WO2025120199A1

WO2025120199A1 - A method for extracting one or more alkaloids from tobacco

Info

Publication number: WO2025120199A1
Application number: PCT/EP2024/085152
Authority: WO
Inventors: Priscila BRASIL DE SOUZA CRUZ; Douglas WILLIAM MENEZES FLORES; Liliane MEDIANEIRA FAVERO PORTE; Giovana DA SILVA PINHEIRO; José MARCELINO DE SOUZA NETTO; Daniel JOSÉ DAL RI; Marcelo CAETANO ALEXANDRE MARCELO
Original assignee: Souza Cruz SA; British American Tobacco Investments Ltd IFI
Current assignee: Souza Cruz SA; British American Tobacco Investments Ltd IFI
Priority date: 2023-12-06
Filing date: 2024-12-06
Publication date: 2025-06-12
Anticipated expiration: 2026-06-06

Abstract

The present invention relates to a method for extracting one or more alkaloids from tobacco, the method comprising: (a) pre-treating tobacco by contacting tobacco with ethanol; (b) contacting the pre-treated tobacco with an extraction solvent under supercritical conditions to extract one or more alkaloids from the tobacco. The invention also relates to an extract comprising one or more alkaloids obtained or obtainable by a process according to the invention, as well as tobacco obtained or obtainable by a process according to the invention.

Description

A METHOD FOR EXTRACTING ONE OR MORE ALKALOIDS FROM TOBACCO

Technical Field

The present invention relates to a method for extracting constituents of tobacco. More specifically, the invention relates to a method comprising supercritical extraction of one or more alkaloids, such as nicotine, from tobacco.

Background

Various methods for extracting nicotine from tobacco are known. For example, conventional extraction involves mixing tobacco with solvents such as hexane and chloroform, and separating or filtering the mixture before recovering the nicotine. However, this is generally a manual process, using flammable and/or toxic substances (e.g. organic solvents), and generates effluent and wet waste in large volumes.

Extraction may be improved by using ultrasound (ultrasound assisted extraction) as a processing aid rather than chemicals. This may avoid the use of toxic substances, but this process still generates effluent and wet waste in large volumes.

Supercritical fluid extraction can alternatively be used, which avoids the use of toxic substances and the generation of waste materials.

Summary

In one aspect the present invention provides a method for extracting one or more alkaloids from tobacco, the method comprising:

(a) pre-treating tobacco by contacting tobacco with ethanol;

(b) contacting the pre-treated tobacco with an extraction solvent under supercritical conditions to extract one or more alkaloids from the tobacco.

In some aspects the one or more alkaloids which are extracted from the tobacco comprise nicotine. In another aspect the present invention provides an extract comprising one or more alkaloids (e.g. nicotine) obtained or obtainable by a process according to the invention

In a further aspect the present invention provides tobacco obtained or obtainable by a process according to the invention.

In a further aspect the present invention provides a smoking article comprising tobacco obtained or obtainable by a process according to the invention. The smoking article may be suitable for use in a combustible or non-combustible aerosol provision system.

Detailed Description

Tobacco contains well over 3000 compounds ranging from the fibrous matrix, e.g. high molecular weight polymeric compounds such as cellulose, and a variety of intermediate molecular weight constituents being mostly non-volatile, e.g. hemicellulose and lignin, and low molecular weight constituents, including aroma and flavour compounds.

Examples of tobacco components include carotenoid derivatives, alkaloids, nitrosamines, humectants, metals, non-polymeric compounds exemplified by nicotine, nornicotine, anabasine, myosmine, antabine, glycerol, propylene glycol, triethylene glycol, ammonia, nickel, lead, cadmium, chromium, arsenic, selenium, mercury, benzo[a]pyrene, nitrate, triacetin, sodium propionate, sorbic acid, and eugenol.

The present invention relates to the extraction of one or more alkaloids, such as nicotine.

The present invention provides a method for extracting one or more alkaloids from tobacco, the method comprising:

(a) pre-treating tobacco by contacting tobacco with ethanol;

The one or more alkaloids which are extracted from the tobacco generally comprise nicotine, such as at least about 50 wt% nicotine, at least about 75 wt% nicotine or at least about 90 wt% nicotine. In some embodiments, the one or more alkaloids which are extracted from the tobacco are nicotine. In some embodiments, the invention provides a method for extracting nicotine from tobacco, the method comprising:

(a) pre-treating tobacco by contacting tobacco with ethanol;

(b) contacting the pre-treated tobacco with an extraction solvent under supercritical conditions to extract nicotine from the tobacco.

