CONCENTRATION OF WET TOBACCO EXTRACTS

Abstract

A method of manufacturing a concentrated tobacco extract for an aerosol-generating article is provided, including: providing a natural tobacco material; heating the material to a temperature and for a time such that volatile species including nicotine are released from the material, the heating includes heating the material in a flow of inert gas or in a flow of a combination of an inert gas with water or steam or heating the material under vacuum; collecting the released volatile species and forming a liquid, naturally derived tobacco extract including the collected species, a polyhydric alcohol, and at least about 40 percent by weight of water; and heating the liquid extract to evaporate at least some of the water and obtain concentrated tobacco extract, by heating to a temperature and for a time such that a water content in the naturally derived tobacco extract is reduced by at least about 60 percent.

Claims

1.-23. (canceled)

24. A method of manufacturing a concentrated tobacco extract for an aerosol-generating article, the method comprising: providing a natural tobacco material; heating the natural tobacco material to a temperature and for a time such that volatile species are released from the natural tobacco material, the volatile species comprising nicotine, wherein the heating the natural tobacco material comprises heating the natural tobacco material in a flow of inert gas or in a flow of a combination of an inert gas with water or steam or heating the natural tobacco material under vacuum; collecting the released volatile species and forming a liquid, naturally derived tobacco extract comprising the collected volatile species, a polyhydric alcohol, and at least about 40 percent by weight of water; and heating the liquid, naturally derived tobacco extract to evaporate at least some of the water and obtain concentrated tobacco extract, wherein the naturally derived tobacco extract is heated to a temperature and for a time such that a water content in the naturally derived tobacco extract is reduced by at least about 60 percent.

25. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated to a temperature and for a time such that the water content in the naturally derived tobacco extract is reduced by at least about 70 percent.

26. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated to a temperature and for a time such that the water content in the naturally derived tobacco extract is reduced by less than or equal to about 95 percent.

27. The method according to claim 24, wherein the liquid, naturally derived tobacco extract formed in the step of collecting the released volatile species further comprises at least about 30 percent by weight of the polyhydric alcohol.

28. The method according to claim 24, wherein the liquid, naturally derived tobacco extract formed in the step of collecting the released volatile species further comprises less than or equal to about 60 percent by weight of the polyhydric alcohol.

29. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated at a pressure of less than or equal to about 200 mbar.

30. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated at a pressure of at least about 20 mbar.

31. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated under a flow of air of at least about 10 kg/h.

32. The method according to claim 31, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated under a flow of air of at least about 15 kg/h.

33. The method according to claim 31, wherein a relative humidity of the flow of air is less than or equal to about 50 percent.

34. The method according to claim 31, wherein a relative humidity of the flow of air is less than or equal to about 25 percent.

35. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated to at least about 35 degrees Celsius.

36. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated to at least about 50 degrees Celsius.

37. The method according to claim 24, wherein in the step of heating the naturally derived tobacco extract, the naturally derived tobacco extract is heated to at least about 70 degrees Celsius.

38. The method according to claim 24, wherein the concentrated tobacco extract comprises less than or equal to about 20 percent by weight of water.

39. The method according to claim 24, wherein the concentrated tobacco extract comprises at least about 75 percent by weight of the polyhydric alcohol.

40. The method according to claim 24, wherein the natural tobacco material comprises one or more of Burley tobacco, Oriental tobacco, flue-cured tobacco.

41. The method according to claim 24, wherein the naturally derived tobacco extract comprises at least about 0.1 percent by weight nicotine.

42. The method according to claim 24, wherein the concentrated tobacco extract comprises less than about 70 micrograms/gram acetaldehyde.

43. The method according to claim 24, wherein the concentrated tobacco extract comprises less than about 14 micrograms/gram formaldehyde.

44. A concentrated, naturally derived tobacco extract, comprising: at least 0.2 percent by weight of nicotine; at least about 75 percent by weight of a polyhydric alcohol; less than about 20 percent by weight of water; and less than about 70 micrograms/gram acetaldehyde.

45. A concentrated, naturally derived tobacco extract, comprising: at least 0.2 percent by weight of nicotine; at least about 75 percent by weight of a polyhydric alcohol; less than about 20 percent by weight of water; and less than about 14 micrograms/gram formaldehyde.

46. An aerosol-generating system, comprising: a cartomizer comprising a reservoir holding a vaporisable nicotine formulation; a mouthpiece; and a heater configured to heat the vaporisable nicotine formulation, wherein the nicotine formulation comprises a concentrated, naturally derived tobacco extract comprising at least 0.2 percent by weight of nicotine, at least about 75 percent by weight of a polyhydric alcohol, less than about 20 percent by weight of water, and less than about 70 micrograms/gram acetaldehyde.

