Ultrahigh pressure assisted extraction process of peony rhizome essential oil

Abstract

The invention discloses an ultrahigh pressure assisted extraction technology of peony rhizome essential oil, and relates to the technical field of peony rhizome essential oil extraction.The technology comprises the steps that S1, raw material pretreatment is conducted, specifically, dried peony rhizomes free of mildew, worm damage and damage are selected, surface soil, deadwood and fibrous root impurities are removed, deionized water is used for washing until the surfaces are free of stains, and the peony rhizome essential oil is obtained; drying in a constant-temperature drying oven until the mass is basically constant; through the process of combining liquid nitrogen spraying quick-freezing and gradient crushing, essential oil volatilization loss caused by normal-temperature crushing is avoided, the problem that after quick-freezing, direct fine crushing is prone to caking is solved, meanwhile, cell walls and fiber structures of peony rhizomes are effectively damaged, obstacles are cleared away for subsequent solvent permeation, and the quality of the peony rhizomes is improved. Through a double-solvent gradient permeation process of low-concentration ethanol preliminary infiltration impurity removal and composite solvent ultrahigh-pressure coupling extraction, the extraction selectivity is improved, efficient separation of essential oil and polar impurities is realized, and the extraction efficiency and purity of the essential oil are further improved.

Description

Technical Field

[0001] This invention relates to the field of peony rhizome essential oil extraction technology, specifically to an ultra-high pressure assisted extraction process for peony rhizome essential oil. Background Technology

[0002] Peony, a perennial woody plant belonging to the genus Paeonia in the family Paeoniaceae, has rhizomes that serve as the core nutrient storage organs of the plant. These rhizomes not only transport and store nutrients but also accumulate a variety of high-value bioactive components, including essential oils, paeoniflorin, paeonol, and flavonoids, making them an important source of natural active substances. Peony rhizome essential oil is a volatile aromatic mixture extracted from peony rhizomes, containing compounds such as terpenes and phenols. It exhibits significant anti-inflammatory, antioxidant, and antibacterial physiological activities, making it important for applications in multiple fields. In the daily chemical industry, it can be used as a natural fragrance to replace chemically synthesized fragrances in cosmetics and perfumes. In the pharmaceutical field, it has key application potential, especially in the manufacture of chemical pharmaceutical raw materials and formulations. Its natural active components can synergistically work with chemical raw materials to enhance the core efficacy of drugs, such as anti-inflammatory and antibacterial effects, while reducing the dosage of chemical drugs to minimize side effects. Furthermore, the antioxidant properties of the essential oil can act as a formulation stabilizer, delaying the oxidative degradation of chemical raw materials and ensuring the shelf life and quality stability of formulations, aligning with the modern pharmaceutical development direction of natural synergy and green safety.

[0003] However, existing technologies for extracting peony rhizome essential oil still face certain technical bottlenecks. Peony rhizomes are hard, and the essential oil is encased in thick-walled tissues. Existing pulverization methods either result in essential oil volatilization and loss, or tissue adhesion, due to room temperature processing, or clumping caused by direct fine pulverization after quick-freezing, both of which affect subsequent extraction efficiency. Current extraction methods often use a single solvent, resulting in poor selectivity and difficulty in separating essential oil from polar impurities, leading to low essential oil purity. However, the purity requirements for raw materials in the manufacture of chemical pharmaceutical raw materials and formulations are stringent. Impurities can interfere with the purity testing of raw materials, damage the stability of formulations, and even pose risks to medication safety. At the same time, existing processes do not sufficiently destroy the fiber structure of the rhizome, resulting in insufficient dissolution of essential oil, low extraction efficiency, and poor raw material utilization. Therefore, developing an ultra-high pressure assisted extraction process for peony rhizome essential oil is of great significance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an ultra-high pressure assisted extraction process for peony rhizome essential oil. This process combines liquid nitrogen spraying and quick-freezing with gradient pulverization to avoid essential oil volatilization losses caused by room temperature pulverization. Simultaneously, it effectively destroys the cell walls and fiber structure of peony rhizomes. Through a dual-solvent gradient permeation process—preliminary impurity removal with low-concentration ethanol followed by ultra-high pressure extraction with a composite solvent—the extraction selectivity is improved, achieving efficient separation of essential oil from polar impurities. This increases the extraction efficiency and purity of the essential oil, ensuring that the purity of the extracted peony rhizome essential oil meets the requirements for chemical pharmaceutical raw materials and formulation manufacturing, guaranteeing the quality stability of the formulation, and fully leveraging its synergistic effect with chemical drugs to reduce drug side effects.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-pressure assisted extraction process for peony rhizome essential oil, the process comprising the following steps: S1. Raw material pretreatment: Select dried peony rhizomes that are free from mold, insects, and damage, remove surface soil, dead branches and fibrous roots, rinse with deionized water until the surface is free of stains, and dry in a constant temperature oven until the quality is basically constant. S2, Liquid nitrogen spray quick-freezing-gradient crushing: The pretreated peony rhizomes are sent into a continuous liquid nitrogen quick-freezing device, and liquid nitrogen is sprayed evenly and continuously onto the surface of the rhizomes. Then the quick-frozen rhizomes are transferred to a jaw crusher for crushing, and the crushed coarse particles are sent to an ultra-fine pulverizer for crushing to obtain peony rhizome pretreated powder. S3, Dual Solvent Gradient Permeation: Transfer the pretreated peony root powder to a sealed extraction tank, add ethanol solution, stir and soak at room temperature, then add composite extraction solvent to the extraction tank, stir evenly to allow the solvent to fully penetrate into the internal pores of the powder; S4. Ultra-high pressure coupling extraction: Transfer the mixture in the extraction tank into a high-temperature and high-pressure vacuum packaging bag, evacuate and seal it, and put the sealed vacuum packaging bag into the ultra-high pressure extraction equipment, set the pressure and maintain the pressure. S5. Subsequent purification treatment: The mixed system after ultra-high pressure extraction is taken out and filtered through a plate and frame filter press to remove solid residues. The filtrate is transferred to a separatory funnel and allowed to stand for separation. The upper organic phase is collected and sent to a rotary evaporator for vacuum distillation to remove the solvent and obtain crude essential oil. Finally, the crude essential oil is purified by silica gel column chromatography, and the target fraction is collected to obtain high-purity peony rhizome essential oil.

