Extraction method of carrot leaf oil and carrot leaf powder

Abstract

The invention relates to the field of food deep processing, and particularly discloses an extraction method of carrot leaf oil and carrot leaf powder.The extraction method of the carrot leaf oil comprises the following steps that S1, carrot leaves are sorted, selected, cleaned, ground and pulped, and carrot leaf pulp is obtained; s2, performing vacuum freeze drying on the carrot leaf pulp, and crushing to obtain a carrot leaf pulp freeze-dried substance; s3, performing supercritical CO2 extraction on the freeze-dried carrot leaf pulp to extract carrot leaf oil and carrot leaf residues; drying, crushing and sieving the carrot leaf residues to obtain carrot leaf powder; the utilization rate and the eating rate of the carrot leaves are improved, and the extraction rate of the carrot leaf oil is improved, so that the high-value utilization of the carrots is improved.

Description

Technical Field

[0001] This application relates to the field of deep food processing, and more specifically, it relates to a method for extracting carrot leaf oil and carrot leaf powder. Background Technology

[0002] Carrots are a typical biennial umbelliferous crop, and in my country, they have formed three major producing areas in North China, Northwest China and Northeast China. In 2024, the planting area reached 468,000 hectares. After the fleshy root is harvested, each hectare produces about 12-15 tons of fresh leaf by-products. The national annual output exceeds 5 million tons, and the current comprehensive utilization rate is less than 20%.

[0003] Carrot leaves are a high-value agricultural byproduct, containing volatile active ingredients such as α-pinene, β-pinene, and limonene, exhibiting significant antioxidant and antibacterial activities. The volatile components in carrot leaves have a feeding rejection rate of over 65% against aphids, reducing pesticide application during cultivation by 83% compared to conventional leafy vegetables. Therefore, carrot leaves are an ideal green food ingredient. Furthermore, carrot leaves are rich in vitamins, especially vitamin K (120 μg / 100g, approximately 1.5% proanthocyanidins), calcium, pectin, flavonoids, and polyphenols. These active ingredients endow them with various physiological functions such as antioxidation and antibacterial properties, giving carrot leaves significant nutritional value and health benefits.

[0004] Currently, carrot leaves are not widely consumed due to the presence of special volatile oils and active substances, which makes them less palatable. Moreover, they are not widely accepted as a vegetable for cooking. However, it is undeniable that carrot leaves are an ideal food ingredient from both a nutritional and low-pesticide-use perspective.

[0005] Therefore, how to improve the utilization and consumption rate of carrot leaves and enhance their high-value utilization is an urgent problem to be solved. Summary of the Invention

[0006] In order to improve the utilization and consumption rate of carrot leaves and enhance their high-value utilization, this application provides a method for extracting carrot leaf oil and carrot leaf powder.

[0007] In a first aspect, this application provides a method for extracting carrot leaf oil, employing the following technical solution: A method for extracting carrot leaf oil includes the following steps: S1. After sorting, selecting, washing, grinding and pulping the carrot leaves, carrot leaf pulp is obtained. S2. The carrot leaf slurry is vacuum freeze-dried and pulverized to obtain freeze-dried carrot leaf slurry; S3. The freeze-dried carrot leaf pulp was extracted with supercritical CO2 to obtain carrot leaf oil, yielding carrot leaf residue.

[0008] By adopting the above technical solution, carrot leaves are selected, pulped, dried, freeze-dried, and finally supercritically extracted to obtain carrot leaf oil and carrot leaf residue. The volatile active ingredients of carrot leaf oil can be used in the fields of medicine, agriculture, and food, while carrot leaf residue can also be processed and mixed with flour and other substances to prepare food, thereby improving the utilization rate and edibility of carrot leaves and thus increasing the high-value utilization of carrot leaves.

[0009] After washing, carrot leaves are ground and pulped to break down the cellulose cell walls, exposing the oil glands and facilitating subsequent extraction of carrot leaf oil. The carrot leaf pulp is then vacuum freeze-dried and pulverized. The growth of ice crystals, combined with the crushing process, further damages the cells. Freeze-drying also prevents the oxidation and pyrolysis of volatile oils, preserving the active volatile components in the carrot leaf oil. During freeze-drying, the sublimation of ice crystals forms honeycomb-like micropores, facilitating rapid CO2 diffusion during supercritical extraction and reducing diffusion resistance. Combined with the damaged cells, this further promotes the extraction of active volatile components, increasing the extraction rate of carrot leaf oil.

[0010] Carrot leaf residue contains fiber and pigments. Vacuum freeze-drying is used to prevent chlorophyll degradation. After drying, chlorophyll molecules are locked in the dry matrix, reducing their migration activity. Supercritical CO2 extraction is used to retain a high chlorophyll content in carrot leaf residue. Combined with its high cellulose content, this increases the nutritional value of carrot leaf residue and enhances its application in the food industry.

[0011] Preferably, during the grinding and pulping process in S1, liquid nitrogen is added to control the temperature at 2-4℃.

