WO2025229040A1

WO2025229040A1 - Substrate for reducing harshness perception

Info

Publication number: WO2025229040A1
Application number: PCT/EP2025/061789
Authority: WO
Inventors: Felix FRAUENDORFER; Igor Alexandrovich KOLTYGA; Piotr JAROS
Original assignee: Philip Morris Products SA
Current assignee: Philip Morris Products SA
Priority date: 2024-05-01
Filing date: 2025-04-29
Publication date: 2025-11-06
Anticipated expiration: 2026-11-01

Abstract

An aerosol-generating substrate for use in an aerosol-generating system, the aerosol-generating substrate comprising: a cut filler comprising shredded plant material, an aerosol former, and a harshness-reduction agent, wherein the harshness-reduction agent consists of a carboxylic acid, wherein the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius.

Description

SUBSTRATE FOR REDUCING HARSHNESS PERCEPTION

The invention relates to an aerosol-generating substrate and to an aerosol-generating article comprising the aerosol-generating substrate. The invention also relates to a method of manufacturing the aerosol-generating substrate. The invention further relates to an aerosolgenerating system comprising the aerosol-generating article.

Heated-aerosol-generating articles in which an aerosol-generating substrate, such as a substrate containing a shredded plant-material and an aerosol-former, is heated in order to form an aerosol rather than combusted to form smoke, are known in the art. An aim of such ‘heated’ aerosol-generating articles is to reduce known harmful smoke constituents of the type produced by the combustion and pyrolytic degradation of tobacco in conventional cigarettes.

Typically in heated aerosol-generating articles, an aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-generating substrate. In use, volatile compounds are released from the aerosol-generating substrate by heat transfer to the aerosolgenerating substrate from the heat source and entrained in air drawn through the aerosolgenerating article. As the released compounds cool, they condense to form an aerosol that is inhaled by the user.

A number of aerosol-generating systems comprising handheld aerosol-generating devices configured to heat aerosol-generating substrates of heated aerosol-generating articles are known in the art. These include electrically-operated aerosol-generating devices in which an aerosol is generated by the transfer of heat from one or more electrical heating elements of the aerosolgenerating device to the aerosol-generating substrate of the heated aerosol-generating article. Known handheld electrically operated aerosol-generating devices typically comprise a battery, control electronics and one or more electrical heating elements for heating the aerosol-generating substrate of a heated aerosol-generating article designed specifically for use with the aerosolgenerating device.

Some known electrically-operated aerosol-generating devices comprise an internal heating element that is configured to be inserted into the aerosol-generating substrate of a heated aerosol-generating article. For example, WO 2013/098410 A2 discloses an aerosol-generating system comprising an aerosol-generating article and an electrically-operated aerosol-generating device comprising a heating element in the form of a blade that is inserted into the aerosolgenerating substrate of the aerosol-generating article.

Other known electrically-operated aerosol-generating devices comprise one or more external heating elements. For example, WO 2020/115151 A1 discloses an aerosol-generating system comprising an aerosol-generating article and an electrically-operated aerosol-generating device comprising an external heating element that circumscribes the outer periphery of the aerosol-generating article.

Electrically-operated aerosol-generating devices comprising an inductor configured to inductively heat aerosol-generating substrates of heated aerosol-generating articles are also known in the art. For example, WO 2015/176898 A1 discloses an aerosol-generating system comprising an aerosol-generating article comprising an elongate susceptor in thermal contact with the aerosol-generating substrate and an electrically-operated aerosol-generating device having an inductor for heating the aerosol-generating substrate. In use, the fluctuating or alternating electromagnetic field produced by the inductor induces eddy currents in the susceptor, causing the susceptor to heat up as a result of one or both of resistive losses (Joule heating) and, where the susceptor is magnetic, hysteresis losses. Heat generated in the susceptor is transferred to the aerosol-generating substrate by conduction.

In heated aerosol-generating systems for delivering nicotine to a user, pulmonary delivery of the inhalable aerosol generated from the heated aerosol-generating substrate is important for user palatability and satisfaction. Nicotine adsorption through the pulmonary alveoli is rapid and efficient. By contrast, nicotine adsorption in the upper airways is slower and less efficient. Nicotine adsorption in the upper airways may also undesirably be perceived by a user as having a sensorial harshness and induce mouth and throat irritation.

It is important in the field of heated aerosol-generating articles, and also in the field of combustible aerosol-generating articles, to minimise discomfort to the user as much as possible.

It is known in the art to provide an aerosol-generating article comprising a filter element. The filter element comprises a filtration material which is typically cellulose acetate tow. However, there is a need in the art to replace components, including filter elements, made from cellulose acetate with a more sustainable material. Paper is widely used in many applications, including filtration. However, it has been found that the use of paper as a filtration material in aerosolgenerating articles, for example, heat-not-burn products and combustible cigarettes, can give a sensation of sensorial harshness, which is undesirable.

The present invention relates to an aerosol-generating substrate for use in an aerosolgenerating system. The aerosol-generating substrate may comprise a cut filler. The cut filler may comprise a shredded plant-material. The aerosol-generating substrate may comprise an aerosol former. The aerosol-generating substrate may comprise a harshness-reduction agent. The harshness reduction agent may consist of a carboxylic acid. The carboxylic acid may have a vapor pressure of from 0.001 to 1 .00 Torr at 25 degrees Celsius.

According to a first aspect of the invention, provided is an aerosol-generating substrate for use in an aerosol-generating system, the aerosol-generating substrate comprising: a cut filler comprising shredded plant-material, an aerosol former, and a harshness-reduction agent, wherein the harshness-reduction agent consists of a carboxylic acid, wherein the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius.

Advantageously, the present inventors have found that the volatility of the harshnessreduction agent is sufficiently low, such that loss of the harshness-reduction agent during manufacturing and processing of the aerosol-generating substrate, and in the aerosol-generating substrate and aerosol-generating article, is mitigated. The harshness-reduction agent consisting of a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius may therefore be included directly in the aerosol-generating substrate. For example, the harshnessreduction agent does not need to be immobilised in a compound for its inclusion in the aerosolgenerating substrate. For instance, the harshness-reduction agent does not need to be included in the substrate as a less volatile compound which degrades to the target carboxylic acid used for protonation of nicotine.

Advantageously, it has been found that the harshness-reduction agent has a volatility that is sufficiently high, such that the harshness-reduction agent is readily released into the inhalable aerosol generated upon heating of the aerosol-generating substrate. Advantageously, the harshness reduction agent may therefore readily protonate nicotine contained in the inhalable aerosol.

Advantageously, the present inventors have found that an aerosol-generating substrate according to the first aspect has an improved transfer yield of the harshness-reduction agent from the substrate to the aerosol, for example, compared to aerosol-generating substrates known in the art.

Advantageously, the present inventors have found that an aerosol-generating substrate comprising a harshness-reduction agent according to the first aspect can enable the generation of an inhalable aerosol that may exhibit reduced perceived sensorial harshness and mouth and throat irritation, compared to known aerosol-generating substrates in the art.

Without wishing to be bound by theory, interaction between the sufficiently volatile carboxylic acid and nicotine contained in the inhalable aerosol generated by heating the aerosolgenerating substrate according to the first aspect, results in, at least some, for example, a majority, of the nicotine contained in the aerosol being protonated. Unprotonated nicotine exists in the gaseous phase of the aerosol. In contrast, protonated nicotine exists in the liquid phase or particulate phase of the aerosol. It has been found that increasing the proportion of protonated nicotine in the aerosol advantageously reduces perceived sensorial harshness and throat and mouth irritation. It has advantageously been found by the present inventors that a substrate according to the first aspect can increase the proportion of protonated nicotine in the liquid phase and/or particulate phase of the inhalable aerosol, and thus reduce the proportion of unprotonated nicotine in the gas phase of the inhalable aerosol. Therefore, it has advantageously been found that inclusion of the harshness-reduction agent consisting of a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius in the aerosol-generating substrate can reduce, at least partially, perceived sensorial harshness and throat and mouth irritation.

Advantageously, it has been found that the aerosol-generating substrate according to the first aspect of the invention may enable generation of an inhalable aerosol that provides adequate nicotine delivery to a user. The aerosol-generating substrate according to the first aspect of the invention therefore does not compromise nicotine delivery to a user when perceived harshness and throat and mouth irritation are, at least partially, reduced.

Advantageously, it has been found that the harshness-reduction agent is stable in the aerosol-generating substrate, for example, at ambient temperatures and pressures (e.g. at 25 degrees Celsius and 1 atmosphere, respectively). For example, the harshness-reduction agent does not degrade to its degradation products in the aerosol-generating substrate and before use of the heat-not-burn product to any appreciable degree, at ambient temperatures and pressures.

Advantageously, the harshness-reduction agent, and its degradation products, have been shown to exhibit a satisfactory toxicological profile at a preliminary assessment, and thus may be suitable for use in a heated aerosol-generating article, intended to be used by a user.

Advantageously, it has been found that the use of cut filler comprising a shredded plant material minimises the processing of the plant material that is required during the production of the aerosol-generating substrate. For example the use of cut filler comprising a shredded plant material minimises the amount of water required for the production of the aerosol-generating substrate and also minimises the required drying time compared to processes for producing other aerosol-generating substrates which use plant material in a different form, such as a reconstituted form. The production of the aerosol-generating substrate according to the invention can therefore be carried out in an energy and cost efficient manner.

In some examples, the carboxylic acid preferably has a vapor pressure of from 0.005 to 0.95 Torr at 25 degrees Celsius, for example of from 0.01 to 0.90 Torr at 25 degrees Celsius, for example of from 0.012 to 0.85 Torr at 25 degrees Celsius.

