US20210000158A1 - Aerosol-generating substrate comprising an oil additive - Google Patents

Abstract

A heated aerosol-generating article for producing an inhalable aerosol is provided, the article including a rod of aerosol-generating substrate formed of one or more sheets of a homogenised tobacco material, the material being formed of an agglomeration of particles of tobacco material and including between 1 percent and 10 percent by weight of a medium chain triglyceride oil, on a dry weight basis, the oil having a melting point below 18 degrees Celsius and including one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms, and the one or more sheets being selected from reconstituted tobacco sheet and cast leaf. A rod of aerosol-generating substrate, an aerosol-generating system, and a method of making a homogenised tobacco material for an aerosol-generating article are also provided.

Description

• The present invention relates to a heated aerosol-generating article and homogenised plant material for use in such an article. In particular, the invention relates to a homogenised tobacco material that is suitable for use in a heated aerosol-generating article, such as, for example, a “heat-not-burn” type smoking article.
• Aerosol-generating articles in which an aerosol-generating substrate, such as a tobacco-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.
• A number of prior art documents disclose aerosol-generating devices for consuming or smoking heated aerosol-generating articles. 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 a heated aerosol-generating article. One advantage of such electrically heated aerosol-generating devices is that they significantly reduce sidestream smoke.
• Homogenised tobacco material is frequently used in the production of tobacco products, including substrates for aerosol-generating articles. This homogenised tobacco material is typically manufactured from parts of the tobacco plant that are less suited for the production of cut filler, like, for example, tobacco stems or tobacco dust.
• The most commonly used forms of homogenised tobacco material are reconstituted tobacco sheet and cast leaf. The process to form homogenised tobacco material sheets commonly comprises a step in which tobacco dust and a binder are mixed to form a slurry. The slurry is then used to create a tobacco web. For example, a tobacco web may be formed by casting a viscous slurry onto a moving metal belt to produce so called cast leaf. Alternatively, a slurry with low viscosity and high water content can be used to create reconstituted tobacco in a process that resembles paper-making.
• The term “cast leaf” may be used, in particular, to denote a form of homogenised tobacco material formed by a casting process that is based on casting a slurry comprising tobacco particles (alone or in a mixture with other plant particles) and a binder (such as, for example, guar gum) onto a supportive surface, such as a belt conveyor, drying the slurry and removing the dried sheet from the supportive surface. An example of the casting or cast leaf process is described in, for example, U.S. Pat. No. 5,724,998 for making cast leaf tobacco. In a cast leaf process, particulate plant materials are produced by pulverizing, grinding, or comminuting parts of the plant. The particles produced from one or more plants are mixed with a liquid component, typically water, to form a slurry. Other components in the slurry may include additional fibres, a binder and an aerosol former. The particulate plant materials may be agglomerated in the presence of the binder. The slurry is cast onto a supportive surface and dried into a sheet of homogenised tobacco material.
• The tobacco particles may be in the form of a tobacco dust comprising particles having an average diameter of the order of 30 to 80 micrometres or 100 to 250 micrometres, depending on the desired sheet thickness and casting gap. The additional fibres may include particles of tobacco stem material, stalks or other tobacco plant material, and other cellulose-based fibres such as wood fibres having a low lignin content. The type and size of the fibre particles may be selected with a view to adjusting the tensile strength of the cast leaf. Further, alternative fibres, such as vegetable fibres including hemp and bamboo may be used either with the above fibres or in alternative to the above fibres.
• A suitable process for forming a sheet of reconstituted tobacco is the so-called paper-making process. In a first step of such process, a tobacco material (alone or in a mixture with another plant material) is mixed with water to form a dilute suspension comprising mostly of separate cellulose fibres. This first step may involve soaking and applying heat. The suspension has a lower viscosity and a higher water content than the slurry produced in the casting process. The suspension may then be separated into an insoluble portion containing solid fibrous components and a liquid or aqueous portion comprising soluble tobacco substances. The water remaining in the insoluble fibrous portion may be drained through a screen, acting as a sieve, such that a web of randomly interwoven fibres may be laid down. Water may be further removed from this web by pressing with rollers, sometimes aided by suction or vacuum. When most of the moisture has been removed, a generally flat, uniform sheet of tobacco fibres is achieved. The soluble tobacco substances that were removed from the sheet may be concentrated, and the concentrated tobacco substances may be added back to the sheet resulting in a sheet of homogenised tobacco material. This process, as described in U.S. Pat. No. 3,860,012, has been used with tobacco to make reconstituted tobacco products, also known as tobacco paper.
• Other known processes that can be applied to producing sheets of homogenised tobacco material are dough reconstitution processes of the type described in, for example, U.S. Pat. No. 3,894,544; and extrusion processes of the type described in, for example, in GB-A-983,928. Typically, the densities of homogenised tobacco materials produced by extrusion processes and dough reconstitution processes are greater than the densities of the homogenised tobacco materials produced by casting processes.
• In a heated aerosol-generating article, an aerosol-generating substrate is heated to a relatively low temperature, for example about 350 degrees Celsius, in order to form an inhalable aerosol. In order that an aerosol may be formed, the homogenised tobacco material preferably comprises high proportions of aerosol formers and humectants, such as glycerine or propylene glycol. The homogenised tobacco material also contains nicotine. Rods formed from homogenised tobacco material that are suitable for use as aerosol-generating substrates in heated aerosol-generating articles are disclosed in WO-A-2012/164009.
• To create an aerosol, aerosol formers must be released from the homogenised tobacco material. In order to be released, these aerosol formers must migrate from within the body of the homogenised tobacco material to surfaces of the homogenised tobacco material. Other volatile compounds, such as nicotine, must also migrate from within the body of the homogenised tobacco material to become entrained in the aerosol. It may be desirable to improve the efficiency and rate at which aerosol formers are released from a homogenised tobacco material on heating.
• The migration of aerosol formers and other volatile compounds within a homogenised tobacco material is limited by diffusion. One way to improve the efficiency and rate at which aerosol formers are released may be to increase the temperature that the homogenised tobacco material is heated to, thereby improving diffusion. This may be undesirable, however, as an increase in temperature may result in the evolution of undesirable compounds. An increase in temperature may also adversely affect physical properties of the aerosol that is formed, for example temperature of the aerosol or droplet size of the aerosol.
• Another way to improve the efficiency and rate at which aerosol formers and other volatile compounds are released on heating may be to increase the amount of surface area per unit volume of homogenised tobacco material. This may necessitate the use of thin sheets of homogenised tobacco material. Homogenised tobacco material lacks strength, however, due to a high concentration of aerosol formers. Thin sheets of homogenised tobacco material are extremely difficult to handle and process.
• It would be desirable to provide a homogenised plant material for an aerosol-generating article which provides an improved delivery of volatile compounds such as nicotine. It would be particularly desirable to provide such a homogenised plant material that provides an improved delivery of volatile compounds even at reducing operating temperatures. It would be further desirable to provide such a homogenised plant material that can be efficiently manufactured, without the need to significantly modify existing manufacturing processes and apparatus.
• According to a first aspect of the invention, there is provided a heated aerosol-generating article for producing an inhalable aerosol, the heated aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate is formed of one or more sheets of a homogenised tobacco material selected from reconstituted tobacco sheet and cast leaf, the homogenised tobacco material comprising at least 1 percent by weight of a medium chain triglyceride oil, on a dry weight basis. The medium chain triglyceride oil has a melting point below 18 degrees Celsius and comprises one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms.
• According to a second aspect of the invention there is provided a homogenised tobacco material for use as an aerosol-generating substrate in a heated aerosol-generating article according to the first aspect of the invention, the homogenised tobacco material comprising at least 1 percent by weight of a medium chain triglyceride oil, on a dry weight basis. The medium chain triglyceride oil has a melting point below 18 degrees Celsius and comprises one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms.
• According to a third aspect of the invention there is provided an aerosol-generating system comprising: an aerosol-generating device comprising a heating element; and an aerosol-generating article for use with the aerosol-generating device, the aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate is formed of one or more sheets of a homogenised tobacco material selected from reconstituted tobacco sheet and cast leaf, the homogenised tobacco material comprising at least 1 percent by weight of a medium chain triglyceride oil, on a dry weight basis. The medium chain triglyceride oil has a melting point below 18 degrees Celsius and comprises one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms.
