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Smoking mixtures A smoking mixture comprising a tobacco-substitute in admixture with extract material obtained by treating Nicotiana Rustica with a nicotine-dissolving solvent.
Primary Examiner: Rein; Melvin D. Attorney, Agent or Firm: We claim: 1. A smoking mixture comprising a mixture of a tobacco substitute with from 1 to 11 percent of its weight of extracted material obtained by treating Nicotiana Rustica with a nicotine-dissolving solvent and removing the solvent so that the extracted material is wholly free from any toxic solvent that may be used for said extraction, said mixture being blended with from 65 to 90 percent of its weight of tobacco and said tobacco substitute comprising a thermally degraded carbohydrate prepared by subjecting carbohydrate to a catalyzed degradation at about 100.degree.C until the weight of degraded carbohydrate is less than 90 percent of the weight of the orignal carbohydrate. 2. A smoking mixture according to claim 1 wherein the tobacco substitute comprises cellulose, a cellulose ether, oxidised cellulose or lettuce leaves. 3. A smoking mixture according to claim 1 wherein the tobacco substitute comprises a thermally degraded cellulose. 4. A smoking mixture according to claim 1 wherein the extract material is obtained by treating Nicotiana Rustica with a lower aliphatic alcohol having a boiling point up to 120.degree.C. 5. A smoking mixture according to claim 1 fabricated in sheet form containing a film-forming agent. 6. A smoking mixture according to claim 1 incorporating tobacco. 7. A smoking composition according to claim 1 wherein the tobacco substitute is in admixture with from 4 to 9 percent of its weight of the extract material. This invention relates to smoking mixtures. In view of the widely held opinion that the smoking of tobacco, especially in cigarette form, can cause lung cancer and bronchitic ailments, attention is turning to the provision, as tobacco substitutes, of smoke-producing substrates which produce less tar and other harmful substances than tobacco, for example to cellulose, oxidised cellulose and particularly to heat-treated cellulose prepared for example by the process described and claimed in United Kingdom Pat. No. 1,113,979. Unfortunately the smoke from such tobacco substitutes lacks the flavour of tobacco and in order to provide a palatably acceptable smoke it is necessary either to mix the substitute with tobacco or to discover suitable flavouring material for addition to it. Mixtures with tobacco produce smoke with a health hazard proportional to the tobacco content. If desired, tobacco substitutes can be mixed with the dried and cured leaves from the plant genus Nicotiana Rustica. This genus contains very high proportions of nicotine, for example up to 14 percent by weight and unlike Nicotiana Tobaccum it has not proved generally acceptable as the basis of smoking materials owing to the extremely strong and unpalatable flavour of its smoke. Small proportions may be tolerated however in admixture with tobacco substitutes which themselves produce a neutral smoke and in this way it may be possible to produce mixtures with less health hazard than palatably similar mixtures containing tobacco. It is desirable, however, to reduce the health hazard from smoking as far as possible and for this reason the amount of tobacco or other nicotine-containing plant genus in smoking mixtures should be minimised or reduced to zero if possible. According to the invention a smoking mixture comprises a tobacco-substitute in admixture with extract material obtained by treating Nicotiana Rustica with a nicotine-dissolving solvent. The expression 'tobacco substitute' means any solid substance which, though not of tobacco origin can be smoked in the same way as tobacco. Tobacco substitutes may be for example of carbohydrate origin, e.g., those described in British Pat. Nos. 1,055,473 and 1,143,500 and U.S. Pat. No. 3,106,209 namely cellulose, oxidised cellulose and lettuce leaves. Cellulose ethers may also be used. Advantageously the tobacco-substitute may be a thermally degraded carbohydrate, made for example by subjecting carbohydrate (particularly cellulose) to a catalysed degradation process at above 100.degree. (e.g., 100.degree. to 250.degree.C as in our UK Pat. No. 1,113,979) until the weight of degraded carbohydrate is less than 90 percent of the weight of the original carbohydrate. A similar substance is obtainable as described in our British Pat. No. 1,289,354 by acid or base catalysed condensation of a compound of the formula R.sup.1 COCH.sub.2 CH.sub.2 COR.sup.2 (I) wherein R.sup.1 and R.sup.2, which may be the same or different, each represents a hydrogen atom or an alkyl, hydroxyalkyl, or formyl group or a precursor of such compound (I). Nicotine-dissolving solvents which