It has advantageously been found that a harshness-reduction agent consisting of a carboxylic acid having a vapor pressure within the aforementioned ranges may be readily transferred from the substrate to the aerosol, and increase nicotine protonation in the aerosol, which may result in a reduction in perceived sensorial harshness and mouth and throat irritation.

The volatility of the harshness-reduction agent consisting of a carboxylic acid having a vapor pressure within the aforementioned ranges may also be sufficiently low such that loss of the carboxylic acid e.g. during processing of the aerosol-generating substrate, may be mitigated.

The vapor pressure of the carboxylic acid may be measured using the method set out in ASTM E1194-17. Preferably, the vapor pressure of the carboxylic acid is measured at three temperature values. Preferably, the vapor pressure is measured at 15 degrees Celsius, 25 degrees Celsius, and 35 degrees Celsius.

In some examples, the pK_a of the carboxylic acid may be of from 3.20 to 5.50 in water at 25 degrees Celsius, for example of from 3.25 to 5.30 in water at 25 degrees Celsius, for example of from 3.30 to 5.20 in water at 25 degrees Celsius, for example of from 3.35 to 5.15 in water at 25 degrees Celsius, for example of from 3.40 to 4.50 in water at 25 degrees Celsius. Advantageously, it has been found that a harshness-reduction agent consisting of a carboxylic acid having a pK_a value within the aforementioned ranges can readily protonate nicotine in an aerosol, which can mitigate sensorial harshness and mouth and throat irritation.

In examples, the boiling point of the carboxylic acid may be of from 150 to 310 degrees Celsius, for example of from 160 to 270 degrees Celsius, for example of from 170 to 260 degrees Celsius, and for example of from 180 to 255 degrees Celsius.

Advantageously, the harshness-reduction agent consisting of a carboxylic acid having a boiling point within these ranges has a volatility such that the carboxylic acid can be readily transferred from the substrate to the aerosol generated by the aerosol-generating substrate at temperatures which are typically used for aerosol-generating articles.

Typically, the carboxylic acid does not decompose at or before its boiling point. Advantageously, the carboxylic acid does not degrade or decompose before it is transferred from the substrate to the aerosol, where it can protonate nicotine contained in the aerosol generated by the aerosol-generating substrate.

In some examples, the aerosol-generating substrate is preferably stable to thermal decarboxylation at temperatures of less than or equal to 300 degrees Celsius. For example, the harshness-reduction agent consisting of a carboxylic acid does not decarboxylate at temperatures of less than or equal 300 degrees Celsius. Said another way, the harshness-reduction agent consisting of a carboxylic acid is preferably not capable of undergoing thermal decarboxylation at a temperature of less than or equal to 300 degrees Celsius.

Preferably, the carboxylic acid is a monocarboxylic acid.

Preferably, the carboxylic acid is an aliphatic carboxylic acid.

Typically, the carboxylic acid has a chain length of from 3 to 8 carbon atoms.

In some examples, the carboxylic acid is selected from lactic acid, levulinic acid, succinic acid, crotonic acid, sorbic acid, trans-2-hexenoic acid, 3-hexenoic acid, 2-ethylbutyric acid, hexanoic acid, benzoic acid, 5-methyl-2-fuoric acid and cyclohexanecarboxylic acid.

The vapor pressure values of the above-mentioned carboxylic acids have been found to be the following:

In some examples, the aerosol-generating substrate comprises a cut filler comprising shredded plant material, an aerosol former, and a harshness-reduction agent, wherein the harshness-reduction agent consists of a carboxylic acid, wherein the carboxylic acid comprises a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius and/or the carboxylic acid is selected from lactic acid, levulinic acid, succinic acid, crotonic acid, sorbic acid, trans-2-hexenoic acid, 3-hexenoic acid, 2-ethylbutyric acid, hexanoic acid, benzoic acid, 5-methyl-2-fuoric acid and cyclohexanecarboxylic acid.

In some examples, the carboxylic acid is preferably lactic acid, levulinic acid or crotonic acid.

Typically, the carboxylic acid is an alpha-hydroxy carboxylic acid.

In some particularly preferred examples, the carboxylic acid is lactic acid.

Typically, the carboxylic acid is configured to directly protonate nicotine in an aerosol generated by heating the aerosol-generating substrate. For example, the carboxylic acid does not decompose or decarboxylate before protonating nicotine contained in an aerosol generated by heating the aerosol-generating substrate. Advantageously, the carboxylic acid does not need to be immobilised in another compound (e.g. as a less volatile compound) in the aerosol-generating substrate to protonate nicotine contained in an aerosol generated by heating the aerosolgenerating substrate.

Typically, the carboxylic acid is present at 0.1 to 10 weight percent on a dry weight basis. For example, the carboxylic acid may be present at 0.5 to 7.5 weight percent on a dry weight basis, preferably of from 0.75 to 5 weight percent on a dry weight basis, preferably of from 1.0 to 3 weight percent on a dry weight basis, more preferably of from 2.0 to 3.0 weight percent on a dry weight basis, and even more preferably of from 2.0 to 2.5 weight percent on a dry weight basis.

In some examples, the substrate preferably comprises a single harshness-reduction agent. For example, the substrate preferably comprises one harshness-reduction agent which consists of a carboxylic acid as described above.

For example, the harshness-reduction agent is preferably the only source of carboxylic acid in the substrate.

In particularly preferred examples, the aerosol-generating substrate does not comprise a geminal dicarboxylic acid. Preferably, the substrate is a solid aerosol-generating substrate. Advantageously, the solid form of the substrate facilitates the handling of the aerosol-generating substrate during manufacture of an aerosol-generating article, compared to, for example, aerosol-generating substrates in the form of a liquid.

In some examples, the shredded plant-material comprises tobacco material. For example, the shredded plant material may comprise shredded tobacco material.

For example, the tobacco material may include tobacco material from one or more of Bright tobacco, dark tobacco, aromatic tobacco and filler tobacco.

In some examples of the invention, the shredded plant material consists of tobacco material. For example, the shredded plant-material may consist of shredded tobacco material.

In examples of the invention, the tobacco material may comprise one or more of tobacco lamina, tobacco rib, tobacco stem and tobacco stalk.

In some examples of the invention, the tobacco material may consist of tobacco lamina, tobacco rib, tobacco stem or tobacco stalk.

In some examples, the shredded plant material which comprises tobacco material may further comprise an additive. The additive may be homogenously distributed throughout the shredded plant material comprising tobacco material. For example, the additive may be a nontobacco plant material, e.g. a shredded non-tobacco plant material, such as that described further below.

In some examples, the shredded plant material comprises a non-tobacco plant material. For example, the shredded plant material may comprise a shredded non-tobacco plant material.

In some examples, the non-tobacco plant material is present in addition to tobacco material.

In other examples, the non-tobacco plant material is an alternative to tobacco material in the cut filler. For example, the shredded plant material may comprise, or be substantially comprised of, a non-tobacco plant material. In such a case, the cut filler may be substantially free from tobacco material, such that the aerosol-generating substrate may be considered to be a tobacco- free aerosol-generating substrate.

In some examples, the shredded plant material consists of a non-tobacco plant material. For example, the shredded plant material consists of a shredded non-tobacco plant material.

The non-tobacco plant material may comprise or consist of one or more of non-tobacco plant leaf lamina, stems, seeds, root, bark, flower and fragments of ribs.

For example, the non-tobacco plant material may comprise or consist of one or more of: tea, coffee, star anise, lavender, clove, peppermint, chamomile, rosemary, eucalyptus, ginger, dill seed, thyme, oregano and cumin. Preferably, the non-tobacco plant material comprises or consists of clove. The non-tobacco plant material may advantageously improve the organoleptic properties of the aerosol-generating substrate. Preferably, the cut filler comprises at least 25 percent of plant leaf lamina, more preferably, at least 50 percent of plant leaf lamina, still more preferably at least 75 percent of plant leaf lamina and most preferably at least 90 percent of plant leaf lamina.

For example, the cut filler may comprise at least 25 percent of shredded tobacco lamina, more preferably, at least 50 percent of shredded tobacco lamina, still more preferably at least 75 percent of shredded tobacco lamina and most preferably at least 90 percent of shredded tobacco lamina.

In other examples, the cut filler may comprise at least 25 percent of non-tobacco plant leaf lamina, more preferably, at least 50 percent of non-tobacco plant leaf lamina, still more preferably at least 75 percent of non-tobacco plant leaf lamina and most preferably at least 90 percent of non-tobacco plant leaf lamina.

In examples, the substrate comprises nicotine.

For example, the substrate may comprise exogenous nicotine. The term “exogenous nicotine” refers to nicotine that is added to the aerosol-generating substrate as a distinct component, and distinct from any nicotine that is intrinsically present in the shredded plant material, for example, where the shredded plant material comprises shredded tobacco material.

Preferably, in examples where the shredded plant material comprises a non-tobacco plant material, exogenous nicotine is added to the aerosol-generating substrate.

In other examples, where the shredded plant material comprises or consists of a tobacco plant material, the substrate may comprise only intrinsic nicotine. In some examples, the aerosolgenerating substrate may comprise exogenous and intrinsic nicotine.

The total nicotine content of the aerosol-generating substrate is preferably of from 0.5 percent by weight to 5 percent by weight on a dry weight basis, preferably of from 1 percent by weight to 4 percent by weight, on a dry weight basis, and more preferably of from 1 .5 percent by weight to 3 percent by weight, on a dry weight basis. The total nicotine content corresponds to the total combined amount of intrinsic nicotine and exogenous nicotine present in the aerosol-generating substrate.

For example, the total nicotine content may refer to the total amount of only intrinsic nicotine that is present in the aerosol-generating substrate (e.g. where the example comprises cut filler comprising or consisting of shredded tobacco material).

