Method for extracting pericarpium citri reticulatae essential oil by using supercritical CO2 fluid and preparation method thereof

Abstract

This invention discloses a dried tangerine peel essential oil, the active ingredients of which include the following components by weight: D-limonene 30.0-80.0%, γ-terpinene 5.0-15.0%, β-myrcene 0.5-8.0%, α-pinene 0.5-8.0%, and β-pinene 0.2-5.0%. Simultaneously, this invention discloses a method for preparing dried tangerine peel essential oil using supercritical CO2 fluid extraction, comprising: selecting dried tangerine peel raw material, removing impurities, drying at 50-60℃ to a moisture content of 8%-12%, pulverizing and sieving, and collecting 20-60 mesh dried tangerine peel powder for later use; loading the pretreated dried tangerine peel powder into an extraction vessel, and introducing CO2 for supercritical fluid extraction; sequentially passing the extracted CO2 fluid carrying essential oil through a primary separation vessel and a secondary separation vessel for depressurization and separation, collecting the dried tangerine peel essential oil product at the bottom of the secondary separation vessel; dehydrating and drying the obtained dried tangerine peel essential oil, and then filtering it through a microporous membrane to obtain refined dried tangerine peel essential oil. By optimizing parameters such as raw material particle size, extraction pressure, temperature, and time, this invention achieves an extraction rate of 2.5%–3.2% for tangerine peel essential oil.

Description

Technical Field

[0001] This invention belongs to the field of traditional Chinese medicine, specifically relating to a method for extracting tangerine peel essential oil using supercritical CO2 fluid and its preparation. Background Technology

[0002] Dried tangerine peel (Chenpi) is the dried, mature peel of the citrus fruit (Citrus reticulata) and its cultivated varieties, belonging to the Rutaceae family. It is a traditional Chinese medicine with the effects of regulating qi, strengthening the spleen, drying dampness, and resolving phlegm. Dried tangerine peel contains abundant volatile oils, mainly including terpenes such as limonene, γ-terpinene, and β-myrcene, which have various biological activities such as antibacterial, antioxidant, and insecticidal properties.

[0003] Currently, the main methods for extracting tangerine peel essential oil include steam distillation and organic solvent extraction. While steam distillation is simple to operate, it suffers from problems such as high extraction temperature, long extraction time, low essential oil yield, and easy destruction of heat-sensitive components. Organic solvent extraction, although highly efficient, can leave toxic solvent residues in the product, affecting the quality and safety of the essential oil.

[0004] Supercritical CO2 extraction is a novel separation technology developed in recent years, offering advantages such as low extraction temperature, no solvent residue, good selectivity, and high extraction efficiency. Existing research has reported on supercritical CO2 extraction of volatile oils from dried tangerine peel, including the use of orthogonal experiments to optimize the extraction process. However, current methods suffer from drawbacks such as high extraction pressure (around 20 MPa), high energy consumption, and demanding equipment requirements. Furthermore, existing methods still have room for improvement in areas such as raw material pretreatment, synergistic optimization of extraction conditions, and essential oil quality control. Patents such as ZL202511774094.2 and ZL202511868869.2 disclose supercritical extraction methods.

[0005] Therefore, developing a supercritical extraction method for tangerine peel essential oil that is highly efficient, energy-saving, and produces high-quality products has significant application value. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention utilizes the principle that supercritical CO2 fluid possesses both gas and liquid properties near its critical point. Under high pressure, the CO2 fluid density is close to that of a liquid, exhibiting a strong dissolving ability for the essential oil components in dried tangerine peel; simultaneously, its viscosity is close to that of a gas, resulting in a large diffusion coefficient and high mass transfer rate, enabling it to rapidly penetrate into the tangerine peel cells, dissolving and carrying out the essential oil components. By controlling parameters such as extraction pressure and temperature, the dissolving ability of the CO2 fluid can be adjusted, selectively extracting the target components. After extraction, multi-stage depressurization reduces the CO2 fluid density, decreasing its dissolving ability, causing the essential oil components to decompose and separate in the separation vessel, thus achieving separation.

[0007] To achieve the above-mentioned objectives, the present invention employs the following technical solution: A type of tangerine peel essential oil, the active ingredients of which include the following parts by weight: D-limonene 30.0-80.0%, γ-terpinene 5.0-15.0%, β-myrcene 0.5-8.0%, α-pinene 0.5-8.0%, and β-pinene 0.2-5.0%.

