NOVEL AEROSOL-GENERATING SUBSTRATE COMPRISING THYMUS SPECIES

Abstract

A heatable aerosol-generating article is provided, including: an aerosol-generating substrate including a homogenised thyme material including at least 2.5 percent by weight of thyme particles on a dry weight basis, an aerosol former, and a binder, at least 400 micrograms of ursolic acid per gram of the aerosol-generating substrate, on a dry weight basis, and at least 150 micrograms of thymol per gram of the aerosol-generating substrate, on a dry weight basis, in which an amount of ursolic acid per gram of the aerosol-generating substrate is at least 2 times an amount of thymol per gram of the aerosol-generating substrate; and at least one hollow tube immediately downstream of the aerosol-generating substrate. An aerosol-generating system, including an aerosol-generating device including a heating element, and the heated aerosol-generating article, is also provided.

Claims

1-16. (canceled)

17. A heatable aerosol-generating article, comprising: an aerosol-generating substrate comprising a homogenised thyme material comprising at least 2.5 percent by weight of thyme particles on a dry weight basis, an aerosol former, and a binder, at least 400 micrograms of ursolic acid per gram of the aerosol-generating substrate, on a dry weight basis, and at least 150 micrograms of thymol per gram of the aerosol-generating substrate, on a dry weight basis, wherein an amount of ursolic acid per gram of the aerosol-generating substrate is at least 2 times an amount of thymol per gram of the aerosol-generating substrate; and at least one hollow tube immediately downstream of the aerosol-generating substrate.

18. The heatable aerosol-generating article according to claim 17, wherein the aerosol-generating substrate further comprises between 1 milligram and 20 milligrams of nicotine per gram of the aerosol-generating substrate, on a dry weight basis.

19. The heatable aerosol-generating article according to claim 17, wherein the homogenised thyme material comprises between 5 percent by weight and 55 percent by weight of the aerosol former and between 1 percent by weight and 10 percent by weight of the binder, on a dry weight basis.

20. The heatable aerosol-generating article according to claim 17, wherein the binder comprises guar gum.

21. The heatable aerosol-generating article according to claim 17, wherein the binder comprises cellulose ether.

22. The heatable aerosol-generating article according to claim 21, wherein the aerosol-generating substrate further comprises additional cellulose that is not derived from the thyme particles, and wherein the additional cellulose comprises at least one of cellulose powder and cellulose fibres.

23. The heatable aerosol-generating article according to claim 17, wherein the homogenised thyme material further comprises tobacco particles, and wherein a weight ratio of the thyme particles to the tobacco particles is no more than 1:3.

24. The heatable aerosol-generating article according to claim 17, wherein the homogenised thyme material in the aerosol-generating substrate is in a form of cast leaf.

25. The heatable aerosol-generating article according to claim 17, wherein the homogenised thyme material in the aerosol-generating substrate is in a form of thyme paper.

26. The heatable aerosol-generating article according to claim 17, wherein upon heating of the aerosol-generating substrate according to Test Method A, aerosol generated from the aerosol-generating substrate comprises: at least 10 micrograms of ursolic acid per gram of the aerosol-generating substrate, on a dry weight basis, and at least 5 micrograms of thymol per gram of the aerosol-generating substrate, on a dry weight basis, wherein an amount of ursolic acid in the aerosol per gram of the aerosol-generating substrate is at least equal to an amount of thymol in the aerosol per gram of the aerosol-generating substrate.

27. The heatable aerosol-generating article according to claim 17, wherein upon heating of the aerosol-generating substrate according to Test Method A, aerosol generated from the aerosol-generating substrate comprises: ursolic acid in an amount of at least 0.25 micrograms per puff of the aerosol, and thymol in an amount of at least 0.1 micrograms per puff of the aerosol, wherein a puff of the aerosol has a volume of 55 millilitres as generated by a smoking machine, and wherein the amount of ursolic acid per puff of the aerosol is at least equal to the amount of thymol per puff of the aerosol.

28. An aerosol-generating system, comprising: an aerosol-generating device comprising a heating element; and a heatable aerosol-generating article according to claim 17.