As used herein, the term “alkaloids” includes any alkaloids which are obtainable from tobacco. The “alkaloids” as referred to herein may therefore alternatively be termed “tobacco alkaloids”.

T obacco

The tobacco used in the methods of the invention comprises or consists of tobacco from the stem or lamina of a tobacco plant, i.e. tobacco stem or tobacco lamina. In some embodiments, the tobacco used comprises or consists of tobacco lamina. In some embodiments, the tobacco comprises or consists of cut rag lamina tobacco. In some embodiments, the tobacco comprises or consists of threshed tobacco. Tobacco may be formed from various parts or portions of the tobacco plant as described herein. As used herein, the term “tobacco plant” means a plant of the Nicotiana species.

The term “tobacco material” may alternatively be used in place of “tobacco”.

Various parts or portions of a tobacco plant (i.e. a plant of the Nicotiana species) may be employed in the method described herein. In some embodiments, the whole plant, or substantially the whole plant, is harvested and employed as such. As used herein, the term "substantially the whole plant" means that at least about 90 wt% of the plant is harvested, such as at least about 95 wt% of the plant, such as at least about 99 wt% of the plant. Alternatively, in some embodiments, various parts or pieces of the plant are harvested or separated for further use after harvest. In some embodiments, the tobacco material is selected from the leaves, stems, stalks of the tobacco plant, or combinations thereof. The tobacco material used in the invention may therefore comprise an entire plant or any portion of a plant of the Nicotiana species.

In some embodiments the tobacco comprises Virginia tobacco and/or burley tobacco. However, other types of tobacco may also be used. In some embodiments, the tobacco comprises tobacco leaf. In some embodiments, the tobacco comprises tobacco leaf that is whole or cut tobacco leaf. In some embodiments, the tobacco comprises whole tobacco leaf. In some embodiments, the tobacco comprises cut tobacco leaf. In some embodiments, the tobacco comprises or consists of threshed tobacco.

In some embodiments, the tobacco is milled tobacco. When milled tobacco is used, it may have a particle size of from about 0.5 to about 4 mm, such as from about 1 to about 3 mm, such as about 2 mm. The size refers to the longest dimension (e.g. the diameter). In some embodiments the particle size is the average particle size, e.g. the number average particle size.

The tobacco used herein may be cured or uncured, but is generally cured tobacco.

The tobacco can optionally be treated in one or more other ways before step (b), and either before or after step (a). The tobacco can also be treated after step (b).

For example, the tobacco may be treated with chemical bases such as ammonium bicarbonate, either before or after step (a).

Alternatively, or in addition, the tobacco can be hydrated prior to supercritical extraction, either before or after step (a), but generally after (e.g. before step (b)). This can be done by, for example, taking tobacco material of a known moisture content (as established through standard analysis procedures), and placing a known weight in a receptacle with a desired amount of water. The tobacco material and water are mixed, and the receptacle may be sealed and left (e.g. for approximately 24 hours at about 4-22°C, such as at around 4°C) to allow equilibration. Moisture content can be established by testing a sample of the tobacco material using standard analysis procedures.

Alternatively, or in addition, the post- treatment tobacco can be hydrated, e.g. the tobacco left after step (b) may be hydrated. This may be done using the same procedure described above.

The water content of the tobacco should preferably not exceed a level where an aqueous slurry is formed which results in disintegration of the tobacco material. Typically, prior to extraction with a supercritical fluid (e.g. prior to step (b)), the tobacco has a moisture (water) content from about 1 wt% to about 50 wt%, from about 5 wt% to about 30 wt%, from about 10 wt% to about 15 wt%, or from about 13 wt% to about 20 wt%.

Treatment of tobacco by milling, comminution or otherwise reducing its size (e.g. to create cut rag) can lead to enhanced extraction capabilities, as a result of the increased surface area of tobacco which is exposed to the extraction solvent. This allows the extraction solvent used during step (b) of the process and/or the ethanol used in step (a) to be brought into intimate contact with the tobacco.

Thus, in some embodiments the method further comprises processing the tobacco (e.g. by milling, chopping, or comminuting) to reduce the size of the tobacco. This may be done before or after step (a), but will generally be done before step (a). In some embodiments the tobacco used in step (a) is cut rag tobacco or threshed tobacco.

In some embodiments tobacco is not treated after harvest and prior to carrying out the process of the invention, other than optionally by curing and/or milling.

The process described herein comprises removal of one or more alkaloids, such as nicotine, from tobacco. In some embodiments, the post-treatment tobacco comprises less than about 2 wt%, less than about 1.5 wt% or less than about 1 wt% nicotine, such as from about 0.1 to about 1 wt%, from about 0.2 to about 0.9 wt% or from about 0.3 to about 0.8 wt% nicotine.

