US3683937A

US3683937A - Tobacco expansion process

Info

Publication number: US3683937A
Application number: US101440A
Authority: US
Inventors: James D Fredrickson; Ella Sue Hickman
Original assignee: Reynolds Leasing Corp
Current assignee: Arjay Holdings Inc
Priority date: 1970-12-24
Filing date: 1970-12-24
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15

Abstract

The filling capacity of tobacco is increased by contacting tobacco with the vapors of a volatile organic solvent which is inert to the tobacco and has an atmospheric boiling point of between - 50* and 80* C. The tobacco treated is free of any liquid or solid form of the solvent when contacted by the vapors and is maintained at a temperature above the boiling point of the said compound at the pressure prevailing during the contacting. Thereafter, without cooling the tobacco below the said boiling point, the pressure is rapidly reduced or the temperature rapidly increased to provide vapor releasing conditions and expansion of the tobacco.

Description

United States Patent Fredrickson et al.

[ 1 TOBACCO EXPANSION PROCESS [72] Inventors: James D. Fredrickson; Ella Sue Hickman, both of Winston-Salem,

[73] Assignee: Reynolds Leasing Corporation,

Jacksonville, Fla.

[22] Filed: Dec. 24, 1970 21 Appl. No.: 101,440

[52] US. Cl. ..131/140 P, 131/143 [51] Int. Cl. ..A24b 03/18 [58] Field of Search ..131/17, 140-144; 34/5 [5 6] References Cited UNITED STATES PATENTS 1,789,435 1/1931 Hawkins ..131/140 P UX 3,144,871 8/1964 De Souza etal ..131/140P 3,524,451 8/ 1970 Fredrickson ..131/140 P 3,575,178 4/1971 Stewart ..131/140P [151 3,683,937 1451 Aug. 15, 1972 FOREIGN PATENTS OR APPLICATIONS 955,679 4/1964 Great Britain ..131/140 P Primary Examiner -Melvin D. Rein Attomey-Pendleton, Neuman, Williams & Anderson [57] ABSTRACT The filling capacity of tobacco is increased by contacting tobacco'with the vapors of a volatile organic solvent which is inert to the tobacco and has an atmospheric boiling point of between 50 and 80 C. The tobacco treated is free of any liquid or solid form of the solvent when contacted by the vapors and is maintained at a temperature above the boiling point of the said compound at the pressure prevailing during the contacting. Thereafter, without cooling the tobacco below the said boiling point, the pressure is rapidly reduced or the temperature rapidly increased to provide vapor releasing conditions and expansion of the tobacco.

17 Claims, No Drawings BACKGROUND OF THE INVENTION This invention relates to a processof treating tobacco and has for an object the provision of a process for increasing the filling capacity of a tobacco product.

Tobacco leaves when harvested contain a considerable quantity of water and during the normal tobacco curing process this water is removed by drying, resulting in shrinkage of the leaf structure. In the usual process of preparing tobacco for storage and sub sequent cigar or cigarette manufacture, the tobacco regains very little, if any, of the shrinkage resulting from the drying step so that a significant loss in the filling capacity of the tobacco is the result. Thus, the cured tobacco has a bulk density which is in excess of that required for making satisfactory cigarettes or cigars. Also, during cutting of leaf or strips for making cut filler for cigarettes, frequently the shreds are laminated together to form hard, dense particles which occupy far less volume than the original shreds occupied. This is wasteful since these hard compacted shreds are not necessary in the tobacco to produce an article which is satisfactory for smoking.

Several procedures have been suggested in the prior art for increasing the normal filling capacity of tobacco. Certain of these procedures have involved puffing operations in which the tobacco is subjected to high pressure steam, followed by sudden release of pressure. Such processes have not usually been satisfactory since they result in the production of excessive amounts of fines. Also, it has been suggested that the filling capacity of tobacco may be increased (i.e., bulk density reduced) by exposing the tobacco to the vapors of an organic liquid to condense the liquid in the tobacco followed by air drying at ambient temperatures and pressures. However, such procedures have not been wholly satisfactory because they are not effective for increas ing the filling capacity to any great extent. Another method that has been proposed involves contacting the tobacco with a volatile organic liquid and then heating the liquid-impregnated tobacco to a temperature above the boiling point of the liquid whereby to vaporize the liquid directly in the tobacco causing expansion. Embodiments of this last mentioned procedure are described in US. Pat. Nos. 3,524,45 1' and 3,524,452 issued Aug. I8, 1970.

