MXPA98003007A - Process to treat - Google Patents

Abstract

The present invention relates to tobacco being treated to cause its expansion by a process which comprises the steps of subjecting to a reduced pressure not higher than 7 kPa, impregnating the cellular structure of the tobacco with isopentane vapor at temperatures of 70 to 90" C and keep the tobacco in contact with the steam at a pressure of at least 400kPa for up to 30 minutes, evacuate the excess steam, change the pressure is performed adiabatically, treat the impregnated tobacco with steam to expand the cellular structure of the tobacco and then subjecting expanded tobacco to vacuum re-ordering The levels of expansion achieved by the process are similar to and may be greater than those obtained using conventional expansion processes

Description

PROCESS TO TREAT TOBACCO DESCRIPTION OF THE INVENTION The present invention relates to a process for treating tobacco. In a more particular way, it is related to a process to expand the tobacco to increase its filling capacity. The tobacco leaves, after being harvested, are subjected to curing processes. As a result of the loss of water suffered during the curing process, the leaves undergo a variable contraction. It is a conventional practice in the tobacco industry to treat cured tobacco used for the manufacture of cigars or cigarettes to recover shrinkage by increasing its filling capacity. It is generally considered that by treating tobacco in this manner the cellular structure of the cured tobacco leaf expands to a state similar to that found in the sheet before curing. There are numerous processes to increase 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 levels of expansion of fillers similar to and sometimes better REF: 27255 can be achieved than those achieved by conventionally used expansion processes and consequently recovery by the use of isopentane as an expansion medium in vapor phase in a carefully controlled process. Accordingly, the invention provides a process for treating tobacco comprising a series of steps: (1) subjecting the tobacco to a chamber at a reduced pressure of not more than 70 mbar (7 kPa); (2) impregnating the cellular structure of the tobacco with isopentane vapor at temperatures in the range of 70 ° C to 90 ° C and keeping the tobacco in contact with the isopentane vapor at a pressure of at least 4 bar (400 kPa) during at least 30 minutes to cause the impregnation of the tobacco structure; (3) removing the excess of isopentane vapor from the impregnated tobacco by evacuating the chamber, the change in pressure is carried out adiabatically; (4) contacting the impregnated tobacco with steam to expand the tobacco; and (5) subjecting the expanded tobacco to reordering to vacuum. The tobacco that is treated according to the process of the invention is typically in the form of pieces of cured tobacco leaf obtained by threshing, beating or cutting complete cured leaves. The tobacco may alternatively be in the form of strips cut from the whole sheet or may be in the form of a milled sheet. The tobacco to be treated should be fixed in baskets in the processing chamber. The cured tobacco is, according to the present invention, subjected to a reduced pressure not higher than 70 mbar (7 kPa). For this treatment, the air in the processing chamber and the air retained in the cavities between the pieces of tobacco leaf or within the cellular structure which in other circumstances could interfere with the subsequent impregnation of the cellular structure by the isopentane vapor It is removed. The use of reduced pressures above 70 mbar does not sufficiently remove the air entrained in the tobacco and, as a result, the subsequent impregnation of the cellular structure of the tobacco by the isopentane vapor deteriorates. Preferably, the pressure in the chamber is reduced below 70 mbar (7 kPa) as much as possible and this is, of course, dictated by the operation of the used evacuation and recovery system. It has been found that pressures in the range of 40-70 mbar (4-7 kPa) are consistently achievable in this process and give good results.The isopentane vapor is then pumped into the processing chamber. invention that does not allow liquid isopentane to enter the process chamber.

Therefore, the liquid isopentane stored outside the process chamber must be completely evaporated before entering the process chamber and coming into contact with the tobacco. Since isopentane is a highly volatile and flammable solvent, the process engineering design and the recovery system must be carried out carefully. The temperature at which the isopentane vapor enters the chamber should be in the range of 70 ° C to 90 ° C. Isopentane vapor having a temperature greater than 90 ° C in the invention should not be used, since it worsens the subsequent steam expansion treatment and does not allow sufficient expansion of the tobacco to be achieved. In addition, if the heat exchanger graduates to produce isopentane vapor at a temperature lower than 70 ° C, there is a risk that liquid isopentane may pass through and enter the process chamber. The isopentane vapor at such a temperature can, upon entering the chamber, be cooled by the contents of the chamber to the degree that it condenses. The effect of allowing liquid isopentane in the process chamber is the interruption of the process. First, any liquid isopentane present in the chamber will absorb energy from the system as it evaporates. Secondly, the energy requirements of the recovery procedures of the excess of isopentane will increase.

