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
  • A24B15/00—Chemical features or treatment of tobacco; Tobacco substitutes, e.g. in liquid form
  • A24B15/10—Chemical features of tobacco products or tobacco substitutes
  • A24B15/12—Chemical features of tobacco products or tobacco substitutes of reconstituted tobacco

Definitions

• rejects comprise: small particles broken from the tobacco leaf during processing, usually called shorts; small particles of cut tobacco vein and rib usually called winnowings; and the midrib or stem of the tobacco leaf, notably Burley tobacco stem, which because of its undesirable smoking qualities is deliberately discarded.
• a primary object of this invention is to utilize tobacco stems along with other tobacco materials to produce sheets or other coherent forms of tobacco of good smoking qualities for incorporation in cigarettes, cigars, cigarillos and pipe tobacco.
• Another important object is to process tobacco stem to remove constituents deleterious to smoke taste and to convert the residual stem material to a homogenized pulp particularly well suited for use as the binding agent in making tobacco sheets and like coherent bodies with additional tobacco material in a comminuted state.
• a quantity of tobacco stems is subjected to aqueous extraction and homogenization to provide a pulp of cohesive properties to which a larger quantity (on a dry weight basis) of finely Patented July 10, 1962 ice to the smoking qualities of the final product is inordinately long in such case.
• the extraction vessel may be open to the atmosphere, it is desirable to use a scalable vessel suitable for operation at reduced and increased pressures.
• hammer mill or a disintegrator with a high-speed rotor divided tobacco material is added to yield a mixture that c is readily convertible to sheets and other coherent forms of tobacco by konwn techniques such as applying a layer of the mixture on a supporting surface and drying the layer to a removable film or sheet.
• the processing of tobacco stems pursuant to this invention involves two essential'steps: aqueous extraction to eliminate a substantial portion of the extractible components including undesirable alkaloids, such as nicotirie and nornicotine, and ash-producing salts, followed by homogenization of the residual stem material to yield a smooth pulp with cohesive properties.
• undesirable alkaloids such as nicotirie and nornicotine
• ash-producing salts followed by homogenization of the residual stem material to yield a smooth pulp with cohesive properties.
• the aqueous extraction of tobacco stems which may be aided by variations in temperature and pressure, is carried on generally for a sufiicient period to remove extractibles totaling from about 20% to 60% by weight (dry basis) of the original stems.
• the tobacco stems are usually cut to pieces of about A to /2 inch in length. The cut stems are then placed in an extraction apparatus, e.g., a wire-mesh basket that fits in vessel to which water is charged.
• the unusually high hydration of the homogenized pulp attainedwith a valve-type homogenizer is a noteworthy feature of this invention.
• the. homogenized pulp prepared from extracted tobacco stems is capable of functioning as binding agent for a quantity of finely divided tobacco material greater than the original quantity (on a dry weight basis) of tobacco stems.
• Tobacco sheets of adequate tensile strength and good smoking qualities are generally obtained by adding from 2 to 4 parts by dry weight of powdered'tobacco to each part by dry weight of the solids in the homogenized stem pulse.
• a ratio of about 3:1 dry Weights of powdered tobacco to stem pulp is often preferred.
• it is often advisable to enhance product tensile strength by adding a minor portion, usually less than 40% by weight, of the powdered tobacco to the residual stem material at the start or before the completion of the homogenization step.
• the powdered tobacco which is added as such to the homogenized stem pulp is obtained by dry-grinding shorts, winnowings and like tobacco material.
• humectants and plasticizers such as glycerol, sorbitol and various glycols are used, inqtobacco smoking products to avoid excessive drying and embrittlement of the tobacco prior to smoking.
• Humectants and plasticizers are desirably incorporated in the products of this invention at any point in the process after the tobacco stems have been extracted.
• Hume'ctants and plasticizers in an amount usually not exceeding about by weightand frequently not exceeding about 6% by weight of the dry-ground tobacco are-conveniently added to the homogenized stem pulp when the powdered tobacco is also combined therewith.
• 'Humectants and plasticizers may be even added to the final product of the invention by applying such materials, usuallyinaquous solution, as a coating or spray on the final product.
• the composite of homogenized stern pulp and dryground tobacco may be converted to a continuous tobacco sheet on a stainless steel conveyor belt equipped with a film applicator such as a reverse roll coater and with drying hoods, all as shown in U.S. Patent 2,747,583.
• a film applicator such as a reverse roll coater and with drying hoods, all as shown in U.S. Patent 2,747,583.
• the layer of aqueous binding agent and powdered tobacco applied on the conveyor belt is dried to an adherent film that is more readily removable from the belt after reordering, i.e., conditioning with moisture.