[0006] Furthermore, in step S1, the temperature of the constant temperature oven is set to 60℃. During the drying process, the peony rhizomes are weighed every 30 minutes, and the mass data of each weighing is recorded. When the mass difference between two consecutive weighings does not exceed 0.1g, the drying operation is stopped. At this time, it is determined that the peony rhizomes have reached a constant weight state. The peony rhizomes after constant weight are placed in a desiccator to cool to room temperature before being transferred to the subsequent processing stage.

[0007] Furthermore, in step S2, the mass ratio of liquid nitrogen to peony rhizomes is 1:6-1:8. Before spraying liquid nitrogen, check the unobstructed flow of the nozzles of the continuous liquid nitrogen quick-freezing device. After confirming that there is no blockage, start the spraying program and control the spraying time to 15-20 seconds. After spraying, let it stand for 2 minutes, and then transfer the quick-frozen rhizomes into a jaw crusher. Adjust the crusher gap to crush the rhizomes into coarse particles of 2-3 cm. After screening the coarse particles, remove particles with a diameter greater than 3 cm. Send the coarse particles that meet the requirements into an ultrafine pulverizer. Adjust the pulverizer parameters to make the powder particle size reach 80-100 mesh. Collect the pulverized peony rhizome pre-treatment powder and seal it for storage.

[0008] Furthermore, in step S3, the volume fraction of the ethanol solution added is 10%, and the ratio of the peony root pretreatment powder to the ethanol solution is 1:8. After the ethanol solution is slowly added to the sealed extraction tank, the stirring device is started, and the mixture is continuously stirred and soaked at room temperature for 30 minutes. After soaking, a composite extraction solvent is prepared according to the volume ratio of ethanol, ethyl acetate and water of 5:3:2. The composite extraction solvent is added to the extraction tank in three portions, and stirred for 5 minutes after each addition until the solvent and powder are evenly mixed.

[0009] Furthermore, in step S4, before transferring the mixing system in the extraction tank into the high-temperature and high-pressure vacuum packaging bag, the packaging bag is first tested for air tightness. The packaging bag is inflated to 0.1 MPa and left to stand for 10 minutes. After confirming that there is no leakage, the gas is discharged and then the mixing system is transferred in. The amount of the mixing system in the bag does not exceed 2 / 3 of the volume of the packaging bag. Then the packaging bag is connected to the vacuum equipment and vacuumed until the pressure inside the bag is ≤-0.09 MPa. After closing the vacuum valve, the opening of the packaging bag is heat-sealed. The sealed packaging bag is placed into the pressurization chamber of the ultra-high pressure extraction equipment, and the pressure transmission medium is injected into the pressurization chamber. The pressure is set to 300-450 MPa. After the set pressure is reached, the timing starts. The pressure holding time is 5-8 minutes. The pressure value of the equipment is recorded in real time during the pressure holding process.

[0010] Furthermore, in step S5, the filter cloth of the plate and frame filter press is selected as 120-mesh cotton filter cloth. During filtration, the vacuum degree is controlled at 0.06-0.07MPa. After the filter residue is collected, it is pressed a second time. The pressed juice is combined with the filtrate. The filtrate is transferred to a separating funnel, covered and allowed to stand for 20 minutes to separate into layers. After the separation is completed, the lower aqueous phase is released first, and then the upper organic phase is collected. The organic phase is transferred to the evaporation flask of the rotary evaporator. The evaporation temperature is set to 45℃ and the distillation pressure is 0.08MPa. The rotary evaporator is started. After the solvent is basically evaporated, the operation is stopped and the crude oil in the evaporation flask is collected.

