parts of lecithin, and 20 - 30 parts of deionized water.

[0008] Furthermore, in step (1), the dried lemon slices are obtained by cleaning the lemons, cutting them into thick slices with a thickness of about 0.3 - 0.5 cm, and performing freeze-drying.

[0009] Furthermore, the freeze-drying is carried out by reducing the temperature at a rate of 5 - 7 °C / min to -18 - -22 °C, maintaining for 6 - 8 h, then evacuating to -0.05 - -0.08 MPa after qualitative determination, heating to -8 - -12 °C at a rate of 3 - 5 °C / min, keeping warm for 2 - 3 h, then heating to 12 - 15 °C within 1 - 2 h and keeping warm for 3 - 5 h, and then heating to 25 - 30 °C within 30 - 60 min and keeping warm for 6 - 8 h, and taking out to obtain the dried lemon slices.

[0010] Furthermore, in step (2), the extraction is carried out using propylene glycol, absolute ethanol, and deionized water as entrainers, setting the carbon dioxide flow rate to 12 - 15 kg / h, the pressure to 25 - 30 MPa, the temperature to 35 - 40 °C, and the extraction time to 2 - 4 h.

[0011] Furthermore, the mass ratio of propylene glycol, absolute ethanol, and deionized water in the entrainer is 3 - 5:15 - 20:70 - 75, and the mass ratio of the entrainer to the mixed powder is 1 - 2:1.

[0012] In the present invention, carbon dioxide fluid with relatively strong fat solubility is used as the extractant, and a water-soluble entrainer is selected. On the one hand, an ethanol solution is combined with propylene glycol and deionized water as the entrainer, which can enhance the penetration ability of the solvent into lemon slices, mint, and eagle tea, and strengthen the extraction efficiency. On the other hand, the water-soluble entrainer and carbon dioxide cooperate to limit the polarity distribution of the extracted target substances, achieving selective extraction of components with different polarities, thereby obtaining an extract with higher antibacterial activity.

[0013] Further, in the step (3), the carboxymethyl-β-cyclodextrin solution is obtained by mixing carboxymethyl-β-cyclodextrin and deionized water at a mass ratio of 1:10 - 15, and stirring and heating to 50 - 60 °C at 20 - 30 rpm.

[0014] Further, in the step (3), the stirring rate of the stirring is 20 - 30 rpm, and the stirring time is 15 - 20 min to obtain a suspension.

[0015] Further, in the step (3), the frequency of the ultrasonic treatment is 35 - 40 kHz, the temperature is 50 - 60 °C, and the ultrasonic treatment is carried out for 2 - 3 h to obtain an ultrasonic mixture.

[0016] Further, in the step (3), the static centrifugation is to cool the ultrasonic mixture to room temperature, then let it stand for 8 - 10 h, and then centrifuge at 8000 - 10000 rpm for 15 - 20 min to collect the supernatant.

[0017] Further, in the step (3), the drying treatment is to dry the supernatant at a vacuum degree of -0.05 MPa to -0.08 MPa and a drying temperature of 40 - 45 °C until constant weight to obtain a white powdery clathrate.

[0018] Further, in the step (4), the heating and stirring temperature is 30 - 40 °C, the stirring speed is 20 - 30 rpm, and the stirring time is 10 - 15 min.

[0019] Further, in the step (4), the homogenization is started at a homogenization speed of 2000 - 3000 rpm. After homogenizing for 5 - 10 min, the homogenization speed is increased to 5000 - 7000 rpm, and homogenization is continued for 3 - 5 min. Further, the homogenization speed is increased to 9000 - 10000 rpm, and homogenization is continued for 20 - 30 min to obtain a nanoemulsion.

[0020] Further, in the step (5), the heating and insulation is at a temperature of 40 - 45 °C, and stirring is carried out at 20 - 30 rpm for 2 - 3 h during the insulation process, and then it is naturally cooled to room temperature.