As used herein, the term “post-treatment tobacco” refers to the tobacco after the extraction process has been carried out, or after step (b) of the process described herein is complete.

The post- treatment tobacco may be used in a cigarette or other smoking article. For example, the tobacco may be used in a combustible aerosol provision system (e.g. a conventional cigarette) or in a non-combustible aerosol provision system (e.g. a so-called heat-not-burn device or tobacco heated product).

It has been found that the extraction process described herein does not have a significant or negative impact on the taste of the tobacco that is treated. That is, nicotine can be extracted without significantly impacting the overall taste of the tobacco (e.g. without affecting the taste to the extent that the tobacco may not be used after treatment). As a result, the post-treatment tobacco can be used in a cigarette or other smoking article. In contrast, some other methods of extracting alkaloids such as nicotine from tobacco will have a negative impact on the overall taste of the tobacco, thereby making the tobacco unsuitable for use after treatment.

The process described herein may remove at least about 50 wt%, 60 wt%, 70 wt%, 80 wt%, 85 wt% or 90 wt% of any given alkaloid (e.g. nicotine) from the tobacco material. In some embodiments the post-treatment tobacco therefore contains less than about 50 wt%, 40 wt%, 30 wt%, 20 wt%, 15 wt% or 10 wt% of any given alkaloid (e.g. nicotine) compared to the tobacco at the start of the process.

The process described herein may also remove one or more tobacco-specific nitrosamines (TSNAs) from the tobacco material, such as nicotine-derived nitrosamine ketone (NNK) and/or N-nitrosonornicotine (NNN).

In some embodiments the post-treatment tobacco contains less than about 70 wt%, 60 wt%, or 50 wt% TSNA content compared to the tobacco at the start of the process.

In some embodiments the post-treatment tobacco contains less than about 70 wt%, 60 wt%, or 50 wt% of the NNN present in the tobacco at the start of the process.

In some embodiments the post-treatment tobacco contains less than about 70 wt%, 60 wt%, or 50 wt% of the NNK present in the tobacco at the start of the process.

Pre- treatment

Step (a) of the method described herein comprises pre-treating tobacco by contacting tobacco with ethanol.

Contacting tobacco with ethanol may comprise soaking or immersing the tobacco in ethanol. This may be done as a batch process. Alternatively, the tobacco may be contacted with ethanol as part of a continuous process. In this case the tobacco may still be immersed in ethanol, where the ethanol is constantly replaced. Alternatively, the tobacco may be, for example, continuously sprayed with ethanol.

The tobacco may be contacted with the ethanol for from about 1 , 1.5, 2, 5, 8, 10 or 12 hours, to about 48, 24, 15, 12, 8, 5, or 3 hours. In some embodiments, the tobacco is contacted with the ethanol for from about 1 to about 24 hours, such as from about 1.5 to about 20 hours. In some embodiments, the tobacco is contacted with the ethanol for from about 1.5 to about 3 hours. In other embodiments, the tobacco is contacted with the ethanol for from about 10 to about 20 hours.

The tobacco may be contacted with any suitable amount of ethanol, but generally the amount of ethanol is at least or more than the amount of tobacco (e.g. the weight ratio of tobacco to ethanol is at least 1 :1 or greater than 1 :1). The weight ratio between the tobacco and the ethanol may therefore range from about 1 :1 , 1 :2 or 1 :4 to about 1 :20, 1 :10, 1 :6 or 1 :5. In some embodiments, the weight ratio between the tobacco and the ethanol is from about 1 :1 to about 1 :10, such as from about 1 :2 to about 1 :6 or from about 1 :4 to about 1 :5.

The tobacco is contacted with ethanol at a temperature ranging from about 25 to about 75 °C, such as from about 30 to about 60 °C, from about 40 to about 60 °C or from about 45 to about 55 °C. The temperature may be controlled by adjusting the temperature of the atmosphere in which the pre-treatment takes place. Alternatively or additionally, the temperature may be controlled by adjusting the temperature of the ethanol and/or tobacco, but generally the ethanol, which is used in the pre-treatment process. In some embodiments the ethanol is preheated to the desired temperature before being used in the pre-treatment process.

The tobacco may be contacted with ethanol at any pressure. In embodiments suitable pressures include from about 1 to about 5 bar.

During the pre-treatment process the mixture of tobacco and ethanol may be stirred or otherwise agitated.

