Process for solvent-free microwave extraction of pine needle volatile oil through liquid nitrogen quick-freezing treatment

Abstract

The invention discloses a liquid nitrogen quick-freezing treatment solvent-free microwave extraction process for pine needle volatile oil, which comprises the following steps: (1) soaking complete pine needle leaves in liquid nitrogen for freezing treatment for 5 minutes; (2) putting the liquid nitrogen subjected to freezing treatment in the step (1) into a crusher, and crushing into powder; (3) putting the powder in the step (2) into a container, and transferring the container into a microwave device for solvent-free microwave extraction; and (4) collecting volatile oil components at the upper half part of the light oil extractor after the extraction is completed, and adding anhydrous sodium sulfate to remove residual water. According to the liquid nitrogen quick-freezing treatment solvent-free microwave extraction process for pine needle volatile oil, cell walls of pine needles are seriously destroyed through liquid nitrogen freezing, then microwave extraction and microwave are used for further destroying the cell walls, and the dissolution rate of volatile oil in pine needle cells is increased by controlling the microwave power and the extraction time; the pine needle volatile oil with more chemical components can be obtained, and simple and efficient extraction of the pine needle volatile oil is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of volatile oil extraction, and in particular to a process for extracting pine needle volatile oil by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment. Background Art

[0002] Pine trees are gymnosperms of the genus Pinus in the family Pinaceae, distributed throughout China, especially in large quantities in the three northeastern provinces. Pine needles regenerate quickly, with seasonal harvests every year and wide applications. Pine needles are the needle-shaped leaves of pine trees and can be used as a continuously utilizable natural plant resource. Pine needle volatile oil is a chemical substance extracted from pine needles, which has poor water solubility, an aromatic odor, and is volatile. It contains a high content of active ingredients. The sterols in pine needle volatile oil have antioxidant properties and can prevent arteriosclerosis and hyperlipidemia; the vitamins in it are important vitamins in humans and animals, with strong antioxidant properties, being important antioxidants in the body and capable of regulating endocrine disorders; the flavonoid compounds in pine needle volatile oil also have strong antibacterial activities, having antibacterial effects and inhibiting the growth of various fungi and bacteria.

[0003] The main methods for extracting pine needle volatile oil include steam distillation, compound solvent extraction, supercritical CO2 extraction, microwave distillation, etc. Steam distillation for extracting volatile oil is a commonly used method by domestic and foreign manufacturers at present due to its simple equipment and low cost. However, steam distillation is difficult to break plant cell walls, resulting in a low extraction rate of volatile oil. Liquid nitrogen freezing of plant cells is a commonly used method to break plant cell walls. After liquid nitrogen freezing and crushing, plant cell walls can be better broken. Coupled with the cell wall damage caused by microwave irradiation, plant cell walls can be broken more efficiently and thoroughly, increasing the extraction efficiency of volatile oil. Solvent-free microwave extraction can shorten the extraction time, reduce energy consumption, have a higher oil extraction rate, be green and environmentally friendly, do not require the addition of any organic solvents, can focus on extracting a certain component in the volatile oil by changing the power, and can well preserve the natural active ingredients in the volatile oil without being damaged. Moreover, after liquid nitrogen freezing, the pine needles are broken into powder without causing the outflow of internal moisture, so that the volatile components are better preserved in the raw materials, which is beneficial to extraction. Summary of the Invention

[0004] The purpose of the present invention is to provide a process for extracting pine needle volatile oil by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment. Through liquid nitrogen freezing, the pine needle cell walls are severely damaged, and then microwave extraction is used. The microwave further damages the cell walls. By controlling the microwave power and extraction time, the dissolution rate of volatile oil in pine needle cells is increased, and more chemically component-rich pine needle volatile oil can be obtained, realizing the simple and efficient extraction of pine needle volatile oil.

[0005] To achieve the above purpose, the present invention provides a process for extracting pine needle volatile oil by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment, including the following steps:

[0006] (1) Pretreatment of raw materials: Immerse the intact pine needles in liquid nitrogen for freezing treatment for 5 minutes.

[0007] (2) Put the liquid nitrogen after the freezing treatment in step (1) into a crusher and break it into powder.

[0008] (3) Put the powder in step (2) into a container and transfer it into a microwave device for solvent-free microwave extraction.

[0009] (4) After the extraction is completed, collect the volatile oil components in the upper part of the light oil extractor and add anhydrous sodium sulfate to remove the residual moisture.

