阅读说明：本技术 一种降低烟草提取物中低碳烷烃的方法 (Method for reducing low-carbon alkane in tobacco extract ) 是由 何保江 郝菊芳 徐秀娟 史清照 霍现宽 刘珊 姬凌波 马骥 屈展 杨春强 宗永立 于 2020-05-11 设计创作，主要内容包括：本发明属于烟用香精香料技术领域,具体涉及一种降低烟草提取物中低碳烷烃的方法。本发明的方法包括以下步骤：(1)烟叶样品经亚临界萃取得烟草粗提物,将烟草粗提物经醇沉除杂得提取液,然后将提取液浓缩得浓缩物；(2)然后将浓缩物进行分子蒸馏分离,所述分子蒸馏的温度为40～80℃,压力为0.001～0.01mbar,脱除轻组分,剩余重组分即为烟草提取物。本发明的方法有效降低了烟草提取物中低碳烷烃的含量,降低了烟草提取物的杂气和刺激性,改善其感官品质。(The invention belongs to the technical field of tobacco flavors and fragrances, and particularly relates to a method for reducing low-carbon alkane in a tobacco extract. The method of the invention comprises the following steps: (1) carrying out subcritical extraction on a tobacco sample to obtain a tobacco crude extract, carrying out alcohol precipitation on the tobacco crude extract to remove impurities to obtain an extracting solution, and then concentrating the extracting solution to obtain a concentrate; (2) and then carrying out molecular distillation separation on the concentrate, wherein the temperature of the molecular distillation is 40-80 ℃, the pressure is 0.001-0.01 mbar, removing light components, and obtaining the residual heavy components, namely the tobacco extract. The method of the invention effectively reduces the content of low-carbon alkane in the tobacco extract, reduces the miscellaneous gas and irritation of the tobacco extract and improves the sensory quality of the tobacco extract.)

1. A method for reducing lower alkane in tobacco extract is characterized by comprising the following steps:

(1) carrying out subcritical extraction on a tobacco sample to obtain a tobacco crude extract, carrying out alcohol precipitation on the tobacco crude extract to remove impurities to obtain an extracting solution, and then concentrating the extracting solution to obtain a concentrate;

(2) and then carrying out molecular distillation separation on the concentrate, wherein the temperature of the molecular distillation is 40-80 ℃, the pressure is 0.001-0.01 mbar, removing light components, and obtaining the residual heavy components, namely the tobacco extract.

2. The method for reducing lower alkanes in tobacco extracts according to claim 1, wherein the pressure of the molecular distillation in step (2) is 0.001-0.009 mbar.

3. The method for reducing lower alkanes in tobacco extracts according to claim 1 or 2, wherein the step of performing subcritical extraction on tobacco leaf samples to obtain crude tobacco extracts comprises the following steps: mixing the tobacco sample and an extracting agent, extracting at the temperature of 25-50 ℃, wherein the pressure used in the extraction is the saturated vapor pressure of the extracting agent at the temperature of 25-50 ℃ to obtain an extraction liquid, and then removing the solvent in the extraction liquid to obtain the crude tobacco extract.

4. The method for reducing lower alkanes in tobacco extracts according to claim 3, wherein said extractant is butane and/or dimethyl ether.

5. The method for reducing lower alkanes in tobacco extracts according to claim 3, wherein the mass ratio of the extracting agent to the tobacco leaf samples is (8-20): 1.

6. the method for reducing lower alkanes in tobacco extracts according to claim 3, wherein an entrainer is further used in the subcritical extraction, and the amount of the entrainer is not more than 10% of the volume of the extractant; the entrainer is absolute ethyl alcohol or an ethyl alcohol water solution with the mass concentration higher than 90%.

7. The method for reducing lower alkanes in tobacco extracts according to claim 1 or 2, wherein the alcohol precipitation impurity removal specifically comprises: mixing the crude tobacco extract with ethanol, then preserving the heat for 20-60 min at the temperature of 30-50 ℃, cooling to room temperature, then freezing for 8-24 h at the temperature of-20-5 ℃, and then carrying out solid-liquid separation to obtain an extracting solution.

8. The method for reducing lower alkanes in tobacco extracts according to claim 7, wherein the mass of the ethanol is 5-10 times of that of the crude tobacco extract.

