Patchouli oil and preparation method thereof

Abstract

The invention provides patchouli oil and a preparation method thereof, and the preparation method comprises the following steps: S1, removing residual roots and impurities from dried patchouli decoction pieces, then separating patchouli leaves and patchouli stems, and respectively crushing and sieving to obtain patchouli leaf powder and patchouli stem powder; and S2, filling the pogostemon cablin leaf powder obtained in the step S1 and / or the pogostemon cablin stem powder obtained in the step S1 into a supercritical carbon dioxide extraction kettle, extracting for 2 hours, collecting volatile oil from a separation port, and dehydrating the volatile oil to obtain the pogostemon cablin oil. The preparation method disclosed by the invention can effectively improve the extraction rate and the effective component content of the patchouli oil.

Description

Technical Field

[0001] The invention relates to patchouli oil and a preparation method thereof. Background Art

[0002] Patchouli (Pogostemon cablin (Blanco) Benth.), also known as patchouli and patchouli, is a herbaceous plant of the genus Patchouli in the family Lamiaceae. It is used as both a medicinal and spice plant. The medicinal part is the dried aerial parts, generally harvested when the branches and leaves are lush and then dried in the sun and at night. Patchouli is native to subtropical regions such as Indonesia and Malaysia and is currently cultivated in Zhaoqing, Zhanjiang, Guangxi, and Hainan in my country.

[0003] Patchouli is a commonly used aromatic dehumidifying herb with a pungent flavor and slightly warm properties. It enters the spleen, stomach, and lung meridians, and has the effects of clearing turbidity, soothing the stomach and stopping vomiting, and relieving summer heat. Clinically, it is primarily used to treat dampness and turbidity blocking the middle of the body, abdominal distension and vomiting, symptoms of summer dampness, chest tightness and discomfort, cold-dampness-induced summer heat retention, abdominal pain, vomiting, and nasal sinus headaches. Patchouli is a key component of traditional Chinese medicines such as Baoji Pills, Huoxiang Zhengqi Decoction, and Huodan Pills.

[0004] Patchouli oil is a clear, reddish-brown or greenish-brown liquid with a distinctive patchouli aroma. It is pungent and slightly warm, and is miscible with chloroform, ether, or petroleum ether. Its main components are patchouli alcohol and patchouli ketone, so these two components are often used as effective indicators in patchouli oil extraction research.

[0005] Patchouli alcohol, also known as patchouli alcohol, is a tricyclic sesquiterpene compound found in natural plants. Its molecular formula is C 15 H 26 O, with a molecular weight of 222.37 and the structural formula shown below. Patchouli alcohol monomer is a colorless crystal with a light patchouli aroma. It has a melting point of 55-56°C, a boiling point of 280°C (at normal pressure), a relative density of 1.0284, and an optical rotation of -97.4° (c=24, chloroform). It is insoluble in water but soluble in alcohol, ether, and common organic solvents.

[0006]

[0007] Patchouli ketone is an active ingredient extracted and separated from the volatile oil of patchouli. It is a small molecule lactone compound, presenting as colorless needle-shaped crystals with a melting point of 32.5-33°C. It is easily soluble in alkaline aqueous solutions and general organic solvents. Its molecular weight is 224.26 and its molecular formula is C 12 H 16 O4, chemical name is 3-(4'-methylpentanoyl)-6-methyl-3,4-dihydro-1,2-pyran-2,4-dione, and its structural formula is shown below.

[0008]

[0009] Patchouli oil, as an important extract of patchouli, is also an important intermediate product and raw material in industrial production. For example, China's GB2760-96 regulations allow patchouli oil to be used as a food flavoring, mainly used in cola-type beverages as a food flavoring. As an extract of aromatic medicinal materials, patchouli oil is also an important natural flavoring. Because of its excellent fragrance-fixing properties, patchouli oil is also a commonly used fixative and is widely used in daily perfumery. At the same time, patchouli oil is a volatile oil that has the effects of inhibiting fungi, treating axillary odor and athlete's foot, and treating superficial fungal infections of the skin. It can also be used to treat skin problems such as fungal infections and skin inflammation. Therefore, optimizing the quality of patchouli oil extraction is one of the important issues to improve the quality of traditional Chinese medicine and extend the industrial chain.

