An improved method for producing liquid tobacco extract

Abstract

A method for producing a liquid tobacco extract, the method comprising the steps of: preparing a tobacco starting material; applying an alkaline solution to the tobacco starting material to produce an alkalized tobacco material; heating the alkalized tobacco material in an extraction chamber at an extraction temperature between 100°C and 160°C for at least 30 minutes, wherein the alkalized tobacco material is heated in an inert gas stream or in a combined stream of inert gas and water or steam, and wherein the water content of the alkalized tobacco material is between 10% by weight and 20% by weight prior to the heating step; condensing volatile compounds released from the tobacco starting material during the heating step and collecting the condensate of the volatile compounds; and forming a liquid tobacco extract comprising the condensate of the volatile compounds.

Description

[0001] The present invention relates to a method for producing a liquid tobacco extract and the liquid tobacco extract produced by such a method.

[0002] Aerosol generation systems for delivering aerosols to users are known, comprising an atomizer configured to generate an inhalable aerosol from a liquid formulation, such as a liquid nicotine formulation. Some known aerosol generation systems include thermal atomizers, such as electric heaters, configured to heat and vaporize the liquid formulation to generate an aerosol. A popular type of electrically heated aerosol generation system is the electronic cigarette. Other known aerosol generation systems include non-thermal atomizers configured to generate an aerosol from a liquid formulation using, for example, impingement jet, ultrasonic, or vibrating mesh technologies.

[0003] Several methods are known for producing liquid tobacco extracts from tobacco materials. Liquid tobacco extracts can be produced through a high-temperature extraction process, in which nicotine and other volatile flavor compounds are extracted from tobacco materials and collected in a suitable solvent to form a natural liquid tobacco extract.

[0004] Soaking methods are also known, in which tobacco material is kept suspended in an extraction liquid for weeks or even months. The resulting pulp is then filtered, and the collected liquid phase can be used to manufacture vaporizable liquid formulations. In one such method—the so-called “cold soaking method”—there is typically no way to control the extraction conditions (e.g., temperature and pressure). In a variant of the soaking method, as described, for example, in US 2012 / 192880, the pulp is heated to 100 degrees Celsius or higher.

[0005] The liquid phase collected during pulp filtration, representing the main products of the soaking process, is highly diluted and tends to have a low content of non-polar tobacco flavor species. Furthermore, the liquid phase is typically almost or completely free of nicotine. Therefore, the liquid extract obtained by the soaking method usually needs to be supplemented with additional components, such as nicotine salts and glycerin, before being used in vaporizable liquid formulations.

[0006] Alternative methods are known in which tobacco material is substantially boiled in water for several hours or even days to form a vapor phase, and the distillate obtained by condensation of the vapor phase is continuously collected in a container. Over time, an oily waxy layer containing a high proportion of nonpolar compounds accumulates on the surface of the distillate.

[0007] On the other hand, the aqueous fraction containing the accumulated wax layer and nicotine and other water-soluble compounds is recycled back to the boiler. Optionally, a non-polar solubilizer may be fed into the boiler along with the aqueous fraction to increase the extraction yield. The wax phase is then collected, ultimately forming the main product of this hydrodistillation process. This product is often referred to as "tobacco oil" and contains a high proportion of non-polar compounds found in tobacco, such as fatty acids and neophytadiene. Tobacco oil obtained by such a method typically does not contain nicotine.

[0008] Extraction processes involving the use of volatile, nonpolar solvents are also known for subjecting tobacco materials to extraction. Examples of suitable solvents include cyclic or acyclic short alkanes, as well as chlorinated solvents such as dichloromethane. In such a process, excess solvent can be evaporated by controlled heating under vacuum. Typically, this is carried out in the presence of ethanol, which has a higher boiling point than the extraction solvent, making even trace amounts of the extraction solvent detectable.

[0009] The main product of such a solvent-assisted extraction process is often referred to as "tobacco absolute" and may contain trace amounts of ethanol. It is a waxy product and a highly concentrated mixture of most nonpolar compounds that can be extracted with specific solvents, typically including nicotine, which is usually present in relatively high concentrations.

[0010] An alternative extraction process involves contacting tobacco material with a solvent under supercritical conditions, such as supercritical carbon dioxide. One such process is disclosed in US 2013 / 160777 and relies on the principle that volatile substances within the feed material in contact with a supercritical fluid can be partitioned into the supercritical phase. After the dissolution of any soluble material, the supercritical fluid containing the dissolved substances can be removed, and the dissolved components of the feed material can be separated from the supercritical fluid. The main product of a supercritical extraction process is essentially similar to "tobacco pure oil" produced by solvent-assisted extraction processes operating at lower temperatures and pressures, containing no residual solvent, typically high levels of waxy nonpolar compounds, and containing nicotine, usually present in relatively high concentrations.

[0011] However, all tobacco extracts that can be obtained by methods known in the art tend to have very low levels, if any, of compounds associated with the flavor of heated tobacco, such as dimethylhydroxyfuranone.

[0012] Generally, as discussed above, liquid tobacco extracts obtained through such known extraction processes may have low nicotine levels. Furthermore, liquid tobacco extracts obtained through such extraction processes may have low levels of flavor species and low flavor species diversity. Liquid tobacco extracts obtained through such extraction processes may also have high levels of undesirable compounds. Typically, the concentrations of nicotine, flavor compounds, and undesirable compounds obtained through this extraction process can be significantly influenced by one or more types of tobacco used as starting material.

[0013] The object of this invention is to mitigate one or more drawbacks of liquid tobacco extracts obtained by known processes. Specifically, it is desirable to provide a method for producing novel and improved liquid tobacco extracts. In particular, it is desirable to provide such a method for producing such liquid tobacco extracts that can be performed more efficiently than existing processes.

[0014] This disclosure relates to a method for producing a liquid tobacco extract from tobacco material. The method may include the step of preparing the tobacco material. An alkaline solution may be applied to the tobacco material to produce an alkalized tobacco material. The alkalized tobacco material may be heated at an extraction temperature between about 100°C and about 160°C. Heating may be performed for at least 30 minutes. The alkalized tobacco material may be heated in an inert gas stream or in a combined stream of inert gas and water or steam. The method may further include the step of condensing volatile compounds released from the alkalized tobacco material during the heating step and collecting the condensate of the volatile compounds. The method may further include the step of forming a liquid tobacco extract comprising the condensate of the volatile compounds.

[0015] This disclosure further relates to an alternative method for producing a liquid tobacco extract from tobacco material. The method may include a step of preparing the tobacco material. The tobacco material may be heated at an extraction temperature between 100°C and 160°C for at least 90 minutes. The method may further include a step of collecting volatile compounds released from the tobacco starting material during the heating step and forming a first liquid tobacco extract comprising the collected volatile compounds from the tobacco starting material. The method may further include a step of applying an alkaline solution to the residual tobacco material from the heating step to produce an alkalized tobacco material. The alkalized tobacco material may be heated at an extraction temperature between 100°C and 160°C. The method may further include a step of collecting volatile compounds released from the alkalized tobacco material during the heating step and forming a second liquid tobacco extract comprising the collected volatile compounds from the alkalized tobacco material.

[0016] According to a first aspect of the present invention, a method for producing a liquid tobacco extract is provided, the method comprising the steps of: preparing a tobacco material; applying an alkaline solution to a tobacco starting material to produce an alkalized tobacco material; heating the alkalized tobacco material at an extraction temperature between about 100 degrees Celsius and about 160 degrees Celsius for at least about 30 minutes, wherein the alkalized tobacco material is heated in an inert gas stream or in a combined stream of inert gas and water or steam; condensing volatile compounds released from the alkalized tobacco material during the heating step and collecting the condensate of the volatile compounds; and forming a liquid tobacco extract comprising the condensate of the volatile compounds.

[0017] According to a second aspect of the present invention, a method for producing a liquid tobacco extract is provided, the method comprising the steps of: preparing a tobacco material; heating the tobacco material at an extraction temperature of 100°C to 160°C for at least 90 minutes; collecting volatile compounds released from the tobacco starting material during the heating step; forming a first liquid tobacco extract comprising the collected volatile compounds from the tobacco starting material; applying an alkaline solution to the residual tobacco material from the heating step to produce an alkalized tobacco material; heating the alkalized tobacco material in an extraction chamber at an extraction temperature between 100°C and 160°C; collecting volatile compounds released from the alkalized tobacco material during the heating step; and forming a second liquid tobacco extract comprising the collected volatile compounds from the alkalized tobacco material.

[0018] According to the present invention, a liquid tobacco extract produced by the method of the present invention as defined above is also provided.