[0012] By adopting the above technical solution and adding liquid nitrogen to control the temperature, the active ingredients of the volatile oil are not easily lost, and the carotene is not easily degraded. After being treated with liquid nitrogen at a limited temperature, the volatile oil of carrot leaves is more easily extracted, thus increasing the processing rate.

[0013] Preferably, the carrot leaf slurry in S2 is pretreated before vacuum freeze-drying. The specific pretreatment steps are as follows: 0.5-0.7% citric acid is added to the carrot leaf slurry, and it is frozen at -12℃ to -10℃ for 8-12 hours to obtain pre-frozen material, thus completing the pretreatment.

[0014] By adopting the above technical solution, adding 0.5-0.7% citric acid creates an acidic environment, inhibits the activity of polyphenol oxidase, and blocks the enzymatic browning reaction. At the same time, citric acid acts as a metal ion chelating agent, reducing the catalytic effect of iron, copper and other ions on the oxidation of carotene and maintaining the color stability of the oil. Furthermore, low-temperature freezing causes the slurry water to slowly form large-sized ice crystals. The expansion process of the ice crystals mechanically tears the plant cell walls and oil cell membrane structure, releasing intracellular fat-soluble components and improving the extraction rate of volatile oil from carrot leaves.

[0015] The ice crystal skeleton formed during freezing supports the porous structure of the freeze-dried carrot leaf pulp, which facilitates the sublimation path during vacuum drying and shortens the drying time. The acidic conditions maintained by citric acid reduce the loss of heat-sensitive components (such as vitamin C) at high temperatures and result in a high retention rate of carotenoids, thus giving the carrot leaf residue a high nutrient retention rate.

[0016] Preferably, the specific steps of vacuum freeze-drying of carrot leaf slurry in S2 are as follows: the pre-frozen material is freeze-dried under the conditions of freeze-drying pressure of 30-50 Pa, freeze-drying time of 3-5 h, and shelf temperature of 8-10 °C.

[0017] Preferably, after drying, the material is then pulverized at low temperature, with liquid nitrogen used to assist the pulverization process. The pulverization temperature is 4-20℃ to obtain freeze-dried carrot leaf pulp.

[0018] By adopting the above technical solution, under extremely low pressure of 30-50Pa, the ice crystals formed by pre-freezing directly sublimate. After the ice crystals disappear in situ, they form a network of interconnected micropores, which significantly increases the specific surface area of ​​the material. This creates an efficient permeation channel for the extraction solvent, shortens the solvent diffusion path, and facilitates the extraction of carrot leaf oil by supercritical CO2 extraction. Furthermore, it gives the carrot leaf residue a porous channel, which can better adsorb seasonings or water during food preparation, thus increasing the application range of carrot leaf residue.

[0019] Liquid nitrogen is used for dispersion. After liquid nitrogen penetrates the porous structure, it increases the brittleness of the freeze-dried material, which facilitates rapid pulverization. This results in large-area cell pulverization. During the extraction process, the extraction medium flows around and contacts the further damaged cells, promoting the release of the encapsulated oil bodies and thus further improving the extraction rate of carrot leaf oil.

[0020] The porous structure formed by freeze drying increases the penetration depth of the extraction solvent. Combined with the ultra-fine particle size of liquid nitrogen pulverization, it can promote the extraction process, reduce extraction time, increase the yield of substances, and retain nutritional value.

[0021] Preferably, before supercritical CO2 extraction, the freeze-dried carrot leaf pulp in step S3 undergoes pretreatment. The specific steps are as follows: 90-95% ethanol is added to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.2-1.7, and 0.3-0.5% citric acid is added to the ethanol. The mixture is then thoroughly mixed to complete the pretreatment.

[0022] By adopting the above technical solution, the effective substances such as terpenes, flavonoids, and polyphenols in carrot leaves are all easily soluble in ethanol. Using ethanol as an entrainer can enhance the dissolution of fat-soluble components such as terpenes and esters through intermolecular forces, overcoming the polarity limitations of the extraction process and improving the yield of fat-soluble components. The material-to-liquid ratio is limited; when the ratio is >1:2, excess ethanol easily leads to solute redissolution, while when the ratio is <1:1, insufficient entrainer significantly reduces the extraction rate. Simultaneously, low-pressure, high-efficiency extraction can be maintained, improving the extraction rate while shortening the extraction time. The ethanol concentration is limited to 90-95%, utilizing high-concentration ethanol. It exhibits better compatibility with CO2, and the residual amount of the extract can be controlled below 200 ppm after depressurization separation, meeting food standards (≤500 ppm) without nitrogen purging. At the same time, the residual amount in carrot leaf residue is ≤0.1%, also meeting food standards (≤500 ppm), and the low moisture content facilitates subsequent drying processes and largely avoids microbial growth. The recovery rate of 90-95% ethanol is high, and recycling can reduce production costs. Citric acid can block the oxidation chain reaction, reduce the photosensitive degradation of carotenoids, and increase the nutrient content in carrot leaf residue.