[0010] Common methods for extracting patchouli oil include steam extraction, Soxhlet extraction, organic solvent extraction, and supercritical carbon dioxide extraction. Traditionally, patchouli oil is extracted through steam distillation, a mature and widely used method in industrial production. However, this method is time-consuming, energy-intensive, and has low extraction efficiency. Therefore, exploring new patchouli oil extraction methods is an effective way to improve efficiency, reduce costs, and extend the industry chain.

[0011] Among the four common oil extraction methods, supercritical carbon dioxide extraction has the advantages of low temperature, high efficiency, and no reagent residue. At room temperature (35-45°C) and carbon dioxide conditions, due to the closed conditions, the heat-sensitive components in the medicinal materials are not easily oxidized and dissipated during extraction, which can effectively reduce the loss of effective ingredients. After the extraction is completed, when the extract enters the separation kettle, due to the pressure difference between the extraction kettle and the separation kettle, the extract can be quickly separated into two phases, saving time and improving efficiency. Carbon dioxide, as an extraction medium, is widely available and is relatively cheap to produce compared to other gases. It can also be recycled in the production process, which can effectively reduce the cost of use.

[0012] The environmentally friendly nature of supercritical carbon dioxide extraction (SCCO) has broad applications. CO2 is readily available, readily recovered, and rarely reacts with active ingredients, making it highly safe and promising for future development. Patchouli, as an aromatic herb, is well-suited for industrializing SCCO extraction.

[0013] In existing literature, domestic and international researchers studying the supercritical carbon dioxide extraction of patchouli oil have primarily focused on the extraction conditions of temperature, extraction pressure, carbon dioxide flow rate, and particle size. The experimental conditions used in existing domestic literature include an extraction pressure of 9-30 MPa, an extraction temperature of 33-50°C, an extraction time of 74-150 minutes, a particle size of 0.3-0.6 mm, and a carbon dioxide flow rate of 1-20 L / H.

[0014] Although domestic and foreign scholars have achieved certain results in the research of new methods for extracting patchouli oil, there are still some problems that need to be solved. Based on the differences between the current standards of the Chinese Pharmacopoeia and international standards, the following three problems are considered.

[0015] 1. The stem-to-leaf ratio is unclear. The main components of patchouli oil are patchouli alcohol and patchouli ketone. Patchouli alcohol is mainly sourced from patchouli leaves, while patchouli ketone is mainly sourced from patchouli stems. The oil extraction rates of stems and leaves vary greatly. When the stem-to-leaf ratio is unclear, only discussing the extraction rate will affect the accuracy of the conclusion. Existing methods do not clearly define the impact of the patchouli stem-to-leaf ratio on the extraction efficiency of different methods, nor do they explore the changes in the effective ingredients when different stem-to-leaf ratios are used to extract patchouli oil.

[0016] 2. Different standards lead to differences in the physical properties of patchouli oil. Due to the differences between the requirements for patchouli oil in the Chinese Pharmacopoeia and international standards, patchouli oil extracted domestically is not applicable to international standards. Patchouli oil extracted according to the Chinese Pharmacopoeia will not meet the standards when measuring the acid value. The common reason for the acid value of essential oils not meeting the standards is the fermentation of raw materials, and the use of patchouli stems will also affect the acid value. Since the Chinese Pharmacopoeia only has a minimum proportion requirement for patchouli leaves, a certain amount of patchouli stems will still be mixed in actual production. Patchouli stems are the main source of patchouli ketone, and in international standards, acid value determination cannot be applied to essential oils containing lactones. The Chinese alias for patchouli ketone is 4-hydroxy-6-methyl-3-(4-methyl-1-oxopentyl)-2H-pyran-2-one, which has a lactone structure. According to the experimental principle of determining the acid value of essential oils, it is believed that patchouli ketone will have a greater impact on the acid value.

