Application of fat-soluble rosemary extract in preservation of walnut oil and preparation method of fat-soluble rosemary extract

Abstract

The invention relates to the field of plant product processing, and particularly discloses application of a fat-soluble rosemary extract in preservation of walnut oil and a preparation method of the fat-soluble rosemary extract. The rosemary leaves are dried, smashed and subjected to impurity removal treatment, rosemary leaf powder with high raw material purity is obtained, effective components in the rosemary leaf powder can be extracted in a concentrated mode, then extraction is conducted twice through a supercritical carbon dioxide extraction instrument, volatile oil and wax are removed through one-time extraction, and then the effective components in the rosemary leaf powder are extracted through another-time extraction; the preparation method comprises the following steps: extracting the walnut oil by using a two-stage separation kettle to improve the purity of a secondary extraction product, treating the secondary extraction product by using a two-stage separation kettle to obtain a terpene light component and a fat-soluble antioxidant component, and adding the terpene light component and the fat-soluble antioxidant component into the walnut oil to effectively improve the antioxidant performance of the walnut oil.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant product processing, and specifically relates to the application of fat-soluble rosemary extract in walnut oil preservation and its preparation method. Background Art

[0002] Walnut oil is rich in unsaturated fatty acids such as linoleic acid and linolenic acid, and is easily affected by factors such as light, heat, and oxygen, resulting in oxidative rancidity and a decline in quality. To extend the shelf life of walnut oil, an appropriate amount of antioxidant needs to be added to the walnut oil. However, traditional synthetic antioxidants such as butylated hydroxytoluene and tert-butylhydroquinone have potential health risks, while the stability of natural antioxidants such as vitamin E in walnut oil is insufficient. It can be seen that the existing antioxidants cannot meet the preservation and use requirements of walnut oil.

[0003] In long-term research and exploration, researchers found that various substances in rosemary have strong antioxidant activities, such as carnosic acid and rosmarinic acid. Therefore, production personnel will extract various substances from rosemary and then mix the extracted substances into walnut oil as antioxidants. However, in the actual manufacturing process, the solubility of these extracts in the oil system is poor, and they cannot be evenly dispersed in the walnut oil system, resulting in an insignificant improvement in the antioxidant performance of walnut oil. Summary of the Invention

[0004] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide the application of fat-soluble rosemary extract in walnut oil preservation and its preparation method, so as to solve the problem that the rosemary extract prepared by the existing process is not significantly dispersed in walnut oil and cannot significantly improve the antioxidant performance of walnut oil.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A preparation method of fat-soluble rosemary extract, the steps include:

[0007] Select mature and fresh leaves during the flowering period of rosemary, dry and crush them, and obtain rosemary leaf powder after removing impurities from the crushed product;

[0008] Use a supercritical carbon dioxide extraction instrument to process the rosemary leaf powder to obtain a separated extract;

[0009] Process the separated extract with a short-path molecular distillation instrument to obtain fat-soluble rosemary extract, add 0.1% tocopherol to the fat-soluble rosemary extract, and then store it in a nitrogen-filled, sealed, and light-proof manner.

[0010] Preferably, in the drying and pulverizing process, the leaves are dried with hot air circulation at 40 - 50 °C until the water content is less than 8%, and then pulverized to 60 - 80 mesh with a low-temperature pulverizer at a temperature less than 10 °C. The stem fragments in the pulverized leaf material are removed using a vibrating sieve to obtain rosemary leaf powder.

[0011] Preferably, the rosemary leaf powder is processed with a supercritical carbon dioxide extractor to obtain a separated extract. The rosemary leaf powder is placed in the supercritical carbon dioxide extractor for two extractions. The conditions for the first extraction are set as a pressure of 15 - 20 MPa, a temperature of 35 - 40 °C, a CO2 flow rate of 15 - 20 L / h, and the extraction time is 0.5 hour. The conditions for the second extraction are adjusted to a pressure of 30 - 35 MPa, a temperature of 45 - 50 °C, a CO2 flow rate of 25 - 30 L / h, and 5% - 8% by mass of entrainer is added to the rosemary leaf powder, and the extraction time is 2 - 3 hours. The extraction product is separated twice using a separation kettle to obtain a separated extract.