[0023] Preferably, the supercritical CO2 extraction in S3 is performed at an extraction temperature of 45-55℃, a pressure of 25-30MPa, a static impregnation time of 30-40min, a dynamic extraction time of 60-90min, and a CO2 flow rate of 15-20kg / h.

[0024] By adopting the above technical solution, after premixing 90-95% ethanol for 30-40 minutes of static impregnation, followed by dynamic extraction under increased pressure, it is possible to ensure that ethanol and CO2 are fully mixed, thus guaranteeing the enhancing effect of the entrainer on the extraction.

[0025] Preferably, in step S1, after washing the carrot leaves, enzyme-loaded dietary fiber is added at a rate of 1-3%, and then water is added for grinding and pulping. The enzyme-loaded dietary fiber is prepared from celery dietary fiber, sodium alginate solution, cellulase and ethyl cellulose coated pectinase in a mass ratio of 1:0.2-0.4:0.1-0.15:0.1-0.15.

[0026] By adopting the above technical solution, after washing carrot leaves, enzyme-loaded dietary fiber is sprayed onto the surface. During the grinding and pulping process, the celery dietary fiber, which is insoluble in water, utilizes the viscosity of sodium alginate solution to facilitate the adhesion of the enzyme-loaded dietary fiber to the carrot leaves. The celery dietary fiber has a certain hardness, which facilitates the destruction of cell walls during grinding. Combined with cellulase, the cell walls are further destroyed, causing the fibrous skeleton in the carrot leaves to disperse. The disintegration between adjacent cell walls creates microporous channels, which reduces the diffusion barrier in the subsequent supercritical CO2 extraction process, shortens the mass transfer path, and allows volatile oil to flow out from the oil gland cells, thereby improving the extraction rate of volatile oil from carrot leaves.

[0027] Celery dietary fiber loads cellulase and ethyl cellulose-coated pectinase during the grinding process. The good flexibility of ethyl cellulose in forming a film helps control the release of pectinase, as its release can easily separate oil sacs or secretory cells from the tissue. This minimizes the release of large amounts of volatile oil during grinding, thus reducing the yield. The grinding process primarily utilizes the disruption of carrot leaf cell walls by celery dietary fiber and cellulase to ensure smooth flow and transfer of the extraction medium. Before extraction, contact with ethanol allows for the gradual release of pectinase due to the ethanol-soluble nature of ethyl cellulose. Pectinase decomposes pectin, the main component of the intercellular layer, disrupting the adhesion structure of adjacent cells and promoting volatile oil release. This pre-extraction promotion, combined with supercritical CO2 extraction, further enhances the extraction rate of volatile oils.

[0028] After extraction, the pectinase and cellulase on the surface of celery dietary fiber remain in the carrot leaf residue. On the one hand, celery dietary fiber, carrying substances such as ethyl cellulose, can block chlorophyll, carotene, and other substances, improving the nutritional value of the carrot leaf residue. On the other hand, celery dietary fiber can promote digestion and is rich in dietary fiber, vitamins, and minerals, thus having the effects of promoting digestion, regulating blood sugar, and anti-oxidation. Furthermore, pectinase, cellulase, and ethyl cellulose can all be added to food without harming the human body. In carrot leaf residue, they combine with carotene and carrot fiber to be added to food products such as pasta, resulting in a better taste and higher nutritional value.

[0029] Preferably, after the freeze-dried carrot leaf pulp has been pretreated, 1-3% oat dietary fiber powder is added, mixed well, and then subjected to supercritical CO2 extraction.

[0030] By employing the above technical solutions, oat dietary fiber, sodium alginate, and celery dietary fiber can neutralize the residual acid after pretreatment, controlling the pH of the system before extraction, as chlorophyll is easily lost under acidic conditions. Combined with the porous adsorption effect of dietary fiber, it facilitates chlorophyll adsorption, minimizing the partial dissolution of chlorophyll by CO2 during supercritical CO2 extraction, resulting in a high chlorophyll content in the carrot leaf residue. Simultaneously, the carboxyl groups in celery fiber selectively bind to the phenolic hydroxyl groups of oat fiber, resulting in Cu. 2+ / Fe 3+ Metal ions, the core catalytic factor that blocks the magnesium removal reaction of chlorophyll, ensure the chlorophyll content in carrot leaf residue, thus giving the carrot leaf residue high nutritional value.

[0031] Secondly, this application provides a carrot leaf powder, which adopts the following technical solution: A carrot leaf powder is obtained by extracting carrot leaf oil from carrot leaf residue, which is then dried, pulverized, and sieved to obtain the carrot leaf powder.

[0032] By adopting the above technical solution, the prepared carrot leaf powder removes the volatile oils from carrot leaves, resulting in a fresher taste. It can be used to prepare instant beverages and noodle products.

[0033] Preferably, the drying is carried out at 50-60°C, and liquid nitrogen is used to assist in the pulverization process, with the pulverization temperature controlled at 10-20°C.