[0011] Furthermore, before silica gel column chromatography purification in step S5, the silica gel particles are activated at 110°C for 2 hours. After cooling, the column is packed with silica gel and crude essential oil at a mass ratio of 10:1. During packing, the column is continuously tapped to avoid generating air bubbles. The eluent used in silica gel column chromatography purification in step S5 is a mixture of petroleum ether and ethyl acetate, with a volume ratio of 8:2. Before elution, the silica gel column is pre-washed with 5 column volumes of eluent. The eluent is collected and its purity is tested. Pre-washing is stopped when the eluent is clear and free of impurities. The crude essential oil is then dissolved with a small amount of eluent and loaded onto the column at a loading rate of 1 drop / second. Elution is then performed at the same rate, and the eluted fractions are collected in segments.

[0012] Furthermore, in step S2, the continuous liquid nitrogen quick-freezing device has four nozzles, which are evenly distributed around the inside of the device. The included angle between adjacent nozzles is 90°. The liquid nitrogen spraying rate of each nozzle is set to 20-30 mL / s. During the spraying process, the peony roots and stems move slowly at a speed of 5 cm / s via a conveyor belt. The surface of the conveyor belt is covered with an anti-slip pad to prevent the roots and stems from sliding or shifting during the movement.

[0013] Furthermore, in step S3, the stirring rate of the sealed extraction tank is set to 150-200 rpm. The stirring device is a spiral stirring paddle with a diameter of 1 / 3 of the inner diameter of the extraction tank. The depth of the stirring paddle into the powder and solvent mixture in the extraction tank is 2 / 3 of the height of the mixture in the tank. During the stirring process, the mixing status is observed every 10 minutes. When powder agglomeration is found, the stirring rate is appropriately increased by 10 rpm. After stirring for 2 minutes, the initial rate is restored until the soaking and solvent mixing process is completed.

[0014] Compared with existing technologies, the ultra-high pressure assisted extraction process for peony rhizome essential oil has the following beneficial effects: This invention utilizes a process combining liquid nitrogen spray freezing and gradient pulverization to avoid essential oil volatilization losses caused by room temperature pulverization and to solve the problem of clumping when directly finely pulverized after freezing. Simultaneously, it effectively disrupts the cell walls and fiber structure of peony rhizomes, clearing obstacles for subsequent solvent penetration. A dual-solvent gradient permeation process, employing initial impurity removal with low-concentration ethanol followed by ultra-high pressure coupling extraction with a composite solvent, enhances extraction selectivity and achieves efficient separation of essential oils from polar impurities. This improves the extraction efficiency and purity of the essential oil. The optimized process ensures that the purity of the extracted peony rhizome essential oil meets the requirements for chemical pharmaceutical raw materials and formulations, guaranteeing the quality stability of the formulations while also leveraging its synergistic effect with chemical drugs to reduce side effects and expanding the application scenarios of the essential oil.

[0015] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 A flowchart of an ultra-high pressure assisted extraction process for peony rhizome essential oil; Figure 2 This is a flowchart of an ultra-high pressure assisted extraction process for peony rhizome essential oil. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] This invention provides an ultra-high pressure assisted extraction process for peony rhizome essential oil, aiming to solve problems such as essential oil volatilization loss, clumping, low purity, and poor extraction efficiency in existing processes. It offers a complete and precise technical solution. (See also...) Figure 1 and Figure 2 The specific details are as follows: The process consists of five core steps: raw material pretreatment, liquid nitrogen spray quick-freezing-gradient pulverization, dual solvent gradient permeation, ultra-high pressure coupling extraction, and subsequent purification.

[0020] In the raw material pretreatment stage, dried peony rhizomes free from mold, insects, and damage should be selected. After removing surface impurities, they should be rinsed clean with deionized water and dried in a 60℃ constant temperature oven until the quality is basically constant. The criterion for judgment is that the difference between two consecutive weighings does not exceed 0.1g. After drying, they should be cooled to room temperature for later use.

[0021] In the liquid nitrogen spray quick-freezing-gradient pulverization step, the mass ratio of liquid nitrogen to peony rhizomes is 1:6-1:8. The liquid nitrogen is sprayed through four evenly distributed nozzles at a rate of 20-30 mL / s for 15-20 seconds. After standing for 2 minutes, the quick-frozen rhizomes are crushed into coarse particles of 2-3 cm, and then ultra-finely pulverized to 80-100 mesh. The pretreated powder is then sealed and stored.

[0022] In the dual-solvent gradient permeation stage, add a 10% volume fraction of ethanol solution at a material-to-liquid ratio of 1:8, stir and soak for 30 minutes at 150-200 rpm at room temperature, and then prepare a composite solvent of ethanol, ethyl acetate and water at a volume ratio of 5:3:2. Add the solvent in three portions and stir for 5 minutes each time to ensure full solvent permeation.

[0023] During ultra-high pressure coupling extraction, the mixed system is placed in a vacuum packaging bag that has been tested for airtightness, vacuumed to ≤-0.09MPa and then sealed. It is then placed in an ultra-high pressure device, and the pressure transmission medium is injected. The pressure is maintained at 300-450MPa for 5-8 minutes, and the pressure data is recorded in real time.

