Tobacco – Tobacco treatment – Puffing
Patent
1996-03-29
1998-04-21
Millin, Vincent
Tobacco
Tobacco treatment
Puffing
131296, A24B 318
Patent
active
057408173
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to processing of smoking materials, particularly tobacco and tobacco substitutes.
In the tobacco industry it is well known to expand tobacco in order to increase its bulk volume. Increasing the bulk volume of the tobacco increases the filling power of the tobacco and, in addition, smoking articles incorporating a proportion of expanded tobacco produce less tar and contain less nicotine because the weight of tobacco is reduced.
There are many known methods of expanding tobacco. One of the methods uses carbon dioxide to expand the tobacco. In this process tobacco is soaked in liquid carbon dioxide under pressure, the pressure released to solidify the carbon dioxide and then subjected to a high temperature which sublimes the carbon dioxide. The tobacco cells expand by virtue of a rapid pressure increase in the interior of the cells.
In another method, organic solvents are used to impregnate the tobacco. The tobacco is then quickly subjected to temperatures at least 30.degree. C. above the solvent's boiling point. Again, this quick evaporation causes the cell walls of the tobacco to expand.
A further known expansion method involves the impregnation of tobacco with nitrogen under a high pressure which is generally over 10 MPa (100 bar). The tobacco is then decompressed and passed through a steam tunnel in which the temperature rises rapidly to about 90.degree. C. thereby causing the tobacco to expand.
GB 675292 describes a process for expanding tobacco in which the tobacco is first freed from air and the air replaced by steam or water vapour. The treated tobacco is heated with steam and the pressure is then reduced to expand the tobacco. Pretreatment to remove air from the tobacco appears to be essential to the process.
The present invention involves a process for expanding smoking material which does not require a pretreatment step to remove air. It has been found that the presence of air during the process leads to no deleterious effects and, therefore, that no pretreatment to remove air is necessary.
According to the present invention, there is provided a process for treating smoking material comprising heating smoking material having a moisture content of from 5 to 75% by weight at a temperature of from 70.degree. to 220.degree. C. at about or above atmospheric pressure in the presence of air and reducing the pressure on the heated smoking material at a rate sufficient to expand the smoking material.
The pressure on the smoking material is preferably reduced to from 0.1 to 50 kPa (1 to 500 mbar). This has been found to give good expansion of the smoking material.
The term "in the presence of air", as used herein, means that at least 2% air is present. The atmosphere in which the smoking material is heated may be 100% air or mixtures of from 2--100% air with other gases such as steam, carbon dioxide and nitrogen.
Advantageously, the smoking material can be heated by direct application of steam, either saturated or superheated. The smoking material is heated to a temperature in the range of from 70.degree. to 220.degree. C. under a pressure of from 0.1 to 2 MPa (1 to 20 bar), preferably in the range from 102.degree. to 160.degree. C. under a pressure of from 0.11 to 0.5 MPa (1.1 to 5 bar). Alternatively, the smoking material may be heated by exposure to other relatively hot gases or radiant heat such as microwave radiation.
It is preferred that the pressure reduction to vacuum conditions is rapid and, typically, takes place in about 0.04 seconds. The process is well suited to expansion of tobacco and the bulk expansion may be in the range 20 to 100%.
Good results have been obtained where the smoking material has an initial moisture content of from 20 to 75% (more preferably 30 to 75% by weight) by weight and returns to near or below its original moisture content during the process, such as to a moisture content of up to 15% by weight. Surprisingly, by operating the process in this way the expanded smoking material retains its expanded state without requiring further treatment suc
REFERENCES:
patent: 4696313 (1987-09-01), Brown et al.
Imperial Tobacco Limited
Millin Vincent
LandOfFree
Processing of smoking material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Processing of smoking material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Processing of smoking material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2050991