[0021] Most specifically, a method for preparing a plant compound essential oil, characterized by comprising the following steps: (1)Wash the lemon clean, cut it into thick slices with a thickness of about 0.3 - 0.5 cm, reduce the temperature to -18~-22°C at a cooling rate of 5~7°C / min, hold for 6~8 h, after qualitative analysis, evacuate to -0.05~-0.08 MPa, heat up to -8~-12°C at a rate of 3~5°C / min, keep warm for 2 - 3 h, then heat up to 12~15°C within 1~2 h and keep warm for 3 - 5 h, and then heat up to 25~30°C within 30 - 60 min and keep for 6~8 h to obtain dried lemon slices. Mix and crush the dried lemon slices, mint and hawthorn tea, and pass through a 12-mesh sieve to obtain a mixed powder; (2)Place the mixed powder in the extraction kettle of a supercritical carbon dioxide extraction instrument, add an entrainer, set the carbon dioxide flow rate to 12~15 kg / h, the pressure to 25~30 MPa, the temperature to 35~40°C, and the extraction time to 2~4 h. After the extraction is completed, collect the extract; the entrainer is composed of propylene glycol, absolute ethanol, and deionized water, with a mass ratio of 3~5:15~20:70~75, and the mass ratio of the mixed powder to the entrainer is 1:1~2; (3)Drop a 25%~30% carboxymethyl-β-cyclodextrin solution into the mixture of eugenol and thymol, stir at 20~30 rpm for 15~20 min to form a suspension, with an ultrasonic frequency of 35~40 kHz and a temperature of 50~60°C, and perform ultrasonic treatment for 2~3 h to obtain an ultrasonic mixture. After standing for 8~10 h, set the centrifugal speed to 8000 - 10000 rpm and centrifuge for 15~20 min, collect the supernatant, and dry the supernatant to constant weight under a vacuum of -0.05 MPa~-0.08 Mpa and a drying temperature of 40~45°C to obtain a white powdery inclusion compound; (4)Add lecithin, Tween 80, disodium pyrophosphate, and deionized water to the extract prepared in step (2), heat to 30~40°C, stir at 20~30 rpm for 15~20 min, and slowly add the white powdery inclusion compound prepared in step 4 under stirring conditions. After adding, continue to stir for 10~15 min, then place it in a high-speed homogenizer, start with a homogenization speed of 2000~3000 rpm, homogenize for 5~10 min, then increase the homogenization speed to 5000~7000 rpm, continue to homogenize for 3~5 min, and then increase the homogenization speed to 9000~10000 rpm and continue to homogenize for 20~30 min to obtain a nanoemulsion; (5)Stir and heat the nanoemulsion to 40~45°C at 20~30 rpm, add gelatin and propylene glycol, and continue to stir for 2~3 h under heat preservation conditions, then cool to room temperature to obtain a plant composite essential oil; The components used in the preparation process are as follows by weight: 15-20 parts of eugenol, 10-12 parts of thymol, 10-15 parts of lemon, 5-8 parts of mint, 5-8 parts of hawthorn tea, 50-55 parts of carboxymethyl-β-cyclodextrin, 10-12 parts of gelatin, 5-7 parts of propylene glycol, 3-5 parts of Tween 80, 0.5-0.7 parts of disodium pyrophosphate, 12-15 parts of lecithin, and 20-30 parts of deionized water.

[0022] Due to the adoption of a specific extraction process during extraction, the antibacterial active ingredients in the extract are increased, which can improve the antibacterial activity of the final preservative. However, due to the presence of water-soluble substances and fat-soluble substances in the extract, and the remaining active components eugenol and thymol are fat-soluble components, the mixing of various components with different properties is likely to cause component stratification, and fat-soluble components such as eugenol and thymol are prone to volatilization, oxidation, and hydrolysis. These factors lead to poor preservation persistence and durability of the preservation essential oil.

[0023] In the present invention, thymol and eugenol are included by carboxymethyl-β-cyclodextrin, and then together with the extract, they hydrate the lipid membrane to form liposomes, forming a dual loading of inclusion-membrane embedding of fat-soluble components, increasing the overall encapsulation efficiency of the liposomes. Carboxymethyl-β-cyclodextrin includes fat-soluble eugenol and thymol to form a pseudo-water-soluble complex. On the one hand, it can relieve their volatilization, and at the same time avoid their precipitation or aggregation due to low solubility in the aqueous phase. The hydrophilic carboxymethyl (-COO-) in carboxymethyl-β-cyclodextrin enriches in the aqueous environment of the liposomes, stabilizing the water-soluble components in the extract and inhibiting their phase separation from the fat-soluble components, reducing the problems of stratification and sedimentation. The water-soluble components are directly dissolved in the aqueous core of the liposomes. During use, the water-soluble components are preferentially released rapidly through the pore channels or rupture of the lipid membrane to achieve rapid onset. Secondly, the fat-soluble components in the extract are slowly released, and finally thymol and eugenol form a dual controlled release with the bilayer of the lipid membrane through the inclusion effect of carboxymethyl-β-cyclodextrin, forming a gradient release with different time effects and delaying the drug persistence of the active components.