In other examples, the total nicotine content may refer to the total amount of only exogenous nicotine present in the aerosol-generating substrate (e.g. in examples comprising cut filler which comprises or consists of non-tobacco plant material).

In other examples, the total nicotine content may refer to the total amount of intrinsic nicotine and exogenous nicotine (e.g. in examples comprising cut filler comprising shredded tobacco material and additional exogenous nicotine).

Typically, the aerosol-generating substrate preferably comprises of from 40 to 98 weight percent of the cut filler on a dry weight basis, preferably of from 50 to 95 weight percent of the cut filler on a dry weight basis, preferably of from 60 to 90 weight percent of the cut filler on a dry weight basis, and more preferably of from 70 to 85 weight percent of the cut filler. In some examples, the aerosol-generating substrate comprises around 82 weight percent of the cut filler, on a dry weight basis.

Preferably, the cut filler comprises other after-cut, filler tobacco or casing.

The aerosol-generating substrate comprises an aerosol former. The aerosol former may be any suitable known compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol. Suitable aerosol formers are for example: polyhydric alcohols such as, for example, triethylene glycol, 1 ,3-butanediol, propylene glycol and glycerine; esters of polyhydric alcohols such as, for example, glycerol mono-, di- or triacetate; aliphatic esters of mono-, di- or polycarboxylic acids such as, for example, dimethyl dodecanedioate and dimethyl tetradecanedioate; and combinations thereof.

In some examples, the aerosol former may comprise or consist of propylene glycol, triethylene glycol, 1 ,3-butanediol, glycerine, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate, and dimethyl tetradecanedioate. Preferably, the aerosol former comprises propylene glycol, glycerine, or a mixture of propylene glycol and glycerine.

Typically, the aerosol-generating substrate may comprise the aerosol former in at least 10 percent by weight, on a dry weight basis. Preferably, the aerosol-generating substrate comprises at least 12 percent by weight of aerosol former, and more preferably at least 15 percent by weight of aerosol former, on a dry weight basis.

Preferably, the aerosol-generating substrate comprises less than or equal to 40 percent by weight of aerosol former, more preferably less than or equal to 30 percent by weight of aerosol former, more preferably less than or equal to 25 percent by weight of aerosol former, more preferably less than or equal to 20 percent by weight, on a dry weight basis.

For example, the aerosol-generating substrate may comprise between 10 percent and 40 percent by weight of aerosol former, or between 12 percent and 30 percent by weight of aerosol former, or between 15 percent and 25 percent by weight of aerosol former, or between 15 percent and 20 percent by weight of aerosol former, on a dry weight basis. In some examples, the aerosolgenerating substrate comprises around 18 percent by weight of aerosol former.

Preferably, the shredded plant material is soaked with aerosol former. Soaking the shredded plant material can be done by spraying or by other suitable application methods.

Preferably, the shredded-plant material is impregnated with aerosol-former.

In some examples, the aerosol former may be applied to the plant material during the process of producing the cut filler (e.g. during a conditioning step).

In some examples, the aerosol former may be provided as a coating on a surface of the shredded-plant material. The aerosol former may also penetrate the plant material to an extent.

In some examples, the substrate comprises a flavourant. For example, the flavourant may comprise or consist of one or more of menthol, peppermint oil, gamma octalactone, vanillin, ethyl vanillin, methyl salicylate, linalool, bergamot oil, geranium oil, ginger oil, and lemon oil.

In examples where the shredded plant material comprises or consists of tobacco material, the shredded plant material has an average cut width of at least 0.75 millimetres. Preferably, the shredded plant material comprising or consisting of tobacco material has an average cut width of at least 0.8 millimetres, more preferably at least 0.85 millimetres, more preferably at least 0.9 millimetres.

Preferably, in examples where the shredded plant material forming the cut filler comprises or consists of tobacco material, the shredded plant material has an average cut width of less than or equal to 2 millimetres, more preferably less than or equal to 1.75 millimetres, more preferably less than or equal to 1.5 millimetres, more preferably less than or equal to 1.25 millimetres.

For example, the shredded plant material comprising or consisting of tobacco material may have an average cut width of between 0.75 millimetres and 2 millimetres, or between 0.8 millimetres and 1.75 millimetres, or between 0.85 millimetres and 1.5 millimetres, or between 0.9 millimetres and 1.25 millimetres. In one preferred embodiment, the shredded plant material has an average cut width of approximately 1 millimetre.

In examples where the shredded plant material comprises or consists of non-tobacco plant material, the shredded plant material may have a cut width of between 0.1 millimetres to 0.5 millimetres. The shredded plant material comprising or consisting of non-tobacco plant material having a cut width of between 0.1 millimetres to 0.5 millimetres is beneficial for manufacturing purposes and for the homogeneity of the aerosol-generating substrate. At cut widths above 0.5 millimetres, manufacturing becomes more challenging and the homogeneity of the shredded plant material in the aerosol-generating substrate decreases.

In some preferred embodiments, the shredded plant material comprising or consisting of non-tobacco plant material comprises a cut width of less than or equal to 0.5 millimetres. More preferably, the shredded plant material comprising or consisting of non-tobacco plant material has a cut width of less than or equal to 0.45 millimetres. More preferably, the shredded plant material comprising or consisting of non-tobacco plant material has a cut width of less than or equal to 0.39 millimetres.

Preferably, the shredded plant material comprising or consisting of non-tobacco plant material has a cut width of at least 0.1 millimetres. More preferably, the shredded plant material comprising or consisting of non-tobacco plant material has a cut width of at least 0.2 millimetres. More preferably, the shredded plant material comprising or consisting of non-tobacco plant material has a cut width of at least 0.3 millimetres.

For example, as recited above, the shredded plant material comprising or consisting of non-tobacco plant material may have a cut width of between 0.1 millimetres and 0.5 millimetres, or between 0.15 millimetres and 0.45 millimetres, or between 0.2 millimetres and 0.39 millimetres. Provided is a method of manufacturing an aerosol-generating substrate. The aerosolgenerating substrate may be the aerosol-generating substrate according to the first aspect of the invention. The method may comprise providing a plant material. The method may comprise conditioning the plant material, wherein the conditioning includes applying an aerosol-former to the plant material. The method may comprise applying a harshness-reduction agent to the plant material, wherein the harshness-reduction agent consists of a carboxylic acid, and the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius. The method may comprise cutting the plant material to provide a shredded plant material. The method may comprise performing a drying step to provide a cut filler having a defined moisture level.

According to a second aspect of the invention, a method of manufacturing the aerosolgenerating substrate according to the first aspect of the invention is provided, wherein the method comprises:

- providing a plant material;

- conditioning the plant material, wherein the conditioning includes applying an aerosol-former to the plant material;

-applying a harshness-reduction agent to the plant material, wherein the harshness-reduction agent consists of a carboxylic acid, and the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius;

-cutting the plant material to provide a shredded plant material, and

- performing a drying step to provide a cut filler having a defined moisture level.

Preferably, the method is not limited to the above order of steps.

The plant material may be a tobacco plant material or a non-tobacco plant material, as described above.

Preferably, the conditioning step comprises applying a mixture of the aerosol former and steam to the plant material.

The conditioning step may be carried out in the Direct Conditioning Casing Cylinder (DCCC), under the same conditions as would be used in a conventional cut filler production process.

In some examples, additional additives, such as casings may additionally be applied to the plant material in the conditioning step.

In some examples, the harshness-reduction agent is applied to the plant material during the conditioning step as a mixture with the aerosol-former.

In some examples, the harshness-reduction agent is applied to the shredded plant material sequentially with the aerosol-former during the conditioning step. For example, the harshnessreduction agent may be applied to the plant material after the aerosol former is applied to the plant material during the conditioning step. In other examples, the harshness-reduction agent may be applied to the plant material before the aerosol former is applied to the plant material during the conditioning step. In other examples, the harshness-reduction agent may be applied to the plant material after the conditioning step.

Preferably, the harshness-reduction agent is applied to the plant material after the drying step, e.g. in an after-cut cylinder. Advantageously, applying the harshness-reduction agent to the plant material after the drying step e.g. in an after-cut cylinder may mitigate loss (e.g. by evaporation) of the harshness-reduction agent during the manufacturing process. Applying the harshnessreduction agent to the plant material after the drying step in an after-cut cylinder may mitigate degradation reactions with additives, for example, flavourants.

In some examples, an additional drying step may be performed after the harshness-reduction agent is applied to the plant material.

In some examples, the harshness-reduction agent may be applied to the plant material as a mixture with a flavourant. For example, the harshness-reduction agent may be applied to the plant material as a mixture with a flavourant in the after-cut cylinder, or alternatively in a secondary cylinder.

In some examples, the harshness-reduction agent may be applied sequentially to the plant material with a flavourant. The harshness-reduction agent may be applied to the plant material sequentially with a flavourant in the after-cut cylinder, or alternatively in a secondary cylinder. For example, the harshness-reduction agent may be applied to the plant material before a flavourant is applied to the plant material. In other examples, the harshness-reduction agent may be applied to the plant material after a flavourant is applied to the plant material. In some examples, the harshness-reduction agent may be applied to the plant material at the same time as a flavourant is applied to the plant material in the after-cut cylinder.

Preferably, a spraying method is used to apply the harshness-reduction agent to the plant material. Conventional machinery may be used for applying the harshness-reduction agent to the plant material.

The cutting step is preferably carried out after the conditioning step.

In other examples, the cutting step may be carried out before the conditioning step.

The cutting step may be carried out using conventional means, as would be used in a conventional cut filler production process.

The conditioned plant material is dried to a defined moisture level in a drying step. This may be carried out by conventional means, for example, in a flash tower dryer. The drying temperature will depend upon the nature of the plant material and the desired moisture level. It may be between 100 degrees Celsius and 350 degrees Celsius, for example between 150 degrees Celsius and 250 degrees Celsius.

