A waste tobacco extract and a method of preparing the same

Abstract

The present application relates to a kind of preparation methods of waste tobacco extract, waste tobacco is crushed, enzymolysis, organic solvent ultrasonic extraction obtains methylene chloride extract S1 and ethyl acetate extract S2;After enzymolysis treatment, tobacco powder is fermented, subcritical water extraction, heavy metal adsorption and nanofiltration membrane filtration, nanofiltration membrane permeate is concentrated to obtain concentrated extract, concentrated extract is carried out molecular distillation, the light component and heavy component of molecular distillation are collected, the light component is water extract S3, and the heavy component is water extract S4;Concentrated extract is obtained by concentrating the cut-off liquid, and is recorded as water extract S5;The waste tobacco extract is one or more than two of methylene chloride extract S1, ethyl acetate extract S2, water extract S3, water extract S4 and water extract S5.The extract contains a large amount of tobacco native substance, has strong tobacco style characteristics, and higher safety, and it is applied to cigarette, can significantly improve the sensory quality of cigarette.

Description

An extract from waste tobacco leaves and its preparation method Technical Field

[0001] This invention belongs to the field of tobacco extraction technology, specifically relating to an extract from waste tobacco leaves and its preparation method. Background Technology

[0002] In recent years, my country's tobacco production has been enormous, resulting in a large amount of waste tobacco leaves annually, such as tobacco by-products, re-drying plant dust, and low-quality stockpiled tobacco leaves. While waste tobacco leaves contain a significant amount of important tobacco aroma components, their relative chemical content differs considerably from that of high-quality tobacco leaves. Consequently, waste tobacco leaves suffer from various sensory quality problems, including poor aroma, strong off-flavors, high irritation, and lingering aftertaste. Currently, the utilization rate of waste tobacco leaves is low, which not only wastes resources but also pollutes the environment if improperly handled. Currently, waste tobacco leaves are mainly used for high-intensity processing or as raw materials for reconstituted tobacco. While high-intensity processing can alleviate the problem of strong off-flavors to some extent, it results in a significant loss of aroma substances, primarily limiting its use as filler modules. In the papermaking process for reconstituted tobacco, the raw materials undergo high-intensity evaporation processes such as hot water extraction, vacuum concentration, and coating drying, also leading to substantial loss of aroma components. CN102851241 A discloses a method for preparing a reduced-irritation fermented tobacco leaf extract and its application in recombinant tobacco leaves. This method utilizes a bacterial strain, involving strain activation, preparation of seed culture, fermentation culture, and conversion of the fermentation broth to obtain the reduced-irritation fermented tobacco leaf extract. However, related technologies concerning waste tobacco leaf extracts still require further in-depth research.

[0003] Based on this, this application was developed. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a waste tobacco leaf extract. The extract prepared from waste tobacco leaves contains a large number of tobacco aroma substances, has a strong tobacco flavor, and is safer. When applied to cigarettes, it can significantly improve the sensory quality of cigarettes.

[0005] The present invention also provides a method for preparing the above-mentioned waste tobacco leaf extract.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing an extract from waste tobacco leaves, comprising the following steps:

[0008] 1) Crushing

[0009] Waste tobacco leaves are pulverized using a turbine pulverizer until the pulverized tobacco leaves have a 60-mesh passing rate of over 99% to obtain tobacco powder;

[0010] 2) Enzymatic hydrolysis

[0011] Tobacco powder was treated with a compound enzyme solution to obtain an enzyme-treated tobacco powder mixture; the compound enzyme used was one or more of pectinase, cellulase, laccase, protease, etc.

[0012] 3) Ultrasonic extraction with organic solvents

[0013] The enzyme-treated tobacco powder mixture obtained in step 2) was partially dehydrated to control the water content at 20%-40%. Then, it was extracted by ultrasonic extraction with dichloromethane and ethyl acetate in sequence. After extraction, the organic solvent was removed by vacuum distillation to obtain dichloromethane extract S1 and ethyl acetate extract S2 of tobacco powder, respectively.