[0012] Preferably, the entrainer is formed by mixing ethanol and n-hexane in a volume ratio of 1:3.

[0013] Preferably, the extraction product is separated twice using a separation kettle. The conditions for the first separation are a pressure of 10 MPa and a temperature of 50 °C to collect the terpene light components. The conditions for the second separation are a pressure of 5 MPa and a temperature of 35 °C to collect the fat-soluble antioxidants.

[0014] Preferably, in the process of treating the separated extract with a short-path molecular distillation apparatus, the treatment conditions of the short-path molecular distillation apparatus are set as an evaporation temperature of 60 - 65 °C, a condensation temperature of 20 - 25 °C, and a vacuum degree of 0.05 - 0.1 mbar. The treatment is stopped when the content of carnosic acid in the separated extract is ≥40%, rosmarinol ≥15%, and the total phenol content ≥60% to obtain a fat-soluble rosemary extract.

[0015] The fat-soluble rosemary extract is prepared by the preparation method of the fat-soluble rosemary extract.

[0016] The application of the fat-soluble rosemary extract in the preservation of walnut oil is specifically as follows:

[0017] The fat-soluble rosemary extract, vitamin E, and citric acid are prepared into a compound additive according to a mass ratio of 5:5:1;

[0018] The compound additive is mixed with walnut oil according to a mass ratio of 0.1:99.9 and stirred at 40 - 50 °C for 30 minutes until completely dissolved.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] In the preparation process disclosed by the present invention, through drying, pulverizing and impurity removing treatment of rosemary leaves, rosemary leaf powder with relatively high raw material purity is obtained, which helps to concentrate the extraction of effective components in the rosemary leaf powder. Then, a supercritical carbon dioxide extractor is used for extraction in two times. The first extraction removes volatile oils and waxes to improve the purity of the product obtained by the second extraction. Then, the product obtained by the second extraction is processed by a two-stage separation kettle to obtain terpene light components and fat-soluble antioxidant components. Adding this component to walnut oil can effectively improve the antioxidant performance of walnut oil. Brief Description of the Drawings

[0021] Figure 1 It is a block diagram of the preparation method of the fat-soluble rosemary extract of the present invention. Detailed Embodiments

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] Embodiment 1:

[0024] Please refer to Figure 1 As shown, the preparation method of the fat-soluble rosemary extract includes the following steps:

[0025] Select mature and fresh leaves during the flowering period of rosemary, dry and pulverize them, and obtain rosemary leaf powder after impurity removing of the pulverized product;

[0026] Use a supercritical carbon dioxide extractor to process the rosemary leaf powder to obtain a separated extract;

[0027] Use a short-path molecular distillation instrument to process the separated extract to obtain a fat-soluble rosemary extract, add 0.1% tocopherol as a stabilizer to the fat-soluble rosemary extract, and then store it in a nitrogen-filled, sealed and light-proof manner.

[0028] As can be seen from the above, through drying, pulverizing and impurity removing treatment of rosemary leaves, rosemary leaf powder with relatively high raw material purity is obtained, which helps to concentrate the extraction of effective components in the rosemary leaf powder. Then, the rosemary leaf powder is extracted in two times by using a supercritical carbon dioxide extractor. The first extraction removes volatile oils and waxes to improve the purity of the product obtained by the second extraction. Then, the product obtained by the second extraction is processed by a two-stage separation kettle to obtain terpene light components and fat-soluble antioxidant components. Adding this component to walnut oil can effectively improve the antioxidant performance of walnut oil.

[0029] The fat-soluble rosemary extract is prepared by the preparation method of the fat-soluble rosemary extract.

[0030] The application of the fat-soluble rosemary extract in the preservation of walnut oil is specifically as follows:

[0031] Prepare a compound additive by mixing the fat-soluble rosemary extract, vitamin E, and citric acid in a mass ratio of 5:5:1. Vitamin E can block the lipid peroxidation chain reaction, and citric acid can chelate metal ions, thereby inhibiting the oxidation catalytic reaction. The combined effect can significantly improve the antioxidant performance of walnut oil.

