Improved method for producing liquid tobacco extract

Abstract

A method for making a liquid tobacco extract, the method comprising the steps of preparing a tobacco starting material; adding an alkaline solution to the tobacco starting material to form an alkalized tobacco material; heating the alkalized tobacco material in an extraction chamber at an extraction temperature of 100 degrees Celsius to 160 degrees Celsius for at least 30 minutes, wherein the alkalized tobacco material is heated in a flow of inert gas or a combination of inert gas and water or steam, and wherein the moisture content of the alkalized tobacco material is between 10 percent and 20 percent by weight prior to the heating step; condensing volatile compounds released from the tobacco starting material during the heating step and collecting the condensed volatile compounds; and forming a liquid tobacco extract comprising the condensed volatile compounds.

Description

【Technical Field】 【0001】 The present invention relates to a method for producing a liquid tobacco extract and a liquid tobacco extract produced by such a method. 【Background Art】 【0002】 An aerosol generation system for delivering an aerosol to a user, comprising an atomizer configured to generate an inhalable aerosol from a liquid formulation such as a liquid nicotine formulation, is known. Some known aerosol generation systems include a thermal atomizer, such as an electric heater, configured to heat and vaporize the liquid formulation to generate an aerosol. One popular type of electrically heated aerosol generation system is an e-cigarette. Other known aerosol generation systems include non-thermal atomizers configured to generate an aerosol from a liquid formulation using, for example, impinging jets, ultrasonic, or vibrating mesh technology. 【0003】 Several methods for generating a liquid tobacco extract from tobacco material are known. The liquid tobacco extract can be produced by a high-temperature extraction process in which nicotine and other volatile flavor compounds are extracted from the tobacco material and collected in a suitable solvent to form a natural liquid tobacco extract. 【0004】 A maceration method is also known in which the tobacco material is held in suspension in the extractant for a period of up to several weeks or months. The resulting slurry is then filtered and the liquid phase thus collected can be used to produce a vaporizable liquid formulation. In one such method, the so-called "cold maceration method", there is generally no way to control the extraction conditions (e.g., temperature and pressure). For example, in a variant of the maceration method described in US Patent No. 2012 / 192880, the slurry is heated to 100 degrees Celsius or more. 【0005】 The liquid phase collected during slurry filtration corresponds to the primary product of the maceration process and tends to be highly diluted with a low content of nonpolar tobacco flavor varieties. Furthermore, the liquid phase usually contains little to no nicotine. Therefore, liquid extracts obtained by maceration generally need to be supplemented with additional components such as nicotine salts and glycerin before being used in vaporizable liquid formulations. 【0006】 An alternative process is known in which tobacco material is substantially boiled in water for several hours or days to form a vapor phase, and the distillate obtained by the 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】 Meanwhile, a waxy layer accumulates, and the aqueous portion containing nicotine and other water-soluble compounds is recycled to the boiler. To increase the extraction yield, a nonpolar cosolvent may be optionally supplied to the boiler along with the aqueous portion. Meanwhile, the waxy phase is collected, ultimately forming one of the primary products of such a steam distillation process. These products are often referred to as "tobacco essential oil" and have a high proportion of nonpolar compounds present in tobacco, such as fatty acids and neophytadienes. Tobacco essential oil obtained by one such method typically does not contain nicotine. 【0008】 Furthermore, tobacco materials are known to be subjected to extraction processes using volatile, nonpolar solvents. Examples of suitable solvents include cyclic or acyclic short alkanes and chlorinated solvents such as dichloromethane. In one such process, excess solvent can be evaporated by controlled heating under vacuum. Typically, this is done in the presence of ethanol, which has a higher boiling point than the extraction solvent, so that even trace amounts of the extraction solvent can be detected. 【0009】 One primary product of such solvent-assisted extraction processes is often called "tobacco absolute" and may contain trace amounts of ethanol. This is a waxy product containing a high concentration mixture of most nonpolar compounds that can be extracted with a particular solvent, and generally contains nicotine, which is present in relatively high concentrations. 【0010】 Alternative extraction processes involve contacting tobacco material with a solvent under supercritical conditions, such as supercritical carbon dioxide. One such process, disclosed in U.S. Patent No. 2013 / 160777, relies on the principle that volatile substances in the feed material can be separated into a supercritical phase upon contact with a supercritical fluid. After dissolving any soluble material, the supercritical fluid containing the dissolved substance can be removed, separating the dissolved components of the feed material from the supercritical fluid. The primary product of a supercritical extraction process is substantially similar to a "tobacco absolute" from a solvent-assisted extraction process performed at lower temperatures and pressures, contains no residual solvent, typically has high levels of waxy, nonpolar compounds, and generally contains nicotine, which is present in relatively high concentrations. 【0011】 However, all tobacco extracts 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 furaneol. 【0012】 Generally, as discussed above, liquid tobacco extracts obtained by these known extraction processes may contain low levels of nicotine. Furthermore, liquid tobacco extracts obtained by these extraction processes may have low levels and a limited variety of flavors. Liquid tobacco extracts obtained by these extraction processes may also have high levels of undesirable compounds. Generally, the concentrations of nicotine, flavors, and undesirable compounds obtained by these extraction processes can be significantly influenced by the type or combination of tobaccos used as starting materials. 【0013】 The object of the present invention is to mitigate one or more drawbacks of liquid tobacco extracts obtained by known processes. In particular, it would be desirable to provide a method for producing novel and improved liquid tobacco extracts. It would be especially desirable to provide a method for producing liquid tobacco extracts that can be carried out more efficiently than existing processes. [Overview of the project] 【0014】 This disclosure relates to a method for preparing a liquid tobacco extract from tobacco material. The method may include a step of preparing tobacco material. An alkaline solution may be applied to the tobacco material to prepare alkalized tobacco material. The alkalized tobacco material may be heated to an extraction temperature of about 100°C to about 160°C. The heating may be carried out for at least 30 minutes. The alkalized tobacco material may be heated in a flow of inert gas or in a flow of a combination of inert gas and water or vapor. The method may further include a step of condensing volatile compounds released from the alkalized tobacco material during the heating step, and a step of collecting the condensation of volatile compounds. The method may further include a step of forming a liquid tobacco extract containing the condensation of 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 tobacco material. The tobacco material may be heated for at least 90 minutes at an extraction temperature of 100°C to 160°C. The method may further include a step of collecting volatile compounds released from the tobacco starting material during the heating step, and a step of forming a first liquid tobacco extract containing the volatile compounds from the collected tobacco starting material. The method may further include a step of adding 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 of 100°C to 160°C. The method may further include a step of collecting volatile compounds released from the alkalized tobacco material during the heating step, and a step of forming a second liquid tobacco extract containing the volatile compounds from the collected 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; adding an alkaline solution to a tobacco starting material to produce an alkalized tobacco material; heating the alkalized tobacco material at an extraction temperature of about 100 degrees Celsius to about 160 degrees Celsius for at least about 30 minutes, wherein the alkalized tobacco material is heated in a flow of inert gas or in a flow of a combination of inert gas and water or vapor; condensing volatile compounds released from the alkalized tobacco material during the heating step and collecting the condensates of volatile compounds; and forming a liquid tobacco extract containing the condensates of volatile compounds. 【0017】 A second aspect of the present invention provides a method for producing a liquid tobacco extract, 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 containing the collected volatile compounds derived from the tobacco starting material; adding 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 of 100°C to 160°C; collecting volatile compounds released from the alkalized tobacco material during the heating step; and forming a second liquid tobacco extract containing the recovered volatile compounds derived from the alkalized tobacco material. 【0018】 According to the present invention, a liquid tobacco extract prepared by the method of the present invention as defined above is further provided. 