RU2818243C2 - Method of producing mixed liquid tobacco extract from two or more types of tobacco - Google Patents

Abstract

FIELD: smoking accessories.

SUBSTANCE: invention relates to a method of producing a mixed liquid tobacco extract. Method includes the following steps: preparing a first tobacco starting material characterized by a first reducing sugar content S1 and a first nicotine content N1, preparation of a second tobacco starting material characterized by a second content of S2 reducing sugar and a second content of N2 of nicotine. First tobacco raw material and the second tobacco raw material differ from each other. and wherein the first tobacco starting material and the second tobacco starting material are not pre-extracted. After preparing the materials, the first tobacco source material is heated at a first extraction temperature T1 and the second tobacco source material is heated at a second extraction temperature T2. Second extraction temperature T2 is lower than the first extraction temperature T1. After heating the materials, collecting volatile compounds released from the first and second tobacco raw materials during heating, and combining the collected volatile compounds released from the first and second tobacco starting materials during heating to form a mixed liquid tobacco extract.

EFFECT: invention enables to obtain a compatible composition of a liquid tobacco extract, which is less affected by differences in the type of tobacco in the tobacco starting material, to provide improved control of the composition of the resulting liquid tobacco extract, to maximize the level of desirable flavouring compounds in the obtained liquid tobacco extract with simultaneous minimization of undesirable compounds.

17 cl

Description

The present invention relates to a method for producing liquid tobacco extract from two or more different types of tobacco and to a mixed liquid tobacco extract obtained by this method.

Aerosol generating systems for delivering an aerosol to a user are known that comprise a nebulizer configured to generate a respirable aerosol from a liquid formulation, such as a nicotine-based liquid formulation. Some known aerosol generating systems include a thermal nebulizer, such as an electric heater, configured to heat and vaporize the liquid composition to generate an aerosol. One popular type of electrically heated aerosol generating system is the electronic cigarette. Other known aerosol generating systems comprise a non-thermal atomizer configured to generate an aerosol from a liquid composition using, for example, impingement, ultrasonic or vibrating mesh technologies.

There are several methods for producing liquid tobacco extracts from tobacco material. Liquid tobacco extracts can be produced through 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.

Maceration methods are also known in which the tobacco material, in the form of a suspension, is kept in an extraction liquid for periods of up to several weeks or even months. The resulting pulp is then filtered and the liquid phase thus collected can be used to make a vaporizable liquid composition. In one such method - the so-called "cold maceration method" - there is usually no way to control the extraction conditions (eg temperature and pressure). In one embodiment of the maceration process, which has been described, for example, in US 2012/192880, the pulp is heated to 100 degrees Celsius or higher.

The liquid phase collected from pulp filtration, which is the primary product of the maceration process, is highly dilute and tends to be low in apolar tobacco flavor compounds. Additionally, the liquid phase typically contains little or no nicotine. Thus, liquid extracts produced by the maceration process typically require the addition of additional ingredients, such as nicotine salts and glycerin, before use in a vaporized liquid formulation.

Alternative processes are known in which the tobacco material is essentially boiled in water for several hours or even days to form a vapor phase, and the distillate obtained by condensing the vapor phase is continuously collected in a vessel. Over time, an oily, waxy layer containing a large proportion of apolar compounds accumulates on the surface of the distillate.

On the one hand, the water part, over which the waxy layer accumulates and which contains nicotine and other water-soluble compounds, is returned by recycling to the water heater. The apolar co-solvent may optionally be supplied to the aqueous water heater to increase the yield of the extraction product. On the other hand, the waxy phase is collected and eventually forms the primary product of one such hydrodistillation process. Such a product is often called "tobacco essential oil" and contains a large proportion of apolar compounds found in tobacco, such as fatty acids, neophytadiene, etc. Tobacco essential oil obtained by this method alone generally does not contain nicotine.

It is also known to subject tobacco material to an extraction process involving the use of a volatile apolar solvent. Examples of suitable solvents are cyclic or acyclic short alkanes, as well as 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 very small quantities of the extraction solvent can be detected.

The primary product of one such solvent extraction process is often called "tobacco absolute" and may contain very small amounts of ethanol. It is a waxy product and contains a highly concentrated mixture of most apolar compounds that can be extracted using a specific solvent, usually including nicotine, which is usually present in relatively high concentrations.

An alternative extraction process involves contacting the tobacco material with a solvent under supercritical conditions, such as supercritical carbon dioxide. One such process is disclosed in US 2013/160777 and operates on the principle that volatiles in a feed material that is in contact with a supercritical fluid can be separated into the supercritical phase. After dissolving any soluble material, the supercritical fluid containing the solutes can be removed, and the dissolved components of the feed material can be separated from the supercritical fluid. The primary product of the supercritical extraction process is essentially similar to "tobacco absolute" from the solvent extraction process at lower temperature and lower pressure, contains no residual solvent and typically has a high level of waxy apolar compounds and includes nicotine, which typically present in relatively high concentrations.

However, all tobacco extracts produced by methods known in the art tend to have very low or no levels of compounds associated with the aroma of heated tobacco, such as furaneol. In general, as discussed above, liquid tobacco extracts obtained through such known extraction processes may have low nicotine levels. In addition, liquid tobacco extracts obtained through such extraction processes may have low levels and low diversity of flavor compounds. Liquid tobacco extracts obtained through such extraction processes may also have high levels of undesirable compounds.

In addition, the concentration of nicotine, flavor compounds and undesirable compounds obtained through such extraction processes can be significantly influenced by the type or types of tobacco used as the starting material. Therefore, the composition of the liquid tobacco extract produced by the extraction methods described above may vary significantly among different types of tobacco, resulting in incompatibilities in the extract and the resulting aerosol generated from the extract.

It is therefore desirable to provide an improved extraction process for tobacco that provides improved control over the composition of the resulting liquid tobacco extract. In particular, it is desirable to provide an extraction process that produces a more consistent liquid tobacco extract composition that is less affected by differences in the type of tobacco in the tobacco starting material. It is further desirable to provide an extraction process that can maximize the level of desired flavor compounds in the resulting liquid tobacco extract while minimizing undesirable compounds. It is particularly desirable to provide an extraction process that can be efficiently carried out using existing devices and solutions without the need for significant modification.

The present invention relates to a method for producing a mixed liquid tobacco extract from a first tobacco starting material and a second tobacco starting material. The method may include the step of preparing a first tobacco starting material having a first reducing sugar content S1 and a first nicotine content N1. Additionally, the method may include the step of preparing a second tobacco starting material having a second reducing sugar content S2 and a second nicotine content N2. The method may further include the step of heating the first tobacco starting material at a first extraction temperature T1. Additionally, the method may include the step of heating the second tobacco starting material at a second extraction temperature T2. The second extraction temperature T2 may be lower than the first extraction temperature T1. The method may further include the step of collecting volatile compounds released from the first and second tobacco starting materials during heating. In addition, the method may include the step of combining the collected volatile compounds released from the first and second tobacco raw materials during heating, and forming a mixed liquid tobacco extract from the combined volatile compounds.

According to the present invention, there is provided a method for producing a mixed liquid tobacco extract, the method comprising the steps of: preparing a first tobacco starting material having a first reducing sugar content S1 and a first nicotine content N1; preparing a second tobacco starting material characterized by a second reducing sugar content S2 and a second nicotine content N2; heating the first tobacco starting material at a first extraction temperature T1; heating the second tobacco starting material at a second extraction temperature T2, wherein the second extraction temperature T2 is lower than the first extraction temperature T1; collecting volatile compounds released from the first and second tobacco raw materials during heating; and combining the collected volatile compounds released from the first and second tobacco raw materials during heating, and forming a mixed liquid tobacco extract from the combined volatile compounds.

The present invention also provides a mixed liquid tobacco extract obtained by the above-described method according to the present invention.

As used herein, in relation to the present invention, the term “liquid tobacco extract” describes the direct product of the extraction process carried out on the tobacco starting material. According to the present invention, the extraction process for obtaining liquid tobacco extract includes heating the tobacco starting material under specific heating conditions and collecting the resulting volatile compounds. Therefore, liquid tobacco extract consists of a mixture of natural tobacco components obtained from tobacco source material and removed during the extraction process, usually in combination with a liquid carrier or solvent.

The term "mixed liquid tobacco extract" is used herein to refer to a liquid tobacco extract formed by the process of the present invention by combining and mixing the volatile compounds collected by heating separately two or more different tobacco starting materials, wherein each tobacco starting material is characterized different content of reducing sugar.

The present inventors have discovered that, unlike existing extraction processes that have been discussed above, the methods of the present invention advantageously provide a blended liquid tobacco extract characterized by a significantly higher content of compounds associated with the aroma of heated tobacco, such as, for example, furaneol. These compounds are essentially absent or present in negligible quantities in tobacco extract obtained through the maceration process, which also typically contains little or no nicotine. These compounds are also typically absent or present in trace amounts in solvent-produced tobacco extracts, including those produced under supercritical conditions. Likewise, tobacco essential oil obtained through the distillation process also tends to have very low, if any, levels of such compounds associated with the aroma of heated tobacco.