may be used for extracting the Nicotiana Rustica are more particularly lower aliphatic alcohols having boiling points up to 120.degree.C. Specific examples are methanol, ethanol, n-propanol, isopropanol, n-butanol, iso-butanol and t-butanol. The extraction may be carried out by known techniques, for example by the use of apparatus of the Soxhlet type, but it is preferable to employ a hot extraction technique, for example, by filling a permeable bag with dried and crushed Nicotiana Rustica, suspending this in vapour from boiling solvent and allowing condensed solvent from a reflux condenser to pass into and downwardly tnrough the bag and its contents. The amount of extract material in the smoking mixtures of the invention may be, for example from 1 to 25 percent by weight of the amount of the tobacco substitute, but for best flavour effect the preferred amount is from 4 to 9 percent. Smoking mixtures of the invention may be made by mixing of the tobacco substitute and the extract material in any convenient manner. Other known ingredients of smoking mixtures may be included to impart desired physical properties and burning characteristics. For example the smoking mixtures may incorporate glow-controlling catalysts, materials to improve ash coherence and colour, nicotine, other flavourants, medicaments, humectants or film-forming agents. If desired tobacco may also be incorporated. Preferably however the smoking mixtures of the invention are fabricated in sheet form, containing a film forming agent, for example a natural gum or pectin or a cellulose ether, especially carboxymethyl cellulose or a salt thereof. To prepare such sheets the ingredients of the mixture preferably with the tobacco substitute in a finely divided form, may be mixed with a sufficient quantity of water to produce a slurry which is then cast on to a surface and dried. It may be convenient to include in such a slurry a portion of the solution directly obtained by treating Nicotiana Rustica with a solvent. If desired however the solvent may be wholly or partially recovered and replaced by water to form a solution/suspension which can be incorporated with the slurry. Better results in the film-forming operation are sometimes obtained this way, and a potential fire hazard is removed. Sheet material produced from the slurry may be shredded to provide material in a form suitable for smoking. When tobacco is incorporated in the smoking mixture it may be as comminuted tobacco, which may be incorporated in the slurry before casting. Alternatively tobacco shred may be blended with the shredded sheet. Quite surprisingly it is found that despite the unacceptable taste of the smoke from Nicotiana Rustica itself the smoking mixtures of the invention give palatably acceptable smokes and are generally preferred by smokers to comparable mixtures which do not contain any of the extract material obtained by treating Nicotiana Rustica with a nicotine-dissolving solvent. Certain mixtures of tobacco-substitutes with the extract material may, however, produce smokes with undesirable off-notes. By blending such mixtures with tobacco these off-notes may be masked. A preferred smoking mixture comprises a mixture of a tobacco substitute with from 1 to 11 percent (especially 4 to 9 percent) of its weight of extract material obtained by treating Nicotinia Rustica with a nicotine-dissolving solvent, said mixture being blended with from 65 to 90 percent of its weight of tobacco, particularly flue-cured Virginia tobacco. Off-notes in the smoke produced by the smoking mixtures of the invention arise because the extract material does not contain an ideal balance of nicotine and flavourants. It is a further feature of the invention to separate from extract material fractions containing respectively most of the nicotine and most of the flavourants and to combine the said fractions with tobacco substitute in such proportions as to provide a product with acceptable smoke flavour. To separate the said fractions a solution of the extract material, preferably in an alcoholic solvent, may be contacted with a sorbent solid to absorb thereupon most of the nicotine, and thereafter nicotine may be recovered from the said solid and flavourants from the liquid phase. The extract may be contacted with sorbent solid by mixing followed by filtration, or by allowing it to flow through a packed column of the solid already moistened with liquid in the technique already familiar in the fields of chromatography or ion-exchange. Specific solids which may be used are absorbent solids which, when mixed with water to form a 1 percent suspension, give a liquor of pH 2.5 to 6.5. More particularly acid clays and cation exchange resins are of value. Specific examples of acid clays which may be used are activated bentonites and montmorillonites. Fulmont 300C, an activated acid