[0024] During the formation of the antibacterial film, if the formed film is too hard, it is difficult to lock the moisture inside the film, and the antibacterial film is easily detached. If the film is too soft, it is easily damaged and deformed. In the present invention, gelatin and propylene glycol are used to form a film together. Gelatin plays a supporting role for the film formation of propylene glycol, and propylene glycol solves the problem that the film formed by gelatin is too hard and easily detached. The two complement each other, and finally form a continuous and smooth antibacterial film with appropriate hardness, effectively reducing the water loss of fruits and vegetables. The formation of the continuous antibacterial film enables the antibacterial nanoemulsion to adhere evenly inside it, further improving the antibacterial and anti-corrosion effects.

[0025] A plant compound essential oil, characterized in that: it is an extract obtained by supercritical carbon dioxide extraction of a mixed powder made from dried lemon slices, mint, and hawthorn tea. Eugenol and thymol are added to a carboxymethyl-β-cyclodextrin solution, and an inclusion complex is prepared by ultrasonic treatment. Lecithin, Tween 80, disodium pyrophosphate, and deionized water are added to the extract, and after heating and stirring, the inclusion complex is continuously added, and then homogenized to form a nanoemulsion. Gelatin and propylene glycol are added to the nanoemulsion, heated and kept warm, and after cooling, the plant compound essential oil is obtained.

[0026] Furthermore, by weight, the amounts of each raw material component in the fresh-keeping essential oil are 15 - 20 parts of eugenol, 10 - 12 parts of thymol, 10 - 15 parts of dried lemon slices, 5 - 8 parts of mint, 5 - 8 parts of hawthorn tea, 50 - 55 parts of carboxymethyl-β-cyclodextrin, 10 - 12 parts of gelatin, 5 - 7 parts of propylene glycol, 3 - 5 parts of Tween 80, 0.5 - 0.7 parts of disodium pyrophosphate, 12 - 15 parts of lecithin, and 20 - 30 parts of deionized water.

[0027] Furthermore, the extraction uses propylene glycol, absolute ethanol, and deionized water as entrainers, with a set carbon dioxide flow rate of 12 - 15 kg / h, a pressure of 25 - 30 MPa, a temperature of 35 - 40 °C, and an extraction time of 2 - 4 h.

[0028] Furthermore, the mass ratio of propylene glycol, absolute ethanol, and deionized water in the entrainer is 3 - 5:15 - 20:70 - 75, and the mass ratio of the entrainer to the mixed powder is 1 - 2:1.

[0029] Furthermore, the carboxymethyl-β-cyclodextrin solution is prepared by mixing carboxymethyl-β-cyclodextrin and deionized water at a mass ratio of 1:10 - 15, and stirring and heating at 20 - 30 rpm to 50 - 60 °C.

[0030] Furthermore, the ultrasonic treatment has a frequency of 35 - 40 kHz, a temperature of 50 - 60 °C, and is ultrasonically treated for 2 - 3 h to obtain an ultrasonic mixture.

[0031] Furthermore, the homogenization is started at a homogenization speed of 2000 - 3000 rpm. After homogenizing for 5 - 10 min, the homogenization speed is further increased to 5000 - 7000 rpm, and homogenization is continued for 3 - 5 min. Then, the homogenization speed is further increased to 9000 - 10000 rpm, and homogenization is continued for 20 - 30 min to obtain a nanoemulsion.

[0032] Furthermore, the heating and keeping warm is to stir and heat the nanoemulsion at 20 - 30 rpm to 40 - 45 °C, add gelatin and propylene glycol, and continue stirring for 2 - 3 h under the condition of keeping warm, and then naturally cool to room temperature.