9. The method for reducing lower alkanes in tobacco extracts according to claim 1 or 2, wherein the tobacco sample is one or more of flue-cured tobacco, sun-cured tobacco, aromatic tobacco and burley tobacco.

Technical Field

The invention belongs to the technical field of tobacco flavors and fragrances, and particularly relates to a method for reducing low-carbon alkane in a tobacco extract.

Background

The tobacco extract is extracted from tobacco, contains tobacco intrinsic aroma components, has the advantages of natural and harmonious aroma, compensation of the intrinsic aroma of the tobacco, prominent style characteristics and the like, and is irreplaceable tobacco flavor in the cigarette aroma blending and novel tobacco product development process. At present, most of commercially available tobacco extracts are obtained by mixing ethanol solvent with tobacco and then heating and extracting, and fine separation is not carried out, so that the components of the product are complex. The characteristic endows the tobacco extract with natural feeling and richness, and simultaneously causes the problems of low content of aroma components, unsharp style and the like.

The volatile components of tobacco extract generally contain substances such as alcohols, ketones, alkanes, alkenes, and nitrogen-containing heterocycles. The alkane substances do not contribute to cigarette smell and smoking, and the existence of the alkane can cause the problems of poor solubility of the tobacco extract, low content of aroma components, indistinct organoleptic style and characteristics and the like. Therefore, effectively reducing the content of useless alkane components is crucial to improving the sensory quality of the tobacco extract.

Alkanes, especially n-hentriacontane and n-heptacosane, are the main components of the wax on the surface of tobacco leaves, and the solubility in ethanol decreases with decreasing temperature. Therefore, the tobacco extract can be removed by an alcohol precipitation method (namely, a method of ethanol redissolution and low-temperature freezing is adopted for removal) in the preparation process of the tobacco extract. However, low-carbon alkanes with low molecular weight (the number of carbon atoms is not more than 20) are mostly liquid at normal temperature, have good solubility in ethanol, and cannot be removed by an alcohol precipitation impurity removal method. No related report for effectively removing the low-carbon alkane exists in the prior art.

Disclosure of Invention

The invention aims to provide a method for reducing low-carbon alkane in a tobacco extract, which can effectively reduce the low-carbon alkane in the tobacco extract.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for reducing lower alkanes in tobacco extracts comprises the following steps:

(1) carrying out subcritical extraction on a tobacco sample to obtain a tobacco crude extract, carrying out alcohol precipitation on the tobacco crude extract to remove impurities to obtain an extracting solution, and then concentrating the extracting solution to obtain a concentrate;

(2) and then carrying out molecular distillation separation on the concentrate, wherein the temperature of the molecular distillation is 40-80 ℃, the pressure is 0.001-0.01 mbar, removing light components, and obtaining the residual heavy components, namely the tobacco extract.

The method adopts a subcritical extraction technology to obtain crude tobacco extraction, then adopts an alcohol precipitation impurity removal method to remove high-carbon alkane in the crude tobacco extraction, and then adopts a molecular distillation method to remove low-carbon alkane in the crude tobacco extraction. During molecular distillation, low temperature and pressure are adopted to effectively enrich the low-carbon alkane in the light component, so that the content of the low-carbon alkane in the tobacco extract is effectively reduced, the offensive odor and irritation of the tobacco extract are reduced, and the sensory quality of the tobacco extract is improved.

Preferably, the pressure used during molecular distillation is 0.001 to 0.009 mbar.

In order to improve the effective components in the crude tobacco extract, preferably, the step of performing subcritical extraction on a tobacco leaf sample to obtain the crude tobacco extract specifically comprises the following steps: mixing the tobacco sample and an extracting agent, extracting at the temperature of 25-50 ℃, wherein the pressure used in the extraction is the saturated vapor pressure of the extracting agent at the temperature of 25-50 ℃ to obtain an extraction liquid, and then removing the solvent in the extraction liquid to obtain the crude tobacco extract. The obtained tobacco crude extract is in the form of extractum.

Preferably, the extractant is butane and/or dimethyl ether.