• According to a fourth aspect of the invention there is provided a method of making a homogenised plant material according to the second aspect of the invention, the method comprising the steps of: forming a slurry comprising tobacco material, water and a medium chain triglyceride oil having a melting point below 18 degrees Celsius and comprising one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms; homogenising the slurry; and casting and drying the slurry to form the homogenised tobacco material. The method is carried out without any external heating of the slurry.
• Any references below to preferred features or aspects of the rod of aerosol-generating substrate of aerosol-generating articles according to the invention should be considered to be applicable to all aspects of the present invention.
• As used herein, the term “heated aerosol-generating article” refers to an aerosol-generating article for producing an aerosol comprising an aerosol-generating substrate that is intended to be heated rather than combusted in order to release volatile compounds that can form an aerosol.
• As used herein, the term “aerosol-generating substrate” refers to a substrate capable of releasing upon heating volatile compounds, which can form an aerosol. The aerosol generated from aerosol-generating substrates of aerosol-generating articles described herein may be visible or invisible and may include vapours (for example, fine particles of substances, which are in a gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours.
• As used herein, the term “rod” refers to a generally cylindrical element of substantially polygonal cross-section and preferably of circular, oval or elliptical cross-section. The term “sheet” is used herein to refer to a laminar element having a width and length substantially greater than the thickness thereof.
• As used herein, the term “homogenised tobacco material” encompasses any tobacco material formed by the agglomeration of particles of tobacco material, along or in a mixture with other plant material. For example, sheets or webs of homogenised tobacco material are formed by agglomerating particulate tobacco material 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 homogenised tobacco material may be produced by casting, extrusion, paper making processes or other any other suitable processes known in the art as has been described above.
• As used here, the term “medium chain triglyceride oil” is used to define an oil comprising one or more triglycerides, each triglyceride having two or three fatty acid chains having a chain length of between 6 and 12 carbon atoms. The fatty acid chains may therefore include one or more of caproic acid (C6), caprylic acid (C8), capric acid (C10) and lauric acid (C12). These can be present in the medium chain triglyceride oil in any combination and in any relative amounts, provided the required properties of the medium chain triglyceride oil are obtained. For each triglyceride within the medium triglyceride chain oil, the three fatty acid chains may have the same length as each other or a different length, provided at least two of the fatty acid chains has a chain length of between 6 and 12 carbon atoms. For each triglyceride, the three fatty acid chains may be identical, or two or more of the fatty acid chains may be different to each other. The triglycerides may individually be saturated or unsaturated.
• Certain natural oils, such as coconut oil and palm kernel oil, contain suitable medium chain triglycerides and the medium chain triglyceride oil used in the present invention may in some cases be a fraction of a natural oil.
• Any reference to a medium chain triglyceride oil in relation to the homogenised plant material of any of the aspects of the present invention should be assumed to be a reference to a medium chain triglyceride having the melting point and fatty acid chain length as defined above, unless stated otherwise.
• As used herein, the term “melting point” refers to the clear point or complete melting point of the medium chain triglyceride oil. This corresponds to the temperature, in degrees Celsius, at which the oil is fully liquid and completely clear with no solid particles remaining. Many methods known in the art can be used to measure the clear point melting point of an oil, for example, the capillary technique or Stuart SMP50 melting point apparatus.
• As described above, the aerosol-generating article of the present invention incorporates an aerosol-generating substrate formed of one or more sheets of a homogenised tobacco material selected from reconstituted tobacco sheet and cast leaf, the homogenised tobacco material comprising an oil additive in the form of a medium chain triglyceride oil having a melting point below 18 degrees Celsius. The melting point of the medium chain triglyceride oil is such that the oil is always in a completely liquid form at room temperature (approximately 22 degrees Celsius). The homogenised tobacco material therefore includes oil in a liquid form dispersed within a solid matrix of the tobacco material.
• The diffusivity of volatile components, such as aerosol formers and nicotine, is greater in a liquid phase than in a solid phase. The liquid medium chain triglyceride oil will therefore act to facilitate the transfer of volatile components within the homogenised tobacco material to its surface. As such, the transfer of these volatile components from the homogenised tobacco material to an aerosol may be enhanced in comparison with a homogenised tobacco material that does not contain the liquid medium chain triglyceride oil. The medium chain triglyceride oil is preferably evenly distributed throughout the homogenised tobacco material, which means that at room temperature there are no separately distinguishable regions of oil and plant material. Rather, the oil and particles are fully homogenised.
• Homogenised tobacco material is one of the most expensive elements of a heated aerosol-generating article. The use of a homogenised tobacco material having a medium chain triglyceride oil incorporated into it, as described herein, may allow less tobacco to be used whilst providing an equivalent nicotine or aerosol yield compared to use of a homogenised tobacco material without a medium chain triglyceride oil as defined. This may provide cost savings whilst still providing the consumer with an equivalent experience.
• The use of a homogenised tobacco material having a medium chain triglyceride oil incorporated into it may also provide an increased nicotine or aerosol yield compared to a homogenised tobacco material having the same amount of tobacco but without a medium chain triglyceride oil as defined.
• The use of a homogenised tobacco material having a medium chain triglyceride oil incorporated into it, as described herein, may allow equivalent nicotine or aerosol yields at a lower temperature compared to the use of a homogenised tobacco material without a medium chain triglyceride oil as defined. In fact, it has been surprisingly found that the use of a homogenised tobacco material with a medium chain triglyceride as defined herein may provide a higher nicotine or aerosol yield at a lower temperature than is provided by the same material at a higher temperature.
• The potential use of a lower operating temperature may provide a number of benefits. For example, a lower temperature of operation may allow for longer periods of use without the need to recharge a battery. As a further example, a lower temperature of operation may allow for use of a smaller battery. As a further example, a lower temperature of operation may reduce the liberation of undesirable aerosol constituents from the homogenised tobacco material.
• It has also advantageously been found that the improvements in the delivery of nicotine and aerosol can be provided with a relatively low proportion of the medium chain triglyceride oil in the homogenised tobacco material, as described in more detail below. The medium chain triglyceride oil can therefore be incorporated into the homogenised tobacco material without significantly impacting the amounts of other components, such as tobacco and aerosol former, within the homogenised tobacco material.
• The use of a medium chain triglyceride oil having a melting point below 18 degrees Celsius such that the oil is liquid at room temperature also provides advantages in the manufacture of the homogenised tobacco material. In particular, the incorporation of the medium chain triglyceride oil into the homogenised tobacco material is facilitated, since the oil does not need to be heated in order to melt it and the slurry from which the homogenised tobacco material is formed does not need to be heated in order to retain the oil in liquid form. The manufacturing process can therefore be carried out without the need for external heating. This minimises the energy costs of the manufacturing process and also makes the process easier to carry out and to control. Furthermore, the absence of any external heating during the process of manufacturing the homogenised tobacco material ensures that the loss of volatile components from the tobacco material can be minimised.
• The use of a medium chain triglyceride as defined has also been found to reduce the stickiness of the homogenised tobacco material. Typically, sheets of homogenised tobacco material can become relatively sticky. This is a potentially big problem in relation to the storage of the homogenised tobacco material, since the stickiness makes the material difficult to handle. In particular, after storage of the homogenised tobacco material wound onto bobbins, the stickiness of the material makes it difficult to unwind it from the bobbins since the material will tend to stick to itself and the bobbins. This potentially damages the sheets of homogenised tobacco material and also means that a significant proportion of the sheets cannot be used and are discarded as waste. The problem is typically found to worsen as the period of storage is increased.
• In contrast, it has been surprisingly been found that when a medium chain triglyceride oil as defined is included in the homogenised tobacco material, the stickiness is considerably reduced so that the sheets become easier to handle. The proportion of the material that is wasted has therefore been found to be significantly lower where a medium chain triglyceride oil is incorporated, as in the present invention.
• The medium chain triglyceride oil included in the aerosol-generating substrate of aerosol-generating articles according to the present invention preferably has an iodine value of less than about 20, more preferably less than about 15, more preferably less than about 10, more preferably less than about 5 and most preferably of less than about 2.