[0024] In subsequent purification, a 120-mesh cotton filter cloth was used for filtration under a vacuum of 0.06-0.07 MPa. The filter residue was pressed twice, and the filtrates were combined. After standing for 20 minutes, the organic phase was collected in layers and then distilled under reduced pressure at 45℃ and 0.08 MPa to obtain crude essential oil. The crude oil was then purified by a chromatography column packed with activated silica gel. A mixture of petroleum ether and ethyl acetate in a volume ratio of 8:2 was used as the eluent. After pre-washing, the sample was loaded and eluted at a rate of 1 drop / second. The fraction that met the standard was collected to obtain high-purity essential oil.

[0025] The entire process achieves efficient extraction and high-purity separation of essential oils through precise control of parameters at multiple stages, meeting stringent requirements for the purity of raw materials.

[0026] Example 1 This embodiment uses a liquid nitrogen to peony root mass ratio of 1:6 and an ultra-high pressure extraction pressure of 300 MPa. Through a standard ultra-high pressure assisted extraction process, it verifies the essential oil extraction effect under low liquid nitrogen dosage and lower extraction pressure. Simultaneously, it focuses on testing the destructive effects of liquid nitrogen spray quick-freezing and gradient pulverization on the root structure, providing a reference for process cost control and structural optimization. (See [link to relevant documentation]). Figure 1 and Figure 2 The complete technical solution is as follows: Raw material pretreatment: Select 500 grams of dried peony rhizomes free from mold, insect infestation, and damage. Remove surface dirt, withered branches, and small rootlets by manual screening. Rinse the rhizomes repeatedly with deionized water until no visible stains remain. Place the rinsed rhizomes in a constant-temperature oven set to 60℃ for drying. Weigh the rhizomes every 30 minutes during drying and record the weight. When the weight difference between two consecutive weighings is 0.08 grams, the rhizomes are considered to have reached a constant weight. Quickly transfer the constant-weight rhizomes to a desiccator and allow them to cool naturally to room temperature before use.

[0027] Liquid nitrogen spray quick-freezing - gradient crushing: Before starting the continuous liquid nitrogen quick-freezing device, check that all four nozzles are unobstructed and free of blockages before starting the device. Prepare liquid nitrogen at a ratio of 1:6 (approximately 83.3 grams) of liquid nitrogen to peony rhizomes. Set the spray rate of liquid nitrogen from each nozzle to 20 ml per second, and simultaneously adjust the conveyor belt speed to 5 cm per second, allowing the peony rhizomes to move slowly along the conveyor belt and receive uniform spraying for 15 seconds. After spraying, let the rhizomes stand in the device for 2 minutes to ensure the core temperature of the rhizomes drops below -18°C for complete quick-freezing. Then, transfer the quick-frozen rhizomes to a jaw crusher, adjusting the crusher gap to break the rhizomes into coarse particles with a diameter of 2 to 3 cm. Use a sieve to remove particles larger than 3 cm to ensure uniform particle size. Feed the qualified coarse particles into the ultrafine pulverizer, adjust the pulverizer speed and screen parameters to make the pulverized powder reach a particle size of 80 mesh, collect the pulverized peony root and stem pretreatment powder, and immediately put it into a sealed bag for storage to prevent the powder from absorbing moisture or the essential oil from evaporating prematurely.

[0028] Dual-solvent gradient permeation: All pretreated peony root powder was transferred to a sealed extraction vessel. A 10% ethanol solution (by volume) was added at a powder-to-ethanol-solution ratio of 1:8. The extraction vessel's stirring device was activated, and the stirring speed was set to 150 rpm. The mixture was continuously stirred and soaked at room temperature for 30 minutes to allow the ethanol solution to fully wet the powder and initially dissolve some polar impurities. After soaking, a composite extraction solvent was prepared at a volume ratio of ethanol, ethyl acetate, and water of 5:3:2. This composite extraction solvent was added to the extraction vessel in three portions, with stirring for 5 minutes after each addition to ensure uniform mixing and thorough penetration into the powder's internal pores.

[0029] Ultra-high pressure coupling extraction: Select a high-temperature and high-pressure resistant vacuum packaging bag. First, inflate the bag to 0.1 MPa and let it stand for 10 minutes. After observing that there is no bulging or leakage in the bag, release the gas to complete the airtightness test. Slowly transfer the mixture in the extraction tank into the vacuum packaging bag, controlling the filling amount to not exceed 2 / 3 of the bag's volume to avoid bag rupture during subsequent pressurization. Connect the packaging bag to the vacuum equipment, turn on the vacuum pump to evacuate the bag until the pressure inside the bag drops to -0.095 MPa. After closing the vacuum valve, use a heat sealer to seal the opening of the packaging bag. Place the sealed packaging bag into the pressurization chamber of the ultra-high pressure extraction equipment, inject food-grade pressure-transmitting medium into the pressurization chamber, set the equipment pressure to 300 MPa, and start the pressurization program. When the equipment pressure reaches the set value, start timing. The pressure holding time is 5 minutes. During the pressure holding process, record the equipment pressure value every 1 minute to ensure that the pressure does not fluctuate.