[0019] As used herein with reference to the invention, the term "liquid tobacco extract" describes the direct product of an extraction process performed on tobacco material. Therefore, tobacco extracts typically comprise a mixture of natural components separated, removed, or derived from natural tobacco material using tobacco extraction processing conditions and techniques. Thus, in such a process, the extracted tobacco components are removed from the natural tobacco material and separated from unextracted tobacco components. According to the invention, the extraction process for producing a liquid tobacco extract includes heating the tobacco material under specific heating conditions and collecting the volatile compounds generated. Therefore, the liquid tobacco extract consists of a mixture of natural tobacco components derived from the tobacco material and extracted or formed during the extraction process, typically combined with one or more materials other than the tobacco material, such as a non-aqueous extraction solvent used in the extraction process. As will be described in more detail below, absorption techniques can be used to collect volatile compounds released from the starting tobacco material, wherein said volatile compounds are trapped in a non-aqueous extraction solvent. For example, an inert gas stream containing volatile compounds can be directed into a container of a non-aqueous extraction solvent. The non-aqueous extraction solvent is preferably an aerosol forming agent.

[0020] This invention provides a novel extraction method incorporating an alkaline treatment step, during which an alkaline solution is applied to tobacco material. According to a first aspect of the invention, the tobacco material may undergo an alkaline treatment step prior to a heating step. It has been found that incorporating an alkaline treatment step prior to heating, combined with defined heating conditions, provides a very significant increase in nicotine yield. For example, in some cases it has been found that the inclusion of an alkaline treatment step increases the nicotine extraction yield by up to 900% compared to equivalent extractions performed without an alkaline treatment step. It has also been found that incorporating an alkaline treatment step prior to heating produces a favorable change in the balance of flavor compounds in the resulting extract. Specifically, the yield of certain desired flavor compounds, such as certain pyrazine compounds, can be increased. Advantageously, these increases in the yield of nicotine and other flavor compounds are provided, while there is no increase in the yield of TSNA. Overall, the ratio of desired to undesired compounds in the extract can therefore be increased.

[0021] Without being bound by theory, it is believed that alkaline treatment of tobacco materials promotes the conversion of nicotine from a protonated form to a free alkaline form, which in turn helps to more efficiently convert nicotine into the gas phase during the heating step.

[0022] In an alternative method according to a second aspect of the invention, the residual tobacco material remaining after the heating step is subjected to an alkalization treatment step. The alkalized tobacco material is then subjected to a second heating step to extract additional volatile compounds, which may optionally be added to the volatile compounds collected from the first heating step. Thus, such a method involves performing two separate heating steps on the same batch or sample of tobacco material.

[0023] "Residual tobacco material" refers to the tobacco material remaining after extraction during the first heating step as defined above, wherein the tobacco material is heated to a temperature between 100 and 160 degrees Celsius. Therefore, the residual tobacco material is the same tobacco material used in the heating step, but from which a certain proportion of volatile compounds have been removed due to the extraction.

[0024] It has been found that including an alkaline treatment step in the extraction method after the first heating step further optimizes the composition of the liquid tobacco extract produced by the extraction method. Alkaline treatment of the residual tobacco material before the second extraction allows the second heating step to extract a higher proportion of nicotine from the tobacco material, thereby maximizing the overall level of extracted nicotine. The reason for this is the same as that described above regarding other embodiments of the invention.

[0025] The extraction of additional nicotine is carried out in a separate step following the first extraction of volatile compounds, thus ensuring that the first extraction is unaffected by the alkaline treatment step. This allows the first extraction to be optimized for the yield of desired flavor compounds from the tobacco material, while the second extraction advantageously increases the overall nicotine yield.

[0026] The alkaline treatment step can advantageously be carried out within existing extraction equipment, thereby minimizing the overall impact of the alkaline treatment step on the efficiency of the extraction process. The alkaline treatment step can be performed using readily available equipment that can be incorporated into existing extraction equipment without significant modifications.

[0027] In addition to the increased nicotine yield due to the inclusion of an alkaline treatment step, the extraction method of the present invention also utilizes specific extraction conditions to advantageously provide an improved liquid tobacco extract with a significantly improved balance between desired and undesired compounds. Specifically, the extraction method of the present invention provides a liquid tobacco extract from tobacco material with the maximum ratio of desired to undesired compounds. For example, the use of specific combinations of extraction temperatures and times, as defined, enables optimization of nicotine compound levels while minimizing levels of undesired compounds such as furans, carbonyl compounds, phenols, and TSNAs.

[0028] The inventors of this invention have discovered that, compared to the existing extraction processes discussed above, the method according to the invention advantageously provides a liquid tobacco extract having a significantly higher content of compounds associated with the flavor of heated tobacco, such as dimethylhydroxyfuranone. These compounds are substantially absent or present in trace amounts in tobacco extracts obtained by immersion processes, which are also typically almost or completely free of nicotine. These compounds are also typically absent or present in trace amounts in tobacco extracts obtained using solvents, including those obtained under supercritical conditions. Similarly, tobacco essential oils obtained by distillation processes typically also have very low—if any—contents of such compounds associated with the flavor of heated tobacco.

[0029] The liquid tobacco extract obtained by the method according to the invention exhibits a significant compositional difference compared to tobacco extracts obtained by existing extraction processes and can be used as an e-liquid or for the preparation of e-liquids that, when heated, generate an aerosol with a different composition and flavor profile than currently available e-liquids. In particular, the liquid tobacco extract obtained by the method according to the invention can be used to generate an aerosol that provides the flavor of heated tobacco, which is more similar to the aerosol generated by conventional cigarettes or when tobacco is heated in a heated, non-combustion device than the aerosols available from existing liquid nicotine compositions.

[0030] The extraction method of this invention enables the production of liquid tobacco extracts with optimized nicotine and flavor compound levels without the need for post-extraction addition of such compounds. Therefore, the resulting liquid tobacco extract can be used directly to provide nicotine compositions. The resulting liquid tobacco extract can also be modified through one or more further processing steps or mixed with one or more ingredients to form nicotine compositions. These nicotine compositions can be used in electronic cigarettes or other aerosol generation systems.

[0031] As described above, aerosol generation systems for delivering aerosols to users are known, the systems including atomizers configured to generate inhalable aerosols from liquid formulations such as liquid nicotine compositions.

[0032] The method for producing liquid tobacco extract of the present invention is effective for all types and grades of tobacco, including burley tobacco, fire-tube flue-cured tobacco, and aromatic tobacco. The method steps can be easily adjusted to provide a consistent liquid tobacco extract for blends of various tobacco types. The extraction method is also suitable for various forms of tobacco material.

[0033] As described above, the method of the present invention incorporates an alkaline treatment step, which is performed on the tobacco material or on residual tobacco material prior to heating. In either case, the alkaline treatment step may be performed in the same manner, and unless otherwise stated, any reference below to the alkaline treatment of tobacco material should also be considered applicable to the alkaline treatment of residual tobacco material.

[0034] Alkaline treatment is performed by applying an alkaline solution to the tobacco material to alkalize it. Preferably, the alkaline solution is sprayed onto the tobacco material so that it is distributed as evenly as possible throughout the material.

[0035] In the method according to the first aspect of the invention, the tobacco material may be applied an alkaline solution in an extraction chamber in which the heating step is performed or in a separate device.

[0036] In a method according to a second aspect of the invention for alkaline treatment of residual tobacco material from a first heating step, an alkaline solution may be applied to the residual tobacco material in an extraction chamber where the first heating step has occurred. Alternatively, the residual tobacco material may be collected from the extraction chamber where the first heating step has occurred, and the alkaline solution may be applied to the residual tobacco material in a different apparatus. Or, the alkaline solution may be applied to the residual tobacco material as it is transferred from a first extraction chamber where the first heating step has occurred to a second extraction chamber where a second heating step has occurred.

[0037] Preferably, the tobacco material is continuously circulated or agitated during the application of the alkaline solution, resulting in a uniform distribution of the alkaline solution. This optimizes the effect of the alkaline solution on the nicotine yield from the alkalized tobacco material.

[0038] Preferably, the pH of the alkalized tobacco material is at least about 8.5, more preferably at least about 9.0, and even more preferably at least about 9.5. Preferably, the pH of the alkalized tobacco material does not exceed 11.

[0039] "pH of alkalized tobacco material" refers to the pH of an aqueous suspension of alkalized tobacco material prepared by mixing alkalized tobacco material in water at a ratio of 1:20. The pH of the suspension was measured after a 30-minute soaking time.

[0040] As described above, in the alkaline treatment step, an alkaline solution is applied to the tobacco material or residual tobacco material. A suitable alkaline solution can be selected, for example, according to the desired pH of the tobacco material. Preferably, the alkaline solution is an aqueous solution of an alkali. A preferred example of a suitable alkaline solution for the alkaline treatment step is an aqueous solution of potassium carbonate. Other suitable alkaline solutions used in this invention include, but are not limited to, sodium hydroxide, sodium carbonate, and hydrogen peroxide.

