Preparation Of Reconstituted Tobacco

Abstract

Tobacco parts are treated with ammonium salts of organic acids, added or formed in situ, in the presence of ammonium hydroxide to obtain an alkaline pH, to release tobacco pectins and form calcium and/or magnesium salts with the organic anions. The pectins act as a binding agent and together with the treated tobacco and precipitated salts constitute a mix that may be cast or otherwise treated to form a reconstituted tobacco product.

Description

BACKGROUND OF THE DISCLOSURE

The preparation of reconstituted tobacco or tobacco material generally produced in sheet form makes use of waste or scrap tobacco parts or dust normally bound together by providing an adhesive to give the product coherence. Various adhesives or binding agents have been used or proposed for this purpose, many of them being cellulose or other non-tobacco derivatives. Improvements in binding agents have led to the use of adhesive material derived from tobacco, notably tobacco pectins. These substances, and methods for utilizing them, are described in U.S. Pat. Nos. 3,353,541; 3,409,026; 3,499,454 and others. The patents describe the release of pectins and pectinic substances from the tobacco parts for subsequent redeposit on the same or other tobacco parts as adhesives to bind them into a coherent sheet or other form. The pectin release is carried out by the use of special agents which act by removing the divalent metal cross-links, essentially calcium and magnesium by a number of methods, for example, a method utilizing additive substances which remove the divalent metal ions by forming relatively insoluble salts; a method which removes the ions by an additive causing a chelating or sequestering action; or by another method which acidifies the system with an acid and produces soluble salts of Ca and Mg, which can be washed out, leaving the pectins in the insoluble acid form, but which then requires an alkalinizing step to solubilize the pectins. These methods made possible the separation of the pectins from the insoluble portions of tobacco, generally without separation of the released pectins, leaving these and other components of the pectin-releasing step combined in the aqueous slurry which is then cast into a final reconstituted tobacco product.

As a consequence of such prior methods, ash-forming agents that are added or formed from such additives usually remain in the product. These retained additives, left in the tobacco, may affect the flavor, ash color, and other properties of the product. Such ash-forming ingredients, moreover, may increase the delivery of total particulate matter (TPM) in the smoke. The present invention is an improvement in the production of a reconstituted tobacco in that the release of tobacco pectins in situ may be accomplished without the addition of ash-forming inorganic salts or acids, while at the same time, enhancing the flavor and aroma of the smoke.

SUMMARY OF THE INVENTION

According to the present invention, selected monobasic organic acids of six to 18 carbon atoms or polybasic acids of two to 12 carbon atoms and ammonium hydroxide or ammonium salts of such acids, are added to tobacco parts as cross-links destroying agents. The latter additives or components thereof, are volatilized in subsequent drying operations, or are burned in smoking to produce principally the same products that arise from combustion of tobacco without additives, namely, carbon dioxide, water, ammonia, and the like, so that ash appearance and, more importantly, TPM delivery are substantially unchanged. Smoking of the products has shown the flavor to be acceptable, and sometimes enhanced and novel, mild rather than harsh, with no undesirable foreign notes. The sheet produced is pliable and plastic, and added plasticizer (e.g., triethylene glycol) may be reduced or eliminated.

DESCRIPTION OF THE INVENTION

The process comprises the treatment of the tobacco parts, preferably in finely divided form, with an aqueous solution or suspension of selected organic acids with ammonium hydroxide or the ammonium salt of one or more of these acids, in the presence of excess ammonium hydroxide.

The treatment of the tobacco in the presence of these ammonium salts and ammonium hydroxide results in the release of the pectinaceous components from the tobacco in the form of ammonium pectates. The original pectinaceous components, with may be termed protopectins, consist essentially of calcium and/or magnesium salts of polygalacturonic acid, the divalent metallic atoms acting as cross-links between the galacturonic chains, these being destroyed in the reaction.