Another object of this invention is the provision of a tobacco treating process which involves the use of vapors or an organic compound.

A further object of this invention is the provision of a process for increasing the filling capacity of tobacco under conditions such that the process can be readily controlled to produce the desired product.

An additional object of this invention is the provision of a process for expanding tobacco using vapors of an organic compound thereby eliminating the requirement of handling large quantities of liquid in commercial operations.

A still further object of this invention is the provision of a process for increasing the filling capacity of tobacco which may be readily adapted to a continuous operation.

Further and additional objects will appear from the following description and the appended claims.

2 GENERAL DESCRIPTION OF THE INVENTION In accordance with one embodiment of this invention, a process is provided in which a tobacco product is contacted withvapors of an organic compound or mixture of organic compounds in the absence of the liquid or solid phases thereof, said contact being effected while maintaining the temperature of the tobacco above the boiling point of the compound or mixture of compounds at the prevailing pressure. In this step the vapors are adsorbed onto or absorbed directly into the tobacco particles. Thereafter the tobacco is subjected to vapor releasing and expanding conditions by suddenly decreasing the ambient pressure and/or by rapidly heating the impregnated tobacco whereby to release and expand the vapor. The resulting tobacco has a lower bulk density (i.e., higher filling capacity) than the untreated tobacco charged to the process and is suitable for use in the manufacture of smoking tobacco articles such as cigarettes, cigars, pipe tobacco and the like.

The tobacco to be treated in accordance with the process of this invention is preferably a cured tobacco and may be in the form of shreds, strips, leaves, stems or sheets of reconstituted tobacco. However, the process is easier to control and the best results are obtained if tobacco shreds are used. This is for thereason that usually shreds are relatively easy to handle in continuous procedures and the final product of the process need not be-subjected to shredding as may be necessary for cigarette manufacture. Shredding of the final product results in compressing the product which tends to destroy the ultimate objective of the process of this invention, namely, to expand the tobacco and eliminate compressed particles, as may have resultedfrom prior treatment including shredding. Any type of tobacco may be used in the practice of this invention and it is particularly useful for the processing of burley, fluecured and Oriental (e. g., Turkish) tobaccos.

Hurley and flue-cured tobaccos. used in the manufacture of cigarettes ordinarily have a moisture content of about 10 to 20 percent by weight. In the practice of this invention, the moisture content of the tobacco when contacted with the organic vapor is preferably in excess of 8 percent by weight and suitably within the range of 10 to 30 percent. The desired moisture content may be dicated percentage of moisture is desired since the intemal structure of the tobacco is thereby rendered suf ficiently pliable or flexible to permit the expansion or pufiing when the vapors of the organic compound expand within the tobacco upon pressure reduction or heating. If the moisture content is less than 8 or [0 percent, the process results in the production of an excess of tobacco fines during the expansion step. A tobacco having greater than about 30 percent moisture has a tendency to be mushy or soggy and is difficult to handle in commercial operations.