【0019】 As used herein in connection with the present invention, the term “liquid tobacco extract” refers to the direct product of an extraction process performed on tobacco material. Therefore, tobacco extracts typically contain a mixture of natural components separated from, removed from, or derived from natural tobacco material using tobacco extraction processing conditions and techniques. Thus, in one such process, extracted tobacco components are removed from natural tobacco material and separated from unextracted tobacco components. According to the present invention, an extraction process for producing a liquid tobacco extract involves heating tobacco material under specific heating conditions and collecting the resulting volatile compounds. Thus, a liquid tobacco extract consists of a mixture of natural tobacco components derived from tobacco material and extracted or formed during the extraction process, typically combined with one or more materials other than tobacco material, such as a non-aqueous extraction solvent used during the extraction process. As will be described in more detail below, volatile compounds released from the starting tobacco material can be collected using absorption techniques in which the volatile compounds are trapped in the non-aqueous extraction solvent. As an example, an inert gas stream containing the volatile compounds may be directed into a container of the non-aqueous extraction solvent. The non-aqueous extraction solvent is preferably an aerosol-forming agent. 【0020】 The present invention provides a novel extraction method comprising an alkali treatment step in which an alkaline solution is added to tobacco material. According to a first aspect of the present invention, the alkali treatment step may be performed on the tobacco material before the heating step. It has been found that including the alkali treatment step before heating, in combination with conditions defined for heating, results in a significant increase in nicotine yield. For example, it has been confirmed that performing the alkali treatment step increases the nicotine extraction yield by up to 900% compared to cases without the alkali treatment step. It has also been found that including the alkali treatment step before heating results in a favorable change in the balance of flavor compounds in the resulting extract. In particular, the yield of certain desirable flavor compounds, such as certain pyrazine compounds, can be improved. Advantageously, the increase in the yield of nicotine and other flavor compounds is achieved without increasing the yield of TSNA. Overall, the ratio of desirable to undesirable compounds in the extract can be increased. 【0021】 While not intended to be constrained by theory, it is thought that alkali treatment of tobacco materials facilitates the transfer of nicotine from its protonated form to its free base form, thereby helping to more efficiently transfer nicotine into the gas phase during the heating process. 【0022】 In an alternative method according to a second aspect of the present invention, the alkali treatment step is performed on the residual tobacco material remaining after the heating step. The alkalized tobacco material is then subjected to a second heating step to extract further volatile compounds, which may optionally be added to the volatile compounds recovered from the first heating step. Thus, such a method involves two separate heating steps performed on the same batch or sample of tobacco material. 【0023】 "Residual tobacco material" refers to the tobacco material left over after extraction during the first heating step as defined above, where the tobacco material is heated to a temperature of 100°C to 160°C. Therefore, the residual tobacco material is the same tobacco material used in the heating step, but with the proportion of volatile compounds already removed as a result of the extraction. 【0024】 It has been found that including an alkali treatment step at this stage in the extraction method further optimizes the composition of the liquid tobacco extract that can be produced by the extraction method after the first heating step. The alkali treatment of the residual tobacco material before the second extraction allows the second heating step to extract a higher percentage of nicotine from the tobacco material so that the overall level of extracted nicotine is maximized. This is for the same reasons described above in relation to other embodiments of the present invention. 【0025】 The extraction of additional nicotine is carried out in a separate step following the first extraction of volatile compounds, so that the first extraction is not affected by the alkali treatment step. This allows for the optimization of the first extraction in relation to the yield of desirable flavor compounds derived from the tobacco material, while the second extraction favorably improves the overall nicotine yield. 【0026】 The alkali treatment process can be advantageously carried out within existing extraction equipment, minimizing its overall impact on the efficiency of the extraction process. The alkali treatment process can be implemented using readily available equipment and can be incorporated into existing extraction equipment without significant modifications. 【0027】 In addition to providing an improved nicotine yield as a result of including an alkali treatment step, the extraction method of the present invention advantageously provides an improved liquid tobacco extract having a significantly improved balance of desirable compounds over undesirable compounds using specific extraction conditions. In particular, the extraction method of the present invention provides a liquid tobacco extract in which the ratio of undesirable compounds to desirable compounds for the tobacco material is maximized. For example, by using a specific combination of defined extraction temperature and time, the level of nicotine compounds can be optimized while simultaneously minimizing the levels of undesirable compounds such as furans, carbonyls, phenols, and TSNA. 【0028】 The inventors of the present invention have found that, in contrast to the existing extraction processes described above, the method according to the present invention advantageously provides a liquid tobacco extract having a significantly higher content of compounds related to the flavor of heated tobacco, such as franeol. These compounds are either substantially absent or present in trace amounts in tobacco extracts obtained by the maceration process and typically contain little or no nicotine. These compounds are also generally absent or present in trace amounts in tobacco extracts obtained using a solvent, including under supercritical conditions. Similarly, tobacco essential oils obtained by a distillation process typically also have a very low content, if any, of such compounds related to the flavor of heated tobacco. 【0029】 The liquid tobacco extract obtained by the method according to the present invention shows a significant compositional difference compared to tobacco extracts obtained by existing extraction processes and can be used for the preparation of an e-liquid or, when heated, an aerosol having compositional and flavor characteristics different from currently available e-liquids. In particular, the liquid tobacco extract obtained by the method according to the present invention can be used to generate an aerosol that provides a heated tobacco taste more similar to that generated by conventional tobacco or by heating tobacco in a heat-not-burn device compared to an aerosol available from existing liquid nicotine compositions. 【0030】 The extraction method of the present invention enables the production of a liquid tobacco extract having an optimized level of nicotine and flavor compounds without adding such compounds after extraction. Thus, the resulting liquid tobacco extract can be advantageously used directly to provide a nicotine composition. The resulting liquid tobacco extract may also be modified by one or more additional processing steps or mixed with one or more additional components to form a nicotine composition. The nicotine composition may be for use in an electronic cigarette or other aerosol-generating system. 【0031】 As described above, an aerosol-generating system for delivering an aerosol to a user, comprising an atomizer configured to generate an inhalable aerosol from a liquid formulation such as a liquid nicotine composition, is known. 【0032】 The method for producing the liquid tobacco extract of the present invention can be effectively used for all types of tobacco and grades, including Burley tobacco, fire-cured tobacco, and Oriental leaf tobacco. The steps of the method can be easily adjusted to provide a consistent liquid tobacco extract for various blends of tobacco types. The extraction method is further suitable for various forms of tobacco materials. 【0033】 As described above, the method of the present invention incorporates an alkali treatment step, which is carried out on the tobacco material before heating or on the residual tobacco material. In either case, the alkali treatment step may be carried out in the same manner, and when referring to the alkali treatment of the tobacco material below, it should be considered applicable to the alkali treatment of the residual tobacco material as well, unless otherwise specified. 【0034】 Alkali treatment is carried out by applying an alkaline solution to the tobacco material to produce alkalized tobacco material. Preferably, the alkaline solution is sprayed onto the tobacco material so that the alkaline solution can be distributed as uniformly as possible throughout the tobacco material. 【0035】 In a method according to a first aspect of the present invention, the alkaline solution may be applied to tobacco material in an extraction chamber where the heating step is carried out in a separate or different apparatus. 