After the pre-treatment process is complete, the ethanol may be removed before the supercritical extraction takes place. The ethanol used in the pre-treatment process can be recovered and reused, making the process more environmentally friendly. Alternatively, the supercritical extraction may take place without removal of the ethanol. However, even in this case the extraction solvent used in step (b) generally does not comprise ethanol.

In embodiments, only part of the ethanol is removed before the supercritical extraction takes place. For example, from about 10 to about 90 wt% of the ethanol may be removed, such as from about 50 to about 85 wt% or from about 70 to about 80 wt%. In embodiments the majority of the ethanol (i.e. at least 50 wt%) is removed.

Any ethanol which is removed may be reserved and optionally combined with the final extract. This may be useful where the ethanol (also called the ethanol extract) contains some nicotine from the initial tobacco (i.e. where the pre-treatment process has extracted some of the nicotine from the tobacco). By combining this ethanol extract with the final (supercritical fluid) extract, the nicotine yield and/or extraction efficiency of the overall process can be maximised. Either or both of the extracts may be concentrated prior to being combined. Alternatively or additionally, the final extract can be concentrated.

Supercritical extraction

Step (b) of the method of the invention comprises contacting the pre-treated tobacco with an extraction solvent under supercritical conditions to extract one or more alkaloids from the tobacco.

As used herein, the term “pre-treated tobacco” means tobacco that has undergone the pretreatment step with ethanol as described herein, i.e. the tobacco formed after step (a) of the process described herein. Put another way, “pre-treated tobacco” is the product of step (a) of the process described herein.

As discussed above, the pre-treated tobacco which is contacted with an extraction solvent under supercritical conditions may still comprise a portion of the ethanol used in step (a), i.e. where not all of the ethanol is removed after step (a). In some embodiments, the pre-treated tobacco still includes from about 10 to about 90 wt%, from about 50 to about 35 wt% or from about 20 to about 30 wt% of the ethanol added in step (a).

Examples of extraction fluids or solvents which can used in the supercritical extraction (i.e. step (b) of the process) include, but are not limited to, carbon dioxide, sulphur hexafluoride, nitrous oxide, halogenated hydrocarbons having up to four carbon atoms such as CF4, CHF3, CCIF3, CBrF₃, CF₂=CH₂, CF₃CF₂CF₃, CHCIF₂, CCI₂F₂, CHCI₂F, CCI3F, CBrF₃, CFCI=CF₂, CH3CF3, octafluorocyclobutane, and hydrocarbons (optionally substituted with oxygen or halogen moieties) including up to seven carbon atoms such as propane, butane, pentane, hexane, cyclohexane, toluene, ethanol, acetone, methyl acetate, diethyl ether, dichloromethane, carbon tetrachloride, as well as combinations thereof. Other useful fluids include argon.

In preferred embodiments, the extraction solvent used herein is not a toxic, flammable or environmentally-unfriendly extraction solvent. Accordingly, in some embodiments, the extraction solvent is not methanol or hexane. In preferred embodiments, the extraction solvent comprises or is carbon dioxide (CO2).

In some embodiments, the extraction solvent does not comprise ethanol.

As used herein, the term “extraction solvent” is used interchangeably with “supercritical fluid”, in particular when the extraction solvent is present under supercritical conditions. Thus, step (b) may comprise contacting the pre-treated tobacco with a supercritical fluid to extract one or more alkaloids from the tobacco.

The pressure applied during extraction can be any pressure at or above the critical pressure of the extraction solvent or supercritical fluid employed in the method. For carbon dioxide, the pressure can be as low as around 7.0 MPa, but is generally is at least about 7.38 or 7.382 MPa.

The pressure applied during extraction (i.e. in step (b)) may range from about 1 , 7, 7.38, 7.382, 10, 15, 20 or 25 MPa to about 60, 50, 40 or 35 MPa. In some embodiments, the pressure ranges from about 1 to about 60 MPa, such as from about 10 to about 50 MPa, or from about 20 to about 35 MPa.

In some embodiments the extraction solvent is carbon dioxide and the pressure ranges from about 7.0 to about 60 MPa, from about 7.38 to about 50 MPa, from about 10 to about 40 MPa or from about 20 to about 35 MPa.

The temperature during extraction (i.e. in step (b)) may range from about 25°C to about 90°C, such as from about 30°C to about 70°C, or from about 40°C to about 60°C.

When using carbon dioxide as the supercritical fluid, a temperature during supercritical extraction of from about 40°C to about 60°C and a pressure of from about 10 MPa to about 30 MPa is preferred. When using carbon dioxide as the supercritical fluid, a temperature during supercritical extraction of about 50°C and a pressure of about 30 MPa (300 bar) is particularly preferred.