[0017] 3. Insufficient research on supercritical separation pressure. Regarding supercritical carbon dioxide extraction, existing papers have focused more on temperature and extraction pressure, but less on separation pressure. Only a few papers in the food industry have mentioned this. However, separation pressure can affect the efficiency of extracts and, as a crucial condition for supercritical carbon dioxide extraction, warrants further study.

[0018] In summary, while there is considerable research on supercritical carbon dioxide extraction of patchouli oil, there is limited research on the stem-to-leaf ratio and separation pressure. Furthermore, existing research often utilizes organic reagents such as carriers and modifiers. Given that supercritical extraction instruments are pressurized and pose a certain risk in industrial production, it is necessary to explore methods for extracting patchouli oil without the use of carriers. Summary of the Invention

[0019] The technical problem to be solved by the present invention is to provide a preparation method of patchouli oil, which can effectively improve the extraction rate and active ingredient content of patchouli oil.

[0020] In order to solve the above technical problems, the technical solution of the present invention is:

[0021] A method for preparing patchouli oil comprises the following steps:

[0022] S1. The dried patchouli pieces are free of roots and impurities, and the patchouli leaves and stems are separated and pulverized and sieved to obtain patchouli leaf powder and patchouli stem powder;

[0023] S2. The patchouli leaf powder and / or the patchouli stem powder obtained in step S1 are charged into a supercritical carbon dioxide extraction vessel and extracted for 2 hours. The volatile oil is collected from the separation port and the volatile oil is dehydrated to obtain patchouli oil.

[0024] Furthermore, in step S1 of the present invention, a No. 2 sieve is used for crushing and screening.

[0025] Furthermore, in step S2 of the present invention, the mass ratio of the patchouli leaf powder obtained in step S1 to the patchouli stem powder obtained in step S1 is (0-1):(1-0).

[0026] Furthermore, in step S2 of the present invention, the extraction temperature of the supercritical carbon dioxide extraction kettle is 40-50° C., the extraction pressure is 9-11 MPa, the separation pressure is 7.5-8.5 MPa, and the flow rate of carbon dioxide is 20 L / h.

[0027] Another technical problem to be solved by the present invention is to provide patchouli oil obtained by the above preparation method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The invention uses a supercritical carbon dioxide extraction method to extract patchouli leaves and patchouli stems to prepare patchouli oil, and defines specific extraction conditions, thereby effectively improving the extraction rate and active ingredient content of the patchouli oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 This is a trend chart showing the relationship between the acid value of patchouli oil and the content of patchouli alcohol and patchouli ketone. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to specific embodiments. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention but are not intended to limit the present invention.

[0033] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources. Specifically, patchouli was purchased from the Patchouli GAP Planting Base of Sinopharm Dezhong Pharmaceutical (Huangtian Town, Sihui City, Zhaoqing City, Guangdong Province).

[0034] The equipment used in the following examples are HA230-50-(5+5)-C supercritical carbon dioxide extraction kettle, Hua'an Supercritical Extraction Co., Ltd., Nantong, China; 7890B-gas chromatograph, Agilent; BP211D electronic analytical balance, Mettler-Sartorius.

[0035] Example 1

[0036] Follow these steps to prepare patchouli oil:

[0037] S1. The dried patchouli pieces were free of roots and impurities, and the patchouli leaves and stems were separated and pulverized through a No. 2 sieve to obtain patchouli leaf powder and patchouli stem powder;

[0038] S2. The patchouli leaf powder obtained in step S1 and the patchouli stem powder obtained in step S1 in a mass ratio of 1:1 are charged into a supercritical carbon dioxide extraction kettle and extracted for 2 hours. The volatile oil is collected from the separation port, and the volatile oil is dehydrated to obtain patchouli oil; the extraction temperature of the supercritical carbon dioxide extraction kettle is 45°C, the extraction pressure is 10 MPa, the separation pressure is 7.5 MPa, and the carbon dioxide flow rate is 20 L / h.