• U.S. Patent 2,747,583 demonstrates reordering of the adherent film with a fine water mist from a spray nozzle whichmay desirably be enclosed by a humidification chamber as illustrated in U.S. Patent 2,867,220.
• a spongy roller maintained continuously wet with water, may be disposed in rotating contact with the conveyor belt so that .the dry tobacco -film is moistened as it passes under the roller.
• humectants and plasticizers like glycerol may be admixed Withthe water used in reordering the tobacco film.
• the sheet is then removed or peeled from the conveyor belt and wound up as a roll of continuous tobacco sheet as shown in U.S. Patent 2,747,583. Often, .a doctor blade is used to facilitate parting of the tobacco sheet from the surface of the belt. Where the tobacco sheet is ultimately shredded for use in the manufacture of cigarettes or pipe tobacco, the sheet may be v tobacco leaves going into the cigarettes or pipe tobacco.
• continuous extraction may alternatively be performed in a vessel provided with means to maintain a substantially continuous flow of fresh water into the vessel. with a commensurate outflow of liquor.
• a circulating pump would be used in such case to effect a rapid circulation of liquor through the extraction vessel,
• continuous extraction may be achieved by adaptation of the continuous blow-down procedure used in conventional boiler practice.
• the residual stem material drained of extraction liquor, undergoes size reduction in the presence of added water in a wet hammer mill which maybe supplemented by an ultrasonic disintegrator wherein a high speed jet of the aqueous suspension of residual stem materials impinged on a thin steel reed in a tuned cavity.
• the aqueous suspension desirably has a consistency of about 2.5% to 3.0% by Weight (dry basis) of stem material.
• valve-type homogenizer for which the aqueous suspension is advisably adjusted With added Water to a lower consistency of say between 1.7% and 2.3% by Weight (dry basis) of stem material.
• the valve-type vhomogenizer is operated at a pressure of the order of 2000 p.s.i.g. or higher; a pressure of about 5000 p.s.i.g. is often preferred, Again, warming the aqueous suspension to a temperature in the range of about to 250 F. favors hydration of the residual stem material during passage through the valve-type homogenizer.
• aqueous suspension at the chosen elevated pressure enters a controlledmicroscopic clearance between the homogenizing valve and valve seat.
• the high pressure is instantaneously changed to high velocity so that the material passing through the clearance at extremely high velocity is subjected to high shear, extreme and intense turbulence, cavitation and impact.
• the impact action occurs as the material leaves the clearance and impinges on the impact ring surrounding the valve clearance.
• Liquid quantities aregiven in-terms of United EXAMPLE 1
• the recirculation pump was started. After 10 minutes of liquor recirculation, the blow-down pump was started up and hot water was added to maintain the original liquor level in the extraction vessel. Blow-down under vacuum with continuous hot water addition to hold the water level was carried out for an hour. The supply of hot water was then shut ofi as well as the vacuum pump and the blow-down pump. The vacuum was re leased and the steam pressure in the jacket adjusted to 50 p.s.i.g. Whenthe pressure in the vessel reached 23 p.s.i.g., the steam pressure in the jacket was lowered and thereafter adjusted to maintain a pressure of from 23 to 25 p.s.i.g. in the vessel. Pressurized cooking was continued for 30 minutes.
• the drained stem material was fed into the hopper of a screw conveyor and thence, with continual addition of water, into a series of wet hammer mills. Three hammer mills were used of successively decreasing screen size from inch to 0.006 inch.
• the aqueous suspension from the wet hammer mills was next passed 6 times through a valve-type homogenizer at a pressure of 5000 p.s.i.g. Water was added to the homogenized stem pulp to arrive at a final consistency of from 2.0% to 2.1% by weight of dry solids.
• Glycerol in the amount of 15.3 pounds was admixed with the pulp.
• the tobacco rejects which were ground to provide the tobacco flour were obtained partly from the leaf drying plant and partly from the cigarette factory and comprised both air-cured and flue-cured tobaccos.
• the mixture of homogenized pulp and tobacco flour was de-aired by spraying into a vacuum chamber, and then applied by means of a gated hopper as a wet coating of 0.045 inch in thickness, on a conveyor belt of stainless steel. The coating was dried with the aid of steam condensed on the bottom side of the belt, reordered and removed from the stainless steel belt with the aid of a doctor blade.
• the tobacco sheet thus produced was continuously slit and cut into small-rectangular pieces which were subsequently blended with leaf tobacco and converted into cigarettes by the conventional manufacturing technique.