[0034] By adopting the above technical solution, carrot leaf residue is ultra-finely pulverized to produce carrot leaf powder. Because both freeze-drying and supercritical CO2 extraction processes are carried out at low temperatures, the nutrients in carrot leaves are largely preserved. Carrot leaf powder is rich in dietary fiber, various vitamins and minerals, especially vitamin A, vitamin K and calcium. Carrot leaf powder is a low-sugar, low-calorie, and high-nutrient health food. After removing volatile oils, the flavor of carrot leaf powder is significantly improved, with a fresh taste and significantly enhanced palatability.

[0035] Carrot leaf powder has a fine texture and no residue. The freeze-drying process makes it highly rehydrated, and its water-soluble pectin content gives it a smooth texture. It can be used to prepare instant beverages with a refreshing taste and rich nutrition. It can also be used to prepare steamed buns, noodles, dumpling wrappers and other flour products to improve their nutritional value.

[0036] In summary, this application has the following beneficial effects: 1. Carrot leaves are ground and pulped at low temperature, then freeze-dried under vacuum and extracted with supercritical CO2 to obtain carrot leaf oil and carrot leaf residue. The carrot leaf residue is then ultra-finely pulverized and sieved to obtain carrot leaf powder. This technology simultaneously obtains carrot leaf oil containing bioactive substances but with poor flavor, as well as carrot leaf powder with undesirable flavor removed. No wastewater or waste is generated, and the various components of the carrot leaves' nutritional and active substances are largely preserved, thereby improving the utilization and consumption rate of carrot leaves and enhancing their high-value utilization.

[0037] 2. Carrot leaf residue is dried, pulverized, and sieved to obtain carrot powder. The powder is fine in texture, and the freeze-drying process makes it rehydrated well. Because it contains water-soluble pectin, it has a smooth texture and can be used to prepare instant beverages with a refreshing taste and rich nutrition. It can also be used to prepare steamed buns, noodles, dumpling wrappers, and other flour products, improving their nutritional value.

[0038] 3. Carrot leaves undergo a series of processes including pulping, pre-freezing, vacuum freeze-drying, pulverizing, freeze-drying, and supercritical CO2 extraction. Low-temperature grinding and pulping effectively breaks down the carrot leaf tissue, allowing for the full release of volatile substances during subsequent extraction and improving the extraction rate. The long ice crystals formed by slow pre-freezing can puncture some of the carrot leaf cells, further releasing cell sap and contributing to the improved extraction rate. The added citric acid chelates metal ions, preventing the carrot leaf pulp from oxidizing and deteriorating. Vacuum freeze-drying, compared to traditional hot air drying, effectively removes moisture while better preserving heat-sensitive and volatile substances. The porous structure formed by ice crystal sublimation also facilitates the dissolution and release of active ingredients during subsequent extraction, ensuring effective extraction while achieving dehydration, increasing oil yield, and retaining more nutrients. Detailed Implementation

[0039] The present application will be further described in detail below with reference to the embodiments.

[0040] Example of preparation of enzyme-loaded dietary fiber: In the following raw materials, pectinase and cellulase were purchased from Henan Ruilunte Biotechnology Co., Ltd., with 100,000 enzyme activities; ethyl cellulose was purchased from Guangdong Mingcheng Biotechnology Co., Ltd., which produced food-grade ethyl cellulose; other raw materials and equipment were commercially available.

[0041] Preparation Example 1: Enzyme-loaded dietary fiber was prepared using the following method: 50g of ethyl cellulose solution was uniformly sprayed onto the surface of 100g of pectinase. The ethyl cellulose solution was a 1% (w / w) ethyl cellulose ethanol solution with 99% (w / w) ethanol. The solution was then freeze-dried to obtain ethyl cellulose-coated pectinase for later use. The ethyl cellulose-coated pectinase was then passed through a 200-mesh sieve. 0.26 kg of sodium alginate solution was evenly sprayed onto the surface of 1 kg of celery dietary fiber. The celery dietary fiber was passed through a 200-mesh sieve. The sodium alginate solution was a 1% (w / w) aqueous solution of sodium alginate. Then, 0.12 kg of cellulase and 0.12 kg of ethyl cellulose-coated pectinase were added. The cellulase was passed through a 200-mesh sieve. The addition rate was 100 g / min. During the addition process, the celery dietary fiber was continuously stirred at a speed of 40 r / min. After being mixed evenly, the mixture was freeze-dried and dispersed through an 80-mesh sieve to obtain enzyme-loaded dietary fiber.

[0042] Preparation Example 2: The difference between this preparation example and Preparation Example 1 is that: 0.2 kg of sodium alginate solution was evenly sprayed onto the surface of 1 kg of celery dietary fiber. The celery dietary fiber was passed through a 200-mesh sieve. The sodium alginate solution was a 1% sodium alginate aqueous solution. Then, 0.1 kg of cellulase and 0.1 kg of ethyl cellulose-coated pectinase were added. The cellulase was passed through a 200-mesh sieve. The addition rate was 100 g / min. During the addition process, the celery dietary fiber was continuously stirred at a speed of 40 r / min. After being mixed evenly, the mixture was freeze-dried and dispersed through an 80-mesh sieve to obtain enzyme-loaded dietary fiber.