There is provided an aerosol-generating article for use in an aerosol-generating system. The aerosol-generating article may comprise the aerosol-generating substrate according to the first aspect of the invention According to a third aspect of the invention, provided is an aerosol-generating article for use in an aerosol-generating system, the aerosol-generating article comprising the aerosol-generating substrate according to the first aspect of the invention.

The aerosol-generating article may comprise an upstream element located at a distal end of the aerosol-generating article.

The aerosol-generating article may comprise a support element located between the aerosolgenerating substrate and a proximal end of the aerosol-generating article.

Typically, the aerosol-generating article comprises an aerosol-cooling element located between the aerosol-generating substrate and a proximal end of the aerosol-generating article.

Typically, the aerosol-generating article comprises a mouthpiece element located at a proximal end of the aerosol-generating article.

Typically, the mouthpiece element located at a proximal end of the article comprises a filter element. The filter element is typically located at the proximal end of the aerosol-generating article.

Preferably, the filter element comprises a filter rod. Typically, the filter rod of the filter element consists of a gathered crimped sheet of cellulosic filtration material or a gathered embossed sheet of cellulosic filtration material.

The filter element consisting of the gathered sheet of cellulosic filtration material has a low environmental impact. The filter element consisting of the gathered sheet of cellulosic filtration material has enhanced biodegradability. The filter element consisting of the gathered sheet of cellulosic filtration material has improved sustainability.

It has been found that the aerosol-generating article comprising the filter rod consisting of the gathered crimped sheet of cellulosic filtration material or the gathered embossed sheet of cellulosic filtration material and the aerosol-generating substrate according to the first aspect comprising a harshness-reduction agent, has beneficial properties. For example, the aerosolgenerating article comprising the filter element and the aerosol-generating substrate according to the first aspect comprising a harshness-reduction agent, can enable the generation of an inhalable aerosol having an improved taste profile, has a reduced perceived sensorial harshness, and has a reduced environmental impact.

The sheet of cellulosic filtration material may have a longitudinal axis. The filter rod may have a longitudinal axis. The longitudinal axis of the sheet of cellulosic filtration material may be arranged parallel to the longitudinal axis of the filter rod. Preferably, the longitudinal axis of the sheet of cellulosic filtration material is parallel to the longitudinal axis of the filter rod.

As used herein, the term “longitudinal axis” of an object refers to the axis parallel to the longest dimension of the object. The longitudinal axis of the sheet of cellulosic filtration material may be parallel to a transport direction along which the sheet of cellulosic filtration material is fed to a gathering device. The cellulosic filtration material may be a paper material. The cellulosic filtration material may be a paper material produced with conventional wet-laid technology.

The cellulosic filtration material may comprise one or both of cellulose fibers and regenerated cellulose fibers. The cellulosic filtration material may comprise cellulose fibers. The cellulosic filtration material may comprise regenerated cellulose fibers. The cellulosic filtration material may be a non-woven material. The cellulosic filtration material may be a non-woven material of one or both cellulose fibers and regenerated cellulose fibers. The cellulosic filtration material may comprise bleached cellulose wood fibers. The cellulosic filtration material may be made from bleached cellulose wood fibers.

The cellulosic filtration material may comprise at least 50 percent by weight of cellulose fibers.

The cellulosic filtration material may comprise at least 70 percent by weight of cellulose fibers,

The cellulosic filtration material may comprise at least 85 percent by weight of cellulose fibers,

The cellulosic filtration material may comprise at least 90 percent by weight of cellulose fibers,

The cellulosic filtration material may comprise at least 95 percent by weight of cellulose fibers.

The cellulosic filtration material may comprise at least 99 percent by weight of cellulose fibers.

The cellulosic filtration material may comprise fibers selected from the group consisting of cellulose fibers, viscose fibers, rayon fibers, modal fibers, tencel fibers, lyocell fibers, glassine, parchment paper and any combinations thereof.

The filter element comprising a filter rod of cellulosic filtration material comprising the fibers reduces the environmental impact of an aerosol generating article comprising the filter element. The filter element comprising a filter rod of cellulosic filtration material comprising the fibers may be used to replace standard cellulose acetate filter elements. The filter element has an improved distribution of the fibers and thus and improved appearance. The filter element comprising the filter rod comprising the fibers has improved biodegradability. The filter element comprising cellulose fibers has one or more of improved sustainability, enhanced biodegradability and reduced environmental impact. The filter element comprising a relatively high amount of a cellulose fibers has one or more of improved sustainability, enhanced biodegradability and reduced environmental impact.

The cellulosic filtration material may be free of cellulose acetate. The provision of a filter element comprising a filter rod formed from the gathered cellulosic filtration material free of cellulose acetate improves one or more of the environmental impact and the biodegradability of the filter element.

The perimeter of the filter rod may be of between 22.5 millimeters and 24.3 millimeters. The perimeter of the filter rod may be of between 22.8 millimeters and 24.0 millimeters. The filter element may have a resistance-to-draw (RTD) of between 1.20 millimeter of water (mmWg) per millimeter length of the filter rod and 3.43 millimeter of water per millimeter length of the filter rod. The filter element may have a resistance-to-draw (RTD) of between 1 .94 millimeter of water per millimeter length of the filter rod and 2.50 millimeter of water per millimeter length of the filter rod. A filter rod having a perimeter and an RTD within such ranges may be compatible with its usage in standard aerosol-generating articles.

The filter element may comprise an additive for reducing one or more of phenols and cresols. Preferably, the additive comprises polyethylene glycol (PEG), triacetin (TA) or triethyl citrate (TEC).

At least a portion of the filter rod may be circumscribed by a sheet of wrapper material. The wrapper material may be a paper wrapper material, such as a plug wrap and/or tipping paper. The filter rod may be fully circumscribed by the sheet of wrapping material. The sheet of wrapper material may be folded around the filter rod. The sheet of wrapper material may be arranged radially around the filter rod. The sheet of wrapper material may radially abut the filter rod.

The sheet of wrapper material improves the structural stability of the filter rod. Usage of the sheet of paper wrapper material provides improved biodegradability of the filter element. Usage of the sheet of paper wrapper material reduces the environmental impact of the filter element.

The filter element may have a length of between 5 millimeters and 130 millimeters. The filter element may have a length of between 7 millimeters and 50 millimeters. The filter element may have a length of between 10 millimeters and 35 millimeters.

A filter element having a length within such ranges is compatible with its usage in standard aerosol-generating articles. A filter element having a length within such ranges may provide sufficient removal of undesired compounds from the aerosol.

The aerosol-generating article may further comprise a wrapper, preferably a paper wrapper. The paper wrapper may be arranged circumscribing at least a portion of one or more of the aerosol-forming substrate and the filter element. The wrapper improves the structural stability of the aerosol-generating article.

The aerosol-generating article may comprise a plug wrap and/or tipping paper. The tipping paper may be used to display information to the user. The tipping paper may improve structural stability of the aerosol-generating article.

In some examples, the aerosol-generating article is a combustible aerosol-generating article. For example, the aerosol-generating article may be a conventional cigarette. A conventional cigarette typically has a substrate section and a filter section.

In other examples, the aerosol-generating article is a heat-not-burn aerosol-generating article.

Typically, the aerosol-generating article comprises a susceptor.

In some examples, the susceptor is in direct contact with the aerosol-generating substrate.

The susceptor may be arranged within at least a portion of the aerosol-forming substrate. The susceptor may be embedded within the aerosol-forming substrate. The susceptor may be configured to heat the aerosol-forming substrate. The susceptor may be configured to volatize the aerosol-forming substrate. The susceptor may be configured to be heated by an induction coil of an aerosol-generating device. There is provided an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating article according to the third aspect. The aerosol-generating system may comprise an aerosol-generating device configured to heat the aerosol-generating substrate of the aerosol-generating article.

According to a fourth aspect of the invention, provided is an aerosol-generating system comprising: an aerosol-generating article according to the third aspect; and an aerosol-generating device configured to heat the aerosol-generating substrate of the aerosol-generating article.

The aerosol-generating device may comprise a cavity. The cavity may be configured to receive the aerosol-forming substrate. The cavity may be configured to receive at least a portion of the aerosol-generating article. The cavity may be configured as a heating chamber.

The aerosol-generating device may comprise a heating assembly. The heating assembly may be configured to heat the aerosol-forming substrate. The heating assembly may be configured to volatilize at least a portion of the aerosol-forming substrate. The heating assembly may comprise a heating element. The heating element may be configured to heat the aerosol-forming substrate. The heating assembly may be an inductive heating assembly or a resistive heating assembly. The resistive heating assembly may comprise a resistive heating element. The inductive heating assembly may comprise an inductive heating element comprising susceptor material. The inductive heating assembly may comprise an induction coil. The induction coil may be configured to inductively heat the susceptor material. The induction coil may be configured to inductively heat the susceptor member of the aerosol-forming substrate when the aerosol-generating article is received in the cavity of the aerosol-generating device.

Provided is a use of a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius as a harshness-reduction agent

According to a fifth aspect, there is provided a use of a carboxylic acid having a vapor pressure of from 0.001 to 1 .00 Torr at 25 degrees Celsius as a harshness-reduction agent.

Preferably, this aspect relates to the use of a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius for at least partially reducing harshness in an aerosol, more preferably an inhalable aerosol.

Preferably, the fifth aspect relates to the use of the carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius in an aerosol-generating substrate of the first aspect to at least partially reduce harshness in an inhalable aerosol from a heated aerosolgenerating article according to the third aspect or the heated aerosol-generating system of the fourth aspect.

Preferably, the use is of improving a taste profile of the inhalable aerosol.

Preferably, the use is of enhancing the taste experience of the inhalable aerosol. It goes without saying that the features described in connection with the carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius described hereinbefore apply to the fifth aspect.