[0041] Preferably, prior to the heating step, the water content of the alkalized tobacco material is between about 10% by weight and about 20% by weight, more preferably between about 12% by weight and about 20% by weight, and even more preferably between about 12% by weight and about 18% by weight. By providing alkalized tobacco material with a water content within this preferred range, it has been found that the extraction of volatile compounds during subsequent heating steps is optimized. Preferably, the desired water content of the alkalized tobacco material is provided by water in an alkaline solution, such that the application of water and alkali can be carried out in a single step. In this case, the concentration of the alkaline solution can be adjusted to provide the desired amount of water to the alkalized tobacco material. Alternatively, additional water can be added to the alkalized tobacco material separately from the alkaline solution.

[0042] In a method for alkaline treatment of residual tobacco material from a first heating step according to a second aspect of the invention, the residual tobacco material will typically have a low water content after heating during the first heating step. In such methods, it is particularly important to restore the water content of the residual tobacco material to a level between 10% and 20% by weight before the second heating step. As described above, this rewetting of the residual tobacco material is preferably achieved by including a sufficient amount of water in the alkaline solution applied to the residual tobacco material.

[0043] As defined above, in the method of the present invention, tobacco material is heated under specific heating conditions to release volatile tobacco components, which are collected to form a liquid tobacco extract. In an embodiment according to a first aspect of the invention, in which the tobacco material undergoes an alkaline treatment prior to the heating step, the tobacco material is alkalized by heating as described below.

[0044] During the heating step, the tobacco material is heated to an extraction temperature between approximately 100°C and approximately 160°C. It has been found that below this range, insufficient levels of nicotine and certain flavor compounds are released from the tobacco material, resulting in a liquid tobacco extract lacking the desired flavor characteristics. On the other hand, heating the tobacco material to temperatures above this defined range may release unacceptably high levels of certain undesirable tobacco compounds.

[0045] Preferably, the extraction temperature is at least about 110 degrees Celsius, more preferably at least about 115 degrees Celsius, more preferably at least about 120 degrees Celsius, and even more preferably at least about 125 degrees Celsius.

[0046] Preferably, the extraction temperature does not exceed about 150 degrees Celsius, more preferably not more than about 145 degrees Celsius, even more preferably not more than about 140 degrees Celsius, and most preferably not more than about 135 degrees Celsius.

[0047] For example, the extraction temperature can be between approximately 110°C and 150°C, or between approximately 120°C and 140°C, or between approximately 125°C and 135°C, or approximately 130°C. An extraction temperature of approximately 130°C has been found to provide a particularly optimized ratio of desired to undesired compounds in the liquid tobacco extract.

[0048] The tobacco material is heated at the extraction temperature for at least about 30 minutes, more preferably at least about 40 minutes, more preferably at least about 50 minutes, and even more preferably at least about 60 minutes. This extraction time is long enough to allow for the efficient extraction of desired tobacco flavor compounds, providing a liquid tobacco extract that produces an aerosol with the desired flavor characteristics. The inclusion of an alkaline treatment step allows for a relatively rapid heating step, wherein the heating duration is potentially shorter than that typically required in prior art extraction processes.

[0049] Preferably, the tobacco material is heated at the extraction temperature for no more than about 180 minutes, more preferably no more than about 120 minutes.

[0050] For example, tobacco material may be heated for about 30 minutes to about 180 minutes, or about 30 minutes to about 120 minutes, or about 40 minutes to about 180 minutes, or about 40 minutes to about 120 minutes, or about 50 minutes to about 180 minutes, or about 50 minutes to about 120 minutes, or about 60 minutes to about 180 minutes, or about 60 minutes to about 120 minutes.

[0051] The heating time indicated above corresponds to the duration of heating the tobacco material at the extraction temperature and does not include the time required to raise the temperature of the tobacco material to the extraction temperature.

[0052] In a method according to a first aspect of the invention, in which the tobacco material undergoes an alkaline treatment step prior to a first heating step, the amount of nicotine extracted from the alkalized tobacco material during the heating step preferably corresponds to at least about 10 grams per kg of dried tobacco material, more preferably at least about 12 grams per kg of dried tobacco material. As shown in the examples below, this nicotine extraction yield is significantly higher than that achievable using an equivalent extraction method but without an alkaline treatment step prior to heating.

[0053] The method of subjecting residual tobacco material to an alkaline treatment step according to a second aspect of the invention includes a second heating step to remove other volatile compounds, particularly nicotine, from the residual tobacco material.

[0054] In such methods, during the first heating step, the tobacco material is heated to an extraction temperature between about 100 degrees Celsius and about 160 degrees Celsius. Preferably, the extraction temperature of the first extraction step is at least about 110 degrees Celsius, more preferably at least about 115 degrees Celsius, more preferably at least about 120 degrees Celsius, and even more preferably at least about 125 degrees Celsius.

[0055] Preferably, the extraction temperature in the first extraction step does not exceed about 150 degrees Celsius, more preferably not more than about 145 degrees Celsius, even more preferably not more than about 140 degrees Celsius, and most preferably not more than about 135 degrees Celsius.

[0056] For example, the extraction temperature for the first extraction step can be between approximately 110°C and 150°C, or between approximately 120°C and 140°C, or between approximately 125°C and 135°C, or approximately 130°C. An extraction temperature of approximately 130°C has been found to provide a particularly optimized ratio of desired to undesired compounds in the liquid tobacco extract.

[0057] During the first heating step, the tobacco material is heated at the extraction temperature for at least about 90 minutes, more preferably at least about 120 minutes. Preferably, the tobacco starting material is heated at the extraction temperature for no more than about 270 minutes, more preferably no more than about 180 minutes. For example, the tobacco material may be heated for about 90 minutes to about 270 minutes, or about 90 minutes to about 180 minutes, or about 120 minutes to about 270 minutes, or about 120 minutes to about 180 minutes.

[0058] In the second heating step, the alkalized tobacco material is heated to an extraction temperature between approximately 100°C and approximately 160°C. The temperature of the second heating step may be the same as the temperature selected for the first heating step, or the temperature may be different.

[0059] Preferably, the extraction temperature of the second heating step is at least about 110 degrees Celsius, more preferably at least about 115 degrees Celsius, more preferably at least about 120 degrees Celsius, and even more preferably at least about 125 degrees Celsius.

[0060] Preferably, the extraction temperature in the second heating step does not exceed about 150 degrees Celsius, more preferably not more than about 145 degrees Celsius, even more preferably not more than about 140 degrees Celsius, and most preferably not more than about 135 degrees Celsius.

[0061] For example, the extraction temperature in the second heating step can be between about 110 degrees Celsius and 150 degrees Celsius, or between about 120 degrees Celsius and about 140 degrees Celsius, or between about 125 degrees Celsius and about 135 degrees Celsius, or about 130 degrees Celsius.

[0062] In such methods that include a second heating step, the alkalized tobacco material is preferably heated for at least 15 minutes, more preferably at least 20 minutes, more preferably at least 30 minutes, and even more preferably at least 40 minutes in the second heating step. The second heating step is generally shorter than the first heating step. Preferably, during the second heating step, the alkalized tobacco material is heated for no more than about 120 minutes, more preferably no more than about 90 minutes. For example, the alkalized tobacco material may be heated for about 15 minutes to about 120 minutes, or about 15 minutes to about 90 minutes, or about 20 minutes to about 120 minutes, or about 20 minutes to about 90 minutes, or about 30 minutes to about 120 minutes, or about 30 minutes to about 90 minutes, or about 40 minutes to about 120 minutes, or about 40 minutes to about 90 minutes.

[0063] Preferably, the extraction temperature and extraction time of the second heating step are selected to maximize the extraction of nicotine from the alkalized tobacco material.

[0064] The second heating step can be performed in the same extraction chamber as the first heating step or in a second extraction chamber. When the two extraction chambers are used for a separate heating step, the extraction chambers can be optionally connected to achieve a continuous flow of tobacco material through the extraction device.

[0065] In a method according to a second aspect of the invention, wherein an alkaline treatment step is performed on the residual tobacco material after a first heating step, the additional amount of nicotine extracted from the alkalized tobacco material during the second heating step corresponds to at least about 1 gram per kg of dried tobacco material, more preferably at least about 2 grams per kg of dried tobacco material. This nicotine yield is a supplement to the nicotine extracted from the tobacco material during the first heating step.