[0039] Example 2

[0040] Follow these steps to prepare patchouli oil:

[0041] S1. The dried patchouli pieces were free of roots and impurities, and the patchouli leaves and stems were separated and pulverized through a No. 2 sieve to obtain patchouli leaf powder and patchouli stem powder;

[0042] S2. The patchouli stem powder obtained in step S1 is charged into a supercritical carbon dioxide extraction kettle and extracted for 2 hours. The volatile oil is collected from the separation port, and the volatile oil is dehydrated to obtain patchouli oil; the extraction temperature of the supercritical carbon dioxide extraction kettle is 40°C, the extraction pressure is 11 MPa, the separation pressure is 8 MPa, and the carbon dioxide flow rate is 20 L / h.

[0043] Example 3

[0044] Follow these steps to prepare patchouli oil:

[0045] S1. The dried patchouli pieces were free of roots and impurities, and the patchouli leaves and stems were separated and pulverized through a No. 2 sieve to obtain patchouli leaf powder and patchouli stem powder;

[0046] S2. The patchouli leaf powder obtained in step S1 is charged into a supercritical carbon dioxide extraction vessel and extracted for 2 hours. The volatile oil is collected from the separation port and the volatile oil is dehydrated to obtain patchouli oil. The supercritical carbon dioxide extraction vessel is operated at an extraction temperature of 50°C, an extraction pressure of 9 MPa, a separation pressure of 8.5 MPa, and a carbon dioxide flow rate of 20 L / h.

[0047] Experimental Example 1: Orthogonal Experiment

[0048] Using L9(3 3 The orthogonal table method was used to design the experimental conditions for supercritical carbon dioxide extraction of patchouli oil. This experiment selected three key influencing factors: temperature (A), extraction pressure (B), and separation pressure (C). A three-level, three-factor orthogonal design was employed. The factor level design is shown in Table 1, and the specific experimental plan is shown in Table 2.

[0049] Table 1 Experimental factor levels

[0050]

[0051] Table 2 Orthogonal experimental design table

[0052]

[0053]

[0054] The orthogonal array experimental steps for supercritical carbon dioxide extraction of patchouli oil are as follows:

[0055] S1. The dried patchouli pieces were free of roots and impurities, and the patchouli leaves and stems were separated and pulverized through a No. 2 sieve to obtain patchouli leaf powder and patchouli stem powder;

[0056] S2. Patchouli leaf powder and patchouli stem powder obtained in step S1 at a mass ratio of 1:4 were charged into a supercritical carbon dioxide extraction kettle and extracted for 2 h according to the conditions in Table 2. Volatile oil was collected from the separation port, dehydrated, and sealed and stored at 0°C to obtain patchouli oil. The oil extraction rate was calculated, and the orthogonal statistical method was used to calculate the primary and secondary influencing factors. The experimental results are shown in Table 3.

[0057] Oil extraction rate is calculated according to Calculate, where moil is the mass of patchouli oil obtained by extraction, and M is the total mass of patchouli leaf powder and patchouli stem powder mixed evenly in proportion.

[0058] Table 3 Orthogonal experiment results

[0059]

[0060] According to the three-level, three-factor orthogonal table method, the optimal levels are A2B3C3, namely 45°C, extraction pressure 11MPa, and separation pressure 7.5MPa. Among them, the influencing factors are: separation pressure > extraction pressure > temperature, and separation pressure has the most significant impact on the yield of patchouli oil. Since the yield difference between extraction pressures of 10MPa and 11MPa is not significant, and when other conditions are the same, patchouli oil extracted at 11MPa contains more insoluble matter than patchouli oil extracted at 10MPa, 10MPa is selected for economic reasons. In summary, the conditions for supercritical carbon dioxide extraction of patchouli oil are 45°C, extraction pressure 10MPa, separation pressure 7.5MPa, and extraction time of 2h.

[0061] Experimental Example 2: Stem-Leaf Ratio Experiment

[0062] Stem-to-leaf ratio Calculations were performed where mleaves represents the mass of patchouli leaf powder, and mstems represents the mass of patchouli stem powder. Therefore, in Experimental Example 2, a stem-to-leaf ratio of 100% represents pure patchouli leaf, while a stem-to-leaf ratio of 0% represents pure patchouli stem. The results of supercritical carbon dioxide extraction of patchouli oil at different stem-to-leaf ratios are shown in Table 4.