[0032] Mix the compound additive with walnut oil in a mass ratio of 0.1:99.9 and stir at 40 - 50 °C for 30 minutes until completely dissolved.

[0033] Example two:

[0034] Please refer to Figure 1 As shown, the preparation method of the fat-soluble rosemary extract includes the following steps:

[0035] Select mature fresh leaves during the flowering period of rosemary, dry and crush them, and obtain rosemary leaf powder after removing impurities from the crushed product.

[0036] Use a supercritical carbon dioxide extraction instrument to process the rosemary leaf powder to obtain a separated extract.

[0037] Use a short-path molecular distillation instrument to process the separated extract to obtain the fat-soluble rosemary extract. Add 0.1% tocopherol as a stabilizer to the fat-soluble rosemary extract, and then store it in a nitrogen-filled, sealed, and light-proof manner.

[0038] As can be seen from the above, by drying, crushing, and removing impurities from rosemary leaves, rosemary leaf powder with a higher raw material purity is obtained, which helps to concentrate the active ingredients in the rosemary leaf powder. Then, use a supercritical carbon dioxide extraction instrument to extract the rosemary leaf powder twice. The first extraction removes volatile oils and waxes to improve the purity of the product obtained from the second extraction. Then, process the product obtained from the second extraction through two-stage separation tanks to obtain terpene light components and fat-soluble antioxidant components. Adding this component to walnut oil can effectively improve the antioxidant performance of walnut oil.

[0039] In the drying and crushing process, use hot air circulation at 40 - 50 °C to dry the leaves until the water content is less than 8%. Use a low-temperature crusher with a temperature less than 10 °C to crush the dried leaves to 60 - 80 mesh to avoid the degradation of active ingredients in rosemary caused by high temperature. Use a vibrating screen to remove the stem fragments from the crushed leaf material to obtain rosemary leaf powder with a higher purity.

[0040] The rosemary leaf powder is processed by a supercritical carbon dioxide extractor to obtain a separated extract. The rosemary leaf powder is placed in the supercritical carbon dioxide extractor for two extractions. The conditions of the first extraction are set as a pressure of 15 - 20 MPa, a temperature of 35 - 40 °C, a CO2 flow rate of 15 - 20 L / h, and extraction for 0.5 hours, which can remove the volatile oils and waxes in the rosemary leaf powder. The conditions of the second extraction are adjusted to a pressure of 30 - 35 MPa, a temperature of 45 - 50 °C, a CO2 flow rate of 25 - 30 L / h, and 5% - 8% by mass of an entrainer is added to the rosemary leaf powder. The entrainer is formed by mixing ethanol and n - hexane in a volume ratio of 1:3, and extraction is carried out for 2 - 3 hours. The extraction product is separated twice using a separation kettle to obtain a separated extract.

[0041] The extraction product is separated twice using a separation kettle. The conditions of the first separation are a pressure of 10 MPa and a temperature of 50 °C to collect the light terpene components. The conditions of the second separation are a pressure of 5 MPa and a temperature of 35 °C to collect the fat - soluble antioxidants.

[0042] The fat - soluble rosemary extract is prepared by the preparation method of the fat - soluble rosemary extract.

[0043] The application of the fat - soluble rosemary extract in the preservation of walnut oil is as follows:

[0044] The fat - soluble rosemary extract, vitamin E, and citric acid are prepared into a compound additive according to a mass ratio of 5:5:1. Vitamin E can block the lipid peroxidation chain reaction, and citric acid can chelate metal ions, thereby inhibiting the oxidation - catalyzed reaction. The combined effect can significantly improve the antioxidant performance of walnut oil.

[0045] The compound additive and walnut oil are mixed according to a mass ratio of 0.1:99.9 and stirred at 40 - 50 °C for 30 minutes until completely dissolved.

[0046] Example three:

[0047] Please refer to Figure 1 As shown, the preparation method of the fat - soluble rosemary extract includes the steps of:

[0048] Select the mature and fresh leaves of rosemary during the flowering period, dry and crush them. After removing impurities from the crushed product, rosemary leaf powder is obtained.

[0049] The rosemary leaf powder is processed by a supercritical carbon dioxide extractor to obtain a separated extract.