• As used herein, the term “iodine value” characterises the degree of saturation in the medium chain triglyceride oil. The iodine value, also known as iodine number or iodine index, corresponds to the mass of iodine in grams that is consumed by 100 grams of the medium chain triglyceride oil as measured according to any iodometric techniques known in the art, such as treatment with Wijs solution, reaction with potassium chloride followed by titration with sodium thiosulfate. See for example, Firestone D (May-June 1994) “Determination of the iodine value of oils and fats: summary of collaborative study”. J AOAC Int. 77 (3): 674-6. The lower the iodine number, the fewer the carbon double bonds are present in the medium chain triglyceride oil and therefore the higher the degree of saturation.
• The low iodine value of the medium chain triglyceride oil in preferred embodiments of the present invention indicates that the oil has a very high degree of saturation. Preferably, the medium chain triglyceride oil is substantially fully saturated. The use of a medium chain triglyceride oil having a very high degree of saturation has been found to advantageously minimise the off-flavours that are generated when the oil is heated during use of the aerosol-generating article. The presence of the medium chain triglyceride oil within the aerosol-generating substrate therefore does not have an adverse effect on the flavour of the aerosol delivered to the consumer from the substrate. In contrast, oils having a lower degree of saturation and that are therefore more unsaturated, with a higher degree of carbon double bonds, will typically generate off-flavours upon heating that would be unacceptable to the consumer.
• Aerosol-generating articles according to the present invention are suitable for use in an aerosol-generating system comprising an electrically heated aerosol-generating device having an internal heater element for heating the aerosol-generating substrate. For example, aerosol-generating articles according to the invention find particular application in aerosol-generating systems comprising an electrically heated aerosol-generating device having an internal heater blade which is adapted to be inserted into the rod of aerosol-generating substrate. Aerosol-generating articles of this type are described in the prior art, for example, in European patent application EP-A-0 822 670.
• As used herein, the term “aerosol-generating device” refers to a device comprising a heater element that interacts with the aerosol-generating substrate of the aerosol-generating article to generate an aerosol.
• Alternatively, aerosol-generating article according to the invention may comprise a combustible carbon heat source for heating the aerosol-generating substrate during use. Aerosol-generating articles of this type are described in the prior art, for example, in International patent application WO-A-2009/022232.
• As described above, the aerosol-generating articles of the present invention include an aerosol-generating substrate comprising a homogenised plant material that has been modified to incorporate a medium chain triglyceride oil having specific properties. The medium chain triglyceride has a melting point below about 18 degrees Celsius, preferably below about 17 degrees Celsius, more preferably below about 16 degrees Celsius, more preferably below about 15 degrees Celsius, more preferably below about 14 degrees Celsius, more preferably below about 13 degrees Celsius, more preferably below about 12 degrees Celsius, more preferably below about 11 degrees Celsius and more preferably below about 10 degrees Celsius. In certain embodiments, the medium chain triglyceride oil may have a melting point below 5 degrees Celsius. In other embodiments, the medium chain triglyceride oil may have a melting point below 0 degrees Celsius. In all embodiments, the medium chain triglyceride oil is therefore liquid at room temperature, which provides the advantages discussed in detail above.
• The medium chain triglyceride oil comprises one or more medium chain triglycerides which have been selected to achieve the desired melting point, as defined above. The one or more medium chain triglycerides have at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms, more preferably between 6 and 10 carbon atoms and most preferably between 8 and 10 carbon atoms. Preferably, the one or more triglycerides have all three chains with a chain length of between 6 and 12 carbon atoms, more preferably between 6 and 10 carbon atoms and most preferably between 8 and 10 carbon atoms.
• Preferably, the medium chain triglyceride oil comprises at least 80 percent by weight triglycerides having at least two fatty acid chains with a chain length of between 8 and 10 carbon atoms. More preferably, the medium chain triglyceride oil comprises at least 90 percent by weight triglycerides having at least two fatty acid chains with a chain length of between 8 and 10 carbon atoms. Most preferably, the medium chain triglyceride oil comprises approximately 100 percent by weight triglycerides having at least two fatty acid chains with a chain length of between 8 and 10 carbon atoms.
• Preferably, in the medium chain triglyceride oil, the ratio of fatty acid chains with a chain length of 8 (C8) to fatty acid chains with a chain length of 10 carbon atoms (C10) is around 1:1. Where the medium chain triglyceride oil additionally includes fatty acid chains with a chain length of 12 carbon atoms (C12), the ratio of C8:C10:C12 is between about 1:1:6 and about 1:1:16.
• Suitable medium chain triglyceride oils for use in the present invention are commercially available. For example, a suitable medium chain triglyceride oil is Grindsted® MCT 60 X from Danisco. Grindsted® MCT 60 X corresponds to glyceryl tricaprylate-caprate, made from palm-derived caprylic/capric acid and natural glycerine of vegetable origin. It has a melting point significantly below 18 degrees and an iodine value of less than 0.5. Grindsted® MCT 60 X has a C8:C10:C12 ratio of approximately 1:1:16.
• The total content of the medium chain triglyceride oil in the homogenised tobacco material is at least about 1 percent by weight, preferably at least about 2 percent by weight, based on dry weight. Alternatively or in addition, the total content of the medium chain triglyceride oil in the homogenised tobacco material is preferably less than about 10 percent by weight, more preferably less than about 5 percent by weight, based on dry weight. For example, the total content of the medium chain triglyceride oil in the homogenised tobacco material may be between about 1 percent by weight and about 10 percent by weight, more preferably between about 1 percent and about 5 percent by weight, based on dry weight.
• The total content of medium chain triglyceride oil within a homogenised tobacco material can be quantitatively determined using a test method in which the homogenised tobacco material is first ground, then extracted in a liquid solvent and analysed using a liquid chromatography—mass spectrometry (LC-MS) technique to determine the nature of the triglycerides that are present in the extract. A detailed example of such a test method is provided in the example below.
• The homogenised tobacco material according to any aspect of the invention preferably comprises one or more aerosol formers. Functionally, an aerosol former is a component that can be volatilized and convey nicotine and/or flavouring in an aerosol when the homogenised tobacco material is heated above the specific volatilization temperature of the aerosol former. An aerosol former may be any suitable compound or mixture of compounds that, in use, facilitates formation of a dense and stable aerosol and is substantially resistant to thermal degradation at the operating temperature of the heated aerosol-generating article. Different aerosol formers vaporize at different temperatures. Thus, an aerosol former may be chosen based on its ability to remain stable at or around room temperature but volatize at a higher temperature, for example between 40-450 degrees Celsius.
• The aerosol former may also have humectant type properties that help maintain a desirable level of moisture in the homogenised tobacco material. In particular, some aerosol formers are hygroscopic materials that function as a humectant.
• Suitable aerosol formers for inclusion in homogenised plant material such as homogenised tobacco material are known in the art and include, but are not limited to: monohydric alcohols like menthol, polyhydric alcohols, such as 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, dimethyl tetradecanedioate, erythritol, 1,3-butylene glycol, tetraethylene glycol, triethyl citrate, propylene carbonate, Ethyl laurate, triacetin, meso-erythritol, a diacetin mixture, a diethyl suberate, triethyl citrate, benzyl benzoate, benzyl phenyl acetate, ethyl vanillate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene glycol.
• For homogenised tobacco materials intended for use in electrically-operated aerosol-generating system having a heating element, as described in more detail below, the aerosol former is preferably be glycerol (also known as glycerin or glycerine) or propylene glycol.
• The total content of aerosol former in the homogenised tobacco material is preferably between about 5 percent and about 30 percent by weight on a dry weight basis, more preferably between about 5 percent and about 20 percent by weight on a dry weight basis.
• The homogenised tobacco material preferably comprises at least about 70 percent by weight tobacco material, more preferably between about 70 percent and about 80 percent by weight tobacco material, on a dry weight basis. The tobacco material is preferably in the form of a ground tobacco powder. For example, the tobacco material may be ground to form a powder having a specified particle size. The homogenised tobacco material may contain tobacco powder having a mean power particle size of between about 0.03 millimetres and about 0.12 millimetres, for example, between about 0.05 millimetres and about 0.10 millimetres.
• The homogenised tobacco material preferably comprises tobacco material, in the form of a ground tobacco powder. As used herein with reference to the invention, the term “tobacco material” describes any material comprising tobacco, including, but not limited to, tobacco leaf, tobacco rib, tobacco stem, tobacco stalk, tobacco dust, expanded tobacco, reconstituted tobacco material and homogenised tobacco material. Alternatively or in addition, the homogenised tobacco material may comprise non-tobacco plant material, such as for example, tea or a herb such as peppermint.
