Patent Description:
Tobacco material is heated in smoking articles for the purpose of releasing substances contained in the material and delivering these as an aerosol.

Smoking articles such as cigarettes, cigars and the like bum tobacco during use to create tobacco smoke. Attempts have been made to provide alternatives to these articles that bum tobacco by creating products that release compounds without burning. Examples of such products are heating devices which release compounds by heating, but not burning, material. The material may be, for example, tobacco or other non-tobacco products, which may or may not contain nicotine.

Electronic cigarettes or "e-cigarettes" are another product that has been formulated as an alternative to combustible products. These devices contain a volatilisble solution which generates an inhalable aerosol on heating. These solutions may contain components of tobacco. It is therefore useful to be able to selectively extract tobacco components.

<CIT> describes a process for making reconstituted tobacco including a tobacco extraction step. The extraction process uses supercritical carbon dioxide to extract tobacco components, and then contacts the supercritical carbon dioxide containing tobacco components with propylene glycol. The tobacco components transfer into the propylene glycol. The carbon dioxide is supercritical throughout. <CIT> relates to a process for the selective removal of basic materials from plant products, in particular, for removing nicotine from tobacco without materially affecting the content of the other components of the tobacco. <CIT> relates to E-cigarette or vaping devices or inhalation devices. <CIT> relates to a process for extracting nicotine in which tobacco is exposed to an extracting solvent in either liquid or gaseous state at temperatures below about <NUM> and at high pressures. <CIT> relates to a process for the extraction of volatile compounds with carbon dioxide and to the volatile compounds obtained by this process.

According to a first aspect of the present invention, there is provided a method of making a tobacco extract comprising;.

The inventors have established that variations in the extraction process using a supercritical extraction solvent result in variation in the tobacco extract composition and/or in the physical properties of the extract.

The extraction solvent is supercritical throughout steps (a) and (b). In some cases, the process may be isobaric and isothermal. The use of isobaric and isothermal conditions means that the solvent remains supercritical throughout and there is no need to reheat or re-pressurise the extraction solvent. The apparatus configuration is simpler than in <CIT>, because only one vessel is required. Further, the energy required to maintain the apparatus at supercritical conditions is reduced when using a single chamber as compared to a larger, multi-chamber arrangement (<CIT>).

At the end of the process, the method may additionally comprise the step of;
(c) altering the conditions in the vessel so that the extraction solvent is subcritical, thereby separating the extraction solvent and any remaining dissolved tobacco components, at least some of which are subsequently dissolved in the entrapment solvent.

The transfer to subcritical conditions enhances transfer of the dissolved tobacco components to the entrapment solvent, improving the organoleptic properties of the extract. In some cases, a further step of (d) washing the vessel with entrapment solvent which dissolves any tobacco components that are not already solvated. (The inventors have observed that some may condense on the vessel walls, for example.

The vessel may be configured in a number of ways. For example:.

In some cases, the supercritical extraction solvent may be circulated through the vessel and extracts components of tobacco on each pass. In some cases, an external line may be provided so that the supercritical extraction solvent can be flowed through the vessel from an inlet to an outlet, and then circulated back to the inlet via the external line. In some vessel configurations, the inlet may be at the base of the vessel and the outlet may be at the top. In some vessel configurations, the inlet may be at the top of the vessel and the outlet may be at the bottom. In some configurations, where the tobacco is disposed adjacent to the outlet and the entrapment solvent is disposed adjacent to the inlet, the dissolved tobacco components pass through the external line. Where an external line is present, it is maintained at the same supercritical conditions as in the vessel (i.e. the system is isobaric and isothermal).

In some cases, the entrapment solvent comprises an aerosol generating agent. In some cases, the entrapment solvent consists essentially or of consists of one or more aerosol generating agents.

In some cases, the extraction solvent used in the above process comprises carbon dioxide. In some cases, the extraction solvent consists essentially of or consists of carbon dioxide.

In some cases, the entrapment solvent used in the above method comprises a polyol. In some cases, the entrapment solvent comprises glycerol and/or propylene glycol. In some cases, the entrapment solvent consists essentially of or consists of glycerol.

In some cases, the tobacco components extracted by the methods described herein include one or more of nicotine and tobacco aromas and flavours.

According to a second aspect (which is not claimed), there is provided a tobacco extract obtained by or obtainable by a method described herein.