[0033] The application of the above plant compound essential oil in the fresh-keeping of fruits and vegetables.

[0034] The present invention has the following technical effects: The plant composite essential oil of the present invention has antibacterial and antioxidant effects. In terms of antibacterial, it has strong antibacterial ability against Botrytis cinerea and Penicillium digitatum. In terms of antioxidant, the DPPH free radical scavenging rate is ≥90%. The present invention enables the active ingredients of the essential oil to be slowly released through the synergistic embedding of carboxymethyl-β-cyclodextrin wrapping and liposome by nano-embedding technology, effectively prolonging the antioxidant and antibacterial properties. Specific embodiments

[0035] The present invention will be specifically described below through examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0036] Example 1 A preparation method of a plant composite essential oil, comprising the following steps: (1) Take lemons, wash them clean, cut them into thick slices with a thickness of about 0.3 - 0.5 cm, reduce the temperature to -20°C at a cooling rate of 6°C / min, keep it for 7 h, evacuate to -0.05 - 0.08 MPa after qualitative analysis, heat up to -10°C at a rate of 4°C / min, keep warm for 2.5 h, then heat up to 14°C within 1.5 h and keep warm for 4 h, and then heat up to 30°C within 40 min and keep it for 6 h to obtain dried lemon slices. Mix 12 parts of the dried lemon slices, 6 parts of mint, and 6 parts of eagle tea and crush them, and sieve through a 12-mesh sieve to obtain a mixed powder; (2) Place the mixed powder in the extraction kettle of a carbon dioxide supercritical extraction instrument, add an entrainer, set the carbon dioxide flow rate to 14 kg / h, the pressure to 28 MPa, the temperature to 38°C, and the extraction time to 3 h. After the extraction is completed, collect the extract; the entrainer is composed of propylene glycol, absolute ethanol, and deionized water, with a mass ratio of 4:18:72, and the mass ratio of the mixed powder to the entrainer is 1:1.5; (3) Drop a 28% carboxymethyl-β-cyclodextrin solution by mass percentage into a mixture composed of 18 parts of eugenol and 10 parts of thymol, stir at 25 rpm for 18 min to form a suspension, with an ultrasonic frequency of 40 kHz and a temperature of 55°C, perform ultrasonic treatment for 1.5 h to obtain an ultrasonic mixture, let it stand for 9 h, then set the centrifugation speed to 9000 rpm, centrifuge for 18 min, collect the supernatant, and dry the supernatant to constant weight under a vacuum degree of -0.05 MPa - 0.08 MPa and a drying temperature of 45°C to obtain a white powdery inclusion compound; (4) Add 14 parts of lecithin, 4 parts of Tween 80, 0.6 part of disodium pyrophosphate, and 25 parts of deionized water to the extract prepared in step (2), heat to 35 °C, stir at 25 rpm for 18 min. Under stirring conditions, slowly add the white powdery clathrate prepared in step 4. After the addition is complete, continue stirring for 12 min, then place it in a high-speed homogenizer. First, start at a homogenization speed of 2500 rpm, homogenize for 8 min, then increase the homogenization speed to 6000 rpm, continue homogenizing for 4 min, then increase the homogenization speed to 9500 rpm, and continue homogenizing for 25 min to obtain a nanoemulsion; (5) Stir and heat the nanoemulsion to 40 °C at 25 rpm, add 10 parts of gelatin and 6 parts of propylene glycol, continue stirring for 2.5 h under heat preservation conditions, and cool to room temperature to obtain the plant compound essential oil; The parts by weight of the components used in the preparation process are based on parts by weight.

[0037] Comparative Example 1 Compared with Example 1, eugenol and thymol are not treated with carboxymethyl-β-cyclodextrin, but directly added together with the extract in step (4), and the remaining steps are the same as those in Example 1.

[0038] Comparative Example 2 Compared with Example 1, when preparing the clathrate in step (4), hydroxypropyl-β-cyclodextrin is used to replace carboxymethyl-β-cyclodextrin to clathrate eugenol and thymol, and the remaining steps are the same as those in Example 1.

[0039] Comparative Example 3 Compared with Example 1, glycerol is used to replace propylene glycol in step (5), and the remaining steps are the same as those in Example 1.

