RU2845700C1 - Aerosol-generating product, an aerosol-generating system, and a method for producing homogenized tobacco material - Google Patents

Abstract

FIELD: smoking accessories.

SUBSTANCE: invention relates to an aerosol-generating article. Disclosed article comprises an aerosol-generating substrate rod, wherein the aerosol-generating substrate comprises a homogenised tobacco material which contains from 10 to 50 percent by weight of dried green tobacco material in terms of dry weight, aged tobacco material or an aerosol-generating plant material, an aerosol-forming agent and an exogenous binder. Homogenised tobacco material contains an aerosol-forming substance equal to 5-55 wt. % in terms of dry weight.

EFFECT: invention enables to obtain an aerosol-generating article in which the resultant aerosol has no unpleasant odours or tastes.

15 cl, 7 dwg, 4 tbl, 1 ex

Description

The present invention relates to a new aerosol-generating substrate containing dried green tobacco material and to an aerosol-generating article containing such a substrate. The present invention further relates to methods for producing dried green tobacco material for an aerosol-generating substrate.

In the production of combustible tobacco products, it is considered important to use only tobacco material that has been sufficiently aged, as it has been found that the use of unaged green tobacco leaves creates undesirable aromas and flavors when the tobacco leaves are burned during smoking. By aging the tobacco material through a drying process and turning it brown, it is possible to change the chemical composition of the tobacco in such a way as to minimize undesirable aromas and flavors. The tobacco industry uses various aging methods, including, but not limited to, flue-cured aging, air-cured aging, and sun-cured aging.

Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-containing substrate, is heated rather than burned are known in the art. Typically, in such articles, an aerosol is generated by heat transfer from a heat source to a physically separate aerosol-generating substrate or material, which may be located in contact with, within, around, or downstream of the heat source. During use of the aerosol-generating article, volatile compounds are released from the substrate by heat transfer from the heat source and are entrained in air drawn through the article. As the released compounds cool, they condense to form an aerosol.

In the production of tobacco-containing aerosol-generating substrates for such heated aerosol-generating articles, aged tobacco material is used to create an aerosol that reproduces the aromas and flavors of smoke from a combustible smoking article.

The process of aging tobacco begins with the collection of unaged green tobacco leaves, followed by a "simmering" stage that lasts on average 5 to 10 days, and finally a drying or browning stage that can last up to 50 days. As the tobacco leaves age, they change from their original green color first to yellow and then to brown as the chlorophyll in the leaves breaks down. At each stage, aging continues until the desired moisture level in the tobacco leaves is reached. In unaged green tobacco leaves, the green color is a result of the high chlorophyll content in the leaves. In contrast, after aging, the tobacco leaves are found to contain only very low levels of chlorophyll and are brown in color.

The curing processes used in the tobacco industry are relatively labor-intensive and often require significant space and resources. Attempts have been made to use alternative, faster, processes to dry tobacco material without curing it. However, the resulting cured tobacco material has not been found suitable for use in combustible smoking articles because the rapid drying processes do not remove or significantly reduce the levels of components that create undesirable aromas and flavors when the tobacco burns.

It would be desirable to create a new aerosol-generating substrate for a heated aerosol-generating article that could be produced in a more efficient manner but without adversely affecting the organoleptic properties of the resulting aerosol generated by heating the substrate.

The present invention relates to an aerosol-generating substrate for an aerosol-generating article. The aerosol-generating substrate may comprise dried green tobacco material, an aerosol-forming substance, and a binder.

The present invention also relates to an aerosol-generating article comprising a rod of aerosol-generating substrate.

The present invention also relates to the use of dried green tobacco leaves in the production of an aerosol-generating substrate for an aerosol-generating article.

The present invention also relates to a dried green tobacco material having a moisture content of between about 4 percent by weight and about 15 percent by weight and a chlorophyll level of at least 0.5 milligrams per gram.

According to the present invention, an aerosol-generating substrate for a heated aerosol-generating article is provided, comprising dried green tobacco material, an aerosol-forming substance and a binder. The aerosol-generating substrate may be present in the form of a homogenized tobacco material containing between 5 percent by weight and 55 percent by weight of an aerosol-forming substance.

According to the present invention, an aerosol-generating article is further provided, comprising a rod of an aerosol-generating substrate, wherein the aerosol-generating substrate comprises dried green tobacco material, an aerosol-forming substance and a binder. The aerosol-generating substrate may be present in the form of a homogenized tobacco material containing between 5 percent by weight and 55 percent by weight of an aerosol-forming substance.

According to the present invention, it is further proposed to use dried green tobacco material in the production of an aerosol-generating substrate for an aerosol-generating article, wherein the aerosol-generating substrate comprises dried green tobacco material, an aerosol-forming substance and a binder.

According to the present invention, there is further provided a dried green tobacco material having a moisture content of between about 4 percent by weight and about 15 percent by weight and a chlorophyll level of at least 0.5 milligrams per gram.

The present disclosure further relates to a method for producing dried green tobacco material for use in an aerosol-generating substrate as defined above. The method may include: providing unaged green tobacco leaves; drying the unaged green tobacco leaves until a moisture content of between 4 percent by weight and 15 percent by weight is achieved; and cutting or grinding the unaged green tobacco leaves to obtain dried green tobacco material. The temperature, pressure and duration of the drying step may be selected such that the dried green tobacco material retains a chlorophyll level of at least 0.5 milligrams per gram.

According to the present invention, there is provided a method for producing dried green tobacco material for use in an aerosol-generating substrate according to the present invention, as defined above. The method comprises: providing unaged green tobacco leaves; drying the unaged green tobacco leaves until a moisture content of between 4 percent by weight and 15 percent by weight is achieved; and cutting or grinding the unaged green tobacco leaves to obtain dried green tobacco material. According to the present invention, the temperature, pressure and duration of the drying step are preferably selected such that the dried green tobacco material retains a chlorophyll level of at least 0.5 milligrams per gram. Preferably, the drying step is performed by heating the unaged green tobacco leaves to a temperature of between 75 degrees Celsius and 120 degrees Celsius for no more than 4 hours.

According to the present invention, there is further provided a dried green tobacco material obtained by the method according to the present invention, as defined above.

According to the present invention, there is further provided a method for producing a homogenized tobacco material for use in an aerosol-generating substrate according to the present invention, as defined above. The method includes the following steps: mixing dried green tobacco material, an aerosol-forming agent, a binder and water to form a pulp; casting the pulp onto a surface to form a sheet of homogenized tobacco material; and drying the sheet of homogenized tobacco material, wherein the sheet of homogenized tobacco material has an aerosol-forming agent content of between 5 percent by weight and 55 percent by weight, based on dry weight.

Any references below to aerosol-generating substrates and aerosol-generating articles of the present invention should be construed as applicable to all aspects of the present invention.

As used herein, the term "aerosol-generating article" refers to an article for creating an aerosol that contains an aerosol-generating substrate that is suitable and designed to be heated or combusted to release volatile compounds that can form an aerosol. A conventional cigarette is lit when a user applies a flame to one end of the cigarette and draws air through the other end. The localized heat provided by the flame and the oxygen in the air drawn through the cigarette causes the end of the cigarette to ignite, and the resulting combustion results in the generation of inhalable smoke. In contrast, in "heated aerosol-generating articles," the aerosol is generated by heating the aerosol-generating substrate rather than by combusting the aerosol-generating substrate. Known heated aerosol-generating articles include, for example, electrically heated aerosol-generating articles and aerosol-generating articles in which the aerosol is generated by heat transfer from a combustible heat-generating element or heat source to a physically separate aerosol-generating substrate.

Also known are aerosol-generating articles that are capable of being used in an aerosol-generating system that supplies an aerosol-forming substance to the aerosol-generating articles. In such a system, the aerosol-generating substrate in the aerosol-generating articles contains substantially less aerosol-forming substance than an aerosol-generating substrate that contains and provides essentially all of the aerosol-forming substance used to create the aerosol during use.

As used herein, the term "aerosol-generating substrate" refers to a substrate that is capable of generating volatile compounds upon heating that can form an aerosol. The aerosol generated from aerosol-generating substrates may be visible or invisible to the human eye, and may contain vapors (e.g., finely dispersed particles of substances that are in a gaseous state and are typically liquid or solid at room temperature), as well as gases and liquid droplets of condensed vapors.

The aerosol generating substrate according to the present invention is particularly suitable for use in heated aerosol generating articles, also known as heated without combustion articles.

The aerosol-generating substrate according to the present invention may be present in any suitable form that is capable of generating an aerosol upon heating. Preferably, the aerosol-generating substrate is present in the form of a homogenized tobacco material, such as a cast sheet, tobacco paper or reconstituted tobacco material. Alternatively, the aerosol-generating substrate may be present in the form of a loose tobacco material, such as cut tobacco filler.

As used herein, the term "homogenized tobacco material" includes any plant material obtained by agglomerating particles of tobacco plant. For example, sheets or webs of homogenized tobacco material for aerosol-generating substrates according to the present invention can be obtained by agglomerating particles of plant material obtained by grinding, milling or shredding tobacco plant material, such as tobacco leaf blades or tobacco leaf stalks.

The homogenized tobacco material may be obtained by molding, extrusion, papermaking or any other suitable processes known in the art.

The term "cured green tobacco material" is used in this specification to denote a material obtained from tobacco leaves that have been dried without undergoing any aging process. Accordingly, the cured green tobacco material is unaged. Such cured green tobacco material will generally retain its natural green color. The cured green tobacco material is obtained from unaged green tobacco leaves that are dried as described below to provide the required moisture content, but without any aging. The cured green tobacco material can be obtained from tobacco lamina, tobacco stalks, or a combination of both. The cured green tobacco material preferably has a moisture content of less than 15 percent by weight.

The term "unaged green tobacco leaves" is used in this description to refer to tobacco leaves that have not been subjected to any aging process after harvesting.

Thus, the present invention provides a new aerosol generating substrate obtained from at least a proportion of dried green tobacco material, which will typically be provided in a mixture with a proportion of aged tobacco material.

The inventors of the present invention have unexpectedly found that an aerosol-generating substrate for a heated aerosol-generating article can be produced using at least a proportion of dried green tobacco material instead of aged tobacco material, without adversely affecting the organoleptic properties of the resulting aerosol. In particular, it has unexpectedly been found that when a substrate containing dried green tobacco material is heated, rather than burned, to form an aerosol, the resulting aerosol does not have the unpleasant odours or tastes that are generated when using green tobacco material in a combustible smoking article, as described above.

Dried green tobacco material provides the advantage of being able to be produced much more quickly and efficiently than aged tobacco material, as a rapid drying process can be used to achieve the required moisture content rather than a much slower aging process. Dried green tobacco material can also be produced naturally and organically, which provides a more sustainable process for producing aerosol-generating substrates.

Advantageously, the methods for drying unaged green tobacco leaves to produce dried green tobacco material suitable for use in the aerosol-generating substrate of the present invention can be applied to all types of tobaccos.

In addition, it has been found that unaged green tobacco leaves can be dried and processed without removing the stalks, which further improves the efficiency of producing the aerosol-generating substrate according to the present invention.

It is known that the aging process of tobacco affects the chemical composition of the tobacco and, in particular, the levels of certain tobacco components that affect the taste/aroma of the resulting aerosol generated from the aerosol-generating substrate and the levels of certain undesirable tobacco components. For example, it has been unexpectedly found that by eliminating the aging step in producing dried green tobacco material, there are significantly reduced levels of asparagine, ammonia, free amino acids and total alkaloids compared to aged tobacco. This has the effect that the aerosol obtained from the aerosol-generating substrate according to the present invention will include less undesirable compounds such as acrylamide, hydrogen sulfide ( _H2S ) and methanethiol (MeSH). Thus, the inclusion of dried green tobacco material in an aerosol-generating substrate provides for the generation of an improved aerosol upon heating of the substrate compared to the aerosol generated from a substrate with only aged tobacco and without dried green tobacco material.

It has also been found that the dried green tobacco material has a significantly higher sugar level than the aged tobacco material. The presence of sugars in the dried green tobacco material provides an advantage in that it can assist in the production of an aerosol-generating substrate, for example, when the aerosol-generating substrate is produced using a sheet casting process as described below. In particular, the relatively high sugar level in the dried green tobacco material increases the flexibility of the sheet of aerosol-generating substrate produced from the dried green tobacco material.

As described above, when tobacco material is not subjected to the aging process, it typically retains its natural high level of chlorophyll and, therefore, its green color. A direct result of including a proportion of dried green tobacco material in the aerosol-generating substrate of the present invention is that the chlorophyll level in such substrate is significantly higher than the level that would be measured in a typical substrate obtained from aged tobacco alone. Aged tobacco always has a brown color and a low, often negligible, amount of chlorophyll remaining due to the destruction of chlorophyll during aging.

Preferably, the homogenized tobacco material contains at least 0.1 milligrams of chlorophyll per gram on a dry weight basis. The presence of chlorophyll in the substrate at a level greater than 0.1 milligrams per gram of homogenized tobacco material on a dry weight basis is a reliable indication that dried green tobacco material has been included.

Preferably, the homogenized tobacco material contains at least about 0.2 milligrams of chlorophyll per gram, more preferably at least about 0.5 milligrams of chlorophyll per gram, more preferably at least about 1.0 milligrams of chlorophyll per gram, more preferably at least about 1.5 milligrams of chlorophyll per gram, more preferably at least about 2.0 milligrams of chlorophyll per gram, more preferably at least about 2.5 milligrams of chlorophyll per gram, more preferably at least about 3.0 milligrams of chlorophyll per gram on a dry weight basis.

The higher the level of dried green tobacco material used in the homogenized tobacco material, the higher the level of chlorophyll that will be present in the aerosol-generating substrate. However, even with a relatively small proportion of dried green tobacco material forming the aerosol-generating substrate, the level of chlorophyll in the substrate will be significantly higher than in a substrate prepared from aged tobacco material alone without any dried green tobacco material.

