Classifications

• • A—HUMAN NECESSITIES
  • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
  • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
  • A24B3/00—Preparing tobacco in the factory
  • A24B3/18—Other treatment of leaves, e.g. puffing, crimpling, cleaning
  • A24B3/182—Puffing

Definitions

• ABSTRACT Tobacco having at least 6 percent moisture is impregnated with ammonia and carbon dioxide to introduce into the tobacco preferably from about 3 percent to about 6 percent by weight of ammonia and from about 2 percent to about 8 percent of carbon dioxide based on the weight of the tobacco.
• the tobacco is thereafter heated at a temperature of from 250 F to about 700F for a time sufficient to puff the tobacco.
• a patent to Hawkins, U.S. Pat. No. 1,789,435 granted in 1931 describes a method and apparatus for expanding the volume of tobacco in order to make up the loss of weight caused in curing tobacco leaf.
• the cured and conditioned tobacco is subjected to air, carbon dioxide or steam under pressure and then on release of pressure the tobacco tends to expand.
• the patent states the volume of the tobacco is increased to the extent of about 515 percent.
• a patent to Hind granted in 1969, U.S. Pat. No. 3,425,425 also relates to the use of carbohydrates to improve the puffing of tobacco stems.
• tobacco stems are soaked in an aqueous solution of carbohydrates and then heated to puff the stems.
• the carbohydrate solution may also contain organic acids and- /or certain salts which are used to improve the flavor and smoking qualities of the stems.
• the present invention relates broadly to the puffing of tobacco with a relatively inexpensive, low combustibility, volatile and nontoxic agent and more particularly to the production of a puffed tobacco product of substantially reduced density produced by impregnating tobacco with ammonia and carbon dioxide and then subjecting the impregnated tobacco to expansion conditions such as heat, or reduced pressure or both, or to other known radiant energy conditions as previously mentioned.
• the tobacco to be impregnated may have a particle size of about 20 to 5 mesh, but preferably not less than about 30 mesh.
• the material treated' may be in rel atively dry form, or may contain the natural moisture content of tobacco.
• the tobacco should have at least about 6 percent moisture but less than 35 percent moisture. The reason for the upper limit will be provided in the further description of the invention.
• the essential feature of the invention process is the expansion or puffing of the tobacco utilizing ammonia and CO as the primary expanding agents. It is believed that the ammonia under .the conditions of operation and possibly in the presence of some moisture, causes the expansion of the tobacco to a greater and less reversible extent than can be obtained with various other expanding agents.
• the pretreatment of tobacco may be with liquid or gaseous ammonia or with ammonium hydroxide to permit absorption of ammonia into the tobacco cellular structure.
• a preferred method is to introduce both ammonia and carbon dioxide into the tobacco or by contacting tobacco'with either ammonium carbonate or ammonium bicarbonate applied directly, or formed insi'tu by the reaction of ammonia with carbon dioxide and moisture in the tobacco. In any of the procedures indicated, substantial expansion takes place on heating the impregnated tobacco either by means of the ammonia alone or the combined effects of both ammonia and carbon dioxide within the tobacco structure.
• the treatment of tobacco with ammonia may be by direct contact with liquid ammonia, solutions of ammonia, ammonia vapor or by substances capable of evolving ammonia such as by incorporating ammonium carbonate or bicarbonate in the tobacco to be treated. Sufficient time is provided to result in impregnating at least 1 percent by weight of ammonia or its equivalent into the tobacco cell structure for acceptable expansion, with 2.5 percent to 8 percent by weight absorbed being preferred.
• dure is to use liquid ammonia applied in a form of a spray, followed by a period of stabilization or equilibration of a'few minutes to 24 hours to effect the desired absorption and retention of the agent in the tobacco.
• Substantial addition of ammonia to the tobacco may thus be reached, amounting to as much as 100 percent by weight.
• a thorough spraying for five minutes is satisfactory requiring no further standing, with about 50 percent absorption being achieved.
• liquid ammonia Another method in the use of liquid ammonia is to dip the tobacco into liquid ammonia for a period of one to two minutes followed by draining and standing or re taining the treated tobacco in a closed vessel up to two to four hours. This will result in about eight to about 12 percent absorption. Satisfactory absorption may be achieved by dipping the tobacco into liquid ammonia for about five minutes and merely draining the tobacco on withdrawal. By this procedure about 50 percent of ammonia is absorbed. Concentrated ammonium hydroxide may alternatively be used as a substitute for liquid ammonia, the tobacco being held therein for about one to two minutes.
• Ammonia vapor may also be used, for example, by exposing the tobacco to ammonia vapors from an aqueous solution of ammonia (ammonium hydroxide) for a period of one hour to one week but preferably from about four to 24 hours which results in an ammonia intake of from 1 percent to about 12 percent by weight with additional intake of some moisture.
• ammonia ammonium hydroxide
• the impregnated tobacco should not be exposed to the air for more than a few minutes before puffing, so that undesirable darkening is avoided.
• the tobacco can be impregnated with from 1 percent to as high as 50 percent by weight ammonia depending on the partial pressure of the ammonia vapor over the aqueous ammonia. As indicated previously, about 2.5 to 8 percent ammonia impregnation is preferred.
• Th amounts and rates of absorption are determined by the rates at which heat can be dissipated from the mass of tobacco undergoing treatment and the final temperature attained since there is an exothermic heat of solution and reaction of the ammonia, carbon dioxide and the moisture in the tobacco. It is therefore best to keep the temperature of the tobacco undergoing absorption at a reasonably low point, below about 100F. and preferably in the neighborhood of about 75F. by cooling, to achieve satisfactory absorption and formation of ammonium carbonates in the tobacco.