【0036】 In a method according to a second aspect of the present invention, in which an alkaline treatment step is performed on tobacco material remaining after a first heating step, the alkaline solution may be applied to the residual tobacco material in the extraction chamber where the first heating step was performed. Alternatively, the residual tobacco material may be collected from the extraction chamber where the first heating step was performed, and the alkaline solution may be applied to the residual tobacco material in a different apparatus. Alternatively, the alkaline solution may be applied to the residual tobacco material when it is transferred from the first extraction chamber where the first heating step is performed to the second extraction chamber where the second heating step is performed. 【0037】 Preferably, the tobacco material is continuously circulated or stirred during the application of the alkaline solution so that the alkaline solution is homogeneously distributed. This optimizes the effect of the alkaline solution on the nicotine yield derived 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 more preferably at least about 9.5. Preferably, the pH of the alkalized tobacco material is 11 or less. 【0039】 "pH of alkalized tobacco material" refers to the pH of an aqueous suspension of alkalized tobacco material formed by suspending the alkalized tobacco material in water at a ratio of 1:20. The pH of the suspension is measured after a 30-minute immersion time. 【0040】 As described above, the alkali treatment step involves applying an alkaline solution to the tobacco material or residual tobacco material. A suitable alkaline solution may be selected, for example, depending on the desired pH of the tobacco material. Preferably, the alkaline solution is an aqueous solution of an alkaline agent. A preferred example of an alkaline solution suitable for the alkali treatment step is an aqueous solution of potassium carbonate. Other suitable alkaline solutions for use in the present invention include, but are not limited to, sodium hydroxide, sodium carbonate, and hydrogen peroxide. 【0041】 Preferably, the moisture content of the alkalized tobacco material is about 10% to about 20% by weight, more preferably about 12% to about 20% by weight, and more preferably about 12% to about 18% by weight, before the heating step. It has been found that providing an alkalized tobacco material having this preferred range of moisture content optimizes the extraction of volatile compounds during the subsequent heating step. Preferably, the desired moisture content of the alkalized tobacco material is provided by water in an alkaline solution so 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 may be added to the alkalized tobacco material separately from the alkaline solution. 【0042】 In a method according to a second aspect of the present invention, in which the alkaline treatment is performed on residual tobacco material derived from the first heating step, the residual tobacco material typically has a low moisture content after heating the tobacco material during the first heating step. In such a method, it is particularly important to restore the moisture content of the residual tobacco material to a level of 10 to 20 weight percent before the second heating step. As described above, this re-wetting 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, the method of the present invention involves heating a tobacco material under specific heating conditions to release volatile tobacco components, which are then collected and formed into a liquid tobacco extract. In an embodiment according to the first aspect of the present invention, in which the tobacco material is subjected to alkali treatment before the heating step, the alkalized tobacco material is heated as described below. 【0044】 During the heating process, the tobacco material is heated to an extraction temperature of approximately 100°C to 160°C. Below this range, insufficient concentrations 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, if the tobacco material is heated to a temperature above this defined range, unacceptably high levels of certain undesirable tobacco compounds may be released. 【0045】 The extraction temperature is preferably at least about 110 degrees Celsius, more preferably at least about 115 degrees Celsius, more preferably at least about 120 degrees Celsius, and more preferably at least 125 degrees Celsius. 【0046】 The extraction temperature is preferably about 150 degrees Celsius or lower, more preferably about 145 degrees Celsius or lower, even more preferably about 140 degrees Celsius or lower, and most preferably about 135 degrees Celsius or lower. 【0047】 For example, the extraction temperature may be approximately 110°C to 150°C, or approximately 120°C to 140°C, or approximately 125°C to 135°C, or approximately 130°C. An extraction temperature of approximately 130°C has been found to provide a particularly optimized ratio of desirable to undesirable compounds in the liquid tobacco extract. 【0048】 The tobacco material is heated at a certain extraction temperature for at least about 30 minutes, more preferably at least about 40 minutes, more preferably at least about 50 minutes, and more preferably at least about 60 minutes. This extraction time is long enough to efficiently extract the desired tobacco flavor compounds and provide a liquid tobacco extract capable of producing an aerosol having the desired flavor characteristics. By including an alkali treatment step, the heating step can be carried out relatively quickly, potentially allowing heating for a shorter duration than is typically required in conventional extraction processes. 【0049】 Preferably, the tobacco material is heated at a certain extraction temperature for 180 minutes or less, more preferably about 120 minutes or less. 【0050】 For example, tobacco material may be heated for approximately 30 to 180 minutes, or approximately 30 to 120 minutes, or approximately 40 to 180 minutes, or approximately 40 to 120 minutes, or approximately 50 to 180 minutes, or approximately 50 to 120 minutes, or approximately 60 to 180 minutes, or approximately 60 to 120 minutes. 【0051】 The heating time shown above corresponds to the duration of time the tobacco material is heated to the extraction temperature, and does not include the time required to raise the temperature of the tobacco material to the extraction temperature. 【0052】 In the first embodiment of the present invention, the tobacco material is subjected to an alkali treatment step before the first heating step, the amount of nicotine extracted from the alkalized tobacco material during the heating step is preferably at least about 10 grams / kg of dry tobacco material, more preferably at least about 12 grams / kg of dry tobacco material. The extraction yield of this nicotine is significantly higher than that obtained using an equivalent extraction method, except that which does not include the alkali treatment step before the heating step, as shown in the following example. 【0053】 A second aspect of the present invention, in which residual tobacco material is subjected to an alkaline treatment step, further includes a second heating step for removing volatile compounds, particularly nicotine, from the residual tobacco material. 【0054】 In this method, during the first heating step, the tobacco material is heated to an extraction temperature of approximately 100 to 160 degrees Celsius. Preferably, the extraction temperature in the first extraction step is at least approximately 110 degrees Celsius, more preferably at least approximately 115 degrees Celsius, more preferably at least approximately 120 degrees Celsius, and more preferably at least approximately 125 degrees Celsius. 【0055】 Preferably, the extraction temperature in the first extraction step is about 150 degrees Celsius or lower, more preferably about 145 degrees Celsius or lower, more preferably about 140 degrees Celsius or lower, and most preferably about 135 degrees Celsius or lower. 【0056】 For example, the extraction temperature in the first extraction step may be approximately 110°C to 150°C, or approximately 120°C to 140°C, or approximately 125°C to 135°C, or approximately 130°C. An extraction temperature of approximately 130°C has been found to provide a particularly optimized ratio of desirable to undesirable compounds in the liquid tobacco extract. 【0057】 During the first heating step, the tobacco material is heated at a certain extraction temperature for at least about 90 minutes, more preferably at least about 120 minutes. Preferably, the tobacco starting material is heated at a certain extraction temperature for about 270 minutes or less, more preferably about 180 minutes or less. For example, the tobacco material may be heated for about 90 to about 270 minutes, or about 90 to about 180 minutes, or about 120 to about 270 minutes, or about 120 to about 180 minutes. 【0058】 In the second heating step, the alkalized tobacco material is heated to an extraction temperature of approximately 100°C to 160°C. The temperature in the second heating step may be the same as or different from the temperature selected for the first heating step. 【0059】 Preferably, the extraction temperature in 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 more preferably at least about 125 degrees Celsius. 【0060】 Preferably, the extraction temperature in the second heating step is about 150 degrees Celsius or lower, more preferably about 145 degrees Celsius or lower, more preferably about 140 degrees Celsius or lower, and more preferably about 135 degrees Celsius or lower. 【0061】 For example, the extraction temperature in the second heating step could be approximately 110°C to 150°C, or approximately 120°C to 140°C, or approximately 125°C to 135°C, or approximately 130°C. 