WO2024068759A1

WO2024068759A1 - Flavour material with controlled thermal release for use in an aerosol-generating article

Info

Publication number: WO2024068759A1
Application number: PCT/EP2023/076757
Authority: WO
Inventors: Jérôme Jean-Yves GIRARD; Emmanuel Gérard René ROUGET
Original assignee: Philip Morris Products S.A.
Priority date: 2022-09-29
Filing date: 2023-09-27
Publication date: 2024-04-04

Abstract

A flavour material (50) for use in an aerosol-generating article, the flavour material comprising: a polysaccharide matrix structure; and a flavourant formulation dispersed within the polysaccharide matrix structure, wherein the aerosol-generating formulation is at least partly trapped within the polysaccharide matrix structure and releasable from the polysaccharide matrix structure upon heating of the flavour material. The flavour material comprises greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group and mixtures thereof. Also provided is an aerosol-generating article (10) comprising one such flavour material (50).

Description

FLAVOUR MATERIAL WITH CONTROLLED THERMAL RELEASE FOR USE IN AN AEROSOL-GENERATING ARTICLE

The present disclosure relates to a flavour material for use in an aerosol-generating article. Further, the present disclosure relates to aerosol-generating articles comprising one such flavour material.

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

Several aerosol-generating devices for consuming aerosol-generating articles have been disclosed in the art. Such devices include, for example, electrically heated aerosol-generating devices in which an aerosol is generated by the transfer of heat from one or more electrical heater elements of the aerosol-generating device to the aerosol-generating substrate of an aerosolgenerating article. For example, electrically heated aerosol-generating devices have been proposed that comprise an internal heater blade which is adapted to be inserted into the aerosolgenerating substrate. As an alternative, inductively heatable aerosol-generating articles comprising an aerosol-generating substrate and a susceptor arranged within the aerosolgenerating substrate have been proposed by WO 2015/176898.

It has been proposed to include in aerosol-generating articles a source of flavour in addition to the aerosol-generating substrate. In effect, this practice was relatively common with conventional filter cigarettes, and a number of solutions have been described in the art for providing a flavourant at a location in a mouthpiece filter or in the rod of tobacco cut filler.

However, given how the aerosol is generated and delivered to the consumer in aerosolgenerating articles, ensuring a consistent flavour delivery during use may be difficult, and so a consumer may perceive fluctuations or a decrease in flavour intensity over time. Additionally, even prior to the aerosol-generating articles being used, some flavour species may be lost during certain production steps or during transportation and storage of the aerosol-generating articles.

It has previously been proposed to reduce the loss of volatile flavourants from smoking conventional filter cigarettes during storage through the encapsulation of the flavourant, for example in the form of a capsule or microcapsule containing a flavourant formulation. The encapsulated flavour species can be released prior to or during smoking of the filter cigarette by breaking open the encapsulating structure, for example by manually crushing the structure. However, the encapsulated flavourant is typically released from the encapsulating structure in a single burst, and so one such solution might fail to provide a consistently intense flavour delivery during use of the article.

Therefore, a need is felt to provide flavour materials, as well as aerosol-generating articles containing flavour materials, that are associated with an enhanced flavour perception for the consumer, particularly towards the end of the use cycle of the aerosol-generating article.

The present disclosure relates to a flavour material for use in an aerosol-generating article, wherein a flavourant formulation is releasable from the flavour material upon heating the flavour material. The flavour material may comprise a matrix structure and a flavourant formulation dispersed within the matrix structure. The flavourant formulation is at least partly trapped within the matrix structure and is releasable from the matrix structure upon heating of the flavour material. The matrix structure may be a polysaccharide matrix structure. The flavour material may comprise greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof.

According to a first aspect of the present invention, there is provided a flavour material for use in an aerosol-generating article; the flavour material comprising: a polysaccharide matrix structure; and a flavourant formulation dispersed within the polysaccharide matrix structure. The flavourant formulation is at least partly trapped within the polysaccharide matrix structure and is releasable from the polysaccharide matrix structure upon heating of the flavour material. The flavour material comprises greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof.

As used herein with reference to the invention, the term “aerosol-generating article” is used to describe an article comprising an aerosol-generating substrate that is heated to generate an inhalable aerosol for delivery to a user.

As used herein with reference to the invention, 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 used herein with reference to the invention, 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 used herein with reference to the invention, the term “aerosol-generating device” is used to describe a device that interacts with the aerosol-generating substrate of the aerosolgenerating article to generate an aerosol.

Aerosol-generating articles according to the invention have a proximal end through which, in use, an aerosol exits the aerosol-generating article for delivery to a user. The proximal end of the aerosol-generating article may also be referred to as the downstream end or mouth end of the aerosol-generating article. In use, a user draws directly or indirectly on the proximal end of the aerosol-generating article in order to inhale an aerosol generated by the aerosol-generating article.

Aerosol-generating articles according to the invention have a distal end. The distal end is opposite the proximal end. The distal end of the aerosol-generating article may also be referred to as the upstream end of the aerosol-generating article.

Components of aerosol-generating articles according to the invention may be described as being upstream or downstream of one another based on their relative positions between the proximal end of the aerosol-generating article and the distal end of the aerosol-generating article.

As used herein with reference to the invention, the term “longitudinal” is used to describe the direction between the upstream end and the downstream end of the aerosol-generating article. During use, air is drawn through the aerosol-generating article in the longitudinal direction.

As used herein with reference to the invention, the term “length” is used to describe the maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in the longitudinal direction.

As used herein with reference to the invention, the term “transverse” is used to describe the direction perpendicular to the longitudinal direction. Unless otherwise stated, references to the “cross-section” of the aerosol-generating article or a component of the aerosol-generating article refer to the transverse cross-section.

As used herein with reference to the invention, the term “width” denotes the maximum dimension of the aerosol-generating article or a component of the aerosol-generating article in a transverse direction. Where the aerosol-generating article has a substantially circular crosssection, the width of the aerosol-generating article corresponds to the diameter of the aerosolgenerating article. Where a component of the aerosol-generating article has a substantially circular cross-section, the width of the component of the aerosol-generating article corresponds to the diameter of the component of the aerosol-generating article.

As used herein with reference to the invention, the term "hollow tubular element" is used to denote a generally cylindrical element having a lumen along a longitudinal axis thereof. The tubular portion may have a substantially circular, oval or elliptical cross-section. The lumen may have a substantially circular, oval or elliptical cross-section. In particular, the term "hollow tubular element" is used to denote an element defining at least one airflow conduit establishing an uninterrupted fluid communication between an upstream end of the hollow tubular element and a downstream end of the tubular element.

The inclusion of an additive selected from the group described above in flavour materials in accordance with the present invention has been found to have an impact on flavour release profile, in particular by facilitating and enhancing release of flavour at lower temperatures compared with flavour materials having substantially the same composition and structure, but containing no such additive.

Without wishing to be bound by theory, this effect is understood to be linked to the gaseous compounds released upon thermal decomposition of the additive. These gaseous compounds are thought to disrupt the polysaccharide matrix structure, presumably by breaking open some of the internal pockets within which the flavourant formulation is immobilised.

Thus, the improved release of flavour species afforded by flavour materials in accordance with the present invention may also allow a heater configured to supply heat to an aerosolgenerating article incorporating the flavour material to operate at a lower temperature and thus require less power during use.

By adjusting the content of additive or by selecting specific additives or both, it may advantageously be possible to further control the flavour release profile. In fact, including a larger amount of additive in the flavour material has been found to generally cause a more significant shift of the flavourant release profile towards lower temperatures.

Additionally, using different additives that undergo thermal decomposition at different temperatures, alone or in combination, may advantageously provide a tool for even more finely tuning the flavour release profile of the flavour material or of an aerosol-generating article containing the flavour material.

In general, it has been recognised that use of a flavour material in an aerosol-generating article, wherein an aerosol-generating substrate is meant to be heated to generate the aerosol, presents different challenges and poses different constraints, compared with conditions encountered in the past with conventional cigarettes, wherein a substrate is combusted to generate a smoke. The inventors have found that by adjusting the relative proportions of the various ingredients in the formulation or by altering the composition of the matrix - for example, by selecting certain combinations of polysaccharides to form the matrix - or by doing both, it may advantageously be possible to finely tailor certain characteristics of the flavour material to specific needs associated with use in an aerosol-generating article. For example, the flavour release profile may be adjusted, such as to have the flavour released in more successive “waves” during use. As a result, the consumer may perceive flavour notes as more intense or lingering for longer during use. Thus, flavour materials in accordance with the present invention may offer a wider breadth of flavour profiles that were not accessible with the known flavour materials.

When a flavour material in accordance with the invention is incorporated in an aerosolgenerating article, such as for example a heat-not-burn article configured to generate an aerosol upon heating a tobacco-containing aerosol-generating substrate, puff-by-puff flavour release has been found to be generally more efficient.

Because the flavourant formulation is at least partly trapped within the matrix until it is released upon heating, flavour materials in accordance with the present invention have been found to exhibit increased stability. For example, a significant reduction in losses of flavour species during storage, transportation, and so forth, has been observed, even under stress conditions. Coupled with the enhancement in flavour release at lower temperatures, this makes for a particularly efficient use of flavourants and other ingredients of the flavourant formulation.

As described briefly above, flavour materials in accordance with the present invention contain greater than 0.1 weight percent of an additive selected among polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof.

Preferably, the additive decomposes thermally at a pressure of 1 bar at a temperature of less than 220 degrees Celsius. More preferably, the additive decomposes thermally at a pressure of 1 bar at a temperature of less than 200 degrees Celsius. Even more preferably, the additive decomposes thermally at a pressure of 1 bar at a temperature of less than 180 degrees Celsius.

The additive may decompose thermally at a pressure of 1 bar at a temperature of at least 100 degrees Celsius, preferably at least 120 degrees Celsius, more preferably at least 140 degrees Celsius.