• An alternative method employs ammonium carbonate or ammonium bicarbonate for supplying both ammonia and carbon dioxide as expansion agents for tobacco.
• One procedure for obtaining impregnation of these compounds is to subject the tobacco in an enclosed zone from 24 to 96 hours to the ammonia and carbon dioxide gas that is given off or released from the ammonium carbonates, permitting these gases to be absorbed and to react with the moisture present to form ammonium carbonates.
• Penetration of the gases and formation of ammonium carbonates in the tobacco is expedited if the tobacco impregnation chamber is first evacuated. Pressures ranging up to 26 in. of Hg absolute may be used. Absorption is enhanced by cooling the contents to hold the temperature of the tobacco below about 100F. Following the impregnation, completed when the temperature is in the neighborhood of about F., the tobacco is held for about 15 minutes to one hour before the final puffing step.
• Still another procedure is to utilize ammonium carbonate or ammonium bicarbonate in the form of a dust applied to tobacco leaf in an amount of about 1-25 percent by weight of the tobacco.
• the treated tobacco is then held for about 18 to 96 hours but preferably about 24 hours is sufficient for equilibration and retention of about four to eight percent of the carbonates within the tobacco structure.
• a still further method for impregnating tobacco with ammonium carbonate or bicarbonate is to contact the tobacco with these salts suspended or partially dissolved in a suitable liquid medium for about 1 to 48 hours, permitting the carbonates to be absorbed along with some absorption of the liquid medium itself.
• suitable liquid medium for about 1 to 48 hours, permitting the carbonates to be absorbed along with some absorption of the liquid medium itself.
• liquid carriers or solvents that may be used are methylene chloride or highly concentrated methanol or ethanol aqueous solutions comprising about 75 to percent alcohol.
• the liquid solvent or carrier may be removed in good measure by exposing the tobacco to a flow of inert gas or air before puffing.
• ammonium carbonate or bicarbonate is the fact that these compounds easily decompose at temperatures quite substantially below the charring temperature of tobacco.
• a still further advantage is that the treated tobacco need not be expanded immediately but may be stored or handled for short periods in air without loss of puffing capacity.
• the impregnated tobacco is then exposed to expansion conditions by subjecting the treated product to heat or the equivalent, or to reduced pressure or a combination of these effects.
• This may comprise the use of hot surfaces, or a stream of hot air, a mixture of gas and steam, or exposure to radiant energy such as radiant microwave energy or infrared radiation.
• Another method for causing expansion after the ammonia treating step is to subject the treated leaf toa sudden decrease in pressure as for example in guns such as are commonly used for puffing cereals.
• a convenient means of expanding treated tobacco is to entrain it in a stream of heated gas, such as superheated steam, which serves to carry away the expelled ammonia which may subsequently be recovered for reuse.
• the impregnated tobacco at heating temperatures in the neighborhood of 700F., should not be exposed to such temperatures for longer than the time it takes for the tobacco particles to attain a temperature of about 285F., which is normally about 0.1 seconds.
• One method for causing the expansion of the tobacco cells is to use the radiation methods described in either U.S. Pat. No. 3,409,022 or No. 3,409,027.
• Another method involves the use of a heat gun such as the Dayton heat gun or the equivalent, operating at an exit air temperature of 375-650F. for a period of about 0.2 seconds to four minutes, the shorter times of course being given for the higher temperatures. In this operation, the tobacco never attains a temperature above about 285F., being cooled by the rapid evolution of gases.
• a dispersion dryer for example, one that is supplied either with steam alone or in combination with air.
• An example of such a dryer is a Proctor & Schwartz PB dispersion dryer.
• the temperature in the dryer may range from about 250-700F. with contact time in the dryer of about four minutes at the lowest temperature to about 0.1 to 0.2 seconds at the highest temperature. In general, a 0.1 to 0.2 second contact time is utilized when the hot gas temperature is 500-600F. or somewhat higher.
• other known types of heating means may be used as long as they are capable of causing the impregnated tobacco to puff without excessive darkening. It should be noted, that where a high percentage of oxygen is present in the hot gases, it will contribute to darkening, so that if a hot-steam mixture is employed, a high proportion (e.g., over 80 percent by volume) of steam is preferred.
• a measurement of the expansion effect produced in the tobacco by the above procedures may be carried out by determining the percentage of the product that floats on a specific low density liquid such as acetone,
• a density of the final puffed tobacco product in the range of 0.25 to 0.60g./cc. is preferred.
• EXAMPLE 1 Bright tobacco in the form of cut filler and having a moisture content close to 12 percent is sprayed with a mist of liquid ammonia for a period of five minutes.
• the flow rate of gas through a Proctor & Schwarz PB. dispersion dryer (attached at outlet to a cyclone separator) is set at 2200 ft/min., at a superheated steam/air mixture in a ratio (volume) of about 90/10.
• Inlet temperature is 550F.
• the treated filler is fed into the system and the estimated exposure time is two seconds.
• the product is well puffed and has color equivalent to that before treatment or slightly lighter.
• EXAMPLE 2 Cut filler weighing 15 g. was sprayed in a polyethylene bag with 10 ml. of aqueous ammonium hydroxide (30 percent N11 and left in the closed bag several days. With the dispersion dryer set at 2200 ft/min. su- 4 perheated steam/air (5:1 approx. volume ratio) flow, 525F and 420F at inlet and outlet, respectively, the filler was given two passes through the system for an estimated four-second exposure (after one pass it was still damp). The product was puffed and about percent floated on absolute ethanol.