【0062】 In such a method, which includes a second heating step, the alkalized tobacco material is preferably heated in the second heating step for at least 15 minutes, more preferably at least 20 minutes, more preferably at least 30 minutes, and more preferably at least 40 minutes. The second heating step is usually shorter than the first heating step. Preferably, during the second heating step, the alkalized tobacco material is heated for about 120 minutes or less, more preferably about 90 minutes or less. For example, the alkalized tobacco material may be heated for about 15 to about 120 minutes, or about 15 to about 90 minutes, or about 20 to about 120 minutes, or about 20 to about 90 minutes, or about 30 to about 120 minutes, or about 30 to about 90 minutes, or about 40 to about 120 minutes, or about 40 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 may be carried out in the same extraction chamber as the first heating step, or in a second extraction chamber. If the two extraction chambers are used for separate heating steps, the extraction chambers may be optionally connected to achieve a continuous flow of tobacco material through the extraction apparatus. 【0065】 In a method according to a second aspect of the present invention, in which the alkali treatment step is performed on the residual tobacco material after the 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 / kg of dry tobacco material, more preferably at least about 2 grams / kg of dry tobacco material. This nicotine yield is added to the nicotine extracted from the tobacco material during the first heating step. 【0066】 For each heating step, the extraction temperature and heating time may be selected within the range defined above, depending on factors such as the type of tobacco, other possible components of the tobacco material, the desired level of nicotine, 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 according to the desired properties of the aerosol produced from the liquid tobacco extract. In particular, the proportion of specific tobacco compounds in the liquid tobacco extract can be adjusted to some extent through the selection of extraction parameters in order to maximize the ratio of desirable to undesirable tobacco compounds in the liquid tobacco extract. 【0067】 For certain tobacco compounds, the variation in compound release levels with respect to extraction temperature during the extraction process can be easily determined for any given tobacco material. For example, it has been shown that the level of nicotine released from tobacco material typically increases with increasing extraction temperature. The rate of increase has been found to vary depending on the type of tobacco. 【0068】 Furthermore, it has been found that the levels of desirable tobacco flavor compounds, such as β-damascenone and β-ionone, released from tobacco material increase as the extraction temperature rises to a specific peak extraction temperature, after which the levels begin to decrease. The peak extraction temperature for such flavor compounds is typically in the range of 120°C to 160°C, so that the extraction method of the present invention can effectively optimize the levels of desirable flavor compounds. 【0069】 Numerous undesirable tobacco compounds have been found to increase slowly with increasing extraction temperature up to a threshold temperature, beyond which a rapid increase is observed. This applies, for example, to the concentrations of phenolic compounds, TSNA, and certain pyrazines, and in the case of bright tobacco, to the concentrations of furan and formaldehyde. In many cases, the threshold temperature is in the range of 120°C to 160°C, and therefore, 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 in the liquid tobacco extract of at least 0.1 weight percent, more preferably at least about 0.2 weight percent. 【0071】 Preferably, in the method according to a second aspect of the present invention, the extraction temperature and / or extraction time of the heating step, or both, is selected to provide a weight ratio of at least about 0.25 (β-ionone + β-damascenone) to (phenol) in the liquid tobacco extract. 【0072】 β-Damascenone and β-Ionone are desirable compounds associated with tobacco flavor. It has also been found that the amounts of β-Damascenone and β-Ionone released from tobacco material increase as the extraction temperature rises to a certain peak extraction temperature, after which the levels begin to decrease. The peak extraction temperature for such flavor compounds is typically in the range of 120°C to 160°C, so that the extraction method can effectively adjust and control the levels of the desired flavor compounds. 【0073】 Preferably, in the method according to the second aspect of the present invention, the extraction temperature or extraction time of the heating step, or both the extraction temperature and extraction time, is at least about 5 x 10 in the liquid tobacco extract. -4 Selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to (nicotine). 【0074】 In the method according to the present invention, where the extraction temperature is selected to provide a ratio within the range described above, it has been found that a particularly good sensory profile can be achieved when heating a nicotine composition prepared from a liquid tobacco extract to generate an aerosol. 【0075】 Suitable heating methods for heating tobacco materials are known to those skilled in the art and include, but are not limited to, dry distillation, steam distillation, vacuum distillation, flash distillation, and thin-film steam distillation. 【0076】 It is preferable that one or more heating steps be carried out in an inert atmosphere. It is preferable that a flow of an inert gas, such as nitrogen, passes through the tobacco material during the heating process. In some cases, a combination flow of an inert gas and water or vapor may be used. Adding water or vapor to the tobacco during extraction has been found to increase the yield of extracted components. However, adding too much water or vapor can lead to processing difficulties such as stickiness of the tobacco material. 【0077】 The volatile tobacco compounds are released into a stream of inert gas during the heating process so that the inert gas (or a combination of inert gas and water or vapor) acts as a carrier for the volatile components. The inert gas flow rate may be optimized based on the scale and shape of the extraction chamber. Relatively high flow rates of the inert gas can favorably improve the efficiency of extraction from the tobacco material. 【0078】 Generally, when tobacco material is heated, any moisture present in the tobacco material is also released along with volatile compounds in the form of vapor. 【0079】 The flow of inert gas helps to remove vapors produced by the evaporation of moisture from the tobacco material, and volatile compounds, particularly nicotine or flavor-related compounds, or both, from the extraction equipment. 【0080】 Furthermore, the use of an inert gas (such as nitrogen) flow under slight overpressure within the extraction equipment has the advantage of preventing the presence of oxygen within the equipment. This is desirable in that it prevents the risk of the tobacco material burning, even partially, during the heating process. Uncontrolled combustion of tobacco material is obviously undesirable as it would pose a major safety risk in the manufacturing environment. However, the inventors have found that even limited and partial combustion of tobacco material can lead to a decrease in the quality of the tobacco extract obtainable by this method (which would be undesirable). 【0081】 While we do not wish to be bound by theory, it is understood that preventing the combustion of tobacco material also prevents the formation of any undesirable combustion byproducts. Furthermore, by preventing conditions that would promote the combustion of tobacco material, the tobacco material is effectively heated under conditions that, to some extent, mimic the conditions under which tobacco-containing substrates (e.g., homogenized tobacco material) are typically heated in "heated non-combustible" articles. As a result, it is advantageously supported for consumers to selectively extract volatile species that contribute to the flavor associated with heated tobacco. 【0082】 Therefore, performing the heating process in an inert atmosphere advantageously enhances extraction efficiency, product quality, and manufacturing safety. 【0083】 Heating tobacco material in an inert gas flow has the additional benefit that the flow of inert gas containing volatile compounds can be more easily directed towards a container containing an extraction solvent, such as a non-aqueous extraction liquid solvent. 【0084】 Optionally, the heating process may be carried out under vacuum. This removes any oxygen present in the extraction chamber, which is advantageous as it can prevent the reaction of the tobacco material or volatile compounds produced during heating of the tobacco material with oxygen. The removal of oxygen also prevents any combustion of the tobacco material, as described above. 【0085】 The method according to the present invention may further include a step of spraying water into the extraction chamber during the heating step. This has been found to improve heat exchange during the heating step, which is thought to be due to the turbulence generated in the extraction chamber as a result of the evaporation of the sprayed water. As a result of the improved heat exchange, it has been found that including the step of spraying water into the extraction chamber during the heating step leads to a further improvement in nicotine yield, as well as an increase in the yield of certain desirable flavor compounds derived from tobacco material. 【0086】 A spray of atomized water can be generated using any suitable means and discharged into the extraction chamber. 【0087】 The flow rate at which atomized water is sprayed into the extraction chamber can be adjusted, for example, according to the flow rate of tobacco material in the extraction chamber. For instance, the average flow rate at which atomized water is sprayed into the extraction chamber may be approximately 3 percent to 30 percent of the flow rate of 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 more preferably at least about 3 bar. 