A plant essential oil deterpenoid process and its application

Abstract

This invention discloses a process for deterpening plant essential oils, comprising the following steps: mixing essential oils with an adsorbent, extracting with supercritical CO2, and obtaining deterpened plant essential oils after desorption of the adsorbent. This invention features a simple, feasible, and easily scalable process. The adsorbent can be reused multiple times, and the deterpening effect is significant. The adsorbent-supercritical CO2 deterpening method is a green process. After deterpening, the ginger essential oil retains its aroma and its appearance quality remains unchanged during room temperature and shade storage, with little risk of color darkening, turbidity, or layering. This facilitates further applications of ginger essential oil. This invention's technological route is also applicable to the deterpening process of other plant essential oils.

Description

Technical Field

[0001] This invention relates to a process for deterpene-refining plant essential oils and its application, and relates to C11B, specifically to the field of refined essential oils. Background Technology

[0002] With advancements in technology and improved living standards, the pursuit of natural ingredients has gradually increased. Plant-derived fragrances, medicines, and foods are becoming increasingly popular. Essential oils extracted from plants possess natural aromas and high value; however, they contain components that are difficult to preserve, easily oxidizing and deteriorating, thus affecting their shelf life. Research has found that terpenes in plant essential oils contribute little to their aroma and are poorly soluble in water and alcohol solutions, making them prone to oxidation and deterioration. Therefore, removing terpenes from plant essential oils can increase their stability and extend their shelf life. However, the properties of terpenes in plant essential oils are similar to those of the oxygen-containing compounds that produce aroma, making separation difficult. Therefore, developing a process for removing terpenes from plant essential oils is crucial.

[0003] Chinese invention patent CN202010220795.2 discloses a method for removing terpenes from essential oils. This method uses an organic salt associative extractant to form a eutectic solvent with oxygenated terpenes, achieving efficient extraction and separating most of the terpenes. Through two back-extraction processes, terpenes and oxygenated terpenes are completely separated, resulting in high purity and recovery rates of the obtained oxygenated terpenes. However, this extraction process requires a large amount of organic solvent, which may remain in the essential oil, affecting its quality. Chinese invention patent CN201610121908.7 discloses a method for extracting citrus essential oils that combines high-voltage pulsed electric field technology, ultrasonic extraction technology, and subcritical extraction technology. This method not only improves the leaching rate of active ingredients and effectively removes terpenes from citrus essential oils, but also leaves less pigment residue. However, this method requires the use of organic solvents such as sulfur hexafluoride or dimethyl ether, posing a high risk during processing and making it unsuitable for large-scale industrial applications. Summary of the Invention

[0004] To reduce the possibility of plant essential oils being oxidized and deteriorated, increase the stability of essential oils, and facilitate the storage of plant essential oils, the first aspect of the present invention provides a process for deterpene processing of plant essential oils, comprising the following steps:

[0005] (1) Mix the plant essential oil and adsorbent evenly and add them to the extraction vessel;

[0006] (2) Then extract under supercritical CO2. After extraction, remove the adsorbent from the extraction vessel.

[0007] (3) Add the desorbent to the adsorbent and sonicate to dissolve the plant essential oils adsorbed therein. Let it stand and separate into layers, and collect the supernatant.

[0008] (4) Repeat step 3 until the desorbent is colorless and transparent. Combine the supernatant and filter. Then perform rotary evaporation to obtain deterpene plant essential oil. Take samples for qualitative and quantitative analysis.

[0009] Ginger (Zingiber officinale Roscoe) essential oil is a volatile oily liquid with a distinctive aromatic odor. This aroma is contributed by oxygen-containing compounds, but ginger essential oil also contains a large amount of terpenes. Terpenes are insoluble in water and easily oxidized and decomposed, leading to increased relative density, viscosity, darkening of color, and loss of original flavor. Therefore, separating the terpenes from ginger essential oil can extend its shelf life. Existing methods for deterpening include distillation. However, the boiling points of terpenes and oxygen-containing compounds in ginger essential oil overlap within a certain range, preventing maximum separation. Furthermore, the high temperature of distillation can cause some heat-sensitive substances in the ginger essential oil to deteriorate. Solvent-based deterpening methods are also used, but solvents can easily remain in the ginger essential oil. Choosing a suitable solvent is crucial for good separation, but the solvent can negatively impact the quality of the ginger essential oil.