The maximum level of chlorophyll in the aerosol-generating substrate will depend on the type and amount of dried green tobacco material in the aerosol-generating substrate. Typically, homogenized tobacco material will contain less than approximately 10.0 milligrams of chlorophyll per gram, or less than approximately 8.0 milligrams of chlorophyll per gram on a dry weight basis.

The dried green tobacco material used in the aerosol-generating substrate of the present invention preferably has a chlorophyll level of at least about 0.5 milligrams of chlorophyll per gram, more preferably at least about 1.0 milligrams of chlorophyll per gram, based on dry weight.

A preferred method for measuring the chlorophyll content of a sample of homogenized tobacco material containing dried green tobacco material or of a sample of dried green tobacco material can be found in "Lichtenthaler, HK and AR Wellburn (1983), Determinations of total carotenoids and chlorophylls a and b of leaf extracts in different solvents; Biochemical Society Transactions 11:591-592."

According to this method, an aqueous 80% acetone extract is obtained from a sample of homogenized tobacco material and the absorbance of the extract at specific wavelengths is measured using a spectrophotometer. The level of chlorophyll a and chlorophyll b can then be calculated using the equations below:

Chlorophyll a (µg/ml) = 12.21 (A ₆₆₃ ) - 2.81 (A ₆₄₆ )

Chlorophyll b (µg/ml) = 20.13 (A ₆₄₆ ) - 5.03 (A ₆₆₃ )

where A ₆₆₃ is the measured absorbance at 663 nm, and A ₆₄₆ is the measured absorbance at 646 nm. The chlorophyll values determined above with respect to the homogenized tobacco material of the present invention correspond to the total chlorophyll content, which is the sum of the chlorophyll a and chlorophyll b content.

An alternative method for measuring the chlorophyll content of a sample of homogenized tobacco material containing dried green tobacco material or of a sample of dried green tobacco material can be found in "Porra, RJ (2002) The chequered history of the development and use of simultaneous equations for the accurate determination of chlorophylls a and b (Photosynthesis Research 73: 149-156), where the alternative equations used are:

Chlorophyll a (µg/ml) = _12.25 (A _663.6 ) - 2.55 (A _646.6)

Chlorophyll b (µg/ml) = 20.31 (A _646.6) - 4.91 (A _663.6)

where A _663.6 is the measured absorbance at 663.6 nm, and A _646.6 is the measured absorbance at 646.6 nm.

All other components of the dried green tobacco material mentioned below can be measured using suitable GC-MS or LC-MS techniques, which should be well known to those skilled in the art.

It has been found that the inclusion of dried green tobacco material in the aerosol-generating substrate of the present invention provides the advantage of reducing the level of asparagine in the aerosol-generating substrate compared to an equivalent aerosol-generating substrate obtained from aged tobacco material alone.

Preferably, the homogenized tobacco material contains no more than about 2.5 milligrams asparagine per gram, more preferably no more than about 2.0 milligrams asparagine per gram, more preferably no more than about 1.5 milligrams asparagine per gram, more preferably no more than about 0.75 milligrams asparagine per gram, and most preferably no more than about 0.3 milligrams asparagine per gram on a dry weight basis.

The aerosol-generating substrate of the present invention will typically contain a lower level of asparagine than an aerosol-generating substrate obtained from aged tobacco material alone, since it has been found that the level of asparagine in tobacco leaves increases significantly during the aging process. For example, for some types of tobacco, the level of asparagine in tobacco leaves after aging of the tobacco leaves has been found to be more than 20 times higher than in the case of unaged green tobacco leaves.

Preferably, the dried green tobacco material has not been genetically modified and, in particular, it has not been genetically modified to reduce its asparagine content.

Preferably, the dried green tobacco material is substantially free of added asparaginase. Thus, the asparaginase present in the dried green tobacco material is only that asparaginase that is naturally present.

The level of asparagine in tobacco leaves varies depending on the type of tobacco. In some preferred embodiments, the aerosol-generating substrate comprises dried green tobacco material that is derived from Burley tobacco. The dried green Burley tobacco material preferably contains no more than about 0.5 milligrams of asparagine per gram on a dry weight basis.

The asparagine content of the homogenized tobacco material can be measured using known spectroscopic techniques. A preferred method for determining the asparagine content is described in MP 1471 rev 5 (2011) of Chelab Silliker S.r.l. Merieux Nutrisciences Company. Another suitable method is described in UNI EN ISO 13903:2005. Another suitable method is described in "Evaluation of the Content of Free Amino Acids in Tobacco by a New Liquid Chromatography-Tandem Mass Spectrometry Technique; S.C. Moldoveanu et al." (DOI: 10.1515/cttr-2015-0023).

Accordingly, the resulting aerosol generated from the aerosol-generating substrate of the present invention provides the advantage of having a significantly lower level of acrylamide, which is formed from asparagine when the aerosol-generating substrate is heated.

Preferably, when the aerosol-generating substrate of the present invention is heated under the conditions of Test Method A, an aerosol is generated containing no more than about 4 micrograms of acrylamide per gram of substrate, preferably no more than about 3 micrograms of acrylamide per gram of substrate.

In preferred embodiments of the present invention, wherein the aerosol-generating substrate comprises dried green tobacco material from Burley tobacco, the level of acrylamide in the aerosol generated from the substrate when the substrate is heated according to Test Method A is preferably no more than about 4 micrograms of acrylamide per gram of substrate, preferably no more than about 3 micrograms of acrylamide per gram of substrate.

For the purposes of the present invention, the aerosol-generating substrate is heated according to "test method A". According to test method A, an aerosol-generating article that contains an aerosol-generating substrate is heated in a holder of a tobacco heating system 2.2 (THS2.2 holder) according to a machine smoking regimen specified by Health Canada. For the purposes of performing test method A, the aerosol-generating substrate is provided in an aerosol-generating article that is compatible with the THS2.2 holder.

The holder of the tobacco heating system 2.2 (THS2.2 holder) corresponds to the commercially available IQOS device (Philip Morris Products SA, Switzerland) described in Smith et al., 2016, Regul. Toxicol. Pharmacol. 81 (S2) S82-S92. Aerosol-generating products for use in combination with the IQOS device are also commercially available.

The Health Canada smoking regimen is a clearly defined and approved smoking protocol as defined in Health Canada 2000 - Tobacco Products Information Regulations SOR/2000-273, Appendix 2; published by Justice Canada. The test method is described in ISO/TR 19478-1:2014. The Health Canada smoking test collects aerosol from a sample of an aerosol-generating substrate over 12 puffs with a puff volume of 55 millimetres, a puff duration of 2 seconds and an inter-puff interval of 30 seconds, with all ventilation blocked if ventilation is present.

Thus, in the context of the present invention, the expression "under heating the aerosol-generating substrate according to test method A" means heating the aerosol-generating substrate in the THS2.2 holder according to the machine smoking mode regulated by Health Canada, as defined in Health Canada 2000 - Tobacco Products Information Regulations SOR/2000-273, Appendix 2; published by the Department of Justice Canada, wherein the test method is described in ISO/TR 19478-1:2014.

For analysis purposes, the aerosol generated by heating the aerosol-generating substrate is captured using a suitable device depending on the analysis method to be used. The aerosol can then be analyzed using known spectroscopic techniques, such as liquid chromatography or gas chromatography techniques, which should be known to those skilled in the art.

It has been found that the inclusion of dried green tobacco material in the aerosol-generating substrate of the present invention further provides the advantage of reducing the ammonia level in the aerosol-generating substrate compared to an equivalent aerosol-generating substrate obtained from aged tobacco material alone.

Preferably, the homogenized tobacco material contains no more than about 0.5 milligrams of ammonia per gram, more preferably no more than about 0.2 milligrams of ammonia per gram, and most preferably no more than about 0.1 milligrams of ammonia per gram, based on dry weight. The aerosol-generating substrate of the present invention will generally contain a lower level of ammonia than an aerosol-generating substrate obtained from aged tobacco material alone, since it has been found that the level of ammonia in tobacco leaves increases significantly during the aging process. For example, for some types of tobacco, it has been found that the level of ammonia in tobacco leaves after aging of the tobacco leaves is more than 20 times higher than in unaged green tobacco leaves.

The level of ammonia in homogenised tobacco material can be measured according to the Coresta Centre recommended method No. 79 “Determination of ammonia content in tobacco and tobacco products by ion chromatographic analysis” (March 2018).

The level of ammonia in tobacco leaves varies depending on the type of tobacco. In certain preferred embodiments, the aerosol-generating substrate comprises dried green tobacco material that is derived from Burley tobacco. The dried green tobacco material from Burley tobacco preferably contains no more than about 0.2 milligrams of ammonia per gram on a dry weight basis.

Accordingly, the resulting aerosol generated from the aerosol-generating substrate according to the present invention provides the advantage of having a significantly lower level of ammonia that evaporates from the aerosol-generating substrate during heating.

Preferably, when the aerosol-generating substrate of the present invention is heated under the conditions of Test Method A, an aerosol is generated containing no more than about 40 micrograms of ammonia per gram of substrate, preferably no more than about 30 micrograms of ammonia per gram of substrate.

In preferred embodiments of the present invention, wherein the aerosol-generating substrate comprises dried green tobacco material from Burley tobacco, the level of ammonia in the aerosol generated from the substrate upon heating the substrate according to Test Method A is preferably no more than about 40 micrograms of acrylamide per gram of substrate, preferably no more than about 30 micrograms of ammonia per gram of substrate.

It has been found that the inclusion of dried green tobacco material in the aerosol-generating substrate of the present invention further provides the advantage of reducing the level of total free amino acids in the aerosol-generating substrate compared to an equivalent aerosol-generating substrate obtained from aged tobacco material alone.

Preferably, the homogenized tobacco material contains no more than about 12 milligrams of total free amino acids per gram, more preferably no more than about 8 milligrams of total free amino acids per gram, and most preferably no more than about 6 milligrams of total free amino acids per gram, based on dry weight. The aerosol-generating substrate of the present invention will generally contain a lower level of total free amino acids than an aerosol-generating substrate obtained from aged tobacco material alone, since it has been found that the level of total free amino acids in tobacco leaves increases significantly during the aging process. For example, for some types of tobacco, the level of total free amino acids in tobacco leaves after aging is more than 5 times higher than in unaged green tobacco leaves.

The level of total free amino acids in tobacco leaves varies depending on the type of tobacco. In certain preferred embodiments, the aerosol-generating substrate comprises dried green tobacco material that is derived from Burley tobacco. The dried green tobacco material from Burley tobacco preferably contains no more than about 20 milligrams of total free amino acids per gram on a dry weight basis.

Accordingly, the resulting aerosol generated from the aerosol-generating substrate according to the present invention provides the advantage of having significantly lower levels of hydrogen sulfide and methanethiol, which are formed from free amino acids in the aerosol-generating substrate during heating.

Preferably, when the aerosol-generating substrate of the present invention is heated under the conditions of Test Method A, an aerosol is generated containing no more than about 6 micrograms of hydrogen sulfide per gram of substrate, preferably no more than about 5 micrograms of hydrogen sulfide per gram of substrate.

In preferred embodiments of the present invention, wherein the aerosol-generating substrate comprises dried green tobacco material from Burley tobacco, the level of hydrogen sulfide in the aerosol generated from the substrate upon heating the substrate according to Test Method A is preferably no more than about 6 micrograms of hydrogen sulfide per gram of substrate, preferably no more than about 5 micrograms of hydrogen sulfide per gram of substrate.

Preferably, when the aerosol-generating substrate of the present invention is heated under the conditions of Test Method A, an aerosol is generated containing no more than 10 micrograms of methanethiol per gram of substrate, preferably no more than about 9 micrograms of methanethiol per gram of substrate.

In preferred embodiments of the present invention, wherein the aerosol-generating substrate comprises dried green tobacco material from Burley tobacco, the level of methanethiol in the aerosol generated from the substrate upon heating the substrate according to Test Method A is preferably no more than about 10 micrograms methanethiol per gram of substrate, preferably no more than about 9 micrograms methanethiol per gram of substrate.

The reduction in the level of hydrogen sulfide and methanethiol in the aerosol generated from the aerosol generating substrate of the present invention provides an advantage since these compounds are known to be responsible for undesirable sulfur odors during heating.

It has further been found that the inclusion of dried green tobacco material in the aerosol-generating substrate of the present invention provides the advantage of reducing the level of certain TSNAs (tobacco-specific nitrosamines) in the aerosol-generating substrate compared to an equivalent aerosol-generating substrate made from aged tobacco material alone.

For example, the aerosol-generating substrate of the present invention will typically contain a lower level of NNN (N-nitrosonornicotine) than an aerosol-generating substrate obtained from aged tobacco material alone, since the level of NNN and other TSNAs in tobacco leaves has been found to increase significantly during the aging process. For some types of tobacco, the level of NNN in tobacco leaves has been found to be more than 5 times higher after aging of the tobacco leaves than in unaged green tobacco leaves.

The level of NNN in tobacco leaves varies depending on the type of tobacco. In some preferred embodiments, the aerosol-generating substrate comprises dried green tobacco material that is derived from Burley tobacco. The dried green tobacco material from Burley tobacco preferably contains no more than about 500 nanograms of NNN per gram on a dry weight basis.

Therefore, the resulting aerosol generated from the aerosol-generating substrate according to the present invention has a significantly lower level of NNN that evaporates from the aerosol-generating substrate during heating.

It has been found that the incorporation of dried green tobacco material into the aerosol-generating substrate of the present invention provides a significant increase in the level of phosphatidylethanolamine (PE) in the aerosol-generating substrate compared to an equivalent aerosol-generating substrate obtained from aged tobacco material alone. PE is an extra-chloroplast lipid found in plant membranes. The presence of PE above a certain threshold level is a reliable indicator of the incorporation of dried green tobacco material into the aerosol-generating substrate. It has been found that the level of some of the PE molecular compounds, including PE 36:6, PE 34:3, PE 36:5 and PE 34:2, is at least 8 times higher, in some cases at least 10 times higher, in the dried green tobacco material than in the aged tobacco material from the same type of tobacco.