【0089】 Methods for atomizing water will be known to those skilled in the art. In some embodiments, water can be atomized by a flow of compressed inert gas, such as air. In other embodiments, water can be atomized without a gas flow due to the pressure within the spray nozzle. 【0090】 Liquid tobacco extracts can be produced from tobacco material consisting of a single type of natural tobacco. Alternatively, the tobacco material may contain 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 produced from the liquid tobacco extract. For example, if it is desired to provide a relatively high level of nicotine, the proportion of Burley tobacco can be increased. 【0091】 The term “natural tobacco” is used herein to describe any part of any plant member of the genus Nicotiana, including but not limited to leaves, midribs, stems, and petioles, in relation to the present invention. In particular, natural tobacco may include fire-dried tobacco material, Burley tobacco material, Oriental leaf tobacco material, Maryland tobacco material, dark tobacco material, dark fire-dried tobacco material, Rustica tobacco material, and other rare or specialty tobacco-derived materials, or blends thereof. As will be described in more detail below, tobacco material may be whole (e.g., whole tobacco leaves), or shredded, cut, or ground. 【0092】 If it is desired to produce a liquid tobacco extract from a combination of two or more different types of tobacco, the types of tobacco may be heated separately at different extraction temperatures within a defined range of 100 to 160 degrees Celsius, or the mixture of tobacco types may be heated together at a single extraction temperature within that range. 【0093】 The tobacco material may be a solid tobacco material such as powder, leaf scraps or fragments, or intact leaves. Alternatively, the tobacco material may be a liquid tobacco material such as dough, gel, slurry, or suspension. 【0094】 The tobacco material 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】 In the process of preparing tobacco material, it is preferable that the tobacco be crushed or cut in order to reduce the size of the tobacco particles in the tobacco material. This may be advantageous in that it can improve the homogeneity of heating the tobacco material and the efficiency of extraction. 【0096】 The tobacco material may be optionally dried before the heating step to reduce its moisture content. Drying of the tobacco material may be carried out by any suitable chemical or physical drying process. Alternatively, water may be added to the tobacco material before the heating step to increase its moisture content. 【0097】 In certain embodiments of the present invention, the step of preparing a tobacco material may include the step of impregnating the tobacco material with an aerosol-forming agent. If this impregnation of the tobacco material is performed before the heating step, this may advantageously increase the amount of certain desirable tobacco compounds released from the tobacco material upon heating. For example, impregnation of tobacco material with glycerin has been shown to advantageously increase the amount of nicotine extracted from the tobacco material. In another embodiment, impregnation of tobacco starting material with a non-aqueous extraction solvent, which is also an aerosol-forming agent such as propylene glycol, vegetal glycerin, 1,3-propanediol, triacetin, or a mixture thereof, has been found to advantageously increase the amount of flavor compounds extracted from the tobacco material. 【0098】 In some embodiments, the tobacco material consists of natural tobacco that has not been subjected to any pretreatment process, for example, to adjust the moisture content. Thus, the moisture content of the tobacco material may be about 10-20 weight percent (typically found in natural tobacco material). In other embodiments, the tobacco material may contain added water, as described above. 【0099】 Alternatively or additionally, the tobacco material may contain one or more additional components, such as a non-aqueous solvent. An example of a suitable solvent is propylene glycol. 【0100】 Therefore, the tobacco material may contain at least about 40 weight percent of natural tobacco material, or at least about 60 weight percent of natural tobacco material, or at least about 80 weight percent of natural tobacco material, or at least about 90 weight percent of natural tobacco material, or at least about 95 weight percent of natural tobacco material. 【0101】 The moisture content of the tobacco starting material may be at least about 3 weight percent. Preferably, the moisture content of the tobacco starting material is at least about 5 weight percent. More preferably, the moisture content of the tobacco starting material is at least about 5 weight percent. Naturally, the "moisture content in the tobacco starting material" may include both water that is essentially present in the natural tobacco material and any added water. 【0102】 The moisture content of the tobacco starting material may be about 60 weight percent or less. Preferably, the moisture content of the tobacco starting material is about 20 weight percent or less. More preferably, the moisture content of the tobacco starting material is about 12 weight percent or less. 【0103】 In some embodiments, the moisture content of the tobacco starting material may be about 3% to about 60% by weight, more preferably about 3% to about 20% by weight, and even more preferably about 3% to about 12% by weight. In other embodiments, the moisture content of the tobacco starting material may be about 5% to about 60% by weight, more preferably about 5% to about 20% by weight, and even more preferably about 5% to about 12% by weight. In further embodiments, the moisture content of the tobacco starting material may be about 8% to about 60% by weight, more preferably about 8% to about 20% by weight, and even more preferably about 8% to about 12% by weight. 【0104】 In some embodiments, the non-aqueous solvent content may be at least about 5 weight percent, or at least about 10 weight percent, or at least about 15 weight percent, or at least about 20 weight percent, or at least about 25 weight percent, or at least about 30 weight percent, or at least about 35 weight percent, or at least about 40 weight percent. 【0105】 Optionally, the tobacco material may be enzymatically digested before the heating process. This has been shown to provide a significant increase in the yield of certain flavor compounds from the tobacco material. 【0106】 The tobacco material may optionally be analyzed before the heating step to determine its composition, for example, the content of reducing sugars such as alkaloids. This information regarding the composition can be useful in selecting an appropriate extraction temperature. 【0107】 The method according to the present invention may further include a step of microwave heating of tobacco material during at least one step of the method. The tobacco material may be microwave heated before the heating step, during the pretreatment step. Alternatively or additionally, the tobacco material may be microwave heated during the main heating step, in place of or in combination with conventional heating. 【0108】 It has been found that including a microwave heating step in the extraction method of the present invention leads to a further improvement in nicotine extraction yield. 【0109】 During heating of tobacco material, volatile compounds are released from the tobacco material in gaseous form. These volatile compounds are collected using any suitable technique. If, as described above, the tobacco material is heated in a flow of inert gas, the volatile compounds are collected from the inert gas flow. Different collection methods will be well known to those skilled in the art. 【0110】 In certain preferred embodiments, the step of collecting volatile compounds employs an absorption technique to confine the volatile compounds in a non-aqueous extractive liquid solvent. For example, an inert gas stream containing the volatile compounds may be directed into a container of the non-aqueous extractive liquid solvent. The non-aqueous extractive liquid solvent is preferably an aerosol-forming agent such as triacetin, glycerin, 1,3-propanediol, propylene glycol, or a combination thereof. Using an aerosol-forming agent as the liquid solvent is potentially beneficial because the aerosol-forming agent can be retained as a diluent in the final liquid tobacco extract. This means that an additional step to remove the non-aqueous extractive solvent is not necessarily required. 【0111】 As used herein in relation to the present invention, the term “aerosol-forming compound” refers to a compound or mixture of compounds that facilitates aerosol formation in use and is preferably substantially resistant to thermal decomposition at the operating temperature of the aerosol-generating article or apparatus. Examples of suitable aerosol-forming compounds include polyhydric alcohols (such as propylene glycol, triethylene glycol, 1,3-propanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic acids, dicarboxylic acids, or polycarboxylic acids (such as dimethyl dodecanediate and dimethyl tetradecanediate). 【0112】 Non-aqueous liquid solvents are preferably maintained at a temperature below 0 degrees Celsius to optimize the transfer of volatile compounds into the liquid solvent. Non-aqueous extraction solvents are preferably maintained at a temperature of -10 degrees Celsius or higher. Temperatures below these values ​​may result in undesirable freezing. 【0113】 In alternative, preferred embodiments, the step of collecting volatile compounds may be carried out using a condensation technique in which the volatile compounds are condensed and the condensate of volatile compounds is collected. The condensation of volatile compounds may be carried out, for example, using any suitable apparatus in a cooling column. Preferably, the obtained condensate is added to a liquid aerosol former, preferably propylene glycol. 