[0010] Preferably, in step (3), the power range of the microwave device is 252W - 700W.

[0011] Preferably, in step (3), the microwave extraction time is 20min - 60min.

[0012] Preferably, in step (3), the power of the microwave device is 567W.

[0013] Preferably, in step (3), the microwave extraction time is 30min.

[0014] The advantages and positive effects of the process for solvent-free microwave extraction of pine needle volatile oil by liquid nitrogen quick-freezing treatment described in the present invention are as follows:

[0015] 1. The present invention uses the solvent-free microwave extraction method to extract pine needle volatile oil. Microwave irradiation severely damages the cell structure of pine needles, and microwave heats the water inside pine needle cells, bringing out the pine needle volatile oil, improving the dissolution rate of volatile oil in pine needle cells, and greatly shortening the extraction time. The highest extraction rate of pine needle volatile oil can reach 0.605%, the extraction rate of volatile oil is relatively high, the operation is simple, and it is green and efficient.

[0016] 2. The present invention uses the pre-treatment method of freezing pine needles with liquid nitrogen to further help break the cell wall, improve the extraction efficiency. The pine needle volatile oil extracted by the solvent-free microwave method is analyzed and identified by GC-MS, and there are various chemical components and rich components.

[0017] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0018] Figure 1 It is the total ion current chromatogram of GC-MS of pine needle volatile oil in Example 1 of the present invention;

[0019] Figure 2 It is the influence of microwave power on the extraction rate in Examples 1 - 7 of the present invention;

[0020] Figure 3 For the influence of extraction time on the extraction rate in Examples 1 - 7 of the present invention;

[0021] Figure 4 It is the total ion current chromatogram of GC - MS of the pine needle volatile oil extracted by steam distillation in the verification example of the present invention;

[0022] Figure 5 It is the total ion current chromatogram of GC - MS of the pine needle volatile oil extracted by ordinary solvent - free extraction in the verification example of the present invention;

[0023] Figure 6 It is the total ion current chromatogram of GC - MS of the pine needle volatile oil extracted by solvent - free microwave extraction with liquid nitrogen quick - freezing treatment in the verification example of the present invention. Detailed implementation mode

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and examples.

[0025] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs.

[0026] Example 1

[0027] The pine needles after liquid nitrogen freezing are crushed into powder, placed in a microwave oven, the microwave power is adjusted to 252W, and the extraction time is 30 min to obtain the pine needle volatile oil. The extraction rate of the volatile oil is calculated to be 3 mL / kg.

[0028] The obtained pine needle volatile oil is subjected to GC - MS detection. The gas chromatography conditions are as follows: capillary quartz chromatographic column (0.25 mm × 0.25 μm, length 30 m), the vaporization chamber and injection temperature are set at 230 °C and 280 °C respectively; temperature - rising program: first maintain at 60 °C for 5 min, then increase from 60 °C to 120 °C at a rate of 10 °C / min and hold for 5 min, then increase from 120 °C to 200 °C at the same temperature - rising rate and maintain for 5 min, and then increase from 200 °C to 280 °C at the same rate and maintain for 15 min; the carrier gas is high - purity helium, the flow rate is 1.0 mL / min; the injection volume is 1 μL; the split ratio is 1:2.

[0029] Mass spectrometry conditions: electron impact (EI) ion source; electron energy is 70 eV; the scanning range is 15 - 500 amu.

[0030] The chemical components and relative mass fractions of the pine needle volatile oil are shown in Table 1. The total ion current of the GC - MS of the pine needle volatile oil is as Figure 1 shown.