The term "PE 36:6" refers to PE molecular compounds that have 36 carbons in two acyl chains and a total of 6 double bonds. The same terminology applies to the other molecular substances listed above.

Preferably, the aerosol generated from the aerosol-generating substrate according to the present invention during test method A further comprises at least about 0.1 micrograms of nicotine per gram of substrate, more preferably at least about 1 microgram of nicotine per gram of substrate, more preferably at least about 2 micrograms of nicotine per gram of substrate. Preferably, the aerosol comprises up to about 10 micrograms of nicotine per gram of substrate, more preferably up to about 7.5 micrograms of nicotine per gram of substrate, more preferably up to about 4 micrograms of nicotine per gram of substrate. For example, the aerosol may comprise from about 0.1 micrograms to about 10 micrograms of nicotine per gram of substrate, or from about 1 microgram to about 7.5 micrograms of nicotine per gram of substrate, or from about 2 micrograms to about 4 micrograms of nicotine per gram of substrate. In some embodiments of the present invention, the aerosol may contain zero micrograms of nicotine.

Various methods known in the art may be used to measure the amount of nicotine in an aerosol.

The aerosol formed from the aerosol-generating substrate of the present invention during test method A may further comprise at least about 5 milligrams of aerosol forming agent per gram of aerosol-generating substrate, or at least about 10 milligrams of aerosol forming agent per gram of substrate, or at least about 15 milligrams of aerosol forming agent per gram of substrate. Alternatively or additionally, the aerosol may comprise up to about 30 milligrams of aerosol forming agent per gram of substrate, or up to about 25 milligrams of aerosol forming agent per gram of substrate, or up to about 20 milligrams of aerosol forming agent per gram of substrate. For example, the aerosol may contain from about 5 milligrams to about 30 milligrams of aerosol forming agent per gram of substrate, or from about 10 milligrams to about 25 milligrams of aerosol forming agent per gram of substrate, or from about 15 milligrams to about 20 milligrams of aerosol forming agent per gram of substrate. In alternative embodiments, the aerosol may contain less than 5 milligrams of aerosol forming agent per gram of substrate. This may be appropriate, for example, if the aerosol forming agent is provided separately within the aerosol-generating article or aerosol-generating device.

Aerosol forming substances suitable for use in the present invention are presented below.

Various methods known in the art can be used to measure the amount of aerosol forming substance in an aerosol.

Preferably, the homogenized tobacco material of the aerosol-generating substrates according to the present invention comprises at least about 1 percent by weight of dried green tobacco material on a dry weight basis. Preferably, the homogenized tobacco material comprises at least about 2 percent by weight of dried green tobacco material, more preferably at least about 4 percent by weight of dried green tobacco material, more preferably at least about 6 percent by weight of dried green tobacco material, more preferably at least about 8 percent by weight of dried green tobacco material, more preferably at least about 10 percent by weight of dried green tobacco material on a dry weight basis.

The homogenized tobacco material may contain up to about 75 percent by weight of dried green tobacco material on a dry weight basis. Preferably, the homogenized tobacco material contains up to about 70 percent by weight of dried green tobacco material, more preferably up to about 65 percent by weight of dried green tobacco material, more preferably up to about 60 percent by weight of dried green tobacco material, more preferably up to about 55 percent by weight of dried green tobacco material, more preferably up to about 50 percent by weight of dried green tobacco material on a dry weight basis.

For example, the homogenized tobacco material may contain from about 1 percent to about 75 percent by weight of dried green tobacco material, or from about 2 percent to about 70 percent by weight of dried green tobacco material, or from about 4 percent to about 65 percent by weight of dried green tobacco material, or from about 6 percent to about 60 percent by weight of dried green tobacco material, or from about 8 percent to about 55 percent by weight of dried green tobacco material, or from about 10 percent to about 50 percent by weight of dried green tobacco material on a dry weight basis.

In some particularly preferred embodiments of the present invention, the homogenized tobacco material comprises from about 10 percent by weight to about 30 percent by weight of dried green tobacco material, based on dry weight.

In some embodiments of the present invention, the aerosol-generating plant material that forms the homogenized tobacco material may contain at least 98 percent by weight of dried green tobacco material, or at least 95 percent by weight of dried green tobacco material, or at least 90 percent by weight of dried green tobacco material based on the dry weight of the plant material. Therefore, in such embodiments, the aerosol-generating substrate contains dried green tobacco material substantially free of aged tobacco material. For example, the plant material that forms the homogenized tobacco material may contain about 100 percent by weight of dried green tobacco material.

In alternative embodiments of the present invention, the homogenized tobacco material may comprise dried green tobacco material in admixture with aged tobacco material, as described below.

As an alternative or in addition to the aged tobacco material, the homogenized tobacco material may comprise an aerosol-generating plant material obtained from one or more plants, including, but not limited to, hemp, tea, ginger, eucalyptus, cloves, mint, anise, rosemary, chamomile, thyme, and dill seed.

In the following description of the present invention, the term "plant material" is used to generally denote a plant aerosol-generating material that is used to produce an aerosol-generating substrate. The plant material may consist essentially of dried green tobacco material, or it may be a mixture of dried green tobacco material with aged tobacco material or another aerosol-generating plant material, as defined above. Preferably, the plant material is present in the form of plant particles, which may consist essentially of dried green tobacco particles, or they may be a mixture of dried green tobacco particles with aged tobacco particles. The term "plant material" does not include any inert plant material that is included in the aerosol-generating substrate and that does not contribute to the generation of the aerosol upon heating of the aerosol-generating substrate.

Preferably, the homogenized tobacco material according to the present invention further comprises at least about 1 percent by weight of aged tobacco material. For example, the homogenized tobacco material may comprise at least about 2 percent by weight of aged tobacco material, or at least about 4 percent by weight of aged tobacco material, or at least about 6 percent by weight of aged tobacco material, or at least about 8 percent by weight of aged tobacco material, or at least about 10 percent by weight of aged tobacco material, based on dry weight.

The homogenized tobacco material may contain up to about 75 percent by weight of aged tobacco material, or up to about 70 percent by weight of aged tobacco material, or up to at least about 65 percent by weight of aged tobacco material, up to at least about 60 percent by weight of aged tobacco material, or up to at least about 55 percent by weight of aged tobacco material, or up to at least about 50 percent by weight of aged tobacco material on a dry weight basis.

The aged tobacco material is preferably present in the form of aged tobacco particles.

The term "aged tobacco material" is used herein to refer to material obtained from tobacco plants that have been subjected to a known aging process for at least 5 days. Aged tobacco material, such as aged tobacco leaves, will typically be brown in color and have a chlorophyll level of no more than 0.25 milligrams per gram on a dry weight basis.

The ratio of dried green tobacco material to mature tobacco material in the homogenized tobacco material may vary depending on the desired content of dried green tobacco material in the homogenized tobacco material. Preferably, the ratio of dried green tobacco material to mature tobacco material in the homogenized tobacco material is no more than 1 to 1 (1:1). In such embodiments, the weight amount of mature tobacco material in the homogenized tobacco material is equal to or greater than the weight amount of dried green tobacco material in the homogenized tobacco material, based on dry weight.

As used herein, the term "tobacco material," whether referring to cured green tobacco material or aged tobacco material, may refer to any plant material of the genus Nicotiana. The term "tobacco particles" includes ground or powdered tobacco leaf lamellae, ground or powdered tobacco leaf stalks, tobacco dust, tobacco fines, and other particulate tobacco by-products generated during the processing, handling, and shipping of tobacco. In a preferred embodiment, substantially all of the tobacco material is derived from tobacco leaf lamellae. In contrast, isolated nicotine and nicotine salts are compounds derived from tobacco but are not considered tobacco material for the purposes of the present invention and are not included in the percentage of plant material.

The tobacco material may be prepared from one or more varieties of tobacco plants. Any type of tobacco may be used in the blend. Examples of tobacco types that may be used for green cured tobacco material include, but are not limited to, Burley tobacco, Maryland tobacco, Oriental tobacco, Virginia tobacco and other specialty tobaccos. Examples of tobacco types that may be used for Aged Type Tobacco include, but are not limited to, sun-cured tobacco, flue-cured tobacco, Burley tobacco, Maryland tobacco, Oriental tobacco, Virginia tobacco and other specialty tobaccos.

Burley tobacco plays an important role in many tobacco blends. Burley tobacco has a recognizable taste and aroma, and it is also capable of absorbing large quantities of sauce.

Oriental tobacco has small leaves and pronounced aromatic qualities. However, Oriental tobacco has a milder taste than, for example, Burley tobacco. Therefore, Oriental tobacco is usually used in relatively small proportions in tobacco blends.

Flue-curing is a method of drying tobacco that is especially widely used with Virginia tobaccos. During the flue-curing process, heated air is circulated through tightly packed tobacco. During the first stage, the tobacco leaves turn yellow and wilt. During the second stage, the leaf blades are completely dry. During the third stage, the leaf petioles are completely dry.

Kasturi, Maduro and Yatim are subtypes of sun-cured tobacco that can be used.

Cured green tobacco material or aged tobacco material may contain a mixture of different types of tobacco.

The tobacco material may have a nicotine content of at least about 2.5 percent by weight on a dry weight basis. More preferably, the tobacco material may have a nicotine content of at least about 3 percent, even more preferably at least about 3.2 percent, still more preferably at least about 3.5 percent, most preferably at least about 4 percent by weight on a dry weight basis. The aging process does not appear to significantly affect the nicotine level of the tobacco leaves, and therefore these values apply to both cured green tobacco material and aged tobacco material, if any.

Nicotine may optionally be included in the aerosol-generating substrate, although it is considered a material other than tobacco for the purposes of the present invention. Nicotine may comprise one or more nicotine salts selected from the list consisting of nicotine lactate, nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine benzoate, nicotine pectate, nicotine alginate and nicotine salicylate. Nicotine may be included in addition to low-nicotine tobacco, or nicotine may be included in an aerosol-generating substrate that has a reduced or zero tobacco content.

Preferably, the homogenized tobacco material comprises at least about 0.1 mg nicotine per gram of substrate on a dry weight basis. More preferably, the homogenized tobacco material comprises at least about 0.5 mg nicotine per gram of substrate, more preferably at least about 1 mg nicotine per gram of substrate, more preferably at least about 1.5 mg nicotine per gram of substrate, more preferably at least about 2 mg nicotine per gram of substrate, more preferably at least about 3 mg nicotine per gram of substrate, more preferably at least about 4 mg nicotine per gram of substrate, more preferably at least about 5 mg nicotine per gram of substrate on a dry weight basis.

Preferably, the homogenized tobacco material comprises up to about 50 mg nicotine per gram of substrate on a dry weight basis. More preferably, the homogenized tobacco material comprises up to about 45 mg nicotine per gram of substrate, more preferably up to about 40 mg nicotine per gram of substrate, more preferably up to about 35 mg nicotine per gram of substrate, more preferably up to about 30 mg nicotine per gram of substrate, more preferably up to about 25 mg nicotine per gram of substrate, more preferably up to about 20 mg nicotine per gram of substrate on a dry weight basis.

For example, the homogenized tobacco material may contain from about 0.1 mg to about 50 mg nicotine per gram of substrate, or from about 0.5 mg to about 45 mg nicotine per gram of substrate, or from about 1 mg to about 40 mg nicotine per gram of substrate, or from about 2 mg to about 35 mg nicotine per gram of substrate, or from about 5 mg to about 30 mg nicotine per gram of substrate, or from about 10 mg to about 25 mg nicotine per gram of substrate, or from about 15 mg to about 20 mg nicotine per gram of substrate on a dry weight basis. In some preferred embodiments of the present invention, the homogenized tobacco material contains from about 1 mg to about 20 mg nicotine per gram of substrate on a dry weight basis.

The specified ranges of nicotine content in the homogenized tobacco material include all forms of nicotine that may be present in the homogenized tobacco material, including nicotine originally present in the tobacco material, as well as nicotine that is optionally separately added to the homogenized tobacco material, for example, in the form of a nicotine salt.

The nicotine content of homogenised tobacco material can be measured according to the hexane method described in Coresta recommended method No. 62 “Determination of nicotine in tobacco and tobacco products using gas chromatographic analysis” (April 2020).

The homogenized tobacco material preferably comprises at least about 55 percent by weight of plant material, including the dried green tobacco material described above, more preferably at least about 60 percent by weight of plant material, and more preferably at least about 65 percent by weight of plant material on a dry weight basis. The homogenized tobacco material preferably comprises no more than about 95 percent by weight of plant material, more preferably no more than about 90 percent by weight of plant material, and more preferably no more than about 85 percent by weight of plant material on a dry weight basis. For example, the homogenized tobacco material can comprise from about 55 percent to about 95 percent by weight of plant material, or from about 60 percent to about 90 percent by weight of plant material, or from about 65 percent to about 85 percent by weight of plant material on a dry weight basis. In one particularly preferred embodiment, the homogenized tobacco material comprises approximately 75 percent by weight of plant material on a dry weight basis.

In some preferred embodiments, the total weight amount of plant material is no more than about 75 percent by weight on a dry weight basis.

In this way, the plant material is mixed with one or more other components to produce a homogenized tobacco material.

As defined above, the homogenized tobacco material further comprises an aerosol former. When vaporized, the aerosol former is capable of transporting other vaporized compounds into the aerosol, such as nicotine and flavoring substances released from the homogenized tobacco material upon heating. Aerosolization of a particular compound from the homogenized tobacco material is not solely determined by the boiling point of that compound. The amount of compound that is released as an aerosol can be affected by the physical form of the substrate, as well as other components that are also present in the substrate. The stability of the compound as a function of the temperature and time of aerosol formation will also affect the amount of compound that is present in the aerosol.

Aerosol formers suitable for inclusion in the homogenized tobacco material are known in the art and include, but are not limited to: polyhydric alcohols such as triethylene glycol, propylene glycol, 1,3-butanediol and glycerol; esters of polyhydric alcohols such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. The homogenized tobacco material may comprise a single aerosol former or a combination of two or more aerosol formers.