In some embodiments, supercritical extraction is performed using about 70 kg of extraction solvent (e.g. carbon dioxide) as the supercritical fluid per kg of a tobacco material.

In some embodiments, supercritical extraction is performed using a flow rate of extraction solvent (e.g. carbon dioxide) of from about 0.6, 1 , 3, 5, 7, 9 or 10 kg/hr to about 30, 25, 20, 15 or 12 kg/hr. In embodiments the flow rate may be up to about 2500 kg/hr, such as up to about 2000 kg/hr or up to about 1800 kg/hr.

The flow rate may also be measured in kg/min, and may range from about 0.01 to about 0.5 kg/min, such as from about 0.01 , 0.02, 0.05, 0.08, 0.12, 0.15 kg/min to about 0.5, 0.4, 0.3, 0.25 or 0.2 kg/min. In embodiments the flow rate may be up to about 40 kg/hr, such as up to about 35 kg/hr or up to about 30 kg/min.

In some embodiments, supercritical extraction is performed using a flow rate of extraction solvent (e.g. carbon dioxide) of from about 1 to about 30 kg/hr, such as from about 5 to about 20 kg/hr or from about 7 to about 12 kg/hr. In some embodiments supercritical extraction is performed using a flow rate of extraction solvent (e.g. carbon dioxide) of from about 1000 to about 2500 kg/hr, such as from about 1500 to about 1800 kg/hr.

In some embodiments, supercritical extraction is performed using a flow rate of extraction solvent (e.g. carbon dioxide) of from about 0.01 to about 0.5 kg/min, such as from about 0.08 to about 0.3 kg/min or from about 0.12 to about 0.2 kg/min. In some embodiments supercritical extraction is performed using a flow rate of extraction solvent (e.g. carbon dioxide) of from about 15 to about 40 kg/min, such as from about 25 to about 30 kg/min.

As the skilled person would appreciate, higher flow rates (e.g. from about 1000 to about 2500 kg/hr, such as from about 1500 to about 1800 kg/hr, or from about 15 to about 40 kg/min, such as from about 25 to about 30 kg/min) may be more useful in an industrial process and/or where the chamber in which the extraction is performed is large (e.g. from about 200 to about 400 L, such as about 300 L). Suitable amounts of tobacco to include in such chambers may range from about 100 to about 300 kg, such as about 200 kg. The duration of contacting the tobacco material with the supercritical fluid can vary, and is suitably of such a length so as to permit the removal of at least about 20 wt% of the solutes from the tobacco. The duration of the extraction is influenced by the type of supercritical fluid used, the type of tobacco used, the shape of the tobacco, the extraction conditions used and the type of extraction vessel. Typically, the tobacco is in contact with the supercritical fluid for at least about 5 minutes, such as at least about 20 minutes or at least about 60 minutes. In some embodiments the tobacco is in contact with the supercritical fluid for from about 5 to about 360 minutes, such as from about 5 to about 300 minutes, from about 20 to about 200 minutes or from about 60 to about 180 minutes.

The extraction fluid used in the extraction process can be recovered and reused, making the process more environmentally friendly.

A product of step (b) is an extract (specifically a tobacco extract) containing one or more alkaloids, such as nicotine. Another product is the post-treatment tobacco which, as described herein, has a lower alkaloid (e.g. nicotine) content than the tobacco at the start of the process. These products may be separated by suitable techniques known to the skilled person.

In some embodiments, the extract formed from step (b) comprises from about 3 wt%, 5 wt%, 8 wt%, 10 wt% or 15 wt% to about 40 wt%, 35 wt%, 30 wt%, 25 wt% or 20 wt% of one or more alkaloids, such as nicotine. In some embodiments the extract formed from step (b) comprises from about 5 wt to about 40 wt%, such as from about 10 wt% to about 30 wt%, or from about 15 wt% to about or 25 wt% of one or more alkaloids, such as nicotine.

The extract may further comprise other components derived from the tobacco. In some embodiments the extract further comprises tobacco-specific nitrosamines (TSNAs), polyphenols, sugars, and/or fatty acids.