According to a further aspect (which is not claimed), there is provided a cartridge configured for use in a smoking article, the cartridge containing a tobacco extract obtained by or obtainable by a method described herein. The cartridge may be configured for use in an electronic cigarette.

According to a further aspect (which is not claimed), there is provided a smoking article containing a tobacco extract obtained by or obtainable by a method described herein. In some cases, the smoking article may contain the tobacco extract in an insertable cartridge, the cartridge being configured for use in the smoking article. The smoking article may additionally comprise a mouthpiece. The smoking article may additionally comprise a heater which volatilises the entrapment solvent containing tobacco extract in use.

The smoking article may be an electronic cigarette.

According to a further aspect (which is not claimed), there is provided the use of a tobacco extract obtained by or obtainable by a method described herein to generate an inhalable aerosol. In some cases, the tobacco extract is used in a smoking article to generate the inhalable aerosol.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only.

For the avoidance of doubt, the term "tobacco extract" as used herein refers to the entrapment solvent containing tobacco components.

A supercritical fluid is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. Supercritical fluids can effuse through solids like a gas, and dissolve materials like a liquid. Supercritical fluids have a higher fluid density than gases and therefore have a higher solvent capacity.

In some cases, one or more flavours may be added to the tobacco extract. As used herein, the term "flavour" refers to materials which, where local regulations permit, may be used to create a desired taste or aroma in a product for adult consumers. They may include extracts (e.g., licorice, hydrangea, Japanese white bark magnolia leaf, chamomile, fenugreek, clove, menthol, Japanese mint, aniseed, cinnamon, herb, wintergreen, cherry, berry, peach, apple, Drambuie, bourbon, scotch, whiskey, spearmint, peppermint, lavender, cardamom, celery, cascarilla, nutmeg, sandalwood, bergamot, geranium, honey essence, rose oil, vanilla, lemon oil, orange oil, cassia, caraway, cognac, jasmine, ylang-ylang, sage, fennel, piment, ginger, anise, coriander, coffee, or a mint oil from any species of the genus Mentha), flavour enhancers, bitterness receptor site blockers, sensorial receptor site activators or stimulators, sugars and/or sugar substitutes (e.g., sucralose, acesulfame potassium, aspartame, saccharine, cyclamates, lactose, sucrose, glucose, fructose, sorbitol, or mannitol), and other additives such as charcoal, chlorophyll, minerals, botanicals, or breath freshening agents. They may be imitation, synthetic or natural ingredients or blends thereof. They may be in any suitable form, for example, oil, liquid, or powder.

As used herein, an "aerosol generating agent" is an agent that promotes the generation of an aerosol on heating. An aerosol generating agent may promote the generation of an aerosol by promoting an initial vaporisation and/or the condensation of a gas to an inhalable solid and/or liquid aerosol.

In general, suitable aerosol generating agents include, but are not limited to: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as monohydric alcohols, high boiling point hydrocarbons, acids such as lactic acid, glycerol derivatives, esters such as diacetin, triacetin, triethylene glycol diacetate, triethyl citrate or myristates including ethyl myristate and isopropyl myristate and aliphatic carboxylic acid esters such as methyl stearate, dimethyl dodecanedioate and dimethyl tetradecanedioate. In some cases, the aerosol generating agent comprises one or more of glycerol, propylene glycol, triacetin and isopropyl myristate, suitably glycerol and/or propylene glycol.

The weight ratio of aerosol generating agent to tobacco (dry weight) may be from about <NUM>:<NUM> to about <NUM>:<NUM>, suitably from <NUM>:<NUM> to about <NUM>:<NUM>, suitably about <NUM>:<NUM>.

The method according to the invention may additionally comprise an initial step of adding water to the tobacco. The amount of water added may be from about <NUM>% to about <NUM>% based on the dry weight of tobacco, suitably from about <NUM>%, <NUM>% or <NUM>% to about <NUM>%, <NUM>%, <NUM>% or <NUM>%. This pre-treatment with water increases the transfer of polar tobacco components (such as flavours) from the tobacco to the entrapment solvent.

In the process according to the invention, a higher pressure under supercritical conditions increases the solvent capacity and increases the efficiency of extraction. However, more energy is required to achieve and maintain higher pressures. Thus, the supercritical conditions are suitably selected to balance these conflicting requirements.

