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
  • A24B15/18—Treatment of tobacco products or tobacco substitutes
  • A24B15/24—Treatment of tobacco products or tobacco substitutes by extraction; Tobacco extracts

Definitions

• This disclosure relates to a process for the treatment of tobacco. More particularly, the disclosure relates to a process for improving the burning properties of the tobacco, the flavor of the tobacco smoke and the quality of the tobacco ash, by controlling the ion content of the tobacco.
• the process involves the steps of (1) contacting tobacco plant parts with water to obtain an aqueous tobacco extract, (2) treating said extract to adjust its content of certain metallic ions, without removing desirable tobacco constituents and (3) recombining the treated aqueous tobacco extract with the extracted tobacco parts.
• the adjustment of the ion content of the aqueous tobacco extract may be accomplished by contacting the extract With an ion-exchange resin. If desired, other ions may be added to the treated tobacco plant parts to further improve the final tobacco product.
• the burning properties of tobacco and the flavor and the make-up of smoke from tobacco are dependent to a very significant degree on the water-soluble, ionizable materials occurring in the tobacco. These materials have been found to mainly comprise salts of metals.
• the metallic ions which are present in tobacco have been found to control the burning rate and character of the burning of the tobacco.
• the nature of the ash is at least partially dependent on the metallic ions and their proportions, and this in turn affects the combustion.
• the formation of a porous ash results in steady burning, whereas the presence of a low-melting metal salt in excess can cause premature quenching of the burning coal, with attendant formation of acrid and irritating smoke components and of a non-porous coal which obstructs the transmission of air through the tobacco.
• the most prevalent source of premature quenching of tobacco coals has been found to be the presence in the tobacco of a high proportion of low-melting mineral salts, i.e. salts which melt in the 600 to 850 F. temperature range. This premature quenching produces unburned carbon so that the ash is dark or black.
• the low-melting salts are present in amounts that provide excellent combustion and, thus, excellent subjective performance in smoking of the tobacco product can be provided, naturally, by the tobacco.
• the proportion of low-melting salts is so high that a clear porous coal structure is not formed.
• Water washing of tobacco will remove some soluble salts, primarily potassium salts, from the tobacco. However, it is not possible to avoid removing desirable watersoluble constituents by this method.
• the process of the present invention involves the removal of water-soluble ions, exclusively, and, for the purposes of the present invention, it is desirable to leave the pectins undisturbed during the ion adjustment step, since such pectins are structural agents in the tobacco, serving as a glue to bind other constituents.
• Certain polyvalent metallic ions have been removed from tobacco by treatment of slurried ground tobacco with desired salts or acids so that the ions, such as calcium or magnesium, are converted to insoluble salts and are replaced by a monovalent metallic ion or by a hydrogen ion in the treating agent.
• Such treatment has also been found to solubilize the tobacco pectins and to remove them from, or at least relocate them in, the tobacco structure.
• the present invention involves a method whereby metallic ions may be removed from tobacco parts with selectivity and without concurrent solubilization of the tobacco pectins. The ions may then be replaced with other ions, or may be retained in acid form, as desired.
• a process is provided for improving the burning properties of tobacco, the flavor of the tobacco smoke and the quality of the tobacco ash, by controlling the ion content of the tobacco.
• the process involves the steps of (l) contacting tobacco plant parts with water to obtain an aqueous tobacco extract, (2) treating said extract to adjust its content of certain metallic ions, without removing desirable tobacco constituents and (3) recombining the treated aqueous tobacco extract with the extracted tobacco parts.
• the adjustment of the ion content of the aqueous tobacco extract may be accomplished by contacting the extract with an ion-exchange resin. If desired, other ions may be added to the treated tobacco plant parts to further improve the final tobacco product.
• tobacco plant parts are extracted with water and the aqueous extract is then treated with an ion-exchange resin to reduce the amount or eliminate the presence of certain ions from the aqueous tobacco solution.
• the extract is then combined, if desired, with a solution which contains controlled amounts of other ions; and the resulting mixture is recombined with the extracted tobacco parts.
• the aqueous extract may be subjected, as an alternative to an ion-exchange treatment, to treatment by membrane electrodialysis, in order to remove all or. part of certain ions from the solution.
• the potassium ion content of tobacco may be cut down to a low level to eliminate the undesirable burning qualities which result from salts of low melting point.
• Nitrate ion may be removed to give a slower-burning product and to do away with flare-up, or under certain conditions may be increased to provide a faster-burning tobacco.
• Ammonium ion is preferably introduced to tobacco to provide a smooth flavor.
• Phosphate or chloride ion may be added to the tobacco to retard burning. Removal of chloride ion may be accomplished to increase the burning rate of the tobacco.
• the ion content may be altered in such a way that the tobacco has an acid, neutral, or alkaline pH when wet.