[0030] Subsequent purification treatment: After the ultra-high pressure treatment, the vacuum packaging bag is removed and opened, and the mixture is transferred to the feed tank of a plate and frame filter press. A 120-mesh cotton filter cloth is selected as the filter medium, and the vacuum degree of the filter press is adjusted to 0.06 MPa. The equipment is then started for suction filtration. After filtration, the filter residue is collected and placed into a pressing device for secondary pressing. The juice produced during the pressing process is combined with the filtrate to improve the raw material utilization rate.

[0031] Transfer the combined filtrates into a separatory funnel, cap it, and let it stand at room temperature for 20 minutes until the filtrates have completely separated into layers. First, slowly release the lower aqueous phase, then collect the upper organic phase. Transfer the organic phase into the evaporation flask of a rotary evaporator. Set the evaporation temperature to 45℃ and the distillation pressure to 0.08MPa. Start the rotary evaporator and stop the operation when no obvious solvent dripping is observed in the evaporation flask. Collect the crude essential oil in the evaporation flask. Activate the silica gel particles in an oven at 110℃ for 2 hours. After cooling, pack the chromatography column with a silica gel to crude essential oil mass ratio of 10:1. During packing, gently tap the column continuously to avoid generating air bubbles that could affect the separation effect.

[0032] The eluent was prepared according to a volume ratio of petroleum ether to ethyl acetate of 8:2. The silica gel column was pre-eluted with 5 column volumes of eluent, and the eluent was collected and its purity was visually assessed. Pre-elution was stopped when the eluent was clear, transparent, and free of impurities. The crude essential oil was dissolved in a small amount of eluent and slowly loaded at a rate of 1 drop per second. Elution was then performed at the same rate, and the eluent fractions were collected in test tubes. The fractions that met the purity standards were selected to obtain high-purity peony rhizome essential oil.

[0033] In summary, this embodiment successfully completed the extraction process of peony rhizome essential oil under conditions of low liquid nitrogen usage and low extraction pressure. The liquid nitrogen spray freezing caused cracks in the rhizome cell walls due to low-temperature contraction, and gradient pulverization further refined the rhizome to 80 mesh, effectively disrupting its fibrous structure and facilitating subsequent solvent penetration. The resulting essential oil purity met basic application requirements, and the process parameters were stable with no abnormalities during operation, demonstrating that this process remains feasible and practical under cost-control conditions.

[0034] Example 2 This embodiment uses intermediate parameters of liquid nitrogen to peony root mass ratio of 1:7 and ultra-high pressure extraction of 375 MPa. The stirring rate of the composite solvent was optimized to 175 rpm. The focus is on exploring the synergistic effect of liquid nitrogen spray freezing and gradient pulverization on essential oil dissolution. Simultaneously, the balance between essential oil extraction efficiency and purity under moderate process intensity is analyzed, providing data support for the routine application of the process. (See [link to relevant documentation]). Figure 1 and Figure 2 The complete technical solution is as follows: Raw material pretreatment: Select 500 grams of dried peony rhizomes of the same quality as in Example 1. After manual removal of impurities and rinsing with deionized water, place them in a 60°C constant temperature oven for drying. Weigh them every 30 minutes. When the difference between two consecutive weighings is 0.06 grams, stop drying and transfer the rhizomes to a desiccator to cool to room temperature for later use.

[0035] Liquid nitrogen spray quick-freezing - gradient pulverization: After checking the unobstructed flow of the spray nozzles in the continuous liquid nitrogen quick-freezing device, prepare liquid nitrogen at a ratio of 1:7 (approximately 71.4 grams) to peony rootstock mass. Set the spray rate to 25 ml / s and the conveyor belt speed to 5 cm / s, and spray the rootstock evenly for 20 seconds. After spraying, let it stand for 2 minutes to ensure complete quick-freezing of the rootstock.

[0036] The quick-frozen rhizomes were transferred to a jaw crusher, crushed into coarse particles of 2 to 3 cm, and screened to remove impurities. They were then fed into an ultrafine pulverizer and ground to 90 mesh. The pretreated powder was collected and sealed for storage. Microscopic observation revealed that the powder particles pulverized under these parameters had a looser structure and a higher cell wall breakage rate than in Example 1, which facilitated solvent penetration.

[0037] Dual-solvent gradient permeation: The pretreated powder was transferred to a sealed extraction vessel, and a 10% (v / v) ethanol solution was added at a material-to-liquid ratio of 1:8. The stirring speed was set to 175 rpm, and the mixture was stirred and soaked at room temperature for 30 minutes. The mixing status was observed every 10 minutes during this period, and no powder agglomeration was observed, indicating that the ethanol solution could quickly wet the powder. Subsequently, a composite extraction solvent was prepared at a volume ratio of ethanol, ethyl acetate, and water of 5:3:2, and added in three portions, stirring for 5 minutes each time. The solvent permeation effect was good, and a homogeneous suspension system was formed between the powder and the solvent.