In accordance with this invention, the moist tobacco is contacted with the vapors of the organic compound in the absence of the liquid on solid phases under conditions which effect impregnation of the tobacco with the vapors. It is sometimes preferred, particularly if a low boiling organic compound is used, that the tobacco be subjected to a partial vacuum or a short period of time before vapor impregnation. This operation serves to remove at least a portion of air or other gas that may be occluded within the tobacco particles or between the fibers thereby permitting more complete vapor impregnation and absorption or adsorption of vapor on the tobacco particles. The tobacco during vapor impregnation is maintained at a temperature above the boiling point of the organic compound at the prevailing pressure. Preferably, the temperature of the body of tobacco is maintained at least l C. above said boiling point. The vapor impregnation step may be carried out at any convenient ambient pressure, atmospheric pressure being preferred in commercial operations. However, the impregnating pressure will, in part, depend upon the boiling point of the particular compound which, in the vapor phase, is used for the impregnation. Also, it is preferred that the temperature of the tobacco during the impregnating step be less than about 100 C. so that no adverse effect is produced on the tobacco undergoing the treatment. When using vapors of a compound having an atmospheric pressure boiling point above room temperature it will be necessary to carry out the impregnation at elevated temperatures and/or reduced pressures. During impregnation the vapors enter into the minute spaces between and within the tobacco particles and become absorbed and/or adsorbed on the particle surfaces. With vapors of the lower boiling organic compounds, the impregnation may be effected with the tobacco maintained at ordinary room temperature. The impregnating vapors may contact the tobacco by subjecting it to an atmosphere containing in excess of 2 percent and preferably in excess of 5 percent by volume of the vapors over a period of time such that a substantial amount of vapors permeates into the tobacco and becomes adsorbed or absorbed by the tobacco particles. Under certain conditions, as in the case of the highly volatile Freons (i.e., fluorinated hydrocarbons), the water-moistened tobacco may be exposed to an atmosphere consisting essentially of the vapors of the fluid at atmospheric temperature and pressure in order that the vapors may find their way directly into the tobacco during treatment. The amount of non-aqueous vapor used for impregnation is critical to the extent that sufficient vapor should be present as the free vapor or in the adsorbed or absorbed states so that when expanded a significant expansion of the tobacco will occur. The amount to be used will depend upon the chemical compound whose vapors are utilized, the concentration of the vapors in the impregnating atmosphere, the time of contact for impregnation, the degree of tobacco expansion desired and the processing temperatures and pressures. In other words, it is important that the concentration of the organic compound vapor in the impregnating atmosphere be high enough and the exposure to the impregnating atmosphere be for a period sufficient to produce a treated tobacco which will expand adequate- 1y. To achieve this result the weight percentage of organic compound in the tobacco when subjected to the vapor expanding conditions is preferably in excess of about 5 percent by weight. This relatively high percentage is readily achievable by vapor phase impregnation because the vapors are strongly absorbed or adsorbed directly on the tobacco particles even though the temperature of the tobacco is above the boiling point of the compound at the prevailing pressure.

The compound employed for impregnating the moistened tobacco is one which is chemically inert to the tobacco being treated and has a boiling point at atmospheric pressure between about --50 and C.

Compounds having boiling points above +80 C. do not provide good tobacco expansion and are difficult to remove completely from the tobacco without adversely affecting its flavor and aroma. Compounds having very low boiling points (i.e., below 50 C.) are so volatile under readily obtainable pressures in commercial operations that the vapors are not impregnated into the tobacco to the desired degree at the time the vapor expanding conditions are applied. Preferably, the atmospheric pressure boiling point of the compound is between 40 and +40 C. Illustrative inert organic compounds are: ketones such as acetone and methyl ethyl ketone; aliphatic or cyclic ethers such as methyl ethyl ether, diethyl ether, diisopropyl ether, methyl butyl ether, dimethoxymethane, furan and tetrahydrofuran; aliphatic alcohols such as methanol, ethanol and 2-propanol; esters such as methyl formate, ethyl formate and methyl acetate; aliphatic hydrocarbons such as butane, pentane, isopentane, hexane and the corresponding unsaturated hydrocarbons; the cycloaliphatic hydrocarbons such as cyclobutane, cyclohexane and cyclopentane; the halohydrocarbons ethyl chloride, propyl chloride, isopropyl chloride, secbutyl chloride, t-butyl chloride, methyl bromide, ethyl bromide, t-butyl bromide, methylene chloride, chloroform, carbon tetrachloride, ethylene dichloride, ethylidene chloride; and the Freon liquids represented by trichloromonofluoromethane, dichlorodifluoromethane, monochlorodifluoromethane, 1 l -difluoroethane and trichlorotrifluoroethane. The organic materials that are preferred are the non-oxygenated compounds which are relatively non-polar in nature and are relatively or substantially immiscible in water. These preferred compounds as a group have relatively low specific heats and thus require only a low energy input to cause them to expand within the tobacco. Preferred materials are the hydrocarbons and the halogenated hydrocarbons of the types indicated above. Mixtures of vapors of several compounds may also be used if the boiling points of the liquid mixtures are within the indicated temperature range.