Where the supercritical fluid comprises carbon dioxide, the pressure at which extraction occurs may, in some cases, be from about <NUM> MPa, <NUM> MPa, <NUM> MPa, <NUM> MPa or <NUM> MPa to about <NUM> MPa, <NUM> MPa, <NUM> MPa, <NUM> MPa or <NUM> MPa, suitably from <NUM>-<NUM> MPa, <NUM>- <NUM> MPa or <NUM>-<NUM> MPa. Where the supercritical fluid comprises carbon dioxide, the temperature at which extraction occurs may, in some cases, be from about <NUM> [<NUM>], <NUM> [<NUM>] or <NUM> [<NUM>] to about <NUM> [<NUM>], <NUM> [<NUM>], <NUM> [<NUM>] or <NUM> [<NUM>], suitably from <NUM> - <NUM> [<NUM>-<NUM>], <NUM> - <NUM> [<NUM>-<NUM>], or <NUM> - <NUM> [<NUM>-<NUM>].

Water activity values reported below were measured at <NUM> - <NUM> using the Aqualab Prewater Activity meter. The values were determined using the dewpoint method.

Viscosity values reported below were measured at <NUM> using a Gemini Rheometer from Bohlin Instruments.

Ground Virginia tobacco leaf of the particle size ranging from <NUM> to <NUM> was pre-treated by addition of water (<NUM>% of total tobacco weight). The mixture of tobacco and water was left for equilibration for <NUM> minutes post water addition (which is sufficient time for the water to be fully absorbed).

A stainless steel extraction vessel (<NUM> autoclave) with a solvent inlet at the base and outlet at the top, and an external circulation line connecting the outlet with the inlet, was loaded with pre-treated tobacco (<NUM> plus 10wt% water); the tobacco was placed on a stainless steel sintered plate in the bottom of the extraction vessel. The sintered plate distributes the supercritical fluid which enters the extraction vessel via a narrow inlet below the tobacco.

Filter paper was placed on top of the tobacco to hold tobacco particles in place and prevent them moving around the circulation loop / piping.

A liquid trap containing <NUM> of glycerol was placed on the top of the tobacco.

Carbon dioxide may suitably be pumped through the system at the rate <NUM>-<NUM>/hr.

In this instance, carbon dioxide was pumped through the system at the rate <NUM>/hr while the extraction chamber and circulation line were maintained at <NUM> MPa and <NUM> [<NUM>].

At these conditions, carbon dioxide is supercritical.

The supercritical CO<NUM> fluid flowed through the bed of ground tobacco and dissolved components of tobacco. The flow of supercritical CO<NUM> containing tobacco constituents then passed through the glycerol, tobacco components transferred into the glycerol.

CO<NUM> was circulated for <NUM> minutes and the system was then depressurised.

Separation of the extract from the supercritical CO<NUM> occurred during the depressurisation stage. Removal of CO<NUM> was achieved by pressure and temperature reduction with absorption of the extracted compounds in glycerol.

A comparative test was run using the same conditions as example <NUM>. However, the apparatus was different. <NUM> of glycerol was provided in a separation chamber, which is distinct from the extraction chamber. The separation and extraction chambers were linked by a transfer line. The supercritical solvent was circulated through the two chambers.

All other aspects of the comparative test were the same as in example <NUM>.

The comparative test is a representative example of the processes described generally in <CIT>.

Surprisingly, it can be seen that using a single chamber configuration (example <NUM>) rather than a multi-chamber arrangement (comparative test) alters the composition of the extract.

Claim 1:
A method of making a tobacco extract comprising;
(a) providing tobacco and an entrapment solvent in a partitioned vessel, wherein the tobacco and entrapment solvent are separated by a partition, and the vessel is configured such that the tobacco and entrapment solvent cannot contact each other;
(b) flowing a supercritical extraction solvent through the vessel, wherein the extraction solvent and any dissolved substances can pass through the partition; whereby tobacco components are extracted from the tobacco into the extraction solvent and carried across the partition, wherein the extraction solvent contacts the entrapment solvent and tobacco components are transferred from the extraction solvent into the entrapment solvent; and
(c) providing the entrapment solvent containing dissolved tobacco components in a cartridge, wherein the cartridge is configured for use in a smoking article.