Provided is a method of using a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius as a harshness-reduction agent to at least partially reduce harshness from an inhalable aerosol.

According to a sixth aspect, there is provided a method of using a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius as a harshness-reduction agent to at least partially reduce harshness from an inhalable aerosol.

Preferably, the method is of partially reducing perceived harshness from an inhalable aerosol generated by the aerosol-generating article of the third aspect, or the aerosol-generating system of the fourth aspect.

It goes without saying that the features described in connection with the carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius described hereinbefore apply to the sixth aspect.

As referred to, the term “aerosol-generating article” refers to an aerosol-generating article for producing an aerosol. The aerosol-generating article may refer to a heat-not-burn article where the aerosol-generating substrate is intended to be heated rather than combusted in order to release volatile compounds that can form an aerosol, or the aerosol-generating article may refer to a conventional cigarette..

As referred to, the term “aerosol-generating substrate” is used to describe a substrate comprising aerosol-generating material that is capable of releasing upon heating volatile compounds that can generate an aerosol.

As referred to, the term “aerosol” is used to describe a dispersion of solid particles, or liquid droplets, or a combination of solid particles and liquid droplets, in a gas. The aerosol may be visible or invisible. The aerosol may include vapours of substances that are ordinarily liquid or solid at room temperature as well as solid particles, or liquid droplets, or a combination of solid particles and liquid droplets.

As referred to, the term “aerosol former” refers to a component that can be volatilized and convey a desired substance, for example, nicotine and/or flavouring, in an aerosol when the aerosol-generating material is heated above the specific volatilization temperature of the aerosol former. An aerosol former may be any suitable compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the heated aerosol-generating article. Different aerosol formers vaporize at different temperatures. Thus, an aerosol former may be chosen based on its ability to remain stable at or around room temperature but volatize at a higher temperature, for example from 40 to 450 degrees Celsius. As used, the term “pK_a” is the negative base-10 logarithm of the acid dissociation constant ( _a) of a solution and is used to describe the strength of an acid.

As referenced, the term “boiling point” refers to the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor, measured at 1 atmosphere.

As referred to, the “vapor pressure” of a liquid is the equilibrium pressure of a vapor above its liquid; that is, the pressure of the vapor resulting from evaporation of a liquid above a sample of the liquid in a closed container.

As referred to, the term “carboxylic acid” is used to describe an organic compound comprising a carboxyl group. That is, a carboxylic acid is a compound comprising a -COOH group attached to one of the atoms in the compound.

As referenced, the term “aliphatic carboxylic acid” is used to describe a carboxylic acid compound which does not contain an aromatic structure. The aliphatic carboxylic acid may be saturated or unsaturated. The aliphatic carboxylic acid may be linear or branched.

As referenced, the term “aromatic carboxylic acid” is used to describe a compound which contains an aromatic structure and a -COOH group. The -COOH group may be attached directly to the aromatic structure, or the -COOH group may be attached to another atom present in the compound.

As referred to, the term “monocarboxylic acid” is used to describe a carboxylic acid which comprises one carboxyl group attached to a carbon atom in the carboxylic acid compound. That is, a carboxylic acid comprising one -COOH group attached to a carbon atom.

As referenced, the term “geminal dicarboxylic acid” is used to describe a carboxylic acid comprising two carboxyl groups attached to the same carbon atom. That is, a carboxylic acid comprising two -COOH groups attached to the same carbon atom. A geminal dicarboxylic acid may also be referred to as a gem-dicarboxylic acid.

As referred to, the term “non-geminal dicarboxylic acid” is used to describe a carboxylic acid comprising two carboxyl groups attached to two different carbon atoms. That is, a carboxylic acid comprising two -COOH groups attached to two different carbon atoms.

As used, “plant material” is used to refer to any substance or matter which is derived from, or a part of, a plant, including, but not limited to, leaves, stems, seeds, flower, fruits, roots or bark.

With reference to the present invention, the term “tobacco” describes any plant member of the genus Nicotiana.

The term “tobacco material” is used to refer to any plant material comprising tobacco, including, but not limited to, tobacco leaf lamina, tobacco rib, tobacco stem and tobacco stalk.

The term “non-tobacco plant material”, is used to refer a plant material which does not comprise tobacco. Thus, the non-tobacco plant material is substantially free of tobacco (for example, the non-tobacco-containing material contains of from less than 1 weight percent of tobacco, preferably of from less than 0.5 weight percent of tobacco, and even more preferably of from less than 0.1 weight percent of tobacco) or does not contain any determinable amount of tobacco. Examples of a non-tobacco plant material include botanical plant materials such as, but not limited to, clove, star anise, rosemary, peppermint, sage, chamomile, and lavender.

As used, the term “cut filler” describes a blend of shredded plant material, such as tobacco plant material, including, in particular, one or more of leaf lamina, processed stems and ribs, homogenised plant material. During the process of producing cut filler, the shredded plant material is conditioned, typically through the application of aerosol former and steam and then the conditioned plant material is dried to a defined moisture level. The cut filler may also comprise other after-cut, filler tobacco or casing, which are typically combined with the dried, conditioned plant material in an after-cut cylinder. For the purposes of the present invention, the term “cut filler” refers to the shredded plant material after it has been subjected to the conditioning and drying steps, and after it has been combined with after-cut and any other additives in the aftercut cylinder.

As referred to, the term “nicotine” is used to describe nicotine, a nicotine base or a nicotine salt.

As referenced, the term “flavourant” is used to refer to a chemical compound which provides a desirable flavour or scent. Examples of flavourants include, but are not limited to vanillin, linalool, menthol, guaiacol, thymol, coumarin, eugenol, cinnamaldehyde and geraniol.

As referenced, the term “aerosol-generating device” is used to describe a device that interacts with an aerosol generating substrate of an aerosol generating article to generate an aerosol. In particular, the term “aerosol-generating device” is used to describe a device that heats an aerosol generating substrate of an aerosol generating article to generate an aerosol.

As used herein, “dry weight” refers to the weight of a particular non-water component relative to the sum of the weights of all non-water components in a mixture, expressed as a percentage. The composition of aqueous mixtures may be referred to by “percentage dry weight.” This refers to the weight of the non-water components relative to the weight of the entire aqueous mixture, expressed as a percentage.

As used, the term “sheet” refers to a planar element having both a length and a width that are substantially greater than a thickness of the sheet. The sheet substantially extends within a plane. The length and the width of the sheet may be at least 500-times greater than the thickness of the sheet. The length and the width of the sheet may be at least 1000-times greater than the thickness of the sheet. The sheet may have a rectangular shape. The sheet may have an elongated rectangular shape. The sheet may be a strip.

The sheet may be a continuous sheet. As used herein, the term “continuous sheet” refers to a sheet having a length that is substantially greater than a width. The continuous sheet may be provided on a bobbin.

As used, the term “length of the sheet” refers to the spatial extent of the sheet along a longitudinal axis of the sheet. Preferably, the length of the sheet is constant. The term “width of the sheet” refers to the spatial extent of the sheet along an axis perpendicular to a longitudinal axis of the sheet. As used herein, the term “pre-determined with” refers to the width of the sheet before it is further processed, for example before the sheet is crimped or embossed and/or before the sheet is gathered. Preferably, the width of the sheet is constant along a longitudinal axis of the sheet. The length and the width of the sheet extend with in a plane. The term “thickness of the sheet” refers to the spatial extent of the sheet along an axis perpendicular to the plane in which the length of the sheet and the width of the sheet extend. Preferably, the thickness of the sheet is constant.

As used, the term “gathering” or “gathered” refers to forming the sheet of cellulosic filtration material or crimped sheet of cellulosic filtration material or embossed sheet of cellulosic filtration material into a pre-determined shape, for example a rod. The sheet may be convoluted, or otherwise compressed or constricted substantially transversely to a central longitudinal axis of the sheet into rod form. The sheet of cellulosic filtration material may be gathered in a gathering device. The sheet of cellulosic filtration material may be gathered into the filter rod by passing the sheet of cellulosic filtration material through a converging funnel. The converging funnel may progressively gather the sheet of cellulosic filtration material into a rod shape. The sheet of cellulosic filtration material may be gathered into the filter rod by passing the crimped or embossed sheet of cellulosic filtration material through a converging funnel. The converging funnel may progressively gather the crimped or embossed sheet of cellulosic filtration material into a rod shape.

As used, the term “crimped” or “crimping” refers to a process of forming a plurality of corrugations on the sheet of cellulosic filtration material. Crimping may be carried out using a pair of crimping rollers. Corrugations on a sheet may be formed by crimping rollers. Crimping rollers may include corrugations on their surface. The sheet of cellulosic filtration material may be crimped before the sheet is gathered. In other words, the crimped sheet of cellulosic filtration material may be gathered.

As used, the term “corrugations” denotes a plurality of ridges formed from alternating peaks and troughs joined by corrugation flanks. This includes, but is not limited to, corrugations having a square wave profile, sinusoidal wave profile, triangular profile, sawtooth profile, or any combination thereof. Corrugations can be defined on rollers, such as crimping rollers, or on the sheet. Corrugations on a roller denote a plurality of ridges formed on an outer surface of the roller. Corrugations on the sheet refer to a plurality of ridges when the sheet is laid on a planar surface without stretching the sheet itself.

As used, a “crimping roller” is a roller used for crimping the sheet. The crimping roller defines an outer surface and a rotational axis. The outer surface comprises a plurality of corrugations.

Crimping improves control over the way the sheet of cellulosic filtration material is gathered. Crimping provides improved control of the porosity of the filter rod. Crimping improves the control of the airflow properties of the filter rod. Crimping improves the visual appearance of the filter rod. Crimping improves the control of the resistance-to-draw (RTD) of the filter rod.