In some embodiments, the additive decomposes thermally at a pressure of 1 bar at a temperature from 100 degrees Celsius to 220 degrees Celsius, preferably from 120 degrees Celsius to 220 degrees Celsius, more preferably from 140 degrees Celsius to 220 degrees Celsius.

In other embodiments, the additive decomposes thermally at a pressure of 1 bar at a temperature from 100 degrees Celsius to 200 degrees Celsius, preferably from 120 degrees Celsius to 200 degrees Celsius, more preferably from 140 degrees Celsius to 200 degrees Celsius.

In further embodiments, the additive decomposes thermally at a pressure of 1 bar at a temperature from 100 degrees Celsius to 180 degrees Celsius, preferably from 120 degrees Celsius to 180 degrees Celsius, more preferably from 140 degrees Celsius to 180 degrees Celsius.

Use of one or more selected additives that decompose thermally at a pressure of 1 bar at temperatures in the ranges described above has been identified as especially beneficial because, upon heating a flavour material in accordance with the present invention, these additives begin to decompose thermally at temperatures that are significantly lower than the temperature at which the polysaccharide or polysaccharides forming the matrix decompose thermally. As a result, gaseous products generated upon thermal decomposition of the additive or additives get to interact with the matrix structure and may disrupt its integrity, such as by progressively breaking open a pocket or pockets of the matrix structure within which the flavourant formulation is trapped, and they may do so before the integrity of the matrix structure may be affected by the supply of heat alone.

For example, these additives may begin to decompose thermally at least 5 degrees Celsius below a temperature of thermal decomposition of the polysaccharide or polysaccharides forming the matrix structure. Preferably, these additives may begin to decompose thermally at least 10 degrees Celsius below a temperature of thermal decomposition of the polysaccharide or polysaccharides forming the matrix structure. More preferably, these additives may begin to decompose thermally at least 15 degrees Celsius below a temperature of thermal decomposition of the polysaccharide or polysaccharides forming the matrix structure. Even more preferably, these additives may begin to decompose thermally at least 20 degrees Celsius below a temperature of thermal decomposition of the polysaccharide or polysaccharides forming the matrix structure.

Polycarboxylic acids suitable for use as an additive in flavour materials in accordance with the present invention include, but are not limited to, tartronic acid, malonic acid.

Salts containing a hydrogencarbonate functional group suitable for use as an additive in flavour materials in accordance with the present invention include, but are not limited to, sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, ammonium hydrogencarbonate.

Preferably, the additive makes up for less than or equal to 25 percent by weight of the flavour material on a dry weight basis. More preferably, the additive makes up for less than or equal to 20 percent by weight of the flavour material on a dry weight basis. Even more preferably, the additive makes up for less than or equal to 15 percent by weight of the flavour material on a dry weight basis. In particularly preferred embodiments, the additive makes up for less than or equal to 10 percent by weight of the flavour material on a dry weight basis.

Preferably, the additive makes up for at least 0.25 percent by weight of the flavour material on a dry weight basis. More preferably, the additive makes up for at least 0.5 percent by weight of the flavour material on a dry weight basis. Even more preferably, the additive makes up for at least 1 .0 percent by weight of the flavour material on a dry weight basis.

In some embodiments, the additive makes up from 0.25 percent by weight to 25 percent by weight of the flavour material on a dry weight basis, preferably from 0.25 percent by weight to 20 percent by weight of the flavour material on a dry weight basis, more preferably from 0.25 percent by weight to 15 percent by weight of the flavour material on a dry weight basis, even more preferably from 0.25 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

In other embodiments, the additive makes up from 0.5 percent by weight to 25 percent by weight of the flavour material on a dry weight basis, preferably from 0.5 percent by weight to 20 percent by weight of the flavour material on a dry weight basis, more preferably from 0.5 percent by weight to 15 percent by weight of the flavour material on a dry weight basis, even more preferably from 0.5 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

In further embodiments, the additive makes up from 1.0 percent by weight to 25 percent by weight of the flavour material on a dry weight basis, preferably from 1.0 percent by weight to 20 percent by weight of the flavour material on a dry weight basis, more preferably from 1.0 percent by weight to 15 percent by weight of the flavour material on a dry weight basis, even more preferably from 1.0 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

In certain embodiments, the flavour material further comprises a carrier material. The polysaccharide matrix structure and the flavourant formulation trapped therein are supported by the carrier material.

This is advantageous in that the structural strength of the flavour material is improved by virtue of the carrier material serving a support function. This may be especially beneficial from a manufacturing viewpoint, as handling of the flavour material reinforced by the carrier material may generally be easier.

In some embodiments, the carrier material is a carrier sheet material. As used herein, the term “sheet material” denotes a laminar material having a width and length substantially greater than the thickness thereof. For example, the carrier material may be a sheet of homogenised tobacco material or a sheet of a paper material. Use of a homogenised tobacco material for manufacturing a flavour material in accordance with the present invention will be described in more detail below.

Embodiments wherein the carrier material is a carrier sheet material also have the advantage that the polysaccharide matrix structure and the flavourant formulation trapped therein may be deposited onto the carrier sheet material to form a flavour material that is, in effect, in sheet form as a whole and that can, as such, be cut into pieces having a predetermined average size (for example, a predetermined cut width or a predetermined cut length or both). This makes it easy to combine the flavour material with an aerosol-generating substrate in certain aerosolgenerating articles, as will be described in more detail below. In other embodiments, the carrier material may comprise a plurality of pieces cut from a sheet material, the pieces having a predetermined average size (for example, a predetermined cut width or a predetermined cut length or both). As an alternative, the carrier material may comprise a plurality of pieces cut from a naturally occurring plant material, preferably a plant leaf material (for example, tobacco lamina). In some embodiments, the carrier material may be tobacco cut filler.

In all the embodiments of the flavour material comprising a carrier material, the polysaccharide matrix structure trapping the flavourant formulation may be formed in situ on the carrier material. If this in situ formation step follows a manufacturing process from which the carrier material may is obtained, the in situ formation step may even be performed at a later date or at a different location.

Use of a carrier sheet material supporting polysaccharide matrix structure and the trapped flavourant formulation may have the added benefit that, by selecting and adjusting certain properties of the carrier sheet material (for example, its thickness) one may obtain a flavour material that is easier to form into a bobbin, and which can therefore be handled and processed more easily when the flavour material is incorporated into an aerosol-generating article. In view of a high speed automated manufacturing process, the increased structural strength provided by the carrier sheet material may be particularly beneficial.

As mentioned previously, in some preferred embodiments, the carrier sheet material may be in the form of a sheet of a homogenised tobacco material.

As used in the present specification, the term “homogenised tobacco material” encompasses any tobacco material formed by the agglomeration of particles of tobacco material. Sheets or webs of homogenised tobacco material are formed by agglomerating particulate tobacco obtained by grinding or otherwise powdering of one or both of tobacco leaf lamina and tobacco leaf stems. In addition, homogenised tobacco material may comprise a minor quantity of one or more of tobacco dust, tobacco fines, and other particulate tobacco by-products formed during the treating, handling and shipping of tobacco. The sheets of homogenised tobacco material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art.

Sheets or webs of homogenised tobacco material for use in the invention may have a tobacco content of at least about 40 percent by weight on a dry weight basis, more preferably of at least about 60 percent by weight on a dry weight basis, more preferably or at least about 70 percent by weight on a dry basis and most preferably at least about 90 percent by weight on a dry weight basis.

Sheets or webs of homogenised tobacco material for use as the carrier sheet material may comprise one or more intrinsic binders, that is tobacco endogenous binders, one or more extrinsic binders, that is tobacco exogenous binders, ora combination thereof to help agglomerate the particulate tobacco. Alternatively, or in addition, sheets of homogenised tobacco material for use as the carrier sheet material may comprise other additives including, but not limited to, tobacco and non-tobacco fibres, aerosol-formers, humectants, plasticisers, flavourants, fillers, aqueous and non-aqueous solvents and combinations thereof.

Suitable extrinsic binders for inclusion in sheets or webs of homogenised tobacco material for use as the carrier sheet material are known in the art and include, but are not limited to: gums such as, for example, guar gum, xanthan gum, arabic gum and locust bean gum; cellulosic binders such as, for example, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose and ethyl cellulose; polysaccharides such as, for example, starches, organic acids, such as alginic acid, conjugate base salts of organic acids, such as sodiumalginate, agar and pectins; and combinations thereof.

Suitable non-tobacco fibres for inclusion in sheets or webs of homogenised tobacco material for use as the carrier sheet material are known in the art and include, but are not limited to: cellulose fibres; soft-wood fibres; hard-wood fibres; jute fibres and combinations thereof. Prior to inclusion in sheets of homogenised tobacco material for use as the carrier sheet material, non- tobacco fibres may be treated by suitable processes known in the art including, but not limited to: mechanical pulping; refining; chemical pulping; bleaching; sulphate pulping; and combinations thereof.

Preferably, the sheets or webs of homogenised tobacco material comprise an aerosol former. As used herein, the term “aerosol former” describes any suitable known compound or mixture of compounds that, in use, facilitates formation of an aerosol and that is substantially resistant to thermal degradation at the operating temperature of the aerosol-generating article.

Suitable aerosol-formers are known in the art and include, but are not limited to: polyhydric alcohols, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and glycerine; esters of polyhydric alcohols, such as glycerol mono-, di- or triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such as dimethyl dodecanedioate and dimethyl tetradecanedioate.

Preferred aerosol formers are polyhydric alcohols or mixtures thereof, such as propylene glycol, triethylene glycol, 1 ,3-butanediol and, most preferred, glycerine.

The sheets or webs of homogenised tobacco material may comprise a single aerosol former. Alternatively, the sheets or webs of homogenised tobacco material may comprise a combination of two or more aerosol formers.