Blended liquid tobacco extracts produced by the methods of the present invention present significant differences in composition compared to tobacco extracts produced by existing extraction processes and can be used as an e-liquid or to prepare an e-liquid that when heated generates an aerosol that has a different composition and flavor characteristics compared to currently available e-liquids. In particular, mixed liquid tobacco extracts produced by the method of the present invention can be used to generate an aerosol providing a heated tobacco flavor that is more similar to the aerosol generated by traditional cigarettes or by heating tobacco in a heating device without combustion, compared with available aerosols derived from existing nicotine-based liquid formulations.

The extraction methods of the present invention involve selecting different extraction temperatures for the tobacco starting materials. This has been found to advantageously increase the flexibility of the extraction process in that it can provide a wider range of liquid tobacco extracts having different compositions. In particular, by selecting a specific extraction temperature for a given tobacco starting material, the level of certain compounds in the liquid tobacco extract can be controlled. A given tobacco starting material may release different compounds at different temperatures, or these compounds may be present in different proportions in the liquid tobacco extract. Thus, by selecting different extraction temperatures for different tobacco products, the methods of the present invention may also allow more precise control of the ratio between the contents of specific compounds in the liquid tobacco extract.

In preferred embodiments, as will be explained in more detail below, the extraction methods of the present invention involve selecting different extraction temperatures for tobacco starting materials, in particular tobacco starting materials having at least one of different reducing sugar content and different nicotine content relative to each other. . The step of heating the tobacco starting material to release volatile components is carried out separately for each tobacco starting material at a suitable extraction temperature, which can be selected based on reducing sugar content or nicotine content, or both. Therefore, the heating step of the extraction process can be specifically controlled according to the type of tobacco in the tobacco starting material in order to obtain a liquid tobacco extract composition that is optimal for that type of tobacco. The resulting volatile components collected from each of the tobacco starting materials can then be combined in a suitable ratio to produce a blended liquid tobacco extract having the desired composition and flavor properties.

Therefore, the extraction method of the present invention advantageously provides a significantly greater degree of control over the extraction conditions, which in turn provides improved control over the composition of the blended liquid tobacco extract. In particular, by controlling the extraction temperature of different tobacco starting materials according to the reducing sugar content or nicotine content, or both, and then mixing the collected volatile components from each tobacco starting material, the levels of individual desired and undesirable tobacco compounds can be advantageously controlled and optimized. connections.

In the method of the present invention, the specific extraction temperature is selected for each tobacco starting material, preferably based on at least one of the reducing sugar content and the nicotine content of that tobacco starting material, as described in more detail below. When the tobacco starting material is heated, the reducing sugars present in tobacco will produce volatile furan compounds such as 2-furanmethanol, which will be included in the volatile compounds collected during the extraction process. It is generally preferred to minimize the content of furan compounds, such as 2-furanmethanol, in the liquid tobacco extract, since these undesirable compounds are found to be released directly into the aerosol generated when the liquid tobacco extract is heated in the aerosol generating device.

The present inventors have discovered that for certain types of tobacco, the level of 2-furanmethanol released during extraction depends on the extraction temperature. Burley tobacco varieties typically have very low reducing sugar content (less than 2 weight percent) and increasing the extraction temperature has very little effect on the level of 2-furanmethanol released during the extraction process. On the other hand, Bright tobaccos typically have a much higher reducing sugar content (up to 25 wt. percent), and the amount of 2-furanmethanol released by heating has been found to vary significantly with extraction temperature, with a direct correlation between extraction temperature and the level released. 2-furanmethanol. The degree to which the level of 2-furanmethanol released from Bright tobacco increases with increasing extraction temperature may differ for each type of tobacco. The present invention provides a method in which the extraction temperature can be adjusted to account for these differences.

The present inventors have discovered that nicotine is typically present in extracts obtained from Burley tobacco at a higher percentage by weight compared to Bright tobacco. Additionally, the amount of nicotine released by heating depends on the extraction temperature. In more detail, the nicotine content of Bright tobacco extracts is typically relatively low (less than 5 percent by weight), and increasing the extraction temperature has a limited effect on the level of nicotine released during the extraction process. On the other hand, Burley tobacco extracts typically have much higher nicotine content (up to 10 percent by weight), and the amount of nicotine released upon heating is found to vary more significantly with extraction temperature, with a direct correlation between extraction temperature and the level of nicotine released. The present invention provides a method in which the extraction temperature can be adjusted to account for these differences.

In the method of the present invention, selecting an extraction temperature appropriate for each tobacco starting material, which is preferably based on reducing sugar content or nicotine content, can advantageously provide that tobacco starting material with an extract with minimized levels of 2-furanmethanol. Additionally, the extraction temperature can be selected such that, while minimizing the level of 2-furanmethanol, the levels of desired compounds, such as nicotine and flavor compounds, can be maximized. In this way, an improved blended liquid tobacco extract can be obtained having a significantly improved balance of desirable compounds and undesirable compounds.

The method of the present invention allows for a more consistent liquid tobacco extract formulation to be provided regardless of differences in tobacco types with respect to the tobacco starting material. Thus, a greater degree of flexibility can be provided regarding the combination of different types of tobacco, since the extraction from each type of tobacco can be adjusted separately to ensure compatibility of the final blended liquid tobacco extract.

In addition, the extraction method of the present invention produces a natural tobacco extract having desired levels of nicotine and flavor compounds without the need to add these compounds after extraction. Therefore, the resulting mixed liquid tobacco extract can advantageously be used directly to prepare a liquid composition for use in an electronic cigarette or other aerosol generating system.

In many cases, the tobacco starting material can be heated without the need for significant pre-treatment steps. Thus, the extraction method can be carried out efficiently.

The described extraction method can advantageously be carried out using existing devices and technical solutions, which can be easily modified to carry out the steps of the method according to the present invention.

In the method according to the present invention, the first tobacco starting material and the second tobacco starting material are different from each other. According to the present invention, two different tobacco starting materials are provided: a first tobacco starting material characterized by a first reducing sugar content S1 and a first nicotine content N1, and a second tobacco starting material characterized by a second reducing sugar content S2 and a second nicotine content N2.

In some embodiments, S2 is greater than S1. Thus, the reducing sugar content of the second tobacco starting material is greater than the reducing sugar content of the first tobacco starting material. The difference between S2 and S1 will depend on the types of tobacco selected to provide the tobacco starting materials. S2 may be at least about 2 percent larger than S1, or at least about 5 percent larger, or at least about 10 percent larger. S2 may be no more than about 25 percent more than S1, or no more than about 20 percent more than S1, or no more than about 15 percent more than S1.

In these embodiments, the tobacco starting material having a lower S2 reducing sugar content is heated at a lower extraction temperature T2. On the other hand, tobacco raw material, characterized by a high content of reducing sugar S2, is heated at a higher extraction temperature T1. The inventors have surprisingly discovered that this can advantageously increase the ratio between the flavor compound content and the 2-furanmethanol content in the blended liquid tobacco extract.

In other embodiments, N2 is less than N1. Thus, the nicotine content of the second tobacco starting material is less than the nicotine content of the first tobacco starting material. The difference between N1 and N2 will depend on the types of tobacco selected to provide the tobacco starting materials. N2 may be at least about 1 percent less than N1, or at least about 2 percent less, or at least about 5 percent less. N2 may be no more than about 15 percent less than N1, or no more than about 12 percent less than N1, or no more than about 10 percent less than N1. In these embodiments, the tobacco starting material having a higher N1 nicotine content is heated at a higher extraction temperature T1. On the other hand, tobacco starting material having a lower N2 nicotine content is heated at a lower extraction temperature T2.

The inventors have surprisingly discovered that this can advantageously increase the ratio between nicotine content and phenol content in a blended liquid tobacco extract.

Preferably, the first starting material and the second starting material have not been subjected to extraction prior to the implementation of the method according to the present invention.

The extraction temperature is preferably selected for each tobacco starting material based on the reducing sugar content of that tobacco starting material. Typically, in order to reduce the level of 2-furanmethanol released by heating, the higher the reducing sugar content, the lower the extraction temperature will be. For each tobacco starting material, the extraction temperature can be selected to obtain the desired balance between the level of 2-furanmethanol and the level of desired compounds, such as nicotine and flavor compounds.

The first tobacco starting material is heated at a first extraction temperature T1. The second tobacco starting material is heated at a second extraction temperature T2, wherein T2 is lower than T1. T2 is selected to be lower than T1 due to the higher reducing sugar content of the second tobacco starting material compared to the first tobacco starting material.

The extraction temperature can also be selected for each tobacco starting material based on the nicotine content of that tobacco starting material. Typically, in order to maximize the level of nicotine released by heating, the lower the nicotine content, the higher the extraction temperature will be.

Preferably, the first and second extraction temperatures are selected within the range of about 100 degrees Celsius to about 160 degrees Celsius.

The first temperature T1 may be above about 120 degrees Celsius, and the second temperature T2 may be below about 120 degrees Celsius. The first temperature T1 may be above about 130 degrees Celsius, and the second temperature T2 may be below about 130 degrees Celsius. The first temperature T1 may be above about 140 degrees Celsius, and the second temperature T2 may be below about 140 degrees Celsius. The first temperature T1 may be above about 150 degrees Celsius, and the second temperature T2 may be below about 150 degrees Celsius.