If the substrate is intended for use in an aerosol generating article for an electric aerosol generating system having a heating element, the aerosol forming substance is preferably glycerin.

The amount of aerosol forming agent may be adapted depending on the composition of the homogenized tobacco material, such as the type or amount of plant material, in order to obtain an aerosol having the desired levels of flavor compounds from the plant material. The amount of aerosol forming agent may also be adapted depending on the method by which the homogenized tobacco material is intended to be heated during use and, in particular, depending on the temperature to which the homogenized tobacco material will be heated during heating of the aerosol-generating article in the associated aerosol-generating device.

The homogenized tobacco material preferably has an aerosol forming agent content of from about 5 percent to about 55 percent by weight on a dry weight basis, such as from about 10 percent to about 45 percent by weight on a dry weight basis, or from about 15 percent to about 40 percent by weight on a dry weight basis.

The aerosol former may be present in an amount from about 5 percent to about 30 percent by weight on a dry weight basis. For example, in homogenized tobacco materials according to some preferred embodiments of the present invention, the aerosol former preferably is present in an amount from about 5 percent to about 30 percent by weight, more preferably from about 10 percent to about 25 percent by weight, more preferably from about 15 percent to about 20 percent by weight on a dry weight basis.

Alternatively, the aerosol former may be present in an amount from about 15 percent to about 55 percent by weight on a dry weight basis. For example, in the homogenized tobacco materials of alternative preferred embodiments of the present invention, the aerosol former preferably is present in an amount from about 15 percent to about 55 percent by weight, more preferably from about 25 percent to about 50 percent by weight, more preferably from about 35 percent to about 45 percent by weight on a dry weight basis.

In other embodiments, the homogenized tobacco material may have an aerosol forming agent content of from about 1 percent to about 5 percent by weight on a dry weight basis. For example, if the substrate is intended for use in an aerosol-generating article in which the aerosol forming agent is retained in a reservoir separate from the substrate, the substrate may have an aerosol forming agent content greater than 1 percent and less than about 5 percent. In such embodiments, the aerosol forming agent is vaporized by heating, and a stream of the aerosol forming agent is brought into contact with the homogenized tobacco material, such that flavoring substances from the homogenized tobacco material are entrained in the aerosol.

The aerosol forming agent may act as a humectant in the homogenized tobacco material.

As defined above, the homogenized tobacco material further comprises a binder for changing the mechanical properties of the plant material, wherein the binder is included in the homogenized tobacco material during manufacturing as described herein. Suitable exogenous binders will be known to those skilled in the art and include, but are not limited to: gums, such as, for example, guar gum, xanthan gum, acacia and locust bean gum; cellulose binders, such as, for example, hydroxypropyl cellulose, carboxymethyl cellulose (CMC), hydroxyethyl cellulose, methyl cellulose and ethyl cellulose; polysaccharides, such as, for example, starches, organic acids, such as alginic acid, salts of conjugate bases with organic acids, such as sodium alginate, agar and pectins; and combinations thereof. Preferably, the binder comprises guar gum.

Preferably, the binder is present in an amount of from about 1 percent to about 10 percent by weight, preferably in an amount of from about 2 percent to about 9 percent by weight, more preferably in an amount of from about 3 percent by weight to about 8 percent by weight on a dry weight basis.

In some embodiments, the homogenized tobacco material preferably comprises from about 1 percent to about 10 percent by weight of a binder on a dry weight basis, wherein the binder is most preferably guar gum. For example, in the aerosol-generating articles according to the first preferred embodiment of the present invention, the homogenized tobacco material preferably comprises from about 1 percent to about 10 percent by weight of a binder on a dry weight basis, wherein the binder is most preferably guar gum.

In some embodiments, the homogenized tobacco material preferably comprises from about 2 percent to about 10 percent by weight of a binder on a dry weight basis, wherein the binder is most preferably a cellulose ether. For example, in the aerosol-generating articles of the second preferred embodiment, the homogenized tobacco material preferably comprises from about 2 percent to about 10 percent by weight of a binder on a dry weight basis, wherein the binder is preferably a cellulose ether. Particularly preferably, the binder is carboxymethyl cellulose (CMC).

In addition, the homogenized tobacco material of any embodiment may optionally further comprise additional cellulose. For example, the homogenized tobacco material may comprise from about 5 percent by weight to about 50 percent by weight of additional cellulose.

As used herein, the term "additional cellulose" encompasses any cellulosic material included in the homogenized tobacco material and derived from other than the tobacco material provided in the homogenized tobacco material. Thus, the additional cellulose is included in the homogenized tobacco material in addition to the tobacco material as a source of cellulose separate and distinct from any cellulose originally provided in the tobacco material. The additional cellulose is typically derived from a plant other than the tobacco material. Preferably, the additional cellulose is present as an inert cellulose material that is organoleptically inert and therefore does not significantly affect the organoleptic characteristics of the aerosol generated from the aerosol-generating substrate. For example, the additional cellulose is preferably a tasteless and odorless material.

The additional pulp may consist of a single type of cellulosic material, or it may be a combination of different types of cellulosic materials that provide different properties, as described in more detail below.

It is believed that the additional cellulose included in the homogenized tobacco material of the present invention provides additional structure and reinforcement for binding and supporting the plant material and aerosol forming agent within the homogenized tobacco material.

It has been found that the inclusion of additional cellulose is particularly useful in homogenized tobacco materials in which the binder comprises a cellulose ether as described above. It has been found that a combination of cellulose ether and additional cellulose material at certain specified levels and within certain ratios indicated below provides the advantage of producing a homogenized tobacco material having improved tensile strength and uniformity.

Preferably, the ratio of additional cellulose material to cellulose ether in the homogenized tobacco material is at least 2.

Preferably, the additional cellulose comprises cellulose powder. The term "cellulose powder" is used herein to denote purified cellulose material in powder form, which is obtained from cellulose fibers. Preferably, the cellulose powder is formed by particles with an average particle size of less than about 100 microns. The cellulose powder may be present in the form of microcrystalline cellulose. A suitable cellulose powder for use in the present invention is available as microcrystalline cellulose type SK-105 or SK-101, or cellulose powder type M-60 from Gumix International Inc., New Jersey.

Preferably, the amount of cellulose powder corresponds to at least about 5 percent by weight of the homogenized tobacco material, more preferably at least about 6 percent by weight of the homogenized tobacco material, more preferably at least about 7 percent by weight of the homogenized tobacco material, and more preferably at least about 8 percent by weight of the homogenized tobacco material, based on dry weight.

The amount of cellulose powder can be adjusted to a level higher than the specified minimum level, depending on the weight amount of other components in the homogenized tobacco material and, in particular, depending on the weight amount of plant material. In some embodiments, the cellulose powder can replace a proportion of plant material in the homogenized tobacco material without significantly affecting the characteristics of the generated aerosol.

Preferably, the amount of cellulose powder corresponds to no more than about 45 percent by weight of the homogenized tobacco material, more preferably no more than about 40 percent by weight of the homogenized tobacco material on a dry weight basis.

In some embodiments, such as embodiments having a relatively high level of plant material in the homogenized tobacco material, the amount of cellulose powder may be relatively low. In such embodiments, the amount of cellulose powder may be from about 5 percent by weight to about 15 percent by weight of the homogenized tobacco material, or from about 6 percent by weight to about 12 percent by weight of the homogenized tobacco material, or from about 7 percent by weight to about 11 percent by weight of the homogenized tobacco material, or from about 8 percent by weight to about 10 percent by weight of the homogenized tobacco material on a dry weight basis.

In other embodiments, such as embodiments having a relatively low level of aerosol-generating plant material in the homogenized tobacco material, the amount of cellulose powder can be relatively high. In such embodiments, the amount of cellulose powder can be from about 15 percent by weight to about 45 percent by weight of the homogenized tobacco material, or from about 20 percent by weight to about 40 percent by weight of the homogenized tobacco material, or from about 25 percent by weight to about 35 percent by weight of the homogenized tobacco material on a dry weight basis.

Preferably, if the homogenized tobacco material comprises a cellulose ether and a cellulose powder, the ratio by weight of the cellulose powder to the cellulose ether in the homogenized tobacco material is at least about 1.5, i.e. the amount of cellulose powder is at least 1.5 times the amount of cellulose ether. More preferably, the ratio by weight of the cellulose powder to the cellulose ether in the homogenized tobacco material is at least about 1.6, more preferably at least about 1.8.

As an alternative or in addition to the cellulose powder, the additional cellulose may comprise cellulose fibers. The term "cellulose fibers" is used herein to denote fibers obtained directly from plant-based materials, each fiber having a length that is significantly greater than its width. The cellulose fibers preferably have a fiber length of at least 400 microns. Cellulose fibers suitable for use in the present invention include, for example, wood pulp fibers. A source of cellulose fibers suitable for use in the present invention is available as "ECT Bleached Hardwood Kraft Pulp" from Storaenso, Sweden.

Cellulose fibers can, as an advantage, act as a mechanical reinforcement in the homogenized tobacco material forming the aerosol-generating substrate of the aerosol-generating articles according to the present invention. Cellulose fibers are capable of improving the binding of plant material in the homogenized tobacco material and providing an improvement in tensile strength, in particular in combination with a cellulose ether binder.

Preferably, the amount of cellulose fibers corresponds to at least about 3 percent by weight of the homogenized tobacco material on a dry weight basis, more preferably at least about 4 percent by weight of the homogenized tobacco material, more preferably at least about 5 percent by weight of the homogenized tobacco material, and more preferably at least about 6 percent by weight of the homogenized tobacco material on a dry weight basis.

Preferably, the amount of cellulose fibers corresponds to no more than about 12 percent by weight of the homogenized tobacco material, more preferably at least about 11 percent by weight of the homogenized tobacco material, more preferably at least about 10 percent by weight of the homogenized tobacco material, more preferably at least about 8 percent by weight of the homogenized tobacco material on a dry weight basis.

For example, the homogenized tobacco material may contain from about 3 percent by weight to about 12 percent by weight cellulose fibers, or from about 4 percent by weight to about 11 percent by weight cellulose fibers, or from about 5 percent by weight to about 10 percent by weight cellulose fibers, or from about 6 percent by weight to about 8 percent by weight cellulose fibers on a dry weight basis.

Preferably, if the homogenized tobacco material contains cellulose ether and cellulose fibers, the ratio by weight of cellulose fibers to cellulose ether in the homogenized tobacco material is at least about 0.5, i.e. the amount of cellulose powder is at least half the amount of cellulose ether. More preferably, the ratio by weight of cellulose fibers to cellulose ether in the homogenized tobacco material is at least about 0.75, more preferably at least about 1.

In preferred embodiments, the additional cellulose comprises cellulose powder and cellulose fibers. In such embodiments, the weight ratio of cellulose powder to cellulose fibers is preferably at least about 1.5, more preferably at least about 1.75, more preferably at least about 2.

Preferably, the amount of additional cellulose provided in the homogenized tobacco material is adapted such that the total amount of additional cellulose and plant material corresponds to no more than 75 percent by weight of the homogenized tobacco material. Therefore, preferably, at least about 25 percent by weight of the homogenized tobacco material is provided by other components, including cellulose ether and aerosol forming agent.

In the aerosol-generating articles according to the second preferred embodiment of the present invention, the homogenized tobacco material preferably comprises from about 2 percent to about 10 percent by weight of cellulose ether and from about 5 percent by weight to about 50 percent by weight of additional cellulose, based on dry weight. Preferably, the ratio of additional cellulose to cellulose ether may be at least 2.

In addition to the above-described components, the homogenized tobacco material may optionally further comprise one or more lipids to assist in the diffusion of volatile components (e.g., aerosol forming agents and nicotine), wherein the lipids are included in the homogenized plant material during manufacture as described herein. Lipids suitable for inclusion in the homogenized tobacco material include, but are not limited to: medium chain triglycerides, cocoa butter, palm oil, palm kernel oil, mango butter, shea butter, soybean oil, cottonseed oil, coconut oil, hydrogenated coconut oil, candelilla wax, carnauba wax, shellac, sunflower wax, sunflower oil, rice bran and Revel A, and combinations thereof.

Alternatively or additionally, the homogenized tobacco material may further comprise a pH modifier.

Alternatively or additionally, the homogenized tobacco material may further comprise fibers for altering the mechanical properties of the homogenized tobacco material, wherein the fibers are incorporated into the homogenized tobacco material during manufacture as described herein. Exogenous fibers suitable for inclusion in the homogenized plant material are known in the art and include fibers derived from a material that is not tobacco, and a material that is not tobacco includes, but is not limited to: cellulose fibers; softwood fibers; hardwood fibers; jute fibers, and combinations thereof. Exogenous fibers derived from tobacco and/or tobacco may also be added. Any fibers added to the homogenized tobacco material are not considered to form part of the "plant material" as defined above. Prior to incorporation into the homogenized tobacco material, the fibers may be processed by suitable methods known in the art, including, but not limited to: mechanical pulping; cleaning; chemical pulping; bleaching; sulphate pulping; and combinations of the above. The fibre is usually longer than it is wide.

Suitable fibers typically have lengths greater than 400 micrometers and less than or equal to 4 mm, preferably within the range of 0.7 mm to 4 mm. Preferably, the fibers are present in an amount of at least about 2 percent by weight based on the dry weight of the substrate. The amount of fibers in the homogenized tobacco material may depend on the type of material and, in particular, on the method used to produce the homogenized tobacco material. In some embodiments, the fibers may be present in an amount of from about 2 percent by weight to about 15 percent by weight, most preferably about 4 percent by weight based on the dry weight of the substrate. For example, this level of fibers may be present when the homogenized tobacco material is in the form of a cast sheet. In other embodiments, the fibers may be present in an amount of at least about 30 percent by weight or at least about 40 percent by weight. For example, this higher fiber level will most likely be achieved if the homogenized tobacco material is plant paper obtained from a papermaking process.

