Tobacco – Tobacco treatment
Patent
1998-07-22
2000-07-04
Silverman, Stanley S.
Tobacco
Tobacco treatment
131291, 131296, 131276, A24B 310, A24B 1500, A24B 318, A24B 1530
Patent
active
060823690
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for treating tobacco. More particularly, it relates to a process for expanding tobacco to increase its filling capacity.
Tobacco leaves, after harvesting, are subjected to curing processes. As a result of water loss suffered during the curing process, the leaves undergo variable shrinkage. It is conventional practice in the tobacco industry to treat cured tobacco intended for cigar or cigarette manufacture to recover the shrinkage by increasing its filling capacity. It is generally considered that by treating the tobacco in this way the cellular structure of the cured tobacco leaf is expanded to a state similar to that found in the leaf prior to curing.
A number of processes exist for increasing the filling capacity of tobacco. These are widely used within the industry to achieve product recovery after curing. The present invention is based on the discovery that filler expansion levels similar to and sometimes better than those achieved by conventionally used expansion processes and hence recovery can be achieved by the use of isopentane as the expansion medium in the vapour phase in a carefully controlled process.
Accordingly, the invention provides a process for treating tobacco comprising a series of steps: greater than 70 mbar (7 kPa); at temperatures in the range of 70.degree. C. to 90.degree. C. and maintaining the tobacco in contact with isopentane vapour at a pressure of at least 4 bar (400 kPa) for up to 30 minutes to cause impregnation of the tobacco structure; evacuating the chamber, the pressure change being effected adiabatically; and
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graphical representation of the results of Example 1 showing the pressure values employed within the process chamber during the course of treatment in accordance with the present invention.
FIG. 2 is a graphical representation of the results of Example 2 showing the pressure values employed within the process chamber during the course of treatment in accordance with the present invention.
FIG. 3 is a graphical representation of the results of Example 3 showing the pressure values employed within the process chamber during the course of treatment in accordance with the present invention.
FIG. 4 is a graphical representation of the results of Example 4 showing the pressure values employed within the process chamber during the course of treatment in accordance with the present invention.
The tobacco which is treated according to the process of the invention will typically be in the form of pieces of cured tobacco leaf obtained by threshing, flailing or slicing whole cured leaves. The tobacco may alternatively be in the form of strips cut from whole leaf or may be shredded leaf. The tobacco to be treated will be arranged in baskets in the processing chamber.
The cured tobacco is, according to the present invention, subjected to a reduced pressure of not greater than 70 mbar (7 kPa). By this treatment, air in the processing chamber and air retained in pockets between tobacco leaf pieces or within the cell structure which would otherwise interfere with the subsequent impregnation of the cellular structure by the isopentane vapour is removed. The use of reduced pressures above 70 mbar do not sufficiently remove occluded air in the tobacco and, as a result, the subsequent impregnation of the tobacco cellular structure by isopentane vapour is impaired. Preferably, the pressure in the chamber is reduced below 70 mbar (7 kPa) as far as it is possible to do so and this is, of course, dictated by the performance of the evacuation and recovery system used. We have found that pressures in the range of from 40-70 mbar (4-7 kPa) are consistently achievable in this process and give good results.
Isopentane vapour is then pumped into the processing chamber. It is important in the invention that no liquid isopentane is allowed to enter the process chamber. Therefore, liquid isopentane stored outside the process chamber must be completely vaporised before it enters the process chamber and come
REFERENCES:
patent: 3575178 (1971-04-01), Stewart
patent: 3683937 (1972-08-01), Fredrickson et al.
CRC Handbook of Chemistry and Physics, 66th edition, p. c-395, 1986.
Chard Brian C.
Henneveld Clifford H.
Matthews Keith A.
Nevett Robert
Imperial Tobacco Limited
Ruller Jacqueline A.
Silverman Stanley S.
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