[0040] Antioxidant and antibacterial performance tests of each plant compound essential oil: (1) The plant compound essential oils prepared in Example 1 and each comparative example are tested by the DPPH free radical scavenging method. The specific operation steps are as follows: DPPH solution: Prepare a 0.1 mM DPPH solution with absolute ethanol (store in the dark).

[0041] Essential oil sample: Dissolve the essential oil with ethanol to prepare a 1 mg / mL sample solution.

[0042] Reaction: Take 0.1 mL of the sample solution + 2 mL of the DPPH solution, mix well and react in the dark for 30 min.

[0043] Detection: Using ethanol as a blank control, measure the absorbance at 517 nm (A 样品); simultaneously measure the absorbances of "sample + ethanol" (A0, excluding the interference of the sample's own color) and "DPPH + ethanol" (Acontrol).

[0044] Calculate the clearance rate:

[0045] (2) Test the long - acting antibacterial effect of each plant compound essential oil by the filter paper method. Measure the diameter of the antibacterial zone to reflect the antibacterial effect of the essential oil. The test bacteria are Botrytis cinerea ( Botrytis cinerea ), Penicillium expansum ( Penicillium expansum ): Immerse sterile filter paper with a diameter of 6 mm in essential oil ethanol solutions with different concentrations (the final concentration contains 2% ethanol) respectively. After draining, stick them on the PDA plate inoculated with the bacterial suspension (10 6 CFU / mL). After culturing at 25°C for 72 h, measure the diameter of the antibacterial zone, and repeat each group 3 times. The results of antioxidant and antibacterial properties are shown in Table 1.

[0046] Table 1:

[0047] It can be seen that the DPPH clearance rates of each group of plant compound essential oils all reach more than 90%. However, due to the differences in the release mechanisms of the active ingredients in the essential oils, there are significant differences in the antibacterial effects of each group of essential oils.

[0048] Divide the freshly picked strawberries into 6 groups. Among them, 5 groups are respectively sprayed with the fresh - keeping essential oils of Example 1 and each comparative example on the surface to ensure the same spraying amount. The remaining 1 group is sprayed with an equal amount of water. Then place the strawberries in a 4°C environment for cold storage. After 10 days, observe the mildew, water loss, and hardness of the strawberries. The results are shown in Table 2.

[0049] Table 2:

[0050] It can be seen that in Comparative Example 1, carboxymethyl - β - cyclodextrin was not used for prior embedding, and the effective fresh - keeping ingredients were only loaded by liposomes, unable to form a gradient for gradual release. The effective ingredients were rapidly released in the early stage of preservation. Compared with other comparative ratios, the fresh - keeping effect in the early stage was significantly excellent, but the fresh - keeping effect decreased significantly in the later stage, unable to achieve long - term fresh - keeping. In Comparative Example 2, hydroxypropyl - β - cyclodextrin was used to replace carboxymethyl - β - cyclodextrin. Due to the difference in the hydrophilicity of the groups, the synergistic effect with liposomes was not significant, resulting in a significant decrease in the overall fresh - keeping effect compared with Example 1. The fresh - keeping effect of Comparative Example 3 was not ideal, probably because of the poor structural performance of the antibacterial film.

[0051] In addition, the products of Example 1 and each comparative example were further sprayed onto the surface of bananas and placed in an environment at 25°C. After 28 days, the inhibitory effect on ripening between phases was detected. The results are shown in Table 3.

[0052] Table 3:

[0053] In order to study the influence of the extracts obtained under extraction conditions formed by different entrainers during the extraction process on the preservation performance of the final preservation essential oil, under the condition of the same amount of entrainer, the extracts obtained under different entrainer conditions were used to participate in the subsequent preparation of the preservation essential oil for strawberry preservation testing. Strawberries of the same batch were evenly divided into multiple groups, and each group was sprayed with the preservation essential oil corresponding to a different entrainer. In addition, the antioxidant properties of the essential oils corresponding to each group were further tested. The results are shown in Table 4.

[0054] Table 4:

[0055] In the above table, the "ethanol + acetone + deionized water" group is to replace propylene glycol with acetone in equal amounts. It can be seen that in the present invention, using ethanol + propylene glycol + deionized water as a composite entrainer, the overall preservation effect of the extracted active ingredients is more excellent. If any component is missing, the performance of the extracted active ingredients will decline, and its antioxidant effect will also decrease significantly.

