A method for extracting tobacco aroma raw materials using ionic liquid as extractant

Abstract

The present invention discloses a method for extracting tobacco aroma raw materials using an ionic liquid as an extractant. The method comprises: crushing and sieving the tobacco raw materials to obtain tobacco dust; mixing the tobacco dust with an ionic liquid at a predetermined mass ratio, sealing the mixture, extracting the tobacco dust with the ionic liquid, cooling the mixture to room temperature, and then stripping the mixture with an organic solvent. The tobacco dust and the organic solvent are then centrifuged to separate, the supernatant is collected, and the organic solvent is removed by vacuum distillation to obtain the tobacco aroma raw material. The ionic liquid is composed of cations and anions, wherein the cation is selected from at least one of unsubstituted or substituted imidazolium cations, pyridinium cations, choline cations, piperidinium cations, pyrrolidinium cations, and choline cations. Using the ionic liquid as an extractant, the extractant has a high extraction capacity for aroma-causing substances and is recyclable, thereby reducing production costs. Using an organic solvent stripping method followed by combining and concentrating the mixture allows for comprehensive extraction of components with a wide range of polarities from the ionic liquid and tobacco dust.

Description

Technical Field

[0001] The invention belongs to the technical field of tobacco aroma raw materials and relates to a method for extracting tobacco aroma raw materials by using ionic liquid as an extractant. Background Art

[0002] Tobacco flavors and fragrances are essential raw materials in tobacco production, and extracting flavor compounds from tobacco leaves is the primary method for obtaining these ingredients. Tobacco extracts, made from tobacco leaves, not only enhance tobacco's characteristic aroma and bring out its inherent flavor, but also offer increased safety, exempt from the list of tobacco additives. With the increasing development of emerging tobacco products like heat-not-burn (HNB) tobacco, market demand for tobacco extracts is increasing.

[0003] The aroma substances in tobacco can be divided into two categories: one is compounds with a certain fragrance, including terpenoid aromatic compounds, nitrogen-containing compounds such as alkaloids, oxygen-containing compounds such as organic acids, etc., and the other is potential aroma substances such as carotenoids, cypermethrin compounds and lysine compounds, which have no fragrance themselves and produce small-molecule aroma substances upon high-temperature decomposition. The tobacco leaf extraction method and medium are the key to determining the composition of the aroma raw materials and the extraction efficiency. The most common extraction methods currently include steam distillation, solvent extraction, supercritical CO2 extraction, simultaneous distillation-extraction, etc., and the commonly used extraction media are concentrated in water, CO2 and a few organic solvents. The adjustable range of physicochemical properties is very limited, making it difficult to have high solubility for the aroma components of different structures in tobacco at the same time, and the ability to dissolve substances through the cell wall is weak, resulting in a generally low yield of effective ingredients, or even inability to dissolve, which seriously limits the extraction efficiency. Ultrasonic-assisted extraction (CN104138028B) only accelerates the extraction rate and has no effect on solubility.

[0004] Therefore, there is an urgent need to develop efficient extraction media and extraction methods for tobacco aroma raw materials. Summary of the Invention

[0005] Ionic liquids generally refer to compounds composed of anions and cations that are liquid at or near room temperature. Compared to molecular solvents, their unique structure gives them unique properties such as low volatility, low melting point, high cohesive energy, and non-flammability. Furthermore, the properties of ionic liquids can be adjusted by varying the anion and cation structure. They can interact with solutes through multiple interactions, such as electrostatics, hydrogen bonding, and π-π interactions, resulting in superior solubility for complex molecules compared to conventional organic solvents. More importantly, some ionic liquids can dissolve cellulose (the main component of cell walls) and disrupt the cell wall, allowing target components to be released through the cell wall and improving extraction efficiency. These properties make ionic liquids suitable as novel extraction media for extracting aromatic raw materials from tobacco.

[0006] Objective: To overcome the deficiencies in the prior art, the present invention provides a method for extracting tobacco aroma raw materials using ionic liquid as an extractant, and a method for extracting aroma components from tobacco and preparing aroma raw materials using ionic liquid as an extractant.

[0007] Compared with the existing extraction methods, the present invention has the advantages of high extraction efficiency, simple operation, easy scale-up, etc., and is suitable for industrial production.

[0008] Technical solution: The preferred technical solution adopted by the present invention is:

[0009] According to a first aspect of the present invention, there is provided a method for extracting tobacco aroma raw materials using an ionic liquid as an extractant, comprising:

[0010] S1: crushing and sieving tobacco raw materials to obtain tobacco powder;

[0011] S2: Mixing tobacco dust and ionic liquid in a set mass ratio, sealing, extracting the tobacco dust with ionic liquid, cooling to room temperature, and then back-extracting with an organic solvent. Centrifugally separate the tobacco dust and the organic solvent, collect the supernatant, and remove the organic solvent by vacuum distillation to obtain tobacco aroma raw materials.

[0012] In some embodiments, in step S1, the tobacco raw material is one or a mixture of flue-cured tobacco, burley tobacco, oriental tobacco, sun-cured tobacco, Maryland tobacco, and cigar tobacco.