The first temperature T1 may be above about 120 degrees Celsius, and the second temperature T2 may be below about 110 degrees Celsius.

The first temperature T1 may be above about 130 degrees Celsius, and the second temperature T2 may be below about 120 degrees Celsius. The first temperature T1 may be above about 130 degrees Celsius, and the second temperature T2 may be below about 110 degrees Celsius.

The first temperature T1 may be above about 140 degrees Celsius, and the second temperature T2 may be below about 130 degrees Celsius. The first temperature T1 may be above about 140 degrees Celsius, and the second temperature T2 may be below about 120 degrees Celsius. The first temperature T1 may be above about 140 degrees Celsius, and the second temperature T2 may be below about 110 degrees Celsius.

The first temperature T1 may be above about 150 degrees Celsius, and the second temperature T2 may be below about 140 degrees Celsius. The first temperature T1 may be above about 150 degrees Celsius, and the second temperature T2 may be below about 130 degrees Celsius. The first temperature T1 may be above about 150 degrees Celsius, and the second temperature T2 may be below about 120 degrees Celsius. The first temperature T1 may be above about 150 degrees Celsius, and the second temperature T2 may be below about 110 degrees Celsius.

Preferably, each 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, more preferably at least about 125 degrees Celsius.

Preferably, each extraction temperature is no more than about 150 degrees Celsius, more preferably no more than about 145 degrees Celsius, more preferably no more than about 140 degrees Celsius, and most preferably no more than about 135 degrees Celsius.

For example, each extraction temperature may be from about 110 degrees Celsius to about 150 degrees Celsius, or from about 120 degrees Celsius to about 140 degrees Celsius, or from about 125 degrees Celsius to about 135 degrees Celsius, or about 130 degrees Celsius. Alternatively, each temperature may be from about 110 degrees Celsius to about 130 degrees Celsius, or from about 115 degrees Celsius to about 125 degrees Celsius, or about 120 degrees Celsius. Alternatively, each temperature may be from about 120 degrees Celsius to about 150 degrees Celsius, more preferably from about 125 degrees Celsius to about 145 degrees Celsius or about 135 degrees Celsius.

The difference (T1-T2) between the first temperature T1 and the second temperature T2 is at least about 1 degree Celsius, preferably at least about 2 degrees Celsius, and even more preferably at least about 5 degrees Celsius.

In preferred embodiments, the difference (T1-T2) between the first temperature T1 and the second temperature T2 is at least about 10 degrees Celsius. More preferably, the difference (T1-T2) between the first temperature T1 and the second temperature T2 is at least about 15 degrees Celsius. Even more preferably, the difference (T1-T2) between the first temperature T1 and the second temperature T2 is at least about 20 degrees Celsius.

In particularly preferred embodiments, the difference (T1-T2) between the first temperature T1 and the second temperature T2 is at least about 25 degrees Celsius, more preferably at least about 30 degrees Celsius, even more preferably at least about 35 degrees Celsius, most preferably at least about 40 degrees Celsius.

Preferably, the difference (T1-T2) between the first and second extraction temperatures is determined based on the difference (S2-S1) between the first and second reducing sugar contents of the first and second tobacco raw materials. This means that, to ensure that the level of 2-furanmethanol in the blended liquid tobacco extract is minimized, the greater the difference (S2-S1) between reducing sugar contents, the greater the difference (T1-T2) between extraction temperatures.

Preferably, the difference between the first and second extraction temperatures (T1-T2) corresponds to at least 0.5 degrees Celsius per 1 percent of the difference between the first and second reducing sugar contents (S2-S1). In other words, if the second reducing sugar content S2 is greater than the first reducing sugar content S1 by x percent, the first extraction temperature T1 will be higher than the second extraction temperature T2 by an amount of 0.5x degrees Celsius. For example, if S2 is 20 weight percent and S1 is 10 weight percent, then, given a difference between S2 and S1 of 10 weight percent, the first extraction temperature T1 is preferably at least 5 degrees higher than the second extraction temperature T2.

More preferably, the difference between the first and second extraction temperatures (T1-T2) corresponds to at least 1 degree Celsius for every 1 percent difference between the first and second reducing sugar contents (S2-S1), more preferably at least 2 degrees Celsius for every 1 percentage of the difference between the first and second contents (S2-S1) of reducing sugar.

Preferably, the difference between the first and second extraction temperatures (T1-T2) corresponds to no more than 10 degrees Celsius for every 1 percent difference between the first and second reducing sugar contents (S2-S1), more preferably no more than 8 degrees Celsius for every 1 percent difference between the first and second contents (S2-S1) of reducing sugar, and more preferably no more than 6 degrees Celsius for every 1 percent difference.

Alternatively or additionally, the percentage difference between the first and second extraction temperatures is preferably at least 0.5 times the percentage difference between the first and second reducing sugar contents (S2-S1). This corresponds to a ratio of at least 0.5 between the percentage difference in the first and second extraction temperatures and the percentage difference between the first and second reducing sugar contents (S2-S1). Since T1 is set as the higher extraction temperature, the percentage difference between T1 and T2 can be calculated by subtracting T2 from T1 (which corresponds to T1-T2) and dividing by T2.

More preferably, the percentage difference between the first and second extraction temperatures is at least about 1 times the percentage difference between the first and second reducing sugar contents (S2-S1), more preferably at least about 2 times the percentage difference between the first and second contents (S2-S1) reducing sugar.

Preferably, the percentage difference between the first and second extraction temperatures is no more than about 6 times the percentage difference between the first and second reducing sugar contents (S2-S1), more preferably no more than about 4 times the percentage difference between the first and second reducing sugar contents (S2-S1). S2-S1) reducing sugar.

The second reducing sugar content S2 may be greater than about 2 weight percent, and the first reducing sugar content S1 may be less than about 2 weight percent. The second reducing sugar content S2 may be greater than about 5 weight percent, and the first reducing sugar content S1 may be less than about 5 weight percent. The second reducing sugar content S2 may be greater than about 10 weight percent, and the first reducing sugar content S1 may be less than about 10 weight percent. The second reducing sugar content S2 may be greater than about 15 weight percent, and the first reducing sugar content S1 may be less than about 15 weight percent. The second reducing sugar content S2 may be greater than about 20 weight percent, and the first reducing sugar content S1 may be less than about 20 weight percent.

The second reducing sugar content S2 may be greater than about 5 weight percent, and the first reducing sugar content S1 may be less than about 2 weight percent.

The second reducing sugar content S2 may be greater than about 10 weight percent, and the first reducing sugar content S1 may be less than about 5 weight percent. The second reducing sugar content S2 may be greater than about 10 weight percent, and the first reducing sugar content S1 may be less than about 2 weight percent.

The second reducing sugar content S2 may be greater than about 15 weight percent, and the first reducing sugar content S1 may be less than about 10 weight percent. The second reducing sugar content S2 may be greater than about 15 weight percent, and the first reducing sugar content S1 may be less than about 5 weight percent. The second reducing sugar content S2 may be greater than about 15 weight percent, and the first reducing sugar content S1 may be less than about 2 weight percent.

The second reducing sugar content S2 may be greater than about 20 weight percent, and the first reducing sugar content S1 may be less than about 15 weight percent. The second reducing sugar content S2 may be greater than about 20 weight percent, and the first reducing sugar content S1 may be less than about 10 weight percent. The second reducing sugar content S2 may be greater than about 20 weight percent, and the first reducing sugar content S1 may be less than about 5 weight percent. The second reducing sugar content S2 may be greater than about 20 weight percent, and the first reducing sugar content S1 may be less than about 2 weight percent.

For example, the nicotine content of Burley tobacco is typically quite high, ranging from about 1.5 weight percent to about 4.5 weight percent. The reducing sugar content of burley tobacco is typically quite low, typically less than about 2 weight percent, and more generally less than about 1 weight percent. Thus, in the methods of the present invention, burley tobacco may be a suitable tobacco starting material for heating to a relatively high extraction temperature.

As a further example, the nicotine content of oriental tobacco is typically quite low, typically ranging from about 0.7 weight percent to about 2.5 weight percent. The reducing sugar content of Oriental tobacco is typically quite high, ranging from about 7 weight percent to about 14 weight percent. Thus, in the methods of the present invention, oriental tobacco may be a suitable tobacco starting material for heating to a relatively low extraction temperature.

As another example, the nicotine content of fire-cured tobacco is typically quite high and comparable to that of Burley tobacco, as it can range from about 1 weight percent to about 4.5 weight percent. The reducing sugar content of fire-cured tobacco is typically high and can vary over a fairly wide range, for example, from about 2.5 weight percent to about 27 weight percent. Thus, in the methods of the present invention, fire-cured tobacco may be a tobacco starting material suitable for heating to a relatively higher or lower extraction temperature depending on which compounds are considered particularly desirable. If the goal is, for example, to maximize the ratio of nicotine content to phenol content, a relatively lower extraction temperature may be preferred. As another example, if the goal is to maximize the ratio of flavor compounds to 2-furanmethanol content, a relatively higher extraction temperature may be preferred.