When the pectins are released as ammonium pectates, the calcium and/or magnesium cations form substantially water-insoluble salts with the anionic groups, particularly when the pH is in the alkaline range. These insoluble salts, together with the ammonium pectates acting as binding agents, are combined with the treated tobacco and are extruded, cast or otherwise formed into a reconstituted tobacco product which may then be processed in known manner to produce the desired form of smoking product.

The organic acids that are selected are unsubstituted aliphatic or aromatic mono or polycarboxylic acids or such acids having only hydroxy and lower alkoxy groups as substituents. In other words, the acids should consist only of carbon, hydrogen and oxygen. Meeting these qualifications, the monocarboxylic acids preferred are fatty acids having six to 18 carbon atoms while the preferred polycarboxylic acids are those having two to 12 carbon atoms.

These acids should have the general characteristic of forming calcium or magnesium salts that, under the conditions of treatment, particularly in an alkaline environment well above pH 8, preferably pH 9 to 10, are substantially insoluble in the aqueous medium. As a component of the final tobacco product, these salts either volatilize off, or alternatively, break down during the combustion of the tobacco to calcium or magnesium carbonates, carbon dioxide, water and, in fact, the same elements normally released when untreated tobacco is burned. Since there are ammonium components also present, either as ammonium pectates or substantially trace amounts of free ammonia or ammonium hydroxide, ammonia gas is volatilized out either before the product is smoked, that is during the drying step, or certainly during the combustion. The end result is that the combustion of the treated tobacco produces the same type of ash as would be produced from the combusion of tobacco that had not been treated and was free of additives.

In addition to the important effect of the ammonium salts and excess ammonia in releasing tobacco pectins, as an added feature of the invention, when organic acids are selected, or when ammonium salts of the acids are selected, it is within the scope of the invention to select such acids or salts as described above but capable of providing a special flavor and aroma in addition to releasing pectins and leaving unchanged the ash color or other desired properties of the product. Thus, citric, malic or vanillic acids or other flavor or aroma inducing acids with ammonium hydroxide, or alternatively their ammonium salts, with excess ammonia, when used for the release of pectins and water-insoluble salts, will also produce an exceptionally flavorful smoke.

With respect to the longer-chain fatty acids, either saturated or unsaturated, for example, stearic, oleic, linoleic or linolenic acids or their ammonium salts, these provide not only a subtle flavor characteristic of the smoke when used in the desired concentration, but also possess a plasticizing effect that requires little or no added plasticizers normally used in making a reconstituted tobacco product. Thus, one may select the acid or salt tobacco treating agent which, under the conditions of operation, will act merely to release pectins as adhesive or binding agents but whose ash-forming salts will not change the flavor, ash color or other properties of the product, or achieve the same results with the additional feature of producing a softer, more plastic sheet, or again achieve the same results but have an additional flavoring component.

The preferred acids that may be used in carrying out the process of the invention are citric, malic, gluconic, oxalic, tartaric, mellitic, vanillic, sebacic, lauric, stearic, oleic, linoleic or linolenic acids. Particularly preferred acids are citric or malic acids. As indicated previously, one may use a single acid or a mixture of different acids.

Describing the invention in greater detail, tobacco plant parts, usually waste or scrap tobacco parts in the form of flakes, shreds, tobacco fines or dust, but preferably in finely divided form, is slurried with an aqueous solution of an ammonium salt of a selected organic acid or a mixture of such salts. The amount of added salt may be in the range of about 0.0 to about 0.25 mols of salt per 100 grams of tobacco, but preferably in an amount of about 0.025 to 0.08 mols per 100 grams of tobacco. Additionally, sufficient ammonium hydroxide must be added to reach an alkaline pH, preferably from pH 9 to about pH 10.