[0050] The separated extract is processed by a short - path molecular distillation instrument to obtain a fat - soluble rosemary extract. 0.1% of tocopherol is added to the fat - soluble rosemary extract as a stabilizer, and then it is filled with nitrogen, sealed, and stored away from light.

[0051] As can be seen from the above, by drying, pulverizing, and removing impurities from rosemary leaves, rosemary leaf powder with a relatively high raw material purity is obtained, which helps to concentrate the extraction of the active ingredients in the rosemary leaf powder. Subsequently, a supercritical carbon dioxide extractor is used to extract the rosemary leaf powder in two stages. The first extraction removes volatile oils and waxes to improve the purity of the product obtained from the second extraction. Then, the product obtained from the second extraction is processed through two-stage separation vessels to obtain terpene light components and fat-soluble antioxidant components. Adding these components to walnut oil can effectively improve the antioxidant performance of walnut oil.

[0052] In the drying and pulverizing process, the leaves are dried with hot air circulation at 40 - 50 °C until the water content is lower than 8%. A low-temperature pulverizer with a temperature below 10 °C is used to pulverize the dried leaves to 60 - 80 mesh, avoiding the degradation of active ingredients in rosemary due to high temperature. A vibrating screen is used to remove the stem fragments from the pulverized leaf material to obtain rosemary leaf powder with a relatively high purity.

[0053] When using a supercritical carbon dioxide extractor to process the rosemary leaf powder to obtain a separated extract, the rosemary leaf powder is placed in the supercritical carbon dioxide extractor for two extractions. The environmental conditions for the first extraction are set as a pressure of 15 - 20 MPa, a temperature of 35 - 40 °C, a CO2 flow rate of 15 - 20 L / h, and an extraction time of 0.5 hours, which can remove the volatile oils and waxes in the rosemary leaf powder. The environmental conditions for the second extraction are adjusted to a pressure of 30 - 35 MPa, a temperature of 45 - 50 °C, a CO2 flow rate of 25 - 30 L / h, and 5% - 8% by mass of an entrainer is added to the rosemary leaf powder. The entrainer is formed by mixing ethanol and n-hexane in a volume ratio of 1:3, and the extraction is carried out for 2 - 3 hours. The extraction product is separated twice using a separation vessel to obtain a separated extract.

[0054] When using the separation vessel to separate the extraction product twice, the conditions for the first separation are a pressure of 10 MPa and a temperature of 50 °C to collect the terpene light components, and the conditions for the second separation are a pressure of 5 MPa and a temperature of 35 °C to collect the fat-soluble antioxidants.

[0055] When using a short-path molecular distillation apparatus to process the separated extract, the processing conditions of the short-path molecular distillation apparatus are set as an evaporation temperature of 60 - 65 °C, a condensation temperature of 20 - 25 °C, and a vacuum degree of 0.05 - 0.1 mbar, which is used to remove the residual solvents and low-molecular-weight impurities in the separated extract. The processing stops when the content of carnosic acid in the separated extract is ≥ 40%, rosmarinol ≥ 15%, and the total phenol content ≥ 60%. High-performance liquid chromatography can be used to quantitatively analyze the content of each component in the separated extract, so as to obtain the accurate content of each component, facilitating the processing personnel to understand the processing progress in real time. After processing, a fat-soluble rosemary extract is obtained.

[0056] A fat-soluble rosemary extract, prepared by a method for preparing a fat-soluble rosemary extract.

[0057] Application of the fat-soluble rosemary extract in preserving walnut oil, specifically:

[0058] Prepare a compound additive by mixing the fat-soluble rosemary extract, vitamin E, and citric acid in a mass ratio of 5:5:1. Vitamin E can block the lipid peroxidation chain reaction, and citric acid can chelate metal ions, thereby inhibiting the oxidation catalytic reaction. The combined effect can significantly improve the antioxidant performance of walnut oil.

[0059] Mix the compound additive with walnut oil in a mass ratio of 0.1:99.9 and stir for 30 minutes at 40 - 50 °C until completely dissolved.

[0060] Example 4:

[0061] Please refer to Figure 1 As shown, the preparation method of the fat-soluble rosemary extract includes the following steps:

[0062] Select mature and fresh leaves during the flowering period of rosemary, dry them and then crush them. After removing impurities from the crushed product, obtain rosemary leaf powder.