The sheets or webs of homogenised tobacco material have an aerosol former content of greater than 10 percent on a dry weight basis. Preferably, the sheets or webs of homogenised tobacco material have an aerosol former content of greater than 12 percent on a dry weight basis. More preferably, the sheets or webs of homogenised tobacco material have an aerosol former content of greater than 14 percent on a dry weight basis. Even more preferably the sheets or webs of homogenised tobacco material have an aerosol former content of greater than 16 percent on a dry weight basis.

The sheets of homogenised tobacco material may have an aerosol former content of between approximately 10 percent and approximately 30 percent on a dry weight basis. Preferably, the sheets or webs of homogenised tobacco material have an aerosol former content of less than 25 percent on a dry weight basis.

In a preferred embodiment, the sheets of homogenised tobacco material have an aerosol former content of approximately 20 percent on a dry weight basis.

Sheets or webs of homogenised tobacco for use as the carrier sheet material in the flavour material of the present invention may be made by methods known in the art, for example the methods disclosed in International patent application WO-A-2012/164009 A2. In a preferred embodiment, sheets of homogenised tobacco material for use as the carrier sheet material are formed from a slurry comprising particulate tobacco, guar gum, cellulose fibres and glycerine by a casting process.

In other embodiments, the carrier sheet material may be in the form of a sheet of a nontobacco aerosol-generating material. For example, the carrier sheet material may be a sheet of sorbent non-tobacco material loaded with nicotine (for example, in the form of a nicotine salt) and an aerosol-former. Examples of such rods are described in the international application WO-A- 2015/082652. In addition, or as an alternative, the carrier sheet material may be a sheet of a homogenised non-tobacco plant material, such as an aromatic non-tobacco plant material.

In certain embodiments, the carrier sheet material may be in the form of a paper wrapper material. This has the benefit that the flavour material may be used as an alternative or in addition to conventional paper wrapper materials in the manufacture of an aerosol-generating article. Thus, the flavour material may be incorporated into the aerosol-generating article without significantly altering existing manufacturing processes and without requiring significant modifications of existing manufacturing apparatus.

Preferably, the polysaccharide matrix structure comprises gellan gum and an emulsifier. The term “gellan gum” is used to identify a water-soluble anionic polysaccharide, which is produced by the bacterium Sphingomonas elodea. The repeating unit of the polymer is a tetrasaccharide, which consists of two residues of D-glucose and one of each residues of L- rhamnose and D-glucuronic acid. Gellan gum has been approved for food, non-food, cosmetic and pharmaceutical uses by authorities in many jurisdictions, such as Japan, USA, Canada, China, South Korea and the EU.

Two forms of gellan gum are known - namely, high acyl gellan gum and low acyl gellan gum - which differ by way of the degree/percent of substitution by O-acyl groups. In flavour materials in accordance with the present invention, the gellan gum is preferably low acyl gellan gum. This is a gellan gum that is partly deacylated or fully deacylated. Its most common form is the fully deacylated one, with no detectable acyl groups, which is also called deacetylated gellan gum.

Use of low acyl gellan gum to form the polysaccharide matrix of a flavour material in accordance with the present invention is preferred because low acyl gellan gum is capable of forming gels at very low concentrations. Additionally, the texture of gellan gum based gels varies with the acyl content, low acyl gellan gum typically forming firmer, less elastic and more brittle gels compared with high acyl gellan gum.

In embodiments wherein the polysaccharide matrix structure comprises gellan gum and an emulsifier, a flavour material may advantageously be provided wherein a substantial fraction of the flavourant formulation is effectively trapped within the polysaccharide matrix structure. This is beneficial in that it improves the stability of the flavour material. Further, as it will be discussed in more detail below, it has an impact on how flavour species are released upon heating the flavour material, and so it may help tune a flavourant release profile during use.

Additionally, from a manufacturing viewpoint, a stable polysaccharide matrix structure comprising gellan gum and an emulsifier can be formed by supplying heat to the starting reagents without requiring the use of cross-linking agents. In fact, by kneading and emulsifying the flavourant formulation and gellan gum in a heated aqueous bath, the polysaccharide-coated flavourant can be brought to an emulsified state which is then substantially preserved after drying and cooling. Advantageously, this allows for a significant amount of flavourant to be provided in an immobilised state within the polysaccharide matrix, and so a flavour material with a high flavourant content may be provided.

Preferably, the emulsifier is lecithin. Use of lecithin as the emulsifier is advantageous in that it is commonly available and generally recognised as being non-toxic. Like gellan gum, lecithin is commonly used in the food industry as an additive, and has been approved for such use by both the USA Food and Drug Administration and the EU authorities. As such, the pairing of gellan gum and lecithin is especially adapted to be included in a flavour material destined for human use.

Preferably, where the polysaccharide matrix comprises gellan gum and an emulsifier, the gellan gum makes up from 5 percent by weight to 99.9 percent by weight of the flavour material on a dry weight basis.

More preferably, the gellan gum makes up at least 7 percent by weight of the flavour material on a dry weight basis, even more preferably at least 10 percent by weight of the flavour material on a dry weight basis. The gellan gum preferably makes up for up to 80 percent by weight of the flavour material on a dry weight basis, more preferably up to 60 percent by weight of the flavour material on a dry weight basis, even more preferably up to 40 percent by weight of the flavour material on a dry weight basis, particularly preferably up to 30 percent by weight of the flavour material on a dry weight basis.

In some embodiments, the gellan gum makes up from 5 percent by weight to 80 percent by weight of the flavour material on a dry weight basis, preferably from 5 percent by weight to 60 percent by weight of the flavour material on a dry weight basis, more preferably from 5 percent by weight to 40 percent by weight of the flavour material on a dry weight basis, even more preferably from 5 percent by weight to 30 percent by weight of the flavour material on a dry weight basis.

In other embodiments, the gellan gum makes up from 10 percent by weight to 80 percent by weight of the flavour material on a dry weight basis, preferably from 10 percent by weight to 60 percent by weight of the flavour material on a dry weight basis, more preferably from 10 percent by weight to 40 percent by weight of the flavour material on a dry weight basis, even more preferably from 10 percent by weight to 30 percent by weight of the flavour material on a dry weight basis.

The emulsifier may make up from 0.01 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. Preferably, the emulsifier makes up from 0.02 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. More preferably, the emulsifier makes up from 0.05 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. Even more preferably, the emulsifier makes up from 0.1 percent by weight to 2 percent by weight of the flavour material on a dry weight basis.

In preferred embodiments, emulsifier is lecithin and makes up from 0.01 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. Preferably, lecithin makes up from 0.02 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. More preferably, lecithin makes up from 0.05 percent by weight to 2 percent by weight of the flavour material on a dry weight basis. Even more preferably, lecithin makes up from 0.1 percent by weight to 2 percent by weight of the flavour material on a dry weight basis.

In certain embodiments, the polysaccharide matrix structure comprises gellan gum as the sole polysaccharide.

In other embodiments, the polysaccharide matrix structure comprises gellan gum in combination with at least a further polysaccharide selected from the group consisting of guar, tamarind gum, sodium alginate, xanthan gum, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose. Flavour materials according to the invention wherein the polysaccharide matrix structure comprises gellan gum in combination with one or more of the polysaccharides listed above have been found to provide different flavourant release profiles upon heating. For example, in embodiments wherein the polysaccharide matrix structure comprises gellan gum in combination with another one of the polysaccharides listed above, a flavourant release profile characterised by two distinct peaks at two different temperatures has been observed. Without wishing to be bound by theory, it is hypothesised that this is due to a different strength of interaction between the flavourant and each polysaccharide in the matrix structure, and may also have to do with each polysaccharide undergoing thermal decomposition at slightly different temperatures.

Because different combinations of polysaccharides in the matrix structure will generally lead to slightly different flavourant release profiles when the flavour material is heated, embodiments wherein gellan gum is combined with one or more of the other polysaccharides listed above may advantageously be used to fine-tune the flavourant release during use of an aerosol-generating article containing the flavour material. Additionally, different flavour materials, each containing a polysaccharide matrix structure comprising a different combination of polysaccharides, may be used in combination in a single aerosol-generating article to further adjust and control flavourant delivery during a whole use cycle of the aerosol-generating article. For example, incorporating in a single aerosol-generating article different flavour materials according to the invention, wherein the different flavour materials are adapted to release most of the flavourant at different temperature or at different times during the use cycle may help maintain an overall flavour delivery substantially consistent throughout.

In embodiments of the flavour material wherein the matrix structure comprises gellan gum in combination with at least one of the additional polysaccharides listed above, the at least one additional polysaccharide may make up at least 0.01 percent by weight of the flavourant delivery material on a dry weight basis. Preferably, the at least one additional polysaccharide makes up at least 0.1 percent by weight of the flavourant delivery material on a dry weight basis. More preferably, the at least one additional polysaccharide makes up at least 1.0 percent by weight of the flavourant delivery material on a dry weight basis. Even more preferably, the at least one additional polysaccharide makes up at least 2.0 percent by weight of the flavourant delivery material on a dry weight basis. In particularly preferred embodiments, the at least one additional polysaccharide makes up at least 5 percent by weight of the flavourant delivery material on a dry weight basis.

In embodiments of the flavour material wherein the matrix structure comprises gellan gum in combination with at least one of the additional polysaccharides listed above, the at least one additional polysaccharide may make up 80 percent by weight or less of the flavourant delivery material on a dry weight basis. Preferably, the at least one additional polysaccharide makes up 35 percent by weight or less of the flavourant delivery material on a dry weight basis. More preferably, the at least one additional polysaccharide makes up 25 percent by weight or less of the flavourant delivery material on a dry weight basis. Even more preferably, the at least one additional polysaccharide makes up 15 percent by weight or less of the flavourant delivery material on a dry weight basis.