During the reaction of pectin release and salt formation, the slurry is maintained at a temperature of from about 25.degree. to 110.degree.C. for about one-half to 24 hours. Heating may not be necessary since heat may be generated by the reaction taking place in the treating vessel. While heating or cooking is being carried out, more ammonia may be needed to maintain the alkaline pH. After sufficient time has elapsed and when the reaction is substantially completed, the tobacco slurry may be refined by use of a rapid or high speed beater, followed by deaeration before casting, spraying, roller-coating or the like in reconstituted tobacco forms such as webs, sheets, fibers or other desired forms.

Instead of using ammonium salts as such, one may form these salts in situ or at least have the desired anions and cations present by using one or more organic acids and sufficient ammonium hydroxide, usually in excess so as to result in an alkaline pH of pH 9 or higher. In this case, one may add the same amount of acid as indicated for the salt, namely, from about 0.0 to 0.25 mols of acid for each 100 grams of tobacco with a more preferred range of 0.025 to 0.08 mols per 100 grams of tobacco. Sufficient ammonium hydroxide is then added to result in the slurry achieving an alkaline pH in the range of 9 to 10.

As an alternative to the use of added ammonium salts, or the use of an added organic acid with ammonium hydroxide, it is possible under certain circumstances to use the citric, malic, oxalic or tartaric acid content of tobaccos containing these acids or salts of these acids in sufficiently high concentration so that it would not be necessary to add such acids to the tobacco slurry. In that case, it would only be necessary to add sufficient ammonium hydroxide to bring the pH of the aqueous tobacco slurry to pH 9 to 10 and heating, following the same treatment as previously described. Thus, ammonium pectins would be formed from the released pectins and the calcium and magnesium cross-linking cations of the tobacco protopectins would form salts with the acidic anions.

Subsequent to the release of the pectins, the entire reaction mix may then be cast, extruded, sprayed or otherwise treated to solidify the solids by procedures well known in the art, to form a reconstituted tobacco product.

The following examples are illustrative.

Example 1

A slurry was prepared in a Waring blender from 50 g of tobacco dust (-50 mesh), 450 ml. of water, 1.0 g of citric acid, and sufficient aqueous ammonia to raise the pH to 9.5. The slurry was refined by beating for 30 minutes, at which time the temperature had reached 90.degree. C. The viscosity had reached a maximum after five minutes. No additional heat was applied. The slurry was deaerated under vacuum on a steam bath (pH after cooling, 8.8). The hot slurry was cast on steel plates by using a casting knife set at 50 mils, dried over a steam bath, and stripped from the plates. A uniform, dense sheet without pinholes resulted. Its properties were:

Weight - 14.9 g/sq. ft.

Wet tension coefficient - 1.74 g/in/g/sq. ft.

pH (sheet reslurried in 10 parts water) 5.4

Example 2

Portions of tobacco dust (-50 mesh) and water, 50 g and 450 ml. respectively, were treated with additives and conditions as listed in Table I, using a Waring blender for refining and a steam bath for heating. Deaeration after refining was for 10 minutes except the last run where 1 hr. heating took its place. Casting on steel plates with a casting knife set at 50 mils, and drying produced sheets with the properties listed in Table I.

Example 3

Tobacco dust (50 g, -50 mesh) and citric acid (7.5 g) were slurried with 285 ml. water in a Waring blender. To the slurry concentrated NH.sub.4 OH was added to pH 9.0 which was maintained during the heating period. The slurry was heated to 95.degree. C in a steam bath for 2 hours, and refined for 1 minute. The hot slurry was cast on steel plates using a casting knife set at 35 mils, dried over a steam bath and doctored off. pH of the cold slurry was 8.7, sheet pH was 5.3. The sheet was satisfactory but it did have many fine cracks.