[0038] Ultra-high pressure coupling extraction: After the vacuum packaging bag passes the airtightness test, it is placed into the mixing system, vacuumed to -0.092MPa, and then sealed. The packaging bag is placed in the pressurization chamber of the ultra-high pressure extraction equipment, the pressure transmission medium is injected, the pressure is set to 375MPa, and the pressure is maintained for 6 minutes. During the pressure maintenance process, the pressure is stable without fluctuation, and the equipment is operating well.

[0039] Subsequent purification: The mixture was filtered using a 120-mesh cotton filter cloth under a vacuum of 0.065 MPa. The filter residue was pressed twice, and the juice was added to the filtrate. The filtrate was transferred to a separatory funnel and allowed to stand for 20 minutes to separate into layers. The upper organic phase was collected and subjected to vacuum distillation at 45℃ and 0.08 MPa to obtain crude essential oil. The crude essential oil was purified by activated silica gel chromatography using an 8:2 mixture of petroleum ether and ethyl acetate as the eluent at a rate of 1 drop per second. The purity of the collected fraction met the standards, yielding high-purity essential oil.

[0040] In summary, this embodiment, through optimization of intermediate parameter combinations and stirring rates, further enhances the synergistic effect of liquid nitrogen spray freezing and gradient pulverization, resulting in more thorough cell wall disruption in the rhizomes and a significant increase in solvent penetration efficiency. While improving extraction efficiency, the purity of the essential oil is also further improved. The operation of each step is smooth, with no abnormal parameter fluctuations, indicating that this process, under normal application, can achieve a good balance between efficiency, purity, and cost with moderately intensive parameters, and has the potential for widespread adoption.

[0041] Example 3 This embodiment employs a high-parameter configuration of liquid nitrogen to peony root mass ratio of 1:8 and ultra-high pressure extraction of 450 MPa. Simultaneously, the stirring rate of the composite solvent is increased to 200 rpm. The focus is on verifying the extreme destructive effect of liquid nitrogen spray freezing and gradient pulverization on the root structure under these high parameters, maximizing the efficiency and purity of essential oil extraction. This fully demonstrates the innovation and efficiency of the process of this invention. (See also...) Figure 1 and Figure 2 The complete technical solution is as follows: Raw material pretreatment: Take 500 grams of dried peony rhizomes that are free from mold, insects, and damage. After removing impurities and rinsing with deionized water, place them in a 60℃ constant temperature oven to dry. Weigh them every 30 minutes. When the difference between two consecutive weighings is 0.05 grams, it is confirmed that constant weight has been reached. Transfer the rhizomes to a desiccator to cool to room temperature.

[0042] Liquid nitrogen spray freezing-gradient pulverization: Adjust the spray rate of the continuous liquid nitrogen freezing device to 30 ml / s. Prepare liquid nitrogen at a ratio of 1:8 (62.5 g of liquid nitrogen to peony rootstock by weight). Maintain a conveyor belt speed of 5 cm / s and spray the rootstock evenly for 18 seconds. After spraying, let stand for 2 minutes. Confirm that the core temperature of the rootstock has dropped to -22°C by temperature monitoring, achieving deep freezing.

[0043] The quick-frozen rhizomes were transferred to a jaw crusher to be crushed into coarse particles of 2 to 3 cm. After screening, they were sent to an ultrafine pulverizer to be pulverized to 100 mesh. Testing showed that at these parameters, the powder had high particle size uniformity, completely ruptured cell walls, and a loose fibrous structure, creating excellent conditions for essential oil extraction. This fully demonstrates the technical advantages of combining liquid nitrogen spray quick-freezing with gradient pulverization.

[0044] Dual-solvent gradient permeation: The pretreated powder was transferred to a sealed extraction vessel, and a 10% (v / v) ethanol solution was added at a material-to-liquid ratio of 1:8. The stirring speed was set to 200 rpm, and the mixture was stirred and soaked at room temperature for 30 minutes. During this period, slight powder agglomeration was observed. The stirring speed was immediately increased to 210 rpm and stirred for 2 minutes before being reduced back to 200 rpm to ensure thorough mixing of the powder and ethanol solution. Subsequently, a composite extraction solvent was prepared at a volume ratio of ethanol, ethyl acetate, and water of 5:3:2. This solvent was added in three portions, with stirring for 5 minutes each time. The solvent rapidly permeated into the internal pores of the powder, forming a homogeneous extraction system.

[0045] Ultra-high pressure coupling extraction: The airtightness of the vacuum packaging bag is tested, and the mixture is placed inside. After evacuating to -0.098 MPa, the opening is heat-sealed. The packaging bag is placed in the pressurization chamber of the ultra-high pressure extraction equipment, and the pressure-transmitting medium is injected. The pressure is set to 450 MPa, and the time is started after the pressure is reached. The pressure is maintained for 8 minutes. The pressure remains stable without fluctuation during the pressure holding process. The ultra-high pressure and the previous structural destruction work synergistically to further promote the dissolution of essential oils.