[0066] For each heating step, the extraction temperature and heating duration can be selected within the range defined above, depending on factors such as the type of tobacco, possible other components of the tobacco material, the desired nicotine level, or the desired composition of the liquid tobacco extract. By controlling the combination of extraction temperature and time, the composition of the liquid tobacco extract can be adjusted, specifically depending on the desired characteristics of the aerosol generated from the liquid tobacco extract. In particular, the proportion of specific tobacco compounds within the liquid tobacco extract can be adjusted to a certain extent by selecting extraction parameters to maximize the ratio of desired to undesired tobacco compounds within the liquid tobacco extract.

[0067] For any given tobacco material and for a specific tobacco compound, the variation in the release level of that compound with extraction temperature during the extraction process can be readily determined. For example, it has been found that the level of nicotine released from tobacco material generally increases with increasing extraction temperature. Different types of tobacco have been found to exhibit different rates of increase.

[0068] It has also been found that the levels of desired tobacco flavor compounds, such as β-damasne and β-ionone, released from tobacco material increase with increasing extraction temperature until a peak extraction temperature is reached, after which the levels begin to decrease. The peak extraction temperatures for these flavor compounds are typically in the range of 120°C to 160°C, allowing for effective optimization of the levels of desired flavor compounds in the extraction method of this invention.

[0069] It has been found that many undesirable tobacco compounds increase slowly as the extraction temperature rises to a threshold temperature, and a rapid increase is observed above this threshold temperature. This applies to levels of, for example, phenolic compounds, TSNA, and pyrazines, and in the case of flue-cured tobacco, to levels of furans and formaldehyde. In many cases, the threshold temperature is in the range of 120°C to 160°C, thus the levels of undesirable compounds can be effectively controlled in the extraction method of the present invention.

[0070] Preferably, the extraction temperature and extraction time are selected to provide a nicotine content of at least 0.1% by weight, more preferably at least about 0.2% by weight, in the liquid tobacco extract.

[0071] Preferably, in the method according to the second aspect of the invention, the extraction temperature or extraction time of the heating step or both extraction temperature and extraction time are selected to provide a weight ratio of at least about 0.25 of (β-ionone + β-damascenone) to (phenol) in the liquid tobacco extract.

[0072] β-Damalenone and β-ionone are desirable compounds associated with tobacco flavor. It has been found that the amount of β-damalenone and β-ionone released from tobacco material increases with increasing extraction temperature until a peak extraction temperature is reached, after which the levels begin to decrease. The peak extraction temperatures for these flavor compounds are typically in the range of 120°C to 160°C, allowing for efficient customization and control of the levels of desired flavor compounds in the extraction method.

[0073] Preferably, in the method according to the second aspect of the invention, the extraction temperature or extraction time of the heating step, or both the extraction temperature and extraction time, are selected to provide at least about 5 × 10⁻⁶ ppm in the liquid tobacco extract. -4 The weight ratio of (furanone + (2,3-diethyl-5-methylpyrazine)*100) to (nicotine).

[0074] It has been found that, in the method according to the invention, in which the extraction temperature is selected to provide a ratio within the aforementioned range, particularly good sensory properties can be obtained when the nicotine composition prepared from liquid tobacco extract is heated to generate an aerosol.

[0075] Suitable heating methods for heating tobacco materials will be those known to those skilled in the art and include, but are not limited to, dry distillation, water distillation, vacuum distillation, flash distillation, and thin-film water distillation.

[0076] One or more heating steps are preferably carried out in an inert atmosphere. Preferably, an inert gas stream, such as nitrogen, is passed through the tobacco material during the heating steps. In some cases, a combined stream of inert gas and water or steam may be used. Adding water or steam to the tobacco during extraction has been found to increase the yield of the extracted components. However, excessive addition of water or steam can lead to processing difficulties such as stickiness in the tobacco material.

[0077] Volatile tobacco compounds are released into an inert gas stream during the heating step, allowing the inert gas (or a combination of inert gas and water or steam) to act as a carrier for the volatile components. The inert gas flow rate can be optimized based on the size and geometry of the extraction chamber. A relatively high inert gas flow rate can advantageously improve the efficiency of extraction from tobacco material.

[0078] Generally, when tobacco materials are heated, any moisture present in the tobacco materials is also released as vapor along with volatile compounds.

[0079] An inert gas flow helps to remove the vapors and volatile compounds generated by the evaporation of the moisture contents of the tobacco material—especially nicotine or flavor-related compounds or both—from the extraction device.

[0080] Furthermore, using an inert gas stream, such as nitrogen, under slight overpressure in the extraction apparatus has the benefit of preventing the presence of oxygen within the extraction apparatus. This is desirable because it prevents any, even partial, combustion of the tobacco material during the heating step. Uncontrolled combustion of the tobacco material is obviously undesirable, as it represents a major safety risk within the manufacturing environment. However, the inventors have discovered that even limited partial combustion of the tobacco material can lead to a reduction in the quality of the tobacco extract obtainable by the method, which would also be undesirable.

[0081] Without being bound by theory, it should be understood that by preventing the combustion of tobacco material, the formation of any undesirable combustion byproducts is also prevented. Furthermore, since conditions conducive to the combustion of tobacco material are prevented, the conditions under which tobacco matrix (e.g., homogeneous tobacco material) is typically heated in "heat-not-burn" articles are simulated to some extent, effectively heating the tobacco material. As a result, it is advantageously preferable to selectively extract flavorful volatile species that lead consumers to associate them with heated tobacco.

[0082] Therefore, by performing the heating step in an inert atmosphere, extraction efficiency, product quality, and manufacturing safety will be advantageously enhanced.

[0083] Heating tobacco material in an inert gas stream has the added benefit that the inert gas stream containing volatile compounds can be more easily directed into a container containing an extraction solvent, such as a non-aqueous extraction liquid solvent.

[0084] Optionally, the heating step can be performed under a vacuum. This will remove any oxygen present in the extraction chamber, which advantageously prevents the tobacco material or volatile compounds generated during the heating of the tobacco material from reacting with oxygen. As described above, the removal of oxygen will also prevent any combustion of the tobacco material.

[0085] The method according to the invention may further include a step of spraying atomized water into the extraction chamber during the heating step. This has been found to improve heat exchange during the heating step, which is believed to be due to the vortices established within the extraction chamber by the evaporation of the atomized water. Due to the improved heat exchange, it has been found that including the step of spraying water into the extraction chamber during the heating step provides a further increase in nicotine yield, as well as an increase in the yield of certain desired flavor compounds from the tobacco material.

[0086] The spraying of atomized water can be generated and applied to the extraction chamber using any suitable method.

[0087] For example, the flow rate of atomized water sprayed into the extraction chamber can be adjusted according to the flow rate of the tobacco material in the extraction chamber. For example, the average flow rate of atomized water sprayed into the extraction chamber can be between about 3% and about 30% of the flow rate of the tobacco material.

[0088] Preferably, the atomized water is sprayed at a pressure of at least about 1 bar, more preferably at least about 2 bar, and even more preferably at least about 3 bar.

[0089] Methods of water atomization will be known to those skilled in the art. In some embodiments, water may be atomized in a compressed inert gas stream, such as air. In other embodiments, water may be atomized without airflow due to pressure within the nozzle.

[0090] Liquid tobacco extract can be produced from tobacco material composed of a single type of natural tobacco. Alternatively, the tobacco material may comprise a blend of two or more types of natural tobacco. The ratio of different tobacco types can be adjusted according to the desired characteristics of the aerosol generated from the liquid tobacco extract. For example, the proportion of Burley tobacco can be increased if a relatively high nicotine level is desired.

[0091] The term "natural tobacco," as used herein in this invention, describes any part of any plant member of the genus *Nicotiana*, including, but not limited to, leaves, midribs, stems, and petioles. In particular, natural tobacco may include fire-cured tobacco material, burley tobacco material, aromatic tobacco material, Maryland tobacco material, dark tobacco material, dark flue-cured tobacco material, yellow-flowered tobacco material, and material from other rare or specialty tobaccos, or blends thereof. As will be described in more detail below, tobacco material may be whole (e.g., whole leaves), shredded, cut, or ground.

[0092] In cases where it is desired to produce a liquid tobacco extract from a combination of two or more different tobacco types, the tobacco types may be heated separately at different extraction temperatures within a defined range of 100°C to 160°C, or the mixture of tobacco types may be heated together at a single extraction temperature within that range.

[0093] Tobacco materials can be solid tobacco materials, such as powder, leaf chips or fragments, or whole leaves. Alternatively, tobacco materials can be liquid tobacco materials, such as clumps, gels, slurries, or suspensions.

[0094] Tobacco materials may be derived from any suitable tobacco material, including but not limited to tobacco leaves, tobacco stems, reconstituted tobacco, cast tobacco, extruded tobacco, or tobacco-derived pellets.