In some preferred embodiments, the second reducing sugar content is at least 10 percent greater than the first reducing sugar content, and the first extraction temperature is preferably at least about 10 degrees Celsius higher than the second extraction temperature, more preferably at least 20 degrees Celsius higher.

The difference (S2-S1) between the second reducing sugar content S2 and the first reducing sugar content S1 may be at least about 1 weight percent, preferably at least about 2 weight percent, even more preferably at least about 5 weight percent.

In some embodiments, the difference (S2-S1) between the second reducing sugar content S2 and the first reducing sugar content S1 is at least about 10 weight percent, more preferably at least about 12 weight percent, even more preferably at least about 15 weight percent percent.

In other embodiments, the difference (S2-S1) between the second reducing sugar content S2 and the first reducing sugar content S1 is at least about 20 weight percent, more preferably at least about 22 weight percent, even more preferably at least about 25 weight percent percent.

The extraction temperature can also be selected for each tobacco starting material based on the nicotine content of that tobacco starting material. In a preferred embodiment, when the second nicotine content N2 is less than the first nicotine content N1, the difference between the first and second extraction temperatures (T1-T2) corresponds to at least 0.5 degrees Celsius per 1 percent of the difference between the first and second nicotine contents (N1- N2).

The first N1 nicotine content may be greater than about 1 weight percent, and the second N2 nicotine content may be less than about 1 weight percent. The first N1 nicotine content may be greater than about 1.5 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 2 weight percent, and the second N2 nicotine content may be less than about 2 weight percent. The first N1 nicotine content may be greater than about 2.5 weight percent, and the second N2 nicotine content may be less than about 2.5 weight percent. The first N1 nicotine content may be greater than about 3 weight percent, and the second N2 nicotine content may be less than about 3 weight percent. The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 3.5 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 4 weight percent.

The first N1 nicotine content may be greater than about 1.5 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The first N1 nicotine content may be greater than about 2 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 2 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The first N1 nicotine content may be greater than about 2.5 weight percent, and the second N2 nicotine content may be less than about 2 weight percent. The first N1 nicotine content may be greater than about 2.5 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 2 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The first N1 nicotine content may be greater than about 3 weight percent, and the second N2 nicotine content may be less than about 2.5 weight percent. The first N1 nicotine content may be greater than about 3 weight percent, and the second N2 nicotine content may be less than about 2 weight percent. The first N1 nicotine content may be greater than about 3 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 3 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 3 weight percent. The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 2.5 weight percent. The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 2 weight percent. The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 3.5 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 3.5 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 3 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 2.5 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 2 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 1.5 weight percent. The first N1 nicotine content may be greater than about 4 weight percent, and the second N2 nicotine content may be less than about 1 weight percent.

The difference (N1-N2) between the first nicotine content N1 and the second nicotine content N2 may be at least about 0.5 weight percent, preferably at least about 1 weight percent, even more preferably at least about 1.5 weight percent.

In some embodiments, the difference (N1-N2) between the first nicotine content N1 and the second nicotine content N2 is preferably at least about 2 weight percent, more preferably at least about 2.5 weight percent, even more preferably at least about 3 percent by weight, most preferably at least about 3.5 weight percent.

As an example, the first tobacco starting material may have an S1 reducing sugar content of less than about 5 weight percent, or less than about 4 weight percent, or less than about 3 weight percent, or less than about 2 weight percent, or less than about 1 weight percent. The second tobacco starting material may have an S2 reducing sugar content of greater than about 5 weight percent, or greater than about 7 weight percent, or greater than about 9 weight percent, or greater than about 11 weight percent. The first tobacco starting material may have an N1 nicotine content of greater than about 2 weight percent, or greater than about 3 weight percent, or greater than about 4 weight percent. The second tobacco starting material may have an N2 nicotine content of less than about 3 weight percent, or less than about 2 weight percent, or less than about 1 weight percent. The first tobacco starting material can be heated at approximately 130 degrees Celsius. The second tobacco starting material can be heated at approximately 110 degrees Celsius.

Also, in order to provide an additional degree of control over the composition of the extract obtained from each tobacco starting material, the duration of the heating step can optionally be controlled. Preferably, each tobacco starting material is heated at the extraction temperature for at least about 90 minutes, more preferably at least about 120 minutes. This extraction time must be long enough to effectively extract the desired tobacco flavor compounds to provide a liquid tobacco extract capable of forming an aerosol with the desired flavor properties.

Preferably, each 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, each tobacco starting material may be heated for about 90 minutes to about 270 minutes, or about 120 minutes to about 180 minutes. The heating time for the first and second tobacco starting materials may be equal or different.

The above heating time corresponds to the length of time that the tobacco starting material is heated at the corresponding extraction temperature, and does not include the time required to raise the temperature of the tobacco starting material to the extraction temperature.

Preferably, each extraction temperature is selected such that the collected volatile compounds from the respective tobacco starting material contain no more than about 0.8 milligrams of 2-furanmethanol per gram of tobacco starting material, more preferably no more than about 0.6 milligrams of 2-furanmethanol per gram of tobacco starting material .

Preferably, the first and second extraction temperatures are selected such that the blended liquid tobacco extract contains no more than about 1.0 milligrams of 2-furanmethanol per gram of tobacco starting material (based on the combined weight of the first tobacco starting material and the second tobacco starting material), more preferably not more than about 0.8 milligrams of 2-furanmethanol per gram of tobacco starting material.

Preferably, the first and second extraction temperatures are selected to provide a nicotine content of the mixed liquid tobacco extract of at least 0.1 weight percent, more preferably at least about 0.2 weight percent, even more preferably at least about 0. 5 weight percent. Preferably, the first and second extraction temperatures are selected to provide a nicotine content of no more than about 12 weight percent, more preferably no more than about 10 weight percent, even more preferably no more than about 8 weight percent.

In some embodiments, the first and second extraction temperatures are selected to provide a nicotine content of the blended liquid tobacco extract of from about 0.1 weight percent to about 12 weight percent, or from about 0.1 weight percent to about 10 weight percent, or from about 0.1 weight percent to about 8 weight percent. In other embodiments, the first and second extraction temperatures are selected to provide a nicotine content of the blended liquid tobacco extract of from about 0.2 weight percent to about 12 weight percent, or from about 0.2 weight percent to about 10 weight percent, or from about 0.2 weight percent to about 8 weight percent. In additional embodiments, the first and second extraction temperatures are selected to provide a nicotine content of the blended liquid tobacco extract of from about 0.5 weight percent to about 12 weight percent, or from about 0.5 weight percent to about 10 weight percent, or from about 0.5 weight percent to about 8 weight percent.

Preferably, the first and second extraction temperatures are selected to provide a weight ratio of (β-ionone+β-damascenone) to phenol in the liquid tobacco extract of at least about 0.25. More preferably, the first and second extraction temperatures are selected to provide a weight ratio of (β-ionone+β-damascenone) to phenol in the liquid tobacco extract of at least about 0.5, even more preferably at least about 1, most preferably at least at least approximately 1.5. In especially preferred embodiments, the first and second extraction temperatures are selected to provide a weight ratio of (β-ionone+β-damascenone) to phenol in the liquid tobacco extract of at least about 2, and most preferably such that the weight ratio of (β-ionone +β-damascenone) and phenol is from about 2 to about 10 or from about 2 to about 5.

β-damascenone and β-ionone are desirable compounds associated with tobacco aroma. It has been found that the amount of β-damascenone and β-ionone released from tobacco material will increase as the extraction temperature increases until a certain peak extraction temperature, after which this level will begin to decrease. The peak extraction temperature for such flavor compounds is typically in the range of 100 degrees Celsius to 160 degrees Celsius, whereby the level of desired flavor compounds in the extraction process can be effectively adjusted and controlled.

Preferably, the first and second extraction temperatures are selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract of at least about 5 x 10^-4. More preferably, the first and second extraction temperatures are selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract of at least about 8×10^-4. Even more preferably, the first and second extraction temperatures are selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract of at least about 1 x 10^-3. The first and second extraction temperatures are preferably selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract of less than or equal to approximately 9 x 10^-3. More preferably, the first and second extraction temperatures are selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract of less than or equal to about 5 x 10^-3.

In some preferred embodiments, the first and second extraction temperatures are selected to provide a weight ratio of (furaneol + (2,3-diethyl-5-methylpyrazine)*100) to nicotine in the liquid tobacco extract from about 8×10 ^-4 to about 9 ×10 ^-3 or from about 8x10 ^-4 to about 5x10 ^-3 , or from about 1x10 ^-3 to about 9x10 ^-3 , or from about 1x10 ^-3 to about 5x10 ^{- 3} .

It has been found that in the methods of the present invention, where the first and second extraction temperatures are selected to provide ratios within the ranges described above, particularly good sensory profiles can be achieved by heating nicotine-based compositions made from liquid tobacco extracts to generate an aerosol. For a particular tobacco compound, the variation in release level of the compound as a function of extraction temperature in the extraction process for any given tobacco starting material can be readily determined. For example, it has been found that the level of nicotine released from tobacco source material will generally increase as the extraction temperature increases. The magnitude of the increase was found to vary among different types of tobacco.