As used, the term "embossed" or “embossment” or “embossing” refers to protrusions formed in the surface of the sheet of cellulosic filtration material. The sheets may embossed by a pair of opposed rotating profiled embossing rollers. The sheet may be passed through a nip between the rollers and conforms to their profiles. The embossing rollers may apply an embossing pattern to sheet. The embossing rollers may have a profile comprising a plurality of small square based pyramids.

Embossing improves control over the way the sheet of cellulosic filtration material is gathered. Embossing provides improved control of the porosity of the filter rod. Embossing improves the control of the airflow properties of the filter rod. Embossing improves the visual appearance of the filter rod. Embossing improves the control of the resistance-to-draw (RTD) of the filter rod.

As used, the term “perimeter” of an object refers to the total length of a line around a crosssection of an external surface of the object. In other words, the perimeter refers to the outer perimeter of the object. The perimeter may be a circumference.

As used, the “length of the filter rod” refers to the spatial extent of the filter rod along a longitudinal axis of the filter rod.

The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example Ex1. An aerosol-generating substrate for use in an aerosol-generating system, the aerosol-generating substrate comprising: a cut filler comprising shredded plant material, an aerosol former, and a harshness-reduction agent, wherein the harshness-reduction agent consists of a carboxylic acid, wherein the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius.

Example Ex2. The aerosol-generating substrate according to Example Ex1 , wherein the carboxylic acid has a vapor pressure of from 0.005 to 0.95 Torr at 25 degrees Celsius.

Example Ex3. The aerosol-generating substrate according to any of Example Ex1 to Example Ex2, wherein the carboxylic acid has a vapor pressure of from 0.01 to 0.90 Torr at 25 degrees Celsius.

Example Ex4. The aerosol-generating substrate according to any of Example Ex1 to Example Ex3 wherein the carboxylic acid has a vapor pressure of from 0.012 to 0.85 Torr at 25 degrees Celsius. Example Ex5. The aerosol-generating substrate according to any of Example Ex1 to Example Ex4, wherein the pKa of the carboxylic acid is of from 3.20 to 5.50 in water at 25 degrees Celsius.

Example Ex6. The aerosol-generating substrate according to any of Example Ex1 to Example Ex5, wherein the pKa of the carboxylic acid is of from 3.25 to 5.30 in water at 25 degrees Celsius.

Example Ex7. The aerosol-generating substrate according to any of Example Ex1 to Example Ex6, wherein the pKa of the carboxylic acid is of from 3.30 to 5.20 in water at 25 degrees Celsius.

Example Ex8. The aerosol-generating substrate according to any of Example Ex1 to Example Ex7, wherein the pKa of the carboxylic acid is of from 3.35 to 5.15 in water at 25 degrees Celsius.

Example Ex9. The aerosol-generating substrate according to any of Example Ex1 to Example Ex8, wherein the pKa of the carboxylic acid is of from 3.4 to 4.50.

Example Ex10. The aerosol-generating substrate according to any of Example Ex1 to Example Ex9, wherein the boiling point of the carboxylic acid is of from 150 to 310 degrees Celsius.

Example Ex11. The aerosol-generating substrate according to any of Example Ex1 to Example Ex10, wherein the boiling point of the carboxylic acid is of from 160 to 270 degrees Celsius.

Example Ex12. The aerosol-generating substrate according to any of Example Ex1 to Example Ex11, wherein the boiling point of the carboxylic acid is of from 170 to 260 degrees Celsius.

Example Ex13. The aerosol-generating substrate according to any of Example Ex1 to Example Ex12, wherein the boiling point of the aerosol-generating carboxylic acid is of from 180 to 255 degrees Celsius.

Example Ex14. The aerosol-generating substrate according to any of Example Ex1 to Example Ex13, wherein the carboxylic acid does not decompose at or before its boiling point.

Example Ex15. The aerosol-generating substrate according to any of Example Ex1 to Example Ex14, wherein the aerosol-generating substrate is stable to decarboxylation at temperatures of greater than 300 degrees Celsius and less than 450 degrees Celsius.

Example Ex16. The aerosol-generating substrate according to any of Example Ex1 to Example Ex15, wherein the carboxylic acid is a monocarboxylic acid.

Example Ex17. The aerosol-generating substrate according to any of Example Ex1 to Example Ex16, wherein the carboxylic acid is an aliphatic carboxylic acid. Example Ex18. The aerosol-generating substrate according to any of Example Ex1 to Example Ex17, wherein the carboxylic acid has a chain length of from 3 to 8 carbon atoms.

Example Ex19. The aerosol-generating substrate according to any of Example Ex1 to Example Ex18, wherein the carboxylic acid is selected from lactic acid, levulinic acid, succinic acid, crotonic acid, sorbic acid, trans-2-hexenoic acid, 3-hexenoic acid, 2- ethylbutyric acid, hexanoic acid, benzoic acid, 5-methyl-2-fuoric acid and cyclohexane carboxylic acid.

Example Ex20. The aerosol-generating substrate according to any of Example Ex1 to 19, wherein the carboxylic acid is lactic acid, levulinic acid or crotonic acid.

Example Ex21. The aerosol-generating substrate according to any of Example Ex1 to 20, wherein the carboxylic acid is an alpha-hydroxy carboxylic acid.

Example Ex22. The aerosol-generating substrate according to any of Example Ex1 to 21, wherein the carboxylic acid lactic acid.

Example Ex23. The aerosol-generating substrate according to any of Example Ex1 to Example Ex22, wherein the carboxylic acid is configured to directly protonate nicotine in an aerosol generated by heating the aerosol-generating substrate.

Example Ex24. The aerosol-generating substrate according to any of Example Ex1 to Example Ex23, wherein the carboxylic acid is present at 0.1 to 10 weight percent on a dry weight basis, preferably of from 0.5 to 7.5 weight percent on a dry weight basis, preferably of from 0.75 to 5 weight percent on a dry weight basis, preferably of from 1.0 to 3 weight percent on a dry weight basis.

Example Ex25. The aerosol-generating substrate according to any of Example Ex1 to Example Ex24, wherein the substrate comprises a single harshness-reduction agent.

Example Ex26. The aerosol-generating substrate according to any of Example Ex1 to Example Ex25, wherein the aerosol-generating substrate does not comprise a geminal dicarboxylic acid.

Example Ex27. The aerosol-generating substrate according to any of Example Ex1 to Example Ex26, wherein the substrate is a solid aerosol-generating substrate.

Example Ex28. The aerosol-generating substrate according to any of Example Ex1 to Example Ex27, wherein the shredded plant-material comprises tobacco material.

Example Ex29. The aerosol-generating substrate according to any of Example Ex1 to Example Ex28, wherein the shredded plant-material consists of tobacco material.

Example Ex30. The aerosol-generating substrate according to any of Example Ex1 to Example Ex29, wherein the tobacco material comprises or consists of one or more of tobacco lamina, tobacco rib, tobacco stem and tobacco stalk. Example Ex31 . The aerosol-generating substrate according to any of Example Ex1 to Example Ex30, wherein the tobacco material comprises at least 25 percent by weight of shredded tobacco lamina.

Example Ex32. The aerosol-generating substrate according to any of Example Ex1 to Example Ex31 , wherein the shredded plant material comprises a non-tobacco plant material.

Example Ex33. The aerosol-generating substrate according to any of Example Ex1 to Example Ex27, wherein the shredded plant material consists of a non-tobacco plant material.

Example Ex34. The aerosol-generating substrate according to any of Example Ex32 to 33, wherein the shredded non-tobacco plant material comprises or consists of one or more of non-tobacco plant leaf lamina, stems, seeds, root, bark, flower and fragments of ribs.

Example Ex35. The aerosol-generating substrate according to any of Example Ex32 to 34, wherein the non-tobacco plant material comprises or consists of one or more of tea, coffee, star anise, lavender, clove, peppermint, chamomile, rosemary, eucalyptus, ginger, dill seed, thyme, oregano and cumin.

Example Ex36. The aerosol-generating substrate according to any of Example Ex1 to Example Ex35, wherein the substrate comprises nicotine.

Example Ex37. The aerosol-generating substrate according to any one of Example Ex1 to Example Ex36, wherein the total nicotine content is of from 0.5 to 5 percent by weight on a dry weight basis, preferably of from 1 percent by weight to 4 percent by weight, on a dry weight basis, and more preferably of from 1.5 percent by weight to 3 percent by weight, on a dry weight basis.

Example Ex38. The aerosol-generating substrate according to any of Example Ex1 to Example Ex37, wherein the substrate comprises of from 50 to 95 weight percent of the cut filler on a dry weight basis, preferably of from 60 to 90 weight percent of the cut filler on a dry weight basis, preferably of from 70 to 85 weight percent of the cut filler on a dry weight basis.

Example Ex39. The aerosol-generating substrate according to any of Example Ex1 to Example Ex38, wherein the aerosol former comprises or consists of propylene glycol, triethylene glycol, 1 ,3-butanediol, glycerine, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate, and dimethyl tetradecanedioate.

Example Ex40. The aerosol-generating substrate according to any one of Example Ex1 to Example Ex39, wherein the aerosol-generating substrate comprises the aerosol former in at least 10 percent by weight, on a dry weight basis, preferably at least 12 percent by weight of aerosol former, more preferably at least 15 percent by weight of aerosol former, on a dry weight basis. Example Ex41 . The aerosol-generating substrate according to any one of Example Ex1 to Example Ex40, wherein the aerosol-generating substrate comprises less than or equal to 40 percent by weight of the aerosol former, preferably less than or equal to 30 percent by weight of aerosol former, more preferably less than or equal to 25 percent by weight of aerosol former, more preferably less than or equal to 20 percent by weight, on a dry weight basis.