[0095] Preferably, in the step of preparing the tobacco material, the tobacco is ground or cut to reduce the size of the tobacco particles in the tobacco material. This can advantageously improve the heating uniformity and extraction efficiency of the tobacco material.

[0096] The tobacco material may optionally be dried prior to the heating step to reduce its moisture content. Drying of the tobacco material can be carried out using any suitable chemical or physical drying process. Alternatively, water may be added to the tobacco material prior to the heating step to increase its moisture content.

[0097] In some embodiments of the invention, the step of preparing the tobacco material may include impregnating the tobacco material with an aerosol forming agent. When this impregnation of the tobacco material is performed prior to the heating step, it can advantageously increase the amount of certain desired tobacco compounds released from the tobacco material upon heating. For example, it has been found that impregnating the tobacco material with glycerol advantageously increases the amount of nicotine extracted from the tobacco material. In another example, it has been found that impregnating the tobacco material with a non-aqueous extraction solvent, such as propylene glycol, vegetable glycerol, 1,3-propanediol, triacetin, or mixtures thereof, which are also aerosol forming agents, advantageously increases the amount of flavor compounds extracted from the tobacco material.

[0098] In some embodiments, the tobacco material consists of natural tobacco that has not undergone any pretreatment steps, such as adjusting the water content. Thus, the water content in the tobacco material may be about 10 to 20% by weight (the water content typically present in natural tobacco material). In other embodiments, the tobacco material may include added water, as described above.

[0099] Alternatively or additionally, tobacco materials may include one or more additional components, such as non-aqueous solvents. An example of a suitable solvent is propylene glycol.

[0100] Therefore, the tobacco material may include at least about 40% by weight of natural tobacco material, or at least about 60% by weight of natural tobacco material, or at least about 80% by weight of natural tobacco material, or at least about 90% by weight of natural tobacco material, or at least about 95% by weight of natural tobacco material.

[0101] The water content in the tobacco starting material may be at least about 3% by weight. Preferably, the water content in the tobacco starting material is at least about 5% by weight. More preferably, the water content in the tobacco starting material is at least about 5% by weight. It should be understood that "water content in the tobacco starting material" may include water inherently present in natural tobacco material as well as any added water.

[0102] The water content in the tobacco starting material may be less than or equal to about 60% by weight. Preferably, the water content in the tobacco starting material is less than or equal to about 20% by weight. More preferably, the water content in the tobacco starting material is less than or equal to about 12% by weight.

[0103] In some embodiments, the water content in the tobacco starting material may be from about 3% to about 60% by weight, more preferably from about 3% to about 20% by weight, and even more preferably from about 3% to about 12% by weight. In other embodiments, the water content in the tobacco starting material may be from about 5% to about 60% by weight, more preferably from about 5% to about 20% by weight, and even more preferably from about 5% to about 12% by weight. In still other embodiments, the water content in the tobacco starting material may be from about 8% to about 60% by weight, more preferably from about 8% to about 20% by weight, and even more preferably from about 8% to about 12% by weight.

[0104] In some embodiments, the non-aqueous solvent content may be at least about 5% by weight, or at least about 10% by weight, or at least about 15% by weight, or at least about 20% by weight, or at least about 25% by weight, or at least about 30% by weight, or at least about 35% by weight, or at least about 40% by weight.

[0105] Optionally, the tobacco material may be enzymatically hydrolyzed prior to the heating step. This has been found to provide a significant increase in the yield of certain flavor compounds from the tobacco material.

[0106] Prior to the heating step, the tobacco material may be optionally analyzed to determine its composition, such as the reducing sugar content of alkaloids. This information about the composition can help in selecting an appropriate extraction temperature.

[0107] The method according to the invention may further include a step of microwave heating the tobacco material during at least one step of the method. The tobacco material may be microwave heated during a pretreatment step prior to the heating step. Alternatively or additionally, the tobacco material may be microwave heated during the main heating step, rather than conventional heating or in combination with conventional heating.

[0108] It has been found that incorporating a microwave heating step into the extraction method of the present invention provides a further increase in the extraction yield of nicotine.

[0109] During the heating of tobacco material, volatile compounds are released from the tobacco material in gaseous form. These volatile compounds are collected using any suitable technique. As described above, when the tobacco material is heated in an inert gas stream, the volatile compounds are collected from the inert gas stream. Different collection methods will be well known to those skilled in the art.

[0110] In some preferred embodiments, the step of collecting volatile compounds utilizes an absorption technique in which the volatile compounds are trapped in a non-aqueous extraction liquid solvent. For example, an inert gas stream containing the volatile compounds can be directed into a container of the non-aqueous extraction liquid solvent. The non-aqueous extraction liquid solvent is preferably an aerosol forming agent such as glyceryl triacetate, glycerol, 1,3-propanediol, propylene glycol, or combinations thereof. Using an aerosol forming agent as the liquid solvent is potentially advantageous because the aerosol forming agent can be retained as a diluent in the final liquid tobacco extract. This means that an additional step of removing the non-aqueous extraction solvent is unnecessary.

[0111] As used herein in conjunction with the invention, the term "aerosol forming agent" refers to a compound or mixture of compounds that will promote the formation of aerosols during use and is preferably substantially resistant to thermal degradation at the operating temperature of the aerosol-generating article or apparatus. Examples of suitable aerosol forming agents include: polyols such as propylene glycol, triethylene glycol, 1,3-propanediol, and glycerol; esters of polyols such as glycerol monoacetate, glycerol diacetate, or glycerol triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanoate and dimethyl tetradecanoate.

[0112] Preferably, the non-aqueous liquid solvent is maintained at a temperature below 0 degrees Celsius to optimize the transfer of volatile compounds into the liquid solvent. The non-aqueous extraction solvent is preferably maintained at a temperature not lower than -10 degrees Celsius. Temperatures below this value may lead to undesirable freezing phenomena.

[0113] In an alternative preferred embodiment, the step of collecting the volatile compounds can be performed using a condensation technique in which the volatile compounds are condensed and the condensate is collected. The condensation of the volatile compounds can be performed using any suitable equipment, such as in a refrigerated column. Preferably, the obtained condensate is added to a liquid aerosol forming agent, preferably propylene glycol.

[0114] Adding a liquid aerosol forming agent, particularly propylene glycol, during the collection step advantageously prevents condensed volatile compounds from splitting into two phases or forming emulsions, as is often the case with some tobacco components. Not wishing to be bound by theory, the inventors have observed that the solubility of tobacco components in the hydrolysate (i.e., the aqueous fraction of the naturally derived liquid tobacco extract) depends primarily on its polarity, its concentration, and the pH of the hydrolysate, which can vary depending on the type of tobacco. Consequently, if the amount of aerosol forming agent is insufficient, an oily layer tends to form on the surface of the naturally derived liquid tobacco extract. Such an oily material can accumulate at different locations on the collection and dehydration equipment in which the third and subsequent steps of the method are carried out. The addition of a liquid aerosol forming agent such as propylene glycol helps prevent the formation of such a layer and facilitates the homogenization of the naturally derived liquid tobacco extract. This, in turn, helps prevent any loss of desired flavor-related compounds during the fourth (dehydration) step, during which such compounds may undesirably deposit on the equipment surface.

[0115] In addition, liquid aerosol forming agents advantageously help capture flavor-related compounds, regardless of their polarity and volatility. Furthermore, during any subsequent drying step, liquid aerosol forming agents help prevent the loss of the most volatile fractions and facilitate the selective removal of excess water from naturally sourced liquid tobacco extracts to obtain concentrated tobacco extracts.

[0116] Using propylene glycol as an aerosol-forming agent in the collection step has a further advantage: propylene glycol exerts its antimicrobial activity by reducing the water activity of the aqueous solution. By adjusting the propylene glycol content in the liquid tobacco extract, it can also be ensured that the extract undergoes virtually no microbial activity.

[0117] As another alternative, the collection of volatile compounds can be carried out using adsorption techniques in which the volatile compounds are adsorbed onto the surface of a solid adsorbent material such as activated carbon. The adsorbed compounds are then transferred to a liquid solvent.

[0118] In the method of this invention, the next step is to form a liquid tobacco extract from the collected volatile compounds. The nature of this step may depend on the collection method. "Collected volatile compounds" generally includes a solution of tobacco-derived volatile compounds in a liquid solvent or carrier.

[0119] As described above, when volatile compounds are collected by absorption in a non-aqueous extraction solvent, the extraction method provides a liquid tobacco extract that may include more than about 25% by weight of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. In some embodiments, the liquid tobacco extract may include more than about 30% by weight of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract or more than about 35% by weight of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract.