In preferred embodiments of the present invention, the homogenized tobacco material comprises from about 5 percent by weight to about 30 percent by weight of an aerosol former and from about 1 percent by weight to about 10 percent by weight of a binder, based on dry weight. In such embodiments, the homogenized tobacco material preferably further comprises from about 2 percent by weight to about 15 percent by weight of fibers. Particularly preferably, the binder is guar gum.

The homogenized tobacco material is preferably present in the form of a solid or a gel. However, in some embodiments, the homogenized tobacco material may be present in the form of a solid that is not a gel. Preferably, the homogenized tobacco material is not present in the form of a film.

The homogenized tobacco material may be provided in any suitable form. For example, the homogenized tobacco material may be present in the form of one or more sheets. As used herein in connection with the present invention, the term "sheet" describes a flat element whose width and length are substantially greater than its thickness.

Alternatively or additionally, the homogenized tobacco material may be present in the form of a plurality of pellets or granules.

Alternatively or additionally, the homogenized tobacco material may be present in a form that is capable of filling a cartridge or a consumable part of a hookah, or that can be used in a hookah device. The present invention includes a cartridge or a hookah device that contains homogenized tobacco material.

Alternatively or additionally, the homogenized tobacco material may be present in the form of a plurality of strands, strips or pieces. As used herein, the term "strand" describes an elongated element of material whose length substantially exceeds its width and thickness. The term "strand" should be considered to include strips, pieces and any other homogenized tobacco material having a similar shape. The strands of homogenized tobacco material may be obtained from a sheet of homogenized plant material, for example, by cutting or shredding, or by other methods, for example, by an extrusion method.

In some embodiments, the threads may be produced in situ within the homogenized tobacco material as a result of splitting or cracking a sheet of homogenized tobacco material during the production of the homogenized tobacco material, for example, as a result of corrugating. The threads of homogenized tobacco material within the homogenized tobacco material may be separated from each other. Alternatively, each thread of homogenized tobacco material within the homogenized tobacco material may be at least partially connected to an adjacent thread or threads along the length of the threads. For example, adjacent threads may be connected by means of one or more fibers. This may be the case, for example, if the threads were produced as a result of splitting a sheet of homogenized tobacco material during the production of the homogenized tobacco material, as described above.

Preferably, the homogenized tobacco material is present in the form of one or more sheets of homogenized tobacco material. In various embodiments of the present invention, said one or more sheets of homogenized tobacco material can be obtained by a casting process. In various embodiments of the present invention, said one or more sheets of homogenized plant material can be obtained by a papermaking process. Each of said one or more sheets described herein can have an individual thickness of from 100 micrometers to 600 micrometers, preferably from 150 micrometers to 300 micrometers, most preferably from 200 micrometers to 250 micrometers. Individual thickness refers to the thickness of an individual sheet, while the cumulative thickness refers to the total thickness of all sheets that form the aerosol-generating substrate. For example, if the aerosol-generating substrate is formed from two individual sheets, then the combined thickness is the sum of the thicknesses of the two individual sheets or the measured thickness of the two sheets when the two sheets are stacked on top of each other in the aerosol-generating substrate.

Each of the one or more sheets described herein may have an individual grammage of from about 100 g/ ^m2 to about 300 g/ ^m2 , or from about 100 g/ ^m2 to about 200 g/ ^m2 .

Each of the one or more sheets described herein may have an individual density of from about 0.3 g/ ^{cm3 to} about 1.3 g/ ^cm3 , preferably from about 0.7 g/ ^cm3 to about 1.0 g/ ^cm3 .

In those embodiments of the present invention in which the aerosol-generating substrate comprises one or more sheets of homogenized tobacco material, these sheets are preferably present in the form of one or more gathered sheets. The term "gathered" as used herein is used to describe a sheet of homogenized tobacco material that is rolled, folded, or otherwise compressed or narrowed in a direction substantially transverse to the cylindrical axis of the plug or rod. The step of "gathering" the sheet may be accomplished by any suitable means that provides the necessary transverse compression of the sheet.

As used herein, the term "longitudinal" refers to the direction corresponding to the main longitudinal axis of the aerosol-generating article, which extends between the upstream and downstream ends of the aerosol-generating article. During use, air is drawn through the aerosol-generating article in the longitudinal direction. The term "transverse" refers to the direction that is perpendicular to the longitudinal axis. As used herein, the term "length" refers to the dimension of the component in the longitudinal direction, and the term "width" refers to the dimension of the component in the transverse direction. For example, in the case of a plug or rod having a circular cross-section, the maximum width corresponds to the diameter of the circle.

The term "plug" as used herein denotes a generally cylindrical element with a substantially polygonal, circular, oval or elliptical cross-section. The term "rod" as used herein refers to a generally cylindrical element with a substantially polygonal cross-section, preferably with a circular, oval or elliptical cross-section. The rod may have a length that is greater than or equal to the length of the plug. Typically, the rod has a length that is greater than the length of the plug. The rod may comprise one or more plugs, preferably aligned in the longitudinal direction.

As used herein, the terms "upstream" and "downstream" describe the relative positions of elements or portions of elements of an aerosol-generating article relative to the direction in which the aerosol is carried during use through the aerosol-generating article. The downstream end of the air flow path is the end through which the aerosol is delivered to the user of the article.

Said one or more sheets of homogenized tobacco material may be assembled transversely relative to their longitudinal axis and surrounded by a wrapper to form a continuous rod or plug. The continuous rod may be divided into a plurality of individual rods or plugs. The wrapper may be a paper wrapper or a non-paper wrapper, as described in more detail below.

Alternatively, said one or more sheets of homogenized tobacco material may be cut into threads, as described above. In such embodiments, the aerosol-generating substrate comprises a plurality of threads of homogenized tobacco material. The threads may be used to form a stopper. Typically, the width of such threads is at least about 0.2 mm, or at least about 0.5 mm. Preferably, the width of such threads is no more than about 5 mm, or about 4 mm, or about 3 mm, or about 1.5 mm. For example, the width of the threads may be from about 0.25 mm to about 5 mm, or from about 0.25 mm to about 3 mm, or from about 0.5 mm to about 1.5 mm.

The length of the threads is preferably greater than about 5 mm, for example, it is from about 5 mm to about 20 mm, or from about 8 mm to about 15 mm, or about 12 mm. Preferably, the threads have substantially the same length as each other. The length of the threads can be determined by a manufacturing process in which the rod is cut into shorter plugs, and the length of the threads corresponds to the length of the plug. The threads can be brittle, which can lead to breakage, especially during handling. In such cases, the length of some threads can be shorter than the length of the plug.

Said plurality of threads preferably extends substantially in the longitudinal direction along the length of the aerosol-generating substrate aligned with the longitudinal axis. Thus, said plurality of threads are preferably aligned substantially parallel to each other.

Each thread of homogenized tobacco material preferably has a mass to surface area ratio of at least about 0.02 milligrams per square millimeter, more preferably at least about 0.05 milligrams per square millimeter. Preferably, each thread of homogenized tobacco material has a mass to surface area ratio of no more than about 0.2 milligrams per square millimeter, more preferably no more than about 0.15 milligrams per square millimeter. The mass to surface area ratio is calculated by dividing the mass of the thread of homogenized tobacco material in milligrams by the geometric surface area of the thread of homogenized tobacco material in square millimeters.

Said one or more sheets of homogenized tobacco material may be textured by corrugating, embossing or perforating. Said one or more sheets may be textured before gathering or before cutting into threads. Preferably, the one or more sheets of homogenized tobacco material are corrugated before gathering, so that the homogenized tobacco material may be present in the form of a corrugated sheet, more preferably in the form of a collected corrugated sheet. As used herein, the term "corrugated sheet" means a sheet having a plurality of substantially parallel ridges or flutes, generally aligned with the longitudinal axis of the article.

In one embodiment, the aerosol-generating substrate may be present in the form of a single plug of homogenized tobacco material. In other embodiments, the aerosol-generating substrate may be present in the form of two or more plugs of homogenized tobacco material, wherein the plugs of homogenized tobacco material may be made of the same or different homogenized tobacco materials.

The aerosol-generating substrates of the present invention may be produced by a variety of methods, including papermaking, casting, dough reduction, extrusion, or any other suitable process. Preferably, the aerosol-generating substrate is a homogenized tobacco material.

Preferably, the homogenized tobacco material is in the form of a "cast sheet". The term "cast sheet" is used herein to denote a sheet article made by a casting process based on casting a pulp containing tobacco particles and a binder (e.g., guar gum) onto a support surface, such as a conveyor belt, drying the pulp and removing the dried sheet from the support surface. An example of a sheet casting or molding process is described, for example, in US-A-5,724,998 with respect to the manufacture of cast tobacco sheets. In the sheet casting process, particulate plant materials are mixed with a liquid component, typically water, to form a pulp. Other added components in the pulp may include fibers, a binder and an aerosol former. The particulate plant materials may agglomerate in the presence of a binder. The pulp is cast onto a support surface and dried to form a sheet of homogenized tobacco material.

In some preferred embodiments, the homogenized tobacco material used in the articles of the present invention is produced by molding. The homogenized tobacco material produced by the molding process typically comprises agglomerated particulate plant material.

The sheet casting process, since essentially all of the soluble fraction is retained in the plant material, provides the advantage of preserving most of the flavors. In addition, energy-intensive papermaking steps are eliminated.

In one preferred embodiment of the present invention, a mixture comprising particulate plant material, water, a binder and an aerosol former is prepared to produce a homogenized tobacco material. A sheet is prepared from said mixture, and then the sheet is dried. Preferably, said mixture is an aqueous mixture. As used herein, the term "dry weight" refers to the ratio of the weight of a particular non-aqueous component to the sum of the weights of all non-aqueous components in the mixture, expressed as a percentage. The composition of aqueous mixtures may be indicated in "percent dry weight." This refers to the ratio of the weight of the non-aqueous components to the weight of the entire aqueous mixture, expressed as a percentage.

The mixture may be a pulp. As used herein, the term "pulp" means a homogenized aqueous mixture with a relatively low dry weight. The pulp used in carrying out the method according to the present document may preferably have a dry weight of from about 5 percent to 60 percent.

Alternatively, the mixture may be a dough-like mass. As used herein, the term "dough-like mass" denotes an aqueous mixture with a relatively high dry weight. The dough-like mass used in carrying out the method according to the present document may preferably have a dry weight of at least 60 percent, more preferably at least 70 percent.

Pulps having a dry weight greater than 30 percent and pasty masses may be preferred in some embodiments of the method.

The step of mixing the particulate plant material, water and other optional components may be performed by any suitable means. In the case of low viscosity mixtures, i.e. some pulps, it is preferable that the mixing be performed using a high energy mixer or a high shear mixer. This mixing breaks up and evenly distributes the various phases of the mixture. For higher viscosity mixtures, i.e. some pasty masses, a kneading process may be used to evenly distribute the various phases of the mixture.

The methods according to the present invention may further comprise a step of vibrating the mixture to distribute the various components. Vibrating the mixture, i.e., for example, vibrating a container or intermediate bin in which the mixture to be homogenized is located, makes it possible to promote the homogenization of the mixture, in particular when the mixture is a low-viscosity mixture, i.e., in the case of some pulps. A shorter mixing time may be required to homogenize the mixture to the target value optimal for casting, if vibration is also applied together with mixing.

If the mixture is a pulp, the web of homogenized tobacco material is preferably obtained by a casting process comprising casting the pulp onto a support surface, such as a conveyor belt. The method for producing homogenized plant material includes the step of drying said cast web to form a sheet. The cast web may be dried at room temperature or at an ambient temperature of at least about 60 degrees Celsius, more preferably at least about 80 degrees Celsius, for a suitable period of time. Preferably, the cast web is dried at an ambient temperature of no more than 200 degrees Celsius, more preferably no more than about 160 degrees Celsius. For example, drying of the cast web is possible at a temperature of from about 60 degrees Celsius to about 200 degrees Celsius, or from about 80 degrees Celsius to about 160 degrees Celsius. Preferably, the moisture content of the sheet after drying is from about 5 percent to about 15 percent based on the total weight of the sheet. After drying, the sheet can be removed from the supporting surface. The cast sheet has such tensile strength that it can be moved by mechanical means and wound on or unwound from a roll without breaking or deforming.

If the mixture is a dough-like mass, the dough-like mass may be extruded to form a sheet, threads or strips before the step of drying the extruded mixture. Preferably, the dough-like mass may be extruded to form a sheet. The extruded mixture may be dried at room temperature or at a temperature of at least about 60 degrees Celsius, more preferably at least about 80 degrees Celsius, for a suitable period of time. Preferably, the extruded mixture is dried at an ambient temperature of no more than 200 degrees Celsius, more preferably no more than about 160 degrees Celsius. For example, drying the extruded mixture is possible at a temperature of from about 60 degrees Celsius to about 200 degrees Celsius, or from about 80 degrees Celsius to about 160 degrees Celsius. Preferably, the moisture content of the extruded mixture after drying is from about 5 percent to about 15 percent based on the total weight of the sheet. A sheet obtained from a dough-like mass requires a shorter drying time and/or lower drying temperatures due to the significantly lower water content compared to a web obtained from pulp. After drying the sheet, the method may optionally include the step of applying a nicotine salt, preferably together with an aerosol forming substance, to the sheet, as described in the disclosure of WO-A-2015/082652.

After drying the sheet, the methods according to the present invention may optionally include the step of cutting the sheet into threads, pieces or strips to obtain the aerosol-generating substrate described above. The threads, pieces or strips may be brought together using suitable means to obtain a rod of aerosol-generating substrate. In the obtained rod of aerosol-generating substrate, the threads, pieces or strips may be substantially aligned, for example, in the longitudinal direction of the rod. Alternatively, the threads, pieces or strips may be randomly oriented in the rod.

The methods according to the present invention may optionally further include the step of winding the sheet onto a roll after the drying step.