[0063] Use a supercritical carbon dioxide extraction instrument to process the rosemary leaf powder to obtain a separated extract.

[0064] Use a short-path molecular distillation instrument to process the separated extract to obtain a fat-soluble rosemary extract. Add 0.1% tocopherol as a stabilizer to the fat-soluble rosemary extract and then store it in a nitrogen-filled, sealed, and light-proof manner.

[0065] As can be seen from the above, by drying, crushing, and removing impurities from rosemary leaves, rosemary leaf powder with a higher raw material purity is obtained, which helps to concentrate the active ingredients in the rosemary leaf powder. Then, use a supercritical carbon dioxide extraction instrument to extract the rosemary leaf powder twice. The first extraction removes volatile oils and waxes to improve the purity of the product obtained from the second extraction. Then, process the product obtained from the second extraction through two-stage separation kettles to obtain terpene light components and fat-soluble antioxidant components. Adding this component to walnut oil can effectively improve the antioxidant performance of walnut oil.

[0066] In the drying and crushing process, use hot air circulation at 40 - 50 °C to dry the leaves until the water content is lower than 8%. Use a low-temperature crusher with a temperature less than 10 °C to crush the dried leaves to 60 - 80 mesh to avoid degradation of the active ingredients in rosemary due to high temperature. Use a vibrating screen to remove the stem fragments in the leaf crushed material to obtain rosemary leaf powder with a higher purity.

[0067] The rosemary leaf powder is processed with a supercritical carbon dioxide extractor to obtain a separated extract. The rosemary leaf powder is placed in the supercritical carbon dioxide extractor for two extractions. The environmental conditions for the first extraction are set as a pressure of 15 - 20 MPa, a temperature of 35 - 40 °C, a CO2 flow rate of 15 - 20 L / h, and the extraction is carried out for 0.5 hours, which can remove the volatile oils and waxes in the rosemary leaf powder. The environmental conditions for the second extraction are adjusted to a pressure of 30 - 35 MPa, a temperature of 45 - 50 °C, a CO2 flow rate of 25 - 30 L / h, and an entrainer with a mass fraction of 5% - 8% is added to the rosemary leaf powder. The entrainer is formed by mixing ethanol and n - hexane in a volume ratio of 1:3, and the extraction is carried out for 2 - 3 hours. The extraction product is separated twice using a separation kettle to obtain a separated extract.

[0068] When using the separation kettle to separate the extraction product twice, the conditions for the first separation are a pressure of 10 MPa and a temperature of 50 °C to collect the terpene light components, and the conditions for the second separation are a pressure of 5 MPa and a temperature of 35 °C to collect the fat - soluble antioxidants.

[0069] When processing the separated extract with a short - path molecular distillation instrument, the processing conditions of the short - path molecular distillation instrument are set as an evaporation temperature of 60 - 65 °C, a condensation temperature of 20 - 25 °C, and a vacuum degree of 0.05 - 0.1 mbar, which is used to remove the residual solvents and low - molecular - weight impurities in the separated extract. The processing stops when the content of carnosic acid in the separated extract is ≥40%, the content of rosmarinol is ≥15%, and the total phenol content is ≥60%. The content of each component in the separated extract can be quantitatively analyzed by high - performance liquid chromatography, so as to obtain the accurate content of each component, which is convenient for the processing personnel to understand the processing progress in real time. After processing, a fat - soluble rosemary extract is obtained.

[0070] The fat - soluble rosemary extract is prepared by the preparation method of the fat - soluble rosemary extract.

[0071] The application of the fat - soluble rosemary extract in the preservation of walnut oil is as follows:

[0072] The fat - soluble rosemary extract, vitamin E, and citric acid are prepared into a compound additive according to a mass ratio of 5:5:1. Vitamin E can block the lipid peroxidation chain reaction, and citric acid can chelate metal ions, thereby inhibiting the oxidation catalytic reaction. The combined effect can significantly improve the antioxidant performance of walnut oil;

[0073] The compound additive is mixed with walnut oil according to a mass ratio of 0.1:99.9 and stirred at 40 - 50 °C for 30 minutes until completely dissolved.