Example Ex42. The aerosol-generating substrate according to any of Example Ex1 to 41 , wherein the shredded-plant material is impregnated with aerosol-former.

Example Ex43. The aerosol-generating substrate according to any of Example Ex1 to Example Ex42, wherein the aerosol-former is provided as a coating on a surface of the shredded-plant material.

Example Ex44. The aerosol-generating substrate according to any of Example Ex1 to Example Ex43, wherein the substrate comprises a flavourant.

Example Ex45. The aerosol-generating substrate according to Example Ex44, wherein the flavourant comprises or consists of one or more of menthol, peppermint oil, gamma octalactone, vanillin, ethyl vanillin, methyl salicylate, linalool, bergamot oil, geranium oil, ginger oil, and lemon oil.

Example Ex46. The aerosol-generating substrate according to any of Example Ex1 to Example Ex45, wherein the shredded plant material comprising or consisting of tobacco material has an average cut width of between 0.75 millimetres and 2 millimetres, preferably between 0.8 millimetres and 1.75 millimetres, preferably between 0.85 millimetres and 1.5 millimetres, preferably between 0.9 millimetres and 1.25 millimetres, particularly preferably of approximately 1 millimetre.

Example Ex47. The aerosol-generating substrate according to any of Example Ex1 to 46, wherein the shredded plant material comprising or consisting of non-tobacco plant material may have a cut width of between 0.1 millimetres and 0.5 millimetres, or between 0.15 millimetres and 0.45 millimetres, or between 0.2 millimetres and 0.39 millimetres.

Example Ex48. A method of manufacturing the aerosol-generating substrate according to any of Example Ex1 to Example Ex47, wherein the method comprises:

- providing a plant material;

- conditioning the plant material, wherein the conditioning includes applying an aerosolformer to the plant material

- applying a harshness-reduction agent to the plant material, wherein the harshnessreduction agent consists of a carboxylic acid and the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius;

- cutting the plant material to provide a shredded plant material, and

- performing a drying step to provide a cut-filler having a defined moisture level. Example Ex49. The method of manufacturing the aerosol-generating substrate according to Example Ex48, wherein the conditioning step comprises applying a mixture of the aerosol former and steam to the plant material.

Example Ex50. The method of manufacturing the aerosol-generating substrate according to any of Example Ex48 to Example Ex49, wherein the harshness-reduction agent is applied to the plant material during the conditioning step as a mixture with the aerosolformer.

Example Ex51 . The method of manufacturing the aerosol-generating substrate according to any one of Example Ex48 to Example Ex49, wherein the harshness-reduction agent is applied to the shredded plant material sequentially with the aerosol-former during the conditioning step.

Example Ex52. The method of manufacturing the aerosol-generating substrate according to any of Example Ex48 to Example Ex49, wherein the harshness-reduction agent is applied to the plant material after the conditioning step.

Example Ex53. The method of manufacturing the aerosol-generating substrate according to any of Example Ex 48 to Example Ex 49 and according to Example Ex 52, wherein the harshness-reduction agent is applied to the plant material after the drying step.

Example Ex54. The method of manufacturing the aerosol-generating substrate according to Example Ex48 and Ex53, wherein an additional drying step is performed after the harshness-reduction agent is applied to the plant material.

Example Ex55. The method of manufacturing the aerosol-generating substrate according to any of Example Ex52 to Example Ex54, wherein the harshness-reduction agent is applied to the plant material as a mixture with a flavourant.

Example Ex56. The method of manufacturing the aerosol-generating substrate according to any of Example Ex52 to Example Ex54, wherein the harshness-reduction agent is applied to the plant material before or after a flavourant has been applied to the plant material.

Example Ex57. An aerosol-generating article for use in an aerosol-generating system, the aerosol-generating article comprising the aerosol-generating substrate according to any of Example Ex1 to Example Ex47.

Example Ex58. The aerosol-generating article according to Example Ex57 wherein the aerosol-generating article comprises an upstream element located at a distal end of the aerosol-generating article.

Example Ex59. The aerosol-generating article according to any of Example Ex57 to Example Ex58, wherein the aerosol-generating article comprises a support element located between the aerosol-generating substrate and a proximal end of the aerosolgenerating article. Example Ex60. The aerosol-generating article according to any of Example Ex57 to Example Ex59, wherein the aerosol-generating article comprises an aerosol-cooling element located between the aerosol-generating substrate and a proximal end of the aerosol-generating article.

Example Ex61 . The aerosol-generating article according to any of Example Ex57 to Example Ex60, wherein the aerosol-generating article comprises a mouthpiece element located at a proximal end of the aerosol-generating article.

Example Ex62. The aerosol-generating article according to Example Ex61 , wherein the mouthpiece element comprises a filter element.

Example Ex63. The aerosol-generating article according to Example Ex62, wherein the filter element comprises a filter rod, preferably wherein the filter rod of the filter element consists of a gathered crimped sheet of cellulosic filtration material or a gathered embossed sheet of cellulosic filtration material.

Example Ex64. The aerosol-generating article according to any of Examples Ex63, wherein the cellulosic filtration material is a paper material.

Example Ex65. The aerosol-generating article according to any of Examples Ex63 to Example Ex 64, wherein the cellulosic filtration material comprises one or both of cellulose fibers and regenerated cellulose fibers.

Example Ex66. The aerosol-generating article according to Examples Ex65, wherein the cellulosic filtration material comprises at least 70 percent by weight of cellulose fibers, optionally wherein the cellulosic filtration material comprises at least 85 percent by weight of cellulose fibers, optionally wherein the cellulosic filtration material comprises at least 90 percent by weight of cellulose fibers.

Example Ex67. The aerosol-generating article according to any of Examples Ex65 to Example Ex66, wherein the cellulosic filtration material comprises fibers selected from the group consisting of cellulose fibers, viscose fibers, rayon fibers, modal fibers, tencel fibers, lyocell fibers, glassine, parchment paper, and any combinations thereof.

Example Ex68. The aerosol-generating article according to any of Examples Ex62 to Example Ex70, wherein the filter element comprises an additive for reducing one or more of phenols or cresols, preferably wherein the additive is selected from polyethylene glycol (PEG), triacetin (TA) and triethyl citrate (TEC).

Example Ex69. The aerosol-generating article according to any of Examples Ex63 to Example Ex68, wherein the longitudinal axis of the sheet of cellulosic filtration material is parallel to a longitudinal axis of the filter rod.

Example Ex70. The aerosol-generating article according to any of Examples Ex65 to Example Ex71 , wherein at least a portion of the filter rod is circumscribed by a sheet of wrapper material, preferably a paper wrapper material, such as a plug wrap and/or tipping paper. Example Ex71. The aerosol-generating article according to any of Example Ex57 to Example Ex70, wherein the aerosol-generating article comprises a susceptor.

Example Ex72. The aerosol-generating article according to Example Ex71 , wherein the susceptor is in direct contact with the aerosol-generating substrate.

Example Ex73. An aerosol-generating system comprising: an aerosol-generating article according to any of Example Ex57 to Example Ex72; and an aerosol-generating device configured to heat the aerosol-generating substrate of the aerosolgenerating article.

Example Ex75. Use of a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius as a harshness-reduction agent.

Example Ex76. Use according to Example Ex75 for at least partially reducing harshness in an aerosol, more preferably an inhalable aerosol.

Example Ex77. Use according to any of Examples Ex75 to Ex76 in the aerosol-generating substrate of any of Examples Ex1 to Ex47 to at least partially reduce harshness in an inhalable aerosol from a heated aerosol-generating article according to any of Examples Ex57 to Ex72 or the heated aerosol-generating system of Example Ex73.

Example Ex78. Use according to any of Examples Ex75 to Ex77, to improve a taste profile of an inhalable aerosol.

Example Ex79. Use according to any of Examples Ex75 to Ex78, to enhance the taste experience of the inhalable aerosol.

Example Ex80. A method of using a carboxylic acid having a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius as a harshness-reduction agent to at least partially reduce harshness from an inhalable aerosol.

Example Ex81. The method according to Example Ex80, comprising at least partially reducing perceived harshness from an inhalable aerosol generated by the aerosol-generating article of any of Examples Ex57 to Ex72, or the aerosol-generating system of Example Ex73.

Example 1

A reference aerosol-generating substrate comprising cut filler was prepared in accordance with a conventional method known in the art. The reference aerosol-generating substrate comprised around 82 weight percent tobacco cut filler and 18 weight percent glycerin, on a dry weight basis.

Sample 1 was an aerosol-generating substrate comprising cut filler, which comprised around 81.4 weight percent tobacco cut filler, 17.9 weight percent glycerin, and 0.7 weight percent lactic acid, on a dry weight basis. The lactic acid was applied by injection to the substrate to form sample 1. Sample 1 and the reference aerosol-generating substrate sample were each heated to a temperature of between 250 degrees Celsius and 260 degrees Celsius to generate inhalable aerosols.

The harshness in mouth and throat intensity for the inhalable aerosols generated by heating sample 1 and the reference aerosol-generating substrate was assessed by eight panellists as a function of puff number over 9 puffs.

The panellists ranked the harshness in mouth and throat intensity experienced for each puff from zero to ten. A value of ten indicated a high intensity and a high perceived sensorial harshness, and a value of zero indicated no intensity and no sensorial harshness. The ranking for each puff was then averaged.

It was found that inclusion of lactic acid in sample 1 advantageously resulted in a decrease in harshness in mouth and throat intensity felt, compared to the harshness in mouth and throat intensity felt from the inhalable aerosol generated by heating the reference sample.

Accordingly, it was found that an aerosol-generating substrate according to the present invention could effectively reduce perceived sensorial harshness and mouth and throat irritation. Example 2

A reference aerosol-generating substrate which comprised cut filler was prepared in the same way as the reference sample described above in connection with Example 1 .