In order to extract the effective components in the tobacco leaf sample as much as possible, the mass ratio of the extracting agent to the tobacco leaf sample is preferably (8-20): 1.

the extraction efficiency of the tobacco aroma components is improved by adopting the entrainer in the subcritical extraction process, so that the entrainer is preferably used in the subcritical extraction in the method disclosed by the invention, and the use amount of the entrainer is not more than 10% of the volume of the extractant; the entrainer is absolute ethyl alcohol or an ethyl alcohol water solution with the mass concentration higher than 90%.

The alcohol precipitation impurity removal specifically comprises the following steps: mixing the crude tobacco extract with ethanol, then preserving the heat for 20-60 min at the temperature of 30-50 ℃, cooling to room temperature, then freezing for 8-24 h at the temperature of-20-5 ℃, and then carrying out solid-liquid separation to obtain an extracting solution. In the alcohol precipitation and impurity removal process, the tobacco extract is dissolved at the temperature of 30-50 ℃, then high-carbon alkane in the tobacco extract is precipitated due to the fact that the solubility of the high-carbon alkane in ethanol is reduced in the freezing process, and then the high-carbon alkane is removed through solid-liquid separation.

When the alcohol precipitation is used for removing impurities, the amount of the ethanol is only required to be capable of completely dissolving the tobacco crude extract. Preferably, the mass of the ethanol is 5-10 times of that of the tobacco crude extract. The ethanol can be absolute ethanol or a commercially available ethanol water solution with the mass concentration higher than 90 percent.

The method is applicable to most of the existing tobacco leaf samples, and the preferred tobacco leaf samples are one or more of flue-cured tobacco, sun-cured tobacco, aromatic tobacco and burley tobacco. The tobacco leaf samples are tobacco leaf samples crushed to 50-100 meshes.

Detailed Description

The present invention will be further described with reference to the following specific examples.

Example 1

The method for reducing lower alkanes in the tobacco extract of the embodiment comprises the following steps:

(1) crushing tobacco leaves to 100 meshes, transferring the tobacco leaves to a subcritical extraction kettle, adding dimethyl ether (the mass ratio of dimethyl ether to tobacco leaves is 8: 1) and 95% ethanol entrainer (5% of the volume of dimethyl ether), and extracting at 25 ℃ for 2 hours under the extraction pressure of saturated vapor pressure of dimethyl ether at 25 ℃ to obtain extract liquor; evaporating under reduced pressure to remove solvent in the extract to obtain tobacco crude extract;

(2) adding 5 times of 95% ethanol into the crude extract, heating to 30 deg.C, and maintaining for 60min to dissolve completely; cooling to room temperature, transferring to a refrigerator with the temperature of-20 ℃, freezing for 8h, performing suction filtration at low temperature to obtain an extracting solution, and performing reduced pressure concentration on the extracting solution until no ethanol exists to obtain a concentrate;

(3) the concentrate was placed in a molecular distillation feed tank and distilled at 60 ℃ under 0.001mbar, after which the light and heavy fractions were collected separately. Wherein the light component is light yellow flowable liquid, and the yield is 2.2%; the heavy fraction (tobacco extract) was a tan viscous liquid with a yield of 97.8%.

Example 2

The method for reducing lower alkanes in the tobacco extract of the embodiment comprises the following steps:

(1) crushing tobacco leaves to 100 meshes, transferring the tobacco leaves to a subcritical extraction kettle, adding dimethyl ether (the mass ratio of dimethyl ether to tobacco leaves is 10:1) and an absolute ethyl alcohol entrainer (10% of the volume of dimethyl ether), and extracting at 40 ℃ for 0.5h, wherein the extraction pressure is the saturated steam pressure of the dimethyl ether at 40 ℃ to obtain an extraction liquid; evaporating under reduced pressure to remove solvent in the extract to obtain tobacco crude extract;

(2) adding 10 times of anhydrous ethanol into the crude tobacco extract, heating to 50 deg.C, and maintaining for 20min for dissolving completely; cooling to room temperature, freezing in a refrigerator at-5 deg.C for 24 hr, centrifuging at low temperature (4000 rpm for 10min) to obtain supernatant, and concentrating under reduced pressure until ethanol is removed to obtain concentrate;

(3) the concentrate was placed in a molecular distillation feed tank and distilled at 80 ℃ under 0.01mbar, after which the light and heavy fractions were collected separately. Wherein the light component is light yellow flowable liquid, and the yield is 3.27%; the heavy fraction (tobacco extract) was a tan viscous liquid with a yield of 96.73%.