[0120] The liquid tobacco extract may include less than or equal to about 65% by weight of a non-aqueous extraction solvent based on the liquid tobacco extract. In some embodiments, the liquid tobacco extract may include less than or equal to 60% or 55% by weight of a non-aqueous extraction solvent based on the liquid tobacco extract.

[0121] In some embodiments, the liquid tobacco extract may include from about 25% by weight to about 65% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. Alternatively, the liquid tobacco extract may include from about 25% by weight to about 60% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. Finally, the liquid tobacco extract may include from about 25% by weight to about 55% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract.

[0122] In other embodiments, the liquid tobacco extract may include from about 30% by weight to about 65% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may include from about 30% by weight to about 60% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may include from about 30% by weight to about 55% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract.

[0123] In further embodiments, the liquid tobacco extract may comprise from about 35% to about 65% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise from about 35% to about 60% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise from about 35% to about 55% by weight of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The non-aqueous extraction solvent is preferably triacetin, glycerol, propylene glycol, 1,3-propanediol, or mixtures thereof.

[0124] In a preferred embodiment, the weight ratio of (β-ionone + β-damascenone) to (phenol) in the liquid tobacco extract is at least about 0.25.

[0125] In a preferred embodiment, the weight ratio of (dimethylhydroxyfuranone + (2,3-diethyl-5-methylpyrazine)*100) to (nicotine) in the liquid tobacco extract is at least about 5 × 10⁻⁶. -4 .

[0126] When volatile compounds are collected by absorption in a liquid solvent, as described above, the step of forming a liquid tobacco extract preferably includes drying the solution of volatile compounds in the liquid solvent to concentrate the solution. This can be done, for example, to achieve a desired concentration of nicotine or flavor compounds. Drying can be carried out using any suitable method, including but not limited to dehydration, molecular sieving, freeze drying, phase separation, distillation, membrane permeation, controlled crystallization and filtration of water, reverse hygroscopic drying, ultracentrifugation, liquid chromatography, reverse osmosis, or chemical drying.

[0127] In a preferred embodiment, the solution of volatile compounds in a liquid solvent is concentrated by dehydration.

[0128] In other words, a solution of volatile compounds in a liquid solvent is heated to evaporate at least some of the water and obtain a concentrated tobacco extract. For this purpose, the solution of volatile compounds in a liquid solvent can be heated to a certain temperature for a certain time, causing the water content in the tobacco extract to decrease by at least approximately 60%.

[0129] The partially dehydrated concentrated tobacco extract can be considered a major product of the method according to the invention. The depleted tobacco material, from which volatile species and most of the moisture content have been extracted during heating in the second step, can be considered a byproduct of the method. Such depleted tobacco material typically has a moisture content of about 1 to 5% by weight, preferably about 2 to 3% by weight.

[0130] In one embodiment, the solution of the volatile compound in the liquid solvent is heated under vacuum, preferably at a temperature of at least about 70 degrees Celsius. In another embodiment, the solution of the volatile compound in the liquid solvent is heated under an air stream, preferably an air stream with relatively low humidity, at a temperature of at least about 35 degrees Celsius. Thus, a concentrated tobacco extract of natural origin can be obtained by the method according to the invention. One such concentrated tobacco extract of natural origin contains less than about 20% by weight of water.

[0131] Alternatively, in the case of collecting volatile compounds by condensation, the step of forming a liquid tobacco extract may include adding the condensate to a liquid solvent such as an aerosol forming agent.

[0132] Optionally, the steps for forming the liquid tobacco extract include a filtration step.

[0133] Optionally, the steps of forming the liquid tobacco extract include a blending step, in which extracts derived from different tobacco materials are combined.

[0134] Optionally, the steps of forming a liquid tobacco extract include adding one or more additives, such as organic acids, to a solution of volatile compounds. However, in many cases, liquid tobacco extracts are suitable for use without the presence of additives.

[0135] In an embodiment of the second aspect of the invention, in which the residual tobacco material from the first heating step is subjected to an alkalization treatment step, two separate liquid tobacco extracts are produced during the extraction method: a first liquid tobacco extract from the first heating step of the tobacco material and a second liquid tobacco extract from the second heating step of the alkalized tobacco material. Preferably, such a method further includes the step of combining the first liquid tobacco extract and the second liquid tobacco extract.

[0136] In some embodiments, nicotine from the second liquid tobacco extract can be isolated, and at least a portion of the isolated nicotine can be added to the first liquid tobacco extract. This produces a liquid tobacco extract with enhanced nicotine levels without affecting the flavor characteristics of the first liquid tobacco extract.

[0137] The present invention further provides a liquid tobacco extract produced by a method according to the invention as described in detail above. As stated above, the method of the present invention advantageously produces a natural liquid tobacco extract having a highly desirable ratio of desired tobacco compounds such as nicotine and flavor compounds to undesired tobacco compounds.

[0138] The liquid tobacco extract is particularly suitable for producing nicotine compositions, such as liquid nicotine compositions or gel nicotine compositions, for use in aerosol generation systems. In such aerosol generation systems, the nicotine composition is typically heated within the aerosol generation apparatus.

[0139] As used herein, the term "aerosol generating apparatus" refers to an apparatus comprising a heater element that interacts with a nicotine composition incorporating a liquid tobacco extract, such as a liquid tobacco extract obtained by the method according to the invention, to generate an aerosol. During use, volatile compounds are released from the nicotine composition via heat transfer and entrained in the air drawn through the aerosol generating apparatus. When the released compounds cool, they condense to form an aerosol inhaled by the consumer.

[0140] When a nicotine composition comprising a liquid tobacco extract according to the invention is heated, an aerosol containing volatile compounds collected from the tobacco material during the extraction process is released. The composition and characteristics of the resulting aerosol produced from the liquid tobacco extract and delivered to the consumer can be adjusted by controlling the parameters of the extraction parameters to control the composition of the liquid tobacco extract.

[0141] The nicotine composition can be a liquid tobacco extract produced by the extraction process according to the present invention without the addition of more nicotine. The nicotine composition can be a liquid tobacco extract produced by the extraction process according to the present invention without the addition of more flavor compounds. The nicotine composition can be a liquid tobacco extract produced by the extraction process according to the present invention without the addition of more dimethyl hydroxyfuranone. The nicotine composition can be a liquid tobacco extract produced by the extraction process according to the present invention without the addition of more solvent.

[0142] Alternatively, liquid tobacco extracts can undergo additional processing steps to form a nicotine composition. Even when subjected to such additional steps, a nicotine composition can be formed without the need to add more nicotine or flavor compounds.

[0143] Preferably, the liquid tobacco extract can be concentrated in a dehydration step as described above to form a concentrated tobacco extract, and the concentrated tobacco extract can be used to form a nicotine composition.

[0144] Preferably, the concentrated tobacco extract comprises 8% to 15% by weight of water based on the weight of the concentrated tobacco extract.

[0145] The dehydration step provides a concentrated tobacco extract, which may have a non-aqueous extraction solvent content of about 65% to about 95% by weight, preferably about 65% to 85% by weight, and most preferably about 75% to about 85% by weight. The non-aqueous extraction solvent is preferably triacetylglycerol, glycerol, propylene glycol, 1,3-propanediol, or mixtures thereof.

[0146] The dehydration step provides a concentrated tobacco extract, which may have a nicotine content of at least about 0.2% by weight, preferably about 0.5% by weight to about 12% by weight, and most preferably about 2% by weight to about 8% by weight.

[0147] Preferably, an additional non-aqueous solvent may be added to the liquid tobacco extract or concentrated tobacco extract to form a nicotine composition.

[0148] The nicotine composition may be a liquid nicotine composition or a gel nicotine composition.

[0149] The nicotine composition may include at least about 10% by weight of liquid tobacco extract. Preferably, the nicotine composition includes at least about 20% by weight of liquid tobacco extract. More preferably, the nicotine composition includes at least about 30% by weight of liquid tobacco extract. In preferred embodiments, the nicotine composition includes at least about 40% by weight of liquid tobacco extract, more preferably at least about 50% by weight of liquid tobacco extract, and even more preferably at least about 60% by weight of liquid tobacco extract. In particularly preferred embodiments, the nicotine composition includes at least about 65% by weight of liquid tobacco extract, more preferably at least about 70% by weight of liquid tobacco extract, even more preferably at least about 75% by weight of liquid tobacco extract, and most preferably at least about 80% by weight of liquid tobacco extract.

[0150] In some embodiments, the liquid tobacco extract is a concentrated tobacco extract. The nicotine composition may include at least about 10% by weight of concentrated tobacco extract, at least about 20% by weight of concentrated tobacco extract, at least about 30% by weight of concentrated tobacco extract, at least about 40% by weight of concentrated tobacco extract, at least about 50% by weight of concentrated tobacco extract, preferably at least about 60% by weight of concentrated tobacco extract, more preferably at least about 70% by weight of concentrated tobacco extract, even more preferably at least about 75% by weight of concentrated tobacco extract, and most preferably at least about 80% by weight of concentrated tobacco extract.