[0010] In a preferred embodiment, the adsorbent is selected from one or a combination of several of silica gel, alumina, macroporous resin, activated carbon, and molecular sieve.

[0011] In a preferred embodiment, the adsorbent is silica gel.

[0012] In a preferred embodiment, the weight ratio of the plant essential oil to the adsorbent is 10:(6-22).

[0013] In a preferred embodiment, the weight ratio of the plant essential oil to the adsorbent is 10:6.

[0014] The applicant discovered that a 10:6 ratio of ginger essential oil to silica gel allows terpenes and oxygen-containing substances to reach adsorption saturation in the silica gel, maximizing its adsorption and separation effect. Exceeding the preferred weight ratio prevents the components of ginger essential oil from being fully adsorbed by the silica gel, thus reducing the separation effect.

[0015] In a preferred embodiment, the extraction pressure of supercritical CO2 extraction in step 2 is 10-30 MPa.

[0016] In a preferred embodiment, the extraction pressure of supercritical CO2 extraction in step 2 is 20 MPa.

[0017] In a preferred embodiment, the extraction temperature of supercritical CO2 extraction in step 2 is 40-60℃.

[0018] In a preferred embodiment, the extraction temperature of supercritical CO2 extraction in step 2 is 55°C.

[0019] In a preferred embodiment, the carbon dioxide flow rate of supercritical CO2 extraction in step 2 is 200-1000 mL / min.

[0020] In a preferred embodiment, the carbon dioxide flow rate of supercritical CO2 extraction in step 2 is 600 mL / min.

[0021] In a preferred embodiment, the extraction time for supercritical CO2 extraction in step 2 is 30-70 min.

[0022] In a preferred embodiment, the extraction time for supercritical CO2 extraction in step 2 is 50 min.

[0023] The applicant further discovered that the extraction effect can be further optimized by controlling the extraction pressure, extraction temperature, CO2 flow rate, and extraction time of supercritical CO2 extraction. The reason may be that under the conditions of 20 MPa extraction pressure, 55℃ extraction temperature, 600 mL / min extraction flow rate, and 50 min extraction time, ginger essential oil adsorbed in silica gel can achieve sufficient mass transfer exchange with supercritical CO2, causing terpenoid compounds to desorb into the separation vessel, avoiding the desorption of oxygen-containing substances, achieving dissolution equilibrium, and achieving the best extraction effect.

[0024] In a preferred embodiment, the silicone is reused, and the number of times the silicone is reused is ≤4.

[0025] In a preferred embodiment, the desorbent is selected from one or a combination of several of anhydrous ethanol, acetone, propylene glycol, n-butanol, and methanol.

[0026] This application employs an adsorbent-supercritical CO2 extraction method for terpene removal, which offers advantages such as good naturalness, high extraction efficiency, preservation of functional activity, rapid mass transfer, low energy consumption, simple process, convenient operation, and no solvent residue. This application utilizes the difference in adsorption strength between terpenoid components and oxygen-containing compounds at polar SiOH sites and non-polar SiCH3 sites on silica gel to achieve separation. Oxygen-containing molecules in ginger essential oil contain non-polar portions, allowing them to adsorb at both polar and non-polar sites, while terpenoids are only adsorbed at non-polar sites with very weak adsorption. Using supercritical CO2 as the extractant, terpenoids and oxygen-containing compounds adsorbed on the adsorbent can be separated from the plant essential oil, achieving maximum separation.