After the vapors have become thoroughly impregnated into the tobacco, the tobacco is then immediately and rapidly subjected to a vapor releasing and expanding condition whereby the vapors are released from the absorbed or adsorbed condition on the tobacco and the tobacco particles are expanded and puffed to the desired extent. This may be effected by a sudden increase in temperature or by immediately subjected the body of impregnated tobacco to a decreased pressure which may be accomplished by pressure release if the impregnation is carried out at superatmospheric pressure or by drawing a vacuum on the tobacco if the impregnation is effected at atmospheric or moderately superatmospheric conditions.

In the pressure release puffing procedure, the ambient pressure on the impregnated tobacco is reduced by at least 50 percent (e.g., from one atmosphere to less than one-half atmosphere) and preferably in excess of 75 percent and the reduction is accomplished rapidly, usually within a period of less than 1 minute and preferably in less than seconds. Also, the temperature of the tobacco at this point in time is still maintained above the boiling point of the organic compound at the decreased pressure so that vapor is released from the tobacco and expands. The tobacco is puffed and the vapors are expelled from the tobacco. Generally, it is only necessary to maintain this reduced pressure for a few minutes, after which time the tobacco retains its expanded condition even though subject to changes in pressure.

in the heat puffing procedure the vapor impregnated tobacco is rapidly heated, preferably by an increment of at least 25 C. within a period of less than 10 seconds, whereby the tobacco is puffed by release and expansion of the vapor due to temperature change without a corresponding increase in pressure. The puffing temperature should not exceed about 230 C. or the flavor and aroma of the tobacco may be adversely affected. The puffing temperature is achieved by heating in any desired manner such as radiant energy (e.g., microwave). However, it is preferred to use a stream of hot gas, such as air or steam, which serves not only to supply the puffing temperature but also to remove the released vapor of the organic material from the tobacco.

irrespective of the type of expansion process used it is desirable, at least with certain organic materials, to remove last traces of the vapors by passing a warm or hot gas through the expanded tobacco. The expanded tobacco is then reordered, if necessary, to the moisture content desired for the final product. This is usually carried out by wet steaming, spraying, etc., and the final moisture content is preferably within the range of 10 to 20 percent by weight. This tobacco product, having decreased bulk density, is particularly useful for the manufacture of smoking products such as cigarettes, cigars and pipe tobacco. The bulk density having been decreased, considerable savings in tobacco cost are obtained in the manufacture of these smoking products without sacrificing quality.

In order to measure the filling value or capacity of a cut filler tobacco product as described in the following examples, a measuring device was used which is essentially composed of a 100 milliliter graduated cylinder having an internal diameter of about 25 millimeters and a piston having a diameter of about 24 millimeters and weighing about 802.5 grams slidably positioned in the cylinder. A 3 gram sample of tobacco was placed in the" cylinder and the piston was positioned on it. The gravitational force exerted by the piston corresponded to a pressure of about 2.3 pounds per square inch. The filling value of the sample was the volume to which the 3 gram sample of tobacco in the cylinder was compressed after the weight of the piston had acted on it for a period of 3 minutes. This pressure corresponds closely to the pressure normally applied by the wrapping paper to tobacco in cigarettes. The moisture content of the tobacco affects the filling values determined by this method, therefore, comparative filling capacities of tobacco both before and after expansion were made with tobacco having essentially the same moisture contents.

For a more complete understanding of this invention, reference will now be made to several specific examples of procedures for carrying it into effect.

I EXAMPLE 1 Shredded flue-cured tobacco having a moisture content of about 1 1 percent and a filling value of 14.9 milliliters/3 grams was treated with additional water to raise the moisture contents to about 20 percent. The tobacco (20 grams) was then placed in. a flask and heated to a temperature of to C. by immersing the flask in a hot water bath. Thereafter, a stream of carbon tetrachloride vapor at about 77 C. was passed through the tobacco for 2 hours at atmospheric pressure. The temperature of the tobacco during this time was maintained between 80 and 85 C. (Le, above the boiling point carbon tetrachloride at the prevailing pressure). The vapor-impregnated tobacco was then immediately transferred to a wire basket in a steaming chamber without lowering the temperature to any significant extent and exposed to steam at atmospheric pressure and at about 1 10 C. for 5 minutes. After cooling and drying by exposure to air, the treated tobacco was reordered to the original moisture content of l 1 percent and the filling value of the tobacco was found to be 20.2 milliliters/3 grams representing an increase of about 36 percent over the original control.