[0043] Preparation Example 3: The difference between this preparation example and Preparation Example 1 is that: 0.4 kg of sodium alginate solution was evenly sprayed onto the surface of 1 kg of celery dietary fiber. The celery dietary fiber was passed through a 200-mesh sieve. The sodium alginate solution was a 1% (w / w) aqueous solution of sodium alginate. Then, 0.15 kg of cellulase and 0.15 kg of ethyl cellulose-coated pectinase were added. The cellulase was passed through a 200-mesh sieve. The addition rate was 100 g / min. During the addition process, the celery dietary fiber was continuously stirred at a speed of 40 r / min. After being mixed evenly, the mixture was freeze-dried and dispersed through an 80-mesh sieve to obtain enzyme-loaded dietary fiber. Example

[0044] All of the following ingredients are commercially available.

[0045] Example 1: A method for extracting carrot leaf oil: S1. Select, clean, and wash the carrot leaves. Then add water to control the material-to-liquid ratio at 1:5, grind and pulp them. During the grinding and pulping process, add liquid nitrogen to control the temperature at 3℃ to obtain carrot leaf pulp. S2. Carrot leaf slurry was freeze-dried under vacuum conditions of 40 Pa, freeze-drying pressure of 40 Pa, freeze-drying time of 4 h, and shelf temperature of 9 °C. Then it was pulverized under liquid nitrogen conditions of 10 °C to obtain freeze-dried carrot leaf slurry. S3. The freeze-dried carrot leaf pulp was extracted by supercritical CO2 extraction at a temperature of 50℃ and a pressure of 28MPa. The extraction was carried out by static soaking for 35 minutes and dynamic extraction for 80 minutes, with a CO2 flow rate of 18kg / h, to extract carrot leaf oil and carrot leaf residue.

[0046] Example 2: The difference between this example and Example 1 is that: S3. Add 95% ethanol to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.5 (g / mL). Add 0.3% citric acid to the ethanol and mix well to complete the pretreatment. Then, perform supercritical CO2 extraction. The extraction temperature of supercritical CO2 extraction is 45℃, the pressure is 30MPa, the static soaking is 35min, the dynamic extraction is 65min, and the CO2 flow rate is 20kg / h to extract carrot leaf oil and carrot leaf residue.

[0047] Example 3: The difference between this example and Example 1 is that: S3. Add 90% ethanol to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.7 (g / mL). Add 0.3% citric acid to the ethanol and mix well to complete the pretreatment. Then, perform supercritical CO2 extraction. The supercritical CO2 extraction temperature is 50℃, the pressure is 30MPa, the static soaking time is 30min, the dynamic extraction time is 60min, and the CO2 flow rate is 15kg / h to extract carrot leaf oil and carrot leaf residue.

[0048] Example 4: The difference between this example and Example 1 is that: S1. Select and clean the carrot leaves, add the enzyme-loaded dietary fiber prepared in Example 1 at a rate of 2% of the total amount of carrot leaves, then add water to control the material-liquid ratio at 1:5 and grind and pulp. During the grinding and pulping process, add liquid nitrogen to control the temperature at 3°C ​​to obtain carrot leaf pulp. S2. Add 0.6% citric acid to carrot leaf slurry, freeze at -10℃ without wind for 10h to obtain pre-frozen material, and freeze-dry under vacuum conditions of 40Pa, freeze-drying pressure of 40Pa, freeze-drying time of 4h, and shelf temperature of 9℃. Then, pulverize at low temperature under liquid nitrogen conditions of 10℃ to obtain freeze-dried carrot leaf slurry. S3. Add 92% ethanol (by mass) to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.5. Add citric acid (0.4% of the total ethanol content) to the ethanol and mix well to complete the pretreatment and obtain a premix. Add 2% of oat dietary fiber powder to the premix and mix well. Then, perform supercritical CO2 extraction at a temperature of 50℃ and a pressure of 28MPa. Static impregnation for 35 minutes and dynamic extraction for 80 minutes are performed at a CO2 flow rate of 18kg / h to extract carrot leaf oil and carrot leaf residue.

[0049] Example 5: The difference between this example and Example 4 is that: S1. Select and clean the carrot leaves, add the enzyme-loaded dietary fiber prepared in Example 2 at a rate of 1% of the total amount of carrot leaves, then add water to control the material-liquid ratio at 1:5 and grind and pulp. During the grinding and pulping process, add liquid nitrogen to control the temperature at 2°C to obtain carrot leaf pulp. S2. Add 0.5% citric acid to carrot leaf slurry and freeze it at -10℃ without wind for 12 hours to obtain pre-frozen material. Vacuum freeze-drying is carried out under the conditions of vacuum degree 30Pa, freeze-drying pressure 30Pa, freeze-drying time 5 hours and shelf temperature 8℃. Then, the material is pulverized at low temperature under liquid nitrogen conditions of 20℃ to obtain freeze-dried carrot leaf slurry. S3. Add 95% ethanol (by mass) to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.2. Add 0.3% citric acid to the ethanol and mix well to complete the pretreatment. After pretreatment, a premix is ​​obtained. Add 1% oat dietary fiber powder to the premix and mix well. Then, extract by supercritical CO2 at a temperature of 45℃ and a pressure of 30MPa. Static impregnation for 30min, dynamic extraction for 90min, and CO2 flow rate of 15kg / h are used to extract carrot leaf oil and carrot leaf residue.