• EXAMPLE Burley filler (moisture 12-15 percent) was sprayed with liquid ammonia for varying lengths of time, then exposed in a rotating wire cage to air from a Dayton heat gun at approximately 400F for one rninute, followed by one minute of air with the heat off. The degree of puffing was noted by the fraction of filler which floated on various solvents: ethanol, d. 0.794; petroleum ether, d. 0.733; hexane, d. 0.687. Results are shown in Table I.
• EXAMPLE 7 A 4.8 liter glass resin-flask was fitted with a chromelalumel temperature probe connected to a recorder, and with connections to sources of vacuum, gaseous C0,, gaseous ammonia and a vacuum gage. 40 grams of bright tobacco was placed in the container. A vacuum of inches (of mercury) was drawn or about 1/3 of an atmosphere absolute pressure and CO was introduced to a vacuum of 10 inches. Then ammonia was introduced to a vacuum of two inches. During the next 20 minutes, ammonium bicarbonate deposited in the tobacco causing a temperature rise of 11.7C. After two hours, the temperature had returned to ambient (26C) and the pressure had returned to 10 inches. The container was then filled with more C0, (to ambient pressure) and almost no further temperature change was observed.
• EXAMPLE 8 One hundred and ninety grams of flue cured tobacco at 7.7 percent moisture was stored for 72 hours with 68 grams of commercial ammonium carbonate at a partial pressure of 44 mm. The pressure rose to an equilibrium of 180 mm after a few hours. About nine grams of the carbonate sublimed, and a total of nearly six grams of ammonia and CO was found on the tobacco by analy- SlS.
• the treated tobacco from the above experiments was expanded in the dispersion dryer at 400 and 550F with 1.8 percent NH and 1.2% CO, produced in the tobacco, expansion densities found were 0.60 at 400F and 0.41 at 550F.
• EXAMPLE 9 Cut bright leaf filler was dipped in methylene chloride saturated with ammonium carbonate. It was exposed for two days to the air. When this filler was placed on a hot plate, it puffed with some audible popping but without the more violent and irregular p0p ping observed with methylene chloride. Most of the solvent had apparently been lost before the pufiing.
• EXAMPLE 10 In equipment like that used in Example 7, 40 grams of E-7 bright tobacco filler was evacuated and exposed to ammonia vapor at atmospheric pressure. After about 30 minutes the tobacco was removed and subjected to steam/air (/10) in the dispersion dryer at an inlet temperature of 500F. approx. Density was found to be 0.27g./cc. as compared with 1.14g./cc. for the filler before treatment.
• EXAMPLE 1 1 Fifty pounds of filler-cut flue-cured tobacco at 11 percent (dry basis) moisture was charged to a large tumbler cooled by water at 42F. The tumbler was set in motion at 6 RPM and evacuated to about one inch Hg (absolute pressure). Then, four pounds of liquid ammonia was injected in a period of 10 mins., followed by six pounds of CO (gas) during a period of 30 mins. The use of liquid rather than gaseous ammonia greatly reduced the amount of heat evolved when tobacco is ammoniated. The residual vacuum was then discharged by admitting air. The impregnated tobacco was analyzed and contained 4.4% NH 5.3% CO and 18.6 percent (dry basis) total oven volatiles. It was injected into a high velocity turbulent stream of combustion gases and steam at 500F. and yielded a low density (0.28), (The density was measured by an acetone displacement method.) light yellow-colored, expanded product.
• this material When equilibrated after treating in a fine water spray to 13 percent moisture, this material showed a filling index about twice as great as untreated tobacco at a similar moisture content.
• ammonia is naturally present in tobacco but obviously at levels substantially below that needed for significant expansion.
• ammonia is a natural constituent of tobacco is a material advantage in carrying out the puffing process of the invention as described here.
• Ammonia also has the advantage of being relatively much less hazardous in forming explosive mixtures with air than would be encountered if one used some of the organic liquids that have been previously suggested.
• Ammonia is especially efficacious in causing puffing of tobacco parts because first it readily penetrates the cell walls and second at least in the presence of moisture is believed to have a softening effect on the cell structure which facilitates the puffing. Moreover, its low boiling temperature (vapor pressure) makes possi- Me the use of relatively low puffing temperatures. A further advantage is the relatively low cost of ammonia which means that losses due to incomplete recovery are of no great concern.
• ammonium carbonate or bicarbonate are compounds not only have negligable explosion hazard as compared to other substances but also have the advantage of producing ammonia and carbon dioxide at relatively low temperatures whereas excessive darkening and charting temperatures could be incurred with other substances capable of furnishing a gaseous puffing agent but only at a relatively high decomposition temperature.
• tobacco puffed with ammonia that is either absorbed or produced in situ shows little or no darkening in the absence of an excess amount of moisture. The latter, of course, can be prevented by avoiding the deliberate addition of water as is sometimes believed necessary in prior processes.
• the process of puffing tobacco comprising the steps of contacting tobacco containing at least about 6 percent moisture by weight in an impregnation zone with ammonia and with carbon dioxide at or above atmospheric pressure to introduce into the tobacco from about 3 percent to about 6 percent by weight of ammonia based on the weight pressure below atmosphere of about 26 inches mercury absolute or less to absorb carbon dioxide into the tobacco and then puffing the impregnated tobacco by heating to 250 to about 700F for a time sufficient to puff the tobacco.
• the process of puffing tobacco comprising the steps of contacting tobacco containing at least about 6 percent moisture in an impregnation zone with from about 1 to 12 percent by weight of ammonia at a low pressure below atmospheric to absorb ammonia into the tobacco, then contacting the tobacco with carbon dioxide at a pressure below atmospheric to absorb carbon dioxide into the tobacco, the temperature of contact being significantly below 100, and then puffing the impregnated tobacco by heating to a temperature in the range of 250 700F.