Example 4

A slurry consisting of 1,019.4 lb. water, 174.8 lb. tobacco dust, 24.6 lb. citric acid, and 42 lb. of 30% NH.sub.4 OH was prepared in a mixing tank. The temperature was maintained ##SPC1## at 67.degree. C, and the pH at 9.0. The slurry was passed through a refiner three times and constantly recirculated for approximately 4 hours. The temperature of the slurry at the cast box was maintained at 57.degree. C. Casting was done on a steel belt; pH of the cold slurry was 9.2. A uniform, dense sheet resulted.

pH -- 5.4

Pendulum tensile -- 0.65 kg/in

Weight -- 14.4 g/sq. ft.

Water -- 12.9 percent

Folded tensile -- 0.32 kg/in

Wet tensile -- 10.1 g/in

Wet tensile coefficient -- 0.72 g/in/g/sq. ft.

Instron tensile -- 0.50 g/in/g/sq. ft.

Elongation -- 2.3 percent

Work to break -- 18.8 g-cm/sq. in.

The sheets were cut into filler and cigarettes were prepared for smoke test comparison against a standard cigarette, as shown in Table II below. For the smoke tests, 15 mm. filter tips were attached to the cigarettes, and then 50 mm. of cigarettes smoked for TPM and nicotine.

TABLE II

Cigarette with Control, Stand- Rod: Citric Acid Filler ard Cigarette Length mm. 60 60 Circumference mm. 25.2 25.2 Weight g/cigt 1.38 1.13 RTD*, in. water 0.7 1.0 Filler rod TPM, mg/cigt 35.3 40.8 Filler rod nicotine, mg/cigt 1.3 1.4 Puff count 14.2 11.2 TPM/puff mg. 2.49 3.64 Tobacco smoked, g 1.16 0.94 Per gram of product smoked: TPM mg 30.5 43.4 Puff count 12.5 11.9 *Resistance to draw.

This lower delivery in comparison with conventional filler is preferable to a higher delivery.

Example 5

Sebacic acid (5 g), 50 g tobacco dust (-50 mesh), and 450 ml. H.sub.2 O were slurried in a Waring blender. Concentrated NH.sub.4 OH was added to raise pH to 9.5. The slurry was refined for 30 minutes during which period the temperature was raised to 90.degree. C. After the refining, the slurry was heated on a steam bath in order to deaerate. It was then cast on stainless steel plates using a casting knife with 50 mils setting. To dry the product the plates were placed over a steam bath. The sheets were doctored.

Sheet weight - 14.9 g/sq. ft.

Wet tensile coefficient - 4.99 g/in/g/sq. ft.

Example 6

Mellitic acid (5 g), 50 g tobacco dust (-50 mesh), and 450 ml. H.sub.2 O were slurried in a Waring blender. Concentrated NH.sub.4 OH was added to adjust pH to 9.5. The slurry was heated oon a steam bath for one hour, then refined for 10 minutes, and finally heated for another hour. The slurry was then cast on stainless steel plates using a casting knife with setting at 50 mils. The sheets were dried over a steam bath and doctored.

Sheet weight - 12.70 g/sq. ft.

Wet tensile coefficient - 13.39 g/in/g/sq. ft.

Example 7

Ten grams oleic acid, 50 g tobacco dust, and 450 ml. H.sub.2 O were slurried in a Waring blender. pH was adjusted to 9.0 with concentrated NH.sub.4 OH. The slurry was heated at 90.degree. C. over a steam bath for 1 hour, refined for 5 minutes, and again heated for an hour. The slurry was cast on stainless steel plates using a casting knife set at 50 mils, dried over a steam bath and doctored. The product was soft and plastic.

Sheet weight - 13.39 g/sq. ft.

Wet tensile coefficient - 7.84 g/in/g/sq. ft.

Ammonium oleate (10.6 g) may be used in place of the oleic acid in the above example, and using sufficient ammonium hydroxide to obtain a pH of 9. The heating, refining and casting are described above. The product is the equivalent of that given in the example.