Alternatively, the homogenized tobacco material of the present invention may be produced by a papermaking process for producing sheets of homogenized plant material in the form of plant "paper". Plant paper refers to a reconstituted plant sheet obtained by a process in which the plant material is extracted with a solvent to obtain an extract of soluble plant compounds and an insoluble residue of fibrous plant material, and this extract is re-mixed with the insoluble residue. The extract may optionally be concentrated or further processed before being re-mixed with the insoluble residue. The insoluble residue may optionally be purified and mixed with additional plant fibers before being re-mixed with the extract. When performing the method of the present invention, the plant material will contain tobacco particles, optionally in combination with tobacco particles.

More specifically, the method for producing plant paper includes a first step in which plant material and water are mixed to form a dilute suspension. The dilute suspension contains mainly separated cellulose fibers. The suspension has a lower viscosity and a higher water content than the pulp obtained in the casting process. Said first step may include soaking, optionally in the presence of an alkali, such as sodium hydroxide, and, optionally, exposure to heat.

The method further comprises a second stage in which the suspension is separated into an insoluble portion containing an insoluble residue in the form of fibrous plant material and a liquid or aqueous extract containing soluble plant compounds. The water remaining in the insoluble residue in the form of fibrous plant material can be drained through a mesh acting as a sieve, so that a web of randomly interwoven fibres can be laid. Water can be further removed from this web by compression with rollers, sometimes with the help of suction or vacuum.

After the aqueous portion and water are removed, a sheet is formed from the insoluble residue. Preferably, a generally flat, uniform sheet of plant fibers is formed.

Preferably, the method further comprises the steps of concentrating the extract of soluble plant compounds that have been removed from the leaf and adding the concentrated extract to the leaf from the insoluble residue in the form of fibrous plant material to form a sheet of homogenized plant material. Alternatively or additionally, a soluble plant substance or a concentrated plant substance from another process can be added to the leaf. The extract or concentrated extract can be obtained from another variety of plant of the same species or from plants of other species.

This process, as described in US-A-3,860,012, was used with tobacco to make reconstituted tobacco products, also known as tobacco paper.

In some preferred embodiments, the homogenized tobacco material used in the articles of the present invention is obtained by a papermaking process as defined above. In such embodiments, the homogenized tobacco material is present in the form of tobacco paper.

Homogenized tobacco material produced by this process is called tobacco paper. Homogenized tobacco material produced by the papermaking process can be recognized by the presence of numerous fibers throughout the material, visible to the naked eye or with an optical microscope, especially when the paper is wetted with water. In contrast, homogenized tobacco material produced by the casting process contains fewer fibers than paper and tends to disintegrate to form a pulp when wetted.

Other known processes which can be used to produce homogenised tobacco materials are reconstitution processes of the type described, for example, in US-A-3,894,544; and extrusion processes of the type described, for example, in GB-A-983,928. Typically, the density values of homogenised tobacco materials produced by extrusion processes and reconstitution processes are higher than the density values of homogenised tobacco materials produced by casting processes.

Preferably, the aerosol-generating substrate of the aerosol-generating articles according to the present invention comprises at least about 200 mg of homogenized tobacco material, more preferably at least about 220 mg of homogenized tobacco material, more preferably at least about 250 mg of homogenized tobacco material.

Aerosol-generating articles according to the present invention comprise a rod containing homogenized tobacco material in one or more plugs. The rod of aerosol-generating substrate may have a length of from about 5 mm to about 120 mm. For example, the rod may preferably have a length of from about 10 mm to about 45 mm, more preferably from about 10 mm to 15 mm, most preferably about 12 mm. In alternative embodiments, the rod preferably has a length of from about 30 mm to about 45 mm, or from about 33 mm to about 41 mm. If the rod is formed by one plug of homogenized tobacco material, then this plug has the same length as the rod.

The aerosol-generating substrate rod may have an outer diameter of about 5 mm to about 10 mm, depending on its intended use. For example, in some embodiments, the rod may have an outer diameter of about 5.5 mm to about 8 mm, or about 6.5 mm to about 8 mm. The "outer diameter" of the aerosol-generating substrate rod corresponds to the diameter of the rod, including any wrappers.

The rod of the aerosol-generating substrate of the aerosol-generating articles according to the present invention is preferably surrounded by one or more wrappers along at least part of its length. The said one or more wrappers may include a paper wrapper and/or a non-paper wrapper. Paper wrappers suitable for use in specific embodiments of the present invention are known in the art and include, without limitation, cigarette paper of various types and filter wicks. Non-paper wrappers suitable for use in specific embodiments of the present invention are known in the art and include, without limitation, sheets of homogenized tobacco materials.

In particular embodiments of the present invention, the aerosol-generating substrate is surrounded along at least a portion of its length by a heat-conducting sheet material, such as a metal foil, such as aluminum foil or metallized paper. The metal foil or metallized paper serves the purpose of quickly conducting heat through the aerosol-generating substrate. In addition, the metal foil or metallized paper can serve to prevent the aerosol-generating substrate from igniting if the consumer attempts to set it on fire. In addition, during use, the metal foil or metallized paper is able to prevent unpleasant odors generated by heating the outer wrapper from penetrating into the aerosol generated from the aerosol-generating substrate. For example, this can be a problem in the case of aerosol-generating articles having an aerosol-generating substrate that is heated from the outside during use for the purpose of generating an aerosol. Alternatively or additionally, a metallized wrapper may be used to facilitate detection or recognition of the aerosol-generating article when it is inserted into the aerosol-generating device during use. The metal foil or metallized paper may contain metal particles, such as iron particles.

Said one or more wrappers surrounding the aerosol generating substrate preferably have a total thickness of from about 0.1 mm to about 0.9 mm.

The inner diameter of the aerosol-generating substrate rod is preferably from about 3 mm to about 9.5 mm, more preferably from about 4 mm to about 7.5 mm, more preferably from about 5 mm to about 7.5 mm. The "inner diameter" corresponds to the diameter of the aerosol-generating substrate rod without including the thickness of the wrappers, but measured with the wrappers in place.

Aerosol generating articles according to the present invention also include, without limitation, a cartridge or a disposable part for a hookah.

The aerosol-generating articles according to the present invention may optionally comprise at least one hollow tube located downstream of the aerosol-generating substrate in close proximity thereto. One of the functions of the tube is to position the aerosol-generating substrate near the distal end of the aerosol-generating article in such a way as to allow it to be brought into contact with the heating element. The tube functions in such a way that it prevents the aerosol-generating substrate from moving along the aerosol-generating article in the direction of other downstream elements when the heating element is inserted into the aerosol-generating substrate. The tube also functions as a separating element for separating the downstream elements from the aerosol-generating substrate. The tube may be made of any material, such as cellulose acetate, polymer, cardboard or paper.

The aerosol-generating articles according to the present invention optionally comprise one or more of a spacer or an aerosol-cooling element located downstream of the aerosol-generating substrate and downstream of the hollow tube in close proximity to it. In use, the aerosol formed by volatile compounds released from the aerosol-generating substrate passes through the aerosol-cooling element and is cooled by it before inhalation by the user. The lower temperature allows the vapors to condense to form an aerosol. The spacer or aerosol-cooling element may be a hollow tube, such as a hollow cellulose acetate tube or a cardboard tube, which may be similar to the tube located downstream of the aerosol-generating substrate in close proximity to it. The spacer may be a hollow tube with the same outer diameter, but with a smaller or larger inner diameter compared to the hollow cellulose acetate tube. In one embodiment, the paper-wrapped aerosol cooling element comprises one or more longitudinal channels and is made of any suitable material, such as metal foil, paper laminated with foil, a polymer sheet, preferably made of a synthetic polymer, and substantially non-porous paper or cardboard. In some embodiments, the paper-wrapped aerosol cooling element may comprise one or more sheets made of a material selected from the group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA), cellulose acetate (CA), paper laminated with a polymer sheet, and aluminum foil. Alternatively, the aerosol cooling element may be made of interwoven or non-interwoven threads of a material selected from the group consisting of polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polylactic acid (PLA) and cellulose acetate (CA). In a preferred embodiment, the aerosol cooling element is a corrugated and assembled sheet of polylactic acid wrapped in filter paper. In another preferred embodiment, the aerosol cooling element comprises a longitudinal channel, and it is made of interwoven threads of a synthetic polymer, such as threads of polylactic acid, which are wrapped in paper.

The aerosol-generating articles of the present invention may further comprise a filter or mouthpiece located downstream of the aerosol-generating substrate and a hollow acetate tube, spacer or aerosol cooling element. The filter may comprise one or more filter materials for removing particulate components, gaseous components or a combination thereof. Suitable filter materials are known in the art and include, but are not limited to: fibrous filter materials, such as, for example, cellulose acetate tow and paper; adsorbents, such as, for example, activated alumina, zeolites, molecular sieves and silica gel; biodegradable polymers, including, for example, polylactic acid (PLA), Mater-Bi®, hydrophobic viscose fibers and bioplastics; and combinations thereof. The filter may be located at the downstream end of the aerosol-generating article. The filter may be a cellulose acetate filter plug. The filter in one embodiment has a length of approximately 7 mm, however, it may have a length of from approximately 5 mm to approximately 10 mm.

The aerosol-generating articles according to the present invention may comprise a cavity at the mouth end, i.e. at the downstream end of the article. The cavity at the mouth end may be formed by one or more wrappers extending downstream of the filter or mouthpiece. Alternatively, the cavity at the mouth end may be formed by a separate tubular element provided at the downstream end of the aerosol-generating article.

Preferably, the aerosol-generating articles according to the present invention further comprise a ventilation zone provided at a location along the aerosol-generating article. For example, the aerosol-generating article may be provided at a location along a hollow tube located downstream of the aerosol-generating substrate.

In preferred embodiments of the present invention, the aerosol-generating article comprises an aerosol-generating substrate, at least one hollow tube located downstream of the aerosol-generating substrate, and a filter located downstream of said at least one hollow tube. If necessary, the aerosol-generating article further comprises a cavity at the mouth end, i.e. at the downstream end of the filter. Preferably, the ventilation zone is provided at a location along said at least one hollow tube.

The aerosol-generating articles according to the present invention may have a total length of at least about 30 mm or at least about 40 mm. The total length of the aerosol-generating article may be less than 90 mm or less than about 80 mm.

In one embodiment, the aerosol-generating article has a total length of about 40 mm to about 50 mm, preferably about 45 mm. In another embodiment, the aerosol-generating article has a total length of about 70 mm to about 90 mm, preferably about 80 mm to about 85 mm. In another embodiment, the aerosol-generating article has a total length of about 72 mm to about 76 mm, preferably about 74 mm.

The aerosol-generating article may have an outer diameter of about 5 mm to about 8 mm, preferably about 6 mm to about 8 mm. In one embodiment, the aerosol-generating article has an outer diameter of about 7.3 mm.

The aerosol-generating articles of the present invention may further comprise one or more aerosol-modifying elements. The aerosol-modifying element may provide an aerosol-modifying substance. As used herein, the term "aerosol-modifying substance" is used to describe any substance that, when used, modifies one or more features or properties of an aerosol passing through a filter. Suitable aerosol-modifying substances include, but are not limited to, substances that, when used, impart flavor or aroma to an aerosol passing through a filter, or substances that, when used, remove flavors from an aerosol passing through a filter.

The aerosol modifying agent may be one or more of moisture or a liquid flavoring agent. Water or moisture may modify the organoleptic sensations of the user, for example, by moistening the generated aerosol, which may have a cooling effect on the aerosol and reduce the sensation of astringency experienced by the user. The aerosol modifying element may be present in the form of a flavor/aroma delivery element designed to deliver one or more liquid flavoring agents. Alternatively, the liquid flavoring agent may be added directly to the homogenized plant material, for example by adding the flavoring agent to the pulp or raw material during the preparation of the homogenized plant material or by spraying the liquid flavoring agent onto the surface of the homogenized plant material.

Said one or more liquid flavoring substances may comprise any flavoring compound or plant extract suitable for placement in liquid form with the possibility of separation within the element for delivering flavor/aroma in order to improve the taste of the aerosol generated during use of the aerosol-generating article. Flavoring substances, liquid or solid, may also be located directly in the material that forms the filter, such as cellulose acetate tow. Suitable flavoring agents or aromas include, but are not limited to, menthol, mint such as peppermint and spearmint, chocolate, licorice, citrus and other fruit flavors, gamma-octalactone, vanillin, ethyl vanillin, breath fresheners, spicy flavors such as cinnamon, methyl salicylate, linalool, eugenol, bergamot oil, geranium oil, lemon oil, hemp oil, and tobacco flavor. Other suitable flavoring agents may include flavoring compounds selected from the group consisting of an acid, an alcohol, an ester, an aldehyde, a ketone, a pyrazine, combinations or mixtures thereof, and the like.

The aerosol modifying agent may be an adsorbent material such as activated carbon that removes certain components of the aerosol passing through the filter and thus modifies the taste and aroma of the aerosol.

Said one or more aerosol modification elements may be located downstream of the aerosol-generating substrate or inside the aerosol-generating substrate. The aerosol-generating substrate may comprise a homogenized tobacco material and an aerosol modification element. In various embodiments, the aerosol modification element may be located adjacent to the homogenized tobacco material or embedded in the homogenized tobacco material. Typically, the aerosol modification elements may be located downstream of the aerosol-generating substrate, most often inside an aerosol cooling element, inside a filter of the aerosol-generating article, for example, inside a filter plug or inside a cavity between filter plugs. Said one or more aerosol modification elements may be present in the form of one or more of a thread, a capsule, a microcapsule, a bead or a polymer matrix material, or a combination thereof.

If the aerosol modification element is present in the form of a thread, as described in WO-A-2011/060961, this thread can be made of paper, such as filter paper, and said thread can be loaded with at least one aerosol modification substance and located inside the filter body. Other materials that can be used to make the thread include acetyl cellulose and cotton.

If the aerosol modification element is present in the form of a capsule as described in WO-A-2007/010407, WO-A-2013/068100 and WO-A-2014/154887, this capsule may be a destructible capsule located inside the filter, wherein the inner core of said capsule contains an aerosol modification substance that is capable of being released when the outer shell of the capsule is destructed when the filter is subjected to an external force. The capsule may be located inside the filter plug or inside the cavity between the filter plugs.