[0013] In some embodiments, the ionic liquid is composed of a cation and an anion, wherein the cation is selected from at least one of an unsubstituted or substituted imidazolium cation, a pyridinium cation, a choline cation, a piperidinium cation, a pyrrolidinium cation, and a choline cation.

[0014] Furthermore, the cation or one or more substituents, each of which is independently selected from a C1-C10 alkyl group, a C2-C6 alkenyl group, a C6-C12 aryl group, a hydroxyl group, a hydroxyethyl group, an amino group, a carboxyl group and a carbonyl group.

[0015] In some embodiments, the anion is selected from at least one of amino acid, chloride, bromide, iodide, tetrafluoroborate, trifluoromethanesulfonate, sulfate, bisulfate, nitrate, and acetate.

[0016] In some embodiments, the ionic liquid is selected from one or more of 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, and choline glycinate.

[0017] In some embodiments, the mass ratio of the tobacco dust to the ionic liquid is 1:(2-10), preferably 1:(2-4).

[0018] In some embodiments, the ionic liquid extraction time is 0.5-24 hours, and the extraction temperature is 20-90°C. Preferably, the extraction time is 2-6 hours, and the extraction temperature is 40-70°C.

[0019] In some embodiments, the organic solvent used for back extraction includes at least one of normal or isomeric alkanes with a carbon number of 6-10, chloroform, dichloromethane or chloroform, ether, methyl tert-butyl ether, petroleum ethers of different boiling points, C3-C10 ester solvents, and C4-C10 alcohol solvents; wherein the C3-C10 ester solvents include methyl acetate, ethyl acetate, and butyl acetate; and the C4-C10 alcohol solvents include n-butanol, n-hexanol, and 2-hexanol.

[0020] The organic solvent used in the stripping is one or more of n-hexane, n-octane, ether, methyl tert-butyl ether, dichloromethane, chloroform and ethyl acetate.

[0021] More preferably, the organic solvent used in the stripping is a combination of three solvents of different polarities, such as n-hexane, dichloromethane, and methyl tert-butyl ether.

[0022] According to a second aspect of the present invention, there is provided a tobacco aroma raw material, which is prepared by the method described in the first aspect.

[0023] The aroma components in tobacco are complex and difficult to extract. This invention uses ionic liquids as extraction media, which have strong solubility and cell wall-breaking capabilities for complex structures. The anionic and cationic structures and strong hydrogen bond alkalinity of ionic liquids enable strong interactions and high solubility for substances such as terpenes, alkaloids, organic acids, and alcohols. Some ionic liquids can dissolve cellulose and have cell wall-breaking capabilities, thereby improving the extraction efficiency of aroma components.

[0024] Beneficial effects: The method of the present invention for extracting tobacco aroma raw materials using ionic liquid as an extractant has the following advantages:

[0025] (1) The present invention uses ionic liquid as an extractant, which has a high extraction capacity for aroma substances and can be recycled, thereby reducing production costs;

[0026] (2) The present invention adopts a method of combining and concentrating organic solvents with different polarities after stripping, which can comprehensively extract components with a wide range of polarity in ionic liquids and cigarette dust.

[0027] (3) The present invention optimizes the extraction-stripping process, and the obtained aroma raw materials contain more than 100 aroma-causing components of varying contents, such as organic acids, nicotine, terpenes, and carotenoids. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the results of analyzing the components in the fragrance raw materials using gas chromatography-mass spectrometry (GC-MS) in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the embodiments.

[0030] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0031] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, percentages or ratios and other numerical values ​​used in this specification and the appended claims are to be understood as being modified in all instances by the term "about." In addition, all ranges disclosed herein are inclusive and independently combinable.

[0032] In the following examples of the present invention, gas chromatography-mass spectrometry (GC-MS) was used to analyze the components in the fragrance raw materials. The specific conditions of GC-MS were: DB-5MS (60m*1.0μm*0.25mm); programmed temperature: the initial temperature was 60°C, and the temperature was increased to 250°C at 2°C / min, then increased to 290°C at 5°C / min, and maintained for 20 minutes; injection volume: 1μL; split ratio: 10:1; injection port temperature: 290°C; carrier gas: He, flow rate: 1.5mL / min; transmission line temperature: 290°C; ionization mode: EI; ion source temperature: 230°C; ionization energy: 70eV; quadrupole temperature: 150°C; mass spectrometry mass scanning range: 26-1000amu.

[0033] Example 1

[0034] Tongxiang sun-cured tobacco is dried at 60°C for 30 minutes, then crushed and passed through a 60-mesh sieve. The tobacco dust is then mixed with 1-ethyl-3-methylimidazolium acetate ([EMIm]OAc) ionic liquid in a 1:2 mass ratio, sealed, and extracted with n-hexane, dichloromethane, and methyl tert-butyl ether (MTBE) in a 1:2 mass ratio. The mixture is then centrifuged to separate the tobacco dust and the organic solvent. The supernatants are then combined and the organic solvent removed by vacuum distillation to yield a black, paste-like aroma raw material containing 10 esters, including geranylacetone, furfural, neophytadiene, megastigmatrienone, 2-hydroxy-γ-butyrolactone, and nicotine, as well as five alcohols, six monocyclic compounds, and other components.