[0046] Subsequent purification: The mixture was filtered through a 120-mesh cotton filter cloth under vacuum at 0.07 MPa. The residue was pressed twice, and the juice was combined with the filtrate. The filtrate was transferred to a separatory funnel and allowed to stand for 20 minutes to separate into layers. The upper organic phase was collected and distilled under reduced pressure at 45℃ and 0.08 MPa to obtain crude essential oil. The crude essential oil was purified by activated silica gel chromatography column chromatography using an 8:2 mixture of petroleum ether and ethyl acetate as the eluent at a rate of 1 drop per second. The purity of the collected fraction was excellent, yielding high-purity peony rhizome essential oil.

[0047] In summary, this embodiment maximizes the synergistic effect of liquid nitrogen spray freezing and gradient pulverization through high-parameter configuration and dynamic adjustment of stirring state. The cell walls and fibrous structures of the roots and stems are thoroughly disrupted, providing maximum channels for essential oil dissolution. Combined with ultra-high pressure coupling extraction and dual-solvent gradient permeation, the dissolution efficiency and purity of the essential oil are significantly improved. The excellent synergy of each process step fully verifies the outstanding performance of the process in high-efficiency extraction scenarios, meeting the stringent purity requirements of applications such as pharmaceuticals and high-end daily chemicals, highlighting the innovation and practicality of the process.

[0048] Comparative Example The traditional solvent extraction process involves the following steps: Raw material pretreatment: 500 grams of dried peony rhizomes of the same quality as in the example were selected. After removing impurities and rinsing with deionized water, they were dried at a constant temperature of 60°C until the quality was basically constant. After cooling, they were directly pulverized using a regular pulverizer. The pulverization process was carried out at room temperature without liquid nitrogen quick-freezing. Finally, the powder was pulverized to 80 to 100 mesh. After pulverization, the powder showed slight agglomeration due to room temperature treatment, and some essential oils volatilized during the pulverization process.

[0049] Single solvent extraction: The pulverized powder was transferred to a conventional extraction tank, and a 95% ethanol solution was added at a material-to-liquid ratio of 1:10. The heating device of the extraction tank was turned on, and the temperature was raised to 80°C before reflux extraction. The extraction time was 2 hours, during which the stirring rate was maintained at 150 rpm. Due to the lack of liquid nitrogen spraying for quick freezing and gradient pulverization in the early stage, the cell walls of the rhizomes were not sufficiently broken down, making it difficult for the solvent to penetrate effectively, resulting in a low essential oil dissolution efficiency.

[0050] Purification: After extraction, the heating device was turned off, and the mixture was allowed to cool naturally to room temperature. It was then filtered at normal pressure using a 120-mesh filter cloth. The filtration process was slow and incomplete, and the filter residue was discarded directly (without a secondary pressing step), resulting in the waste of some residual essential oil. The filtered liquid was directly transferred to a rotary evaporator and the solvent was removed by vacuum distillation at 60℃ and 0.08MPa to obtain crude essential oil. This crude oil was not purified by silica gel column chromatography and was used directly as the final product, which contained a significant amount of polar impurities.

[0051]

[0052] As can be clearly seen from the comparison table above, Examples 1 to 3 all used liquid nitrogen spraying with different parameters to achieve complete or even deep freezing of peony rhizomes. Combined with gradient pulverization, this effectively avoided the loss of essential oils due to room temperature pulverization and solved the problem of clumping caused by direct fine pulverization after simple quick freezing. It also fully destroyed the cell walls and fiber structure of the rhizomes, clearing the way for subsequent solvent penetration and essential oil dissolution. In contrast, the comparative example used a traditional process without liquid nitrogen spraying and quick freezing, relying solely on ordinary room temperature pulverization. This not only caused some essential oils to evaporate prematurely during the pulverization stage, but also made it difficult for subsequent solvents to penetrate effectively due to insufficient destruction of the rhizome structure. At the same time, the examples combined dual-solvent gradient penetration, ultra-high pressure coupling extraction, and fine purification to further improve extraction selectivity and essential oil purity. The comparative example used a single high-concentration ethanol solvent, conventional reflux extraction, and a simplified purification process, which not only resulted in low extraction efficiency but also led to poor purity of the final product due to incomplete impurity separation.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for the extraction of Paeonia suffruticosa Andr. rootstock essential oil by ultra-high pressure assisted extraction, characterized in that, The process comprises the following steps: S1, raw material pretreatment: select dry peony rootstocks without mildew, insect damage, and damage, remove surface soil, dry branches and root impurities, rinse with deionized water until the surface is free of stains, place in a constant temperature oven and dry until the mass is constant; S2, liquid nitrogen spray quick freezing-grading crushing: send the pretreated peony rootstocks into a continuous liquid nitrogen quick freezing device, spray liquid nitrogen uniformly and continuously onto the surface of the rootstocks, then transfer the quick frozen rootstocks into a jaw crusher for crushing, then send the crushed coarse particles into a super micro pulverizer for crushing, to obtain peony rootstock pretreatment powder; S3, double solvent gradient penetration: transfer the peony rootstock pretreatment powder into a sealed extraction tank, add ethanol solution, stir and soak at room temperature, then add a composite extraction solvent to the extraction tank, stir evenly to make the solvent fully penetrate into the powder internal pores; S4, ultra-high pressure coupling extraction: transfer the mixed system in the extraction tank into a high-temperature and high-pressure vacuum packaging bag, seal after vacuumizing, place the sealed vacuum packaging bag into an ultra-high pressure extraction equipment, set the pressure and maintain the pressure; S5, subsequent purification treatment: take out the mixed system after ultra-high pressure extraction, remove solid residues by plate and frame filter machine, transfer the filtrate into a separatory funnel for static layering, collect the upper organic phase, send the organic phase into a rotary evaporator for reduced pressure distillation to remove the solvent to obtain crude essential oil, finally purify the crude essential oil by silica gel column chromatography, collect the target fraction to obtain high-purity peony rootstock essential oil.