[0014] 4) Subcritical water extract of tobacco

[0015] a. Fermentation produces aroma

[0016] After sterilizing the enzyme-treated tobacco powder mixture obtained in step 2) (using saturated steam for sterilization at a temperature of 110-140℃ for 10-30 minutes), inoculate it with the culture broth of aroma-producing fermentation fungi, and then ferment at room temperature for 2.5-3 days to obtain the fermented tobacco powder mixture.

[0017] The aroma-producing bacteria are one or more of yeast, Bacillus subtilis, Bacillus licheniformis, etc. The aroma-producing bacteria are activated and cultured according to conventional methods in the art to obtain an aroma-producing bacteria culture broth; the inoculum amount of the aroma-producing bacteria culture broth is 1.0%-5.0% of the material mass;

[0018] b. Subcritical extraction of fermented tobacco powder

[0019] The fermented tobacco powder mixture was subjected to subcritical extraction with water to obtain a subcritical water extract.

[0020] c. Adsorption of heavy metals in subcritical water extract

[0021] Add a heavy metal adsorbent (such as one or more of zeolite, diatomaceous earth, polyaluminum chloride, dithiocarbamate, modified cellulose, bentonite, etc.) to the subcritical water extract and shake to adsorb for 1.5-3 hours, then separate the solid and liquid. The ratio of subcritical water extract to adsorbent is 200ml:1-3g.

[0022] d. Membrane separation

[0023] The subcritical water extract after heavy metal adsorption was sent to a nanofiltration membrane for filtration to obtain nanofiltration membrane permeate and retentate.

[0024] e. Concentration and molecular distillation separation

[0025] The permeate from the nanofiltration membrane was concentrated to obtain a concentrated extract; the concentrated extract was subjected to molecular distillation to collect the light and heavy components of the molecular distillation. The light component was water extract S3, and the heavy component was water extract S4.

[0026] The retentate was concentrated to obtain a concentrated extract, denoted as aqueous extract S5.

[0027] The waste tobacco extract is one or more of the following: dichloromethane extract S1, ethyl acetate extract S2, water extract S3, water extract S4, and water extract S5.

[0028] Specifically, in step 2), the concentration of the compound enzyme solution is 10-30%, the amount of compound enzyme solution used is 0.5-3% of the mass of tobacco powder, the enzyme treatment temperature is 30-50℃, the enzyme treatment humidity is 60-80%, and the enzymatic hydrolysis time is 22-30h.

[0029] Furthermore, in step 3), during dichloromethane extraction, the mass ratio of tobacco powder to dichloromethane is 1:3-10, preferably 1:5-7, the extraction temperature is 20-40℃, and the extraction time is 0.5-3h, preferably 1-2h.

[0030] After dichloromethane extraction, solid and liquid separation is performed. The solid material is then further extracted with ethyl acetate. The mass ratio of tobacco powder to ethyl acetate is 1:2-5, preferably 1:3-5. The extraction temperature is 70-90℃, and the extraction time is 0.5-3h, preferably 1-2h.

[0031] When extracting with organic solvents, the ultrasonic power is 20-40 kHz.

[0032] Specifically, in step 4), during subcritical extraction, the mass ratio of the fermented tobacco powder mixture to the water used for subcritical extraction is 1:3-7, preferably 1:4-6. The extraction temperature is 150-160℃, and the extraction time is 10-60 min. The extraction is performed 1-5 times, preferably 2-3 times, to obtain a subcritical water extract.

[0033] Furthermore, in step 4), after the shaking adsorption is completed, the heavy metal adsorbent can be separated from the subcritical water extract by filtration. The heavy metal adsorbent after shaking adsorption can be reused after elution with dilute acid, washing with water until neutral, and drying. The dilute acid is one or more combinations of nitric acid, hydrochloric acid, sulfuric acid, aminosulfonic acid, etc., and the concentration of the dilute acid is 0.01-1.0 mol / L.

[0034] Specifically, in step 4), the nanofiltration membrane is a tubular nanofiltration membrane with a pore size of 10-100 nm. During nanofiltration, the operating pressure is ≤6.0 BAR. The permeate from the nanofiltration membrane is concentrated by vacuum distillation to obtain a concentrated extract. The vacuum distillation temperature is 45-65℃, and the pressure is 0.08-0.97 MPa. The concentrated extract is then subjected to molecular distillation, and the light and heavy components are collected to obtain a tobacco extract with aroma-enhancing properties after heavy metal removal.