• The homogenised tobacco material according to any aspect may further comprise one or more binders. Preferably, the total content of binder in the homogenised tobacco material is between about 1 percent and about 5 percent by weight on a dry weight basis. In the case of homogenised tobacco at least, there is a practical limit to the amount of binder that may be present in a tobacco slurry and hence in a homogenised tobacco material formed by casting the slurry.
• This is due to the tendency of the binders to gel when coming in contact with water. Gelling strongly influences the viscosity of the tobacco slurry, which in turn is an important parameter of the slurry for subsequent web manufacturing processes, like for example casting. It is therefore preferred to have a relatively low amount of binder in the homogenised tobacco material. The binder may help ensure that tobacco material, for example tobacco powder, remains substantially dispersed throughout the homogenised tobacco material.
• Although any binder may be employed, preferred binders are natural pectins, such as fruit, citrus or tobacco pectins; guar gums, such as hydroxyethyl guar and hydroxypropyl guar; locust bean gums, such as hydroxyethyl and hydroxypropyl locust bean gum; alginate; starches, such as modified or derivitised starches; celluloses, such as methyl, ethyl, ethylhydroxymethyl and carboxymethyl cellulose; tamarind gum; dextran; pullalon; konjac flour; xanthan gum and the like. A particularly preferred binder is guar.
• In certain cases, a homogenised tobacco material comprising the components described above can lack the strength required for handling and processing to form an aerosol-generating substrate for a heated aerosol-generating article. This may particularly the case where the homogenised tobacco material contains a high proportion of aerosol former, or where the tobacco is in the form of a finely ground powder. In order to achieve a better strength, the homogenised tobacco material may contain one or more further components such as a binder and a reinforcement.
• Homogenised tobacco material according to any aspect of the present invention may further comprise reinforcement fibres. The reinforcement fibres may have a mean fibre length of between 0.2 mm and 4.0 mm. The reinforcement fibres may be cellulose fibres. In some embodiments, the homogenised tobacco material may contain between 1 weight percent and 15 weight percent of reinforcement fibres on a dry weight basis, for example between 1.5 weight percent and 10 weight percent of reinforcement fibres on a dry weight basis.
• The inclusion of fibres, such as cellulose fibres, in the homogenised tobacco material increases the tensile strength of the material. Therefore, adding reinforcement fibres may increase the resilience of a web of homogenised tobacco material. This supports a smooth manufacturing process and subsequent handling of the homogenised tobacco material during the manufacture of aerosol-generating articles. In turn, this can lead to an increase in production efficiency, cost efficiency, reproducibility and production speed of the manufacture of the aerosol-generating articles and other smoking articles.
• Cellulose fibres for inclusion in a homogenised tobacco material are known in the art and include, but are not limited to: soft-wood fibres, hard wood fibres, jute fibres, flax fibres, tobacco fibres and combination thereof. In addition to pulping, the cellulose fibres might be subjected to suitable processes such as refining, mechanical pulping, chemical pulping, bleaching, sulphate pulping and combination thereof.
• Fibres particles may include tobacco stem materials, stalks or other tobacco plant material. Preferably, cellulose-based fibres such as wood fibres comprise a low lignin content. Alternatively fibres, such as vegetable fibres, may be used either with the above fibres or in the alternative, including hemp and bamboo.
• One relevant factor to be considered for reinforcement fibres is the fibre length. Where the fibres are too short, the fibres would not contribute efficiently to the tensile strength of the resulting homogenised tobacco material. Where the fibres are too long, the fibres may impact the homogeneity of the homogenised tobacco material. The size of fibres in a homogenised tobacco material comprising tobacco powder having a mean size between about 0.03 millimetres and about 0.12 millimetres and a quantity of binder between about 1 percent and about 3 percent in dry weight of the slurry, is advantageously between about 0.2 millimetres and about 4 millimetres. Preferably, the mean size of the fibres is between about 1 millimetre and about 3 millimetres. Preferably, this further reduction is obtained by means of a refining step.
• In the present specification, the fibre “size” means the fibre length, that is, the fibre length in the dominant dimension of the fibre. Further, preferably, according to the invention, the amount of the fibres is comprised between about 1 percent and about 3 percent in dry weight basis of the total weight of the homogenised tobacco material. In the case of a homogenised tobacco material, fibres having a mean size between about 0.2 millimetres and about 4 millimetres do not significantly inhibit the release of substances from fine ground tobacco powder when the homogenised tobacco material is used as an aerosol generating substrate of an aerosol generating article. Reinforcement fibres may be introduced into a tobacco slurry, and consequently into the homogenised tobacco material, as loose fibres.
• Homogenised tobacco material according to any aspect may comprise reinforcement in the form of a continuous reinforcement incorporated in the homogenised tobacco material. A continuous reinforcement may be incorporated into a slurry of the tobacco material during formation of the homogenised tobacco material. The continuous reinforcement is preferably a porous reinforcement sheet.
• The reinforcement sheet should be sufficiently porous for the tobacco material slurry to permeate into the porous reinforcement sheet before the slurry dries, thereby incorporating the reinforcement sheet into the homogenised tobacco material. Preferably, the porous reinforcement sheet is encapsulated within dried homogenised slurry to form the homogenised tobacco material. The porous reinforcement sheet may alternatively be termed a porous reinforcement matrix. The porous reinforcement sheet may be a porous fibre sheet or a porous fibre matrix, such as a porous cellulose sheet or a paper sheet, or a porous woven fabric.
• A porous reinforcement sheet formed from cellulose may be a preferred continuous reinforcement material. However, other materials may be used. For example, the porous reinforcement sheet may be a sheet that can be described as a porous fibre sheet or porous fibre matrix. The fibres of the sheet may be formed from other polymer materials such as polyethylene, polyester, polyphenylene sulphide, or a polyolefin. The fibres may be natural materials such as cotton.
• The homogenised tobacco material according to any aspect may comprise water. The homogenised tobacco material according to any aspect may comprise flavourants such as menthol.
• As described above, the inclusion of the medium chain triglyceride oil as defined into a homogenised tobacco material for forming an aerosol-generating substrate of an aerosol-generating article has been found to provide a significant improvement in the delivery of aerosol and nicotine from the aerosol-generating substrate upon heating of the aerosol-generating substrate.
• Preferably, the medium chain triglyceride oil provides an increase of at least 10 percent by weight of nicotine during heating of the aerosol-generating substrate compared with an equivalent aerosol-generating substrate without the medium chain triglyceride oil, in which the medium chain triglyceride oil has been replaced by an equivalent weight amount of aerosol former. More preferably, the medium chain triglyceride oil provides an increase of at least 15 percent by weight of nicotine during heating of the aerosol-generating substrate compared with an equivalent aerosol-generating substrate without the medium chain triglyceride oil. For the purposes of such a comparison, aerosol-generating articles including the aerosol-generating substrate with and without the medium chain triglyceride oil are heated in a heating test as defined below.
• In the heating test, the aerosol-generating article is inserted into an aerosol-generating device comprising a heating element for heating the aerosol-generating substrate of the aerosol-generating article. The heating element is programmed to heat the aerosol-generating substrate to about 350 degrees Celsius for 360 seconds, to simulate normal use of the aerosol-generating article. During the heating of the aerosol-generating article, the aerosol-generating article is placed in a sealed glass vial so that the gas phase constituents released from the aerosol-generating article during heating are collected. A sample of the gas phase constituents collected within the vial is then removed and the concentration of the various triglycerides are determined using a test method as described above. A suitable aerosol-generating device for the heating test is the iQOS® heat-not-burn device from Philip Morris International, which is commercially available.
• It has additionally been found that the effect of the inclusion of the medium chain triglyceride oil as defined into the homogenised tobacco material is even more significant at reduced operating temperatures. For example, in an equivalent heating test to that described above but in which the heating element is programmed to heat the aerosol-generating substrate at 300 degrees Celsius for 360 seconds, the medium chain triglyceride oil preferably provides an increase of at least 20 percent by weight of nicotine during heating of the aerosol-generating substrate compared with an equivalent aerosol-generating substrate without the medium chain triglyceride oil.
• The homogenised tobacco material may take any suitable form within the aerosol-generating substrate. In certain preferred embodiments, the aerosol-generating substrate comprises a rod comprising a gathered sheet of homogenised tobacco material.
• As used herein with reference to the invention, the term “rod” denotes a generally cylindrical element of substantially circular, oval or elliptical cross-section.
• As used herein with reference to the invention, the term “sheet” describes a laminar element having a width and length substantially greater than the thickness thereof.
• As used herein with reference to the invention, the term “gathered” describes a sheet that is convoluted, folded, or otherwise compressed or constricted substantially transversely to the longitudinal axis of the aerosol-generating article.