Sample 2 was an aerosol-generating substrate comprising cut filler, which comprised around 80.7 weight percent tobacco cut filler, 17.7 weight percent glycerine, and 1.6 weight percent lactic acid, on a dry weight basis. The lactic acid was applied by injection to the substrate to form sample 2.

Sample 2 and the reference sample were each heated to a temperature of between 250 degrees Celsius and 260 degrees Celsius to generate inhalable aerosols.

The harshness in mouth and throat intensity for the inhalable aerosols generated by heating sample 2 and the reference aerosol-generating substrate, was assessed by eight panellists as a function of puff number over 9 puffs.

It was found that inclusion of lactic acid in sample 2 advantageously resulted in a decrease in harshness in mouth and throat intensity felt, compared to the harshness in mouth and throat intensity felt from the inhalable aerosol generated by heating the reference sample.

Accordingly, it was found that an aerosol-generating substrate according to the present invention could effectively reduce perceived sensorial harshness and mouth and throat irritation.

Furthermore, it was found that the average intensity felt in each of the first three puffs for sample 2 was lower than the average intensity felt in each of the first three puffs for sample 1. Therefore, a higher amount of the harshness-reduction agent in the aerosol-generating substrate may further reduce harshness and mouth and throat irritation felt in the earlier puffs for an aerosolgenerating article.

Example 3

The effect of a harshness-reduction agent on nicotine delivery from the aerosol-generating substrate was assessed.

A reference aerosol-generating substrate comprising cut-filler was prepared in the same way as described above in connection with Examples 1 and 2.

An aerosol-generating substrate comprising cut-filler was prepared, which comprised around 80.7 weight percent tobacco cut filler, 17.7 weight percent glycerin, and 1.6 weight percent lactic acid, on a dry weight basis. The lactic acid was applied by injection to this substrate in order to form sample 3.

A further aerosol-generating substrate was prepared which comprised around 80.7 weight percent tobacco cut filler, 17.7 weight percent glycerin, and 1.6 wt% lactic acid, on a dry weight basis. The lactic acid was applied to this sample using a spray method in order to form sample 4. A spray application method would be familiar to the skilled person.

The reference sample, sample 3 and sample 4 were each heated to generate an inhalable aerosol. The aerosol was trapped and analysed using gas chromatography, and the content of nicotine contained in each of the aerosols generated by heating the reference sample, sample 3 and sample 4 was determined.

It was found that the content of nicotine in the aerosols generated by samples 3 and 4, which each contained a harshness-reduction agent, were comparable to the content of nicotine contained in the aerosol generated by heating the reference aerosol-generating substrate, which did not include a harshness-reduction agent.

Therefore, it was advantageously found that substrates according to the present invention could effectively reduce sensorial harshness and mouth and throat irritation, without compromising on the delivery of nicotine to the user.

Example 4

The content of a harshness reduction agent contained in an aerosol generated by heating an aerosol-generating substrate was assessed, and the transfer yield of the harshness-reduction agent from the substrate to the aerosol was calculated.

A reference aerosol-generating substrate was prepared for testing. The reference sample in this example was a tobacco-free cast leaf aerosol-generating substrate, which contained 3.72 weight percent of lactic acid and 1.5 weight percent of exogenous nicotine.

Sample 5 was prepared, which was an aerosol-generating substrate comprising cut filler. Sample 5 comprised around 81.4 weight percent tobacco cut filler, 17.9 weight percent glycerin, and 0.7 weight percent lactic acid, on a dry weight basis. Sample 6 was prepared, which was an aerosol-generating substrate comprising cut filler. The aerosol-generating substrate comprising cut filler comprised around 80.7 weight percent tobacco cut filler, 17.7 weight percent glycerin, and 1.6 weight percent lactic acid, on a dry weight basis.

Each of the reference sample, sample 5 and sample 6 were heated to generate an aerosol. The aerosol generated by each of the samples was trapped and analysed using ion chromatography and the content of lactic acid contained in each of the aerosols was determined. The content of lactic acid determined in each of the aerosols was compared to the initial content of lactic acid in each of the substrates, and the transfer yield was then calculated.

It was found that the transfer yield of lactic acid from sample 5 was 12.2 % and the transfer yield of lactic acid from sample 6 was 12.4 %.

In comparison, it was found that the transfer yield of lactic acid in the reference sample was 3.3 %.

Therefore, it was advantageously found that substrates according to the present invention have an improved transfer yield of harshness-reduction agent from the substrate to the aerosol, in comparison to prior art aerosol-generating substrates.

Advantageously, and without wishing to be bound by theory, the aerosol-generated by the present invention has a higher transfer yield of lactic acid than aerosols generated by prior art aerosol-generating substrates. Therefore, there is a higher proportion of lactic acid available in the aerosol for protonation of nicotine, which may lead to a reduction in sensorial harshness and mouth and throat irritation.

Example 5

Aerosol-generating articles were prepared.

A reference aerosol-generating article was prepared which comprised a filter element made from cellulose acetate and an aerosol-generating substrate comprising cut-filler.

Sample 1 was prepared which included a filter element formed from a cellulosic nonwoven material and an aerosol-generating substrate comprising cut-filler.

Sample 2 was prepared which contained a filter element formed from a cellulose-based paper material and an aerosol-generating substrate comprising cut-filler.

Sample 3 was prepared which comprised a filter element made from the same cellulose- based paper material as Sample 2, and an aerosol-generating substrate comprising cut-filler and lactic acid. Lactic acid was included in the substrate at 0.15 % (1.5 kg lactic acid/1 ton of tobacco applied at bright casing stage).

Each of the aerosol-generating articles were tested for their sensory properties by a panel. Around 108 panellists tested the reference sample, 110 panellists tested Sample 1 , 107 panellists tested Sample 2, and 110 panellists tested Sample 3.

Sample 3 was found to have an improved overall experience and improved overall taste profile compared to Samples 1 and 2. Sample 3 was found to have an improved experience and taste profile in some aspects compared to the reference sample, which comprised cut filler and a conventional cellulose acetate filter.

Sample 3 was assessed to have a very satisfying taste experience, the article was of high quality, it had a very pleasant aroma, and there was an improved balance in taste and an improved aftertaste, indicating that there was a reduction in sensorial harshness felt from the aerosol generated by Sample 3.

Sample 3, comprising a cellulose-based paper filter and a harshness-reduction agent, may advantageously generate an inhalable aerosol having an improved taste profile, reduced sensorial harshness and has a reduced environmental impact.

For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term "about". Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number A is understood as A ± 10% of A. Within this context, a number A may be considered to include numerical values that are within general standard error for the measurement of the property that the number A modifies. The number A, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which A deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

Claims

1. An aerosol-generating substrate for use in an aerosol-generating system, the aerosolgenerating substrate comprising: a cut filler comprising shredded plant material, an aerosol former, and a harshness-reduction agent, wherein the harshness-reduction agent consists of a carboxylic acid, wherein the carboxylic acid has a vapor pressure of from 0.001 to 1.00 Torr at 25 degrees Celsius.

2. The aerosol-generating substrate according to any claim 1 , wherein the pKa of the carboxylic acid is of from 3.20 to 5.50 in water at 25 degrees Celsius.

3. The aerosol-generating substrate according to any of claims 1 to 2, wherein the boiling point of the carboxylic acid is of from 150 to 310 degrees Celsius.

4. The aerosol-generating substrate according to any of claims 1 to 3, wherein the aerosolgenerating substrate is stable to thermal decarboxylation at temperatures of less than or equal to 300 degrees Celsius.

5. The aerosol-generating substrate according to any of claims 1 to 4, wherein the carboxylic acid has a chain length of from 3 to 8 carbon atoms.

6. The aerosol-generating substrate according to any of claims 1 to 5, wherein the carboxylic acid is selected from lactic acid, levulinic acid, succinic acid, crotonic acid, sorbic acid, trans-2-hexenoic acid, 3-hexenoic acid, 2-ethylbutyric acid, hexanoic acid, benzoic acid, 5-methyl-2-fuoric acid and cyclohexane carboxylic acid.

7. The aerosol-generating substrate according to any of claims 1 to 6, wherein the carboxylic acid is lactic acid.

8. The aerosol-generating substrate according to any of claims 1 to 7, wherein the carboxylic acid is present at 0.1 to 10 weight percent on a dry weight basis.

9. The aerosol-generating substrate according to any of claims 1 to 8, wherein the shredded plant-material comprises tobacco material.

10. The aerosol-generating substrate according to any of claims 1 to 9, wherein the aerosol former comprises or consists of propylene glycol, triethylene glycol, 1 ,3- butanediol, glycerine, glycerol monoacetate, glycerol diacetate, glycerol triacetate, dimethyl dodecanedioate, and dimethyl tetradecanedioate.

11 . The aerosol-generating substrate according to any one of claims 1 to 10, wherein the aerosol-generating substrate comprises the aerosol former in at least 10 percent by weight, on a dry weight basis, preferably at least 12 percent by weight of aerosol former, more preferably at least 15 percent by weight of aerosol former, on a dry weight basis.

12. The aerosol-generating substrate according to any of claims 1 to 11 , wherein the shredded-plant material is impregnated with aerosol-former.

13. A method of manufacturing the aerosol-generating substrate according to any of claims 1 to 12, wherein the method comprises: - providing a plant material;

- cutting the plant material to provide a shredded plant material, and

- performing a drying step to provide a cut-filler having a defined moisture level.

14. An aerosol-generating article for use in an aerosol-generating system, the aerosolgenerating article comprising the aerosol-generating substrate according to any of claims 1 to 12.

15. An aerosol-generating system comprising: an aerosol-generating article according to claim 14; and an aerosol-generating device configured to heat the aerosol-generating substrate of the aerosol-generating article.