EXAMPLE 2 Using essentially the same equipment and procedures specified in Example 1, shredded fluecured tobacco (20 grams) having amoisture content of about 12 percent by weight and having an initial temperature of about 30 C. was exposed to a stream of Freon-l1 (trichloromonofluoromethane) vapor for 2 hours at atmospheric pressure. The temperature of the tobacco during this time was maintained at 30 C. by means of the water bath. The vapor-impregnated tobacco was then transferred to the steam chamber and treated with steam at l051 10 C. for 1 minute. The moisture content of the tobacco was then adjusted to about 12 percent by equilibration for 24 hours in a desiccator containing a solution consisting of 3 parts of glycerin and 1 part of water. The filling value as a result of the treatment increased from 12.5 milliliters/3 grams for the control to 15.5 milliliters/3 grams representing an increase of about 24 percent.

EXAMPLE 3 Shredded flue-cured tobacco (20 grams) having a moisture content of about 11 percent by weight was placed in a stainless steel pressure reaction chamber equipped with a pressure gauge and an iron-constantan thermocouple. Freon-l 2 gas (dichlorodifluoromethane) was introduced into the reaction chamber under a pressure of 60 p.s.i.g. This pressure was maintained for 5 minutes during which time the temperature of the. tobacco remained between 10 and 20 C. The apparatus was then closed off from the Freon-l 2 source and was heated until the temperature of the tobacco increased to 30 C. and the internal ple representing a filling capacity increase of about 25 percent.

EXAMPLE 4 Shredded flue-cured tobacco (20 grams) having a moisture content of about 11 percent by weight was placed in a flask and exposed to reduced pressure corresponding to about 3 millimeters of mercury for a period of 2 minutes. The evacuated flask containing the tobacco was then immersed in an ice bath and vapors consisting essentially of Freon-12 were slowly introduced to return it to atmospheric pressure. The tobacco was exposed to a slow stream of Freon-l2 vapor at atmospheric pressure for an additional 15 minutes during which time the temperature of the tobacco remained at about C. as determined by a thermocouple placed in the tobacco mass. The flask containing the impregnated tobacco was transferred to a water bath at 50 C., and pressure within the flask was immediately reduced to 3 millimeters of mercury. This reduced pressure was maintained for minutes after which time the tobacco was returned to atmospheric pressure and cooled. Reordering of the treated tobacco and a control sample to about 12 percent moisture content and measuring the filling values revealed an increase of percent in the filling capacity of the treated sample over the control sample.

EXAMPLE 5 Shredded flue-cured tobacco having a moisture content of about 11 percent and a filling value of about 15.2 milliliters/3 grams was exposed to a stream of Freon-11 vapor for 2 hours at atmospheric pressure while maintaining the tobacco at a temperature of 30 C. The vapor-impregnated tobacco was then rapidly subjected to a reduced pressure corresponding to about 5 millimeters of mercury and was maintained at that pressure for approximately 15 minutes. This reduced pressure was accomplished in less than about 1 minute. After the vacuum was broken to the atmosphere the treated tobacco was reordered to about the original moisture content, to give a final product having a filling value of 17.8 milliliters/3 grams representing an increased filling capacity of about 17 percent.

EXAMPLE 6 The procedure of Example 2 was repeated except that the temperature of the tobacco during impregnation was maintained at 29 C. by means of the water bath and the impregnated tobacco was treated with steam at 140 C. for 1 minute to effect the expansion. The increase in the filling capacity of the tobacco as a result of this treatment was about 84 percent.

EXAMPLE 7 The procedure of Example 3 was repeated except that before vapor treatment the moisture content of the tobacco was increased to about 20 percent and the Freon-42 gas was introduced into the reaction chamber under a pressure of 65 p.s.i.g. The pressure was maintained for 5 minutes during which time the temperature of the tobacco remained between 16 and 18 C. The apparatus was then closed off from the Freon-l2 source and was heated until the temperature of the tobacco increased to 56 C. and the internal pressure of the apparatus was 202 p.s.i.g. After 20 minutes the pressure was quickly released by venting the apparatus to the atmosphere. After reordering to the original moisture content, the filling capacity of the tobacco was found to have been increased by 60 percent.