• the ions may be exchanged with little or no net effect on the nicotine content, though this is not always possible.
• the product resulting from the proper adjustment of ion content is improved over the original tobacco or a product made from it without adjustment of ion content, in that the burning rate, combustion products, ash-forming quality, appearance and other characteristics of the tobacco can be controlled to a desired extent.
• the present invention provides a method for effectively accomplishing this result. Tobacco treated in this manner has been found to possess improved and controlled burning rate, more desirable combustion products, ash quality and ash appearance.
• One means for accomplishing the selective ion control of this invention after extracting the tobacco parts is to treat the extract with an ion-exchange resin or with more than one such resin in serial treatments.
• the treated extract may then be titrated or otherwise combined with desired additives and recombined with the extracted parts. If the combination is a slurry or paste, it may be formed into a web of reconstituted tobacco by any of the methods which are known in the art, for example it may be formed by casting, roll coating, or papermaking techniques.
• the aqueous extract is contacted with sufiicient ionexchange resin to remove from about 20 to about 95% by weight of the metallic ions, particularly the potassium ions, which are present in the tobacco as low-melting salts (as defined earlier in this specification).
• the contacting may be done at room temperature or at higher or lower temperatures and will generally be conducted for a period of from several minutes to several hours, although shorter or longer times may be employed, depending on the specific form and type of resin employed, the amount of ions to be removed and similar factors.
• Conventional means can be employed to calculate the amount of resin required in the contacting operation. For example, it may be desirable to remove one half of a molecular equivalent of potassium ions and one tenth of a molecular equivalent of calcium ions from ten liters of an aqueous tobacco extract. This would require at least the amount of acid-form ion-exchange resin to correspond to one half plus one tenth or six tenths molecular equivalents of hydrogen ion.
• the ion-exchange resin may be employed in a batch operation or may be a continuous or a semi-continuous operation.
• Semi-continuous operation in a column can be effected by placing pretreated resin in a column of suitable size and passing the reactants through the column continuously.
• the contacting is conducted under continuous conditions. This can be done by packing a column with the ion-exchange resin in particulate form, for example bead form, and passing the aqueous extract through the column.
• the technique employed can be the same as is used in chromatographic columns.
• Cation-exchange resins which may be employed in accordance with the present invention may be strong cation type resins, intermediate cation type resins or weak cation type resins and can, for example, be any of the commercially available cation-exchange resins.
• Satisfactory strong cation-exchange resins include the sulfonic acid types, such as resins formed by cross-linking polystyrene with divinylbenzene and sulfonating the cross-linked product. Such resins are illustrated by the structural formula:
• Amberlite CG SO-type 1 manufactured by Rohm and Haas Co.
• Amberlite CG SO-type 1 manufactured by Rohm and Haas Co.
• carboxylic acid type hydrogen form.
• Another type of weak cation-exchange resin comprehends resins having an -OH group as the ion functional group and formed by reacting polyhydric phenols with formaldehyde. Such resins are illustrated by the structural formula:
• Such resins may be further modified by the addition of one or more additional functional groups.
• the above-shown phenol-formaldehyde resin may be sul- Ionated to introduce sulfonic groups, giving a resin having 6 both SO H and OH groups, as illustrated in the structural formula:
• suitable resins include carbonaceous cation-exchange resins of the sulfonated coal-type. Such resins are commercially obtainable as, for example Zeo-Karb resins. Another type of resin which is suitable is the Zeolite type, either natural or synthetic. These resins are hydrated alkali-aluminum silicates.
• Cation-exchange resins which may be employed in ac cordance with this invention may be strong, weak or intermediate cation-exchange resins of the same types as have been described above.
• Anion-exchange resins which may be employed in accordance with this invention may be strongly basic resins such as the polystyrene quaternary ammonium resins. Satisfactory commercial resins of this type are Amberlite IRA 400, Amberlite IRA 401, Amberlite IRA 410, Dowex 1 and Dowex 2 and can be illustrated by the formula given below:
• Satisfactory weakly basic anion-exchange resins include the primary, secondary, and tertiary amines and are illustrated by such commercially available tertiary amines as Amberlite IR 45, Dowex 3, Amberlite IR 4B, Duolite A2, Duolite A4, Duolite A6 and Duolite A7.
• Duolite A114 which is representative of the weakly basic anion-exchange resins can be represented by the formula:
• aqueous extract of tobacco is subjected to an electrodialyzing potential in a series of cells separated from alternating water cells by means of permeable and semi-permeable membranes.
• the tobacco extract is separated from the Water on the side toward the anode by a neutral membrane, and on the side toward the cathode by a cation-permeable membrane.
• the latter because it will not transmit anions, will not become clogged by the large anions such as those of the polypeptides or the polyphenolics which are found in the extract. Since there are essentially no bulky cations present, similar blockage by cations does not occur.