In some embodiments, the at least one additional polysaccharide makes up from 1.0 percent to 35 percent by weight or less of the flavourant delivery material on a dry weight basis, preferably from 2.0 percent to 35 percent by weight or less of the flavourant delivery material on a dry weight basis, more preferably from 5.0 percent to 35 percent by weight or less of the flavourant delivery material on a dry weight basis.

In other embodiments, the at least one additional polysaccharide makes up from 1.0 percent to 25 percent by weight or less of the flavourant delivery material on a dry weight basis, preferably from 2.0 percent to 25 percent by weight or less of the flavourant delivery material on a dry weight basis, more preferably from 5.0 percent to 25 percent by weight or less of the flavourant delivery material on a dry weight basis.

In further embodiments, the at least one additional polysaccharide makes up from 1.0 percent to 15 percent by weight or less of the flavourant delivery material on a dry weight basis, preferably from 2.0 percent to 15 percent by weight or less of the flavourant delivery material on a dry weight basis, more preferably from 5.0 percent to 15 percent by weight or less of the flavourant delivery material on a dry weight basis.

The flavour material may comprise at least 0.01 percent by weight of a flavourant on a dry weight basis. Preferably, the flavour material comprises at least 1 percent by weight of a flavourant on a dry weight basis. More preferably, the flavour material comprises at least 5 percent by weight of a flavourant on a dry weight basis. Even more preferably, the flavour material comprises at least 10 percent by weight of a flavourant on a dry weight basis.

In certain embodiments, the flavour material comprises at least 20 percent by weight of a flavourant on a dry weight basis, preferably at least 25 percent by weight of a flavourant on a dry weight basis, more preferably at least 30 percent by weight of a flavourant on a dry weight basis.

The flavour material may up to 90 percent by weight of a flavourant on a dry weight basis. Preferably, the flavour material may up to 85 percent by weight of a flavourant on a dry weight basis. More preferably, the flavour material may up to 80 percent by weight of a flavourant on a dry weight basis. Even more preferably, the flavour material may up to 75 percent by weight of a flavourant on a dry weight basis.

In certain preferred embodiments, the flavour material comprises from 20 percent by weight to 80 percent by weight of a flavourant on a dry weight basis, preferably from 25 percent by weight to 80 percent by weight of a flavourant on a dry weight basis, more preferably from 30 percent by weight to 80 percent by weight of a flavourant on a dry weight basis.

In other preferred embodiments, the flavour material comprises from 20 percent by weight to 75 percent by weight of a flavourant on a dry weight basis, preferably from 25 percent by weight to 75 percent by weight of a flavourant on a dry weight basis, more preferably from 30 percent by weight to 75 percent by weight of a flavourant on a dry weight basis.

Suitable flavourants for inclusion in the flavourant formulation of a flavour material in accordance with the present invention include, but are not limited to:

Suitable flavourants for inclusion in the flavourant formulation of a flavour material in accordance with the present invention include, but are not limited to, menthol, limonene, and eugenol.

Menthol is a monoterpenoid, which may be made synthetically or obtained from the oils of peppermint or other mints. It imparts minty, cool flavour notes.

Limonene is a cyclic monoterpene, and is typically found in the oil of citrus fruit peels. It is also a component of the aromatic resins of numerous coniferous and broadleaved trees. It imparts citrusy flavour notes.

Eugenol is an allyl chain-substituted guaiacol, and is commonly found in the essential oils of clove, nutmeg, cinnamon, basil and bay leaf. It imparts spicy, clove-like flavour notes.

The inventors have found that menthol and limonene can be fairly easily trapped and immobilised within the polysaccharide matrix, and so flavour materials containing a flavourant formulation containing menthol, limonene or mixtures thereof exhibit very good stability.

In preferred embodiments, the flavourant formulation comprises menthol.

The flavour material may comprise at least 0.01 percent by weight of a menthol on a dry weight basis. Preferably, the flavour material comprises at least 1 percent by weight of a menthol on a dry weight basis. More preferably, the flavour material comprises at least 5 percent by weight of a menthol on a dry weight basis. Even more preferably, the flavour material comprises at least 10 percent by weight of a menthol on a dry weight basis.

In certain embodiments, the flavour material comprises at least 20 percent by weight of a menthol on a dry weight basis, preferably at least 25 percent by weight of a menthol on a dry weight basis, more preferably at least 30 percent by weight of a menthol on a dry weight basis.

The flavour material may up to 90 percent by weight of a menthol on a dry weight basis. Preferably, the flavour material may up to 85 percent by weight of a menthol on a dry weight basis. More preferably, the flavour material may up to 80 percent by weight of a menthol on a dry weight basis. Even more preferably, the flavour material may up to 75 percent by weight of a menthol on a dry weight basis. In certain preferred embodiments, the flavour material comprises from 20 percent by weight to 80 percent by weight of a menthol on a dry weight basis, preferably from 25 percent by weight to 80 percent by weight of a menthol on a dry weight basis, more preferably from 30 percent by weight to 80 percent by weight of a menthol on a dry weight basis.

In other preferred embodiments, the flavour material comprises from 20 percent by weight to 75 percent by weight of a menthol on a dry weight basis, preferably from 25 percent by weight to 75 percent by weight of a menthol on a dry weight basis, more preferably from 30 percent by weight to 75 percent by weight of a menthol on a dry weight basis.

The flavourant formulation typically comprises a solvent into which the flavourant is at least partly dissolved. Suitable solvents for inclusion in the flavourant formulation of flavour materials in accordance with the present invention include, but are not limited to, water and glycerol.

The inventors have found that solubility of a flavourant in a given solvent may have an impact on how stably the flavourant is retained within the flavour material during storage of an aerosol-generating article containing the flavour material. In more detail, the inventors have found that a greater affinity between the flavourant and the solvent favourably impact stability.

The Hansen solubility parameters provide a model for estimating the mutual affinity in any given flavourant/solvent pairing.

The solubility parameter 5 - measured in MPa - is a function of parameters that are an indication of energy associated with dispersion forces between molecules (bd), intermolecular forces between molecules (b_p), and hydrogen bonds between molecules (bh), as expressed by the following formula: b² = (b_d)² + (b_p)² + (b_h)²

Parameters, bd, b_p, and bh may be regarded as coordinates for a point in a three- dimensional space (the Hansen space). The distance R_a between two molecules in the Hansen space provides an indication of the affinity between the two molecules, and is calculated based on the following formula:

(Ra)² = 4 (b_d2 - bdi)² + (b_p2 - b_pi)² + (b_h2 - b_hi)²

In general, it is understood that lower values of R_a indicate a higher affinity in a given flavourant/solvent pairing.

With reference to flavourant formulations for inclusion in a flavour material in accordance with the present invention, the inventors have looked at pairing flavourants with glycerol as the solvent. In doing so, they have identified a number of flavourant/glycerol pairings that display particularly good stability of the flavourant within the flavour material during storage.

Preferably, flavourant/glycerol pairings for inclusion in the flavourant formulations of flavour materials in accordance with the present invention have a R_a for the flavourant/glycerol pairing is less than or equal to 22 MPa. The inventors have found that this condition is regarded as being indicative of a particularly high affinity between the flavourant and glycerol, and so flavourant/glycerol pairings with such an R_a consistently lead to flavour material having a particularly good flavour stability during storage. On this basis, the inventors have found that preferred flavourant/glycerol pairings for inclusion in the flavourant formulations of flavour materials in accordance with the present invention include: d-limonene/glycerol, I- menthone/glycerol, (E)-citral/glycerol, decanal/glycerol, linalool/glycerol. In certain embodiments, the flavour material further comprises greater than 0.1 weight percent carbon particles, the carbon particles having a volume mean particle size of greater than 10 micrometres.

The inclusion of carbon based material - such as graphite, expanded graphite, graphene, etc. - in flavour materials in accordance with the present invention has been found to enhance flavour release, particularly at lower temperatures, with respect to flavour materials having comparable composition and structure, but lacking the carbon based material. Without wishing to be bound by theory, this is hypothesised to relate to an enhancement of the thermal conductivity of the flavour material, which may cause the flavourant formulation to be more promptly released from the polysaccharide matrix structure as a certain threshold temperature may be reached more quickly.

Thus, the carbon particles and the additive may work synergistically towards an enhancement of the release of flavour species at lower temperatures compared with a flavour material that does not contain either as well as compared with embodiments of the flavour material in accordance with the invention not including the carbon particles.

The improvement in flavour release is thought to be linked to a more even temperature distribution throughout the flavour material during use. With a greater proportion of the flavour material reaching a sufficiently high temperature to release flavour species from the matrix structure, a higher usage efficiency of the flavourant formulation is made possible.

The improved release of flavour species afforded by embodiments of the flavour material in accordance with the present invention including carbon particles as described above may also allow a heater configured to supply heat to an aerosol-generating article incorporating the flavour delivery material to operate at a lower temperature and thus require less power.

By adjusting the amount and size of the carbon particles within the ranges that will be described in more detail below, it may be possible to control and fine-tune the flavour release enhancement. For example, a relatively narrow particle size distribution may provide a flavour delivery material that is more homogenous in terms of thermal conductivity. This may mean that, during use, temperature gradients in the flavour delivery material provided in different portions of an aerosol-generating article that are exposed to the same heating profile are minimised.

Preferably, the carbon particles consist of one or more of: graphite particles, expanded graphite particles and graphene particles. In a preferred embodiment, the carbon particles consist of one or both of expanded graphite particles and graphene particles.

Advantageously, particles such as those listed above, particularly graphite and expanded graphite, may have a high thermal conductivity and a low density, and so they may be able to substantially improve the thermal conductivity of the flavour material without significantly increasing the density of the flavour material. This may be advantageous in that an increase in density may increase the weight, and therefore the transport costs, for a given volume of the flavour material itself. Equally, an increase in density may potentially have a proportional impact on transport costs when the flavour material is incorporated into an aerosol-generating article.

Additionally, particles such as those listed above have the benefit that they may be inductively heated, and so heat may be supplied directly within a flavour material in accordance with the present invention when the flavour material is exposed to an electromagnetic field generated by an induction coil.