Description

[0410] Specific embodiments will be further described, by way of example only, with reference to the accompanying drawings in which:

[0411] FIG. 1 illustrates a first embodiment of a substrate of an aerosol-generating article as described herein;

[0412] FIG. 2 illustrates an aerosol-generating system comprising an aerosol-generating article and an aerosol-generating device comprising an electric heating element;

[0413] FIG. 3 illustrates an aerosol-generating system comprising an aerosol-generating article and an aerosol-generating device comprising a combustible heating element;

[0414] FIGS. 4a and 4b illustrate a second embodiment of a substrate of an aerosol-generating article as described herein; [0415] FIG. 5 illustrates a third embodiment of a substrate of an aerosol-generating article as described herein;

[0416] FIGS. 6a, 6b and 6c each show a cross sectional view of filter 1050 further comprising an aerosol-modifying element, wherein [0417] FIG. 6a illustrates the aerosol-modifying element in the form of a spherical capsule or bead within a filter plug. [0418] FIG. 6b illustrates the aerosol-modifying element in the form of a thread within a filter plug. [0419] FIG. 6c illustrates the aerosol-modifying element in the form of a spherical capsule within a cavity within the filter;

[0420] FIG. 7 is a cross sectional view of a plug of aerosol-generating substrate 1020 further comprising an elongate susceptor element; and

[0421] FIG. 8 illustrates an experimental set-up for collecting aerosol samples to be analysed in order to measure characteristic compounds.

[0422] FIG. 1 illustrates a heated aerosol-generating article 1000 comprising a substrate as described herein. The article 1000 comprises four elements; the aerosol-generating substrate 1020, a hollow cellulose acetate tube 1030, a spacer element 1040, and a mouthpiece filter 1050. These four elements are arranged sequentially and in coaxial alignment and are assembled by a cigarette paper 1060 to form the aerosol-generating article 1000. The article 1000 has a mouth-end 1012, which a user inserts into his or her mouth during use, and a distal end 1013 located at the opposite end of the article to the mouth end 1012. The embodiment of an aerosol-generating article illustrated in FIG. 1 is particularly suitable for use with an electrically-operated aerosol-generating device comprising a heater for heating the aerosol-generating substrate.

[0423] When assembled, the article 1000 is about 45 millimetres in length and has an outer diameter of about 7.2 millimetres and an inner diameter of about 6.9 millimetres.

[0424] The aerosol-generating substrate 1020 comprises a plug formed from a sheet of homogenised thyme material comprising thyme particles, either alone or in combination with tobacco particles.

[0425] A number of examples of a suitable homogenised thyme material for forming the aerosol-generating substrate 1020 are shown in Table 1 below (see Samples A to D). The sheet is gathered, crimped and wrapped in a filter paper (not shown) to form the plug. The sheet includes additives, including glycerol as an aerosol former.

[0426] An aerosol-generating article 1000 as illustrated in FIG. 1 is designed to engage with an aerosol-generating device in order to be consumed. Such an aerosol-generating device includes means for heating the aerosol-generating substrate 1020 to a sufficient temperature to form an aerosol. Typically, the aerosol-generating device may comprise a heating element that surrounds the aerosol-generating article 1000 adjacent to the aerosol-generating substrate 1020, or a heating element that is inserted into the aerosol-generating substrate 1020.

[0427] Once engaged with an aerosol-generating device, a user draws on the mouth-end 1012 of the smoking article 1000 and the aerosol-generating substrate 1020 is heated to a temperature of about 375 degrees Celsius. At this temperature, volatile compounds are evolved from the aerosol-generating substrate 1020. These compounds condense to form an aerosol. The aerosol is drawn through the filter 1050 and into the user's mouth.

[0428] FIG. 2 illustrates a portion of an electrically-operated aerosol-generating system 2000 that utilises a heating blade 2100 to heat an aerosol-generating substrate 1020 of an aerosol-generating article 1000. The heating blade is mounted within an aerosol article receiving chamber of an electrically-operated aerosol-generating device 2010. The aerosol-generating device defines a plurality of air holes 2050 for allowing air to flow to the aerosol-generating article 1000. Air flow is indicated by arrows on FIG. 2. The aerosol-generating device comprises a power supply and electronics, which are not illustrated in FIG. 2. The aerosol-generating article 1000 of FIG. 2 is as described in relation to FIG. 1.