It has also been found that the level of desirable tobacco flavor compounds such as β-damascenone and β-ionone, which are released from the tobacco material, will increase as the extraction temperature is increased until a certain peak extraction temperature, after which the level will begin to decrease. The peak extraction temperature for such flavor compounds is typically in the range of 100 degrees Celsius to 160 degrees Celsius so that the level of desired flavor compounds can be effectively optimized in the extraction method of the present invention.

Therefore, in the method of the present invention, it is possible to determine the extraction temperature for a particular tobacco starting material, which provides an optimized balance between the level of desired compounds, such as nicotine and certain flavor compounds, and the level of 2-furanmethanol.

As described above, the heating step for each of the first and second tobacco raw materials is carried out separately at a selected extraction temperature.

The heating step for each tobacco starting material is preferably carried out under an inert atmosphere. Preferably, during the heating step, a stream of inert gas, such as nitrogen, is passed through the tobacco starting material. In some cases, a flow of a mixture of inert gas with water or steam can be used. It has been found that adding water or steam to tobacco during extraction increases the yield of extracted components. However, excessive addition of water or steam complicates processing, for example leading to stickiness of the tobacco material.

The volatile compounds of the tobacco are released into the inert gas stream during the heating step, and thus the inert gas (or a mixture of inert gas with water or steam) acts as a carrier for these volatile components. The inert gas flow rate can be optimized based on the scale and geometry of the extraction chamber. A relatively high flow rate of the inert gas can advantageously increase the extraction efficiency from the tobacco starting material.

Typically, when the tobacco starting material is heated, any moisture present in the tobacco starting material is also released along with volatile compounds in the form of steam.

The flow of inert gas facilitates the transfer of vapor generated by the evaporation of moisture contained in the tobacco starting material and volatile compounds, including, but not limited to, nicotine or aroma-related compounds, or both, from the extraction equipment.

In addition, using a flow of an inert gas such as nitrogen at a slight elevated pressure in the extraction equipment has the advantage of preventing oxygen from entering the extraction equipment. This is desirable as it prevents the risk of any, even partial combustion of the tobacco starting material during the heating step. It is clear that uncontrolled combustion of tobacco starting material would be undesirable as it would pose a major safety hazard in an industrial environment. However, the inventors have discovered that even limited, partial combustion of the tobacco starting material can result in a deterioration in the quality of the tobacco extract produced by the process, which would be undesirable.

Without wishing to be bound by any theory, it is understood that by preventing combustion of the tobacco starting material, the formation of any unwanted combustion by-products is also prevented. In addition, since conditions leading to combustion of the tobacco starting material are prevented, the tobacco starting material is effectively heated under conditions that to some extent simulate the conditions under which the tobacco-containing substrate (e.g., homogenized tobacco material) is typically heated in non-combustion heating products " As a result, selective extraction of the aromatic volatile compounds responsible for the taste consumers associate with heated tobacco is advantageously promoted.

Therefore, by carrying out the heating step in an inert atmosphere, extraction efficiency, product quality and process safety are advantageously improved.

Heating the tobacco starting material in an inert gas stream has the additional advantage that the inert gas stream containing volatile compounds can be more easily directed to a container containing an extraction solvent, such as a non-aqueous liquid extraction solvent.

Optionally, the heating step can be carried out in a vacuum. This removes any oxygen present in the extraction chamber, which may advantageously prevent the tobacco starting material from reacting with oxygen or volatile compounds formed when the tobacco starting material is heated. Removing oxygen will also prevent any combustion of the tobacco starting material as described above.

Suitable heating methods for effecting heating of the tobacco starting material are known to those skilled in the art and include, but are not limited to, dry distillation, hydrodistillation, vacuum distillation, equilibrium distillation, and thin film hydrodistillation.

Preferably, each of the first tobacco starting material and the second tobacco starting material contains one type of natural tobacco. This allows extraction temperature and other extraction conditions to be very specifically adjusted to suit the exact type of tobacco. Any mixing of tobacco types is then advantageously carried out at the end of the extraction process using the collected volatile compounds from each of the tobacco starting materials. Alternatively, each of the first tobacco starting material and the second tobacco starting material may comprise a combination of two or more types of natural tobacco.

The first tobacco starting material and the second tobacco starting material may be different types of tobacco or different lines of tobacco.

Preferably, the first tobacco starting material is Burley tobacco and the second tobacco starting material is Bright tobacco. The inclusion of Burley tobacco advantageously provides a relatively high level of nicotine, while the combination with Bright tobacco provides the desired flavor properties of the resulting aerosol generated from the blended liquid tobacco extract.

The term "natural tobacco" is used herein with reference to the present invention to describe any part of any plant belonging to the genus Nicotiana , including, without limitation, leaves, leaf midribs, stems and petioles. In particular, the natural tobacco may include fire-cured tobacco material, burley tobacco material, oriental tobacco material, Maryland tobacco material, dark tobacco material, dark fire-cured tobacco material, shag tobacco material, as well as material from other rare or specialty tobaccos or mixtures of them. As will be described in more detail below, the tobacco material may be whole leaf (eg, whole tobacco leaves), shredded, cut, or ground.

Each of the tobacco starting materials may be solid tobacco material, such as powder, tobacco pharmaceuticals, pieces of tobacco leaves, or intact leaves. Alternatively, each of the tobacco starting materials may be a liquid tobacco material such as a paste, gel, pulp or slurry. The first and second tobacco starting materials may have the same form or different forms.

Each of the tobacco starting materials may be prepared from any suitable tobacco material, including, without limitation, tobacco leaf, tobacco stem, reconstituted tobacco, molded tobacco, extruded tobacco, or tobacco-derived pellets.

Preferably, each of the tobacco starting materials is in the form of a dried and cured tobacco leaf. Before carrying out the method according to the present invention, the tobacco leaf may be cut or shredded.

Preferably, during the preparation step of each of the tobacco starting materials, the tobacco is ground or cut to reduce the size of the tobacco particles in the tobacco starting material. This advantageously improves the heating uniformity of the tobacco starting material and increases the extraction efficiency.

In each case, the tobacco starting material may optionally be dried before the heating step to reduce the water content of the tobacco starting material. Drying of the tobacco starting material can be accomplished by any suitable chemical or physical drying method. Alternatively, water may be added to the tobacco starting material before the heating step to increase the water content of the tobacco starting material.

In some embodiments of the present invention, the step of preparing each of the tobacco starting materials may include the step of impregnating the tobacco starting material with an aerosol-forming substance. When this impregnation of the tobacco starting material is performed prior to the heating step, it can advantageously increase the amount of certain desired tobacco compounds that are released from the tobacco starting material upon heating. For example, it has been found that impregnation of tobacco starting material with glycerin advantageously increases the amount of nicotine extracted from the tobacco starting material. In another example, it has been found that impregnation of the tobacco starting material with a polar aerosol agent, such as a mixture of propylene glycol and vegetable glycerin, or triacetin, advantageously increases the amount of flavor compounds extracted from the tobacco starting material.

Optionally, each of the tobacco starting materials may be fermented prior to the heating step. This has been found to provide significant increases in the yield of certain flavor compounds from tobacco starting material.

Preferably, during the preparation of the tobacco starting materials, the tobacco is not subjected to any treatment to change the pH of the tobacco. In particular, during the preparation of the tobacco raw materials, the tobacco is not subjected to any treatment to significantly increase the pH of the tobacco. For example, tobacco starting materials are not contacted with an aqueous solution containing an alkali or alkaline earth metal salt. Advantageously, it has been found that maintaining the tobacco material in a less modified state can provide a more authentic or more natural flavor profile that can be appreciated by the consumer.

To determine the reducing sugar content of each of the tobacco starting materials, the tobacco starting materials may be analyzed prior to the heating step. This may further provide other information about the composition of the tobacco starting material, such as alkaloid content. This information can help establish optimal extraction conditions. In some cases, the reducing sugar content of a particular type of tobacco may already be established and may form part of the general knowledge of specialists, and then the additional step of analyzing the tobacco source material is not required.

When each of the tobacco starting materials is heated, volatile compounds are released in gaseous form from the tobacco starting material. Volatile compounds are collected using any suitable technique. If the tobacco starting material is heated in an inert gas stream as described above, volatile compounds are collected from the inert gas stream. Various collection methods are well known to those skilled in the art.

In some preferred embodiments, the volatile compounds collection step uses an absorption technique in which the volatile compounds are captured in a liquid solvent. For example, a stream of inert gas containing volatile compounds may be directed into a container containing a liquid solvent. The liquid solvent is preferably an aerosol forming agent such as triacetin, glycerin, propylene glycol, or combinations thereof. The use of the aerosolizing agent as a liquid solvent is potentially beneficial since the aerosolizing agent can be retained as a diluent in the final liquid tobacco extract. This means that the additional solvent removal step is not necessary.

As used herein, in relation to the present invention, the term “aerosol generating agent” refers to a compound or mixture of compounds that, when used, facilitates the formation of an aerosol and is preferably substantially resistant to thermal degradation at the operating temperature of the aerosol generating article or device. Examples of suitable aerosol-forming substances include: polyhydric alcohols such as propylene glycol, triethylene glycol, 1,3-butanediol and glycerin; polyhydric alcohol esters such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Preferably, the liquid solvent is kept at a temperature less than 0 degrees Celsius to optimize the transfer of volatile compounds into the liquid solvent.