[0008] This invention discloses a method for preparing tangerine peel essential oil using supercritical CO2 fluid extraction, comprising the following steps: S1. Select dried tangerine peel raw materials, remove impurities, dry at 50-60℃ until the moisture content is 8%-12%, pulverize and sieve, and collect 20-60 mesh dried tangerine peel powder for later use. S2. The tangerine peel powder obtained in S1 is loaded into the extraction vessel, and CO2 is introduced as the extractant. The extraction pressure is set to 15-25 MPa, the extraction temperature to 40-50℃, the extraction time to 60-120 min, and the CO2 flow rate to 20-40 L / h to carry out supercritical fluid extraction. S3. The CO2 fluid carrying essential oil obtained from S2 extraction is sequentially passed through a primary separation vessel and a secondary separation vessel for depressurization and separation. The pressure of the primary separation vessel is set to 8-12 MPa and the temperature is set to 45-55℃; the pressure of the secondary separation vessel is set to 4-6 MPa and the temperature is set to 35-45℃. The tangerine peel essential oil product at the bottom of the secondary separation vessel is collected. S4. The tangerine peel essential oil obtained in S3 is dehydrated and dried with anhydrous sodium sulfate at 35-45℃, and then filtered through a 0.45μm microporous membrane to obtain refined tangerine peel essential oil.

[0009] Preferably, the tangerine peel used in step S1 is Xinhui tangerine peel, which has been aged for 3-10 years.

[0010] Preferably, in step S1, the pulverization is preferably carried out using liquid nitrogen cryogenic pulverization, with a pulverization temperature of -30℃ to -10℃, a pulverization fineness of 40-80 mesh, and a moisture content controlled at 10%-15%.

[0011] Preferably, in step S2, the extraction pressure is preferably 18-22 MPa, the extraction temperature is preferably 42-48℃, and the extraction time is preferably 80-100 min.

[0012] Preferably, in step S2, 5%-10% edible ethanol can be added to the tangerine peel powder as an entrainer.

[0013] Preferably, in step S3, the pressure of the primary separation vessel is preferably 9-11 MPa, and the pressure of the secondary separation vessel is preferably 4.5-5.5 MPa.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: 1. High extraction rate: By optimizing parameters such as raw material particle size, extraction pressure, temperature, and time, this invention achieves an extraction rate of 2.5%-3.2% for tangerine peel essential oil, which is significantly higher than that of traditional steam distillation (1.2%-1.8%) and conventional supercritical extraction (1.8%-2.2%).

[0015] 2. High product quality: This invention uses a low-temperature extraction process, which avoids the destruction of heat-sensitive components. The resulting essential oil is bright yellow and clear, with a pure and rich aroma, and retains the original natural flavor characteristics of dried tangerine peel.

[0016] 3. No solvent residue: Using CO2 as the extractant, there is no toxic solvent residue in the product, which meets the requirements of green environmental protection and can be directly applied to food, cosmetics, medicine and other fields.

[0017] 4. Selectivity and controllability: By adjusting the extraction pressure and temperature, essential oil components with different boiling points can be selectively extracted, realizing the artificial control of the essential oil composition and meeting different application needs.

[0018] 5. High separation efficiency: The multi-stage separation technology enables preliminary classification of essential oil components, resulting in a more uniform product while improving separation efficiency.

[0019] 6. Lower energy consumption: Compared with existing supercritical extraction technology, this invention optimizes parameters to appropriately reduce extraction pressure and reduce energy consumption while ensuring extraction rate. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below with reference to embodiments, but this does not limit the present invention to the scope of the embodiments described. Process parameters not specified in the embodiments of this application can be performed according to conventional methods, and all raw materials used can be obtained through commercial channels. Example 1

[0021] Step 1: Raw material pretreatment Take 10 kg of Xinhui tangerine peel that has been aged for 5 years, remove impurities, dry it at 55℃ until the moisture content is 10%, pulverize it with a pulverizer and pass it through a 40-mesh sieve, and collect the tangerine peel powder for later use.

[0022] Step 2: Supercritical CO2 extraction The tangerine peel powder obtained in step 1 was loaded into a 10L extraction vessel, and CO2 was introduced as the extractant. The extraction pressure was set to 20MPa, the extraction temperature to 45℃, the extraction time to 90min, and the CO2 flow rate to 30L / h for supercritical fluid extraction.