[0063] Table 4 Results of supercritical carbon dioxide extraction of patchouli oil with different stem-leaf ratios

[0064]

[0065] The results in Table 4 show that, at the same feed rate, the oil extraction rate follows a trend of pure patchouli leaves > 50% > pure patchouli stems. Under these conditions, supercritical CO2 exhibits a certain selective bias toward patchouli leaves and stems. If supercritical CO2 were unbiased under these conditions, the oil extraction rate for patchouli oil with a 50% stem-to-leaf ratio would be around 1.39%, with a deviation of more than 5%. Therefore, it is believed that the components in patchouli leaves are more readily extracted by supercritical CO2 under these conditions.

[0066] Experimental Example 3: Determination of Patchouli Alcohol Content

[0067] Preparation of the test sample: Take 0.1 g of patchouli oil, accurately weigh it, place it in a 10 mL volumetric flask, dissolve it in n-hexane and dilute it to the scale, shake it well, and use it as the test solution.

[0068] Preparation of reference solution: Take an appropriate amount of Patchouli alcohol reference substance, accurately weigh it, and add n-hexane to prepare a solution containing 6 g per 1 mL.

[0069] Chromatographic conditions: capillary column with 5% phenylmethylpolysiloxane as the stationary phase (column length, column length, inner diameter, inner diameter, film thickness, 0.254 μm); programmed column temperature: initial temperature 180°C, hold for 10 min, increase to 230°C at a rate of 5°C per minute, hold for 3 min; detector temperature, 280°C, injection port temperature, 280°C; split injection, split ratio, 10:1.

[0070] The percentage content of Patchouli alcohol was calculated according to the following formula:

[0071]

[0072] The experimental results of exploring the optimal conditions for extracting patchouli alcohol from patchouli oil using supercritical carbon dioxide using an orthogonal table are shown in Table 5.

[0073] Table 5 Patchouli alcohol content in supercritical carbon dioxide extraction of patchouli oil under orthogonal table

[0074]

[0075]

[0076] The results in Table 5 show that there's no one-to-one correspondence between temperature, extraction pressure, separation pressure, oil extraction rate, and the percentage of patchouli alcohol. Therefore, substituting the data in Table 5 into an orthogonal table, the optimal conditions for patchouli alcohol production are 45°C, an extraction pressure of 10 MPa, and a separation pressure of 8.5 MPa.

[0077] The experimental results of the patchouli alcohol content in patchouli oil with different stem-leaf ratios extracted by supercritical carbon dioxide are shown in Table 6.

[0078] Table 6 Patchouli alcohol content in patchouli oil extracted with different stem-leaf ratios by supercritical carbon dioxide

[0079]

[0080] According to the results in Table 6, there are differences in the content of patchouli alcohol when patchouli oil is extracted with supercritical carbon dioxide under different stem-leaf ratios. Patchouli alcohol also exists in patchouli stems. The percentage of patchouli alcohol extracted under these supercritical conditions is 15.24%. Although there is a certain gap from the standard of 26% for patchouli oil in the Pharmacopoeia of the People's Republic of China, it also shows that patchouli stems can also be used as a raw material for the extraction of patchouli alcohol.

[0081] At the same time, Table 6 shows that the percentage content of patchouli alcohol in patchouli oil with a stem-leaf ratio of 50% and patchouli oil from pure patchouli leaves are similar. Therefore, the content of patchouli alcohol is used as a comparison value, that is, the content of patchouli alcohol = patchouli oil mass × oil extraction rate × percentage content of patchouli alcohol. It can be concluded that the ratio of the extraction amount of patchouli alcohol is pure patchouli leaves: 50% stem-leaf ratio: pure patchouli stems = 3.8:2:1.

[0082] Experimental Example 4: Determination of Patchouli Ketone Content

[0083] Preparation of the test sample: Take 0.1 g of patchouli oil, accurately weigh it, place it in a 10 mL volumetric flask, dissolve it in n-hexane and dilute it to the scale, shake it well, and use it as the test solution.