[0429] In an alternative configuration shown in FIG. 3, the aerosol-generating system is shown with a combustible heating element. While the article 1000 of FIG. 1 is intended to be consumed in conjunction with an aerosol-generating device, the article 1001 of FIG. 3 comprises a combustible heat source 1080 that may be ignited and transfer heat to the aerosol-generating substrate 1020 to form an inhalable aerosol. The combustible heat source 80 is a charcoal element that is assembled in proximity to the aerosol-generating substrate at a distal end 13 of the rod 11. Elements that are essentially the same as elements in FIG. 1 have been given the same numbering.

[0430] FIGS. 4a and 4b illustrate a second embodiment of a heated aerosol-generating article 4000a, 4000b. The aerosol-generating substrate 4020a, 4020b comprises a first downstream plug 4021 formed from of particulate plant material comprising thyme particles, and a second upstream plug 4022 formed from particulate plant material comprising primarily tobacco particles. A suitable homogenised thyme material for use in the first downstream plug is shown in Table 1 below as one of Samples A to D. A suitable homogenised tobacco material for use in the second upstream plug is shown in Table 1 below as Sample E. Sample E comprises only tobacco particles and is included for the purposes of comparison only.

[0431] In each of the plugs, the homogenised plant material is in the form of sheets, which are crimped and wrapped in a filter paper (not shown). The sheets both include additives, including glycerol as an aerosol former. In the embodiment shown in FIG. 4a, the plugs are combined in an abutting end to end relationship to form the rod and are of equal length of about 6 mm each. In a more preferred embodiment (not shown), the second plug is preferably longer than the first plug, for example, preferably 2 mm longer, more preferably 3 mm longer, such that the second plug is 7 or 7.5 mm in length while the first plug is 5 or 4.5 mm in length, to provide a desired ratio of tobacco to thyme particles in the substrate. In FIG. 4b, the cellulose acetate tube support element 1030 has been omitted.

[0432] The article 4000a, 4000b, analogously to the article 1000 in FIG. 1, is particularly suitable for use with the electrically-operated aerosol-generating system 2000 comprising a heater shown in FIG. 2. Elements that are essentially the same elements in FIG. 1 have been given the same numbering. It may be envisaged by the skilled person that a combustible heat source (not shown) may be instead be used with the second embodiment in lieu of the electrical heating element, in a configuration similar to the configuration containing combustible heat source 1080 in article 1001 of FIG. 3.

[0433] FIG. 5 illustrates a third embodiment of a heated aerosol-generating article 5000. The aerosol-generating substrate 5020 comprises a rod formed from a first sheet of homogenised thyme material formed of particulate plant material comprising a proportion of thyme particles, and a second sheet of homogenised tobacco material comprising primarily cast-leaf tobacco.

[0434] A suitable homogenised thyme material for use as the first sheet is shown in Table 1 below as one of Samples A to D. A suitable homogenised tobacco material for use as the second sheet is shown in Table 1 below as Sample E. Sample E comprises only tobacco particles and is included for the purposes of comparison only.

[0435] The second sheet overlies the first sheet, and the combined sheets have been crimped, gathered and at least partially wrapped in a filter paper (not shown) to form a plug that is part of the rod. Both sheets include additives, including glycerol as an aerosol former. The article 5000, analogously to the article 1000 in FIG. 1, is particularly suitable for use with the electrically-operated aerosol-generating system 2000 comprising a heater shown in FIG. 2. Elements that are essentially the same elements in FIG. 1 have been given the same numbering. It may be envisaged by the skilled person that a combustible heat source (not shown) may be instead be used with the third embodiment in lieu of the electrical heating element, in a configuration similar to the configuration containing combustible heat source 1080 in article 1001 of FIG. 3.

[0436] FIGS. 6a, 6b and 6c are cross sectional views of filter 1050 further comprising an aerosol-modifying element. In FIG. 6a, the filter 1050 further comprises an aerosol-modifying element in the form of a spherical capsule or bead 605.