clay is of especial value. This substance, when mixed with water to form a 1 percent suspension, gives a liquor of pH 6.4. Specific examples of cation exchange resins which may be used are those commercially available under the names Zeo-carb K225 (H) and Amberlite IRC 50H. In a preferred method of working, the treatment with sorbent solid is carried out so as to leave at least 50 percent by weight of the extracted material in the solution. The amount of solid and the time and temperature of the treatment necessary to achieve this will of course depend upon the particular solid chosen, and the type of treatment used, i.e., whether the extract is stirred with the solid or allowed to flow through a column of solid. The resultant flavourant-rich material in the solution may be used directly to flavour tobacco substitutes to produce smokes which are substantially without the harsh off-notes produced by flavouring in similar manner with the untreated extract material from Nicotiana Rustica according to particular commerical requirements or even individual tastes. Other flavour producing ingredients may be present as desired, including tobacco. Nicotine and other basic material absorbed by the solid can be recovered from it by known techniques, for example by elution with a solvent (sometimes a more powerful solvent than that present in the original extract) or by steam distillation from the solid after basification e.g. with sodium hydroxide. Nicotine-rich material recovered in this way may be used to fortify tobacco or tobacco substitutes and if desired may be incorporated therewith together with flavourants or flavourant-rich material also obtained from Nicotiana Rustica in the above described manner. It is especially advantageous to use as the tobacco substitutes those which are more particularly described in our UK Patent Applications Nos. 1,299,296 -- tobacco substitutes of acceptable burning rates containing large amounts of filler 13862/70 -- tobacco substitute containing protein 13861/70 -- tobacco substitutes containing protein and isoprenoid 13865/70 -- tobacco substitute containing protein and phenylethylalcohol or phenylacetic acid. The invention is further illustrated by the following Examples in which all parts and percentages are by weight. Flavour assessments of cigarettes recorded in the Examples were carried out by one of the following procedures, each of which required a group (panel) of people to smoke and comment on the cigarettes. The first procedure used a group of smokers especially selected for their high consistent flavour sensitivity and long experience in testing the flavour of tobacco cigarettes. This group, called the Expert Panel, consisted of a small number of the order of 3-6 people. The second procedure required a much larger number of panel assessments (minimum number 22; minimum panel size 11) and measured a preference for one cigarette against another. The method was devised on a statistical basis such that the certainty that a preference existed could be stated as a percentage confidence. This panel was called the Statistical Preference Panel. EXAMPLE 1 2.8 parts of glycerol, 0.8 parts of citric acid and 1 part of potassium citrate were dissolved in 20 parts distilled water and the resultant solution added to a stirred solution of 2 parts of sodium carboxymethyl cellulose in 80 parts hot distilled water. To this solution was added 9 parts of a material made by heating .alpha.-cellulose impregnated with ammonium sulphamate for 4 hours at 200.degree.C and to which had been added 0.74 parts of casein (fat free), 2 parts of calcium carbonate and 20 parts of a concentrated solution obtained by Soxhlet extracting Nicotiana Rustica with ethanol and containing 1.68 parts of extract material. The resulting slurry was stirred till homogeneous (approximately 1 hour). The slurry was cast on glass plates to give a film of 48-52 grams/square metre basis weight and shredded. The cigarettes made from this shred were smoked by an expert panel of four smokers who were unanimously of the opinion that a cigarette tobacco flavour was present, whereas this was found to be absent from cigarettes of similar composition but with the exclusion of the Nicotiana Rustica extract. However, some off-notes characteristic of Nicotiana Rustica but foreign to flue-cured tobacco were detected. EXAMPLE 2 1.1 parts of glycerol were dissolved in 20 parts distilled water and this solution added to 1.6 parts of sodium carboxymethyl cellulose in 80 parts of distilled water and the mixture stirred. 6.9 parts of magnesium carbonate (magnesite), 4.1 parts of calcium carbonate, 0.2 parts of casein (fat free), 5.1 parts of a material prepared by heating .alpha.