The post-treatment tobacco formed from the process described herein may contain less than about 2 wt% alkaloids such as nicotine, such as less than about 1.5 wt%, less than about 1 wt% or less than about 0.8 wt%. In some embodiments, the post-treatment tobacco comprises from about 0.1 to about 1 wt% or from about 0.3 to about 0.8 wt% alkaloids, such as nicotine. The post-treatment tobacco formed from the process described herein may contain less water than the tobacco at the start of the process. For example, the water content of the posttreatment tobacco may be from about 20 to about 70 wt%, such as from about 30 to about 50 wt% compared with the water content of the tobacco at the start of the process. For example, the water content of the tobacco at the start of the process may range from about 10 to about 20 wt%, such as from about 14 to about 18 wt%. The water content of the post-treatment tobacco may range from about 3 to about 8 wt%, such as from about 4 to about 7 wt%.

The post-treatment tobacco may, in some embodiments, be subjected to a further extraction process (e.g. step (b) may be repeated using the post-treatment tobacco as the starting material). Step (b) may be repeated a number of times (e.g. a total of 2, 3 or 4 times). In this way the content of alkaloids in the tobacco may be further reduced, for example to form tobacco containing no or essentially no alkaloids such as nicotine. For example tobacco may be formed which contains less than about 2 wt%, less than about 1 wt%, less than about 0.5 wt% or less than about 0.1 wt% alkaloids, such as nicotine.

As described above, the post- treatment tobacco may be hydrated to increase the water content, if desired. For example, the water content of the post-treatment tobacco may be increased to at least about 80 wt%, at least about 90 wt%, at least about 95 wt%, at least about 99 wt% or at least about 100 wt% of the water content of the tobacco at the start of the process.

Cleaning of the extraction machinery following supercritical extraction may be achieved by performing one or more "dry runs", by passing a supercritical solvent through the machinery in the absence of any tobacco material. Embodiments of the present invention which utilize a non-toxic, non-flammable and/or environmentally-friendly extraction supercritical fluid, such as carbon dioxide (CO2), facilitate the cleaning process.

Other aspects

In a further aspect of the present invention there is provided an extract comprising one or more alkaloids (e.g. nicotine) obtained or obtainable by a process according to the invention.

In some embodiments the extract comprises from about 5 wt%, 8 wt%, 10 wt%, 15wt% or 16 wt% to about 40 wt%, 35 wt%, 30 wt%, 25 wt% or 20 wt% of one or more alkaloids, such as nicotine. In some embodiments the extract formed from step (b) comprises from about 5 wt to about 40 wt%, such as from about 10 wt% to about 30 wt%, or from about 15 wt% to about or 25 wt% of one or more alkaloids, such as nicotine.

As used herein, the term “extract” refers to the extract formed by the process of the invention which has not undergone further purification or other processing. This extract is therefore distinct to a purified extract or an isolated compound or mixture of compounds which may be formed from an extract. In some embodiments the extract comprises ethanol. In some embodiments the extract does not comprise chloroform, hexane or water. In some embodiments the extract does not comprise any other solvents apart from ethanol.

In a further aspect of the present invention there is provided tobacco obtained or obtainable by a process according to the invention. That is, tobacco that has been formed from the claimed process. Such tobacco (referred to herein as post-treatment tobacco) will have reduced levels of alkaloids, such as nicotine, compared to corresponding tobacco that has not been subjected to the supercritical extraction process described herein. The tobacco will also have reduced levels of alkaloids, such as nicotine, compared to corresponding tobacco that has been subjected to a supercritical extraction process but without the pre-treatment step (step (a)) described herein.

The post-treatment tobacco may contain less than about 2 wt% alkaloids such as nicotine, such as less than about 1 .5 wt%, less than about 1 wt% less than about 0.9 wt% or less than about 0.8 wt%. In some embodiments, the post-treatment tobacco comprises from about 0.1 to about 1 wt%, from about 0.2 to about 0.9 wt% or from about 0.3 to about 0.8 wt% alkaloids such as nicotine.

In some embodiments the post-treatment tobacco contains less than about 70 wt%, 60 wt%, or 50 wt% of the NNK present in the tobacco at the start of the process. The water content of the post-treatment tobacco may range from about 3 to about 8 wt%, such as from about 4 to about 7 wt%.

In a further aspect of the present invention there is provided a smoking article comprising tobacco obtained or obtainable by a process according to the invention. The smoking article may be suitable for use in a combustible or non-combustible aerosol provision system.

Before being used in a smoking article water may be added to the tobacco to increase the water content, for example to about the same as the water content of the tobacco prior to treatment. For example, water may be added to the post-treatment tobacco to increase the water content to from about 10 to about 20 wt%, such as from about 14 to about 18 wt%.

Also provided herein is an apparatus for extracting constituents from tobacco, comprising a means for pre- treating tobacco by contacting tobacco with ethanol, and a means for contacting said pre-treated tobacco with an extraction solvent under supercritical conditions sufficient to extract one or more alkaloids from the tobacco. This may form an extract comprising one or more alkaloids, and a raffinate, and the apparatus may further comprise a means for separating the extract from the raffinate.