[0056] Example 2 A method for preparing a plant composite essential oil, comprising the following steps: (1) Take lemons, wash them clean, cut them into thick slices with a thickness of about 0.3 - 0.5 cm, reduce the temperature to -18°C at a rate of 5°C / min, hold for 8 h, evacuate to -0.05 - 0.08 MPa after qualitative analysis, heat to -8°C at a rate of 3°C / min, hold for 3 h, then heat to 15°C within 2 h and hold for 3 h, and then heat to 30°C within 30 min and hold for 6 h to obtain dried lemon slices. Mix 10 parts of the dried lemon slices, 5 parts of mint, and 5 parts of eagle tea and crush them. Pass the crushed product through a 12-mesh sieve to obtain a mixed powder; (2) Place the mixed powder in the extraction kettle of a carbon dioxide supercritical extraction instrument, add an entrainer, set the carbon dioxide flow rate to 12 kg / h, the pressure to 30 MPa, the temperature to 35°C, and the extraction time to 4 h. After the extraction is completed, collect the extract; the entrainer is composed of propylene glycol, absolute ethanol, and deionized water, with a mass ratio of 3:15:70, and the mass ratio of the mixed powder to the entrainer is 1:1; (3) Add a 30% carboxymethyl-β-cyclodextrin solution by mass percentage dropwise to a mixture of 15 parts of eugenol and 10 parts of thymol, stir at 20 rpm for 20 min to form a suspension, with an ultrasonic frequency of 35 kHz and a temperature of 60 °C, perform ultrasonic treatment for 2 h to obtain an ultrasonic mixture, let it stand for 10 h, then set the centrifugation speed to 8000 rpm, centrifuge for 20 min, collect the supernatant, and dry the supernatant under a vacuum of -0.05 MPa to -0.08 Mpa and a drying temperature of 40 °C until constant weight is achieved to obtain a white powdery clathrate; (4) Add 12 parts of lecithin, 3 parts of Tween 80, 0.5 part of disodium pyrophosphate, and 20 parts of deionized water to the extract prepared in step (2), heat to 30 °C, stir at 20 rpm for 20 min, and slowly add the white powdery clathrate prepared in step 4 under stirring conditions. After adding, continue stirring for 10 min, then place it in a high-speed homogenizer. First, start with a homogenization speed of 2000 rpm, homogenize for 5 min, then increase the homogenization speed to 5000 rpm, continue homogenizing for 3 min, then increase the homogenization speed to 9000 rpm, and continue homogenizing for 20 min to obtain a nanoemulsion; (5) Stir and heat the nanoemulsion to 40 °C at 20 rpm, add 10 parts of gelatin and 5 parts of propylene glycol, continue stirring for 2 h under heat preservation conditions, and cool to room temperature to obtain a plant compound essential oil; Example 3 A preparation method of a plant compound essential oil, comprising the following steps: (1) Take a lemon, wash it clean, cut it into thick slices with a thickness of about 0.3 - 0.5 cm, reduce the temperature to -22 °C at a cooling rate of 7 °C / min, hold for 6 h, evacuate to -0.05 - 0.08 MPa after qualitative analysis, heat to -12 °C at a heating rate of 5 °C / min, hold for 2 h, then heat to 12 °C within 1 h and hold for 5 h, and then heat to 25 °C within 60 min and hold for 8 h to obtain dried lemon slices. Mix and crush 15 parts of the dried lemon slices, 8 parts of mint, and 8 parts of eagle tea, and pass through a 12-mesh sieve to obtain a mixed powder; (2) Place the mixed powder in the extraction kettle of a carbon dioxide supercritical extraction instrument, add an entrainer, set the carbon dioxide flow rate to 15 kg / h, the pressure to 25 MPa, the temperature to 40 °C, and the extraction time to 2 h. After the extraction is completed, collect the extract; the entrainer is composed of propylene glycol, absolute ethanol, and deionized water, with a mass ratio of 5:20:75, and the mass ratio of the mixed powder to the entrainer is 1:2; (3) Add a 25% (by mass) carboxymethyl-β-cyclodextrin solution dropwise to a mixture of 20 parts of eugenol and 12 parts of thymol, stir at 30 rpm for 15 min to form a suspension, with an ultrasonic frequency of 40 kHz and a temperature of 50 °C, subject to ultrasonic treatment for 3 h to obtain an ultrasonic mixture, let stand for 8 h, then set the centrifugation speed to 10,000 rpm, centrifuge for 15 min, collect the supernatant, and dry the supernatant to constant weight under a vacuum of -0.05 MPa to -0.08 MPa and a drying temperature of 45 °C to obtain a white powdery clathrate; (4) Add 15 parts of lecithin, 5 parts of Tween 80, 0.7 part of disodium pyrophosphate, and 30 parts of deionized water to the extract prepared in step (2), heat to 40 °C, stir at 30 rpm for 15 min, and slowly add the white powdery clathrate prepared in step 4 under stirring conditions. After adding, continue stirring for 10 - 15 min, then place it in a high-speed homogenizer. First, start with a homogenization speed of 3000 rpm, homogenize for 10 min, then increase the homogenization speed to 7000 rpm and continue homogenizing for 5 min, and then increase the homogenization speed to 10,000 rpm and continue homogenizing for 30 min to obtain a nanoemulsion; (5) Stir and heat the nanoemulsion to 45 °C at 30 rpm, add 12 parts of gelatin and 7 parts of propylene glycol, continue stirring for 3 h under heat preservation conditions, and let cool to room temperature to obtain the plant composite essential oil.