[0074] In another addition method, the extract can be mixed with a small amount of walnut oil to form a concentrated mother liquor, and then the concentrated mother liquor is dispersed into the total amount of oil.

[0075] In another addition method, the spray drying method can be used to prepare microcapsules of fat-soluble extracts with an encapsulation rate of ≥85% using β-cyclodextrin as the wall material. Adding them to walnut oil to slowly release antioxidant components can effectively extend the release time of the fat-soluble extracts, thereby extending the action time of the fat-soluble rosemary extracts and further extending the antioxidant performance of walnut oil.

[0076] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The meaning of "a plurality" is two or more unless otherwise specifically defined.

[0077] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher level height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower level height than the second feature.

[0078] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not have to be directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0079] In the attached drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved, and other structures can refer to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

Claims

1. A method for preparing a fat-soluble rosemary extract, characterized in that the steps include: Selecting mature fresh leaves of rosemary in the flowering period, drying and then crushing, and removing impurities from the crushed product to obtain rosemary leaf powder; Using a supercritical carbon dioxide extractor to process rosemary leaf powder to obtain an isolated extract; The separated extract is treated with a short-range molecular distillation apparatus to obtain a fat-soluble rosemary extract, 0.1% tocopherol is added to the fat-soluble rosemary extract, and then the extract is filled with nitrogen, sealed and stored away from light.

2. The method for preparing the fat-soluble rosemary extract according to claim 1, wherein: In the post-drying pulverization, the leaves are dried by circulating hot air at 40-50° C. until the moisture content is less than 8%, the dried leaves are pulverized into 60-80 meshes by a low-temperature pulverizer at a temperature less than 10° C., and the stem fragments in the leaf pulverizer are removed by a vibrating screen to obtain rosemary leaf powder.

3. The method for preparing the fat-soluble rosemary extract according to claim 1, wherein: The method uses a supercritical carbon dioxide extractor to process rosemary leaf powder to obtain a separated extract. The rosemary leaf powder is placed in the supercritical carbon dioxide extractor for two extractions, wherein the first extraction environment conditions are set to a pressure of 15-20MPa, a temperature of 35-40°C, a CO2 flow rate of 15-20L / h, and the extraction is performed for 0.5 hour. The second extraction environment conditions are adjusted to a pressure of 30-35MPa, a temperature of 45-50°C, and a CO2 flow rate of 25-30L / h. An entrainer with a mass fraction of 5% to 8% is added to the rosemary leaf powder, and the extraction is performed for 2-3 hours. A separation kettle is used to separate the extracted product twice to obtain a separated extract.

4. The method for preparing the fat-soluble rosemary extract according to claim 3, wherein: The entrainer is formed by mixing ethanol and n-hexane in a volume ratio of 1:

3.

5. The method for preparing the fat-soluble rosemary extract according to claim 3, characterized in that: The separation kettle is used to separate the extraction product twice, the first separation condition is 10MPa pressure and 50°C temperature to collect terpene light components, and the second separation condition is 5MPa pressure and 35°C temperature to collect fat-soluble antioxidants.

6. The method for preparing the fat-soluble rosemary extract according to claim 1, characterized in that: In the process of using a short-range molecular distillation apparatus to process the separated extract, the processing conditions of the short-range molecular distillation apparatus are set to an evaporation temperature of 60-65° C., a condensation temperature of 20-25° C., and a vacuum degree of 0.05-0.1 mbar. When the content of carnosic acid in the separated extract is ≥40%, the content of rosmarinol is ≥15%, and the content of total phenols is ≥60%, the processing is stopped to obtain a fat-soluble rosemary extract.

7. A fat-soluble rosemary extract, characterized in that The fat-soluble rosemary extract is prepared by the preparation method of any one of claims 1 to 6.

8. The use of the fat-soluble rosemary extract according to claim 7 in preserving walnut oil, characterized in that: Specifically: The fat-soluble rosemary extract, vitamin E and citric acid are prepared into a composite additive in a mass ratio of 5:5:1; Mix the compound additive and walnut oil in a mass ratio of 0.1:99.9, and stir at 40-50°C for 30 minutes until they are completely dissolved.

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