Description

EXAMPLE 1

[0129] A tobacco starting material is prepared from a flue-cured Bright tobacco material. The tobacco material is cut to form tobacco shreds having dimensions of 2.5 millimetres by 2.5 millimetres and the tobacco shreds are loaded into an extraction chamber, without compression. The tobacco starting material is heated within the extraction chamber to a temperature of 130 degrees Celsius for a period of 3 hours. During heating, a flow of nitrogen is passed through the extraction chamber at a flow rate of about 40 litres per minute.

[0130] The volatile compounds released from the tobacco starting material during the heating step are collected by absorption into a liquid solvent formed of polyethylene glycol at minus 10 degrees Celsius and with agitation of 750 rpm.

[0131] The solution of polyethylene glycol with the collected volatile compounds is concentrated to reduce the water content of the liquid tobacco extract to approximately 15 percent by weight. In more detail, the solution of polyethylene glycol with the collected volatile compounds is heated at 50 mbar to 75 degrees Celsius.

[0132] To this purpose, the solution of polyethylene glycol with the collected volatile compounds is circulated in a loop under vacuum. An evaporation tube defines a portion of the loop. The evaporation tube is arranged vertically and the solution of polyethylene glycol with the collected volatile compounds is made to flow from top to bottom by forming a thin film of the solution on the inner surface of the wall of the evaporation tube. The evaporation tube is heated externally to raise the temperature of the film. When the solution in the film reaches the boiling point, evaporation begins, and water is the main component of the solution leaving the film.

[0133] The evaporated water is condensed and removed from the loop. The solution of polyethylene glycol is circulated for as long as necessary to achieve the target water concentration. It will be clear to the skilled person that the time needed to achieve the target water concentration may typically depend on the size of the equipment and the amount of solution of polyethylene glycol to be processed. Further, the time needed to achieve the target water concentration may differ if the operation is run a continuous process or as a batch process.

[0134] The resultant concentrated liquid tobacco extract provides optimised levels of desirable flavour compounds such as β-damascenone and β-ionone whilst retaining relatively low levels of other undesirable tobacco compounds such as carbonyls, phenols, furans and TSNAs. In particular, the resultant concentrated liquid tobacco extract contains about 20 micrograms/g acetaldehyde and about 10 micrograms/g formaldehyde.

EXAMPLE 2

[0135] Three tobacco starting materials in accordance with the present invention are prepared from a flue-cured Bright tobacco material (2A), a Burley tobacco material (2B), and an Oriental tobacco material (2C), respectively.

[0136] Each one of the three tobacco materials is cut to form tobacco shreds having dimensions of 2.5 millimetres by 2.5 millimetres, and the tobacco shreds are loaded into an extraction chamber, without compression.

[0137] Each one of the tobacco starting materials is heated within the extraction chamber to a temperature of 130 degrees Celsius for a period of 120 minutes. During heating, a flow of nitrogen is passed through the extraction chamber at a flow rate of 2 litres per minute.

[0138] The volatile compounds released from each tobacco starting material during the heating step are collected by absorption into a liquid solvent formed of polypropylene glycol at 0 degrees Celsius.

[0139] A liquid tobacco extract is obtained directly from such extraction process. Each liquid extract obtained from each one of the three tobacco starting materials is then concentrated under vacuum (50 mbar) at 55 degrees Celsius until a moisture content of 12 percent±2 percent is reached.

TABLE-US-00001 TABLE 1 Value of selected ratios by weight of desirable to undesirable tobacco compounds within the liquid tobacco extracts (β-ionone + β- damascenone) to (4- (methylnitrosamino)-1-(3- pyridyl)-1-butanone + (furaneol + (R,S)-N-nitrosoanatabine + (2,3-diethyl- (R,S)-N- (β-ionone + 5-methylpyr- nitrosoanabasine + N- β-damascenone) azine)*100)) nitrosonornicotine + ((2- Example to (phenol) to (nicotine) furanemethanol)/600)) 2A 2.27 1.35 × 10.sup.−3 5.25 2B 2.96 1.71 × 10.sup.−3 3.50 2C 4.12 2.75 × 10.sup.−3 7.83

[0140] In all three liquid extracts in accordance with the invention 2A, 2B, and 2C the ratio by weight of (β-ionone+β-damascenone) to (phenol) is consistently and significantly above 2.0. Further, in all three liquid extracts in accordance with the invention 2A, 2B, and 2C the ratio by weight of (furaneol+(2,3-diethyl-5-methylpyrazine)*100)) to (nicotine) is consistently and significantly above 1×10.sup.−3. Additionally, in all three liquid extracts in accordance with the invention 2A, 2B, and 2C the ratio by weight of (β-ionone+β-damascenone) to (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone+(R,S)—N-nitrosoanatabine+(R,S)—N-nitrosoanabasine+N-nitrosonornicotine+((2-furanemethanol)/600)) is consistently and significantly above 3.