Claims

1. A preparation method of a plant compound essential oil, characterized in that It includes the following steps: (1) Take lemon slices and freeze-dry them into dried lemon slices, and then mix and crush the dried lemon slices, mint and hawthorn tea into a mixed powder; (2) Place the mixed powder in a supercritical carbon dioxide extraction instrument for extraction, and collect the extract; (3) Drop carboxymethyl-β-cyclodextrin solution into the mixture of eugenol and thymol, stir to form a suspension, perform ultrasonic treatment to obtain an ultrasonic mixture, let it stand and centrifuge to collect the supernatant, and perform drying treatment to obtain an inclusion complex in the form of a white powder; (4) Add lecithin, Tween 80, disodium pyrophosphate, and deionized water to the extract prepared in step (2), heat and stir, and then continue to add the inclusion complex in step (3), and perform homogenization treatment to obtain a nanoemulsion; (5) Add gelatin and propylene glycol to the nanoemulsion, heat and keep warm, and obtain a plant compound essential oil after cooling.

2. The preparation method of a plant compound essential oil according to claim 1, characterized in that: By weight, the amounts of each component used in the preparation process are 15-20 parts of eugenol, 10-12 parts of thymol, 10-15 parts of lemon, 5-8 parts of mint, 5-8 parts of hawthorn tea, 50-55 parts of carboxymethyl-β-cyclodextrin, 10-12 parts of gelatin, 5-7 parts of propylene glycol, 3-5 parts of Tween 80, 0.5-0.7 parts of disodium pyrophosphate, 12-15 parts of lecithin, and 20-30 parts of deionized water.

3. The preparation method of a plant compound essential oil according to claim 1 or 2, characterized in that: The extraction in step (2) uses propylene glycol, absolute ethanol and deionized water as entrainers, sets the carbon dioxide flow rate to 12-15 kg / h, the pressure to 25-30 MPa, the temperature to 35-40 °C, and the extraction time to 2-4 h.

4. The preparation method of a plant compound essential oil according to claim 3, characterized in that: The mass ratio of propylene glycol, absolute ethanol and deionized water in the entrainer is 3-5:15-20:70-75, and the mass ratio of the entrainer to the mixed powder is 1-2:

1.

5. The preparation method of a plant compound essential oil according to any one of claims 1-4, characterized in that: The carboxymethyl-β-cyclodextrin solution in step (3) is mixed according to the mass ratio of carboxymethyl-β-cyclodextrin to deionized water of 1:10-15, and stirred and heated to 50-60 °C at 20-30 rpm.

6. The preparation method of a plant compound essential oil according to claim 5, characterized in that: The frequency of ultrasonic treatment in step (3) is 35-40 kHz, the temperature is 50-60 °C, and ultrasonic treatment for 2-3 h obtains an ultrasonic mixture.