[0027] The second aspect of the present invention provides an application of a process for deterpene processing of plant essential oils, which is applied to the deterpene processing of ginger essential oil, citrus essential oil, rose essential oil, rosemary essential oil, and clove essential oil.

[0028] In a preferred embodiment, the ginger essential oil is a ginger essential oil with a relative mass fraction of terpenoid compounds > 1%. The terpenoid compounds include, but are not limited to, β-phellandrene, γ-curcumene, α-curcumene, β-apigenin, hesperidin, gingerene, β-bisabolene, α-farnesene, and β-sesquiphellandrene, accounting for 67.39% of the relative mass fraction of the chemical composition of the ginger essential oil; the oxygen-containing compounds include, but are not limited to, gingerone, 6-gingerol, decanal, geraniol acetate, and α-citral, accounting for 15.99% of the relative mass fraction of the chemical composition of the ginger essential oil.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The plant essential oil deterpene process described in this invention adopts an adsorbent-supercritical CO2 extraction process, using silica gel as the adsorbent, which has a large adsorption capacity. Furthermore, the ratio of ginger essential oil to silica gel is 10:6, resulting in high adsorption and separation efficiency and high economic value.

[0031] (2) The plant essential oil deterpene process described in this invention uses extraction parameters of 20MPa extraction pressure, 55℃ extraction temperature, 600mL / min extraction flow rate, and 50min extraction time. It has the advantages of good naturalness, high extraction efficiency, no destruction of functional activity, fast mass transfer, low energy consumption, simple process, convenient operation, and no solvent residue.

[0032] (3) The deterpene process of plant essential oils described in this invention is simple, feasible, and easy to scale up. The adsorbent can be reused multiple times and the deterpene effect is obvious. The adsorbent-supercritical CO2 deterpene process is a green process. After deterpene treatment, ginger essential oil retains its aroma and its appearance quality will not change during room temperature and shade storage. It is difficult for the color to darken, become cloudy, or separate into layers, which is beneficial for the further application of ginger essential oil. The process route of this invention is also applicable to the deterpene process of other plant essential oils. Attached Figure Description

[0033] Figure 1 The image shows the GC-MS total ion chromatogram of ginger essential oil, the raw material in Example 1.

[0034] Figure 2 This is the GC-MS total ion chromatogram of the essential oil separated in Example 1;

[0035] Figure 3 The image shows the GC-MS total ion chromatogram of the essential oil extracted in Example 1.

[0036] In the diagram: 1. Decanal; 2. Gingerone; 3. 6-Gingerol. Detailed Implementation

[0037] Example 1

[0038] A method for deterpene processing of plant essential oils includes the following steps:

[0039] (1) Mix the plant essential oil and adsorbent evenly and add them to the extraction vessel;

[0040] (2) Then extract under supercritical CO2. After extraction, remove the adsorbent from the extraction vessel.

[0041] (3) The adsorbent was sonicated with anhydrous ethanol to dissolve the plant essential oil adsorbed therein, and the layers were allowed to stand and separate, and the supernatant was collected.

[0042] (4) Repeat step 3 until the anhydrous ethanol is colorless and transparent. Combine the supernatant and filter. Then perform rotary evaporation to obtain the deterpene plant essential oil. Take samples for qualitative and quantitative analysis.

[0043] The plant essential oil is ginger essential oil, which is homemade. The preparation method is as follows: wash the rhizomes of small yellow ginger produced in Shuicheng, Guizhou, slice them, dry them, grind them into powder, and then prepare them by supercritical CO2 extraction.

[0044] The adsorbent is silica gel, purchased from Qingdao Spectrum Separation Materials Co., Ltd., with a mesh size of 100-200. The weight ratio of ginger essential oil to silica gel is 10g:6g.

[0045] In step 2, the extraction pressure is 20 MPa, the extraction temperature is 55℃, the extraction flow rate is 600 mL / min, and the extraction time is 50 min.

[0046] The adsorbent, after the essential oil has been completely dissolved, is dried at 70°C until the moisture content is less than 2%, and then the adsorbent is recovered.