• Cigarettes made with a tobacco blend containing 12% by weight of the shredded tobacco sheet were adjudged by smoking experts to have good smoking qualities, some experts even indicating a preference for these cigarettes over cigarettes made with the same tobacco blend but containing none of the shredded tobacco sheet.
• EXAMPLE 2 A 9.5 pound batch of Burley stems with 13% moisture content was chopped to pieces approximately inch in length. The chopped stems were placed in a vessel with a sealable lid having connections to a vacuum pump, a water line, a dip tube extending to the bottom of the vessel and having a strainer on its end, and a pressurized gas line. A gas ring was used under the vessel to heat the contents. A vacuum of 25 inches of mercury was applied for one hour. Then 5 gallons of Water were added and the whole charge boiled under vacuum for half an hour. Heating was discontinued, the vacuum line was closed and a pressure of 5 to p.s.i.g. was applied by introducing oxygen-free nitrogen into the vesselfor the purpose of ejecting the liquor through the dip tube.
• the charge was pressure cooked at 248 to 259 F. and 14 to 20 p.s.i.g. for one hour.
• the electrical conductivity is"expressed as the ratio of that of the liquor to that of a decinormal potassium chloride solution at 77F.
• the residual stem material (extraction loss approximately 50% by dry weight of original stems) was fed with addition of just sufi'icient water to maintain flow through a wet hammer mill fitted with a inch screen. It was then repassed through the mill after the principal screen had been changed to 0.027 inch.
• a centrifuge with four 10 milliliter cups was employed to subject 9 to 10 grams of the suspension at a temperature of 68 to 72 F. to a relative centrifugal force of 716 g (g being acceleration due to gravity) for 10 minutes.
• the centrifuge used had an effective radius of 7.1 centimeters and 3,000 revolutions per minute were required to produce the desired centrifugal force.
• the centrifuge tubes were weighed before and after adding the suspension, and were reweighed after centrifugation and pouring off the supernatant liquor.
• the water retention value, R was calculated from the following equation:
• the main portion of the aqueous suspension was then fed with added Water through a gear pump and an ultrasonic disintegrator, and given sev en complete passes through a valve-type homogenizer operating at 2000 p.s.i.g.
• the homogenized stem pulp thus produced amounted to pounds containing 2.17% by weight of dry solids.
• the pulp from the valve-type homogenizer was subjected to the Water retention value test and the following R values were obtained: 25.4, 24.8, 25.0, 24.5, with a mean value of 24.9.
• the increase of water retention value between the wet hammer milling stage and the homogenization stage (11.6 to 24.9) is quite striking.
• tobacco flour made from 5.1 pounds of shorts and 3.4 pounds of winnowings. All of this tobacco flour had been passed through a IOO-mesh screen. After admixing 0.25 pound of glycerol, the entire mixture was subjected tovacuum for half an hour in order to deaerate it.
• a portion of the deaerated mixture was cast upon a stainless steel belt traveling at 20 feet per minute and heated from the underside'iby steam at a gauge pressure of approximately half an inch of water. Casting was achieved by means at a gated hopper set with its forward blade 0.035 inch from the surface of the belt. Difiiculty was encountered in getting an even coating of the mixture on the belt and, therefore, water was added to the remainder of the mixture to give it a consistency of 1.75% by weight. This mixture of'lower consistency cast evenly as a wet coating of 0.035 inch in thickness, was dried and then rehumidified by means of a spongy roller receiving a constant drip of water rolling lightly over the surface of the tobacco sheet. A doctor blade of a laminated plastic material was used to remove the tobacco sheet continuously from the stainless metal belt.
• This sheet between 0.006 and 0.007 inch in thickness, was-cutinto small pieces and blended with leaf tobacco, the latter amounting to 8 8% by weight of the blend.
• the blend was cut on a conventional cutting machine and converted into cigarettes. These cigarettes were judged to be of pleasing smoke taste by a panel .of smoking experts familiar with cigarettes made solely with the same leaf tobacco.
• EXAMPLE 3 A '10,pound batch of Burley stems with a moisture content, cut to pieces about 2 inches in length, was placed in the extraction vessel of Example 2. A vacuum of inches of mercury was applied for one hour. The stem was given only one aqueous extraction of 4.5 hours with boiling under vacuum; toward the end of the extraction the vacuum had improved to '27 inches of mercury and the charge was boiling at 117 F. After ejection of the liquor, the residual stem material was wet hammer-milled, passed through an ultrasonic disintegrator and homogenized in the manner described in Example 2. The homogenized stem pulp thus produced amounted to 240 pounds at a consistency 2.1% by weight of dry solids.