【0114】 The addition of a liquid aerosol-forming agent, particularly propylene glycol, during the collection process can advantageously prevent condensed volatile compounds from separating into two phases or forming emulsions, as is the case with some tobacco components. While not intended to be theoretically bound, the inventors observed that the solubility of tobacco components in aqueous extracts (hydrolates) (i.e., aqueous fractions of naturally derived liquid tobacco extracts) depends primarily on their polarity, concentration, and the pH of the aqueous extract (hydrolate), 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 oily substances can aggregate at different locations in the capture and drying equipment, where the third and subsequent steps of the method are carried out, respectively. The addition of a liquid aerosol-forming agent, such as propylene glycol, helps prevent the formation of such layers and is advantageous for homogenizing the naturally derived liquid tobacco extract. This, in turn, helps prevent the loss of desirable flavor-related compounds during the fourth (drying) step, during which time these compounds may unnecessarily accumulate on the equipment surface. 【0115】 Furthermore, the liquid aerosol form, regardless of its polarity and volatility, is advantageous in capturing flavor-related compounds. Moreover, during any subsequent drying process, the liquid aerosol form helps prevent the loss of the most volatile fractions and is advantageous in selectively removing excess water from naturally derived liquid tobacco extracts to obtain concentrated tobacco extracts. 【0116】 The use of propylene glycol as an aerosol former in the collection process has the added advantage that propylene glycol exerts antimicrobial activity by reducing the water activity of the aqueous solution. Therefore, by adjusting the propylene glycol content in the liquid tobacco extract, it is possible to ensure that the extract is virtually free from microbial activity. 【0117】 As a further alternative, the process of collecting 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 into a liquid solvent. 【0118】 In the method of the present 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. The "collected volatile compounds" typically include 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 contain more than about 25 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. In some embodiments, the liquid tobacco extract may contain more than about 30 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract, or more than about 35 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. 【0120】 The liquid tobacco extract may contain about 65 percent or less of a non-aqueous extraction solvent based on the weight of the liquid tobacco extract. In some embodiments, the liquid tobacco extract may contain 60 percent or less of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract, or 55 percent or less of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. 【0121】 In some embodiments, the liquid tobacco extract may comprise about 25 weight percent to about 65 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 25 weight percent to about 60 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 25 weight percent to about 55 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. 【0122】 In other embodiments, the liquid tobacco extract may comprise about 30 weight percent to about 65 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 30 weight percent to about 60 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 30 weight percent to about 55 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. 【0123】 In further embodiments, the liquid tobacco extract may comprise about 35 weight percent to about 65 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 35 weight percent to about 60 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The liquid tobacco extract may comprise about 35 weight percent to about 55 weight percent of the non-aqueous extraction solvent based on the weight of the liquid tobacco extract. The non-aqueous extraction solvent is preferably triacetin, glycerin, propylene glycol, 1,3-propanediol, or a mixture 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 (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to (nicotine) in the liquid tobacco extract is at least about 5 x 10 -4 That is the case. 【0126】 As described above, when volatile compounds are collected by absorption in a liquid solvent, 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 may be done, for example, to reach a desired concentration of nicotine or flavor compounds. Drying may be carried out using any suitable means, including but not limited to desiccation, molecular sieving, freeze-drying, phase separation, distillation, membrane permeation, controlled crystallization and filtration of water, reverse hygroscopicity, ultracentrifugation, liquid chromatography, reverse osmosis, or chemical drying. 【0127】 In a preferred embodiment, the solution of the volatile compound in the liquid solvent is concentrated by drying. 【0128】 In other words, a concentrated tobacco extract is obtained by heating a solution of volatile compounds in a liquid solvent to evaporate at least some of the water. For this purpose, the solution of volatile compounds in a liquid solvent may be heated to a certain temperature and for a certain period of time such that the water content in the tobacco extract is reduced by at least about 60 percent. 【0129】 A partially dried concentrated tobacco extract can be considered a primary product of the method according to the present invention. Depleted tobacco material, from which most of the volatile species and moisture content have been extracted during heating in the second step, can be considered a by-product of the method. Such depleted tobacco material may typically have a moisture content of about 1 to 5 weight percent, preferably about 2 to 3 weight percent. 【0130】 In one embodiment, a solution of a volatile compound in a liquid solvent is heated under vacuum, preferably at a temperature of at least about 70 degrees Celsius. In another embodiment, a solution of a volatile compound in a liquid solvent is heated under an airflow, preferably an airflow 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 present invention. One such concentrated tobacco extract of natural origin typically contains less than about 20 percent by weight of water. 【0131】 Alternatively, if volatile compounds are collected 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】 The process of forming a liquid tobacco extract may optionally include a filtration step. 【0133】 Optionally, the process of forming a liquid tobacco extract may include a blending process in which extracts derived from different tobacco materials are combined. 【0134】 Optionally, the process of forming a liquid tobacco extract may involve 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 additives. 【0135】 In an embodiment according to a second aspect of the present invention, in which the alkali treatment step is performed on residual tobacco material derived from a first heating step, two separate liquid tobacco extracts are produced during the extraction method: a first liquid tobacco extract derived from the first heating step of the tobacco material, and a second liquid tobacco extract derived from the second heating step of the alkalized tobacco material. Preferably, such a method further includes a step of combining the first liquid tobacco extract and the second liquid tobacco extract. 【0136】 In certain embodiments, nicotine may be isolated from a second liquid tobacco extract, and at least a portion of the isolated nicotine may be added to the first liquid tobacco extract. This results in 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 liquid tobacco extracts prepared by the method of the present invention as described in detail above. As described above, the method of the present invention advantageously prepares natural liquid tobacco extracts having a very desirable ratio of desired tobacco compounds, such as nicotine and flavor compounds, to undesirable tobacco compounds. 【0138】 Liquid tobacco extracts are particularly suitable for preparing nicotine compositions, such as liquid nicotine compositions or gel nicotine compositions, for use in aerosol generating systems. In such aerosol generating systems, the nicotine composition is typically heated within the aerosol generator. 【0139】 As used herein, the term “aerosol generating device” refers to a device comprising a heating element that interacts with a nicotine composition incorporating a liquid tobacco extract, such as by a method according to the present invention to produce an aerosol. During use, volatile compounds are released from the nicotine composition by heat transfer and taken into the air drawn through the aerosol generating device. As the released compounds cool, they condense to form an aerosol, which is inhaled by the consumer. 【0140】 Upon heating of the nicotine composition containing the liquid tobacco extract according to the present invention, an aerosol containing volatile compounds collected from the tobacco material during the extraction process is released. By controlling the composition of the liquid tobacco extract through the control of extraction parameters, it is possible to adjust the composition and properties of the resulting aerosol, which is prepared from the liquid tobacco extract and delivered to the consumer. 【0141】 The nicotine composition may be a liquid tobacco extract obtained from the extraction process according to the present invention without the addition of further nicotine. The nicotine composition may be a liquid tobacco extract obtained from the extraction process according to the present invention without the addition of further flavor compounds. The nicotine composition may be a liquid tobacco extract obtained from the extraction process according to the present invention without the addition of further furaneol. The nicotine composition may be a liquid tobacco extract obtained from the extraction process according to the present invention without the addition of further solvents. 