[0035] Example 2

[0036] Burley tobacco was dried at 60°C for 30 minutes, then crushed and passed through a 40-mesh sieve. The tobacco dust was mixed with 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) ionic liquid at a mass ratio of 1:3, sealed, and extracted with stirring at 70°C for 4 hours before cooling to room temperature. The tobacco dust was then stripped with n-hexane, dichloromethane, methyl tert-butyl ether, and ethyl acetate in a 1:1.5 mass ratio. After stripping with each solvent, the tobacco dust and organic solvent were separated by centrifugation. The supernatants were collected, combined, and the organic solvent removed by vacuum distillation. The aroma raw material was dissolved in twice the mass of ethanol, and the ethanol and residual ethyl acetate were removed by vacuum distillation. This process was repeated twice to obtain a black paste of aroma raw material. The main components identified were 13 alcohols, 11 esters, and 21 nitrogen heterocycles.

[0037] Example 3

[0038] The flue-cured tobacco was dried at 60°C for 30 minutes, then crushed and passed through a 60-mesh sieve. The tobacco dust was mixed with 1-butyl-3-methylimidazolium chloride ([BMIm]Cl) ionic liquid in a 1:4 mass ratio, sealed, and extracted with stirring at 80°C for 4 hours before cooling to room temperature. The mixture was then stripped with n-hexane, chloroform, and ether in a 1:2 mass ratio. After stripping with each solvent, the tobacco dust and the organic solvent were separated by centrifugation. The supernatants were collected and combined, and the organic solvent was removed by vacuum distillation to obtain a black paste-like incense raw material. The main components identified were 8 alcohols, 10 ketones, and 9 nitrogen heterocycles.

[0039] Example 4

[0040] The oriental tobacco was dried at 60°C for 30 minutes, then crushed and passed through a 60-mesh sieve. The tobacco dust was mixed with a choline glycinate ([Cho]Gly) ionic liquid at a mass ratio of 1:2.5, sealed, and extracted with n-octane, dichloromethane, and butyl acetate in a 1:2 mass ratio. After stripping with each solvent, the tobacco dust and the organic solvent were separated by centrifugation. The supernatants were collected and combined, and the organic solvent was removed by vacuum distillation. The aromatic raw material was dissolved in twice the mass of ethanol, and the ethanol and residual ethyl acetate were removed by vacuum distillation. This process was repeated twice to obtain a black paste of aromatic raw material. The main components identified were five alcohols, 12 ketones, and six nitrogen heterocycles.

[0041] Comparative Example 1

[0042] Burley tobacco was dried at 60°C for 30 minutes, then ground and passed through a 60-mesh sieve. The tobacco dust was mixed with 1-ethyl-3-methylimidazolium nitrate ([EMIm]NO3) ionic liquid in a 1:2 mass ratio, sealed, and extracted with n-octane at 20°C for 0.5 hours before cooling to room temperature. The tobacco dust was then stripped with n-octane at a 1:2 mass ratio, centrifuged to separate the tobacco dust and the organic solvent, and the supernatant was collected and distilled under reduced pressure to remove the organic solvent, yielding a brown incense raw material. The main components identified were four alcohols, five ketones, and four nitrogen heterocycles.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting tobacco aroma raw materials using ionic liquid as an extractant, characterized in that: include: S1: crushing and sieving tobacco raw materials to obtain tobacco powder; S2: mixing tobacco dust and ionic liquid at a set mass ratio, sealing, extracting the tobacco dust with the ionic liquid, cooling to room temperature, and then stripping with an organic solvent. Centrifuging to separate the tobacco dust and the organic solvent, collecting the supernatant, and removing the organic solvent by vacuum distillation to obtain a tobacco aroma raw material; The ionic liquid is selected from one or more of 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-allyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium nitrate, and choline glycinate; The mass ratio of the tobacco dust to the ionic liquid is 1:(2-10); the ionic liquid extraction time is 0.5-24 hours, and the extraction temperature is 20-90°C; The organic solvent used in the stripping is selected from a combination of three solvents of different polarities among n-hexane, n-octane, ether, methyl tert-butyl ether, dichloromethane, chloroform and ethyl acetate.

2. The method according to claim 1, characterized in that In step S1, the tobacco raw material is one or a mixture of flue-cured tobacco, burley tobacco, oriental tobacco, sun-cured tobacco, Maryland tobacco, and cigar tobacco.

3. The method according to claim 1, characterized in that The mass ratio of the tobacco dust to the ionic liquid is 1:(2-4).

4. The method according to claim 1, wherein The ionic liquid extraction time is 2-6 hours, and the extraction temperature is 40-70°C.

5. A tobacco aroma raw material, characterized in that: Prepared by the method according to any one of claims 1 to 4.

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