Preferably, the carbon particles have a volume mean particle size from 30 micrometres to 150 micrometres.

As used herein, the term “volume mean particle size” may refer to a mean calculated using the equation below, where d[4,3] is the volume mean particle size and d is the particle size.

In other words, the volume mean particle size may refer to a mean calculated by dividing the sum of the particle sizes to the fourth power by the sum of the particle sizes to the third power.

Surprisingly, the inventors have found these relatively small particle size ranges to be particularly effective at increasing the thermal conductivity of a flavour material, particularly when the flavour material is in the form of or comprises a sheet. In addition, these relatively small particle sizes may advantageously result in a more homogeneous distribution of thermal conductivity, and in a sheet having a more even thickness than if larger particle sizes were used.

In embodiments wherein the carbon particles are comprised within a carrier sheet material supporting the polysaccharide structure trapping the flavourant formulation, it may also be easier to mix particles in this size range with the similarly sized particles used to manufacture the carrier sheet material, such as in the case of a sheet of homogenised tobacco material or other plant material. The carbon particles may have a particle size distribution having a D10 particle size, a D50 particle size, and a D90 particle size. In such a particle size distribution, 10% of the particles have a particle size which is less than or equal to the D10 particle size and 90% of the particles have a particle size which is less than or equal to the D90 particle size. The D50 particle size is the median particle size so 50% of the particles have a particle size which is less than or equal to the D50 particle size.

The D90 particle size may be less than or equal to 50, 40, 30, 25, 20, 15, 10, 8, 5, or 3 times the D10 particle size. The D90 particle size may be greater than or equal to 2, 3, 5 or 8 times the D10 particle size.

The D90 particle size may be between 3 and 50, 3 and 40, 3 and 30, 3 and 25, 3 and 20, 3 and 15, 3 and 10, 3 and 8, 3 and 5, 5 and 50, 5 and 40, 5 and 30, 5 and 25, 5 and 20, 5 and 15, 5 and 10, 5 and 8, 8 and 50, 8 and 40, 8 and 30, 8 and 25, 8 and 20, 8 and 15, 8 and 10, 10 and 50, 10 and 40, 10 and 30, 10 and 25, 10 and 20, 10 and 15, 15 and 50, 15 and 40, 15 and 30, 15 and 25, 15 and 20 times the D10 particle size.

Preferred particle size distributions may have a D90 particle size between 3 and 25, or 3 and 15, times the D10 particle size. Particularly preferred particle size distributions may have a D90 particle size between 5 and 20, or 5 and 10, times the D10 particle size.

In certain preferred embodiments, in a flavour material according to the present invention the carbon particles have a particle size distribution with a D90 particle size and a D10 particles size, and the D90 particle size is no more than 25 or 15 times the D10 particle size.

A compromise must be made in relation to the particle size distribution. A tighter particle size distribution may advantageously provide a more uniform thermal conductivity throughout the flavour material. This is because there will be less variation in particle size in different locations in the flavour material. This may advantageously allow for more efficient usage of the flavourant formulation throughout the flavour material. However, a tighter particle size distribution may disadvantageously be more difficult and expensive to achieve. The inventors have found that the particle size distributions described above may provide an optimal compromise between these two factors.

Desired D10 and D90 particle sizes may be obtained by sieving. Sieving may therefore be used to obtain a narrow particle size distribution where desired.

The D10 particle size of the carbon particles may be greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns. Each of the carbon particles may have a particle size of greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns.

The D10 particle size of the carbon particles may be less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns. Each of the carbon particles may have a particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns.

The D90 particle size of the carbon particles may be less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns. Each of the carbon particles may have a particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns.

The D90 particle size of the carbon particles may be greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns. Each of the carbon particles may have a particle size of greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns.

One or both of a D50 particle size and a volume mean particle size of the carbon particles may be greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns.

One or both of a D50 particle size and a volume mean particle size of the carbon particles may be less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns.

One or both of a D50 particle size and a volume mean particle size of the carbon particles may be between 1 and 1000, preferably between 10 and 200, more preferably between 30 and 150, or even more preferably between 50 and 75 microns. Alternatively, or in addition, each of the carbon particles may have a particle size of between 1 and 1000, preferably between 10 and 200, more preferably between 30 and 150, or even more preferably between 50 and 75 microns.

Surprisingly, the inventors have found these relatively small particle size ranges to be particularly effective at increasing the thermal conductivity of a flavour material in accordance with the present invention, particularly in those embodiments wherein the flavour material comprises a carrier sheet material supporting the polysaccharide matrix trapping the flavourant formulation. In addition, these relatively small particle sizes may advantageously result in a more homogeneous carrier sheet material in terms of thermal conductivity, and in a carrier sheet material having a more even thickness than if larger particle sizes were used. It may also be easier to mix particles in this size range with the similarly sized particles used in some manufacturing processes for forming the carrier sheet material.

The carbon particles may have a volume mean particle size of greater than or equal to 1 , 2, 3, 5, 10, 20, 30, 35, 50, 75, 100, 150, 200, 250, 500, or 900 microns.

It may be particularly preferable that the volume mean particle size of the carbon particles is greater than 10 microns.

The carbon particles may have a volume mean particle size of less than or equal to 1000, 900, 500, 200, 100, 150, 100, 75, 50, 35, 30, 20, 10, 5, 3 or 2 microns. The carbon particles may have a volume mean particle size of between 1 and 1000, 10 and 200, 30 and 150, or 50 and 75 microns. These volume mean particle size ranges may be particularly preferable where the flavour material comprises, or is in the form of, a sheet.

The carbon particles may have a volume mean particle size at least 2, 3, 5, 8, 10, 15, or 20 times the number mean particle size.

It may be particularly preferable that the thermally conductive particles are, or comprise, graphite particles.

The graphite particles may have a particle size distribution with a D10 particle size of between 5 and 20, for example 10 and 14, microns, for example around 12 microns. The graphite particles may have a particle size distribution with a D50 particle size of between 25 and 45 microns, for example around 35 microns. The graphite particles may have a particle size distribution with a D90 particle size of between 45 and 75 microns, for example around 55 microns. Advantageously, such particles are commercially available and have been found by the inventors to provide a significant increase in the thermal conductivity of flavour materials.

It may be particularly preferable that the thermally conductive particles are, or comprise, expanded graphite particles.

The expanded graphite particles may have a particle size distribution with a D10 particle size of between 5 and 20, for example 9 and 12, microns, for example around 10.5 microns. The expanded graphite particles may have a particle size distribution with a D50 particle size of between 15 and 25 microns, for example around 20 microns. The expanded graphite particles may have a particle size distribution with a D90 particle size of between 46 and 66 microns, for example around 56 microns. Advantageously, such particles are commercially available and have been found by the inventors to provide a significant increase in the thermal conductivity of flavour materials. The expanded graphite particles may also advantageously reduce the overall density of the flavour material.

Each of the carbon particles may have three mutually perpendicular dimensions. A largest dimension of these three dimensions may be no more than 10, 8, 5, 3, or 2 times larger than a smallest dimension of these three dimensions. A largest dimension of these three dimensions being no more than 10, 8, 5, 3, or 2 times larger than a second largest dimension of these three dimensions. Each of these three dimensions may be substantially equal. Each of the carbon particles may be substantially spherical.

The carbon particles may comprise at least 10, 20, 50, 100, 200, 500, or 1000 particles.

In a flavour material in accordance with the present invention, the carbon particles make up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis. In some embodiments, the flavour material further comprises a polyol having the formula CnH2n+20n.

The term “polyol” is used herein to describe an organic compound comprising two or more hydroxyl groups. Polyols containing two, three, and four hydroxyl groups may also be referred to as diols, triols, and tetrols, respectively.

Preferred polyols for inclusion in a flavour material in accordance with the present invention include glycerol, sorbitol, xylitol, mannitol, and erythritol.

The incorporation of a polyol in the flavour material has a beneficial effect on its pliability. This may make the flavour material easier to handle and given a predetermined form, which may facilitate its incorporation into an aerosol-generating article.

Preferably, in embodiments where the flavour material comprises a polyol as described above, the polyol makes up from 0.01 percent by weight to 20 percent by weight of the flavour material on a dry weight basis. More preferably, the polyol makes up from 0.01 percent by weight to 15 percent by weight of the flavour material on a dry weight basis. Even more preferably, the polyol makes up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

In some embodiments, the flavour material comprises fibres, preferably cellulose fibres. The incorporation of fibres, especially cellulose fibres, may advantageously improve the tensile strength of the flavour material, particularly when it is provided in sheet form. This facilitates the manufacturing process, both of the flavour material itself and of an aerosol-generating article including the flavour material. The benefit is felt especially in those embodiments wherein the polysaccharide matrix trapping the flavourant formulation is not supported by a carrier material.

In embodiments of the flavour material comprising cellulose fibres, the cellulose fibres may make up at least 0.01 percent by weight of the flavour material on a dry weight basis. Preferably, the cellulose fibres make up at least 0.05 percent by weight of the flavour material on a dry weight basis. More preferably, the cellulose fibres make up at least 0.5 percent by weight of the flavour material on a dry weight basis. Even more preferably, the cellulose fibres make up at least 1.0 percent by weight of the flavour material on a dry weight basis. In particularly preferred embodiments, the cellulose fibres make up at least 2.0 percent by weight of the flavour material on a dry weight basis.

The cellulose fibres may make up 10 percent by weight or less of the flavour material on a dry weight basis. Preferably, the cellulose fibres make up 8.0 percent by weight or less of the flavour material on a dry weight basis. More preferably, the cellulose fibres make up 7.0 percent by weight or less of the flavour material on a dry weight basis. Even more preferably, the cellulose fibres make up 5.0 percent by weight or less of the flavour material on a dry weight basis. In some embodiments, the fibres make up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis. Preferably, the fibres make up from 0.01 percent by weight to 8.0 percent by weight of the flavour material on a dry weight basis. More preferably, the fibres make up from 0.01 percent by weight to 7.0 percent by weight of the flavour material on a dry weight basis. Even more preferably, the fibres make up from 0.01 percent by weight to 5 percent by weight of the flavour material on a dry weight basis.