Suitable apparatuses which permit operation under conditions in which an extraction solvent is present in the supercritical state is known in the art, and typically comprises one or more pressure-resistant containers and associated plant components.

In certain embodiments, the apparatus comprises an extraction tank, into which a supercritical fluid, such as supercritical carbon dioxide, is introduced from a working tank via one or more pumps. The carbon dioxide may be conducted through a heat exchanger to bring it to process temperature. The carbon dioxide is then brought into intimate contact with the pre-treated tobacco. This may be carried out by conducting the supercritical fluid through one or more containers connected in parallel, which contain the pre-treated tobacco. Means of separating the extract from the raffinate are known in the art. In certain embodiments, the separation means comprises a buffer tank or separator vessel, which contains a trap for basic constituents, thereby removing particulate and/or certain dissolved or suspended matter. Examples

Nicotine was extracted from tobacco using three different supercritical extraction methods, as described below in Examples 1-3.

Example 1 (comparative)

Firstly, supercritical extraction using CO2 was performed without a pre-treatment step using the conditions set out in the table below. This process involved subjecting 700 g of flue cured tobacco to supercritical extraction using CO2 under the conditions shown in Table 1 below at a flow rate of CO2 of 10 kg/hr and an extraction time of 7-8 hours. The nicotine content of the tobacco prior to treatment was 3.4 wt%.

The results are shown in Table 1 below.

Table 1 - extraction using CO2 without a pre-treatment step

The extract yield is the mass of extract divided by the initial mass of tobacco, expressed as a percentage.

The nicotine extraction yield is calculated according to Equation 1:

Nicf

Nicotine extraction yield = 100 [1 — - ] Equation 1

where NiCf is the nicotine content of the post-treatment (or final) tobacco, and Niq is the nicotine content of the untreated (or initial) tobacco. Where the process involves a pretreatment step (i.e. step (a) of the process described herein), the initial nicotine content is measured before this process is carried out.

The nicotine content of the tobacco before and after treatment was measured by GC Liquid with FID Detector.

Example 2 (comparative)

Secondly, supercritical extraction using CO2 was performed without a pre-treatment step but in the presence of ethanol as a co-solvent using the conditions and parameters set out in Tables 2 and 3 below. Thus, in this process the extraction solvent comprised CO2 and ethanol.

This process involved subjecting 700 g of the same flue cured tobacco as used in Example 1 to a supercritical extraction using an extraction solvent comprising CO2 and ethanol as a cosolvent in the amounts set out in T able 2 below. Extraction was performed under the conditions shown in Table 3 below at a flow rate of CO2 of 10 kg/hr and an extraction time of 7-8 hours. The nicotine content of the tobacco prior to treatment was 3.4 wt%.

Table 2 - Amount of ethanol in the extraction solvent

The results are shown in Table 3 below. Table 3 - extraction using CO2 without a pre-treatment step in the presence of ethanol as a co-solvent

Example 3

Thirdly, supercritical extraction using CO2 was performed after pre-treatment of the tobacco with ethanol. For this process threshed tobacco was placed into an extraction vessel (5L), which was then filled with ethanol and left at 50°C. The details of the tobacco used and the pre-treatment process are set out in Table 4 below. The tobacco used in run SCO-011 was the same as used in Examples 1 and 2.

Table 4 - Pre-treatment process

Supercritical extraction using CO2 was then performed using the conditions set out in Table 5 below, with a CO2 flow rate of 10 kg/hr and an extraction time of 145 minutes. The ethanol was not drained before carrying out the supercritical extraction.

The results are shown in Table 5 below.

Table 5 - extraction using CO2 with a pre-treatment step

As is apparent from the results set out above, by including the pre-treatment step of the present invention (i.e. step (a)) both the extraction yield and the nicotine extraction yield were increased. That is, the extraction yield and the nicotine extraction yield were higher in Example 3 than Examples 1 and 2.

Thus, by utilising the pre-treatment step of the present invention it was possible to increase the amount of extract produced and the percentage of nicotine extracted from the tobacco. This is shown clearly in the average results set out in Table 6 below. In Table 6 the average results for the runs in each example have been given (e.g. for Example 3 the averages given in Table 6 are the averages of the results for SCO-011 , SCO-014 and SCO-015).

Table 6 - Average results from Examples 1-3

The process of the present invention is therefore capable of extracting a greater percentage of nicotine from tobacco than when alternative extraction processes are used. This can allow for the formation of tobacco having a lower nicotine content, and/or for the more efficient and/or faster production of tobacco having a low nicotine content.