[0050] Example 6: The difference between this example and Example 4 is that: S1. Select and clean the carrot leaves, add the enzyme-loaded dietary fiber prepared in Example 3 at a rate of 3% of the total amount of carrot leaves, then add water to control the material-liquid ratio at 1:5 and grind and pulp the mixture. Add liquid nitrogen to control the temperature at 4°C to obtain carrot leaf pulp. S2. Add 0.7% citric acid to carrot leaf slurry and freeze it at -12℃ without wind for 8 hours to obtain pre-frozen material. Freeze-dry it under vacuum of 50 Pa, freeze-drying pressure of 50 Pa, freeze-drying time of 3 hours, and vacuum freeze-dry it under shelf temperature of 10℃. Then, pulverize it at low temperature under liquid nitrogen at 4℃ to obtain freeze-dried carrot leaf slurry. S3. Add 90% ethanol (by mass) to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.7. Add 0.5% citric acid to the ethanol and mix well to complete the pretreatment. After pretreatment, a premix is ​​obtained. Add 3% oat dietary fiber powder to the premix and mix well. Then, perform supercritical CO2 extraction. The supercritical CO2 extraction temperature is 55℃, the pressure is 25MPa, the static impregnation is 40min, the dynamic extraction is 60min, and the CO2 flow rate is 20kg / h to extract carrot leaf oil and carrot leaf residue.

[0051] Example 7: The difference between this example and Example 4 is that: In the preparation of enzyme-loaded dietary fiber, celery dietary fiber was replaced with an equal mass of water-soluble citrus dietary fiber.

[0052] Example 8: The difference between this example and Example 4 is that: In the preparation of enzyme-loaded dietary fiber, the ethyl cellulose solution is replaced with an equal mass of sodium alginate solution, i.e., sodium alginate-coated pectinase, and the sodium alginate solution is a 1% sodium alginate aqueous solution.

[0053] Example 9: A carrot leaf powder: The carrot leaf residue obtained by any of the methods in Examples 1-8 was dried at 50°C, then ultra-finely pulverized, with liquid nitrogen assisted in the pulverization process, the pulverization temperature was controlled at 10°C, and the residue was sieved through a 300-mesh sieve to obtain carrot leaf powder.

[0054] Application examples Application Example 1: Application of Carrot Leaf Oil: Take 2 ml of carrot leaf oil prepared in Example 2, 100 g of beef, 20 g of butter, 20 g of 4°C ice water, and 1.9 g of salt. After mixing at high speed until the mixture becomes elastic, add 15 g of 4°C ice water and 10 g of potato starch. Mix at low speed until evenly mixed, shape into balls, keep warm at 80°C for 10 minutes, cool, and quick-freeze at -18°C to obtain beef balls.

[0055] Application Example 2: The difference between this application example and Application Example 1 is that: Take 2 ml of the carrot leaf oil prepared in Example 2 and spray it evenly on the surface of a 2×2×1cm salmon piece. Store at 4°C.

[0056] Application Example 3: The difference between this application example and Application Example 1 is that: Take 1 ml of carrot leaf oil and 100 ml of flaxseed oil prepared in Example 2, mix them evenly, and fill them into a container.

[0057] Application Example 4: The difference between this application example and Application Example 1 is that: Take 10g of carrot leaf powder prepared in Example 1, 90g of flour, and 1g of salt. Mix them evenly, add 50g of room temperature water, stir into a dough, knead and roll until the dough is moist and formed, roll to 0.8mm, cut into strips of 3.0mm, dry at 40℃ for 60 minutes, and dry at 50℃ for 90 minutes. Vacuum package and store away from light.

[0058] Application Example 5: The difference between this application example and Application Example 4 is that: Carrot leaf powder prepared using Example 2.

[0059] Application Example 6: The difference between this application example and Application Example 4 is that: Carrot leaf powder prepared using Example 3.

[0060] Performance testing 1. Detection of the extraction rate of carrot leaf oil Carrot leaf oil was prepared using the methods described in Examples 1-8. Using the same mass of raw materials, the extraction rate of carrot leaf oil was calculated as the ratio of the final obtained carrot leaf oil to carrot leaves × 100%, and the data were recorded.

[0061] 2. Detection of chlorophyll retention rate in carrot leaf residue Carrot leaf residue was obtained using the methods described in Examples 1-7, and the chlorophyll content in the carrot leaf residue was calculated as 100% of the chlorophyll content in the carrot leaves. The data were recorded.