[0035] Further preferably, in step 4), the molecular distillation is a two-stage molecular distillation. The light components from the first and second stage molecular distillations are combined to obtain the water extract S3, and the remaining heavy components are the water extract S4. The heating temperature for the first stage molecular distillation is 50–80℃, the pressure is 100–200 Pa, the feed rate is 300–600 mL / h, and the scraping speed is 200–300 rpm. The heating temperature for the second stage molecular distillation is 90–110℃, the pressure is 40–60 Pa, the feed rate is 300–600 mL / h, and the scraping speed is 200–300 rpm. The retentate is concentrated by vacuum distillation to obtain a concentrated extract. The vacuum distillation temperature is 45–65℃, and the pressure is 0.08–0.97 MPa.

[0036] The present invention provides a waste tobacco leaf extract prepared by the above preparation method, wherein, by weight, the waste tobacco leaf extract comprises 30-50 parts of dichloromethane extract S1, 60-80 parts of ethyl acetate extract S2 and 10-20 parts of water extract, wherein the water extract is one or more of water extract S3, water extract S4 and water extract S5.

[0037] This invention provides the application of the above-mentioned waste tobacco extract in cigarettes.

[0038] The present invention also provides a cigarette containing the aforementioned waste tobacco extract.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The refined extract based on waste tobacco leaves obtained by the method of this invention contains a large amount of tobacco aroma substances. After enzymatic hydrolysis, cell wall substances such as tobacco cellulose and pectin are destroyed, which is beneficial to subsequent extraction reactions. Among them, the dichloromethane extract and ethyl acetate extract are compounds composed of typical polar molecules, which generally have a better flavoring effect than tobacco paste or oil paste. After the reaction with aroma-producing fungi, the content of tobacco aroma substances can be further increased. Subcritical water extraction can maximize the extraction of tobacco aroma substances. After molecular distillation, the components with different functions are separated. The retentate is used very little in the actual recombination of extract components. Therefore, the final recombined and blended extract has a strong tobacco style characteristic. Moreover, after the removal of heavy metal ions, it is safer. When applied to cigarettes, it can significantly improve the sensory quality of cigarettes. Attached Figure Description

[0041] Figure 1 is a process flow diagram for preparing waste tobacco leaf extract according to the present invention. Detailed Implementation

[0042] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0043] In this invention, unless otherwise specified, percentages (%) refer to mass percentages. Room temperature refers to 25±5℃. Processes or operations not mentioned in detail can be performed using conventional techniques in the field.

[0044] In the following examples, the pectinase, cellulase, laccase, and protease used were all food grade. The pectinase and cellulase were sold by Henan Junyi Biotechnology Co., Ltd., with enzyme activities of 30,000 U and 100,000 U, respectively; the laccase was sold by Zhejiang Tianhe Food Biotechnology Co., Ltd., with an enzyme activity of 100,000 U; and the protease was an acidic protease sold by Henan Wanbang Chemical Technology Co., Ltd., with an enzyme activity of 100,000 U.

[0045] Example 1

[0046] A method for preparing an extract from waste tobacco leaves, comprising the following steps:

[0047] 1) Crushing

[0048] Waste tobacco leaves are pulverized using a turbine pulverizer until the 60-mesh passing rate of the pulverized tobacco leaves reaches 99%, thus obtaining tobacco powder.

[0049] 2) Enzymatic hydrolysis

[0050] Tobacco powder was treated with a compound enzyme solution to obtain an enzyme-treated tobacco powder mixture. The compound enzyme used was a mixture of pectinase and cellulase in a 1:1 mass ratio. The concentration of the compound enzyme solution was 20%, the amount of the compound enzyme solution was 2% of the mass of the tobacco powder, the enzyme treatment temperature was 40℃, the enzyme treatment humidity was 70%, and the enzymatic hydrolysis time was 26h.

[0051] 3) Ultrasonic extraction with organic solvents

[0052] The enzyme-treated tobacco powder mixture obtained in step 2) was partially dehydrated to control the water content at 30%. Then, it was subjected to ultrasonic extraction with dichloromethane and ethyl acetate in sequence. After extraction, the organic solvent was removed by vacuum distillation to obtain dichloromethane extract S1 and ethyl acetate extract S2 of the tobacco powder, respectively. For easy transfer and storage, S1 and S2 can be reconstituted with anhydrous ethanol to 40% and 70% of the weight of the tobacco powder, respectively.