In other embodiments, the fibres make up from 1.0 percent by weight to 10 percent by weight of the flavour material on a dry weight basis. Preferably, the fibres make up from 1 .0 percent by weight to 8.0 percent by weight of the flavour material on a dry weight basis. More preferably, the fibres make up from 1 .0 percent by weight to 7.0 percent by weight of the flavour material on a dry weight basis. Even more preferably, the fibres make up from 1 .0 percent by weight to 5 percent by weight of the flavour material on a dry weight basis.

In further embodiments, the fibres make up from 2.0 percent by weight to 10 percent by weight of the flavour material on a dry weight basis. Preferably, the fibres make up from 2.0 percent by weight to 8.0 percent by weight of the flavour material on a dry weight basis. More preferably, the fibres make up from 2.0 percent by weight to 7.0 percent by weight of the flavour material on a dry weight basis. Even more preferably, the fibres make up from 2.0 percent by weight to 5 percent by weight of the flavour material on a dry weight basis.

In some embodiments, a flavour material in accordance with the present invention may comprise a salt of calcium or a salt of magnesium or both, such as calcium chloride or calcium lactate.

The provision of Ca²⁺ ions or Mg²⁺ ions or both may advantageously [ ANY BENEFIT? ]

In embodiments where the flavour material comprises a salt of calcium or a salt of magnesium or both, the salt or salts make up from 0.01 percent by weight to 10 percent by weight on a dry weight basis. Preferably, the salt or salts make up from 0.01 percent by weight to 5 percent by weight on a dry weight basis.

In embodiments where the flavour material comprises a citrate salt, the citrate salt makes up from 0.01 percent by weight to 5 percent by weight on a dry weight basis. Preferably, the citrate salt makes up from 0.01 percent by weight to 1 percent by weight on a dry weight basis.

A flavour material in accordance with the present invention may generally comprise water. This is because the flavour material will generally be manufactured by combining the various compounds described above in an aqueous bath. After drying, the water content will be reduced, but may generally be non-null.

Thus, a flavour material in accordance with the present invention may comprise from 0.01 percent by weight to 10 percent by weight of water, preferably from 0.01 percent by weight to 8 percent by weight of water, more preferably from 0.01 percent by weight to 6 percent by weight of water, even more preferably from 0.01 percent by weight to 4 percent by weight of water.

In some embodiments, the flavour material comprises from 0.5 percent by weight to 10 percent by weight of water, preferably from 0.01 percent by weight to 8 percent by weight of water, more preferably from 0.5 percent by weight to 6 percent by weight of water, even more preferably from 0.5 percent by weight to 4 percent by weight of water.

In other embodiments, the flavour material comprises from 1.0 percent by weight to 10 percent by weight of water, preferably from 1.0 percent by weight to 8 percent by weight of water, more preferably from 1.0 percent by weight to 6 percent by weight of water, even more preferably from 1 .0 percent by weight to 4 percent by weight of water.

In further embodiments, the flavour material comprises from 1.5 percent by weight to 10 percent by weight of water, preferably from 1.5 percent by weight to 8 percent by weight of water, more preferably from 1 .5 percent by weight to 6 percent by weight of water, even more preferably from 1 .5 percent by weight to 4 percent by weight of water.

Flavour materials in accordance with the present invention can be prepared by different routes.

A method of manufacturing a flavour material in accordance with the present invention may comprise a first step of preparing an aqueous composition comprising a flavourant formulation, a polysaccharide, an emulsifier, and an additive selected among polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof; a second step of casting the aqueous composition over a substantially flat support surface; a third step of letting the aqueous composition jellify on the support surface; a fourth step of drying the jellified aqueous composition. The dried flavour material may subsequently be removed from the support surface. The support surface may be a metallic plate.

Another method of manufacturing a flavour delivery in accordance with the present invention may comprise a first step of preparing an aqueous composition comprising a flavourant formulation, a polysaccharide, an emulsifier, and an additive selected among polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof; a second step of casting the aqueous composition over a carrier sheet material lying on a substantially flat support surface; a third step of letting the aqueous composition jellify on the carrier sheet material; a fourth step of drying the jellified aqueous composition and the carrier sheet material. The dried flavour material wherein the carrier sheet material supports a polysaccharide matrix trapping the flavourant formulation may subsequently be removed from the support surface.

A further method of manufacturing a flavour delivery in accordance with the present invention may comprise a first step of preparing an aqueous composition comprising a flavourant formulation, a polysaccharide, an emulsifier, and an additive selected among polycarboxylic acids, salts containing a hydrogencarbonate functional group, and mixtures thereof; a second step of spraying the aqueous composition over a carrier sheet material (for example, homogenised tobacco material) lying on a substantially flat support surface; a third step of letting the aqueous composition jellify on the carrier sheet material; a fourth step of drying the jellified aqueous composition and the carrier sheet material. The dried flavour material wherein the carrier sheet material supports a polysaccharide matrix trapping the flavourant formulation may subsequently be removed from the support surface.

The present disclosure relates to an aerosol-generating article comprising a flavour material, wherein a flavourant formulation is releasable from the flavour material upon heating the flavour material. The flavour material may comprise a matrix structure and a flavourant formulation dispersed within the matrix structure. The flavourant formulation is at least partly trapped within the matrix structure and is releasable from the matrix structure upon heating of the flavour material. The matrix structure may be a polysaccharide matrix structure. The flavour material may comprise greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group and mixtures thereof.

According to another aspect of the present invention, there is provided an aerosolgenerating article comprising a flavour material, wherein the flavourant is releasable from the flavour material upon heating the flavour-delivery material. The flavour material comprises a polysaccharide matrix structure; and a flavourant formulation dispersed within the polysaccharide matrix structure. The flavourant formulation is trapped within the polysaccharide matrix structure and releasable from the polysaccharide matrix structure upon heating of the flavour material. The flavour material comprises greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group and mixtures thereof.

As will be apparent from the foregoing description of flavour materials in accordance with the present invention, by incorporating one such flavour material in an aerosol-generating article it is advantageously possible to provide a new range of aerosol-generating articles capable of delivering flavour to a consumer in a more easily controlled manner. Additionally, because the flavourant formulation is at least partly trapped within the matrix until it is released when heat is supplied to the aerosol-generating article during use, losses of flavour species during storage and transportation of the aerosol-generating articles can be greatly reduced. Coupled with the enhancement in flavour release at lower temperatures, this makes for a particularly efficient use of flavourants and other ingredients of the flavourant formulation.

Aerosol-generating articles in accordance with the present invention have been found to provide a more efficient release of flavour species during use compared with corresponding aerosol-generating articles containing an equivalent flavour material not including an additive in line with the foregoing description.

In particular, in certain embodiments release of flavour species has been observed to remain consistently higher and to vary less significantly from one puff to the next.

In certain embodiments, in aerosol-generating articles in accordance with the present invention the flavour material further comprises a carrier sheet material, wherein the polysaccharide matrix structure and the flavourant formulation are supported by the carrier sheet material.

The carrier sheet material provides a support for the polysaccharide matrix structure trapping the flavourant formulation, and so by adjusting the composition and geometry of the carrier sheet material it may be possible to facilitate manufacturing of the aerosol-generating article.

In certain embodiments, the aerosol-generating article comprises a rod of aerosolgenerating substrate; a downstream section provided downstream of the rod of aerosolgenerating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article. The flavour material is provided in at least one of the rod of aerosol-generating substrate; the downstream section; and the optional upstream section.

Where the flavour material comprises a carrier sheet material as described above, the carrier sheet material may be a sheet of homogenised tobacco material. In those embodiments, the aerosol-generating article may comprise a rod of aerosol-generating substrate; a downstream section provided downstream of the rod of aerosol-generating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article; and the flavour material may be provided in the rod of aerosol-generating substrate.

Incorporation of a flavour material in accordance with the present invention in an aerosolgenerating article may be carried out according to one of several routes.

For example, pieces of the flavour material may be mixed with solid particles of an aerosolgenerating material, such as cut tobacco, to form the rod of aerosol-generating substrate of an aerosol-generating article.

As an alternative, or additionally, pieces of the flavour material may be provided at other locations within the aerosol-generating article, such as locations along the downstream section of the aerosol-generating article. The downstream section of the aerosol-generating article may comprise multiple components, and so the flavour material may be incorporated into any one of such components. As a further alternative, a flavour material comprising a carrier sheet material in the form of a paper wrapper may be used as a plug wrap for the rod of aerosol-generating article alone or in combination with another paper wrapper.

This list of possible arrangements is not meant to be exhaustive, and it will be apparent that different placements of a flavour material in an aerosol-generating article may be possible, provided that during use of the aerosol-generating article the flavour material is supplied with enough heat to release the flavourant formulation from the polysaccharide matrix.

An aerosol-generating article containing a flavour material in accordance with the present invention may be used in combination with an aerosol-generating device, such as a hand-held electrical heater configured to supply heat in a controlled manner to the aerosol-generating article. This is so, by heating the aerosol-generating substrate and the flavour material, a flavour-enriched aerosol can be delivered to a consumer.

As such, aerosol-generating articles according to the invention find particular application in aerosol-generating systems comprising an aerosol-generating device having a heating chamber into which the aerosol-generating article is received such that heat can be supplied to the aerosol-generating substrate. This may be achieved by providing one or more heating elements arranged about the periphery of the heating chamber, the one or more heating elements being heated resistively or inductively. Alternatively, this may also be achieved by way of a resistively heated blade-shaped component of the aerosol-generating device, which is inserted into the aerosol-generating substrate when the aerosol-generating article is inserted into the heating chamber.