If the aerosol modifying element is present in the form of a polymeric matrix material, the polymeric matrix material releases the flavoring substance when the aerosol generating article is heated, for example when the polymeric matrix is heated to a temperature exceeding the melting point of the polymeric matrix material, as described in WO-A-2013/034488. Typically, such a polymeric matrix material may be located within a bead located within the aerosol generating substrate. Alternatively or additionally, the flavoring substance may be contained within domains of the polymeric matrix material and is capable of being released from the polymeric matrix material when the polymeric matrix material is compressed. Preferably, the flavoring substance

is released when the polymeric matrix material is compressed with a force of approximately 15 newtons. Such taste/aroma modification elements are capable of providing a delayed release of the liquid flavoring substance in a force range of at least 5 newtons, such as from 5 N to 20 N, as described in WO2013/068304. Typically, such a polymeric matrix material may be located inside a ball located inside the filter.

The aerosol generating article may comprise a combustible heat source and an aerosol generating substrate located downstream of the combustible heat source, wherein the aerosol generating substrate is as described above in relation to the first aspect of the present invention.

For example, the substrates described herein may be used in heated aerosol-generating articles of the type disclosed in WO-A-2009/022232, which comprise a combustible carbon heat source, an aerosol-generating substrate located downstream of the combustible heat source, and a heat-conducting element surrounding a rear portion of the combustible carbon heat source and an adjacent front portion of the aerosol-generating substrate and in contact with these portions. However, it should be understood that the substrates described herein may also be used in heated aerosol-generating articles comprising combustible heat sources of a different design.

The present invention provides an aerosol generating system that comprises an aerosol generating device comprising a heating element and an aerosol generating article for use with the aerosol generating device, wherein the aerosol generating article comprises an aerosol generating substrate as described above.

In a preferred embodiment, the aerosol-generating substrates described herein can be used in heated aerosol-generating articles for use in electric aerosol-generating systems, in which the aerosol-generating substrate of the heated aerosol-generating article is heated using an electric heat source.

For example, the aerosol generating substrates described herein may be used in heated aerosol generating articles of the type disclosed in EP-A-0822760.

The heating element of such aerosol generating devices may be in any form suitable for conducting heat. Heating of the aerosol generating substrate may be performed from the inside and/or from the outside. The heating element may preferably be a heating blade or pin, designed to be inserted into the substrate so that the substrate is heated from the inside. Alternatively, the heating element may partially or completely surround the substrate and heat the substrate circumferentially from the outside.

In some embodiments of the present invention, the aerosol-generating system comprises an aerosol-generating article that comprises an aerosol-generating substrate as defined above, a source of an aerosol-forming substance, and means for evaporating the aerosol-forming substance, preferably a heating element as described above. The source of the aerosol-forming substance may be a reservoir that may be configured to be refillable or replaceable and is located on the aerosol-generating device. Although the reservoir is physically separated from the aerosol-generating article, the generated vapor is directed through the aerosol-generating article. The vapor comes into contact with the aerosol-generating substrate, which releases volatile compounds, such as nicotine and flavoring substances contained in the plant material, to form an aerosol. If necessary, to facilitate the evaporation of the compounds contained in the aerosol-generating substrate, the aerosol-generating system may further comprise a heating element for heating the aerosol-generating substrate, preferably in concert with the heating of the aerosol-forming substance. However, in some embodiments, the heating element used to heat the aerosol-generating article is separate from the heater that heats the substance to form the aerosol.

As defined above, the present invention further provides a method for producing dried green tobacco material for use in the aerosol-generating substrate of the present invention, as described in detail below. The method of the present invention includes the following steps: providing unaged green tobacco leaves; drying the unaged green tobacco leaves until a moisture content of from 4 percent by weight to 15 percent by weight is achieved; and cutting or grinding the unaged green tobacco leaves to obtain dried green tobacco material. According to the present invention, the temperature, pressure and duration of the drying step are selected such that the dried green tobacco material maintains a chlorophyll level of at least 0.5 milligrams per gram. This means that the drying step is carried out such that the chlorophyll level in the tobacco leaves is maintained and the leaves remain green. The green tobacco leaves are not subjected to a aging process.

Preferably, the drying step in the method according to the present invention is completed within 5 days after the collection of the unaged green tobacco leaves, more preferably within 4 days after the collection, more preferably within 3 days after the collection, and most preferably within 2 days after the collection. This means that the total time of storage and drying of the tobacco material does not exceed 5 days, or 4 days, or 3 days, or 2 days from the time of collection of the tobacco material. Therefore, the dried green tobacco material is obtained within a relatively short period of time after the collection of the tobacco, so that it is possible to minimize any impact on the chemical composition of the tobacco leaves as a result of the storage of the tobacco leaves.

The method of the present invention provides a fast and efficient way of processing green tobacco leaves into dried green tobacco material, which is suitable for use in an aerosol-generating substrate for an aerosol-generating article, as described above. This in turn allows for a more efficient production of the aerosol-generating substrate, both in terms of time and cost. The method of the present invention can be applied to all types of tobacco. The method of the present invention provides the advantage of being able to apply it to whole tobacco leaves, without removing the stalks, if necessary. Alternatively, the method according to the present invention can be applied to the lamina of unaged green tobacco leaves. In this case, the leaves will be subjected to the removal of stalks before the drying step, and the stalks will be processed separately. If necessary, the stalks can be re-mixed with the tobacco lamina to provide dried green tobacco material to produce an aerosol-generating substrate.

The drying of green tobacco leaves is carried out under specially selected conditions of temperature and pressure so that aging does not occur and the tobacco leaves retain their green color. As described above, the use of green tobacco leaves in an aerosol-generating substrate has a number of advantages based on the reduced levels of certain undesirable components that are present in green tobacco leaves compared to aged leaves.

A number of different methods are available for rapidly drying unaged tobacco leaves to reduce the moisture content to a level of from about 4 percent to about 15 percent by weight, more preferably from about 10 percent to about 13 percent by weight, while maintaining the highest possible levels of chlorophyll in the leaves. Depending on the method chosen, the temperature, pressure and duration are specifically tailored to ensure the desired result.

In some embodiments, the drying step is performed by heating unaged green tobacco leaves to reduce the moisture content of the leaves as quickly as possible. Heating the tobacco leaves can be accomplished using any suitable device, such as an oven or a dryer, which should be known to those skilled in the art. Preferably, heating the tobacco leaves is performed in a tray dryer. An example of a suitable device for performing the drying step is a tray dryer available from Wolvering Proctor & Schwartz Ltd.

In a tray dryer, the tobacco leaves are typically suspended within a heating chamber, which minimizes contact between leaves and maximizes the exposed surface area of the leaves to facilitate drying. During the drying stage, heated air or steam is circulated through the chamber at the desired temperature. It has been found that using a tray dryer to heat the tobacco leaves provides the advantage of uniformly heating the leaves while minimizing the number of hot spots within the dryer. This optimizes the uniformity of drying of the leaves. It has also been found that using a tray dryer is most effective for drying the midribs of tobacco leaves, which typically dry more slowly than the lamellar portions of the leaves.

Preferably, in such embodiments, the drying step is performed at a temperature of less than about 120 degrees Celsius, more preferably at a temperature of less than about 110 degrees Celsius. Preferably, the drying step is performed at a temperature of at least about 75 degrees Celsius, more preferably at least about 85 degrees Celsius, and more preferably at least about 100 degrees Celsius. For example, the drying step can be performed at a temperature of from about 75 degrees Celsius to about 120 degrees Celsius, or from about 75 degrees Celsius to about 110 degrees Celsius. This temperature level is selected to ensure efficient drying while maintaining a relatively high level of chlorophyll and preventing damage to the leaves during the heating process.

In a particularly preferred embodiment, the drying step is carried out at a temperature of from 75 degrees Celsius to 110 degrees Celsius in a tray dryer.

The duration of the heating step will depend on the moisture level of the unaged tobacco leaves before drying, as well as the specific temperature selected for the heating step and the precise heating conditions. Preferably, the tobacco leaves are heated for no more than 7 hours, preferably no more than 6 hours, preferably no more than 4 hours, more preferably no more than 2 hours, and most preferably no more than 1 hour.

In a particularly preferred example, the unaged tobacco leaves are heated at a temperature of 75 degrees Celsius for no more than 7 hours to achieve the desired reduction in moisture content. In an alternative preferred example, the unaged tobacco leaves are heated at a temperature of 110 degrees Celsius for no more than 4 hours to achieve the desired reduction in moisture content.

Preferably, the heating step is carried out under ventilated conditions, with a continuous flow of air or inert gas passing through the tobacco leaves during heating. This provides the advantage of being able to reduce the required drying time.

Preferably, the heating step is carried out without stirring the tobacco leaves, for example in a rotating drum. This prevents possible damage to the tobacco leaves during heating.

The heating step may be performed on whole, unmodified tobacco leaves. Alternatively, the tobacco leaves may be de-stemmed prior to the heating step so that the tobacco lamina and tobacco stalks are dried separately.

In some embodiments, the heating step includes heating whole tobacco leaves, separating the tobacco lamina from the tobacco stalks during drying, and removing the tobacco lamina from the dryer, followed by heating the remaining tobacco stalks until they are dry. This allows for efficient drying of both the tobacco lamina and midribs without overdrying the lamina.

In some embodiments, in which the drying step is performed by heating, the method according to the present invention may further include a second heating step, which is performed after the first heating step and at a lower temperature. For example, the method may further include a second heating step, during which the unaged green tobacco leaves are heated at a temperature of less than about 75 degrees Celsius or less than about 50 degrees Celsius. Inclusion of a second heating step may be advantageous in cases where the unaged tobacco leaves are left unchanged during drying, so that the tobacco stems (midribs) are allowed to dry completely.

As an alternative to heating, the drying step of the method of the present invention can be accomplished by lyophilization. Lyophilization, also known as freeze-drying, is a dehydration process that involves freezing a product (in this case, tobacco leaves) and then gradually reducing the pressure and increasing the temperature to sublimate the frozen water and thereby remove it from the product.

Preferably, during the drying of unaged green tobacco leaves by freeze-drying, the tobacco leaves are initially frozen to a temperature of less than minus 60 degrees, more preferably less than minus 75 degrees Celsius. For example, the tobacco leaves may be frozen to a temperature of approximately minus 80 degrees Celsius. Preferably, the freezing of the tobacco leaves is performed as soon as possible after the leaves are harvested.

The remaining steps of the lyophilization process are carried out in a suitable lyophilization chamber. In the first lyophilization step, the unaged tobacco leaves are preferably kept frozen at atmospheric pressure.

Preferably, the duration of the first lyophilization step is no more than about 60 minutes, more preferably no more than about 30 minutes.

In the second lyophilization stage, the vacuum degree and the temperature inside the chamber are gradually adjusted until the target pressure (which is lower than atmospheric pressure) and the target temperature (which is lower than room temperature) are reached. The target pressure is preferably about 0.1 mbar. The target temperature is preferably about 15 degrees Celsius. Preferably, the duration of the second lyophilization stage is from about 24 hours to about 60 hours.

In the third and final stage of lyophilization, the temperature is increased to approximately room temperature (22 degrees Celsius) under full vacuum. Preferably,

The duration of the third stage of lyophilization is from approximately 24 hours to approximately 60 hours.

As a further alternative, the drying step of the method of the present invention can be carried out using microwave heating. For example, unaged green tobacco leaves can be dried in a microwave tunnel dryer.

Using microwave heating to dry unaged green tobacco leaves allows for the moisture in the leaves to be removed very quickly because microwaves are able to quickly raise the temperature of the leaf, causing the water molecules within the tobacco to evaporate.

Preferably, during the drying step, the unaged green tobacco leaves are continuously moved through one or more microwave units, for example on a conveyor belt. The power and duration of the microwave heating step can be adapted to ensure the desired moisture level of the tobacco leaves.

Suitable microwave tunnel dryers are available in the market, such as those from Jinan Himax machinery Co., Ltd.

After drying the green tobacco leaves to the desired moisture content of 4 to 15 percent by weight, the dried tobacco leaves are processed to produce dried green tobacco material of the desired size. Unaged green tobacco leaves are preferably cut or shredded using known tobacco particle production techniques.

Specific embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

Fig. 1 shows a first embodiment of a substrate of an aerosol generating article described herein;

Fig. 2 shows an aerosol generating system that comprises an aerosol generating article and an aerosol generating device that comprises an electric heating element;

Fig. 3 shows an aerosol generating system that comprises an aerosol generating article and an aerosol generating device that comprises a combustible heating element;

Fig. 4 shows a sectional view of filter 1050, additionally containing an element for modifying the aerosol, wherein

Fig. 4a shows an element for modifying an aerosol in the form of a spherical capsule or ball inside a filter plug.

Fig. 4b shows an element for modifying the aerosol in the form of a thread inside the filter plug, and

Fig. 4c shows an element for modifying an aerosol in the form of a spherical capsule inside a cavity located inside the filter; and

Fig. 5 shows a sectional view of a plug made of aerosol generating substrate 1020, further comprising an elongated current collecting element.

Fig. 1 shows a heated aerosol-generating article 1000 comprising a substrate as described herein. The article 1000 comprises four elements; an aerosol-generating substrate 1020, a hollow cellulose acetate tube 1030, a separator element 1040, and a mouthpiece filter 1050. These four elements are arranged in series, aligned along one axis, and united by means of a cigarette paper 1060 to form the aerosol-generating article 1000. The article 1000 has a mouthpiece end 1012 that the user inserts into the mouth during use, and a distal end 1013 located at the opposite end of the article from the mouthpiece end 1012. The embodiment of the aerosol-generating article shown in Fig. 1, particularly suitable for use with an electric aerosol generating device comprising a heater for heating an aerosol generating substrate.