[0151] In some embodiments, the nicotine composition comprises about 40% to about 95% by weight of liquid tobacco extract. More preferably, the nicotine composition comprises about 40% to about 95% by weight of liquid tobacco extract. Even more preferably, the nicotine composition comprises about 50% to about 95% by weight of liquid tobacco extract. Most preferably, the nicotine composition comprises about 60% to about 95% by weight of liquid tobacco extract. In some particularly preferred embodiments, the nicotine composition comprises about 70% to about 95% by weight of liquid tobacco extract, and even more preferably about 80% to about 95% by weight of liquid tobacco extract.

[0152] In some embodiments, the nicotine composition comprises about 40% to about 90% by weight of liquid tobacco extract. More preferably, the nicotine composition comprises about 40% to about 90% by weight of liquid tobacco extract. Even more preferably, the nicotine composition comprises about 50% to about 90% by weight of liquid tobacco extract. Most preferably, the nicotine composition comprises about 60% to about 90% by weight of liquid tobacco extract. In some particularly preferred embodiments, the nicotine composition comprises about 70% to about 90% by weight of liquid tobacco extract, and even more preferably about 80% to about 90% by weight of liquid tobacco extract.

[0153] In some embodiments, the nicotine composition comprises about 40% to about 85% by weight of liquid tobacco extract. More preferably, the nicotine composition comprises about 40% to about 85% by weight of liquid tobacco extract. Even more preferably, the nicotine composition comprises about 85% to about 90% by weight of liquid tobacco extract. Most preferably, the nicotine composition comprises about 60% to about 85% by weight of liquid tobacco extract. In some particularly preferred embodiments, the nicotine composition comprises about 70% to about 85% by weight of liquid tobacco extract, even more preferably about 80% to about 85% by weight of liquid tobacco extract.

[0154] The nicotine composition may include up to about 100% by weight of liquid tobacco extract. In some embodiments, the nicotine composition may be formed directly from the liquid tobacco extract without the addition of additional non-aqueous solvents, flavorings, or nicotine. That is, the nicotine composition may include 100% by weight of liquid tobacco extract. In some embodiments, the liquid tobacco extract is a concentrated tobacco extract, such that the nicotine composition may include 100% by weight of concentrated tobacco extract. In embodiments where the nicotine composition includes 100% by weight of liquid tobacco extract or 100% by weight of concentrated tobacco extract, no additional non-aqueous solvent is present.

[0155] Alternatively, in some embodiments, the nicotine composition comprising the liquid tobacco extract may include an additional non-aqueous solvent. This additional non-aqueous solvent is one that has been added after the extraction step. It is also a solvent that supplements the non-aqueous extraction solvent present in the liquid tobacco extract. In embodiments where the liquid tobacco extract is a concentrated tobacco extract, the nicotine composition comprising the concentrated tobacco extract may include an additional non-aqueous solvent.

[0156] The additional non-aqueous solvent may be an aerosol forming agent. Preferably, the additional non-aqueous solvent is glyceryl triacetate, glycerol, propylene glycol, 1,3-propanediol, or a mixture thereof.

[0157] In embodiments where the nicotine composition includes an additional non-aqueous solvent, the nicotine composition may include 90% by weight or less of the additional non-aqueous solvent. Preferably, the nicotine composition includes 80% by weight or less of the additional non-aqueous solvent. More preferably, the nicotine composition includes 70% by weight or less of the additional non-aqueous solvent. In preferred embodiments, the nicotine composition includes about 60% by weight or less of the additional non-aqueous solvent, more preferably about 50% by weight or less of the additional non-aqueous solvent, and even more preferably about 40% by weight or less of the additional non-aqueous solvent. In particularly preferred embodiments, the nicotine composition includes about 35% by weight or less of the additional non-aqueous solvent, more preferably about 30% by weight or less of the additional non-aqueous solvent, even more preferably about 25% by weight or less of the additional non-aqueous solvent, and most preferably about 20% by weight or less of liquid tobacco extract.

[0158] In the nicotine composition prepared by the method according to the invention, at least 50% by weight of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80% by weight of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. Even more preferably, at least 90% by weight of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction.

[0159] In the nicotine composition prepared by the method according to the invention, at least 50% by weight of the non-aqueous extraction solvent content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80% by weight of the non-aqueous extraction solvent content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. Even more preferably, at least 90% by weight of the non-aqueous extraction solvent content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction.

[0160] In the nicotine composition prepared by the method according to the invention, at least 50% by weight of the water content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80% by weight of the water content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction. Even more preferably, at least 90% by weight of the water content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from tobacco extract rather than being added after extraction.

[0161] In the nicotine composition prepared by the method according to the invention, at least 50% by weight of the desired tobacco flavor species content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from a tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80% by weight of the desired tobacco flavor species content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from a tobacco extract rather than being added after extraction. Even more preferably, at least 90% by weight of the desired tobacco flavor species content in the nicotine composition, based on the total weight of the nicotine composition, may be derived from a tobacco extract rather than being added after extraction.

[0162] The total content of non-aqueous solvents in the nicotine composition includes the non-aqueous extraction solvent and the aforementioned additional non-aqueous solvents, if present. The nicotine composition may comprise from about 10% by weight to about 95% by weight of total non-aqueous solvents. The nicotine composition preferably comprises from about 50% to about 95% by weight, for example from about 65% to about 95% by weight, more preferably from about 70% to about 90% by weight, and most preferably from about 80% to about 90% by weight of non-aqueous solvents. The non-aqueous solvents are preferably triacetin, glycerin, propylene glycol, 1,3-propanediol, or mixtures thereof.

[0163] The nicotine composition may include propylene glycol in a total content of about 10% to about 95% by weight. The nicotine composition may include about 20% to about 95% by weight, such as about 50% to about 95% by weight, or about 65% to about 95% by weight, about 70% to about 90% by weight, or about 80% to about 90% by weight of propylene glycol in a total content of about 20% to about 95% by weight, or ....

[0164] The nicotine composition may include a total content of about 10% by weight to about 95% by weight of triglycerides. The nicotine composition may include a total content of about 20% by weight to about 95% by weight, such as about 50% by weight to about 95% by weight, about 70% by weight to about 90% by weight, or about 65% by weight to about 95% by weight, or about 80% by weight to about 90% by weight of triglycerides.

[0165] The nicotine composition may include a total glycerol content of about 10% by weight to about 95% by weight. The nicotine composition may include a total glycerol content of about 20% by weight to about 95% by weight, such as about 50% by weight to about 95% by weight, or about 65% by weight to about 95% by weight, about 70% by weight to about 90% by weight, or about 80% by weight to about 90% by weight.

[0166] The nicotine composition may include a total content of about 10% by weight to about 95% by weight of 1,3-propanediol. The nicotine composition may include a total content of about 20% by weight to about 95% by weight, such as about 50% by weight to about 95% by weight, or about 65% by weight to about 95% by weight, or about 80% by weight to about 90% by weight of 1,3-propanediol.

[0167] The nicotine composition of the present invention comprises at least 0.2% by weight of nicotine. More preferably, the nicotine content in the liquid tobacco extract of the nicotine composition is at least about 0.4% by weight. The nicotine composition may have a nicotine content of about 12% by weight or less, for example about 10% by weight or less, preferably about 8% by weight or less, more preferably about 5% by weight or less, and preferably about 3.6% by weight or less. Most preferably, the nicotine composition comprises between about 0.4% by weight and 3.6% by weight of nicotine based on the weight of the nicotine composition.

[0168] The nicotine composition may comprise between 1 wt% and 85 wt% water. The nicotine composition may comprise between 2 wt% and 50 wt% water. The nicotine composition may comprise between 3 wt% and 30 wt% water. The nicotine composition may comprise between 5 wt% and 25 wt% water. The nicotine composition may comprise between 8 wt% and 20 wt% water. The nicotine composition preferably comprises between 10 wt% and 15 wt% water.

[0169] In some embodiments, the nicotine composition may include one or more water-soluble organic acids. As used herein in conjunction with the invention, the term "water-soluble organic acid" describes an organic acid with a water solubility greater than or equal to about 500 mg / ml at 20°C.

[0170] The one or more water-soluble organic acids can advantageously bind to nicotine in the liquid tobacco extract by forming one or more nicotine salts. The one or more nicotine salts are advantageously soluble and stable in water or non-aqueous solvents present in the liquid tobacco extract. As described above, this can advantageously reduce nicotine adsorption in the upper airways and enhance nicotine delivery and retention in the lungs.