Example 8

Vanillic acid (8.4 g), 50 g tobacco dust and 450 ml. H.sub.2 O were slurried in a Waring blender. pH was adjusted to 9.3 with concentrated NH.sub.4 OH. The slurry was heated for 2 hours at 90.degree. C. in a steam bath, refined for 10 minutes, and deaerated for 15 minutes. The slurry was cast on stainless steel plates using a casting knife set at 50 mils, dried over a steam bath and doctored. The product had a subtle sweet aroma. Cigarettes prepared from this product when smoked had a subtle vanilla flavor both in the main and side streams.

Sheet weight - 15.0 g/sq. ft.

Wet tensile coefficient - 1.47 g/in/g/sq. ft.

pH of product - 5.3

Example 9

Ammonium sebacate (6 g) and 50 g (-50 mesh) of tobacco dust were slurried in 450 ml. H.sub.2 O in a Waring blender. The pH was adjusted to pH 9.0 with concentrated NH.sub.4 OH. The slurry was brought to 90.degree. C. and held at that temperature for 1 hour. It was refined for 30 minutes and then heated on a steam bath to deaerate for about 30 minutes. The slurry was cast on stainless steel plates using a casting knife set at 50 mils, then dried over a steam bath and doctored. The product had similar characteristics to the product of Example 5.

Example 10

Eighty pounds of tobacco dust having a pH of 5.7, 12 lb. 8 oz. concentrated NH.sub.4 OH, and 454 lb. H.sub.2 O were placed in a vat with steam coils and circulating pump. The slurry was heated to about 90.degree. C. for one hour while being constantly circulated during the heating. The slurry was recycled through refiners for about 45 minutes. The temperature was maintained at about 90.degree. C. and additional NH.sub.4 OH was added to maintain pH at 9.0. When refining was completed the total solids were 17 percent and the viscosity approximately 8,000 centipoises at 21/2 RPM, spindle D, using Brookfield wire T-form spindle. A portion of the slurry after deaeration was hand cast on stainless steel plates at 50 mils, using a casting knife.

Hand Cast Product:

Sheet weight - 20.32 g/sq. ft.

Wet tensile coefficient - 1.28 g/in/g/sq. ft.

Claims

The invention claimed is:

1. The method of forming a tobacco smoking product which comprises,

a. combining water, tobacco and a reagent selected from the group consisting of

1. ammonium salts of carboxylic acids and

2. ammonium hydroxide and a carboxylic acid

wherein the carboxylic acid is selected from the group of monobasic fatty acids of six to 18 carbon atoms, polybasic acids of two to 12 carbon atoms and mixtures thereof,

b. adding sufficient ammonium hydroxide to bring said slurry to a pH of 9 to 10,

c. releasing the tobacco pectins and forming insoluble calcium and magnesium carboxylates by holding said slurry at a temperature of about 25.degree. to 110.degree. C. for about one-half to 24 hours while maintaining said pH at 9 to 10 through the addition of ammonia, and

d. drying the components of said slurry to form a homogeneous tobacco smoking product.

2. The method of claim 1, wherein the tobacco of step (a) is in finely divided form.

3. The method of claim 1, wherein said reagent comprises a polycarboxylic acid of two to 12 carbon atoms and ammonium hydroxide.

4. The method of claim 1, wherein said reagent comprises a monocarboxylic fatty acid having six to 18 carbon atom and ammonium hydroxide.

5. The method of claim 1, wherein said reagent comprises ammonium salts of said mono and polycarboxylic acids.

6. The method of claim 1, wherein the reaction is carried out in the presence of ammonium cations and organic acid anions derived from acids of the group consisting of oxalic, citric, malic, sebacic, tartaric, mellitic, vanillic, gluconic, stearic, lauric, oleic, linoleic and linolenic acids.

7. The method of claim 3, wherein the carboxylic acid is citric acid.

8. The method of claim 4, wherein the carboxylic acid is oleic acid.

9. The method of claim 5, wherein the salt is ammonium citrate.

10. The product produced by the process of claim 1.