• the respective anions and cations are often present in the water cells, and are removed as the water is replaced by fresh water and carried away as waste. Alternatively, the water may be recirculated.
• the extract is also replaced by constant flow, but is preferably recirculated to permit more thorough deionization. The removal of ions may approach 90%, or it may be stopped before that amount has been removed by limiting the time of treatment.
• the treated extract may be combined with water-soluble additives including those which contain ions required or desired to be supplemented in the tobacco product. It
• waste solution originally tap water
• the waste solution is pumped through the adjacent compartments in the stack, receiving the inorganic salts removed from the tobacco extract.
• EXAMPLE 1 A 100 g. lot of powdered bright tobacco stems was leached with cold Water. Four hundred thirty milliliters of this extract, at 5% total solids content, was treated for 1 /2 hours with strong anion resin which had a total exchange capacity of 130.0 milliequivalents. The resulting solution had a volume of 500 ml. with a total solids content of 2.9% and was then contacted with 140.0 milliequivalents of strong cation exchange resin for 1% hours. The 550 ml. of liquor recovered :as product from the overall serial contact with both resins had a total solids content of 1.5%. Thus, 32 /2% of the extract solids had been retained by the anion resin, 19% of the extract solids had been retained by the cation resin, and 48 /2% of the extract solids was recovered as a deionized product.
• the ion content of tobacco can be controlled and adjusted to give a predetermined combustion characteristic, smoke flavor and ash color.
• a preferred apparatus for electrodialysis .of tobacco extract has a stack with six operating solution compartments that are 0.063 inch thick, two compartments for isolating the electrode solutions from the tobacco extract solution, and two electrode solution compartments. The width and length of the solution compartments are three inches and twenty-two inches, respectively.
• the cationselective membranes are Ionac MC-3 142 (Ionac Chemical Company, Birmingham, N.J.), and the neutral membranes are A. H. Thomas & Company, 4465A24.9 cellulose dialyzer film.
• the tobacco extract is fed continuously though alternate compartments in the stack, through a conductivity cell (to show the ionic concentration of the solution), a fiowmeter and to a reservoir.
• a pump recycles the tobacco extract through a filter and back to the stack.
• the tobacco extract is recycled through the stack until the desired.
• the cold water leachings from grams of bright stems were treated in 290 milliequivalents of strongly acidic cation exchange resin, Dowex 50 W-X8 from Dow Chemical Company.
• the composition of the soluble effluent from the resin (dry basis) was: K, 0.3%; Ca, 0.15%; total ash, 7.47%; this indicates very complete removal of the most abundant cations.
• Cigarettes were made from deionized liquor as described in Example 3 but with the difference that the deionized slurry was adjusted to pH 5.5 with ammonia prior to formation of the reconstituted sheets. These cigarettes were preferred over the test (acidic) cigarettes described in Example 3.
• EXAMPLE 5 Separate cold water leachings from several 100 g. portions of bright stems were treated with 290 milliequivalents of acid cation-exchange resin, Dowex WX8 from Dow Chemical Company. The treated solutions were recombined with the bright stern pulp, and cooked for 25 minutes at 18 lb. pressure. The slurries were refined by Waring blendor and treated as follows:
• Sheets were cast from the four slurries and the dried sheets were shredded and converted into cigarettes. These cigarettes were smoked by a small panel with the following result:
• Cigarette A (containing ammonium ions) was considered to produce the best tasting and mildest smoke.
• Cigarette C (mostly calcium) produced a fairly mild smoke but had a somewhat unusual taste.
• Cigarette B (calcium plus potassium) was most similar to the control, producing a harsh smoke with a characteristic stemmy taste.
• Tobacco extract was prepared by soaking 20 lb. of bright stems overnight in 50 lb. of water and expressing approximately 25 lb. of the extract from the soaked stems.
• One gallon of the extract was introduced into the tobacco extract reservoir of a membrane electrodialysis apparatus. Tap water was introduced into the waste reservoir. The water and extract were circulated through the compartment. The voltage applied to the electrodes was adjusted to give a current flow of about 10 8.5 amp, or a current density of millamp/sq. cm. of membrane.
• the two solutions were circulated through the stack for approximately five hours, so that about 85% of the ions was removed, according to conductivity 5 measurement. Analysis of the stem extract before and after demineralization is compared in Table III.
• a method for treating tobacco which comprises the steps of:
• step (3) recombining the deionized product of step (2) with the insoluble tobacco portion of step (1).

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacture Of Tobacco Products (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (1)

Publications (1)

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Cited By (35)

Families Citing this family (4)

• 1968
  • 1968-10-28 US US771268A patent/US3616801A/en not_active Expired - Lifetime
• 1969
  • 1969-09-25 GB GB47367/69A patent/GB1279500A/en not_active Expired
  • 1969-09-30 CH CH1472269A patent/CH531840A/de not_active IP Right Cessation
  • 1969-09-30 DE DE1949338A patent/DE1949338C3/de not_active Expired
  • 1969-09-30 FR FR6933303A patent/FR2021677A1/fr not_active Withdrawn
  • 1969-09-30 NL NL6914770A patent/NL6914770A/xx unknown

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