• Example 2 As in Example 2, 3 parts v(dry weight) of tobacco flour were added to 1 apart (dry weight) of homogenized stem pulp. Glycerol was also added to the extent of 5% by weight of the tobacco flour. In the manner of Example 2, the mixture was cast as a wet coating 0.040 inch thick and dried to a tobacco sheet about 0.006 inch thick.
• Cigarettes made after the manner of Example 2 were judged to be of good smoke taste but to be somewhat stronger in flavor than the cigarette of Example 2.
• EXAMPLE 4 An 8:5 pound batch of Burley stems with 14.2% moisture content, cut to pieces about 2 inches in length, was placed in the extraction vessel of Example 2. Four vacuum extractions were carried out, the last being finished on by a pressure cook for one hour at 20 p.s.i.g. and 259 P. On this occasion the liquor was analyzed to estimate totalalkaloids; the progressive dealkaloidization of the stem may be seen from TableI'I.
• the starting stem contained, on a dry-weight basis, 1.0% of total alkaloids, expressed-as nicotine, that is 0.073 pound.
• the electrical conductivity is expressed as the ratio of that of the liquor to that of a decinormal potassium chloride solution at 77 F.
• Example 2 the residual stem material 'was converted into 224pounds of homogenized pulp with a consistency of 2.15% by Weight cf-dry solids, representing-a yield of 66% by weight of the Burley stems on-a dry solids basis.
• Tobacco flour and glycerol were added to the homogenized stem pulp and the mixture was converted into a tobacco sheet, all as described in Example 2.
• Cigarettes in which the tobacco blend contained 12% by weight of the sheet in shredded form were found to be mild and pleasant and were preferred by some smokers to similar cigarettes containing none of the sheet.
• EXAMPLE 5 A 10 pound batch of Burley stems with 11% moisture content was extracted by following the procedure of Exv ample 2. Approximately 50% of the dry weight of the original stems was removed by extraction.
• the homogenized pulp thus prepared was admixed with 10 pounds of the tobacco flour used in Example 1. Accordingly, only one-third of the total tobacco rejects ad mixed with the extracted Burley stems was homogenized therewith. After adding 0.75 pound of glycerol, the mixture was cast as .a wet coating of 0.050 inch thickness on a conveyor belt of stainless steel and dried to a tobacco sheet of 0.009 to 0.010 inch thickness by condensing steam on the opposite side of the belt.
• Cigarettes made by blending 12% by weight of the resulting tobacco sheet with leaf tobacco were rated by a panel of smoking experts indistinguishable from the cigarettes of Example 1.
• EXAMPLE 6 The midribs of Nigerian flue-cured tobacco were subjected to four vacuum extractions of thirty minutes each, the last extraction being finished ofi by a pressure cook for one hour at 30 p.s.i.g. Data from the four extractions are given in Table III and are based on 10 pounds of stems with 1 8.2% moisture content.
• the homogenized stem pulp thus produced amounted to 152.5 pounds containing 2.5% by weight of dry solids.
• To 46 pounds of this homogenized pulp were added 3.4 pounds of Nigerian flue-cured whole leaf tobacco with 11.2% moisture content in powdered form and 0.15 pound of glycerol.
• the mix-ture was applied on a stainless steel belt as a wet coating of 0.045 inch thickness and dried with the aid of steam condensed on the opposite side of the belt to a tobacco sheet of about 0.009 inch thickness.
• the tobacco sheet had a golden color and pleasing smoke taste.
• Example 7 The extraction and homogenization procedures of Example 6 were carried out with pounds of stems of Jamaican bulk-sweated, flue-cured tobacco with 18 moisture content and yielded 117 pounds of homogenized Y the other case it was Jamaican bulk-sweated, air-cured whole leaf tobacco in pulverized form.
• Each of the two mixtures was spread on a stainless steel belt as a wet coating of 0.050 to 0.055 inch thickness and dried to a tobacco sheet of 0.009 to 0.010 inch thickness. Both tobacco sheets were found satisfactory in the manufacture of cigarettes.
• EXAMPLE 8 A 9 pound batch of stems from Connecticut shadegrown tobacco with moisture content was chopped into pieces of approximately /2 inch in length. These stem pieces were placed in a vessel as described in Example 2. The vessel was sealed and a vacuum of 25 inches of mercury was drawn and held for 30 minutes. Seven gallons of hot water were added to the stems in the vessel and the mixture was boiled under vacuum for half an hour. The liquor was drawn off and replaced with an equal quantity of fresh hot water. The vacuum boil was repeated for an additional half hour. At the end of this period, the vacuum was released, the vessel rescaled and heating continued until a pressure of p.s.i.g. was attained. The batch was held at this pressure for one hour, after which the liquor was drawn oif. The dry weight of the extracted stems was about 60% of the initial dry weight.