7. The preparation method of a plant compound essential oil according to any one of claims 1-6, characterized in that: The homogenization in step (4) starts at a homogenization speed of 2000-3000 rpm. After homogenization for 5-10 min, the homogenization speed is further increased to 5000-7000 rpm, and homogenization is continued for 3-5 min. Further, the homogenization speed is increased to 9000-10000 rpm, and homogenization is continued for 20-30 min to obtain a nanoemulsion.

8. The preparation method of a plant compound essential oil according to claim 7, characterized in that: The heating and heat preservation in step (5) is at a temperature of 40-45 °C, and during the heat preservation process, it is stirred at 20-30 rpm for 2-3 h, and then naturally cooled to room temperature.

9. A preparation method of a plant compound essential oil, characterized in that, It includes the following steps: (1)Wash the lemon clean, cut it into thick slices with a thickness of about 0.3 - 0.5 cm, reduce the temperature to -18 - -22 °C at a cooling rate of 5 - 7 °C / min, hold for 6 - 8 h, evacuate to -0.05 - -0.08 MPa after qualitative analysis, heat to -8 - -12 °C at a heating rate of 3 - 5 °C / min, keep warm for 2 - 3 h, then heat to 12 - 15 °C within 1 - 2 h and keep warm for 3 - 5 h, and then heat to 25 - 30 °C within 30 - 60 min and hold for 6 - 8 h to obtain dried lemon slices. Mix and crush the dried lemon slices, mint and eagle tea, and sieve through a 12-mesh sieve to obtain a mixed powder; (2)Place the mixed powder in the extraction kettle of a carbon dioxide supercritical extraction instrument, add an entrainer, set the carbon dioxide flow rate to 12 - 15 kg / h, the pressure to 25 - 30 MPa, the temperature to 35 - 40 °C, and the extraction time to 2 - 4 h. After the extraction is completed, collect the extract; the entrainer consists of propylene glycol, absolute ethanol, and deionized water, with a mass ratio of 3 - 5:15 - 20:70 - 75, and the mass ratio of the mixed powder to the entrainer is 1:1 - 2; (3)Drop the carboxymethyl-β-cyclodextrin solution into the mixture of eugenol and thymol, stir at 20 - 30 rpm for 15 - 20 min to form a suspension, with an ultrasonic frequency of 35 - 40 kHz and a temperature of 50 - 60 °C, and perform ultrasonic treatment for 2 - 3 h to obtain an ultrasonic mixture. After standing for 8 - 10 h, set the centrifugal speed to 8000 - 10000 rpm and centrifuge for 15 - 20 min, collect the supernatant, and dry the supernatant to constant weight under a vacuum of -0.05 MPa - -0.08 Mpa and a drying temperature of 40 - 45 °C to obtain a white powdery clathrate; (4)Add lecithin, Tween 80, disodium pyrophosphate, and deionized water to the extract prepared in step (2), heat to 30 - 40 °C, stir at 20 - 30 rpm for 15 - 20 min, and slowly add the white powdery clathrate prepared in step 4 under stirring conditions. After adding, continue to stir for 10 - 15 min, then place it in a high-speed homogenizer. First, start with a homogenization speed of 2000 - 3000 rpm and homogenize for 5 - 10 min, then increase the homogenization speed to 5000 - 7000 rpm and continue to homogenize for 3 - 5 min, and then increase the homogenization speed to 9000 - 10000 rpm and continue to homogenize for 20 - 30 min to obtain a nanoemulsion; (5)Stir and heat the nanoemulsion to 40 - 45 °C at 20 - 30 rpm, add gelatin and propylene glycol, and continue to stir for 2 - 3 h under warm conditions. Let it cool to room temperature to obtain a plant compound essential oil; The components used in the preparation process are as follows by weight: 15-20 parts of eugenol, 10-12 parts of thymol, 10-15 parts of lemon, 5-8 parts of mint, 5-8 parts of hawthorn tea, 50-55 parts of carboxymethyl-β-cyclodextrin, 10-12 parts of gelatin, 5-7 parts of propylene glycol, 3-5 parts of Tween 80, 0.5-0.7 parts of disodium pyrophosphate, 12-15 parts of lecithin, and 20-30 parts of deionized water.

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