[0047] The terpene-rich plant essential oil, after supercritical CO2 extraction in step 2, is desorbed into a separation vessel, becoming the separation vessel essential oil; the plant essential oil processed in step 4 is the extraction vessel essential oil. In Example 1, the raw material ginger essential oil weighed 10.022g, with a terpene compound content of 67.39% and an oxygen-containing compound content of 15.99%; the separation vessel essential oil weighed 7.251g, with a terpene compound content of 75.05% and an oxygen-containing compound content of 10.33%; and the extraction vessel essential oil weighed 2.00g, with a terpene compound content of 1.44% and an oxygen-containing compound content of 72.91%.

[0048] Note: The essential oils in the extraction vessel contain some silica gel impurities during the separation process, and the quality test of the essential oils has a certain margin of error.

[0049] The GC-MS total ion chromatogram of raw ginger essential oil is shown below. Figure 1 The GC-MS total ion chromatogram of the essential oil from the separation vessel is shown below. Figure 2 The GC-MS total ion chromatogram of the essential oil from the extraction vessel is shown below. Figure 3 .

[0050] Example 2

[0051] A process for deterpene-removing plant essential oils, with the same steps as in Example 1, except that the weight ratio of ginger essential oil to silica gel is 10g:10g.

[0052] In step 2, the extraction pressure is 15 MPa, the extraction temperature is 50℃, the extraction flow rate is 600 mL / min, and the extraction time is 50 min.

[0053] Example 3

[0054] A process for deterpene-removing plant essential oils, with the same steps as in Example 1, except that the weight ratio of ginger essential oil to silica gel is 10g:6g.

[0055] In step 2, the extraction pressure is 15 MPa, the extraction temperature is 55℃, the extraction flow rate is 600 mL / min, and the extraction time is 50 min.

[0056] Example 4

[0057] A process for deterpene-removing plant essential oils, with the same steps as in Example 1, except that the weight ratio of ginger essential oil to silica gel is 10g:10g.

[0058] In step 2, the extraction pressure is 15 MPa, the extraction temperature is 55℃, the extraction flow rate is 400 mL / min, and the extraction time is 50 min.

[0059] Example 5

[0060] A process for deterpene-removing plant essential oils, with the same steps as in Example 1, except that the weight ratio of ginger essential oil to silica gel is 10g:10g.

[0061] In step 2, the extraction pressure is 15 MPa, the extraction temperature is 55℃, the extraction flow rate is 600 mL / min, and the extraction time is 40 min.

[0062] Example 6

[0063] A process for deterpene-removing plant essential oils, with specific steps similar to Example 1, but differing in that: step 2 involves three stages of extraction; the first stage extraction pressure is 10 MPa, the extraction temperature is 40°C, the extraction flow rate is 400 mL / min, and the extraction time is 30 min; the second stage extraction pressure is 16 MPa, the extraction temperature is 40°C, the extraction flow rate is 400 mL / min, and the extraction time is 10 min; the third stage extraction pressure is 25 MPa, the extraction temperature is 60°C, the extraction flow rate is 800 mL / min, and the extraction time is 30 min.

[0064] Example 7

[0065] A process for deterpening plant essential oils, with the same steps as in Example 6, except that the adsorbent is alumina, purchased from Tianjin Kemio Chemical Reagent Co., Ltd., and is of analytical grade.

[0066] Example 8

[0067] A process for deterpene-removing plant essential oils, with the same steps as in Example 6, except that the adsorbent is a macroporous resin purchased from Qingdao Spectrum Separation Materials Co., Ltd., model HPD-100.

[0068] Example 9

[0069] A process for deterpening plant essential oils, with the same steps as in Example 1, except that the adsorbent is silica gel that has undergone one adsorption and desorption process.

[0070] Example 10

[0071] A process for deterpening plant essential oils, with the same steps as in Example 1, except that the adsorbent is silica gel that has undergone two adsorption and desorption processes.

