METHOD OF MAKING A TOBACCO EXTRACT

Abstract

Embodiments described herein provide a method of making a tobacco extract comprising; (a) contacting tobacco with an extraction solvent in a first chamber such that tobacco components are extracted from the tobacco into the extraction solvent, wherein the extraction solvent is a supercritical fluid in the first chamber; (b) passing the extraction solvent containing tobacco components along a line towards a second chamber, wherein a valve is present in the line and the conditions downstream of the valve are such that the extraction solvent is subcritical; and (c) pumping entrapment solvent into a flow downstream of the valve, wherein the tobacco components are released from the extraction solvent by transfer to subcritical conditions and are dissolved in the entrapment solvent, whereby the tobacco components dissolved in entrapment solvent are collected in the second chamber.

Claims

1. A method of making a tobacco extract, the method comprising: (a) contacting tobacco with an extraction solvent in a first chamber such that tobacco components are extracted from the tobacco into the extraction solvent, wherein the extraction solvent is a supercritical fluid in the first chamber; (a) passing the extraction solvent containing tobacco components along a line towards a second chamber, wherein a valve is present in the line and the conditions downstream of the valve are such that the extraction solvent is subcritical; and (c) pumping entrapment solvent into a flow downstream of the valve, wherein the tobacco components are released from the extraction solvent by transfer to subcritical conditions and are dissolved in the entrapment solvent, whereby the tobacco components dissolved in entrapment solvent are collected in the second chamber.

2. The method according to claim 1, wherein the extraction solvent comprises carbon dioxide.

3. The method according to claim 2 wherein at (a), the temperature is in the range of about 308-473K, preferably about 328-350K, and the pressure is in the range of about 8-85 MPa, preferably about 20-30 MPa.

4. The method according to claim 1, wherein the entrapment solvent comprises an aerosol generating agent.

5. The method according to claim 4, wherein the entrapment solvent comprises a polyol.

6. The method according to claim 5, wherein the entrapment solvent comprises glycerol and/or propylene glycol.

7. The method according to claim 1, wherein the tobacco components include one or more of nicotine and tobacco aromas and flavors.

8. The method according to claim 1, further comprising providing the entrapment solvent containing dissolved tobacco components in a cartridge, wherein the cartridge is configured for use in a smoking article.

9. A tobacco extract obtainable by a method according to claim 1.

10. A cartridge configured for use in a smoking article, the cartridge containing a tobacco extract according to claim 9.

11. A smoking article containing a tobacco extract according to claim 9.

12. Use of the tobacco extract obtainable by the method of claim 1 to generate an inhalable aerosol.

13. The use of claim 12, further comprising using the tobacco extract is used in a smoking article.

Description

DETAILED DESCRIPTION

[0027] 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.

[0028] In some cases, one or more flavors may be added to the tobacco extract. As used herein, the term “flavor” refers to materials which, where local regulations permit, may be used to create a desired taste or aroma in a product for adult consumers.

[0029] 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), flavor 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.

[0030] 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 vaporization and/or the condensation of a gas to an inhalable solid and/or liquid aerosol.

[0031] 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.

[0032] The weight ratio of aerosol generating agent to tobacco (dry weight) may be from about 2:1 to about 1:3, suitably from 3:2 to about 1:2, suitably about 1:1.

[0033] 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 2% to about 20% based on the dry weight of tobacco, suitably from about 2%, 5% or 8% to about 12%, 15%, 18% or 20%. This pre-treatment with water increases the transfer of polar tobacco components (such as flavors) from the tobacco to the entrapment solvent.

[0034] 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 8 MPa, 10 MPa, 15 MPa, 20 MPa or 25 MPa to about 85 MPa, 70 MPa, 55 MPa, 40 MPa or 30 MPa, suitably from 8-85 MPa, 15-40 MPa or 20-30 MPa. Where the supercritical fluid comprises carbon dioxide, the temperature at which extraction occurs may, in some cases, be from about 308K, 318K or 328K to about 473K, 430K, 390K or 350K, suitably from 308-473K, 308-430K, or 328-350K.

[0035] The transfer to subcritical conditions reduces the fluid density of the extraction solvent and consequently results in precipitation of the tobacco components. The conditions must be such that the pressure is below the critical pressure of the extraction solvent and/or the temperature is below the critical temperature of the extraction solvent. For thermal efficiency, the conditions are suitably such that the pressure is below the critical pressure of the extraction solvent while the temperature remains above the critical temperature.