[0053] When extracting with dichloromethane, the mass ratio of tobacco powder to dichloromethane is 1:6, the extraction temperature is 30℃, and the extraction time is 1 hour.

[0054] After dichloromethane extraction, the material was filtered, and the solid material was further extracted with ethyl acetate at a mass ratio of 1:4 for tobacco powder to ethyl acetate, an extraction temperature of 80℃, and an extraction time of 2 hours.

[0055] When extracting with organic solvents, the ultrasonic power is 30 kHz.

[0056] 4) Subcritical water extract of tobacco

[0057] a. Fermentation produces aroma

[0058] After sterilizing the enzyme-treated tobacco powder mixture obtained in step 2) (using saturated steam for sterilization at 121°C for 10 min), inoculate it with the fermentation aroma-producing fungus culture and then ferment at room temperature for 3 days to obtain the fermented tobacco powder mixture.

[0059] The aroma-producing fungus is aroma-producing yeast YG-4. YG-4 is inoculated into YPD liquid culture medium and activated by shaking culture at 30°C for 48 hours to obtain the aroma-producing fungus culture broth. The inoculation amount of the aroma-producing fungus culture broth is 3.0% of the material mass.

[0060] b. Subcritical extraction of the fermented tobacco powder:

[0061] The fermented tobacco powder mixture was subjected to subcritical extraction with water to obtain a subcritical water extract. During subcritical extraction, the mass ratio of the fermented tobacco powder mixture to the water used for subcritical extraction was 1:5, the extraction temperature was 155℃, and the extraction time was 30 min. The extraction was performed three times.

[0062] c. Adsorption of heavy metals in subcritical water extract

[0063] Add 100-mesh natural zeolite powder, a heavy metal adsorbent, to the subcritical water extract and shake to adsorb for 2 hours, then filter. The ratio of subcritical water extract to adsorbent is 200ml:2g.

[0064] After the shaking adsorption is completed, the heavy metal adsorbent is separated from the subcritical water extract by filtration. The heavy metal adsorbent after shaking adsorption can be reused by eluting with dilute acid, washing with water until neutral, and drying. The dilute acid is nitric acid with a concentration of 0.5 mol / L.

[0065] d. Membrane separation

[0066] The subcritical water extract after heavy metal adsorption is passed through a nanofiltration membrane for filtration to obtain a nanofiltration membrane permeate and a retentate. The nanofiltration membrane is a tubular nanofiltration membrane with a pore size of 40-60 nm. The operating pressure during nanofiltration is 6.0 BAR.

[0067] Concentration and molecular distillation separation

[0068] The permeate from the nanofiltration membrane was concentrated by vacuum distillation to obtain a concentrated extract. The concentrated extract was then subjected to molecular distillation to collect the light and heavy components. The light component was identified as water extract S3, and the heavy component as water extract S4. The vacuum distillation was carried out at a temperature of 55°C and a pressure of 0.5 MPa.

[0069] The molecular distillation is a two-stage molecular distillation. The light fractions from the first and second stage molecular distillations are combined to form the water extract S3, while the remaining heavy fraction is the water extract S4. The heating temperature for the first stage molecular distillation is 65℃, the pressure is 150Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm. The heating temperature for the second stage molecular distillation is 100℃, the pressure is 50Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm.

[0070] The retentate was concentrated to obtain a concentrated extract, denoted as water extract S5; the retentate was concentrated by vacuum distillation at a temperature of 55°C and a pressure of 0.5 MPa to obtain a concentrated extract.

[0071] This embodiment provides a waste tobacco leaf extract prepared by the above preparation method. By weight, the waste tobacco leaf extract includes 40 parts of dichloromethane extract S1, 70 parts of ethyl acetate extract S2 and 15 parts of water extract, wherein the water extract is water extract S3 and water extract S4 in a mass ratio of 1:1.