[0031] Table 1

[0032] Serial number Compound Retention time / min Chemical formula CAS Relative content % 1 3-Carene 6.48 <![CDATA[C 10 H 16 > 13466-78-9 6.51％ 2 Camphene 6.86 <![CDATA[C 10 H 16 > 79-92-5 1.23％ 3 Sabinene 7.56 <![CDATA[C 10 H 16 > 3387-41-5 0.44％ 4 Myrcene 7.92 <![CDATA[C 10 H 16 > 123-35-3 1.07％ 5 Phellandrene 8.22 <![CDATA[C 10 H 16 > 99-83-2 0.15％ 6 1,3,3-Trimethyltricyclo[2.2.1.0(26)]heptane 8.36 <![CDATA[C 10 H 16 > 488-97-1 0.93％ 7 D-Limonene 8.79 <![CDATA[C 10 H 16 > 5989-27-5 2.97％ 8 α-Terpinene 10.05 <![CDATA[C 10 H 16 > 99-86-5 6.35％ 9 Bornyl formate 14.45 <![CDATA[C 11 H 18 O2]]> 7492-41-3 6.67％ 10 Ocimene 16.13 <![CDATA[C 10 H 16 > 13877-91-3 0.12％ 11 α-Cubebene 16.56 <![CDATA[C 15 H 24 > 17699-14-8 0.41％ 12 Sesquithujene 17.26 <![CDATA[C 15 H 24 > 58319-06-5 0.11％ 13 Ylangene 17.39 <![CDATA[C 15 H 24 > 14912-44-8 0.40％ 15 1-Caryophyllene 18.63 <![CDATA[C 15 H 24 > 87-44-5 23.24％ 16 β-Cubebene 18.78 <![CDATA[C 15 H 24 > 13744-15-5 0.52％ 17 Sesquiphellandrene 19.16 <![CDATA[C 15 H 24 > 54324-03-7 0.19％ 18 α-Caryophyllene 19.335 <![CDATA[C 15 H 24 > 6753-98-6 1.75％ 19 Cis-Muurola-4(15),5-diene 19.52 <![CDATA[C 15 H 24 > 157477-72-0 0.54％ 20 γ-Muurolene 19.83 <![CDATA[C 15 H 24 > 30021-74-0 3.33％ 21 Germacrene 19.95 <![CDATA[C 15 H 24 > 23986-74-5 14.51％ 22 Sesquiphellandrene 20.15 <![CDATA[C 15 H 24 > 54324-03-7 1.08％ 23 Tetramethylbicycloundecadiene 20.21 <![CDATA[C 15 H 24 > 24703-35-3 2.14％ 24 α-Muurolene 20.25 <![CDATA[C 15 H 24 > 10208-80-7 1.19％ 25 γ-Cadinene 20.54 <![CDATA[C 15 H 24 > 39029-41-9 4.74％ 26 δ-Muurolene 20.71 <![CDATA[C 15 H 24 > 16729-01-4 13.98％ 27 Cubane 20.84 <![CDATA[C 15 H 24 > 29837-12-5 0.44％ 28 β-Bourbonene 21.56 <![CDATA[C 15 H 24 > 5208-59-3 0.13％ 29 2,5-Dimethyl-6-methylene spiro[2.4]heptane 22.56 <![CDATA[C 10 H 16 > 62238-24-8 0.47％ 30 1,8,11,14-Heptadecatetraene 22.75 <![CDATA[C 17 H 28 > 10482-53-8 0.94％ 31 1,3-Bis-(2-cyclopropyl,2-methylcyclopropyl)-but-2-en-1-one 26.68 <![CDATA[C 18 H 26 O]]> 1000222-08-6 0.23％ Total - - - - 96.9％

[0033] Example 2

[0034] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 406 W and the extraction time is 30 min. The extraction rate of volatile oil is 4.2 mL / kg.

[0035] Example 3

[0036] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 567 W and the extraction time is 30 min. The extraction rate of volatile oil is 6 mL / kg.

[0037] Example 4

[0038] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 700 W and the extraction time is 30 min. The extraction rate of volatile oil is 5 mL / kg.

[0039] Example 5

[0040] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 567 W and the extraction time is 20 min. The extraction rate of volatile oil is 5.1 mL / kg.

[0041] Example 6

[0042] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 567 W and the extraction time is 40 min. The extraction rate of volatile oil is 6 mL / kg.

[0043] Example 7

[0044] The same parts as in Example 1 will not be described in detail. The differences are that the microwave power is 567 W and the extraction time is 60 min. The extraction rate of volatile oil is 6 mL / kg.

[0045] Comparative Example 1

[0046] The same parts as in Example 3 will not be described in detail. The differences are that the pine needles were not treated by liquid nitrogen freezing. The extraction rate of volatile oil is 5 mL / kg.

[0047] From Example 3 and Comparative Example 1, it can be seen that the extraction rate of liquid nitrogen freezing and crushing into powder is higher than that of direct solvent-free microwave extraction.

[0048] As Figure 2 and 3 shown, from Examples 1-7, it can be seen that when the microwave heating power is 567 W and the microwave heating time is 30 min, the yield of volatile oil obtained is the highest.