[0062] Table 1 Performance Test Table (In the table, "-" indicates that the corresponding embodiment did not test this item, so there is no data) project Extraction rate / % Retention rate / % Example 1 0.26 86.2 Example 2 0.31 90.6 Example 3 0.29 88.7 Example 4 0.38 93.5 Example 5 0.37 93.3 Example 6 0.39 93.6 Example 7 0.34 91.8 Example 8 0.36 - As can be seen from Examples 1-3 and Table 1, the method used in this application has a high extraction rate of carrot leaf oil and a high lutein retention rate, which gives carrot leaf powder better nutritional value, improves the utilization and consumption rate of carrot leaves, and enhances the high-value utilization of carrot leaves.

[0063] Combining Examples 1 and 4-6 with Table 1, it can be seen that adding enzyme-loaded dietary fiber to carrot leaves after washing, and adding oat dietary fiber before extraction, improves the extraction rate of carrot leaf oil and also increases the retention of carotene in carrot leaf residue.

[0064] Combining Examples 4 and 7-8 with Table 1, it can be seen that in the preparation of enzyme-loaded dietary fiber in Example 7, when water-soluble citrus dietary fiber was replaced with the same mass of celery dietary fiber, the extraction rate and retention rate of Example 7 were lower than those of Example 4. This indicates that water-soluble citrus dietary fiber is acidic and water-soluble, while celery dietary fiber is alkaline and water-insoluble. The presence of acidity easily affects the chlorophyll retention rate, and excessively water-soluble and softened dietary fiber is not easy to break down cell walls, affecting the extraction rate. The carboxyl groups in celery fiber selectively bind metal ions with the phenolic hydroxyl groups in oat fiber, blocking the core catalytic factor of chlorophyll demagnesiation reaction and ensuring the chlorophyll in carrot leaf residue.

[0065] In Example 8, during the preparation of enzyme-loaded dietary fiber, the ethyl cellulose solution was replaced with an equal mass of sodium alginate solution, i.e., sodium alginate-coated pectinase. The sodium alginate solution was a 1% sodium alginate aqueous solution. Compared with Example 4, the extraction rate and retention rate of Example 8 were lower than those of Example 4. This indicates that the sodium alginate solution is water-soluble and easily causes the pectinase to be released prematurely, leading to the easy volatilization of volatile oils.

[0066] 3. Antioxidant properties test of carrot leaf oil Carrot leaf oil was obtained using the methods of Examples 1-3, and the antioxidant capacity of the three examples was tested using the DPPH method. The test results are recorded in Table 2.

[0067] Table 2 Antioxidant Detection Table project Clearance rate / % Example 1 44.75％ Example 2 52.21％ Example 3 47.38％ 4. Antibacterial activity test of carrot leaf oil Carrot leaf oil was obtained using the methods described in Examples 1-3, and the minimum inhibitory concentration (MIC) was determined by the broth dilution method. The test results are recorded in Table 3.

[0068] Table 3 Antioxidant Test Table 5. Application Testing of Carrot Leaf Oil Taking Application Example 1, a blank control group was simultaneously prepared. The difference between the two groups was that no carrot leaf oil was added. Both groups were placed in the refrigerator for 15 days in an unpackaged state. The TBARS values ​​of the two groups were measured, and the sensory and taste characteristics of the beef balls were observed. The TBARS value of the blank group was 1.5 mg MDA / kg, and the TBARS value of the application group was 0.9 mg MDA / kg. It can be seen that the TBARS value of the application group was 40% lower than that of the blank group, indicating that carrot leaf oil can effectively inhibit lipid oxidation products. In terms of color, the blank group was grayish-white, while the application group had a brighter color, indicating that carrot leaf oil can effectively delay browning.

[0069] Taking Application Example 2, a blank control group was simultaneously prepared. The difference between the blank control group and Application Example 2 was that no carrot leaf oil was added. Both groups were stored at 4°C for 3 days in their unpackaged state, and the total bacterial count was measured. The total bacterial count in the blank control group was 2.1 × 10⁻⁶. 5 CFU / g, the total bacterial count in the application group was 1.2 × 10⁻⁶. 3 CFU / g. It is evident that the total bacterial count in the applied group was significantly lower than that in the control group, indicating that carrot leaf oil has a significant antibacterial effect.

[0070] Taking Application Example 3, a blank control group was simultaneously prepared. The difference between the two groups was that no carrot leaf oil was added. Both groups were placed in an incubator at 28°C for 48 hours in their unpackaged state, and the peroxide value was measured. The peroxide value of the blank group was 0.65 g / 100 g, while that of the application group was 0.12 g / 100 g. This shows that the colony peroxide value of the application group was 81% lower than that of the blank group, indicating that carrot leaf oil has a significant antioxidant effect.