【0142】 Alternatively, the liquid tobacco extract may be subjected to additional processing steps to form a nicotine composition. Even when subjected to such additional steps, the nicotine composition can be formed without the need to add further nicotine or flavoring compounds. 【0143】 Preferably, the liquid tobacco extract may be concentrated in the drying step described above to form a concentrated tobacco extract, and the concentrated tobacco extract may be used to form a nicotine composition. 【0144】 Preferably, the concentrated tobacco extract contains 8% to 15% by weight of water, based on the weight of the concentrated tobacco extract. 【0145】 The drying step provides a concentrated tobacco extract that 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 triacetin, glycerin, propylene glycol, 1,3-propanediol, or a mixture thereof. 【0146】 The drying process provides a concentrated tobacco extract that may have a nicotine content of at least about 0.2 weight percent of nicotine, preferably about 0.5 weight percent to about 12 weight percent of nicotine, and most preferably about 2 weight percent to about 8 weight percent of nicotine. 【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 contain at least about 10 weight percent of liquid tobacco extract. Preferably, the nicotine composition contains at least about 20 weight percent of liquid tobacco extract. More preferably, the nicotine composition contains at least about 30 weight percent of liquid tobacco extract. In a preferred embodiment, the nicotine composition contains at least about 40 weight percent of liquid tobacco extract, more preferably at least about 50 weight percent of liquid tobacco extract, and even more preferably at least about 60 weight percent of liquid tobacco extract. In a particularly preferred embodiment, the nicotine composition contains at least about 65 weight percent of liquid tobacco extract, more preferably at least about 70 weight percent of liquid tobacco extract, even more preferably at least about 75 weight percent of liquid tobacco extract, and most preferably at least about 80 weight percent of liquid tobacco extract. 【0150】 In some embodiments, the liquid tobacco extract is a concentrated tobacco extract. The nicotine composition may contain at least about 10 weight percent of concentrated tobacco extract, at least about 20 weight percent of concentrated tobacco extract, at least about 30 weight percent of concentrated tobacco extract, at least about 40 weight percent of concentrated tobacco extract, at least about 50 weight percent of concentrated tobacco extract, preferably at least about 60 weight percent of concentrated tobacco extract, more preferably at least about 70 weight percent of concentrated tobacco extract, even more preferably at least about 75 weight percent of concentrated tobacco extract, and most preferably at least about 80 weight percent 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, and even more preferably about 80% to about 85% by weight of liquid tobacco extract. 【0154】 The nicotine composition may contain up to about 100 weight percent of liquid tobacco extract. In some embodiments, the nicotine composition may be formed directly from the liquid tobacco extract without the need for additional non-aqueous solvents, flavorings, or nicotine additions. That is, the nicotine composition may contain 100 weight percent of liquid tobacco extract. In some embodiments, the liquid tobacco extract is a concentrated tobacco extract, and the nicotine composition may contain 100 weight percent of concentrated tobacco extract. In embodiments in which the nicotine composition contains 100 weight percent of liquid tobacco extract or 100 weight percent of concentrated tobacco extract, no additional non-aqueous solvents are present. 【0155】 Alternatively, in some embodiments, the nicotine composition containing the liquid tobacco extract may contain an additional non-aqueous solvent. The additional non-aqueous solvent is a non-aqueous solvent added after the extraction step. The additional non-aqueous solvent is 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 containing the concentrated tobacco extract may contain an additional non-aqueous solvent. 【0156】 The additional non-aqueous solvent may be an aerosol-forming agent. Preferably, the additional non-aqueous solvent is triacetin, glycerin, propylene glycol, 1,3-propanediol, or a mixture thereof. 【0157】 In embodiments in which the nicotine composition contains an additional non-aqueous solvent, the nicotine composition may contain 90% by weight or less of the additional non-aqueous solvent. Preferably, the nicotine composition contains 80% by weight or less of the additional non-aqueous solvent. More preferably, the nicotine composition contains 70% by weight or less of the additional non-aqueous solvent. In preferred embodiments, the nicotine composition contains 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 contains 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 the liquid tobacco extract. 【0158】 In a nicotine composition prepared by means of the method according to the present invention, at least 50 weight percent of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80 weight percent of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. More preferably, at least 90 weight percent of the nicotine content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. 【0159】 In a nicotine composition prepared by means of the method according to the present 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, can be obtained from a 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, can be obtained from a tobacco extract rather than being added after extraction. 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, can be obtained from a tobacco extract rather than being added after extraction. 【0160】 In a nicotine composition prepared by means of the method according to the present invention, at least 50 weight percent of the water content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80 weight percent of the water content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. More preferably, at least 90 weight percent of the water content in the nicotine composition, based on the total weight of the nicotine composition, can be derived from a tobacco extract rather than being added after extraction. 【0161】 In a nicotine composition prepared by means of the method according to the present invention, at least 50 weight percent of the desired tobacco flavor content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. In a preferred embodiment, at least 80 weight percent of the desired flavor content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained from a tobacco extract rather than being added after extraction. More preferably, at least 90 weight percent of the desired flavor content in the nicotine composition, based on the total weight of the nicotine composition, can be obtained 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, if present, additional non-aqueous solvents. The nicotine composition may contain a total non-aqueous solvent content of about 10% to about 95% by weight. Preferably, the nicotine composition contains a total non-aqueous solvent content of about 50% to about 95% by weight, for example, about 65% to about 95%, more preferably about 70% to about 90%, and most preferably about 80% to about 90%. The non-aqueous solvent is preferably triacetin, glycerin, propylene glycol, 1,3-propanediol, or a mixture thereof. 【0163】 The nicotine composition may contain a total propylene glycol content of about 10% to about 95% by weight. The nicotine composition may contain a total propylene glycol content of about 20% to about 95% by weight, for example, 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. 【0164】 The nicotine composition may contain a total triacetin content of about 10% to about 95% by weight. The nicotine composition may contain a total triacetin content of about 20% to about 95% by weight, for example, about 50% to about 95% by weight, about 70% to about 90% by weight, or about 65% to about 95% by weight, or about 80% to about 90% by weight. 【0165】 The nicotine composition may contain a total glycerin content of about 10% to about 95% by weight. The nicotine composition may contain a total glycerin content of about 20% to about 95% by weight, for example, 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. 【0166】 The nicotine composition may contain a total 1,3-propanediol content of about 10% to about 95% by weight. The nicotine composition may contain a total 1,3-propanediol content of about 20% to about 95% by weight, for example, about 50% to about 95% by weight, or about 65% to about 95% by weight, or about 80% to about 90% by weight. 【0167】 The nicotine composition of the present invention contains at least 0.2 weight percent of nicotine. More preferably, the nicotine content in the nicotine composition liquid tobacco extract is at least about 0.4 weight percent. The nicotine composition may have a nicotine content of about 12 weight percent or less, for example, about 10 weight percent or less, preferably about 8 weight percent or less, more preferably about 5 weight percent or less, and preferably about 3.6 weight percent or less. Most preferably, the nicotine composition contains about 0.4 weight percent to 3.6 weight percent of nicotine based on the weight of the nicotine composition. 【0168】 The nicotine composition may contain 1% to 85% by weight of water. The nicotine composition may contain 2% to 50% by weight of water. The nicotine composition may contain 3% to 30% by weight of water. The nicotine composition may contain 5% to 25% by weight of water. The nicotine composition may contain 8% to 20% by weight of water. The nicotine composition preferably contains 10% to 15% by weight of water. 