In alternative preferred embodiments, the volatile compounds collection step can be accomplished using a condensation technique in which the volatile compounds are condensed and the condensate is collected. Condensation of volatile compounds can be accomplished using any suitable device, for example in a refrigerated column. Preferably, the resulting condensate is added to a liquid substance to form an aerosol, preferably propylene glycol.

The addition of a liquid aerosol agent during the collection step, and in particular the addition of propylene glycol, can advantageously prevent the condensed volatile compounds from separating into two phases or forming an emulsion, as some tobacco constituents tend to do. Without wishing to be bound by any theory, the inventors have discovered that the solubility of tobacco constituents in hydrolate (i.e., the aqueous fraction of a naturally occurring liquid tobacco extract) is primarily dependent on their polarity, concentration, and pH of the hydrolate, which may vary depending on the type. tobacco As a result, if the amount of substance to form an aerosol is insufficient, an oily layer usually forms on the surface of the natural liquid tobacco extract. Such oily material may accumulate in various areas of the recovery and dewatering equipment in which the third and subsequent steps of the process are respectively carried out. The addition of an aerosol former such as propylene glycol helps prevent the formation of such a layer and promotes homogenization of the natural liquid tobacco extract. In turn, this helps prevent any loss of desired aroma-related compounds during the fourth step (dewatering), during which such compounds may be deposited undesirably on equipment surfaces.

In addition, the liquid aerosol forming agent advantageously helps to capture aroma-related compounds regardless of their polarity and volatility. In addition, during any subsequent drying step, the liquid aerosol forming agent helps prevent loss of the most volatile fraction and also assists in selectively removing excess water from the naturally occurring liquid tobacco extract to produce a concentrated tobacco extract.

The use of propylene glycol as a substance for the formation of an aerosol at the collection stage has the additional advantage that due to the reduction of water activity in aqueous solutions, propylene glycol has an antimicrobial effect. Therefore, by adjusting the propylene glycol content of the liquid tobacco extract, it is also possible to ensure that the extract is substantially free of any microbial activity.

As a further alternative, the volatile compound collection step can be carried out using an adsorption technique 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.

In the method of the present invention, the next step is to form a mixed liquid tobacco extract from the volatile compounds collected from each of the tobacco starting materials. For each of the tobacco starting materials, the "collected volatile compounds" will typically comprise a solution of the tobacco-derived volatile compounds in a liquid solvent or carrier.

The collected volatile compounds from each of the tobacco starting materials are combined in the required ratio. This ratio can be adjusted depending on the desired composition and properties of the blended liquid tobacco extract.

Preferably, the step of combining the collected volatile compounds from the first and second tobacco materials includes determining a target range for the content of 2-furanmethanol in the mixed liquid tobacco extract and adjusting the ratio of the collected volatile compounds from the first tobacco material and the second tobacco material to provide a mixed liquid tobacco extract characterized by the content 2-furanmethanol within the target range.

Blended liquid tobacco extract is usually a homogeneous liquid that can be considered an intermediate product or semi-finished product. This intermediate product can be stored for a limited period of permissible storage time (up to approximately 4 weeks) before being subjected to the drying step of the method according to the present invention. The composition of a blended liquid tobacco extract depends on many variables, including the origin of the tobacco starting materials; moisture content of tobacco starting materials; the amount of aerosol-forming agent used to prepare the tobacco starting materials, if present.

When the volatiles are collected by absorption into a liquid solvent as described above, the step of forming the mixed liquid tobacco extract preferably involves drying a solution of the volatiles in the liquid solvent to concentrate the solution. This can be done, for example, to achieve the desired concentration of nicotine or flavor compounds. Drying can be performed before combining the volatile compounds collected from each of the tobacco starting materials, or the collected volatile compounds and the corresponding solvents can be combined and the mixture is dried in one step.

Drying can be accomplished using any suitable means, including, without limitation, dehydration, molecular sieves, freeze drying, phase separation, distillation, membrane permeation, controlled water crystallization and filtration, reverse hygroscopicity, ultracentrifugation, liquid chromatography, reverse osmosis, or chemical drying.

In preferred embodiments, a solution of volatile compounds in a liquid solvent is concentrated by dehydration. 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. To do this, a solution of the volatile compounds in a liquid solvent can be heated to a certain temperature and for a certain time so as to reduce the water content of the tobacco extract by at least about 60 percent.

Partially dehydrated, concentrated tobacco extract can be considered the primary product of the method according to the present invention. The lean tobacco material, from which the volatile compounds and most of the moisture content have been extracted by heating in the second step, can be considered a by-product of the process. Such lean tobacco material may typically have a moisture content of about 1-5 weight percent, preferably about 2-3 weight percent.

In one embodiment, a solution of the volatile compounds 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 volatile compounds in a liquid solvent is heated in a stream of air, preferably in a stream of air having relatively low humidity, at a temperature of at least about 35 degrees Celsius. Thus, a concentrated natural tobacco extract can be obtained using the method of the present invention. One such concentrated natural tobacco extract typically contains less than about 20 weight percent water.

Alternatively, when the volatile compounds are collected by condensation, the step of forming the mixed liquid tobacco extract may include adding condensate from each tobacco starting material to the aerosol forming material.

Optionally, the step of forming the mixed liquid tobacco extract includes a filtering step.

Optionally, the step of forming the mixed liquid tobacco extract includes adding one or more additives, such as an organic acid, to the volatile compound solution. However, in many cases the blended liquid tobacco extract is suitable for use without the inclusion of additives.

The present invention further provides a mixed liquid tobacco extract obtained by the method according to the first aspect of the present invention, as described in more detail above. As described above, the process of the present invention advantageously produces a natural liquid tobacco extract characterized by a highly desirable ratio of desirable tobacco compounds, such as nicotine and flavor compounds, and undesirable tobacco compounds, such as 2-furanmethanol.

The blended liquid tobacco extract is particularly suitable for preparing a nicotine-based composition, such as a liquid nicotine-based composition or a nicotine-based gel composition, for use in an aerosol generating system. In such an aerosol generating system, the nicotine-based composition is typically heated within the aerosol generating device.

As used herein, the term "aerosol generating device" refers to a device containing a heating element that interacts with a nicotine-based composition containing liquid tobacco extract prepared by the method of the present invention to produce an aerosol. During use, volatile compounds are released from the nicotine-based composition by heat transfer and are captured by air drawn through the aerosol generating device. As the released compounds cool, they condense to form an aerosol that is inhaled by the consumer.

When a nicotine-based composition containing a liquid tobacco extract according to the present invention is heated, an aerosol is released that contains volatile compounds collected from the tobacco starting material during the extraction process. The composition and properties of the resulting aerosol produced from the liquid tobacco extract and delivered to the consumer can be controlled by controlling the composition of the liquid tobacco extract using parameter control in the form of an extraction parameter.

A nicotine-based composition for use in an aerosol generating system can be formed directly from the blended liquid tobacco extract without the need for the addition of additional nicotine or flavor compounds. In some embodiments, the nicotine-based composition may be a liquid tobacco extract obtained using the extraction process of the present invention, without the addition of additional nicotine. The nicotine-based composition may be a liquid tobacco extract obtained using the extraction process of the present invention, without the addition of additional nicotine. The nicotine-based composition may be a liquid tobacco extract obtained using the extraction process of the present invention, without the addition of additional flavor compounds. The nicotine-based composition may be a liquid tobacco extract obtained using the extraction process of the present invention, without the addition of additional furaneol. The nicotine-based composition may be a liquid tobacco extract obtained using the extraction process of the present invention, without the addition of additional solvent. For example, the mixed liquid tobacco extract produced by the method of the present invention can be used to make a nicotine composition containing 10 mg to 20 mg of nicotine per milliliter, without the need for added nicotine.

Alternatively, the liquid tobacco extract may be subjected to additional processing steps to form the nicotine-based composition. Even with these additional steps, a nicotine-based composition can be formed without the need to add additional nicotine or flavor compounds.

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-based composition. Preferably, the concentrated tobacco extract contains from 8 weight percent to 15 weight percent water, based on the weight of the concentrated tobacco extract. A nicotine-based composition suitable for use in an aerosol generating system may comprise a mixed liquid tobacco extract produced by the method of the present invention in combination with water and an additional non-aqueous solvent, such as an aerosol generating agent.

The nicotine-based composition may contain at least about 10 weight percent liquid tobacco extract obtained by the method of the present invention. Preferably, the nicotine-based composition contains at least about 20 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains at least about 30 weight percent liquid tobacco extract. In preferred embodiments, the nicotine-based composition contains at least about 40 weight percent liquid tobacco extract, more preferably at least about 50 weight percent liquid tobacco extract, even more preferably at least about 60 weight percent liquid tobacco extract. In especially preferred embodiments, the nicotine-based composition contains at least about 65 weight percent liquid tobacco extract, more preferably at least about 70 weight percent liquid tobacco extract, even more preferably at least about 75 weight percent liquid tobacco extract, most preferably at least about 80 weight percent liquid tobacco extract.