[0084] Preparation of reference solution: Accurately weigh an appropriate amount of n-octadecane and add n-hexane to prepare a solution containing 15 mg per 1 mL as the internal standard solution. Accurately weigh 6 g of patchouli ketone reference substance to prepare the internal standard solution in a 10 mL volumetric flask. Accurately add 1 mL of the internal standard solution and dilute to the mark with n-hexane. Shake well to prepare the reference solution.

[0085] Chromatographic conditions: HP-5 capillary column (cross-linked 5% phenylmethylpolysiloxane as stationary phase); temperature program: initial temperature 150°C, hold for 23 min, increase to 230°C at a rate of 8°C per minute, hold for 2 min; detector temperature, 280°C, injection port temperature, 280°C.

[0086] The percentage content of patchouli ketone was calculated according to the following formula:

[0087]

[0088] The experimental results of exploring the optimal conditions for supercritical carbon dioxide extraction of patchouli ketone content in patchouli oil using orthogonal array are shown in Table 7.

[0089] Table 7 Content of patchouli ketone in supercritical carbon dioxide extraction of patchouli oil under orthogonal table

[0090]

[0091] According to the results in Table 7, there are differences in the content of patchouli ketone when supercritical carbon dioxide extraction of patchouli oil is carried out under different conditions, but the content of patchouli ketone does not show a single trend with the extraction conditions. Therefore, when substituted into the orthogonal table for calculation, the optimal conditions for patchouli ketone are 45°C, extraction pressure 11 MPa, and separation pressure 8.5 MPa.

[0092] The experimental results of the patchouli ketone content in patchouli oil with different stem-leaf ratios extracted by supercritical carbon dioxide are shown in Table 8.

[0093] Table 8 Content of patchouli ketone in patchouli oil with different stem-leaf ratios extracted by supercritical carbon dioxide

[0094]

[0095] According to the results in Table 8, patchouli oils with different stem-leaf ratios all contain a certain amount of patchouli ketone, and the oil extraction rate is inversely proportional to the content of patchouli ketone and directly proportional to the specific gravity of patchouli stems. That is, the higher the specific gravity of patchouli stems, the higher the content of patchouli ketone, and the oil extraction rate will decrease inversely.

[0096] Since the oil extraction rates of the three are quite different, the content of patchouli ketone is used as a comparison value, that is, the content of patchouli ketone = patchouli oil mass × oil extraction rate × percentage content of patchouli ketone for calculation. It can be concluded that the ratio of the extraction amount of patchouli ketone is pure patchouli leaves: 50% stem-leaf ratio: pure patchouli stems = 1.56:1.02:1.

[0097] Experimental Example 5: Acid Value Determination

[0098] Weigh 2 ± 0.05 g of patchouli oil, accurate to 0.5 mg, into a saponification flask and dissolve in 5 mL of 95% ethanol / water. Add 5 drops of phenolphthalein solution as an indicator and neutralize with calibrated 0.1 N potassium hydroxide in ethanol in a 25 mL burette. The 0.1 N potassium hydroxide in ethanol solution should be prepared fresh on the day of use, so the actual concentration of the potassium hydroxide in ethanol solution shown in the table may vary.

[0099] The acid value is calculated according to the following formula:

[0100]

[0101] Where v is the volume of the corrected 0.1N potassium hydroxide ethanol solution consumed, and m is the mass of patchouli oil. Since acidity is affected by lactones, the stem-to-leaf ratio was selected as the variable for acid value determination.

[0102] The experimental results of the acid value of patchouli oil with different stem-leaf ratios extracted by supercritical carbon dioxide are shown in Table 9.

[0103] Table 9 Acid values ​​of patchouli oil extracted with different stem-leaf ratios by supercritical carbon dioxide

[0104]

[0105] Note: The potassium hydroxide ethanol concentration in Table 9 is 0.0934 mol / L after correction.

[0106] The results in Table 9 show that there is a clear positive correlation between the stem-to-leaf ratio of patchouli and the acidity of patchouli oil, with a deviation of less than 5%. The acidity follows the order of pure patchouli leaf > 50% stem-to-leaf ratio > pure patchouli stem. As the proportion of patchouli stem increases, the acidity also increases.