【0169】 In some embodiments, the nicotine composition may contain one or more water-soluble organic acids. As used herein in connection with the present invention, the term "water-soluble organic acid" refers to an organic acid having water solubility of about 500 mg / ml or more at 20°C. 【0170】 One or more water-soluble organic acids can, advantageously, bind to nicotine in the liquid tobacco extract by forming one or more nicotine salts. These one or more nicotine salts can, advantageously, be dissolved and stabilized in water present in the liquid tobacco extract or in a non-aqueous solvent. This can, advantageously, reduce nicotine adsorption in the upper airways and enhance nicotine delivery and retention in the lungs, as discussed above. 【0171】 Preferably, the water-soluble organic acid content of the nicotine composition is about 2% by weight or more. More preferably, the water-soluble organic acid content of the nicotine composition is about 3% by weight or more. 【0172】 The water-soluble organic acid may be acetic acid. 【0173】 Exogenous acetic acid is acetic acid added from a source other than tobacco plant material and is not naturally occurring acetic acid in tobacco plants that is separated, removed, or derived from tobacco plant material using extraction conditions and techniques. 【0174】 When acetic acid is added to a liquid tobacco extract to form a nicotine composition, the total content of acetic acid in the nicotine composition, including both exogenous and endogenous acetic acid, is preferably about 0.01% to about 8% by weight, for example, about 0.03% to about 8%, about 0.3% to about 8%, about 2% to about 8%, or about 3% to about 8%. More preferably, the total content of acetic acid is about 0.01% to about 6% by weight, for example, about 0.03% to about 6%, about 0.3% to about 6%, about 2% to about 6%, or about 3% to about 6%. 【0175】 Preferably, the water-soluble organic acid content of the nicotine composition is about 8% by weight or less. More preferably, the water-soluble organic acid content of the nicotine composition is about 6% by weight or less. 【0176】 Preferably, the water-soluble organic acid content of the nicotine composition is about 2% to about 8% by weight. For example, the water-soluble organic acid content of the nicotine composition may be about 2% to about 6% by weight. 【0177】 More preferably, the water-soluble organic acid content of the nicotine composition is about 3% to about 8% by weight. For example, the water-soluble organic acid content of the nicotine composition may be about 3% to about 6% by weight. 【0178】 The nicotine composition may contain one or more non-tobacco flavoring agents. A suitable non-tobacco flavoring agent is, but is not limited to, menthol. 【0179】 Preferably, the nicotine composition contains about 4% by weight or less of non-tobacco-derived flavoring agents. More preferably, the nicotine composition contains about 3% by weight or less of non-tobacco-derived flavoring agents. For example, using the liquid tobacco extract produced by the method of the present invention, a nicotine composition containing 10 to 20 mg of nicotine per milliliter can be prepared without the need for nicotine addition. 【0180】 A nicotine composition suitable for use in an aerosol generating system may include a liquid tobacco extract prepared by the method according to the present invention, in combination with water and an additional aerosol-forming agent. The nicotine composition may, for example, contain about 10% to about 20% by weight of water. 【0181】 The nicotine composition containing the liquid tobacco extract according to the present invention may be provided in a cartridge for use in an aerosol generating system. The cartridge may comprise 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 comprise, for example, a heater and a liquid transport element configured to move the nicotine composition to the heater. The liquid transport element may include a capillary wick. Alternatively, the atomizer may be a non-thermal atomizer configured to generate an aerosol from the nicotine composition by means other than heating. The non-thermal atomizer may be, for example, an impingement jet atomizer, an ultrasonic atomizer, or a vibrating mesh atomizer. 【0182】 A cartridge containing a nicotine composition formed from the liquid tobacco extract of the present invention may 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】 One embodiment of the present invention will be explained further here, although only as an example. 【0184】 Comparative Example In a method according to a first aspect of the present invention, tobacco material is cut to form tobacco fragments having dimensions of 2.5 mm × 2.5 mm, and the tobacco fragments are loaded into an extraction chamber without compression. An aqueous solution of potassium carbonate is sprayed onto the tobacco material to obtain alkalized tobacco material with a pH of 9.5. The alkalized tobacco material is heated in the extraction chamber to a temperature of 140 degrees Celsius for 120 minutes. During heating, a flow of nitrogen is passed through the extraction chamber at a flow rate of approximately 20 liters / minute. The tobacco flow rate is 30 kg per hour, and the extraction chamber is rotated at a speed of 1 rpm to circulate the tobacco. 【0185】 The volatile compounds released from the tobacco material during the heating process were collected by condensation at 0 degrees Celsius and added to a liquid solvent of polypropylene glycol. 【0186】 Nicotine composition 1 shown in the table below is a liquid tobacco extract obtained directly from an extraction process according to the first embodiment of the present invention, wherein an alkali treatment step is performed before heating. 【0187】 In the second comparative extraction method, the tobacco material was extracted under the same conditions as described above, except that the alkali treatment step was omitted. Therefore, the second extraction method is not in accordance with the present invention. Nicotine composition 2 shown in the table below is a liquid tobacco extract obtained directly from this second extraction method. 【0188】 Each nicotine composition was analyzed to measure its nicotine content, and the nicotine yield was calculated based on the total dry weight of the tobacco material. The extraction yield of specific flavor compounds was also measured. The results are shown in the table below. [Table 1] 【0189】 As clearly shown in the table above, when the alkali treatment step is included in the method according to the first embodiment of the present invention, a significant increase in nicotine extraction yield is obtained compared to the method in which the alkali treatment step is omitted. Furthermore, as also shown in the table above, including the alkali treatment step significantly improves the extraction yield of specific pyrazine flavor compounds, namely 2-ethyl-3,5-dimethylpyrazine and 2,3-diethyl-5-methylpyrazine.

Claims

[Claim 1] A method for producing a liquid tobacco extract, wherein the method is The process of preparing tobacco materials, A step of heating the tobacco material at an extraction temperature of 100 degrees Celsius to 160 degrees Celsius for at least 90 minutes. A step of collecting volatile compounds released from the tobacco material during the step of heating the tobacco material, A step of forming a first liquid tobacco extract containing the volatile compounds derived from the collected tobacco material, A step of preparing alkalized tobacco material by adding an alkaline solution to the residual tobacco material remaining after the step of heating the tobacco material, A step of heating the alkalized tobacco material at an extraction temperature of 100 degrees Celsius to 160 degrees Celsius. The process of heating the alkalized tobacco material includes a step of collecting the volatile compounds released from the alkalized tobacco material, and A method comprising the step of forming a second liquid tobacco extract containing volatile compounds derived from the collected alkalized tobacco material. [Claim 2] The method according to claim 1, further comprising the step of combining the first liquid tobacco extract and the second liquid tobacco extract. [Claim 3] The method according to claim 1, further comprising the steps of isolating nicotine from the second liquid tobacco extract and combining at least a portion of the nicotine isolated from the second liquid tobacco extract with the first liquid tobacco extract. [Claim 4] The method according to claim 1, 2, or 3, wherein the tobacco material is heated in a stream of inert gas during at least one of the heating steps. [Claim 5] The method according to any one of claims 1 to 4, wherein the pH of the alkalized tobacco material is at least 8.5, more preferably at least 9.

0. [Claim 6] The method according to any one of claims 1 to 5, wherein the alkaline solution is sprayed onto the tobacco material, and the tobacco material is continuously stirred during the spraying. [Claim 7] The method according to any one of claims 1 to 6, wherein the alkaline solution is an aqueous solution of potassium carbonate. [Claim 8] The method according to any one of claims 1 to 7, wherein the moisture content of the alkalized tobacco material before the heating step is 10% by weight to 20% by weight. [Claim 9] The method according to claim 1, wherein, during the step of heating the alkalized tobacco material, the amount of nicotine extracted from the alkalized tobacco material corresponds to at least 10 grams / kg of dry tobacco material. [Claim 10] The method according to any one of claims 1 to 9, wherein the tobacco material is heated at an extraction temperature of 125 degrees Celsius to 150 degrees Celsius. [Claim 11] The method according to any one of claims 1 to 10, wherein the alkalized tobacco material is heated in an extraction chamber, and the method further comprises the step of spraying atomized water into the extraction chamber during the heating step. [Claim 12] The method according to any one of claims 1 to 11, further comprising the step of drying or concentrating the collected volatile compounds.

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