[0437] In the embodiment of FIG. 6a, the capsule or bead 605 is embedded in the filter segment 601 and is surrounded on all sides by the filter material 603. In this embodiment, the capsule comprises an outer shell and an inner core, and the inner core contains a liquid flavourant. The liquid flavourant is for flavouring aerosol during use of the aerosol-generating article provided with the filter. The capsule 605 releases at least a portion of the liquid flavourant when the filter is subjected to external force, for example by squeezing by a consumer. In the embodiment shown, the capsule is generally spherical, with a substantially continuous outer shell containing the liquid flavourant.

[0438] In the embodiment of FIG. 6b, the filter segment 601 comprises a plug of filter material 603 and a central flavour-bearing thread 607 that extends axially through the plug of filter material 603 parallel to the longitudinal axis of the filter 1050. The central flavour-bearing thread 607 is of substantially the same length as the plug of filter material 603, so that the ends of the central flavour-bearing thread 607 are visible at the ends of the filter segment 601. In FIG. 6b, filter material 603 is cellulose acetate tow. The central flavour-bearing thread 607 is formed from twisted filter plug wrap and loaded with an aerosol-modifying agent.

[0439] In the embodiment of FIG. 6c, the filter segment 601 comprises more than one plug of filter material 603, 603′. Preferably, the plugs of filter material 603, 603′ are formed from cellulose acetate, such that they are able to filter the aerosol provided by the aerosol generating article. A wrapper 609 is wrapped around and connects filter plugs 603, 603′. Inside a cavity 611 is a capsule 605 comprising an outer shell and an inner core, and the inner core contains a liquid flavourant. The capsule is otherwise similar to the embodiment of FIG. 6a.

[0440] FIG. 7 is a cross sectional view of aerosol-generating substrate 1020 further comprising an elongate susceptor strip 705. The aerosol-generating substrate 1020 comprises a plug 703 formed from a sheet of homogenised thyme material comprising tobacco particles and thyme particles. The elongate susceptor strip 705 is embedded within the plug 703 and extends in a longitudinal direction between the upstream and downstream ends of the plug 703. During use, the elongate susceptor strip 705 heats the homogenised thyme material by means of induction heating, as described above.

EXAMPLE

[0441] Different samples of homogenised plant material for use in an aerosol-generating substrate according to the invention, as described above with reference to the figures, may be prepared from aqueous slurries having compositions shown Table 1. Sample A comprises only thyme particles and no tobacco particles, in accordance with the invention. Samples B to D comprise thyme particles and tobacco particles, in accordance with the invention. Sample E comprises only tobacco particles and is included for the purposes of comparison only.

[0442] Sample A is formed with a CMC binder in combination with cellulose fibres, in accordance with the second preferred embodiment of the invention. Sample A is prepared from an aqueous slurry containing 72.97 kg of water per 100 kg of slurry, with the remainder accounted for by the components in the relative amounts shown in Table 1.

[0443] Samples B to D are formed with an amount of thyme particles at or below 25 percent by weight, and a guar gum binder, in accordance with the first preferred embodiment of the invention. Samples B to D are prepared from an aqueous slurry containing between 78-79 kg of water per 100 kg of slurry.

[0444] In the table below, % DWB refers to the “dry weight base,” in this case, the percent by weight calculated relative to the dry weight of the homogenised plant material. The thyme powder may be formed from dried thymes, which may be ground to a final D95=77.3 microns by triple impact milling.

[0445] The slurries may be casted using a casting bar (0.6 mm) on a glass plate, dried in an oven at 140 degrees Celsius for 7 minutes, and then dried in a second oven at 120 degrees Celsius for 30 seconds.