In some embodiments, the liquid tobacco extract is a concentrated tobacco extract. The nicotine-based composition may contain at least about 10 weight percent concentrated tobacco extract, at least about 20 weight percent concentrated tobacco extract, at least about 30 weight percent concentrated tobacco extract, at least about 40 weight percent concentrated tobacco extract, at least about 50 weight percent concentrated tobacco extract, at least about 60 weight percent concentrated tobacco extract, more preferably at least about 70 weight percent concentrated tobacco extract, even more preferably at least about 75 weight percent concentrated tobacco extract and most preferably at least about 80 weight percent concentrated tobacco extract.

In some embodiments, the nicotine-based composition contains from about 40 weight percent to about 95 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 40 weight percent to about 95 weight percent liquid tobacco extract. Even more preferably, the nicotine-based composition contains from about 50 weight percent to about 95 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 60 weight percent to about 95 weight percent liquid tobacco extract. In some particularly preferred embodiments, the nicotine-based composition contains from about 70 weight percent to about 95 weight percent liquid tobacco extract, even more preferably from about 80 weight percent to about 95 weight percent liquid tobacco extract.

In some embodiments, the nicotine-based composition contains from about 40 weight percent to about 90 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 40 weight percent to about 90 weight percent liquid tobacco extract. Even more preferably, the nicotine-based composition contains from about 50 weight percent to about 90 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 60 weight percent to about 90 weight percent liquid tobacco extract. In some particularly preferred embodiments, the nicotine-based composition contains from about 70 weight percent to about 90 weight percent liquid tobacco extract, even more preferably from about 80 weight percent to about 90 weight percent liquid tobacco extract.

In some embodiments, the nicotine-based composition contains from about 40 weight percent to about 85 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 40 weight percent to about 85 weight percent liquid tobacco extract. Even more preferably, the nicotine-based composition contains from about 85 weight percent to about 90 weight percent liquid tobacco extract. More preferably, the nicotine-based composition contains from about 60 weight percent to about 85 weight percent liquid tobacco extract. In some particularly preferred embodiments, the nicotine-based composition contains from about 70 weight percent to about 85 weight percent liquid tobacco extract, even more preferably from about 80 weight percent to about 85 weight percent liquid tobacco extract.

The nicotine-based composition may contain up to about 100 weight percent liquid tobacco extract. In some embodiments, the nicotine-based composition may be formed directly from the liquid tobacco extract without the need for the addition of additional non-aqueous solvent, flavorings, or nicotine. That is, the nicotine-based composition may contain 100 weight percent liquid tobacco extract. In some embodiments, the liquid tobacco extract is a concentrated tobacco extract, in which case the nicotine-based composition may contain 100 weight percent concentrated tobacco extract. In embodiments in which the nicotine-based composition contains 100 weight percent liquid tobacco extract or 100 weight percent concentrated tobacco extract, no additional non-aqueous solvent is present.

Alternatively, in some embodiments, the nicotine-based composition containing liquid tobacco extract may contain an additional non-aqueous solvent. The additional non-aqueous solvent is the non-aqueous solvent that was added after the extraction step. The additional non-aqueous solvent is a solvent that is auxiliary to the non-aqueous extraction solvent present in the liquid tobacco extract. In embodiments in which the liquid tobacco extract is a concentrated tobacco extract, the nicotine-based composition containing the concentrated tobacco extract may contain an additional non-aqueous solvent.

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

In embodiments in which the nicotine-based composition contains an additional non-aqueous solvent, the nicotine-based composition may contain 90 weight percent or less of the additional non-aqueous solvent. Preferably, the nicotine-based composition contains 80 weight percent or less of additional non-aqueous solvent. More preferably, the nicotine-based composition contains 70 weight percent or less of additional non-aqueous solvent. In preferred embodiments, the nicotine-based composition contains about 60 weight percent or less of additional non-aqueous solvent, about 50 weight percent or less of additional non-aqueous solvent, even more preferably about 40 weight percent or less of additional non-aqueous solvent. In some particularly preferred embodiments, the nicotine-based composition contains about 35 weight percent or less of additional non-aqueous solvent, more preferably about 30 weight percent or less of additional non-aqueous solvent, even more preferably about 25 weight percent or less of additional non-aqueous solvent, most preferably about 20 percent by weight or less of liquid tobacco extract.

In the nicotine-based composition obtained by the method of the present invention, at least 50 weight percent, based on the total weight of the nicotine-based composition, of the nicotine content of the nicotine-based composition may come from the tobacco extract rather than being added after extraction. In preferred embodiments, at least 80 weight percent, based on the total weight of the nicotine-based composition, of the nicotine content of the nicotine-based composition comes from the tobacco extract rather than being added after extraction. Even more preferably, at least 90 weight percent, based on the total weight of the nicotine-based composition, of the nicotine content of the nicotine-based composition comes from the tobacco extract rather than being added after extraction.

In the nicotine-based composition obtained by the method of the present invention, at least 50 weight percent, based on the total weight of the nicotine-based composition, of the non-aqueous extraction solvent content of the nicotine-based composition may come from tobacco extract rather than being added after extraction. In preferred embodiments, at least 80 weight percent, based on the total weight of the nicotine composition, of the non-aqueous extraction solvent content of the nicotine composition comes from the tobacco extract rather than being added after extraction. Even more preferably, at least 90 weight percent, based on the total weight of the nicotine-based composition, of the non-aqueous extraction solvent content of the nicotine-based composition comes from the tobacco extract rather than being added after extraction.

In the nicotine-based composition obtained by the method of the present invention, at least 50 weight percent, based on the total weight of the nicotine-based composition, of the water content of the nicotine-based composition may come from the tobacco extract rather than being added after extraction. In preferred embodiments, at least 80 weight percent, based on the total weight of the nicotine-based composition, of the water content of the nicotine-based composition comes from the tobacco extract rather than being added after extraction. Even more preferably, at least 90 weight percent, based on the total weight of the nicotine-based composition, of the water content of the nicotine-based composition comes from the tobacco extract rather than being added after extraction.

In a nicotine composition prepared by the method of the present invention, at least 50 weight percent, based on the total weight of the nicotine composition, of the desired tobacco flavor compounds in the nicotine composition may be derived from the tobacco extract rather than added after extraction. . In preferred embodiments, at least 80 weight percent, based on the total weight of the nicotine-based composition, of the desired tobacco flavor compounds in the nicotine-based composition comes from the tobacco extract rather than being added after extraction. Even more preferably, at least 90 weight percent, based on the total weight of the nicotine-based composition, of the desired tobacco flavor compounds in the nicotine-based composition comes from the tobacco extract rather than being added after extraction.

The nicotine-based composition may have a total propylene glycol content of from about 10 weight percent to about 95 weight percent. The nicotine-based composition may have a total propylene glycol content of from about 20 weight percent to about 95 weight percent, such as from about 50 weight percent to about 95 weight percent, or from about 65 weight percent to about 95 weight percent, from about 70 weight percent to about 90 weight percent, or about 80 weight percent to about 90 weight percent.

The nicotine-based composition may have a total triacetin content of from about 10 weight percent to about 95 weight percent. The nicotine composition may have a total triacetin content of from about 20 weight percent to about 95 weight percent, such as from about 50 weight percent to about 95 weight percent, from about 70 weight percent to about 90 weight percent, or from about 65 weight percent to about 95 weight percent, or about 80 weight percent to about 90 weight percent.

The nicotine-based composition may have a total glycerol content of from about 10 weight percent to about 95 weight percent. The nicotine-based composition may have a total glycerol content of from about 20 weight percent to about 95 weight percent, such as from about 50 weight percent to about 95 weight percent, or from about 65 weight percent to about 95 weight percent, from about 70 weight percent to about 90 weight percent, or about 80 weight percent to about 90 weight percent.

The nicotine-based composition may have a total 1,3-propanediol content of from about 10 weight percent to about 95 weight percent. The nicotine-based composition may have a total 1,3-propanediol content of from about 20 weight percent to about 95 weight percent, such as from about 50 weight percent to about 95 weight percent, or from about 65 weight percent to about 95 weight percent, or from about 80 weight percent to about 90 weight percent.

The nicotine composition of the present invention contains at least 0.2 weight percent nicotine. More preferably, the nicotine content of the liquid tobacco extract of the nicotine-based composition is at least about 0.4 weight percent. The nicotine composition may have a nicotine content of about 12 weight percent or less, such as about 10 weight percent or less, preferably about 8 weight percent or less, more preferably about 5 weight percent or less, preferably about 3.6 weight percent or less . More preferably, the nicotine-based composition contains from about 0.4 weight percent to 3.6 weight percent nicotine, based on the weight of the nicotine-based composition.

The nicotine-based composition may contain from 1 weight percent to 85 weight percent water. The nicotine-based composition may contain from 2 weight percent to 50 weight percent water. The nicotine-based composition may contain from 3 weight percent to 30 weight percent water. The nicotine-based composition may contain from 5 weight percent to 25 weight percent water. The nicotine-based composition may contain from 8 weight percent to 20 weight percent water. The nicotine-based composition preferably contains from 10 weight percent to 15 weight percent water.