Example 3

The method for reducing lower alkanes in the tobacco extract of the embodiment comprises the following steps:

(1) pulverizing tobacco leaves to 50 meshes, transferring to a subcritical extraction kettle, adding butane (the mass ratio of butane to tobacco leaves is 20:1), and extracting at 50 deg.C for 1h under the saturated vapor pressure of butane at 50 deg.C to obtain extractive solution; evaporating under reduced pressure to remove solvent in the extract to obtain tobacco crude extract;

(2) adding 8 times of anhydrous ethanol into the crude tobacco extract, heating to 40 deg.C, and maintaining for 40min for dissolving completely; cooling to room temperature, freezing in a refrigerator at-15 deg.C for 12h, centrifuging at low temperature (4000 rpm for 10min) to obtain supernatant, and concentrating under reduced pressure until ethanol is removed to obtain concentrate;

(3) the concentrate was placed in a molecular distillation feed tank and distilled at 40 ℃ under 0.001mbar, after which the light and heavy fractions were collected separately. Wherein the light component is light yellow flowable liquid, and the yield is 1.87%; the heavy fraction (tobacco extract) was a tan viscous liquid with a yield of 98.13%.

Test example 1

In this test example, the light components and the heavy components obtained in examples 1 and 2 were analyzed by gas chromatography-mass spectrometry (GC-MS), and specifically, the light alkane components were: weighing a certain amount of light components and the tobacco extract, dissolving the light components and the tobacco extract by using absolute ethyl alcohol, adding an internal standard phenethyl acetate, and then carrying out sample injection test analysis. The conditions for GC-MS when testing the analysis are as follows:

a chromatographic column: DB-5MS capillary column (30m 0.25mm 0.25 μm); sample inlet temperature: 250 ℃; carrier gas: high purity helium gas; the flow rate is 1.0 mL/min; sample introduction amount: 1 mu L of the solution; the split ratio is 10: 1; temperature programming: keeping the temperature at 50 deg.C for 2min, heating to 270 deg.C at a heating rate of 5 deg.C/min, and keeping for 10 min.

An ionization mode: EI; ion source temperature: 230 ℃; electron energy: 70 eV; quadrupole temperature: 150 ℃; electron multiplier voltage: 1.89 kV; the mass scanning range is 33-500 amu; the scanning mode is as follows: full scanning; solvent retardation: 7.0 min.

Wherein the light components obtained in example 1 and the types and contents of the lower alkanes in the tobacco extract are shown in Table 1.

TABLE 1 light fraction and lower alkane species and content in tobacco extract

Wherein the light components obtained in example 2 and the types and contents of the lower alkanes in the tobacco extract are shown in Table 2.

TABLE 2 light fraction and lower alkane species and content in tobacco extract

Note: table 1 and table 2-indicate no detection.

As can be seen from tables 1 and 2, the method of the invention enables most of the light alkanes to be enriched in the light components, so that the content of the light alkanes in the tobacco extract is greatly reduced and is only 0.29-0.6% of the light components.

Test example 2

In this test example, the concentrate obtained in example 3 and the tobacco extract were each diluted with 95% ethanol to a 10% ethanol solution by mass concentration, and then injected into a blank cigarette using an automatic injection and flavor machine at an injection amount of 1 μ L/cigarette. After the injection, the cigarettes were put into a cigarette case, sealed and left for 1 week at 22 ± 2 ℃ and RH (humidity) of 60% ± 5%, and then the perfuming effect was evaluated, and the sensory evaluation results are shown in table 3.

TABLE 3 sensory evaluation results

Note: when the average score is more than 11.2, the index is obviously improved, and the higher the score is, the higher the improvement degree is.

Evaluation results show that after the low-carbon alkane is removed, the aroma quality and the aroma amount of the tobacco extract are obviously improved, miscellaneous gas is reduced, the fineness and the softness of smoke are increased, and the residue and the irritation are reduced; meanwhile, the flower fragrance, the cream fragrance, the baking fragrance and the sweet fragrance are more prominent.