EXAMPLE 8 The process of Example 2 was repeated except that pentane vapors were employed and the tobacco during vapor impregnation was maintained at 38 C. Expansion was effected by passing steam at C. through the tobacco for 1 minute. The filling value of the original tobacco was 15.5 milliliters/3 grams and of the expanded tobacco was 27.0 milliliters/3 grams representing an increase of 74 percent.

EXAMPLE 9 A first sample (20 grams) of flue-cured tobacco was exposed'to a stream of Freon-l1 vapor in a l-liter 3- necked flask for 2 hours. The temperature of the tobacco was maintained at 29 C. by immersion of the flask in a water bath. The tobacco temperature was measured with an iron-constantan thermocouple inserted in the center of the sample. The source of F reon-l 1 vapor was disconnected from the flask and the tobacco heated rapidly by a stream of air from a heat gun which had been connected to one neck of the flask, The temperature of the hot air was C. The exposure time was 3 minutes. The puffed tobacco and an untreated batch of tobacco were reordered to the same moisture content by equilibration over 3:1 (w/w) glycerin-water in a desiccator for 41 hours. The filling value of the puffed sample after reordering was 20.2 milliliters/3 grams, and the filling value of the control tobacco 16.0 milliliters/3 grams. The increase in filling value was 26 percent. A second sample (20 grams) of the same fluecured tobacco was exposed to the hot air stream without prior treatment with Freon-11 vapor. After reordering, the treated tobacco had a filling value of 19.0 milliliters/3 grams and the control tobacco 17.0 milliliters/3 grams. The increase in filling value was 12 percent.

The foregoing examples are illustrative of processes in which the tobacco is treated in batches. However, the process of this invention is particularly adapted to a continuous operation. One such continuous operation is as follows:

EXAMPLE 10 A stream of shredded flue-cured tobacco having a moisture content of about 15 percent by weight is warmed to a temperature of 40 C. and continuously passed into a vapor impregnating chamber at a rate of about 1,000 pounds per hour. Vapors of Freon-ll gas at about the boiling point of the liquid (i.e., 23.8 C.)

are also passed into the impregnating chamber at a rate in excess of 50 pounds per hour. The chamber is maintained at essentially atmospheric pressure and at a temperature above the boiling point of Freon-11. The tobacco is advanced through the chamber on a suitable conveyor during which time the vapors impregnate the tobacco and are adsorbed or absorbed thereby. After a residence time of 2 to 10 minutes the stream of vapor impregnated tobacco having essentially the same weight ratio of tobacco and vapor charged to the chamber is discharged into a stream of gas which is heated to a temperature which is sufficient to raise the temperature of the impregnated tobacco by an increment of at least 25 C. within a period of less than about 10 seconds, suitably 150 C. This rapid heating releases and expands the adsorbed or absorbed vapors thereby resulting in expansion of the tobacco. The vapors are separated from the expanded tobacco and a first portion may be heated and recycledas the hot expanding gas and a second portion may be sent to a Freon-ll recovery system as described in US. Pat. No. 3,524,452. The tobacco is passed to a steam stripper to remove any residual Freon-ll and is reordered to the desired moisture content.

When applied to shredded tobacco, the product of the process of this invention is essentially freeof compressed laminated tobacco particles which are formed incident to the initial shredding of the tobacco used as a charge stock. The product may be used to manufacture cigarettes in the conventional manner or it may be mixed with other tobaccos to provide a desired blend for use in the manufacture of cigarettes or other smoking articles. The process requires only a minimum amount of organic compound. The vapor used for treating the tobacco in a continuous, semi-continuous or batch process can be recovered and recycled to the system if desired.

By maintaining the organic'compound in the vapor state, the ratio of tobacco to impregnating compound can be readily controlled in a continuous operation, extraction of soluble tobacco constituents by organic liquid. is avoided, and the migration of soluble constituents within the tobacco is minimized. The cost incident to the use and vaporization of excessive amounts of organic liquid within the tobacco is likewise avoided.

