Concentration of wet tobacco extracts
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.
1 . A method of manufacturing a concentrated tobacco extract for an aerosol-generating article, the method comprising:
preparing a natural tobacco material, wherein in the step of preparing the natural tobacco material, the natural tobacco material is not subjected to any treatment adapted to alter the pH of the tobacco;
providing the 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.
2 . The method according to claim 1 , 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.
3 . The method according to claim 1 , 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.
4 . The method according to claim 1 , 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.
5 . The method according to claim 1 , 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.
6 . The method according to claim 1 , 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.
7 . The method according to claim 1 , 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.
8 . The method according to claim 1 , 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.
9 . The method according to claim 8 , 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.
10 . The method according to claim 8 , wherein a relative humidity of the flow of air is less than or equal to about 50 percent.
11 . The method according to claim 8 , wherein a relative humidity of the flow of air is less than or equal to about 25 percent.
12 . The method according to claim 1 , 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.
13 . The method according to claim 1 , 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.
14 . The method according to claim 1 , 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.
15 . The method according to claim 1 , wherein the concentrated tobacco extract comprises less than or equal to about 20 percent by weight of water.
16 . The method according to claim 1 , wherein the concentrated tobacco extract comprises at least about 75 percent by weight of the polyhydric alcohol.
17 . The method according to claim 1 , wherein the natural tobacco material comprises one or more of Burley tobacco, Oriental tobacco, flue-cured tobacco.
18 . The method according to claim 1 , wherein the naturally derived tobacco extract comprises at least about 0.1 percent by weight nicotine.
19 . The method according to claim 1 , wherein the concentrated tobacco extract comprises less than about 70 micrograms/gram acetaldehyde.
20 . The method according to claim 1 , wherein the concentrated tobacco extract comprises less than about 14 micrograms/gram formaldehyde.