[0171] Preferably, the nicotine composition has a water-soluble organic acid content of greater than or equal to about 2% by weight. More preferably, the nicotine composition has a water-soluble organic acid content of greater than or equal to about 3% by weight.

[0172] Water-soluble organic acids can include acetic acid.

[0173] Exogenous acetic acid is acetic acid added from a source other than tobacco plant material, and is not acetic acid naturally present in tobacco plants that has been isolated, removed, or derived from tobacco plant material using extraction treatment conditions and techniques.

[0174] If acetic acid is added to a liquid tobacco extract to form a nicotine composition, the total acetic acid content in the nicotine composition, including exogenous and endogenous acetic acid, is preferably from about 0.01% by weight to about 8% by weight, for example, between about 0.03% by weight to about 8% by weight, about 0.3% by weight to about 8% by weight, about 2% by weight to about 8% by weight, or about 3% by weight to about 8% by weight. More preferably, the total acetic acid content is from about 0.01% by weight to about 6% by weight, for example, between about 0.03% by weight to about 6% by weight, about 0.3% by weight to about 6% by weight, about 2% by weight to about 6% by weight, or about 3% by weight to about 6% by weight.

[0175] Preferably, the nicotine composition has a water-soluble organic acid content of less than or equal to about 8% by weight. More preferably, the nicotine composition has a water-soluble organic acid content of less than or equal to about 6% by weight.

[0176] Preferably, the nicotine composition has a water-soluble organic acid content between about 2% by weight and about 8% by weight. For example, the nicotine composition may have a water-soluble organic acid content between about 2% by weight and about 6% by weight.

[0177] More preferably, the nicotine composition has a water-soluble organic acid content between about 3% by weight and about 8% by weight. For example, the nicotine composition may have a water-soluble organic acid content between about 3% by weight and about 6% by weight.

[0178] Nicotine compositions may include one or more non-tobacco-derived edible flavorings. Suitable non-tobacco-derived edible flavorings include, but are not limited to, menthol.

[0179] Preferably, the nicotine composition has a content of less than or equal to about 4% by weight of non-tobacco-derived edible flavorings. More preferably, the nicotine composition has a content of less than or equal to about 3% by weight of non-tobacco-derived flavorings. For example, the liquid tobacco extract produced by the method of the present invention can be used to prepare a nicotine composition comprising 10 to 20 mg of nicotine per milliliter without the need for added nicotine.

[0180] Suitable nicotine compositions for use in aerosol generation systems may comprise a combination of liquid tobacco extract produced in the method according to the invention with water and additional aerosol forming agents. The nicotine composition may comprise, for example, water in the range of about 10% to about 20% by weight.

[0181] Nicotine compositions comprising a liquid tobacco extract according to the invention can be provided in a cartridge for use in an aerosol generation system. The cartridge may include an atomizer configured to generate an aerosol from the nicotine composition. The atomizer may be a thermal atomizer configured to heat the nicotine composition to generate an aerosol. The thermal atomizer may include, for example, a heater and a liquid delivery element configured to deliver the nicotine composition to the heater. The liquid delivery element may include a capillary wick. Alternatively, the atomizer may be a non-thermal atomizer configured to generate an aerosol from the nicotine composition in a non-thermal manner. Non-thermal atomizers may be, for example, impingement jet atomizers, ultrasonic atomizers, or vibrating mesh atomizers.

[0182] The cartridge containing a nicotine composition formed from the liquid tobacco extract of the present invention can be used in conjunction with any suitable aerosol generating device, which includes a housing configured to receive at least a portion of the cartridge. The aerosol generating device may include a battery and control electronics.

[0183] Embodiments of the present invention will now be further described by way of example only.

[0184] Comparative Example

[0185] In the method according to a first aspect of the invention, tobacco material is cut to form tobacco fragments with a maximum size of 2.5 mm by 2.5 mm, and the tobacco fragments are loaded into an extraction chamber without compression. The tobacco material is sprayed with an aqueous potassium carbonate solution to provide alkalized tobacco material with a pH of 9.5. The alkalized tobacco material is heated to a temperature of 140 degrees Celsius in the extraction chamber for a period of 120 minutes. During heating, a nitrogen gas stream passes through the extraction chamber at a flow rate of approximately 20 liters per minute. The tobacco flow rate is 30 kg per hour, and the extraction chamber rotates at a speed of 1 rpm to circulate the tobacco.

[0186] Volatile compounds released from the tobacco material during the heating step are collected by condensation at 0 degrees and added to a liquid solvent of propylene glycol.

[0187] The nicotine composition 1 shown in the table below is a liquid tobacco extract obtained directly from an extraction process according to a first aspect of the invention, wherein the alkaline treatment step is carried out before heating.

[0188] In the second comparative extraction method, tobacco material is extracted under the same conditions as described above, except that the alkaline treatment step is omitted. Therefore, the second extraction method is not based on the present invention. The nicotine composition 2 shown in the table below is a liquid tobacco extract obtained directly from this second extraction method.

[0189] Each nicotine composition was analyzed to measure nicotine content, and nicotine yield was calculated based on the total dry weight of the tobacco material. Extraction yields of certain flavor compounds were also measured. The results of this analysis are shown in the table below:

[0190] Nicotine Composition 1 Nicotine Composition 2 Nicotine extraction yield (g / kg dry tobacco) 13.3 1.6 2,3-Diethyl-5-methylpyrazine extraction yield (μg / kg dry tobacco) 10.5 1.3 Yield of 2-ethyl-3,5-dimethylpyrazine (μg / kg dry tobacco) 153 12

[0191] As clearly shown in the table above, including the alkaline treatment step in the method according to the first aspect of the invention provides a significant increase in nicotine extraction yield compared to methods that omit the alkaline treatment step. Also as shown in the table above, the inclusion of the alkaline treatment step provides a significantly increased extraction yield for certain pyrazine flavor compounds, including 2-ethyl-3,5-dimethylpyrazine and 2,3-diethyl-5-methylpyrazine.

Claims

1. A method for producing a liquid tobacco extract, the method comprising the following steps: Preparation of tobacco materials; The tobacco material is first heated for at least 90 minutes at an extraction temperature between 100°C and 160°C. Collect volatile compounds released from the tobacco material during the first heating step; A first liquid tobacco extract comprising the collected volatile compounds from the tobacco material is formed; An alkaline solution is applied to the residual tobacco material from the first heating step to produce alkalized tobacco material; The alkalized tobacco material is heated a second time at an extraction temperature between 100 degrees Celsius and 160 degrees Celsius. Collect volatile compounds released from the alkalized tobacco material during the second heating step; as well as A second liquid tobacco extract is formed, comprising the collected volatile compounds from the alkalized tobacco material.

2. The method of claim 1, further comprising the step of combining the first liquid tobacco extract and the second liquid tobacco extract.

3. The method of claim 1, further comprising the following steps: The process of separating nicotine from the second liquid tobacco extract and combining at least a portion of the nicotine separated from the second liquid tobacco extract with the first liquid tobacco extract.

4. The method according to claim 1, 2 or 3, wherein heating is performed in an inert gas stream during at least one of the first heating step and the second heating step.

5. The method according to claim 1, 2 or 3, wherein the pH of the alkalized tobacco material is at least 8.

5.

6. The method according to claim 1, 2 or 3, wherein the pH of the alkalized tobacco material is at least 9.

0.

7. The method according to claim 1, 2 or 3, wherein the alkaline solution is sprayed onto the residual tobacco material, and wherein the residual tobacco material is continuously agitated during the spraying.

8. The method according to claim 1, 2 or 3, wherein the alkaline solution is an aqueous solution of potassium carbonate.

9. The method according to claim 1, 2 or 3, wherein the water content of the alkalized tobacco material is between 10% by weight and 20% by weight before the second heating step.

10. The method of claim 1, wherein the amount of nicotine extracted from the alkalized tobacco material during the second heating step corresponds to at least 1 gram per kg of dried tobacco material.

11. The method according to claim 1, 2 or 3, wherein the tobacco material is first heated at an extraction temperature between 135 degrees Celsius and 150 degrees Celsius.

12. The method according to claim 1, 2 or 3, wherein the alkalized tobacco material is secondly heated at an extraction temperature between 135 degrees Celsius and 150 degrees Celsius.

13. The method according to claim 1, 2 or 3, further comprising the step of spraying atomized water into the extraction chamber during the first heating step and / or the second heating step.

14. The method according to claim 1, 2 or 3, further comprising the step of drying the collected volatile compounds during the first heating step and / or the second heating step.

15. The method according to claim 1, 2 or 3, further comprising the step of concentrating the collected volatile compounds during the first heating step and / or the second heating step.