[0036] The efficiency of separation of the tobacco components and the extraction solvent improves as the conditions move further below the critical point of the extraction solvent. However, the extraction solvent will typically be collected and stored after separation (requiring compression); in some cases, it may be recycled into an extraction chamber. Thus, the subcritical conditions are suitably not too far below the critical point to improve energy efficiency. The subcritical conditions are suitably selected to balance these conflicting requirements. Where the extraction solvent comprises carbon dioxide, the pressure at which separation occurs may, in some cases, be from about 3 MPa, 4 MPa, 5 MPa or 5.5 MPa to about 7.3 MPa, 7 MPa, 6.5 MPa, 6 MPa, 5.5 MPa or 5 MPa, suitably from 3-7.3 MPa, or 4-6 MPa. Where the extraction solvent comprises carbon dioxide, the temperature of the subcritical conditions under which separation occurs may, in some cases, be from about 280K, 300K, 320K or 330K to about 473K, 430K, 390K or 350K, suitably from 308-473K, 308-430K, or 328-350K.

[0037] The rate at which the entrapment solvent is pumped into the flow may be selected such that the flow of entrapment solvent into the system is approximately constant throughout the process.

EXAMPLES

[0038] Analytical Methods

[0039] Water activity values reported below were measured at 24.9-25.2° C. using the Aqualab Prewater Activity meter. The values were determined using the dewpoint method.

[0040] Viscosity values reported below were measured at 25° C. using a Gemini Rheometer from Bohlin Instruments.

[0041] Pre-Extraction (Pre-Treatment of Tobacco):

[0042] Ground Virginia tobacco leaf of the particle size ranging from 355 μm to 3.5 mm was pre-treated by addition of water (10% of total tobacco weight). The mixture of tobacco and water was left for equilibration for 15 minutes post water addition (which is sufficient time for the water to be fully absorbed).

[0043] The pre-treated tobacco (1.2 kg plus 10 wt % water) was placed in a stainless steel extraction basket and the basket placed in an extraction vessel (5 L autoclave). The basket was closed at its ends by sinter metal plates (pore diameter 100 μm, pressure drop across the plate is no more than 1 bar), which distributed the supercritical fluid at the entrance and prevented egress of solid particles at the exit. The use of the basket also allowed the fast charge and discharge of the extraction vessel. The basket was sealed against the extraction vessel wall in order to prevent flow of the supercritical fluid around it.

Example 1: Example of Process According to the Invention

[0044] The extraction vessel was linked to a separation vessel by a transfer line. A pressure regulation valve was present in the line. Carbon dioxide may suitably be pumped through the system at the rate 5-23 kg/hr. In this case, carbon dioxide was pumped through the system at the rate of 10 kg/hr.

[0045] The extraction chamber was maintained at 26 MPa and 338K and the separation chamber was maintained at 4.5 MPa and 318K. Precipitation of the extract in the separation chamber was achieved by pressure and temperature reduction (from supercritical to subcritical conditions) at the regulation valve, which reduced the fluiddensity of the carbon dioxide and therefore the solvent-power of the CO2. Glycerol, pre-heated to 318K was pumped into the line between the regulation valve and the separation vessel at 6.7 g/min (so that 1.2 kg of glycerol was injected into the line over the course of the experiment). The glycerol containing extracted tobacco components was collected at the bottom of the separator.

[0046] Gaseous CO2 exited the separator after passing through a liquid/gas divider (which removed any remaining liquid extract that is entrained in the gas). The CO2 was collected and recycled into the extraction chamber.

[0047] The process was run for three hours and then the CO2 flow was shut-off. The system was depressurized (to atmospheric conditions). The glycerol containing tobacco components was then drained from the separator vessel and weighed.

[0048] Comparative Test

[0049] A comparative test was run using the same apparatus as in example 1. However, the conditions were supercritical (26 MPa and 338K) throughout the apparatus. Further, rather than injecting glycerol into the line between the extraction and separation chambers, glycerol was simply provided in the separation chamber before the extraction was initiated and was present in the separation chamber throughout the process.

[0050] All other aspects of the comparative test were the same as in example 1.

[0051] The comparative test is a representative example of the processes described generally in EP1915064.

[0052] Data

[0053] Tobacco Extract Properties:

TABLE-US-00001 Water Nicotine Water NNN NNK Viscosity Density activity Experiment (mg/g) (wt %) (ng/g) (ng/g) (Pa s) pH (g/cm.sup.3) (Aw) Example 1 10.45 9.1 111 72 0.74 5.38 1.26 0.14 Comp. Test 4.7 5.5 1.1 9.1 0.32 6.73 1.25 0.24

[0054] It can be seen that injecting glycerol into the line between the extraction and separation chambers alters the chemical and physical nature of the extract.

[0055] Similar results have been observed when using Oriental or Burley starting tobaccos.

[0056] It can be seen that the viscosity of the extract of example 1 is more than twice that obtained by a process similar to that of EP1915064 (i.e. the comparative test). A more viscous extract is easier to handle and retain in a smoking article.

[0057] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and/or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilized and modifications may be made without departing from the scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.