TABLE-US-00001 TABLE 1 Dry content of slurries Thyme Tobacco Glyc- Guar CMC Cellulose Sam- (% (% erol (% Gum (% (% fibers (% ple DWB) DWB) DWB) DWB) DWB) DWB) A 75 0 16.7 0 4.6 3.7 B 23.3 54.3 16.6 2.1 0 3.7 C 7.5 67.5 18 3 0 4 D 2.5 72.5 18 3 0 4 E 0 75 18 3 0 4

[0446] For each of the samples A to E of homogenised plant material, a plug may be produced from a single continuous sheet of the homogenised plant material, the sheets each having widths of between 100 mm to 130 mm. The individual sheets preferably have a thickness of about 220 microns and a grammage of about 189 g/m.sup.2. The cut width of each sheet is about 120 mm. The sheets may be crimped to a height of 165 microns to 170 microns, and rolled into plugs having a length of about 12 mm and diameters of about 7 mm, circumscribed by a paper wrapper. The weight of homogenised plant material in each plug is about 272 mg and the total weight of each plug is about 281 mg.

[0447] For each of the plugs, an aerosol-generating article having an overall length of about 45 mm may be formed having a structure as shown in FIG. 3 comprising, from the downstream end: a mouth end cellulose acetate filter (about 7 mm long), an aerosol spacer comprising a crimped sheet of polylactic acid polymer (about 18 mm long), a hollow acetate tube (about 8 mm long) and the plug of aerosol-generating substrate.

[0448] For Sample A of homogenised plant material, for which thyme particles make up 100 percent of the particulate plant material, the characteristic compounds were extracted from the plug of homogenised plant material using methanol as detailed above. The extract was analysed as described above to confirm the presence of the characteristic compounds and to measure the amounts of the characteristic compounds. The results of this analysis are shown below in Table 2, wherein the amounts indicated correspond to the amount per aerosol-generating article, wherein the aerosol-generating substrate of the aerosol-generating article contained 272 mg of the Sample A of homogenised plant material.

[0449] For the purposes of comparison, the amounts of the characteristic compounds present in the particulate plant material (thyme particles) used to form Sample A are also shown. For the particulate material, the amounts indicated correspond to the amount of the characteristic compound in a sample of particulate plant material having a weight corresponding to the total weight of the particulate plant material in the aerosol-generating article containing 272 mg of Sample A.

TABLE-US-00002 TABLE 2 Amount of thyme-specific compounds in the particulate plant material and in the aerosol-generating substrate Amount in the particulate Amount in the aerosol- Characteristic plant material generating substrate Compound (micrograms per article) (micrograms per article) Ursolic acid 1589.6 1899.3 Thymol 340.0 741.2 Isothymol 76.1 327.3 Betulinic acid 5641.9 4917.2 Thymohydro- 14.1 177.1 quinone

[0450] For each of the other samples comprising a proportion of thyme particles, the amount of the characteristic compounds can be estimated based on the values in Table 2 by assuming that the amount is present in proportion to the weight of the thyme particles.

[0451] Mainstream aerosols of the aerosol-generating articles incorporating aerosol-generating substrates formed from Samples A to E of homogenised plant material may be generated in accordance with Test Method A, as defined above. For each sample, the aerosol that is produced may be trapped and analysed.

[0452] As described in detail above, according to Test Method A, the aerosol-generating articles may be tested using the commercially available IQOS® heat-not-burn device tobacco heating system 2.2 holder (THS2.2 holder) from Philip Morris Products SA. The aerosol-generating articles are heated under a Health Canada machine-smoking regimen over 30 puffs with a puff volume of 55 ml, puff duration of 2 seconds and a puff interval of 30 seconds (as described in ISO/TR 19478-1:2014).

[0453] The aerosol generated during the smoking test is collected on a Cambridge filter pad and extracted with a liquid solvent. FIG. 10 shows suitable apparatus for generating and collecting the aerosol from the aerosol-generating articles.

[0454] Aerosol-generating device 111 shown in FIG. 10 is a commercially available tobacco heating device (IQOS). The contents of the mainstream aerosol generated during the Health Canada smoking test as detailed above are collected in aerosol collection chamber 113 on aerosol collection line 120. Glass fiber filter pad 140 is a 44 mm Cambridge glass fiber filter pad (CFP) in accordance with ISO 4387 and ISO 3308.