[0023] Step 3: Multi-stage separation The CO2 fluid carrying essential oil obtained from step 2 was sequentially passed through a primary separator and a secondary separator for depressurization and separation. The pressure in the primary separator was set to 10 MPa and the temperature to 50°C; the pressure in the secondary separator was set to 5 MPa and the temperature to 40°C. The tangerine peel essential oil product at the bottom of the secondary separator was collected.

[0024] Step 4: Refining Process The tangerine peel essential oil obtained in step 3 was dehydrated and dried at 40°C using anhydrous sodium sulfate, and then filtered through a 0.45μm microporous membrane to obtain 298g of refined tangerine peel essential oil with an extraction rate of 2.98%.

[0025] Gas chromatography-mass spectrometry analysis revealed that the main components of the obtained tangerine peel essential oil were D-limonene (68.5%), γ-terpinene (12.3%), β-myrcene (5.2%), α-pinene (2.8%), and β-pinene (1.6%). Example 2

[0026] Step 1: Raw material pretreatment Take 10kg of Xinhui tangerine peel that has been aged for 3 years, remove impurities, and use liquid nitrogen for low-temperature pulverization at a temperature of -20℃. After pulverization, pass it through a 60-mesh sieve and control the moisture content to 12%.

[0027] Step 2: Supercritical CO2 extraction 8% edible ethanol was added to the dried tangerine peel powder as an entrainer, mixed well, and then loaded into an extraction vessel. The extraction pressure was set to 18 MPa, the extraction temperature to 42℃, the extraction time to 100 min, and the CO2 flow rate to 25 L / h for supercritical fluid extraction.

[0028] Step 3: Multi-stage separation The pressure in the primary separator was set to 9 MPa and the temperature to 48°C; the pressure in the secondary separator was set to 5 MPa and the temperature to 42°C. The tangerine peel essential oil product from the bottom of the secondary separator was collected.

[0029] Step 4: Refining Process The tangerine peel essential oil was dehydrated and dried at 38°C using anhydrous sodium sulfate, and then filtered through a 0.45μm microporous membrane to obtain 312g of refined tangerine peel essential oil with an extraction rate of 3.12%. Example 3

[0030] Step 1: Raw material pretreatment Take 10 kg of Xinhui tangerine peel that has been aged for 8 years, remove impurities, dry it at 50℃ until the moisture content is 8%, pulverize it and pass it through a 50-mesh sieve.

[0031] Step 2: Supercritical CO2 extraction The extraction pressure was set at 22 MPa, the extraction temperature at 48℃, the extraction time at 80 min, and the CO2 flow rate at 35 L / h for supercritical fluid extraction.

[0032] Step 3: Multi-stage separation The pressure in the primary separator was set to 11 MPa and the temperature to 52°C; the pressure in the secondary separator was set to 4.5 MPa and the temperature to 38°C. The tangerine peel essential oil product from the bottom of the secondary separator was collected.

[0033] Step 4: Refining Process The tangerine peel essential oil was dehydrated and dried at 42°C using anhydrous sodium sulfate, and then filtered through a 0.45μm microporous membrane to obtain 285g of refined tangerine peel essential oil with an extraction rate of 2.85%.

[0034] Comparative Example 1 (Steam Distillation Method) 10 kg of the same dried tangerine peel as in Example 1 was taken, pulverized, and passed through a 40-mesh sieve. The mixture was then placed in a steam distillation apparatus, soaked in water for 2 hours, and then heated and distilled for 6 hours. The distillate was collected, separated by an oil-water separator, and dried with anhydrous sodium sulfate to obtain 162 g of dried tangerine peel essential oil, with an extraction rate of 1.62%. The obtained essential oil was dark in color, had a weak aroma, and a burnt smell.

[0035] Comparative Example 2 (Conventional Supercritical Extraction Method) 10 kg of the same dried tangerine peel as in Example 1 was taken, and supercritical CO2 extraction was performed according to the methods described in the literature, such as existing technologies, including patents ZL202511774094.2 and ZL202511868869.2, which disclose supercritical extraction methods. (Extraction pressure 25 MPa, extraction temperature 50℃, extraction time 120 min, CO2 flow rate 20 L / h) to obtain 208 g of dried tangerine peel essential oil, with an extraction rate of 2.08%.