According to yet another alternative, a susceptor element may be provided within the aerosol-generating substrate, and the aerosol-generating device may have an inductor for producing an alternating or fluctuating electromagnetic field. When the aerosol-generating article engages with the aerosol-generating device, the fluctuating electromagnetic field produced by the inductor induces a current in the susceptor element, causing the susceptor element to heat up. The electrically-operated aerosol-generating device may be capable of generating a fluctuating electromagnetic field having a magnetic field strength (H-field strength) of between 1 and 5 kilo amperes per metre (kA m), preferably between 2 and 3 kA/m, for example about 2.5 kA/m.

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 : A flavour material for use in an aerosol-generating article, the flavour material comprising: a polysaccharide matrix structure; a flavourant formulation dispersed within the polysaccharide matrix structure, wherein the flavourant formulation is at least partly trapped within the polysaccharide matrix structure and releasable from the polysaccharide matrix structure upon heating of the flavour material; and greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group and mixtures thereof.

Example Ex2: A flavour material according to Example Ex1 , wherein the additive decomposes thermally at 1 bar at a temperature of less than 220 degrees Celsius.

Example Ex 3: A flavour material according to Example Ex1 or Ex2, wherein the additive begins to decompose thermally at least 5 degrees Celsius below a temperature of thermal decomposition of a polysaccharide forming the matrix structure.

Example Ex4: A flavour material according to any one of Examples Ex1 to Ex3, wherein the additive comprises one or more of tartronic acid, malonic acid, citric acid, sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, ammonium hydrogencarbonate.

Example Ex5: A flavour material according to any one of the preceding Examples, wherein the additive makes up for less than or equal to 25 percent by weight of the flavour material on a dry weight basis.

Example Ex6: A flavour material according to any one of the preceding Examples, wherein the additive makes up for less than or equal to 10 percent by weight of the flavour material on a dry weight basis.

Example Ex7: A flavour material according to any one of the preceding Examples, wherein the additive makes up for at least 1 percent by weight of the flavour material on a dry weight basis.

Example Ex8: A flavour material according to any one of Examples Ex1 to Ex7 further comprising a carrier material, wherein the polysaccharide matrix structure, the flavourant formulation and the additive are supported by the carrier material.

Example Ex9: A flavour material according to any one of Examples Ex1 to Ex8, wherein the polysaccharide matrix structure comprises gellan gum as the sole polysaccharide or gellan gum in combination with at least a further polysaccharide selected from the group consisting of guar, tamarind gum, sodium alginate, xanthan gum, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose.

Example Ex10: A flavour material according to Example Ex 9, wherein the gellan gum makes up from 5 percent by weight to 99.9 percent by weight of the flavour material on a dry weight basis.

Example Ex11 : A flavour material according to any one of Examples Ex1 to Ex10, further comprising a polyol having the formula C_nH2n+2O_n.

Example Ex12: A flavour material according to Example Ex11 , wherein the polyol is selected from the group consisting of glycerol, sorbitol, xylitol, mannitol, and erythritol. Example Ex 13: A flavour material according to Example Ex11 or Ex2, wherein the polyol makes up from 0.01 percent by weight to 20 percent by weight of the flavour material on a dry weight basis.

Example Ex14: A flavour material according to any one of the preceding Examples further comprising greater than 0.1 weight percent carbon particles, the carbon particles having a volume mean particle size of greater than 10 micrometres.

Example Ex15: A flavour material according to Example 14, wherein the carbon particles consist of one or more of: graphite particles, expanded graphite particles and graphene particles.

Example Ex16: A flavour material according to Example Ex14 or Ex15, wherein the carbon particles have a volume mean particle size from 30 micrometres to 150 micrometres.

Example Ex17: A flavour material according to any one of Examples Ex14 to Ex16, wherein the carbon particles have a particle size distribution with a D90 particle size and a D10 particles size, wherein the D90 particle size is no more than 25 or 15 times the D10 particle size.

Example Ex18: A flavour material according to any one of Examples Ex14 to Ex17, wherein the carbon particles make up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

Example Ex19: A flavour material according to any one of the preceding Examples further comprising fibres.

Example Ex20: A flavour material according to Example 20, wherein the fibres make up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

Example Ex21 : A flavour material according to any one of the preceding Examples comprising from 0.01 percent by weight to 80 percent by weight of menthol.

Example Ex22: A flavour material according to any one of Examples Ex 8 to Ex 21 , wherein the carrier sheet material is a sheet of homogenised tobacco material.

Example Ex23 An aerosol-generating article comprising a flavour material according to any one of Examples Ex1 to Ex22.

Example Ex24: An aerosol-generating article according to Example Ex23 comprising: a rod of aerosol-generating substrate; a downstream section provided downstream of the rod of aerosol-generating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article; wherein the flavour material is provided in at least one of the rod of aerosol-generating substrate; the downstream section; and the optional upstream section.

Example Ex25: An aerosol-generating article according to Example Ex 23 when in accordance with any one of Examples Ex 8 to Ex22, wherein the carrier material is a sheet of homogenised tobacco material or tobacco cut filler; wherein the aerosol-generating article comprises a rod of aerosol-generating substrate; a downstream section provided downstream of the rod of aerosol-generating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article; wherein the flavour material is provided in the rod of aerosol-generating substrate.

Examples will now be further described with reference to the figures in which:

Figure 1 shows a schematic side cross-sectional view of an aerosol-generating article in accordance with the present invention comprising a flavour material in the rod of aerosolgenerating substrate; and

Figure 2 shows a scanning electron microscope image of the flavour material used in the aerosol-generating article of Figure 1 .

An aerosol-generating article 10 in accordance with the present invention is shown in Figure 1. The aerosol-generating article 10 shown in Figure 1 comprises a rod 12 of aerosol-generating substrate and a downstream section 14 at a location downstream of the rod 12 of aerosolgenerating substrate. Further, the aerosol-generating article 10 comprises an upstream section 16 at a location upstream of the rod 12 of aerosol-generating substrate.

A ventilation zone 60 is provided at a location downstream of the rod 12 of aerosolgenerating substrate.

In more detail, in the embodiment of Figure 1 , the downstream section 14 comprises a mouthpiece element 18 and a hollow section 20. The hollow section 20 comprises an aerosolcooling element 22 comprising a hollow tubular element and the ventilation zone 60, which comprises a plurality of openings formed through a wall of the hollow tubular element. The aerosol-cooling element 22 is positioned immediately downstream of the rod 12 of aerosolgenerating substrate. As shown in the drawing of Figure 1 , an upstream end of the aerosolcooling element 22 abuts a downstream end of the rod 12 of aerosol-generating substrate. The mouthpiece element 18 is positioned immediately downstream of the aerosol-cooling element 22. As shown in the drawing of Figure 1 , an upstream end of the mouthpiece element 18 abuts a downstream end of the aerosol-cooling element 22. The mouthpiece element 18 comprises a plug 24 of low-density filtration material.

The rod 12 comprises an aerosol-generating substrate in the form of a gathered sheet of homogenised tobacco material. However, other types of tobacco-containing substrate, such as a tobacco cut filler, can replace the gathered sheet of homogenised tobacco material.

The upstream section 16 comprises a cylindrical plug 26 of compressed and plasticised cellulose acetate circumscribed by a wrapper 28. The plug 26 of the upstream section 16 has a length of about 5 millimetres. Further, the aerosol-generating article comprises a flavour material 50. In more detail, a plurality of pieces of a flavour material in sheet form are dispersed within the rod 12. The flavour material 50 is of the type described in detail above.

Examples of suitable formulations for the flavour material 50 and processes for forming the flavour material 50 are set out below.

Preparation A - Flavour delivery material comprising a menthol formulation trapped in a gellan gum polysaccharide matrix + 5 percent by weight of additive

100 g of water are heated to about 60 degrees Celsius and 3.0 g of gellan gum are added to the water bath. The resulting mixture is homogenized and heated to a temperature in the range from 80 to 85 degrees Celsius and kept at this temperature for 5 minutes. The mixture is subseguently cooled down to a temperature in the range from 70 to 75 degrees Celsius and 0.1 g of lecithin, 1 .2 g of tartronic acid and 8.0 g of menthol are added to the mixture. The flavourcontaining mixture is homogenized for 3 minutes. Subseguently, the resulting agueous composition is cast on a metallic tray, left to jellify and dried in a still oven at 65 degrees Celsius. An additive-enriched flavour material in sheet form is obtained.

Preparation B - Flavour delivery material comprising a menthol formulation trapped in a gellan gum polysaccharide matrix + 10 percent by weight of additive

100 g of water are heated to about 60 degrees Celsius and 3.0 g of gellan gum are added to the water bath. The resulting mixture is homogenized and heated to a temperature in the range from 80 to 85 degrees Celsius and kept at this temperature for 5 minutes. The mixture is subseguently cooled down to a temperature in the range from 70 to 75 degrees Celsius and 0.1 g of lecithin, 2.4 g of tartronic acid and 8.0 g of menthol are added to the mixture. The flavourcontaining mixture is homogenized for 3 minutes. Subseguently, the resulting agueous composition is cast on a metallic tray, left to jellify and dried in a still oven at 65 degrees Celsius. An additive-enriched flavour material in sheet form is obtained.

Preparation C - Flavour delivery material comprising a menthol formulation trapped in a i gum polysaccharide matrix + 5 percent by weight of additive on a carrier sheet material

(homogenised tobacco material)

100 g of water are heated to about 60 degrees Celsius and 3.0 g of gellan gum are added to the water bath. The resulting mixture is homogenized and heated to a temperature in the range from 80 to 85 degrees Celsius and kept at this temperature for 5 minutes. The mixture is subseguently cooled down to a temperature in the range from 70 to 75 degrees Celsius and 0.1 g of lecithin, 1 .2 g of tartronic acid and 8.0 g of menthol are added to the mixture. The flavourcontaining mixture is homogenized for 3 minutes. Subseguently, the resulting agueous composition is cast on a on a sheet of homogenised tobacco material located on a metallic tray, left to jellify and dried in a still oven at 65 degrees Celsius. An additive-enriched flavour material comprising a layer of gellan gum matrix trapping the menthol formulation immobilised on the on a sheet of homogenised tobacco material is obtained.