For LC-HRAM-MS Analysis

[0455] Extraction solvent 170, 170a, which in this case is methanol and internal standard (ISTD) solution, is present at a volume of 10 mL in each micro-impinger 160, 160a. The cold baths 161, 161a each contain a dry ice-isopropyl ether to maintain the micro-impingers 160, 160a each at approximately −60° C. The gas-vapour phase is trapped in the extraction solvent 170, 170a as the aerosol bubbles through micro-impingers 160, 160a. The combined solutions from the two micro-impingers are isolated as impinger-trapped gas-vapor phase solution 180 in step 181.

[0456] The CFP and the impinger-trapped gas-vapor phase solution 180 are combined in a clean Pyrex® tube in step 190. In step 200, the total particulate matter is extracted from the CFP using the impinger-trapped gas-vapor phase solution 180 (which contains methanol as a solvent) by thoroughly shaking (disintegrating the CFP), vortexing for 5 min and finally centrifuging (4500 g, 5 min, 10° C.). Aliquots (300 μL) of the reconstituted whole aerosol extract 220 were transferred into a silanized chromatographic vial and diluted with methanol (700 μL), since the extraction solvent 170, 170a already comprised internal standard (ISTD) solution. The vials were closed and mixed for 5 minutes using an Eppendorf ThermoMixer (5° C.; 2000 rpm).

[0457] Aliquots (1.5 μL) of the diluted extracts were injected and analyzed by LC-HRAM-MS in both full scan mode and data-dependent fragmentation mode for compound identification.

For GCxGC-TOFMS Analysis

[0458] As discussed above, when samples for GCxGC-TOFMS experiments are prepared, different solvents are suitable for extracting and analysing polar compounds, non-polar compounds and volatile compounds separated from whole aerosol. The experimental set-up is identical to that described with respect to sample collection for LC-HRAM-MS, with the exceptions indicated below.

Nonpolar & Polar

[0459] Extraction solvent 171,171a, is present at a volume of 10 mL and is an 80:20 v/v mixture of dichlormethane and methanol, also containing retention-index marker (RIM) compounds and stable isotopically labeled internal standards (ISTD). The cold baths 162, 162a each contain a dry ice-isopropanol mixture to maintain the micro-impingers 160, 160a each at approximately −78° C. The gas-vapor phase is trapped in the extraction solvent 171, 171a as the aerosol bubbles through micro-impingers 160, 160a. The combined solutions from the two micro-impingers are isolated as impinger-trapped gas-vapor phase solution 210 in step 182.

Nonpolar

[0460] The CFP and the impinger-trapped gas-vapor phase solution 210 are combined in a clean Pyrex® tube in step 190. In step 200, the total particulate matter is extracted from the CFP using the impinger-trapped gas-vapor phase solution 210 (which contains dichloromethane and methanol as a solvent) by thoroughly shaking (disintegrating the CFP), vortexing for 5 min and finally centrifuging (4500 g, 5 min, 10° C.) to isolate the polar and non-polar components of the whole aerosol extract 230.

[0461] In step 250, an 10 mL aliquot 240 of the whole aerosol extract 230 was taken. In step 260, a 10 mL aliquot of water is added, and the entire sample is shaken and centrifuged. The non-polar fraction 270 was separated, dried with sodium sulfate and analysed by GCxGC-TOFMS in full scan mode.

Polar

[0462] ISTD and RIM compounds were added to polar fraction 280, which was then directly analysed by GCxGC-TOFMS in full scan mode.

[0463] Each smoking replicate (n=3) comprises the accumulated trapped and reconstituted non-polar fraction 270 and polar fraction 280 for each sample

Volatile Components

[0464] Whole aerosol was trapped using two micro-impingers 160, 160a in series. Extraction solvent 172, 172a, which in this case is N,N-dimethylformamide (DMF) containing retention-index marker (RIM) compounds and stable isotopically labeled internal standards (ISTD), is present at a volume of 10 mL in each micro-impinger 160, 160a. The cold baths 161, 161a each contain a dry ice-isopropyl ether to maintain the micro-impingers 160, 160a each at approximately −60° C. The gas-vapor phase is trapped in the extraction solvent 170, 170a as the aerosol bubbles through micro-impingers 160, 160a. The combined solutions from the two micro-impingers are isolated as a volatile-containing phase 211 in step 183. The volatile-containing phase 211 is analysed separately from the other phases and injected directly into the GCxGC-TOFMS using cool-on-column injection without further preparation.