[0036] To further verify the influence of process parameters on the extraction effect of tangerine peel essential oil, we designed several parallel experiments based on Examples 1-3, and systematically investigated the effects of each key factor using the single-variable method. Each experiment was conducted in triplicate, and the average value was taken as the result. The specific data and analysis are as follows.

[0037] 1. Parallel experiments for Example 1 (single-factor pressure and temperature) Background: In Example 1, based on Comparative Example 2 (25 MPa, 50 °C), the pressure was adjusted to 22 MPa and the temperature to 48 °C, resulting in an increase in the extraction rate from 2.08% to 2.85% and the D-limonene content from 60.1% to 70.3%. To further determine the optimal pressure and temperature range, the following experiments were conducted.

[0038] 1.1 Single-factor experiment on pressure Fixed conditions: temperature 48℃, time 90 min, CO2 flow rate 30 L / h, raw material particle size same as comparative example 2. Table 1. Single-factor pressure experiment.

[0039] Evaluation: Table 1 shows that as the pressure increases, the extraction rate and D-limonene content first increase and then decrease, with 22 MPa being the optimal value. Too low a pressure (18 MPa) results in insufficient extraction capacity; too high a pressure (>25 MPa) may lead to co-extraction of impurities, which could reduce the content of active ingredients and aroma quality.

[0040] 1.2 Temperature Single-Factor Experiment Fixed conditions: pressure 22MPa, time 90min, CO2 flow rate 30L / h, raw material particle size same as Comparative Example 2, Table 2. Temperature single-factor experiment.

[0041]

[0042] Evaluation: Table 2 shows that temperature has a significant impact on extraction selectivity. The active ingredients are most fully dissolved at 48℃, while excessively high temperatures (>50℃) may damage heat-sensitive components or cause a burnt taste.

[0043] 2. Parallel experiments for Example 2 (entrainer concentration and type) Background: In Example 2, 8% edible ethanol was added to the oil extracted in Example 1, increasing the extraction rate to 3.12%. The essential oil turned light yellow and transparent, with a delicate and elegant aroma. To further optimize the entrainer, the following experiments were conducted.

[0044] 2.1 Single-factor experiment on entrainer concentration Fixed conditions: pressure 22 MPa, temperature 48℃, time 90 min, CO2 flow rate 30 L / h, raw material particle size same as in Example 1, entrainer is edible ethanol. Table 3. Single-factor experiment on entrainer concentration.

[0045] Evaluation: Table 3 shows that adding ethanol can improve the extraction rate of polar components, but excessive amounts can dilute or entrain non-target components, leading to a decrease in D-limonene content and poor aroma harmony. 8% is the optimal concentration that balances extraction rate and quality.

[0046] 2.2 Comparison Experiment of Entrainer Types Fixed conditions: pressure 22MPa, temperature 48℃, time 90min, CO2 flow rate 30L / h, raw material particle size same as in Example 1, entrainer concentration 8%. Table 4. Comparison experiment of entrainer types.

[0047]

[0048] Evaluation: Edible ethanol (95%) showed the best results, while water was the least effective entrainer and was prone to emulsification. Propylene glycol, while improving the extraction of some polar components, did not significantly enhance aroma.

[0049] 3. Parallel experiments for Example 3 (raw material particle size and extraction time) Background: In Example 3, the raw materials were pulverized to 40 mesh and the extraction time was extended to 150 min, based on Example 2. The extraction rate was 2.98%, and the D-limonene content was 68.5%. To investigate the effect of particle size and time, the following experiments were conducted.

[0050] 3.1 Single-factor experiment on raw material particle size Fixed conditions: pressure 22 MPa, temperature 48℃, time 120 min, CO2 flow rate 30 L / h, entrainer 8% ethanol. Table 5. Single-factor experiment on raw material particle size.

[0051]

[0052] Evaluation: Table 5 shows that excessively coarse particle size (20 mesh) results in high mass transfer resistance and low extraction rate; excessively fine particle size (>60 mesh) easily causes bed compaction, channel blockage, and may extract more impurities. 40 mesh is the optimal choice.

[0053] 3.2 Single-factor experiment on extraction time Fixed conditions: pressure 22 MPa, temperature 48℃, particle size 40 mesh, CO2 flow rate 30 L / h, entrainer 8% ethanol. Table 6. Single-factor experiment on extraction time.