Comparative Preparation - Flavour delivery material comprising a menthol formulation trapped in a gellan gum polysaccharide matrix free of additive

100 g of water are heated to about 60 degrees Celsius and 3.0 g of gellan gum are added to the water bath. The resulting mixture is homogenized and heated to a temperature in the range from 80 to 85 degrees Celsius and kept at this temperature for 5 minutes. The mixture is subseguently cooled down to a temperature in the range from 70 to 75 degrees Celsius and 0.1 g of lecithin and 8.0 g of menthol are added to the mixture. The flavour-containing mixture is homogenized for 3 minutes. Subseguently, the resulting agueous composition is cast on a metallic tray, left to jellify and dried in a still oven at 65 degrees Celsius. An additive-free flavour material in sheet form is obtained.

Preparation D - Aerosol-generating article comprising a flavour delivery material produced according to Preparation A

An amount of flavour delivery material produced according to Preparation A making up for an overall content of menthol of 5 mg was added to the rod of a commercially available aerosolgenerating article (HEET® by Philip Morris Products S.A.).

Morphologic characterisation

Figure 2 shows a SEM image of a flavour delivery material 150 produced in accordance with Preparation A embedded in a wax. It can be seen from the image that the internal structure of the flavour delivery material includes a matrix 52 with a plurality of small pockets 54 adapted to trap the flavour composition, the pockets 54 being dispersed through the matrix 52. The domains are relatively uniformly distributed through the material and are relatively consistent in size. The SEM technology does not allow for the additive to be distinguished from the remainder of the matrix structure, in which the additive is understood to be dispersed in a substantially homogenous manner.

Thermogravimetric analysis

The flavour release profile of the flavour material produced according to the Preparations above may be analysed in a thermogravimetric analysis (TGA). The TGA test is carried out using a thermogravimetric machine coupled to a mass spectrometer, or similar TGA eguipment. In the analysis the flavour material is heated from 25 degrees Celsius to 400 degrees Celsius in an inert nitrogen atmosphere with the temperature being increased at a rate of 15 degrees Celsius per minute and with an air flow of 60 ml per minute. As the temperature is increased, the release of menthol is assessed by detecting the menthol molecules by way of a specific ion representative of menthol. Data collected carrying out TGA tests on flavour materials in accordance with the invention can be compared with data collected carrying out an equivalent TGA test on the flavourant formulation alone (e.g. pure menthol). One such comparison may provide some information about release mechanisms and dynamics, which may be help fine tune a flavourant release profile when the flavour material is incorporated in an aerosol-generating article.

To provide a comparative reference, pure menthol in liquid form was also heated in the thermogravimetric analysis described above. Unimodal release of pure menthol was observed between 50 degrees Celsius and 166 degrees Celsius, with a maximum around 138 degrees Celsius.

The menthol release profile of flavour materials produced in accordance with Preparations A and B was compared with the menthol release profile of a flavour material produced in accordance with Comparative Preparation by plotting the cumulative amount of menthol released by each flavour material side by side.

The results of this comparison suggest that the inclusion of the additive in the flavour material tends to enhance the thermal release of menthol at lower temperatures. The Comparative Preparation flavour material began to release menthol significantly only above 230 degrees Celsius, almost all the menthol content having been released as temperature approached 300 degrees Celsius.

By contrast, the Preparation A flavour material, containing 5 percent by weight of tartronic acid, appeared to release a first fraction of its menthol content between 90 degrees Celsius and about 150 degrees Celsius, and a second fraction of its menthol content between 160 degrees and 250 degrees Celsius.

The preparation B flavour material, containing 10 percent by weight of tartronic acid, also appeared to begin to release menthol around 90 degrees Celsius, but went on to release the remainder of its menthol content at a significantly higher rate, most of the menthol having been released by the time the temperature reached about 180 degrees.

Interestingly enough, from a qualitative viewpoint, the cumulative menthol release profile of the preparation B flavour material was found to be similar to that of pure menthol, but shifted towards higher temperature by some 20 to 30 degrees Celsius. By contrast, the cumulative menthol release profile of the preparation A flavour material suggests a behaviour that is substantially in line with that of the preparation B flavour material at the lower temperature, whilst deviating from it at higher temperatures by providing a delayed and more gradual release of the remainder of the menthol. Without wishing to be bound by theory, this may indicate that larger amounts of additive (tartronic acid) in the flavour material can disrupt the matrix structure to such a large extent that at temperatures of 140 degrees or more the matrix structure does no longer immobilise the menthol. On the other hand, smaller amounts of additive (tartronic acid) induce some disruption of the matrix structure, whereby menthol release is initiated at lower temperature, yet some residual integrity of the matrix structure is preserved, and so some of the menthol remains immobilised until higher temperatures are reached.

This comparison between the menthol release profiles of flavour materials prepared according to Preparations A and B alongside the Comparative Preparation demonstrates that adjusting the amount of additive in the flavour material may help fine tune flavour delivery when the flavour material is incorporated in an aerosol-generating article. In particular, it may be possible to control at what temperature flavour release is initiated and around what temperature flavour release is maximised. Additionally, flavour materials which, like the ones prepared according to Preparations A and B, have different flavour release profiles when exposed to a same heating profile, may be combined in a single aerosol-generating articles to provide an even broader range of flavour delivery options to the consumer.

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 ± 5% 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 . A flavour material for use in an aerosol-generating article, the flavour material comprising: a polysaccharide matrix structure; a flavourant formulation dispersed within the polysaccharide matrix structure, wherein the flavourant formulation is at least partly trapped within the polysaccharide matrix structure and releasable from the polysaccharide matrix structure upon heating of the flavour material; and greater than 0.1 weight percent of an additive selected from the group consisting of polycarboxylic acids, salts containing a hydrogencarbonate functional group and mixtures thereof.

2. A flavour material according to claim 1 , wherein the additive decomposes thermally at 1 bar at a temperature of less than 220 degrees Celsius.

3. A flavour material according to claim 1 or 2, wherein the additive begins to decompose thermally at least 5 degrees Celsius below a temperature of thermal decomposition of a polysaccharide forming the matrix structure.

4. A flavour material according to any one of claims 1 to 3, wherein the additive comprises one or more of tartronic acid, malonic acid, citric acid, sodium hydrogencarbonate, potassium hydrogencarbonate, magnesium hydrogencarbonate, calcium hydrogencarbonate, ammonium hydrogencarbonate.

5. A flavour material according to any one of the preceding claims, wherein the additive makes up for less than or equal to 25 percent by weight of the flavour material on a dry weight basis, preferably wherein the additive makes up for less than or equal to 10 percent by weight of the flavour material on a dry weight basis or wherein the additive makes up for at least 1 percent by weight of the flavour material on a dry weight basis or both.

6. A flavour material according to any one of claims 1 to 5 further comprising a carrier material, wherein the polysaccharide matrix structure, the flavourant formulation and the additive are supported by the carrier material, the carrier material being preferably a sheet of homogenised tobacco material.

7. A flavour material according to any one of claims 1 to 6, wherein the polysaccharide matrix structure comprises gellan gum as the sole polysaccharide or gellan gum in combination with at least a further polysaccharide selected from the group consisting of guar, tamarind gum, sodium alginate, xanthan gum, sodium carboxymethyl cellulose, and hydroxypropyl methyl cellulose, wherein the gellan gum makes up from 5 percent by weight to 99.9 percent by weight of the flavour material on a dry weight basis.

8. A flavour material according to any one of claims 1 to 7, further comprising a polyol having the formula C_nH2n+2O_n, wherein the polyol is preferably selected from the group consisting of glycerol, sorbitol, xylitol, mannitol, and erythritol or wherein the polyol makes up 0.01 percent by weight to 20 percent by weight of the flavour material on a dry weight basis or both.

9. A flavour material according to any one of the preceding claims further comprising greater than 0.1 weight percent carbon particles, the carbon particles having a volume mean particle size of greater than 10 micrometres, preferably a volume mean particle size from 30 micrometres to 150 micrometres.

10. A flavour material according to claim 9, wherein the carbon particles consist of one or more of: graphite particles, expanded graphite particles and graphene particles, the carbon particles preferably making up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

11. A flavour material according to claim 9 or 10, wherein the carbon particles have a particle size distribution with a D90 particle size and a D10 particles size, wherein the D90 particle size is no more than 25 or 15 times the D10 particle size.

12. A flavour material according to any one of the preceding claims further comprising fibres, wherein the fibres preferably make up from 0.01 percent by weight to 10 percent by weight of the flavour material on a dry weight basis.

13. An aerosol-generating article comprising a flavour material according to any one of claims 1 to 12.

14. An aerosol-generating article according to claim 13 comprising: a rod of aerosolgenerating substrate; a downstream section provided downstream of the rod of aerosolgenerating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article; wherein the flavour material is provided in at least one of the rod of aerosol-generating substrate; the downstream section; and the optional upstream section.

15. An aerosol-generating article according to claim 13 when depending on any one of claims 6 to 12, wherein the carrier material is a sheet of homogenised tobacco material or tobacco cut filler; wherein the aerosol-generating article comprises a rod of aerosol-generating substrate; a downstream section provided downstream of the rod of aerosol-generating substrate and extending to a mouth end of the aerosol-generating article; optionally an upstream section provided downstream of the rod of aerosol-generating substrate and extending to a distal end of the aerosol-generating article; wherein the flavour material is provided in the rod of aerosolgenerating substrate.