When assembled, the length of the 1000 product is approximately 4.5 millimeters, the outer diameter is approximately 7.2 millimeters, and the inner diameter is approximately 6.9 millimeters.

Aerosol generating substrate 1020 comprises a plug formed from a sheet of homogenized tobacco material containing a mixture of dried green tobacco material with aged tobacco particles.

A number of examples of homogenized tobacco material suitable for producing aerosol-generating substrate 1020 are shown in Table 1 below (see Samples A and B). The sheet is collected, pleated, and wrapped in filter paper (not shown) to form a plug. The sheet contains additives, including glycerin, as an aerosol forming agent.

The aerosol-generating article 1000 shown in Fig. 1 is configured to interact with an aerosol-generating device for the purpose of consuming it. Such an aerosol-generating device comprises means for heating an aerosol-generating substrate 1020 to a temperature sufficient for forming an aerosol. Typically, the aerosol-generating device may comprise a heating element that surrounds the aerosol-generating article 1000, being located adjacent to the aerosol-generating substrate 1020, or a heating element that is inserted into the aerosol-generating substrate 1020.

After the aerosol generating article is brought into interaction with the aerosol generating device, the user draws on the mouth end 1012 of the smoking article 1000, and the aerosol generating substrate 1020 is heated to a temperature of approximately 375 degrees Celsius. At this temperature, volatile compounds are released from the aerosol generating substrate 1020. These compounds condense to form an aerosol. The aerosol is drawn through the filter 1050 into the user's mouth.

Fig. 2 shows a portion of an electric aerosol-generating system 2000 that uses a heating blade 2100 to heat an aerosol-generating substrate 1020 of an aerosol-generating article 1000. The heating blade is mounted inside a chamber for receiving the aerosol-generating article in an electric aerosol-generating device 2010. The aerosol-generating device has a plurality of air holes 2050 that allow air to flow toward the aerosol-generating article 1000. The air flow is indicated by arrows in Fig. 2. The aerosol-generating device includes a power source and an electronic circuit that are not shown in Fig. 2. The aerosol-generating article 1000 of Fig. 2 is as described in connection with Fig. 1.

In an alternative configuration shown in Fig. 3, the aerosol generating system is shown with a combustible heating element. While the article 1000 of Fig. 1 is intended for use in cooperation with an aerosol generating device, the article 1001 of Fig. 3 comprises a combustible heat source 1080 that can be ignited and the heat of which can be transferred to the aerosol generating substrate 1020 to create an inhalable aerosol. The combustible heat source 80 is a carbon element that is located near the aerosol generating substrate at the distal end 13 of the rod 11. Elements that are substantially the same as the elements of Fig. 1 are designated by the same numbers.

Fig. 4 shows a sectional view of the filter 1050, which additionally contains an element for modifying the aerosol. In Fig. 4a, the filter 1050 additionally contains an element for modifying the aerosol in the form of a spherical capsule or ball 605.

In the embodiment of Fig. 4a, a capsule or bead 605 is embedded in a filter segment 601 and surrounded on all sides by a filter material 603. In this embodiment, the capsule comprises an outer shell and an inner core, wherein the inner core contains a liquid flavoring substance. The liquid flavoring substance is intended to impart flavor/aroma to the aerosol during use of an aerosol-generating article equipped with a filter. The capsule 605 releases at least a portion of the liquid flavoring substance when the filter is subjected to an external force, such as by being squeezed by a consumer. In the embodiment shown, the capsule is generally spherical, with a substantially continuous outer shell containing the liquid flavoring substance.

In the embodiment of Fig. 4b, the filter segment 601 comprises a plug of filter material 603 and a flavour-carrying central thread 607 which extends axially through the plug of filter material 603 parallel to the longitudinal axis of the filter 1050. The flavour-carrying central thread 607 has substantially the same length as the plug of filter material 603, as a result of which the ends of the flavour-carrying central thread 607 are visible at the ends of the filter segment 601. In Fig. 4b, the filter material 603 is an acetate cellulose tow. The flavour-carrying central thread 607 is obtained from a twisted filter filament and is loaded with an aerosol modifying substance.

In the embodiment of Fig. 4c, the filter segment 601 comprises more than one plug of filter material 603, 603'. Preferably, the plugs of filter material 603, 603' are made of acetyl cellulose, so that they are capable of filtering the aerosol generated by the aerosol-generating article. Around the filter plugs 603, 603', a wrapper 609 is wrapped connecting them. Inside the cavity 611, a capsule 605 is located, comprising an outer shell and an inner core, wherein the inner core contains a liquid flavoring substance. Otherwise, the capsule is similar to the embodiment of Fig. 4a.

Fig. 5 shows a sectional view of an aerosol-generating substrate 1020 further comprising an elongated current-collecting strip 7 05. The aerosol-generating substrate 1020 comprises a plug 703 formed from a sheet of homogenized tobacco material comprising a mixture of dried green tobacco material and aged tobacco particles. The elongated current-collecting strip 705 is embedded within the plug 703 and extends longitudinally between an upstream end and a downstream end of the plug 703. In use, the elongated current-collecting strip 705 heats the homogenized tobacco material by induction heating as described above.

Example

Various samples of homogenized tobacco material for use in the aerosol-generating substrate of the present invention, described above with reference to the figures, can be made from aqueous pulps having the compositions shown in Table 1. Samples A-D contained dried green tobacco material (either alone or mixed with aged tobacco particles) according to the present invention. Sample E contained aged tobacco particles only and is included for comparison purposes only.

Sample A was made with a carboxymethyl cellulose binder mixed with cellulose fibers according to a second preferred embodiment of the present invention. Sample A was made from an aqueous pulp containing 72.97 kg of water per 100 kg of pulp, with the remainder being the components in the relative amounts shown in Table 1.

Samples B-D were made with a guar gum binder according to the first preferred embodiment of the present invention. Samples B-D were made from an aqueous pulp containing 78-79 kg of water per 100 kg of pulp.

In the table below, "DWB" stands for "dry weight base", in this case the weight percentages calculated relative to the dry weight of the homogenized plant material. The tobacco particles were ground to an average particle size of 100 microns using a triple impact mill.

The dried green tobacco material was obtained from Burley tobacco leaves and was subjected to rapid drying using the heating method according to the present invention described above. The aged tobacco particles can be obtained from aged tobacco of one or more types, if necessary.

The pulps can be cast using a casting bar (0.6 mm) onto a glass plate, dried in an oven at 140 degrees Celsius for 7 minutes, and then dried in a second oven at 120 degrees Celsius for 30 seconds.

For each of the samples A-E of homogenized tobacco material, a plug can be made from a single continuous sheet of homogenized tobacco material, each of the sheets having a width of from 100 mm to 130 mm. The individual sheets preferably have a thickness of about 220 microns and a grammage of about 189 g/m ² . The cutting width of each sheet is about 120 mm. The sheets can be corrugated to a height of from 165 microns to 170 microns, rolled to form plugs having a length of about 12 mm and diameters of about 7 mm, and surrounded by a paper wrapper. The total weight of each plug is about 250 mg.

For each of the plugs, an aerosol generating article may be manufactured having an overall length of approximately 45 mm and a structure as shown in Fig. 3 and comprising, starting from the downstream end: a cellulose acetate filter (approximately 7 mm long) at the mouthpiece end, an aerosol divider comprising a pleated sheet of polylactic acid polymer (approximately 18 mm long), a hollow acetate tube (approximately 8 mm long) and a plug of aerosol generating substrate.

Comparative example 1 - Burley tobacco

To demonstrate the effect of the aging process on the chemical composition of Burley tobacco, the levels of certain tobacco constituents were measured for three samples of Burley tobacco leaf: unaged green Burley tobacco leaf, 5-day air-cured Burley tobacco leaf, and fully air-cured (50-day) Burley tobacco leaf. Each sample originally consisted of the same unaged green Burley tobacco leaf, and therefore it is assumed that the change in the levels of each constituent was a direct result of the aging process. The results are shown in Table 2 below:

As shown in the table, the chlorophyll level drops significantly to very low levels after only 5 days of aging. This demonstrates that having chlorophyll levels above 0.5 mg/g is a sure sign of unaged green tobacco leaves.

It was found that the levels of asparagine, ammonia, total free amino acids and N-nitrosonornicotine were significantly increased by the aging process, such that in each case the level of the component in the aged leaves was several times higher than in the unaged green leaves. As shown below, the reduced levels of these components in the unaged green tobacco leaves resulted in a reduction of the corresponding undesirable component in the aerosol generated from homogenized tobacco material containing unaged green tobacco.

Sugar levels in Burley tobacco leaves were found to range from 6.87 percent by weight for unaged green tobacco leaves to 6.47 percent by weight for 5-day aged tobacco leaves and to 1.7 percent by weight for fully aged tobacco leaves when measured on a dry weight basis.

For each of the Burley samples, using the casting process described above, a homogenized tobacco material was obtained having the composition shown in Table 3 below:

Each of the homogenized tobacco material samples was assembled to form a rod of aerosol-generating substrate weighing 250 mg, which was then incorporated into an aerosol-generating article as described in the example above. Each of these aerosol-generating articles was used to generate and collect inhalable aerosol according to test method A described above. Aerosol was captured and analyzed for each sample.

As detailed above, under test method A, aerosol-generating products may be tested using a commercially available holder (THS2.2 holder) of the Tobacco Heating System 2.2 of the IQOS® Heat Without Combustion device from Philip Morris Products SA. The aerosol-generating products were heated in a Health Canada-specified machine smoking mode for 30 puffs using a puff volume of 55 ml, a puff duration of 2 seconds and an inter-puff interval of 30 seconds (as described in ISO/TR 19 4 7 8-1:2014). The aerosol generated during this smoking test was collected on a Cambridge filter pad and extracted using a liquid solvent.

Table 4 below shows the levels of several tobacco-derived aerosol constituents in aerosols produced from three samples containing unaged green Burley tobacco particles, 5-day aged Burley tobacco particles, and fully aged Burley tobacco particles. The amounts of each aerosol constituent are expressed per unit, based on a rod weight of 250 mg of aerosol-generating substrate:

The results shown in Table 4 demonstrate the effect of including a proportion of dried green tobacco material in the homogenized tobacco material forming the aerosol-generating substrate on the levels of aerosol components.

Notably, the acrylamide level in the aerosol obtained from the sample containing dried green tobacco material was significantly lower than the other two samples containing only aged tobacco particles. This is believed to be due to the lower levels of asparagine in unaged tobacco leaves, as described above. The levels of ammonia, hydrogen sulfide, and methanethiol in the aerosol obtained from the sample containing dried green tobacco material were also significantly lower than the other two samples containing only aged tobacco particles.

These results demonstrate the beneficial effect that the aging process does not significantly affect the nicotine released from the tobacco material into the aerosol, and thus the use of dried green tobacco material instead of aged tobacco particles does not affect the nicotine content of the aerosol.

Overall, the aerosol produced from the sample containing dried green tobacco material demonstrated reduced levels of some undesirable compounds while maintaining stable nicotine delivery.

Similar reductions in these aerosol components can also be expected from other types of tobacco, such as Virginia.

Claims (22)

1. An aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the aerosol-generating substrate comprises homogenized tobacco material that contains from 10 to 50 percent by weight of dried green tobacco material on a dry weight basis, aged tobacco material or aerosol-generating plant material, an aerosol-forming substance, and an exogenous binder, wherein the homogenized tobacco material has an aerosol-forming substance content of from 5 to 55 percent by weight on a dry weight basis. 2. An aerosol generating article according to claim 1, wherein the homogenized tobacco material comprises at least one of: at least 0.1 milligrams of chlorophyll per gram on a dry weight basis; and not more than 2.5 milligrams of asparagine per gram on a dry weight basis. 3. An aerosol-generating article according to claim 1 or 2, wherein the homogenized tobacco material further comprises at least 1 percent by weight of aged tobacco material, calculated on a dry weight basis. 4. The aerosol-generating article of claim 3, wherein the ratio of dried green tobacco material to aged tobacco material in the homogenized tobacco material is no more than 1:1. 5. An aerosol-generating article according to any of the preceding claims, wherein the homogenized tobacco material contains from 1 to 10 percent by weight of a binder, calculated on a dry weight basis. 6. An aerosol generating article according to any of the preceding claims, wherein the homogenized tobacco material is present in the form of a cast sheet. 7. An aerosol-generating article according to any of the preceding claims, wherein the aerosol-generating plant material is obtained from one or more plants selected from: hemp, tea, ginger, eucalyptus, cloves, mint, anise, rosemary, chamomile, thyme and dill seeds. 8. An aerosol-generating article according to any of the preceding claims, wherein the dried green tobacco material has a moisture content of from 10 to 13 percent by weight. 9. An aerosol-generating article according to any one of the preceding claims, wherein the dried green tobacco material is obtained from tobacco leaf blades, tobacco stalks, or a combination thereof. 10. An aerosol-generating article according to any one of the preceding claims, wherein the dried green tobacco material is in the form of dried green tobacco particles. 11. An aerosol-generating article according to any one of the preceding claims, wherein the homogenized tobacco material further comprises at least 3 percent by weight of cellulose fibers. 12. An aerosol-generating article according to any one of the preceding claims, wherein the rod of the aerosol-generating substrate comprises one or more sheets of homogenized tobacco material. 13. The aerosol generating article of claim 12, wherein one or more sheets of homogenized tobacco material are collected and corrugated. 14. An aerosol generating system comprising: an aerosol generating device comprising a heating element; and an aerosol generating article according to any of the preceding paragraphs. 15. A method for producing homogenized tobacco material for use in an aerosol-generating substrate of an aerosol-generating article according to any one of paragraphs 1-13, wherein the method comprises the following steps: mixing dried green tobacco material, aged tobacco material or aerosol-generating plant material, an aerosol forming agent, an exogenous binder and water to form a pulp; casting the pulp onto the surface to form a sheet of homogenized tobacco material; and drying a sheet of homogenized tobacco material, wherein the sheet of homogenized tobacco material has an aerosol forming substance content of from 5 to 55 percent by weight on a dry weight basis.