[0049] Verification Example

[0050] (1) Steam distillation for extracting volatile oil from pine needles

[0051] Take 100 g of pine needles, cut them into 1-cm small pieces, add 500 mL of water, and heat for steam distillation for 3 h. The extraction rate is 4.7 mL / kg. The chemical components of the volatile oil from pine needles are shown in Table 2. The total ion current of the GC-MS of the volatile oil from pine needles is as Figure 4 shown.

[0052] Table 2

[0053]

[0054]

[0055] (2) Ordinary solvent-free extraction of volatile oil from pine needles

[0056] Cut 100 g of pine needles into 1-cm small pieces, directly put them into a flask without adding any solvent, and extract without microwave heating. The microwave power is 406 W, and the extraction time is 30 min. The extraction rate is 5 mL / kg. The chemical components of the volatile oil from pine needles are shown in Table 3. The total ion current of the GC-MS of the volatile oil from pine needles is as Figure 5 shown.

[0057] Table 3

[0058]

[0059]

[0060] (3) Solvent-free microwave extraction of volatile oil from pine needles after liquid nitrogen quick-freezing treatment

[0061] Immerse 100 g of intact pine needles in liquid nitrogen for freezing treatment for 5 min; put the frozen liquid nitrogen into a crusher and break it into powder; put the powder into a container and transfer it into a microwave device for solvent-free microwave extraction. The microwave power is 567 W, and the extraction time is 30 min; after extraction, collect the volatile oil components in the upper part of the light oil extractor, and add anhydrous sodium sulfate to remove the residual moisture. The extraction rate is 6 mL / kg. The chemical components of the volatile oil from pine needles are shown in Table 4. The total ion current of the GC-MS of the volatile oil from pine needles is as Figure 6 shown.

[0062] Table 4

[0063]

[0064]

[0065] By comparing the above three methods for extracting volatile oil from pine needles, the solvent-free microwave extraction of volatile oil from pine needles after liquid nitrogen quick-freezing treatment has the highest extraction rate.

[0066] There are certain differences in the types of compounds contained in the pine needle volatile oils obtained by three extraction methods identified by GC-MS, but the main components are roughly the same. The proportion of oxygen-containing compounds in the volatile oil components extracted by the solvent-free microwave method and the solvent-free microwave method after liquid nitrogen quick-freezing is relatively high. This may be because oxygen-containing compounds have a larger dipole, so under the irradiation of microwaves, their interaction is more intense than that of sesquiterpene hydrocarbons with low dipole. Therefore, they can be more completely extracted from plant materials. At the same time, oxygen-containing compounds have a significant fragrance, so they are more valuable than sesquiterpene hydrocarbons.

[0067] Therefore, the present invention adopts the above-mentioned process of solvent-free microwave extraction of pine needle volatile oil with liquid nitrogen quick-freezing treatment. By liquid nitrogen freezing, the cell walls of pine needles are severely damaged, and then microwave extraction is used. The microwave further damages the cell walls. By controlling the microwave power and extraction time, the dissolution rate of volatile oil in pine needle cells is increased, and more chemically component-rich pine needle volatile oil can be obtained, realizing the simple and efficient extraction of pine needle volatile oil.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for extracting volatile oil from pine needles by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment, characterized in that, It includes the following steps: (1) Raw material pretreatment: Immerse the whole pine needles in liquid nitrogen for freezing treatment for 5 minutes; (2) Put the liquid nitrogen after the freezing treatment in step (1) into a crusher and break it into powder; (3) Put the powder in step (2) into a container and transfer it to a microwave device for solvent-free microwave extraction; (4) After the extraction is completed, collect the volatile oil components in the upper part of the light oil extractor and add anhydrous sodium sulfate to remove the residual moisture.

2. The process for extracting volatile oil from pine needles by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment according to claim 1, wherein: In step (3), the power range of the microwave device is 252W - 700W.

3. The process for extracting volatile oil from pine needles by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment according to claim 1, wherein: In step (3), the microwave extraction time is 20min - 60min.

4. A process for extracting volatile oil from pine needles by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment according to claim 2, characterized in that: In step (3), the power of the microwave device is 567W.

5. A process for extracting volatile oil from pine needles by solvent-free microwave extraction with liquid nitrogen quick-freezing treatment according to claim 3, characterized in that: In step (3), the microwave extraction time is 30min.

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