In some embodiments, the nicotine-based 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” describes an organic acid having a solubility in water at 20° C. that is greater than or equal to about 500 mg/ml.

One or more water-soluble organic acids may advantageously bind nicotine in the liquid tobacco extract by forming one of the nicotine salts. One or more nicotine salts may advantageously be dissolved and stabilized in the water present in the liquid tobacco extract or non-aqueous solvent. This may advantageously reduce nicotine absorption in the upper respiratory tract and improve nicotine delivery and retention into the lungs, as discussed above.

Preferably, the nicotine-based composition has a water-soluble organic acid content that is greater than or equal to about 2 weight percent. More preferably, the nicotine-based composition has a water-soluble organic acid content that is greater than or equal to about 3 weight percent.

The water-soluble organic acid may be acetic acid.

Exogenous acetic acid is acetic acid that has been added from a source other than tobacco plant material and is not the acetic acid naturally present in the tobacco plant that has been isolated, extracted, or obtained from tobacco plant material using extraction conditions and techniques processing.

If acetic acid is added to the liquid tobacco extract to form a nicotine composition, the total acetic acid content of the nicotine composition, including both exogenous and endogenous acetic acid, is preferably from about 0.01 weight percent to about 8 weight percent for example, from about 0.03 weight percent to about 8 weight percent, from about 0.3 weight percent to about 8 weight percent, from about 2 weight percent to about 8 weight percent, or from about 3 weight percent to about 8 weight percent . More preferably, the total acetic acid content is from about 0.01 weight percent to about 6 weight percent, for example, from about 0.03 weight percent to about 6 weight percent, from about 0.3 weight percent to about 6 weight percent, from about 2 weight percent to about 6 weight percent or from about 3 weight percent to about 6 weight percent.

Preferably, the nicotine-based composition has a water-soluble organic acid content that is less than or equal to about 8 weight percent. More preferably, the nicotine-based composition has a water-soluble organic acid content that is less than or equal to about 6 weight percent.

Preferably, the nicotine-based composition has a water-soluble organic acid content of from about 2 weight percent to about 8 weight percent. For example, a nicotine-based composition may have a water-soluble organic acid content ranging from about 2 weight percent to about 6 weight percent.

More preferably, the nicotine-based composition has a water-soluble organic acid content of from about 3 weight percent to about 8 weight percent. For example, a nicotine-based composition may have a water-soluble organic acid content ranging from about 3 weight percent to about 6 weight percent.

The nicotine-based composition may contain one or more non-tobacco flavoring agents. Suitable non-tobacco flavorings include, but are not limited to, menthol.

Preferably, the nicotine-based composition has a non-tobacco flavoring content that is less than or equal to about 4 weight percent. More preferably, the nicotine-based composition has a non-tobacco flavoring content that is less than or equal to about 3 weight percent.

The nicotine-based composition containing the mixed liquid tobacco extract of the present invention may be provided in a cartridge for use in an aerosol generating system. The cartridge may include an atomizer configured to generate an aerosol from the nicotine-based composition. The atomizer may be a thermal atomizer configured to heat the nicotine-based composition to generate an aerosol. The thermal atomizer may include, for example, a heater and a liquid moving element configured to move the nicotine-based composition toward the heater. The fluid transfer element may include a capillary wick. Alternatively, the atomizer may be a non-thermal atomizer configured to generate an aerosol from the nicotine-based composition in a manner other than heating. The non-thermal nebulizer may be, for example, a falling jet nebulizer, an ultrasonic nebulizer, or a vibrating mesh nebulizer.

A cartridge containing a nicotine-based composition formed from a liquid tobacco extract according to the present invention can be used in combination with any suitable aerosol generating device that includes a housing configured to receive at least a portion of the cartridge. The aerosol generating device may include a battery and an electronic control circuit.

One embodiment of the present invention will now be described by way of example only.

Example

The first tobacco starting material is prepared from burley tobacco material having a reducing sugar content of less than 2 weight percent. The second tobacco starting material is prepared from fire-cured Bright tobacco material having a reducing sugar content of approximately 12 weight percent. For each of the tobacco starting materials, the tobacco material is cut to form tobacco pieces having dimensions of 2.5 millimeters by 2.5 millimeters, and these tobacco pieces are loaded into the extraction chamber without compression. The tobacco starting material is heated in an extraction chamber. During heating, a stream of nitrogen is passed through the extraction chamber at a flow rate of approximately 40 liters per minute.

The first tobacco starting material is heated at a temperature of 140 degrees Celsius for 120 minutes. The second tobacco starting material is heated at 130 degrees Celsius for 180 minutes.

For each tobacco starting material, volatile compounds released during the heating step are collected by absorption into a liquid solvent formed from propylene glycol at minus 10 degrees Celsius and stirring at 750 rpm. The propylene glycol solution with the collected volatile compounds is dried in a dewatering process to reduce the moisture content of the solution to approximately 15 percent.

The volatiles collected from the first tobacco starting material contain less than 0.05 mg of 2-furanmethanol per gram of tobacco. The volatiles collected from the second tobacco starting material contained approximately 0.65 mg of 2-furanmethanol per gram of tobacco.

The resulting concentrated solutions of the collected volatiles from the first and second tobacco raw materials are mixed in a ratio of approximately 60:40 to produce a blended liquid tobacco extract.

The blended liquid tobacco extract provides optimized levels of nicotine and desirable flavor compounds such as β-damascenone and β-ionone, while maintaining relatively low levels of 2-furanmethanol.

Claims (23)

1. A method for producing a mixed liquid tobacco extract, including the steps: preparing a first tobacco starting material characterized by a first reducing sugar content S1 and a first nicotine content N1; preparing a second tobacco starting material characterized by a second reducing sugar content S2 and a second nicotine content N2, wherein the first tobacco starting material and the second tobacco starting material are different from each other, and wherein the first tobacco starting material and the second tobacco starting material are not pre-extracted; heating the first tobacco starting material at a first extraction temperature T1; heating the second tobacco starting material at a second extraction temperature T2, wherein the second extraction temperature T2 is lower than the first extraction temperature T1; collecting volatile compounds released from the first and second tobacco raw materials during heating; And combining the collected volatile compounds released from the first and second tobacco raw materials during heating, and forming a mixed liquid tobacco extract from the combined volatile compounds. 2. The method according to claim 1, wherein the first and second extraction temperatures are selected within the range of 100 to 160 degrees Celsius. 3. The method according to claim 1 or 2, in which the difference between the first and second extraction temperatures (T1-T2) is at least 10 degrees Celsius. 4. Method according to any one of paragraphs. 1-3, in which the second reducing sugar content S2 is greater than the first reducing sugar content S1. 5. The method according to claim 4, wherein the difference between the first and second extraction temperatures (T1-T2) corresponds to at least 1 degree Celsius per 1 percent of the difference between the first and second reducing sugar contents (S2-S1). 6. The method according to claim 4, wherein the percentage difference between the first and second extraction temperatures is at least 0.5 times greater than the percentage difference between the first and second reducing sugar contents. 7. Method according to any one of paragraphs. 4-6, wherein the second reducing sugar content is at least 10 percent greater than the first reducing sugar content, and wherein the first extraction temperature is at least 10 degrees Celsius higher than the second extraction temperature. 8. Method according to any one of paragraphs. 1-3, wherein the second nicotine content N2 is less than the first nicotine content N1. 9. The method according to claim 8, wherein the difference between the first and second extraction temperatures (T1-T2) corresponds to at least 0.5 degrees Celsius per 1 percent of the difference between the first and second nicotine contents (N1-N2). 10. The method of any one of the preceding claims, wherein each extraction temperature is selected such that the collected volatile compounds from the respective tobacco starting material contain no more than 0.8 milligrams of 2-furanmethanol per gram of tobacco starting material. 11. The method of any one of the preceding claims, wherein the first and second extraction temperatures are selected to provide a liquid tobacco extract having a nicotine content of at least 0.02 weight percent, based on the dry weight of the liquid tobacco extract. 12. The method of any one of the preceding claims, wherein the first and second extraction temperatures are selected to provide a weight ratio of (β-ionone+β-damascenone) to phenol of at least about 0.25. 13. The method as claimed in any one of the preceding claims, wherein the first and second extraction temperatures are selected to provide a weight ratio of (furaneol+(2,3-diethyl-5-methylpyrazine)*100) to nicotine of at least about 5×10 ^{- 4} . 14. The method of any one of the preceding claims, wherein the first tobacco starting material is Burley tobacco and the second tobacco starting material is Bright tobacco. 15. The method of any one of the preceding claims, wherein the step of combining the collected volatile compounds from the first and second tobacco materials includes determining a target range for the content of 2-furanmethanol in the liquid tobacco extract and adjusting the ratio of the collected volatile compounds from the first tobacco material and the second tobacco material with the purpose of providing a blended liquid tobacco extract having a 2-furanmethanol content within the target range of no more than 1.0 milligrams of 2-furanmethanol per gram of tobacco starting material. 16. The method of any one of the preceding claims, wherein each of the first and second tobacco raw materials is heated at a corresponding extraction temperature for at least 90 minutes. 17. The method as claimed in any one of the preceding claims, wherein each of the first and second tobacco raw materials is heated under a stream of inert gas.