[0072] Example 2

[0073] A method for preparing an extract from waste tobacco leaves, comprising the following steps:

[0074] 1) Crushing

[0075] Waste tobacco leaves are pulverized using a turbine pulverizer until the pulverized tobacco leaves have a 60-mesh passing rate of over 99% to obtain tobacco powder;

[0076] 2) Enzymatic hydrolysis

[0077] Tobacco powder was treated with a compound enzyme solution to obtain an enzyme-treated tobacco powder mixture. The compound enzyme used was a mixture of cellulase and laccase in a mass ratio of 1:3. The concentration of the compound enzyme solution was 30%, the amount of the compound enzyme solution was 1% of the mass of the tobacco powder, the enzyme treatment temperature was 50℃, the enzyme treatment humidity was 80%, and the enzymatic hydrolysis time was 24h.

[0078] 3) Ultrasonic extraction with organic solvents

[0079] The enzyme-treated tobacco powder mixture obtained in step 2) was partially dehydrated to control the water content at 25%. Then, it was subjected to ultrasonic extraction with dichloromethane and ethyl acetate in sequence. After extraction, the organic solvent was removed by vacuum distillation to obtain dichloromethane extract S1 and ethyl acetate extract S2 of the tobacco powder, respectively. S1 and S2 were then redissolved in anhydrous ethanol to 40% and 70% of the weight of the tobacco powder, respectively.

[0080] When extracting with dichloromethane, the mass ratio of tobacco powder to dichloromethane is 1:4, the extraction temperature is 30℃, and the extraction time is 2h.

[0081] After dichloromethane extraction, the material was filtered, and the solid material was further extracted with ethyl acetate at a mass ratio of 1:3 for tobacco powder to ethyl acetate, an extraction temperature of 85℃, and an extraction time of 1 hour.

[0082] When extracting with organic solvents, the ultrasonic power is 25 kHz.

[0083] 4) Subcritical water extract of tobacco

[0084] a. Fermentation produces aroma

[0085] After sterilizing the enzyme-treated tobacco powder mixture obtained in step 2) (using saturated steam for sterilization at 121°C for 10 min), inoculate it with the fermentation aroma-producing fungus culture and then ferment at room temperature for 3 days to obtain the fermented tobacco powder mixture.

[0086] The aroma-producing fungus is aroma-producing yeast YG-4. YG-4 is inoculated into YPD liquid culture medium and activated by shaking culture at 30°C for 48 hours to obtain the aroma-producing fungus culture broth. The inoculation amount of the aroma-producing fungus culture broth is 3.0% of the material mass.

[0087] b. Subcritical extraction of the fermented tobacco powder:

[0088] The fermented tobacco powder mixture was subjected to subcritical extraction with water to obtain a subcritical water extract. During subcritical extraction, the mass ratio of the fermented tobacco powder mixture to the water used for subcritical extraction was 1:4, the extraction temperature was 150℃, and the extraction time was 50 min. The extraction was performed three times.

[0089] c. Adsorption of heavy metals in subcritical water extract

[0090] Add 200-mesh natural bentonite heavy metal adsorbent to the subcritical water extract, shake and adsorb for 2 hours, then filter; the ratio of subcritical water extract to adsorbent is 200ml:2g.

[0091] After the shaking adsorption is completed, the heavy metal adsorbent can be separated from the subcritical water extract by filtration. The heavy metal adsorbent after shaking adsorption can be reused by eluting with dilute acid, washing with water until neutral, and drying. The dilute acid is hydrochloric acid with a concentration of 0.05 mol / L.

[0092] d. Membrane separation

[0093] The subcritical water extract after heavy metal adsorption is passed through a nanofiltration membrane for filtration to obtain a nanofiltration membrane permeate and a retentate. The nanofiltration membrane is a tubular nanofiltration membrane with a pore size of 40-60 nm. The operating pressure during nanofiltration is 6.0 BAR.

[0094] Concentration and molecular distillation separation

[0095] The permeate from the nanofiltration membrane was concentrated by vacuum distillation to obtain a concentrated extract. The concentrated extract was then subjected to molecular distillation to collect the light and heavy components. The light component was identified as water extract S3, and the heavy component as water extract S4. The vacuum distillation was carried out at a temperature of 55°C and a pressure of 0.3 MPa.