[0054]

[0055] Evaluation: Table 6 shows that the extraction rate increases with time, but plateauses after 120 min. Excessive extraction time may lead to degradation of some components or dissolution of impurities. The D-limonene content decreases after 150 min. Considering both efficiency and quality, 120–150 min is the optimal range.

[0056] Through the above parallel experiments, the effects of pressure, temperature, entrainer concentration, entrainer type, raw material particle size, and extraction time on the extraction efficiency of tangerine peel essential oil were systematically investigated using the single-variable method. The results showed that: The 22 MPa and 48°C selected in Example 1 are within the optimal pressure-temperature combination range, which can effectively improve the D-limonene content and aroma quality.

[0057] Example 2: Adding 8% edible ethanol as an entrainer significantly improved the extraction rate while maintaining a good aroma, which was superior to other concentrations and types.

[0058] Example 3 optimized the raw material particle size to 40 mesh and the extraction time to 120-150 min, achieving a balance between mass transfer efficiency and product quality.

[0059] The parallel experimental data above fully demonstrate the rationality and superiority of the process parameters selected in Examples 1-3, providing a solid experimental basis for the present invention.

[0060] Alternatives to the present invention include: 1. The extractant can be a mixture of CO2 and other green solvents (such as propane and butane); 2. The tangerine peel can be pretreated with enzymes before extraction to improve the extraction rate; 3. Subcritical extraction technology can be used as an alternative to achieve efficient extraction under lower pressure.

Claims

1. A type of dried tangerine peel essential oil, characterized in that, Its active ingredients consist of the following components by weight: D-limonene 30.0-80.0%, γ-terpinene 5.0-15.0%, β-myrcene 0.5-8.0%, α-pinene 0.5-8.0%, and β-pinene 0.2-5.0%.

2. A method for preparing tangerine peel essential oil according to claim 1 using supercritical CO2 fluid extraction, characterized in that, Includes the following steps: S1. Select dried tangerine peel raw materials, remove impurities, dry at 50-60℃ until the moisture content is 8%-12%, pulverize and sieve, and collect 20-60 mesh dried tangerine peel powder for later use. S2. The tangerine peel powder obtained in S1 is loaded into the extraction vessel, and CO2 is introduced as the extractant. The extraction pressure is set to 15-25 MPa, the extraction temperature to 40-50℃, the extraction time to 60-120 min, and the CO2 flow rate to 20-40 L / h to carry out supercritical fluid extraction. S3. The CO2 fluid carrying essential oil obtained from S2 extraction is sequentially passed through a primary separation vessel and a secondary separation vessel for depressurization and separation. The pressure of the primary separation vessel is set to 8-12 MPa and the temperature is set to 45-55℃; the pressure of the secondary separation vessel is set to 4-6 MPa and the temperature is set to 35-45℃. The tangerine peel essential oil product at the bottom of the secondary separation vessel is collected. S4. The tangerine peel essential oil obtained in S3 is dehydrated and dried with anhydrous sodium sulfate at 35-45℃, and then filtered through a 0.45μm microporous membrane to obtain refined tangerine peel essential oil.

3. The method for preparing tangerine peel essential oil by supercritical CO2 fluid extraction according to claim 2, characterized in that, In step S1, the tangerine peel is preferably Xinhui tangerine peel, with an aging period of 3-10 years.

4. The method for preparing tangerine peel essential oil by supercritical CO2 fluid extraction according to claim 2, characterized in that, In step S1, the preferred method for pulverization is liquid nitrogen cryogenic pulverization, with a pulverization temperature of -30℃ to -10℃, a pulverization fineness of 40-80 mesh, and a moisture content controlled at 10%-15%.

5. The method for preparing tangerine peel essential oil by supercritical CO2 fluid extraction according to claim 2, characterized in that, In step S2, the extraction pressure is preferably 18-22 MPa, the extraction temperature is preferably 42-48℃, and the extraction time is preferably 80-100 min.

6. The method for preparing tangerine peel essential oil by supercritical CO2 fluid extraction according to claim 2, characterized in that, In step S2, 5%-10% edible ethanol can be added to the tangerine peel powder as an entrainer.

7. The method for preparing tangerine peel essential oil by supercritical CO2 fluid extraction according to claim 1, characterized in that, In step S3, the pressure of the primary separation vessel is preferably 9-11 MPa, and the pressure of the secondary separation vessel is preferably 4.5-5.5 MPa.

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