Landscapes

• Manufacture Of Tobacco Products (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22083166

Family Applications (1)

Country Status (15)

Cited By (34)

Families Citing this family (3)

Citations (10)

• 1970
  • 1970-08-31 US US00068532A patent/US3771533A/en not_active Expired - Lifetime
• 1971
  • 1971-07-15 FR FR7125841A patent/FR2101709A5/fr not_active Expired
  • 1971-07-19 BE BE770221A patent/BE770221A/xx not_active IP Right Cessation
  • 1971-07-22 YU YU1930/71A patent/YU33927B/xx unknown
  • 1971-07-29 CA CA119,397A patent/CA947606A/en not_active Expired
  • 1971-07-29 FI FI712152A patent/FI50822C/fi active
  • 1971-08-03 IL IL37428A patent/IL37428A/xx unknown
  • 1971-08-05 ES ES393918A patent/ES393918A1/es not_active Expired
  • 1971-08-20 NL NL7111513.A patent/NL155442B/xx not_active IP Right Cessation
  • 1971-08-26 GB GB4013871A patent/GB1356411A/en not_active Expired
  • 1971-08-30 NO NO3204/71A patent/NO133304C/no unknown
  • 1971-08-30 DE DE2143388A patent/DE2143388C3/de not_active Expired
  • 1971-08-30 JP JP46066949A patent/JPS5233199B1/ja active Pending
  • 1971-08-31 CH CH1276971A patent/CH560519A5/xx not_active IP Right Cessation
  • 1971-08-31 SE SE11019/71A patent/SE369666B/xx unknown

Patent Citations (10)

Also Published As

Similar Documents