[0096] The molecular distillation is a two-stage molecular distillation. The light fractions from the first and second stage molecular distillations are combined to form the water extract S3, while the remaining heavy fraction is the water extract S4. The heating temperature for the first stage molecular distillation is 65℃, the pressure is 150Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm. The heating temperature for the second stage molecular distillation is 100℃, the pressure is 50Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm.

[0097] The retentate was concentrated to obtain a concentrated extract, denoted as water extract S5; the retentate was concentrated by vacuum distillation at a temperature of 55°C and a pressure of 0.3 MPa to obtain a concentrated extract.

[0098] This embodiment provides a waste tobacco leaf extract prepared by the above preparation method. The waste tobacco leaf extract includes 40 parts by weight of dichloromethane extract S1, 70 parts by weight of ethyl acetate extract S2 and 15 parts by weight of water extract, wherein the water extract is water extract S3 and water extract S5 in a mass ratio of 1:1.

[0099] Example 3

[0100] A method for preparing an extract from waste tobacco leaves, comprising the following steps:

[0101] 1) Crushing

[0102] Waste tobacco leaves are pulverized using a turbine pulverizer until the pulverized tobacco leaves have a 60-mesh passing rate of over 99% to obtain tobacco powder;

[0103] 2) Enzymatic hydrolysis

[0104] Tobacco powder was enzymatically treated with a compound enzyme solution to obtain an enzyme-treated tobacco powder mixture. The compound enzyme used was a mixture of pectinase, laccase, and protease in a mass ratio of 1:1:1. The concentration of the compound enzyme solution was 12%, the amount of the compound enzyme solution was 3% of the mass of the tobacco powder, the enzyme treatment temperature was 40℃, the enzyme treatment humidity was 40%, and the enzymatic hydrolysis time was 28h.

[0105] 3) Ultrasonic extraction with organic solvents

[0106] The enzyme-treated tobacco powder mixture obtained in step 2) was partially dehydrated to control the water content at 35%. Then, it was subjected to ultrasonic extraction with dichloromethane and ethyl acetate in sequence. After extraction, the organic solvent was removed by vacuum distillation to obtain dichloromethane extract S1 and ethyl acetate extract S2 of the tobacco powder, respectively. S1 and S2 were then redissolved in anhydrous ethanol to 40% and 70% of the weight of the tobacco powder, respectively.

[0107] When extracting with dichloromethane, the mass ratio of tobacco powder to dichloromethane is 1:7, the extraction temperature is 30℃, and the extraction time is 2h.

[0108] After dichloromethane extraction, the material was filtered, and the solid material was further extracted with ethyl acetate at a mass ratio of 1:5 for tobacco powder to ethyl acetate, an extraction temperature of 75℃, and an extraction time of 2 hours.

[0109] When extracting with organic solvents, the ultrasonic power is 35 kHz.

[0110] 4) Subcritical water extract of tobacco

[0111] a. Fermentation produces aroma

[0112] After sterilizing the enzyme-treated tobacco powder mixture obtained in step 2) (using saturated steam for sterilization at 121°C for 10 min), inoculate it with the fermentation aroma-producing fungus culture and then ferment at room temperature for 3 days to obtain the fermented tobacco powder mixture.

[0113] The aroma-producing fungus is aroma-producing yeast YG-4. YG-4 is inoculated into YPD liquid culture medium and activated by shaking culture at 30°C for 48 hours to obtain the aroma-producing fungus culture broth. The inoculation amount of the aroma-producing fungus culture broth is 3.0% of the material mass.

[0114] b. Subcritical extraction of the fermented tobacco powder:

[0115] The fermented tobacco powder mixture was subjected to subcritical extraction with water to obtain a subcritical water extract. During subcritical extraction, the mass ratio of the fermented tobacco powder mixture to the water used for subcritical extraction was 1:6, the extraction temperature was 160℃, and the extraction time was 20 min. The extraction was performed twice.

[0116] c. Adsorption of heavy metals in subcritical water extract

[0117] Add 200-mesh natural diatomaceous earth heavy metal adsorbent to the subcritical water extract, shake and adsorb for 2 hours, then filter; the ratio of subcritical water extract to adsorbent is 200ml:2g.