[0072] Example 11

[0073] A process for deterpening plant essential oils, with the same steps as in Example 1, except that the adsorbent is silica gel that has undergone three adsorption and desorption processes.

[0074] Performance testing

[0075] The plant essential oil deterpene removal process described in this application involves the following steps: After supercritical CO2 extraction in step 2, the terpene-rich plant essential oil is desorbed into a separation vessel to obtain the separation vessel essential oil; the plant essential oil processed in step 4 is the extraction vessel essential oil. Gas chromatography-mass spectrometry (GC-MS) is used for qualitative and quantitative detection of terpene compounds and oxygen-containing compounds in the plant essential oil.

[0076] The quantitative test results of the plant essential oils obtained by the deterpene processes in Examples 6, 7, and 8 are shown in Table 1.

[0077] Table 1

[0078]

[0079] As shown in Table 1, when the adsorbent dissolves ginger essential oil, silica gel and alumina have basically the same deterpene removal effect and are both higher than macroporous resin. Considering the oil absorption capacity and economic factors, silica gel with a larger adsorption capacity is selected as the adsorbent.

[0080] The adsorbent-supercritical CO2 extraction method, which employs staged extraction and desorption, does not show a significant difference in the separation effect of terpenes in the essential oil at each stage of the separation vessel. In the subsequent stages of this study, the experimental process research will adopt the adsorbent-supercritical CO2 extraction method with primary desorption and silica gel as the adsorbent.

[0081] The quantitative test results of the plant essential oils obtained from the extraction vessel by the deterpene process in Examples 1, 9, 10, and 11 are shown in Table 2.

[0082] Table 2 Terpenoids / % Oxygenated Compounds / %

[0083]

[0084]

[0085] According to the results in Table 2, silica gel can be reused at least 4 times and has no effect on the adsorption and deterpene removal of ginger essential oil.

[0086] The quantitative test results of the plant essential oils obtained from the extraction vessel through the deterpene removal processes of Examples 1, 2, 3, 4, and 5 are shown in Table 3.

[0087] Table 3

[0088] Terpenes / % Oxygen-containing compounds / % Example 1 1.44 72.91 Example 2 4.52 68.05 Example 3 2.39 72.02 Example 4 11.32 60.38 Example 5 14.61 55.92

Claims

1. A method for deterpene processing of plant essential oils, characterized in that, The following steps are involved: (1) Mix the plant essential oil and adsorbent evenly and add them to the extraction vessel; (2) Then extract under supercritical CO2. After extraction, remove the adsorbent from the extraction vessel. (3) Add the desorbent to the adsorbent and sonicate to dissolve the plant essential oils adsorbed therein. Let it stand and separate into layers, and collect the supernatant. (4) Repeat step 3 until the desorbent is colorless and transparent. Combine the supernatant and filter. Then perform rotary evaporation to obtain deterpene plant essential oil. Take samples for qualitative and quantitative analysis. The adsorbent is silica gel; the weight ratio of the plant essential oil to the adsorbent is 10:(6-22); The extraction pressure of supercritical CO2 extraction in step 2 is 10-30 MPa; the extraction temperature of supercritical CO2 extraction in step 2 is 40-60℃; the carbon dioxide flow rate of supercritical CO2 extraction in step 2 is 200-1000 mL / min; and the extraction time of supercritical CO2 extraction in step 2 is 30-70 min.

2. The deterpene removal process for plant essential oils according to claim 1, characterized in that, The silicone is reusable, and the number of times the silicone can be reused is ≤4.

3. The deterpene removal process for plant essential oils according to claim 1, characterized in that, The desorbent is selected from one or a combination of several of anhydrous ethanol, acetone, propylene glycol, n-butanol, and methanol.

4. The application of a deterpene-removing process for plant essential oils according to any one of claims 1-3, characterized in that, It is used in the deterpene treatment of ginger essential oil, citrus essential oil, rose essential oil, rosemary essential oil, and clove essential oil.

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