Example 4

Approximately 150 g of threshed tobacco was pre-treated with ethanol by soaking the tobacco in ethanol in a 1 L tank at 50°C for 2 hours, using a weight ratio of tobacco to ethanol of 1 :6.

75 wt% of the ethanol was then drained and reserved (ethanol fraction). Supercritical extraction using CO2 was then performed on the pre-treated tobacco (including 25 wt% of the original ethanol) with a CO2 flow rate of 1 kg/hour, a pressure of 30 MPa, a temperature of 50°C and an extraction time of 120 minutes. The extract (tobacco fraction) was then collected and combined with the ethanol fraction, and the overall nicotine extraction efficiency calculated as 90 %.

Claims

1. A method for extracting one or more alkaloids from tobacco, the method comprising:

(a) pre-treating tobacco by contacting tobacco with ethanol;

2. The method of claim 1 , wherein the one or more alkaloids comprise nicotine.

3. The method of claim 1 , wherein the one or more alkaloids is nicotine.

4. The method of any preceding claim, wherein the tobacco is cured.

5. The method of any preceding claim, wherein the tobacco is threshed tobacco.

6. The method of any preceding claim, wherein the tobacco after treatment has a nicotine content of less than about 2 wt% nicotine, such as less than about 1.5 wt% nicotine or less than about 1 wt% nicotine.

7. The method of any preceding claim, wherein the process removes at least about 50 wt% of the one or more alkaloids from the tobacco, such as at least about 60 wt%, at least about 70 wt%, at least about 80 wt%, at least about 85 wt% or at least about 90 wt%.

8. The method of any preceding claim, wherein the process removes at least about 60 wt% of the nicotine from the tobacco, such as at least about 70 wt%, at least about 80 wt%, at least about 85 wt% or at least about 90 wt%.

9. The method of any preceding claim, wherein step (a) comprises contacting tobacco with ethanol for from about 1 to about 24 hours, such as from about 1.5 to about 20 hours.

10. The method of any preceding claim, wherein step (a) comprises soaking or immersing the tobacco in ethanol.

11. The method of any preceding claim, wherein the weight ratio of tobacco to ethanol in step (a) is from about 1:1 to about 1:10, such as from about 1:2 to about 1:6 or from about 1:4 to about 1:5.

12. The method of any preceding claim, wherein step (a) takes place at a temperature of from about 25 to about 75 °C, such as from about 30 to about 60 °C, from about 40 to about 60 °C or from about 45 to about 55 °C.

13. The method of any preceding claim, wherein the extraction solvent comprises carbon dioxide, optionally wherein the extraction solvent does not comprise ethanol.

14. The method of any preceding claim, wherein the supercritical conditions comprise a temperature of from about 25°C to about 90°C, such as from about 30°C to about 70°C, or from about 40°C to about 60°C.

15. The method of any preceding claim, wherein the supercritical conditions comprise a pressure of from about 1 to about 60 MPa, such as from about 10 to about 50 MPa or from about 20 to about 35 MPa.

16. The method of any preceding claim, wherein the supercritical conditions comprise a flow rate of extraction solvent of from about 0.6 to about 30 kg/hr, such as from about 5 to about 20 kg/hr or from about 7 to about 12 kg/hr.

17. The method of any preceding claim, wherein after step (b) the tobacco contains less than about 50 wt% of the one or more alkaloids compared to the tobacco at the start of the process.

18. The method of any preceding claim, wherein the extract formed by the process contains from about 5 to about 40 wt% of the one or more alkaloids, such as from about 10 to about 30 wt% or from about 15 to about 25 wt%.

19. A tobacco extract formed by the process of any preceding claim.

20. The tobacco extract of claim 19, wherein the extract comprises from about 5 to about 40 wt% of one or more alkaloids, such as from about 10 to about 30 wt% or from about 15 to about 25 wt%.

21. The tobacco extract of claim 19 or 20, wherein the one or more alkaloids is nicotine, optionally wherein the extract comprises from about 15 to about 25 wt% nicotine.

22. The tobacco extract of any of claims 19-21 , wherein the extract comprises ethanol, optionally wherein the extract does not comprise any other solvents.

23. Tobacco formed using a process of any of claims 1-18.

24. The tobacco of claim 23, which comprises less than about 2 wt% nicotine, such as less than about 1.5 wt% nicotine or less than about 1 wt% nicotine.

25. A smoking article comprising the tobacco of claim 23 or 24.