• Advantageously, the aerosol-generating substrate comprises a gathered textured sheet of homogenised tobacco material. As used herein with reference to the invention, the term “textured sheet” describes a sheet that has been crimped, embossed, debossed, perforated or otherwise deformed.
• Use of a textured sheet of homogenised tobacco material may advantageously facilitate gathering of the sheet of homogenised tobacco material to form the aerosol-generating substrate.
• The aerosol-generating substrate may comprise a gathered textured sheet of homogenised tobacco material comprising a plurality of spaced-apart indentations, protrusions, perforations or any combination thereof.
• In certain preferred embodiments, the aerosol-generating substrate comprises a gathered crimped sheet of homogenised tobacco material. As used herein with reference to the invention, the term “crimped sheet” describes a sheet having a plurality of substantially parallel ridges or corrugations. Advantageously, when the aerosol-generating article has been assembled, the substantially parallel ridges or corrugations extend along or parallel to the longitudinal axis of the aerosol-generating article. This facilitates gathering of the crimped sheet of homogenised tobacco material to form the aerosol-generating substrate.
• However, it will be appreciated that crimped sheets of homogenised tobacco material for inclusion in the aerosol-generating substrates of aerosol-generating articles according to the invention may alternatively or in addition have a plurality of substantially parallel ridges or corrugations that are disposed at an acute or obtuse angle to the longitudinal axis of the aerosol-generating article when the aerosol-generating article has been assembled.
• Sheets of homogenised tobacco material for inclusion in the aerosol-generating substrates of aerosol-generating articles according to the invention preferably have a thickness of between about 100 micrometres and about 400 micrometres, more preferably between about 125 micrometres and about 350 micrometres, more preferably between about 150 micrometres and about 300 micrometres, more preferably between about 175 micrometres and about 275 micrometres, more preferably between about 200 micrometres and about 250 micrometres, most preferably about 215 micrometres.
• Preferably, the sheets of homogenised tobacco material have a basis weight of between about 150 grams per square metre (gsm) and about 250 grams per square metre (gsm), more preferably between about 170 gsm and about 220 gsm, more preferably between about 180 gsm and about 210 gsm, more preferably between about 195 gsm and about 205 gsm, more preferably about 200 gsm.
• The thickness of the sheets of homogenised tobacco material may be measured using any suitable apparatus, such as a high precision micrometer for soft material, for example L&W-250-F (2 kPa measuring pressure, 0-range) or equivalent. The thickness may be measured by using a stack consisting of a number of sheets and the measured value is then divided by the number of sheets, for example, a stack of three sheets may be measured. In order to measure the basis weight of the sheets of homogenised tobacco material, the weight of a defined size of the sheet may be measured using any suitable apparatus, such as a precision balance, for example Mettler Toledo XP205 (0.1 mg accuracy) or equivalent. The dimensions of the sheet may be measured using a precision ruler, for example Hirlinger 1/10 mm or equivalent. The basis weight can then be calculated in a conventional manner.
• As an alternative to the use of a gathered sheet of homogenised tobacco material, as described above, the aerosol-generating substrate may be formed of a plurality of strips or shreds of a sheet of homogenised tobacco material. For example, the aerosol-generating substrate may be formed of a plurality of shreds of homogenised tobacco material that are aligned in the longitudinal direction and have been brought together and wrapped to form a rod of aerosol-generating substrate.
• The shreds of homogenised tobacco material preferably have a length of between about 10 millimetres and about 20 millimetres, more preferably between about 12 millimetres and about 18 millimetres, more preferably between about 14 millimetres and about 16 millimetres, more preferably about 15 millimetres. Alternatively or in addition, the shreds of homogenised tobacco material preferably have a width of between about 0.4 millimetres and about 0.8 millimetres.
• Preferably, the density of the sheet of homogenised tobacco material from which the shreds are formed is between about 500 and about 1500 milligrams per cubic centimetre, more preferably between about 800 and about 1200 milligrams per cubic centimetre, more preferably between about 900 and about 1100 milligrams per cubic centimetre, and most preferably between about 900 and about 970 milligrams per cubic centimetre.
• Preferably, the bulk density of the shreds of homogenised tobacco material within the aerosol-generating substrate is between about 0.4 grams per cubic centimetre and about 0.8 grams per cubic centimetre, preferably between about 0.5 grams per cubic centimetre and about 0.7 grams per cubic centimetre and most preferably between about 0.65 grams per cubic centimetre and about 0.67 grams per cubic centimetre.
• As described above, the homogenised tobacco material may be formed by the casting of a slurry. Alternatively, the homogenised tobacco material may be formed by another suitable method, such as for example, an extrusion method.
• Preferably, the aerosol-generating substrate comprises a rod of the homogenised tobacco material circumscribed by a wrapper, wherein the wrapper is provided around and in contact with the homogenised tobacco material. The wrapper may be formed from any suitable sheet material that is capable of being wrapped around homogenised tobacco material to form an aerosol-generating substrate. The wrapper may be porous or non-porous. Preferably, the wrapper is a paper wrapper but the wrapper may alternatively be non-paper.
• The rod of aerosol-generating substrate preferably has an external diameter that is approximately equal to the external diameter of the aerosol-generating article.
• Preferably, the rod of aerosol-generating substrate has an external diameter of at least 5 millimetres. The rod of aerosol-generating substrate may have an external diameter of between about 5 millimetres and about 12 millimetres, for example of between about 5 millimetres and about 10 millimetres or of between about 6 millimetres and about 8 millimetres. In a preferred embodiment, the rod of aerosol-generating substrate has an external diameter of 7.2 millimetres, to within 10 percent.
• The rod of aerosol-generating substrate may have a length of between about 7 millimetres and about 15 mm. In one embodiment, the rod of aerosol-generating substrate may have a length of about 10 millimetres. In a preferred embodiment, the rod of aerosol-generating substrate has a length of about 12 millimetres.
• Preferably, the rod of aerosol-generating substrate has a substantially uniform cross-section along the length of the rod. Particularly preferably, the rod of aerosol-generating substrate has a substantially circular cross-section.
• The aerosol-generating articles according to the invention preferably comprise one or more elements in addition to the rod of aerosol-generating substrate, wherein the rod and the one or more elements are assembled within a substrate wrapper. For example, aerosol-generating articles according to the invention may further comprise at least one of: a mouthpiece, an aerosol-cooling element and a support element such as a hollow acetate tube. For example, in one preferred embodiment, an aerosol-generating article comprises, in linear sequential arrangement, a rod of aerosol-generating substrate as described above, a support element located immediately downstream of the aerosol-generating substrate, an aerosol-cooling element located downstream of the support element, and an outer wrapper circumscribing the rod, the support element and the aerosol-cooling element.
• Aerosol-generating systems according to the present invention comprise an aerosol-generating article as described in detail above in combination with an aerosol-generating device which is adapted to receive the upstream end of the aerosol-generating article during smoking. The aerosol-generating device comprises a heating element which is adapted to heat the aerosol-generating substrate in order to generate an aerosol during use. Preferably, the heating element is adapted to penetrate the aerosol-generating substrate when the aerosol-generating article is inserted into the aerosol-generating device.
• Preferably, the aerosol-generating device additionally comprise a housing, an electrical power supply connected to the heating element and a control element configured to control the supply of power from the power supply to the heating element.
• Suitable aerosol-generating devices for use in the aerosol-generating system of the present invention are described in WO-A-2013/098405.
• The homogenised tobacco material for forming the aerosol-generating substrate of aerosol-generating article according to the present invention, described in detail above, may be produced using a method according to the fourth aspect of the invention, as defined above. In a first step of the method according to the present invention, an homogenised slurry is formed comprising tobacco material, a medium chain triglyceride oil and water. The medium chain triglyceride oil has a melting point below 18 degrees Celsius and comprises one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 atoms. The medium chain triglyceride oil has an iodine value of less than 2. In a second step, the homogenised slurry is cast onto a moving belt. In a third step, the cast homogenised slurry is dried to form a sheet of homogenised tobacco material. The casting and drying steps may be carried out using conventional procedures.
• According to the present invention, all of the steps of the method are carried out without any external heating of the homogenised slurry. As described in more detail above, this is possible because the medium chain triglyceride oil is in liquid form at room temperature and so can readily be incorporated into the slurry without the need for heating of the oil.
• Other components for forming the homogenised tobacco material may be incorporated into the slurry as required, prior to the casting of the slurry. For example, the homogenised slurry may further comprise one or more of: an aerosol former, a binder and reinforcement fibres.