[0118] After the shaking adsorption is completed, the heavy metal adsorbent can be separated from the subcritical water extract by filtration. The heavy metal adsorbent after shaking adsorption can be reused by eluting with dilute acid, washing with water until neutral, and drying. The dilute acid is aminosulfonic acid with a concentration of 0.2 mol / L.

[0119] d. Membrane separation

[0120] The subcritical water extract after heavy metal adsorption is passed through a nanofiltration membrane for filtration to obtain a nanofiltration membrane permeate and a retentate. The nanofiltration membrane is a tubular nanofiltration membrane with a pore size of 40-60 nm. The operating pressure during nanofiltration is 6.0 BAR.

[0121] Concentration and molecular distillation separation

[0122] The permeate from the nanofiltration membrane was concentrated by vacuum distillation to obtain a concentrated extract. The concentrated extract was then subjected to molecular distillation to collect the light and heavy components. The light component was identified as water extract S3, and the heavy component as water extract S4. The vacuum distillation was carried out at a temperature of 55°C and a pressure of 0.7 MPa.

[0123] The molecular distillation is a two-stage molecular distillation. The light fractions from the first and second stage molecular distillations are combined to form the water extract S3, while the remaining heavy fraction is the water extract S4. The heating temperature for the first stage molecular distillation is 65℃, the pressure is 150Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm. The heating temperature for the second stage molecular distillation is 100℃, the pressure is 50Pa, the feed rate is 450mL / h, and the scraping speed is 250rpm.

[0124] The retentate was concentrated to obtain a concentrated extract, denoted as water extract S5; the retentate was concentrated by vacuum distillation at a temperature of 55°C and a pressure of 0.7 MPa.

[0125] This embodiment provides a waste tobacco leaf extract prepared by the above preparation method. By weight, the waste tobacco leaf extract includes 40 parts of dichloromethane extract S1, 70 parts of ethyl acetate extract S2 and 15 parts of water extract, wherein the water extract is water extract S4 and water extract S5 in a mass ratio of 1:1.

[0126] Cigarette application test

[0127] This embodiment of the cigarette containing the above-mentioned extract is prepared by diluting the waste tobacco leaf extract from Examples 1-3 to 0.1% with ethanol according to the traditional flavoring method to obtain an ethanol dilution. Then, the ethanol dilution is sprayed onto the tobacco shreds at an addition rate of 200 ppm per cigarette to produce cigarettes, which are labeled as test cigarettes 1#, 2#, and 3#, respectively.

[0128] Before testing, the cigarettes were equilibrated for 48 hours at a temperature of (22±1)℃ and a relative humidity of (60±2)%. Then, they were sorted by weight (average weight ±0.02g) and draw resistance (average draw resistance ±49Pa) to select the test cigarettes that met the standards for sensory evaluation. The sensory evaluation results are shown in Table 1 below.

[0129] The sensory evaluation results in Table 1 show that, compared with the blank control cigarettes, the flavor and taste coordination of the test cigarettes No. 1, No. 2, and No. 3 were all improved, and the overall sensory quality was improved to a certain extent.

[0130] Table 1. Sensory evaluation results after applying cigarettes:

[0131]