While particular embodiments of this invention have been described in the foregoing, it will, of course, be apparent that other modifications may be made without departing from the spirit and scope of this invention.

What is claimed is:

l. A process of increasing the filling capacity of tobacco which comprises contacting tobacco with vapors of an organic compound, said tobacco being free of the liquid or solid phase of said compound, said compound being chemically inert to said tobacco and having an atmospheric pressure boiling point between about -50 and C. and the temperature of said tobacco during said contacting being maintained above the boiling point of said compound at the pressure prevailing during said contacting, and thereafter, without cooling the resulting tobacco to a temperature below the boiling point of said compound at the prevailing pressure, subjecting the vapor-impregnated tobacco to vapor releasing and expanding conditions E fTRe $135538 gf c i i fir iivhich the compound is a relatively non-polar organic material substantially immiscible with water.

3. The process of claim 1 in which the compound is selected from the group consisting of hydrocarbons and halogenated hydrocarbons.

4. The process of claim 3 in which the compound is trichloromonofluoromethane.

5. The process of claim 3 in which the compound is dichlorodifluoromethane.

6. The process of claim 3 in which the compound is pentane.

7. The process of claim 3 in which the compound is isopentane.

8. The process of claim 1 wherein said atmospheric pressure boiling point is between. about 40 and +40 C 9. The process of claim 1 wherein the moisture content of the tobacco contacted. with the vapors is between about 10 and 30 percent by weight.

10. The process of claim 1 wherein the step of sub jecting the tobacco to vapor expanding conditions includes the step of rapidly reducing the ambient pressure on the vapor-impregnated tobacco.

1 l. The process of claim 10 in which the reduction in ambient pressure is at least 50 percent and is efiected over a period of less than about 1 minute.

12. The process of claim 1 wherein the step of subjecting the tobacco to vapor expanding conditions ineludes the step of rapidly increasing the temperature of the impregnated tobacco.

13. The process of claim 12 in which the temperature increase is at least 25 C. and is effected in less than about 10 seconds.

14. The process recited in claim 1 in which the amount of vapor in the tobacco when subjected to the vapor releasing and expanding conditions is at least 5 percent by weight.

15. The process of claim 1 wherein the temperature of the tobacco during said contacting is at least about 1 C. above the boiling point of said compound at the pressure prevailing during said contacting.

16. The process of claim 1 in which said tobacco is shredded tobacco.

17. The process of claim 1 in which the vapors are present in a gaseous atmosphere in a concentration in excess of 2 percent by volume.

Claims

2. The process of claim 1 in which the compound is a relatively non-polar organic material substantially immiscible with water.
3. The process of claim 1 in which the compound is selected from the group consisting of hydrocarbons and halogenateD hydrocarbons.
4. The process of claim 3 in which the compound is trichloromonofluoromethane.
5. The process of claim 3 in which the compound is dichlorodifluoromethane.
6. The process of claim 3 in which the compound is pentane.
7. The process of claim 3 in which the compound is isopentane.
8. The process of claim 1 wherein said atmospheric pressure boiling point is between about -40* and +40* C.
9. The process of claim 1 wherein the moisture content of the tobacco contacted with the vapors is between about 10 and 30 percent by weight.
10. The process of claim 1 wherein the step of subjecting the tobacco to vapor expanding conditions includes the step of rapidly reducing the ambient pressure on the vapor-impregnated tobacco.
11. The process of claim 10 in which the reduction in ambient pressure is at least 50 percent and is effected over a period of less than about 1 minute.
12. The process of claim 1 wherein the step of subjecting the tobacco to vapor expanding conditions includes the step of rapidly increasing the temperature of the impregnated tobacco.
13. The process of claim 12 in which the temperature increase is at least 25* C. and is effected in less than about 10 seconds.
14. The process recited in claim 1 in which the amount of vapor in the tobacco when subjected to the vapor releasing and expanding conditions is at least 5 percent by weight.
15. The process of claim 1 wherein the temperature of the tobacco during said contacting is at least about 1* C. above the boiling point of said compound at the pressure prevailing during said contacting.
16. The process of claim 1 in which said tobacco is shredded tobacco.
17. The process of claim 1 in which the vapors are present in a gaseous atmosphere in a concentration in excess of 2 percent by volume.