• After the drying of the sheet of homogenised tobacco material, the sheet may be wound onto bobbins for storage so that it can be used at a later time to form the rods of aerosol-generating substrate. As described above, when the sheet of homogenised tobacco material is subsequently unwound from the bobbins to form the rods of aerosol-generating substrate, a certain proportion of the homogenised tobacco material is wasted due to damage to the sheet. Preferably, the percentage of wastage of a homogenised tobacco material according to the invention incorporating medium chain triglyceride oil as defined is at least about 10 percent lower than the percentage of wastage of an equivalent homogenised tobacco material without the medium chain triglyceride oil, after storage of the homogenised tobacco material for 40 days, more preferably at least about 20 percent lower and most preferably at least about 30 percent lower.
• As described above, this reduced level of wastage appears to be an advantageous result of the reduced stickiness of the homogenised tobacco material when the medium chain triglyceride as defined is incorporated.
• The invention will now be further described, by way of example only, with reference to the accompanying drawings in which:
• FIG. 1 is a schematic cross-sectional view of an aerosol-generating article according to an embodiment of the invention;
• FIG. 2 is a schematic cross-sectional view of an aerosol-generating system comprising an aerosol-generating device and an aerosol generating article according to the embodiment illustrated inFIG. 1; and
• FIG. 3 is a schematic cross-sectional view of the electrically heated aerosol generating device ofFIG. 2.
• The aerosol-generatingarticle10 shown inFIG. 1 comprises four elements arranged in coaxial alignment: an aerosol-generatingsubstrate20, asupport element30, an aerosol-coolingelement40, and amouthpiece50. Each of the four elements is circumscribed by a corresponding plug wrap (not shown). These four elements are arranged sequentially and are circumscribed by anouter wrapper60 to form the aerosol-generatingarticle10. The aerosol-generating10 has a proximal or mouth end70, which a user inserts into his or her mouth during use, and a distal end80 located at the opposite end of the aerosol-generatingarticle10 to the mouth end70.
• In use air is drawn through the aerosol-generating article by a user from the distal end80 to the mouth end70. The distal end80 of the aerosol-generating article may also be described as the upstream end of the aerosol-generatingarticle10 and the mouth end70 of the aerosol-generatingarticle10 may also be described as the downstream end of the aerosol-generatingarticle10. Elements of the aerosol-generatingarticle10 located between the mouth end70 and the distal end80 can be described as being upstream of the mouth end70 or, alternatively, downstream of the distal end80.
• The aerosol-generatingsubstrate20 is located at the extreme distal or upstream end of the aerosol-generatingarticle10. In the embodiment illustrated inFIG. 1, aerosol-generatingsubstrate20 comprises a gathered sheet of crimped homogenised tobacco material circumscribed by a wrapper. The crimped sheet of homogenised tobacco material comprises glycerin as an aerosol former. The aerosol-generatingsubstrate20 also comprises at least 1 percent by weight of a medium chain triglyceride oil, based on the total dry weight of the aerosol-generatingsubstrate20. Suitable formulations for the homogenised tobacco material are provided in Table 1 below.
• Thesupport element30 is located immediately downstream of the aerosol-generatingsubstrate20 and abuts the aerosol-generatingsubstrate20. In the embodiment shown inFIG. 1, the support element is a hollow cellulose acetate tube. Thesupport element30 locates the aerosol-generatingsubstrate20 at the extreme distal end80 of the aerosol-generatingarticle10 so that it can be penetrated by a heating element of an aerosol-generating device. As described further below, thesupport element30 acts to prevent the aerosol-generatingsubstrate20 from being forced downstream within the aerosol-generatingarticle10 towards the aerosol-coolingelement40 when a heating element of an aerosol-generating device is inserted into the aerosol-generatingsubstrate20. Thesupport element30 also acts as a spacer to space the aerosol-coolingelement40 of the aerosol-generatingarticle10 from the aerosol-generatingsubstrate20.
• The aerosol-coolingelement40 is located immediately downstream of thesupport element30 and abuts thesupport element30. In use, volatile substances released from the aerosol-generatingsubstrate20 pass along the aerosol-coolingelement40 towards the mouth end70 of the aerosol-generatingarticle10. The volatile substances may cool within the aerosol-coolingelement40 to form an aerosol that is inhaled by the user. In the embodiment illustrated inFIG. 1, the aerosol-cooling element comprises a crimped and gathered sheet of polylactic acid circumscribed by a wrapper90. The crimped and gathered sheet of polylactic acid defines a plurality of longitudinal channels that extend along the length of the aerosol-coolingelement40.
• Themouthpiece50 is located immediately downstream of the aerosol-coolingelement40 and abuts the aerosol-coolingelement40. In the embodiment illustrated inFIG. 1, themouthpiece50 comprises a conventional cellulose acetate tow filter of low filtration efficiency.
• To assemble the aerosol-generatingarticle10, the four elements described above are aligned and tightly wrapped within theouter wrapper60. In the embodiment illustrated inFIG. 1, theouter wrapper60 is a conventional cigarette paper. As shown inFIG. 1, an optional row of perforations is provided in a region of theouter wrapper60 circumscribing thesupport element30 of the aerosol-generatingarticle10. A distal end portion of theouter wrapper60 of the aerosol-generatingarticle10 is circumscribed by a band of tipping paper (not shown).
• The aerosol-generatingarticle10 illustrated inFIG. 1 is designed to engage with an aerosol-generating device comprising a heating element in order to be consumed by a user. In use, the heating element of the aerosol-generating device heats the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10 to a sufficient temperature to form an aerosol, which is drawn downstream through the aerosol-generatingarticle10 and inhaled by the user.
• During the heating of the aerosol-generating substrate, the medium chain triglyceride in the aerosol-generating substrate acts to improve the nicotine emitted from the tobacco in the aerosol-generating substrate, as demonstrated in the example below.
• FIG. 2 illustrates a portion of an aerosol-generatingsystem100 comprising an aerosol-generatingdevice110 and an aerosol-generatingarticle10 according to the embodiment described above and illustrated inFIG. 1.
• The aerosol-generatingdevice110 comprises aheating element120. As shown inFIG. 2, theheating element120 is mounted within an aerosol-generating article receiving chamber of the aerosol-generatingdevice110. In use, the user inserts the aerosol-generatingarticle10 into the aerosol-generating article receiving chamber of the aerosol-generatingdevice110 such that theheating element120 is directly inserted into the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10 as shown inFIG. 2. In the embodiment shown inFIG. 2, theheating element120 of the aerosol-generatingdevice110 is a heater blade.
• The aerosol-generatingdevice110 comprises a power supply and electronics (shown inFIG. 3) that allow theheating element120 to be actuated. Such actuation may be manually operated or may occur automatically in response to a user drawing on an aerosol-generatingarticle10 inserted into the aerosol-generating article receiving chamber of the aerosol-generatingdevice110. A plurality of openings is provided in the aerosol-generating device to allow air to flow to the aerosol-generatingarticle10; the direction of air flow is illustrated by arrows inFIG. 2.
• Thesupport element40 of the aerosol-generatingarticle10 resists the penetration force experienced by the aerosol-generatingarticle10 during insertion of theheating element120 of the aerosol-generatingdevice110 into the aerosol-generatingsubstrate20. Thesupport element40 of the aerosol-generatingarticle10 thereby resists downstream movement of the aerosol-generatingsubstrate20 within the aerosol-generatingarticle10 during insertion of theheating element120 of the aerosol-generatingdevice110 into the aerosol-generatingsubstrate20.
• Once theinternal heating element120 is inserted into the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10 and theheating element120 is actuated, the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10 is heated to a temperature of approximately 350 degrees Celsius by theheating element120 of the aerosol-generatingdevice110. At this temperature, volatile compounds are evolved from the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10. As a user draws on the mouth end70 of the aerosol-generatingarticle10, the volatile compounds evolved from the aerosol-generatingsubstrate20 are drawn downstream through the aerosol-generatingarticle10 and condense to form an aerosol that is drawn through themouthpiece50 of the aerosol-generatingarticle10 into the user's mouth.
• As the aerosol passes downstream thorough the aerosol-coolingelement40, the temperature of the aerosol is reduced due to transfer of thermal energy from the aerosol to the aerosol-coolingelement40. When the aerosol enters the aerosol-coolingelement40, its temperature is approximately 60 degrees Celsius. Due to cooling within the aerosol-coolingelement40, the temperature of the aerosol as it exits the aerosol-cooling element is approximately 40 degrees Celsius.
• InFIG. 3, the components of the aerosol-generatingdevice110 are shown in a simplified manner. Particularly, the components of the aerosol-generatingdevice110 are not drawn to scale inFIG. 3. Components that are not relevant for the understanding of the embodiment have been omitted to simplifyFIG. 3.
• As shown inFIG. 3, the aerosol-generatingdevice110 comprises ahousing130. Theheating element120 is mounted within an aerosol-generating article receiving chamber within thehousing130. The aerosol-generating article10 (shown by dashed lines inFIG. 3) is inserted into the aerosol-generating article receiving chamber within thehousing130 of the aerosol-generatingdevice110 such that theheating element120 is directly inserted into the aerosol-generatingsubstrate20 of the aerosol-generatingarticle10.
• Within thehousing130 there is anelectrical energy supply140, for example a rechargeable lithium ion battery. Acontroller150 is connected to theheating element120, theelectrical energy supply140, and auser interface160, for example a button or display. Thecontroller150 controls the power supplied to theheating element120 in order to regulate its temperature.
EXAMPLE
• Homogenised tobacco sheets were formed based on each the compositions A-D shown below in Table 1, using a method as described above:

• TABLE 1
  	Sheet A	Sheet B	Sheet C	Sheet D
  Component	% by weight	% by weight	% by weight	% by weight

  Tobacco	75	75	75	75
  Glycerin	20	19	17.5	15
  MCT oil	0	1	2.5	5
  Guar	3	3	3	3
  Cellulose	2	2	2	2
  fibres

• The MCT oil used for Sheets B, C and D was Grindsted® MCT 60 X from Danisco. For each tobacco sheet, the tobacco sheet was formed into an aerosol-generating substrate, using conventional techniques. An aerosol-generating article as described above with reference toFIG. 1 was then assembled. The aerosol-generating articles incorporating Sheets B, C and D are according to the present invention, with medium chain triglyceride oil in the homogenised tobacco sheet. The aerosol-generating article incorporating Sheet A, which does not include the medium chain triglyceride oil, is a control sample for the purposes of comparison.
• Each aerosol-generating article was subjected to the heating test defined above, at both 350 degrees Celsius and 300 degrees Celsius. The nicotine level in the aerosol delivered from each aerosol-generating article were measured, with the results shown below in Table 2.
• As can be seen from Table 2, an increase in the delivery of nicotine from the aerosol-generating substrate was observed for the majority of the aerosol-generating articles incorporating medium chain triglyceride in the homogenised tobacco material, relative to the control sample. In the case of the aerosol-generating article incorporating Sheet D, with 5 percent by weight of medium chain triglyceride oil, an increase in the nicotine delivery of over 10 percent was observed relative to the control sample. When the temperature was reduced to 300 degrees Celsius, this increase in nicotine relative to the control sample went up to 25 percent.