[0107] In summary, the experimental conditions of the present invention adopt L9(3 3 ) Orthogonal table design was used to screen the conditions through experiments. The oil extraction rate results in Table 3 were obtained through experiments. Based on the actual experimental conditions, the following conditions were selected: 45°C, extraction pressure 10MPa, separation pressure 7.5MPa, and extraction time 2h.

[0108] However, it was found that the oil extraction rate and the active ingredient content did not correspond one-to-one. Therefore, based on the data in Tables 5 and 7, the percentage content and oil extraction rate were combined, and the extraction amount of the active ingredient was used as a reference index. The optimal extraction conditions were calculated using an orthogonal table. The optimal conditions for patchouli alcohol were 45°C, an extraction pressure of 10 MPa, and a separation pressure of 8.5 MPa, while the optimal conditions for patchouli ketone were 45°C, an extraction pressure of 11 MPa, and a separation pressure of 8.5 MPa. It is speculated that the main reason for this is the difference between supercritical extraction and separation conditions and the chemical structure and physical properties of patchouli alcohol and patchouli ketone. However, based on the experimental results, enrichment can be achieved by selecting different supercritical extraction conditions.

[0109] As shown in Table 4, different stem-leaf ratios will significantly affect the oil extraction rate. From the experimental conclusion, pure patchouli leaves>50%>pure patchouli stems.

[0110] Table 5 shows that patchouli leaves have a positive impact on oil extraction and the content of patchouli alcohol. The order of patchouli alcohol is pure patchouli leaves > 50% stem-to-leaf ratio > pure patchouli stems. Patchouli stems contain a certain amount of patchouli alcohol, suggesting that their inclusion in patchouli oil production can save costs. However, under supercritical conditions, the percentage of patchouli alcohol was around 20% when using pure patchouli leaves and a 50% stem-to-leaf ratio. This may be due to two reasons: first, under these supercritical CO2 extraction conditions, the 20% patchouli alcohol vapor is saturated; second, supercritical CO2 has limited penetration into patchouli stem cells, which reside in the xylem and have denser cell walls than those in patchouli leaves.

[0111] It can be seen from Table 8 that the oil extraction rate is inversely proportional to the content of patchouli ketone, that is, the higher the proportion of patchouli stems, the lower the oil extraction rate. This indirectly shows that patchouli ketone mainly comes from patchouli stems, and the patchouli ketone content does not increase completely linearly under different stem-leaf ratios. It is speculated that this is similar to the change in patchouli alcohol content, which may be because supercritical carbon dioxide has limited penetration into patchouli stem tissue cells.

[0112] At the same time, different stem-leaf ratios also have an impact on acidity. As shown in Table 9, as the proportion of patchouli stems decreases, the acidity also decreases. Figure 1 As shown, it can be more clearly seen that the increase in acid value is directly proportional to the content of patchouli ketone and inversely proportional to the content of patchouli alcohol. Therefore, the acid value can be controlled by adjusting the proportion of patchouli stems.

[0113] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing patchouli oil, characterized in that: The following steps are involved: S1. The dried patchouli pieces are free of roots and impurities, and the patchouli leaves and stems are separated and pulverized and sieved to obtain patchouli leaf powder and patchouli stem powder; S2. The patchouli leaf powder and / or the patchouli stem powder obtained in step S1 are charged into a supercritical carbon dioxide extraction vessel and extracted for 2 hours. The volatile oil is collected from the separation port and the volatile oil is dehydrated to obtain patchouli oil.

2. The method for preparing patchouli oil according to claim 1, wherein: In the step S1, a No. 2 sieve is used for crushing and screening.

3. The method for preparing patchouli oil according to claim 1, wherein: In step S2, the mass ratio of the patchouli leaf powder obtained in step S1 to the patchouli stem powder obtained in step S1 is (0-1):(1-0).

4. The method for preparing patchouli oil according to claim 1, wherein: In step S2, the extraction temperature of the supercritical carbon dioxide extraction kettle is 40-50°C, the extraction pressure is 9-11 MPa, the separation pressure is 7.5-8.5 MPa, and the flow rate of carbon dioxide is 20 L / h.

5. Patchouli oil obtained according to the preparation method according to any one of claims 1 to 4.

Images