2. The process of claim 1, wherein the process is characterized by, The temperature of the constant temperature oven in step S1 is set to 60℃, the peony rootstocks are weighed every 30 minutes during the drying process, the mass data of each weighing is recorded, when the mass difference of two consecutive weighings is not more than 0.1g, the drying operation is stopped, at this time it is determined that the peony rootstocks reach the constant weight state, the constant weight peony rootstocks are cooled to room temperature in a desiccator, and then transferred to the subsequent processing link.

3. The process of claim 1, wherein the process is characterized by, In step S2, the mass ratio of liquid nitrogen to peony rootstocks is 1:6-1:8, the spraying time is controlled for 15-20 seconds, after spraying, the quick frozen rootstocks are transferred into a jaw crusher, the gap of the crusher is adjusted to crush the rootstocks to 2-3cm coarse particles, the coarse particles are screened to remove particles larger than 3cm in diameter, the qualified coarse particles are sent into a super micro pulverizer, the pulverizer parameters are adjusted to make the powder particle size reach 80-100 mesh, and the crushed peony rootstock pretreatment powder is collected and sealed for storage.

4. The process of claim 1, wherein the process is characterized by, In step S3, the volume fraction of the added ethanol solution is 10%, the solid-liquid ratio of the peony rootstock pretreatment powder to the ethanol solution is 1:8, after slowly adding the ethanol solution into the sealed extraction tank, the stirring device is started, and the stirring is continued at room temperature for 30 minutes, after the soaking is completed, the composite extraction solvent is prepared according to the volume ratio of ethanol, ethyl acetate and water 5:3:2, the composite extraction solvent is added into the extraction tank in three times, and stirred for 5 minutes after each addition, until the solvent and the powder are uniformly mixed.

5. The process of claim 1, wherein the process is characterized by, In the step S4, the vacuum packaging bag is vacuumized to a pressure of ≤-0.09 MPa, and then the vacuum valve is closed and the opening of the packaging bag is heat sealed. The sealed packaging bag is placed in a pressurized cavity of an ultra-high pressure extraction device, and a pressure transmitting medium is injected into the pressurized cavity. The pressure is set to 300-450 MPa, and the pressure is maintained for 5-8 minutes. The pressure value of the device is recorded in real time during the pressure maintaining process.

6. The process of claim 1, wherein the process is characterized by, In the step S5, the filter cloth of the plate-and-frame filter is selected to be a cotton filter cloth with a mesh size of 120. The vacuum degree is controlled to be 0.06-0.07 MPa during the suction filtration. After the filter residue is collected, the juice is subjected to secondary squeezing. The juice after the squeezing is combined with the filtrate. The filtrate is transferred into a separatory funnel, and is left to stand after being covered for 20 minutes. After the separation is completed, the lower water phase is discharged first, and then the upper organic phase is collected. The organic phase is transferred into an evaporation flask of a rotary evaporator. The evaporation temperature is set to 45°C, and the distillation pressure is set to 0.08 MPa. The rotary evaporator is started, and the operation is stopped after the solvent is basically evaporated. The crude essential oil in the evaporation flask is collected.

7. The process as claimed in claim 1, wherein the process is characterized by, In the step S5, the eluent used for the silica gel column chromatography purification is a mixture of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 8:

2. Before the elution, the silica gel column is pre-washed with 5 times the column volume of the eluent. The washing liquid is collected and detected for purity. When the washing liquid is clear and free of impurities, the pre-washing is stopped. Then, the crude essential oil is dissolved in a small amount of the eluent and is loaded. The loading rate is controlled to be 1 drop / s. Then, the elution is performed at the same rate. The elution fractions are collected in stages.

8. The process of claim 1, wherein the process is characterized by, In the step S2, the number of nozzles of the continuous liquid nitrogen quick-freezing device is 4. The liquid nitrogen spraying rate of each nozzle is set to 20-30 mL / s. During the spraying process, the peony rootstocks are slowly moved at a rate of 5 cm / s by a conveying belt.

9. The process of claim 1, wherein the process is characterized by, In the step S3, the stirring rate of the closed extraction tank is set to 150-200 revolutions per minute. During the stirring process, the mixing state is observed every 10 minutes. When the powder agglomeration is found, the stirring rate is appropriately increased by 10 revolutions per minute. After the continuous stirring for 2 minutes, the initial rate is restored. This process is repeated until the soaking and solvent mixing process is completed.

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