The amount of isopentane that impregnates the cells in the tobacco leaf is controlled by the vapor pressure of iopentane created in the process chamber. The isopentane vapor is injected into the chamber until an internal pressure of at least 4000 mbar (400 kPa) is reached, preferably in the range of 4000 - 4500 mbar (400 - 450 kPa). When this pressure value is reached, the chamber is sealed after which the internal pressure will continue to rise (typically up to about 5000 mbar) as the temperature of the isopentane vapor continues to rise. with isopentane vapor at a pressure of at least 4000 mbar (400 kPa) for up to 30 minutes to allow complete penetration of the tobacco leaf cells by isopentane, it has been found that optimal tobacco expansion is achieved maintaining the pressure high for approximately 30 minutes During the impregnation phase, it is assumed that the isopentane that appears inside the cell structure is pressed under pressure in the liquid phase.As soon as this period of time has passed all the isopentane vapor in the excess is removed from the chamber by reducing the pressure in the chamber as quickly as possible, preferably at a pressure close to the The pressure change is, in this way, adiabatic. By ensuring an adiabatic pressure change, the disruption and breakdown of the cell structure that could be catastrophic is avoided. It has been found that this pressure reduction can be achieved in less than 15-20 minutes, typically around 15 minutes. Immediately after the evacuation of the chamber, the temperature of the impregnated tobacco is increased rapidly by bringing the tobacco into contact with the vapor. As a consequence of the increase in temperature, the liquid isopentane bound within the tobacco leaf cells undergoes an increase in volume and is released causing the cellular structure of the tobacco to expand. Electron microscopy reveals that cell walls swell as a result of this treatment. In addition, the surface of the sheet seems to wrinkle. Typically, the steam is introduced into the chamber to raise the pressure therein to a value in the range of 1000 mbar (100 kPa) to 1400 mbar (140 kPa) and preferably 1000 to 1200 mbar (100 to 120 kPa) . Care should be taken with the addition of steam to avoid turbulence inside the chamber, which could have a damaging effect on the expansion of the tobacco. Preferably, the expansion step is considered complete when the steam removed from the chamber by the evacuation and recovery system has been raised to a temperature of 90 to 95 ° C especially around 94 ° C. At this point, the introduction of steam is discontinued. The period of time from the start of the steam introduction to achieving its exhaust temperature should preferably be no more than 4 minutes and, if possible, no more than 2 minutes. Immediately after completing the expansion stage, the expanded tobacco is subjected to the rearrangement by evaporation to achieve the desired final expansion and moisture content. Typically, the final moisture content of the tobacco should be as close as possible to the level prior to the process. The rearrangement can, in general, be achieved by evacuating the process chamber, after completing the expansion stage, at a pressure in the range of 180-220 mbar (18-22 kPa). Subsequently, the pressure returns isothermally to atmospheric pressure and the expanded tobacco is removed from the process chamber. The thus treated tobacco can then, if it is required to be mixed in the usual way and then be transported to the cigar or cigarette production site as required. To measure the filling value of a cured tobacco product, cured, threshed, as described in the following examples, a filling value apparatus is used, which is essentially composed of a 64 mm diameter cylinder in which a 63 mm diameter piston slides. The piston has a graduated seal on the sides. Pressure is applied to the piston and the volume is determined in milliliters of a given weight of tobacco, 14.18 g. Experiments have shown that this apparatus will accurately determine the filling value of a given amount of tobacco for threshed cigar with good reproducibility. The pressure on the tobacco applied by the piston in all the experiments was 12.8 kPa applied during 10 minutes, at which time the filling value reading was taken. The moisture content of the tobacco affects the filling values determined by this method, therefore, comparative filling values obtained at similar moisture contents were obtained.

Example 1 150 kg of a milled, milled cigar, with a content of 14 to 14.5% humidity and having a filling value of 5.08 cc / g when determined by the procedure indicated above were fixed in baskets and treated accordingly. to the process of the invention. The tobacco was subjected to reduced pressure of 64 mbar (6.4 kPa) and isopentane vapor in the range of 70 ° C to 90 ° C and was then pumped into the process chamber by raising its pressure to 4300 mbar (430 kPa). The tobacco remained in contact with the isopentane for 30 minutes, at which time the pressure was raised to 4964 mbar. All excess isopentane vapor was removed from the chamber by adiabatically reducing the pressure to 1100 mbar (110 kPa) for a period of about 6 minutes. After this evacuation, steam was injected into the process chamber until the steam removed from the chamber by the evacuation and recovery system was raised to 104 ° C. The reordering by evaporation by additional evacuation of the chamber at a pressure of 200 mbar (20 kPa) was finally for the reestablishment of the atmospheric pressure and the removal of the expanded tobacco from the process chamber. The final filling value of the tobacco was 8.14 cc / g and the moisture content from 14% to 14.5%. The procedure of Example 1 was repeated in additional cycles of tobacco and the results were noted in Table 1. The process parameters for Examples 2, 3 and 4 were the same as for Example 1 unless otherwise stated. The pressure values employed within the process chamber during the entire treatment period according to Examples 1 to 4 are shown graphically in Figures 1 to 4, respectively.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (6)

1. A process for treating tobacco, characterized in that it comprises a series of steps: (1) subjecting the tobacco to a chamber at a reduced pressure not higher than 70 mbar (7 kPa); (2) impregnating the cellular structure of the tobacco with isopentane vapor at a temperature in the range of 70 ° C to 90 ° C and keeping the tobacco in contact with isopentane vapor at a pressure of at least 4 bar (400 kPa) during up to 30 minutes to cause the impregnation of the tobacco; (3) remove the excess isopentane vapor from the impregnated tobacco by evacuating the chamber, the pressure change is made adiabatically; (4) put in mind the steam impregnated tobacco to expand the tobacco; and (5) subjecting expanded tobacco to a reordering process.

2. The process according to claim 1, characterized in that in step (1) the tobacco is subjected to a reduced pressure in the range of 40-70 mbar (4-7 kPa).

3. The process according to any of claims 1 or 2, characterized in that in step (2) the tobacco is kept in contact with the isopentane vapor at a pressure in the range of 4000 - 4500 mbar (400 - 450 kPa) per approximately 30 minutes.

4. The process according to any of claims 1 to 3, characterized in that in step (4) the steam is introduced into the chamber to raise the pressure to the value of from 1000 to 1400 mbar (100 - 140 kPa).

5. The process according to claim 4, characterized in that the introduction of steam into the chamber is discontinued when the temperature of the exhaust steam leaving the chamber reaches 90-95 ° C, especially around 945C.

6. The process according to any of claims 1 to 5, characterized in that the reordering process comprises subjecting the expanded tobacco to vacuum drying at reduced pressure in the range of 180-220 mbar (18-22 kPa).