[0465] Table 3 below shows the levels of the characteristic compounds from the thyme particles in the aerosol generated from an aerosol-generating article incorporating Sample A of homogenised plant material, including 75 percent by weight of thyme particles. For the purposes of comparison, Table 3 also shows the levels of the characteristic compounds in the aerosol generated from an aerosol-generating article incorporating Sample E of homogenised plant material, including tobacco particles only (and therefore not in accordance with the invention).

TABLE-US-00003 TABLE 3 Content of characteristic compounds in aerosol Sample A Sample A Sample A (micrograms Sample E (micrograms (micrograms per 55 ml (micrograms Compound per article) per gram) puff) per article) Ursolic acid 59.4 218.4 5.0 0.1 Thymol 33.6 123.5 2.8 0.3 Isothymol 2.9 10.7 0.24 0.0 Betulinic acid 195.6 719.0 16.3 0.3 Thymohydro- 2.8 10.3 0.23 0.0 quinone

[0466] In the aerosol generated from Sample A, relatively high levels of the characteristic compounds were measured. The ratio of ursolic acid to thymol was greater than 1.5. The levels of the characteristic compounds were therefore indicative of the presence of thyme particles in the sample. In contrast, for the tobacco only Sample E, which contained substantially no thyme particles, the levels of the characteristic compounds were found to be at or close to zero.

[0467] For each of the other samples B to D comprising a proportion of thyme particles, the amount of the characteristic compounds in the aerosol can be estimated based on the values in Table 3 by assuming that the amount is present in proportion to the weight of the thyme particles in the aerosol-generating substrate from which the aerosol is generated.

[0468] Table 4 below compares the levels of certain aerosol constituents in the aerosol generated from an aerosol-generating article incorporating sample B (30:70 ratio of thyme to tobacco) with the aerosol generated from the tobacco only Sample E. The reduction indicated is the percentage reduction provided by replacing 30 percent of the tobacco particles in the homogenised material of Sample E with thyme particles.

TABLE-US-00004 TABLE 4 Composition of aerosol Sample E Sample B Reduction Aerosol Constituent (100% tobacco) (30% thyme) (%) benzo[a]pyrene 1.00 0.61 39.3 (μg/article) benz[a]anthracene 1.95 1.21 37.8 (μg/article) dibenz[a,h]anthracene 0.13 0.06 53.0 (μg/article) phenol 1.53 0.80 47.5 (μg/article) o-cresol 0.081 0.041 49.4 (μg/article) m-cresol 0.036 0.021 42.0 (μg/article) p-cresol 0.073 0.051 30.1 (μg/article) m_p-cresol 0.11 0.07 34.0 (μg/article) isoprene 0.14 0.07 49.8 (μg/article) 1,3 butadiene 0.04 0.02 35.3 (μg/article)

[0469] As shown in Table 4, the aerosol produced from Sample B containing 30 percent by weight thyme particles based on the dry weight of the particulate plant material results in reduced levels of several undesirable aerosol compounds when compared to the aerosol produced from Sample E. For examples, a significant reduction was seen in the level of several polycyclic aromatic hydrocarbons (PAHs) including: benzo[a]pyrene, benz[a]anthracene and dibenz[a,h]anthracene pyrene. A significant reduction was also seen in the level of several phenolic compounds including: phenol, o-cresol, m-cresol, p-cresol and m_p-cresol, as well as isoprene and 1,3 butadiene.

[0470] In most cases, the reduction provided in the level of these undesirable aerosol compounds is significantly greater than the proportional reduction that would be expected as a result of the substitution of 30 percent of tobacco particles for thyme particles. The inclusion of the thyme particles in combination with the tobacco particles is therefore providing an unexpectedly high reduction in the levels of these compounds. The inclusion of thyme particles can therefore provide an aerosol that has improved sensory attributes whilst reducing the levels of certain undesirable compounds in the aerosol.