Claims

1. A method for preparing an extract from waste tobacco leaves, characterized in that, The process includes the following steps: 1) Crushing: Waste tobacco leaves are crushed to obtain tobacco powder; 2) Enzymatic hydrolysis: The tobacco powder is treated with a compound enzyme solution to obtain an enzyme-treated tobacco powder mixture; the compound enzyme used is one or a mixture of two or more of pectinase, cellulase, laccase, and protease; 3) Organic solvent ultrasonic extraction: The enzyme-treated tobacco powder mixture obtained in step 2) is partially dehydrated to control the water content at 20%-40%, and then ultrasonically extracted sequentially with dichloromethane and ethyl acetate. After extraction, the organic solvent is removed to obtain dichloromethane extract S1 and ethyl acetate extract of the tobacco powder, respectively. Extract S2; 4) Subcritical water extract of tobacco a. Fermentation and aroma production: After sterilization of the enzyme-treated tobacco powder mixture obtained in step 2), it is inoculated with a culture broth of aroma-producing bacteria, and then fermented at room temperature for 2.5-3 days to obtain a fermented tobacco powder mixture; the aroma-producing bacteria are one or more of yeast, Bacillus subtilis, and Bacillus licheniformis. The aroma-producing bacteria are activated and cultured according to conventional methods to obtain a culture broth of aroma-producing bacteria; the inoculation amount of the aroma-producing bacteria culture broth is 1.0%-5.0% of the material mass; b. Subcritical extraction of fermented tobacco powder: The fermented tobacco powder mixture is added to water for subcritical extraction. c) Adsorption of heavy metals in the subcritical water extract: Add heavy metal adsorbent to the subcritical water extract and shake to adsorb for 1.5-3 hours, followed by solid-liquid separation; the ratio of subcritical water extract to adsorbent is 200ml:1-3g; d) Membrane separation: Filter the subcritical water extract after heavy metal adsorption through a nanofiltration membrane to obtain nanofiltration permeate and retentate; e) Concentration and molecular distillation separation: Concentrate the nanofiltration permeate to obtain a concentrated extract; perform molecular distillation on the concentrated extract to collect the light and heavy components. The light component is water extract S3, and the heavy component... The component is water extract S4; the retentate is concentrated to obtain a concentrated extract, denoted as water extract S5; in step 4), during subcritical extraction, the mass ratio of the fermented tobacco powder mixture to the water used for subcritical extraction is 1:3-7, the extraction temperature is 150-160℃, and the extraction time is 10-60 min; by weight, the waste tobacco extract includes 30-50 parts of dichloromethane extract S1, 60-80 parts of ethyl acetate extract S2, and 10-20 parts of water extract, wherein the water extract is one or more of water extract S3, water extract S4, and water extract S5.

2. The method for preparing waste tobacco leaf extract as described in claim 1, characterized in that, In step 2), the amount of compound enzyme solution used is 0.5-3% of the mass of tobacco powder, the enzyme treatment temperature is 30-50℃, the enzyme treatment humidity is 60-80%, and the enzymatic hydrolysis time is 22-30h.

3. The method for preparing waste tobacco leaf extract as described in claim 1, characterized in that, In step 3), during dichloromethane extraction, the mass ratio of tobacco powder to dichloromethane is 1:3-10, the extraction temperature is 20-40℃, and the extraction time is 0.5-3h. After dichloromethane extraction, solid-liquid separation is performed, and the solid material is further extracted with ethyl acetate at a mass ratio of tobacco powder to ethyl acetate of 1:2-5, an extraction temperature of 70-90℃, and an extraction time of 0.5-3h. During organic solvent extraction, the ultrasonic frequency is 20-40kHz.

4. The method for preparing waste tobacco leaf extract as described in claim 1, characterized in that, In step 4), the heavy metal adsorbent after shaking adsorption is washed with dilute acid, washed with water until neutral, and dried for reuse. The dilute acid is one or more combinations of nitric acid, hydrochloric acid, sulfuric acid, and aminosulfonic acid, and the concentration of the dilute acid is 0.01 to 1.0 mol / L.

5. The method for preparing waste tobacco leaf extract as described in claim 1, characterized in that, In step 4), the nanofiltration membrane is a tubular nanofiltration membrane with a pore size of 10-100 nm.

6. The method for preparing waste tobacco leaf extract as described in claim 1, characterized in that, In step 4), the molecular distillation is a two-stage molecular distillation. The light components from the first and second stage molecular distillations are combined to form the water extract S3, and the remaining heavy components are the water extract S4. The heating temperature for the first stage molecular distillation is 50–80℃, the pressure is 100–200 Pa, the feed rate is 300–600 mL / h, and the scraping speed is 200–300 rpm. The heating temperature for the second stage molecular distillation is 90–110℃, the pressure is 40–60 Pa, the feed rate is 300–600 mL / h, and the scraping speed is 200–300 rpm.

7. The waste tobacco extract prepared by any one of the preparation methods according to claims 1 to 6, characterized in that, By weight, the waste tobacco extract comprises 30-50 parts of dichloromethane extract S1, 60-80 parts of ethyl acetate extract S2, and 10-20 parts of water extract, wherein the water extract is one or more of water extract S3, water extract S4, and water extract S5.

8. The use of the waste tobacco extract according to claim 7 in cigarettes.

9. A cigarette, characterized in that, It contains the waste tobacco extract as described in claim 7.

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