-cellulose in the presence of ammonium sulphamate and 1.0 parts of extract material obtained by Soxhlet extracting Nicotiana Rustica with ethanol, this material being redissolved in 20 parts of ethanol. The resultant slurry was stirred for at least one hour then cast on glass plates to give a film which on drying removed the ethanol by evaporation and gave a sheet of basis weight 48-52 grams/square metre. The sheet was shredded and made up into a blend containing 40 parts of this shred and 60 parts of flue-cured Virginian tobacco. Cigarettes from this blend were compared with those of a 40:60 tobacco blend from shred containing no extract material but otherwise identical. The cigarettes were compared using a statistical preference panel test and the panel stated a preference for the cigarettes containing the Rustica tobacco extract, with 78 percent confidence. EXAMPLE 3 1.6 parts of glycerol and 0.4 parts ammonium sulphate were dissolved in 20 parts of distilled water and this solution was added to a mixture of 70 parts of distilled water, 5.3 parts of magnesite, 0.9 parts of bentonite, 3.0 parts of calcium carbonate, 1.7 parts of extract material obtained by treating Nicotiana Rustica with ethanol, this material being mainly in solution but partly in suspension in 10 parts of distilled water. This mixture was stirred and to it was added 2.2 parts of sodium carboxymethyl cellulose and 4.9 parts of a material prepared by heating .alpha.-cellulose in the presence of ammonium sulphamate. Stirring was continued for at least one hour. The resulting slurry was cast on glass plates to give a film which, on drying, had a basis weight of 48-52 grams/square metre. The sheet was shredded and made up into a blend containing 50 parts of this shred and 50 parts of flue-cured Virginian tobacco. Cigarettes from this blend were compared with those of a 50:50 tobacco blend from shred containing no extract material but otherwise identical. The cigarettes were compared using a statistical preference panel test and the panel stated a preference for the cigarettes containing the Rustica tobacco extract with 96 percent confidence. EXAMPLE 4 Sheet material was prepared identical with that described in Example 3 except that 2.5 parts of the extract material was used instead of 1.7 parts and the amounts of the other ingredients were scaled down proportionately. A similar panel assessment of cigarettes from 50:50 tobacco blends in this case showed that the preference for the extract-containing cigarette had been destroyed by increasing the amount of this extract. EXAMPLE 5 Dried ball-milled Nicotiana Rustica (1,000 g) of moisture content 7.9 percent extracted in a Soxhlet apparatus with ethanol (3,000 ml) for 32 hours. Analysis of an aliquot portion of extract showed that all the nicotine had been extracted and 36.3 percent of the dry weight of the Nicotiana Rustica had passed into solution. Treatment of the above ethanol extract by stirring at room temperature with Fulmont 300C, and subsequent filtration of the mixture gave filtrates which contained 4-11% of the original nicotine of the extract and 31-40 percent of the total original solids, according to the conditions used. Taste assessment of one such filtrate which contained 11% of the original nicotine and 38 percent of the total original solids was carried out by using it in place of the total extract in a smoking mixture prepared as described in Example 1. At 10 percent concentration of solids this gave a smoke with no off-notes and which had a good flue-cured tobacco flavour. A similar flue-cured tobacco flavour was produced at 4.7 percent concentration of solids. At 2.5 percent concentration of solids a small but definite flue-cured tobacco flavour was observed but the effect was inferior to that produced at 4.7 percent concentration. All nicotine retained on the solid residue after filtration, was recovered by steam distilling a slurry of the solid in 30 percent w/w aqueous sodium hydroxide at 140.degree.-160.degree.C and collecting the distillate in N/2 sulphuric acid. This nicotine was suitable for incorporation in smoking mixtures and did not introduce flavour off-notes. EXAMPLE 6 Fulmont 725C, an activated acid clay which, when mixed with water to form a 1 percent suspension, gives a liquor of pH 5, was used in the treatment of ethanol extracts of Nicotiana Rustica in the same way as Fulmont 300C described in Example 5. The filtrate from the reaction, containing 2.9 percent of the original nicotine and 27.9 percent of the total original solids was flavour assessed in the same manner at 4.7 percent concentration of solids and was found to give a smoke essentially similar to that from the filtrate from the Fulmont 300C treatment. For U.S. patent law, rules, and procedures see MPEP. Disclaimer. Information presented on this page while believed to be reliable, is provided "as is" with no warranties of its accuracy or timeliness. For legal advice seek help of a licensed professional. |