• TABLE 2
  Level of MCT oil in	Nicotine		Nicotine
  aerosol-generating	delivery at	%	delivery at	%
  substrate (%)	350° C. (mg)	increase	300° C. (mg)	increase

  0	1.27	0	0.80	0
  1.0	1.27	0	0.82	2.5
  2.5	1.29	1.6	0.87	8.7
  5.0	1.42	12.0	1.00	25.0

• The homogenised tobacco sheets formed according to the example above, or any other homogenised tobacco material can be analysed in order to determine the content of medium chain triglycerides using the example test method described below.
Example Test Method for Determining Medium Chain Triglyceride Content
• In a first step, the homogenised tobacco material is ground to reduce the size, using cryogenic grinding with liquid nitrogen.
• In a second step, the homogenised tobacco material is extracted in methanol. In this step, 100 mg of the ground tobacco material is diluted with 5 millilitres LC-MS grade methanol containing the internal standards isophorone-d8 (10.62 micrograms per millimetre) and decanoic-d19 acid (20.52 micrograms per millimetre), both available from CDN Isotopes Inc. This is followed by vortexing of the liquid extract for 5 minutes and centrifugation of the liquid extract for 5 minutes at 10 degrees Celsius to separate the solid particles from the liquid extract. 200 microlitres of the remaining liquid extract is diluted with 800 microlitres of methanol and mixed for 5 minutes at 5 degrees Celsius and 2000 rpm, for example in ThermoMixer™.
• In a third step, the resultant sample is subjected to a chromatographic analysis using a reversed phase separation. A suitable apparatus for conducting a chromatographic analysis is a Hypersil™ GOLD column (150×2.1 millimetres, 1.9 micrometres; available from ThermoScientific, Waltham, Mass., USA) equipped with a UHPLC guard filter cartridge (10×2.1 millimetres, 0.2 micrometres; available from ThermoScientific, Waltham, Mass., USA) operating at 50 degrees Celsius with 1.5 microlitre injection volume with maintained autosampler temperature of 5 degrees Celsius.
• In a fourth step, the separated components from the chromatographic column are transferred to a mass spectrometer, for example, a Thermo QExactive™ mass spectrometer operated in both full scan and data dependent MS²modes using heated electrospray ionization (HESI) in positive and negative mode.
• In a final step, the data from the mass spectrometric detection is analysed to identify the compounds present. Compound identification is performed using a semi-automatic stepwise approach comparing the detected constituents with reference compounds in an experimental MS²fragmentation database and in-silico predicted fragmentation of chemicals from public databases. All putative hits are scored using Progenesis QI™ algorithms. Semi-quantification of the compounds can be carried out using peak volume abundance.

Claims (15)

1.-14. (canceled)

15. A heated aerosol-generating article for producing an inhalable aerosol, the heated aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate is formed of one or more sheets of a homogenised tobacco material, the homogenised tobacco material being formed of an agglomeration of particles of tobacco material and comprising between 1 percent by weight and 10 percent by weight of a medium chain triglyceride oil, on a dry weight basis, the medium chain triglyceride oil having a melting point below 18 degrees Celsius and comprising one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms, and wherein the one or more sheets of homogenised tobacco material are selected from reconstituted tobacco sheet and cast leaf.

16. The heated aerosol-generating article according toclaim 15, wherein the medium chain triglyceride oil has an iodine value of less than 2.

17. The heated aerosol-generating article according toclaim 15, wherein the medium chain triglyceride oil has a melting point below 15 degrees Celsius.

18. The heated aerosol-generating article according toclaim 15, wherein the medium chain triglyceride oil has a melting point below 10 degrees Celsius.

19. The heated aerosol-generating article according toclaim 15, wherein the medium chain triglyceride oil comprises at least 80 percent triglycerides having at least two fatty acid chains with a chain length of between 8 and 10 carbon atoms.

20. The heated aerosol-generating article according toclaim 15, wherein a total content of the medium chain triglyceride oil in the homogenised tobacco material is between 1 percent and 5 percent by weight, on a dry weight basis.

21. The heated aerosol-generating article according toclaim 15, wherein the homogenised tobacco material comprises at least 70 percent by weight tobacco, on a dry weight basis.

22. The heated aerosol-generating article according toclaim 15, wherein the homogenised tobacco material further comprises one or more aerosol formers.

23. The heated aerosol-generating article according toclaim 22, wherein the total content of aerosol former in the homogenised tobacco material is between 5 percent and 20 percent by weight, on a dry weight basis.

24. The heated aerosol-generating article according toclaim 15, wherein the homogenised tobacco material further comprises at least 1 percent by weight reinforcement fibres, on a dry weight basis.

25. The heated aerosol-generating article according toclaim 15, wherein the aerosol-generating substrate is a rod formed from a gathered sheet of the homogenised tobacco material.

26. A rod of aerosol-generating substrate for a heated aerosol-generating article according toclaim 15, the aerosol-generating substrate comprising a homogenised tobacco material comprising between 1 percent by weight and 10 percent by weight of a medium chain triglyceride oil, on a dry weight basis, the medium chain triglyceride oil having a melting point below 18 degrees Celsius and comprising one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms.

27. An aerosol-generating system, comprising:

an aerosol-generating device comprising a heating element; and

an aerosol-generating article for the aerosol-generating device, the aerosol-generating article comprising a rod of aerosol-generating substrate, wherein the rod of aerosol-generating substrate is formed of one or more sheets of a homogenised tobacco material, the homogenised tobacco material being formed of an agglomeration of particles of tobacco material and comprising between 1 percent by weight and 10 percent by weight of a medium chain triglyceride oil, on a dry weight basis, the medium chain triglyceride oil having a melting point below 18 degrees Celsius and comprising one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms,

wherein the one or more sheets of homogenised tobacco material are selected from reconstituted tobacco sheet and cast leaf.

28. A method of making a homogenised tobacco material for an aerosol-generating article according toclaim 15, the method comprising the steps of:

forming an homogenised slurry comprising tobacco material, water, and a medium chain triglyceride oil having a melting point below 18 degrees Celsius and comprising one or more triglycerides having at least two fatty acid chains with a chain length of between 6 and 12 carbon atoms;

casting the homogenised slurry onto a moving belt; and

drying the cast slurry to form a sheet of homogenised tobacco material,

wherein the method is performed without any external heating of the slurry.

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