• a tobacco flour blend consisting of 4 pounds of ground tobacco dust obtained from cigar filler drying and blending operations, 6 pounds of ground filler tobacco obtained as small cuttings from cigar-making machines, and 3 pounds of ground tobacco dust collected from cigar filler threshing operations.
• dry weights have been determined by drying solids to constant Weight in a dryer maintained at a temperature of 212 F.
• the homogenized stem pulp prepared pursuant to this invention has residual fiber frag ments which are readily seen in a low-power microscope or large field inspection enlarger. While long fiber length has the advantages of increasing both tensile strength and fold resistance of the ultimate tobacco sheet, difliculties from plugging or blocking are encountered in the valvetype homogenizer when the pulp contains long fiber fragments. Also, long fiber length leads to further difficulties when the final mixture is to be spread smoothly and evenly on a supporting surface. For such reasons, residual fiber fragments will in most instances not exceed 0.3 inch in length.
• comminuted stems after being deaerated under vacuum, may be submerged with water and directly cooked at an elevated pressure for a period that will achieve the desired extraction, i.e., at least about 20% by weight of the dry stems, or for a short period that will be supplemented, after replacing the liquor with fresh water, by additional cooking periods carried out at elevated pressure and/ or reduced pressure.
• comminuted stems after being deaerated under vacuum, may be submerged with water and directly cooked at an elevated pressure for a period that will achieve the desired extraction, i.e., at least about 20% by weight of the dry stems, or for a short period that will be supplemented, after replacing the liquor with fresh water, by additional cooking periods carried out at elevated pressure and/ or reduced pressure.
• Patent 2,747,583 shows the drying hoods operating with heated air blown against the coated conveyor belt, where steam is condensed on the bottom side of the belt to dry the coating on the opposite side, the drying hoods operate satisfactorily with blowers drawing ambient air and the moisture evaporated from the coating up through the hoods. Accordingly, the claims should not be interpreted in any restrictive sense other than that imposed by the limitations recited within the claims.
• the improved process of converting tobacco into a coherent form adapted for smoking which comprises extracting a quantity of tobacco stems with water to eliminate extractible components to an extent of at least about 20% by dry weight of said stems, wet-grinding the residual stem material, subjecting the resulting aqueous suspension of said stem material to pressurization and intensive shearing homogenization to yield a highly hydrated pulp having a water retention value of at least about 20, combining a quantity of dry-ground tobacco with said pulp, said quantity of dry-ground tobaccobeing greater on a dry Weight basis than the dry solids in said pulp, and drying the combined pulp and dryground tobacco into said coherent form.
• a tobacco smoking product comprising a major portion by dry weight of dry-ground tobacco and a minor portion by dry weight of tobacco-derived binding agent 11 holding theparticles of-said dry-ground tobacco together as :said smoking iproduct, said binding agent consisting essentially ot an aqueous-extracted tobacco stem residue amounting to not more than 80% by dry weight of the original. tobacco stems subjectedto aqueous extraction,
• stem residue having been pressurized and converted by intensive shearing homogenization to a highly hydrated pulp having a water retention value of at least about 20.
• aqueous binding agent from tobacco stems which comprises subjecting said stems to aqueous extraction to remove therefrom extractible components to the extent of at least about 20% by dry weight of said stems, and effecting pressurization and intensive shearing homogenization of the residual stem material in the presence of water to yield ahighly hydrated pulp of cohesive properties as said aqueous binding agent, said pulp having a aqueous extraction is carried out with boiling water at subatmospheric pressure.
• An improved aqueous binding agent for binding tobacco particles together in a continuous and coherent form which consists of a homogenized aqueous pulp of residual stem material obtained by water extraction of tobacco stems, said residual stem material amounting on a dry basis to from 40% to 80% by weight of said tobacco stems, said homogenized aqueous pulp having a water retention value of at least about 20.
• the binding agent of claim 15 wherein the homogenized aqueous pulp has a consistency of at least about 2% by weight of dry solids.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacture Of Tobacco Products (AREA)

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Cited By (8)

Citations (13)

• 1959
  • 1959-09-17 US US840506A patent/US3043723A/en not_active Expired - Lifetime
• 1960
  • 1960-09-13 DE DE19601517279 patent/DE1517279A1/de active Pending
  • 1960-09-16 DK DK365660AA patent/DK121899B/da unknown
  • 1960-09-16 CH CH1050460A patent/CH450994A/de unknown

Patent Citations (13)

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