[0071] 6. Detection of Carrot Leaf Powder Application For Application Examples 4-6, a blank control group was simultaneously prepared as Comparative Example 1. The difference between Comparative Example 1 and Application Examples 5-7 is that carrot leaf powder was not added. Meanwhile, the freeze-dried carrot leaf pulp from step S2 was taken as Comparative Example 2. The difference between Comparative Example 2 and Application Examples 4-6 is that carrot leaf oil was not extracted. Sensory evaluation: Weigh 100g of the prepared noodles from each group and place them in a steamer containing 1000mL of boiling water. Cook on an induction cooker at 1600W for 6 minutes. Immediately remove the noodles and place them in 500mL of 0℃ ice water for about 30 seconds. Then remove the noodles and place them in a sample dish containing ice for sensory evaluation. Refer to the noodle quality evaluation standard formulated in GB / T 35875-2018 "Grain and Oil Inspection: Evaluation of Processed Wheat Flour Noodles" and combine it with the actual situation to formulate evaluation standards, as shown in Table 3. A panel of 10 graduate students with relevant professional knowledge was formed. The panel members were trained and given sensory evaluation forms. They were asked to score the noodles prepared in Examples 4-6 and Comparative Examples 1-2. The specific evaluation results are shown in Table 4.

[0072] Table 4 Sensory Detection Indicators Table 5 Sensory evaluation results project Solidity elasticity Smoothness Taste Surface condition Color Total Score Application Example 4 7 17 17 19 7 7 74 Application Example 5 7 18 18 21 8 7 79 Application Example 6 7 16 16 19 8 7 74 Comparative Example 1 6 15 14 18 5 6 64 Comparative Example 2 7 15 12 12 4 7 57 Combining Application Examples 4-6 and Comparative Examples 1-2 with Tables 4 and 5, it can be seen that noodles prepared after carrot leaves were extracted for cucurbit oil showed a significant improvement in taste scores, indicating that the flavor acceptance of carrot leaves without cucurbit oil was significantly enhanced. The noodles in Application Examples 5-7 showed a slight improvement in elasticity because carrot leaves contain a small amount of pectin, which improves the texture of the noodles.

[0073] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for extracting carrot leaf oil, characterized in that, Includes the following steps: S1. After sorting, selecting, washing, grinding and pulping the carrot leaves, carrot leaf pulp is obtained. S2. The carrot leaf slurry is vacuum freeze-dried and pulverized to obtain freeze-dried carrot leaf slurry; S3. The freeze-dried carrot leaf pulp was extracted with supercritical CO2 to obtain carrot leaf oil, yielding carrot leaf residue.

2. The method for extracting carrot leaf oil according to claim 1, characterized in that: During the grinding and pulping process in S1, liquid nitrogen is added to control the temperature at 2-4℃.

3. The method for extracting carrot leaf oil according to claim 1, characterized in that, The carrot leaf slurry in S2 undergoes pretreatment before vacuum freeze-drying. The specific pretreatment steps are as follows: 0.5-0.7% citric acid is added to the carrot leaf slurry, and it is statically frozen at a temperature of -12℃ to -10℃ for 8-12 hours to obtain pre-frozen material, thus completing the pretreatment.

4. The method for extracting carrot leaf oil according to claim 3, characterized in that, The specific steps of vacuum freeze-drying of carrot leaf slurry in S2 are as follows: the pre-frozen material is freeze-dried under the conditions of freeze-drying pressure of 30-50Pa, freeze-drying time of 3-5h, and shelf temperature of 8-10℃.

5. The method for extracting carrot leaf oil according to claim 1, characterized in that, Before supercritical CO2 extraction, the freeze-dried carrot leaf pulp in S3 undergoes pretreatment. The specific steps are as follows: 90-95% ethanol is added to the freeze-dried carrot leaf pulp at a material-to-liquid ratio of 1:1.2-1.

7. Citric acid with a content of 0.3-0.5% is added to the ethanol, and the mixture is stirred evenly to complete the pretreatment.

6. The method for extracting carrot leaf oil according to claim 1, characterized in that, The supercritical CO2 extraction in S3 is performed at an extraction temperature of 45-55℃, a pressure of 25-30MPa, a static impregnation time of 30-40min, a dynamic extraction time of 60-90min, and a CO2 flow rate of 15-20kg / h.

7. The method for extracting carrot leaf oil according to claim 1, characterized in that, In step S1, after washing the carrot leaves, enzyme-loaded dietary fiber is added at a rate of 1-3%, and then water is added for grinding and pulping. The enzyme-loaded dietary fiber is prepared from celery dietary fiber, sodium alginate solution, cellulase and ethyl cellulose coated pectinase in a mass ratio of 1:0.2-0.4:0.1-0.15:0.1-0.

15.

8. The method for extracting carrot leaf oil according to claim 5, characterized in that, After the freeze-dried carrot leaf pulp is pretreated, 1-3% oat dietary fiber powder is added, mixed well, and then subjected to supercritical CO2 extraction.

9. A carrot leaf powder, characterized in that, The carrot leaf residue obtained by the extraction method of carrot leaf oil according to any one of claims 1-8 is dried, pulverized and sieved to obtain carrot leaf powder.

10. A carrot leaf powder according to claim 9, characterized in that, The drying process is carried out at 50-60℃, and liquid nitrogen is used to assist in the pulverization process, with the pulverization temperature controlled at 10-20℃.

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