NO130176B - - Google Patents

Description

Method of manufacture of

a raw material for smoke mixtures.

This invention relates to the production of an improved smoking material from tobacco.

In the applicant's Norwegian patent no. 116 233 it is proposed to

replace at least part of the tobacco in smoking mixtures with a modified

fissed carbohydrate material produced by catalytic degradation of carbohydrate at 100-250°C until the weight of the degraded material

ale is less than 90% by weight of the original carbohydrate.

It has now surprisingly been found that catalytic thermal degradation

ging of tobacco also gives improved tobacco flavor when smoking.

The method according to the invention for producing a

improved material suitable for smoking mixtures mainly involves subjecting the tobacco to a catalytic degradation process by

a temperature of at least 100°C, suitably 100-300°C and preferably 100-250°C, especially 160-250°C, until the weight of the built-up material is less than 90% by weight of the original tobacco. The weight of the built-up material should ideally not be less than 70% of the original tobacco.

All types of tobacco can be used in the method of the invention, including cigarette tobacco such as smoke-cured Virginia (FCV) tobacco as well as stronger types of tobacco such as Burley and Rustica tobacco.

The catalyst used in the present method can be any substance which accelerates the thermal breakdown of tobacco or lowers the breakdown temperature. Acids are particularly effective, and preferred catalysts are strong acids and salts of strong acids with weak bases. Mineral acids, for example sulfuric acid, phosphoric acid and hydrochloric acid can be used, and suitable salts of weak bases include ammonium sulphate, diammonium hydrogen phosphate, ferric chloride and especially ammonium sulphamate. Alkaline substances are also effective catalysts, e.g. alkali hydroxides, such as sodium hydroxide, and alkali salts of weak acids, for example sodium carbonate. When alkaline catalysts are used, however, the built-up material should preferably be washed mainly free of catalyst before it is used for smoking.

The catalyst is preferably used in amounts of 1-20% by weight, preferably 3-8% by weight of the tobacco.

The method according to the invention can be carried out with the tobacco in any suitable form, e.g. in the form of leaves, powder or sheets. Other substances which are inert under the degradation conditions can optionally be added. Thus, neutral salts and inert binders can be used if desired.

All volatile materials are given the opportunity to escape from the zone where the thermal breakdown takes place. The procedure has been shown to have a degrading effect on cellulose and other carbohydrate components in the tobacco, during which water and other volatile substances escape.

The duration of the process depends on the temperature, the catalyst, the physical state of the tobacco and the degree to which the desired effect is achieved.

The process changes the color of the tobacco to dark brown-black. Quite surprisingly, however, the thermally degraded material exhibits improved tobacco aroma when smoked, which shows that the aroma substances present have an unexpected stability under the conditions used.

When tobacco is heated in the absence of catalyst, it can lose weight, and when heating is continued, a residue weighing less than 90% of the original tobacco can be obtained. Such residues have not improved the smoke flavor compared to the original tobacco, and they have determined a worse smoke flavor than the materials produced according to the present method. It is within the scope of the invention to heat tobacco in the absence of a catalyst and then continue the heating in the presence of a catalyst.

A further advantage of the present method is that it provides a reduction in formaldehyde release in the smoke from the products compared to the untreated tobacco. Formaldehyde is known to be a serious ciliatoxic component in tobacco smoke.

When an acid catalyst, e.g. sulfuric acid is used in the present method, it is advantageous to neutralize any acid residues in the thermally degraded material by adding ammonia.

The thermally degraded material obtained in the present method can, if desired, be mixed with other materials that are normal components of smoking mixtures, for example tobacco, carbohydrates, modified carbohydrates, especially thermally degraded carbohydrates (and in particular thermally degraded cellulose) produced according to the method according to Norwegian patent no. 116 233, or other smoke-producing materials and, if desired, other modified substances which are usually used in smoke mixtures.

Thus, e.g. smoking mixtures containing thermally degraded material produced according to the present method also contain glow-promoting catalysts, materials that improve ash strength or colour, nicotine, flavoring substances, moisture-preserving substances, drugs or inorganic fillers.

As glow-promoting catalysts that act to "keep the fire going", alkali metal compounds are preferred.

Ammonium, alkali metal or alkaline earth metal salts can be used as materials to improve the condition of the ash, and of these, magnesium, calcium or ammonium salts are preferred. Bentonite is a particularly effective ash strengthening agent.

A number of beneficial flavorings can be added to the mixture. These include tobacco extracts, organic esters, essentials

oils, menthol, tonka beans or vanillin.

Glycerol and glycols such as ethylene glycol and di-, tri-

and tetraethylene glycol are suitable humectants.

Inorganic fillers are mixed in with the advantage of regular

learning of the combustion rate of the mixture. By unbalancing the io-

ners that accelerate combustion against ions that delay combustion, cf. British Patent No. 1,299,296, acceptance can be obtained

table burning rates even when large amounts (for example 40% or .more) of fillers are mixed. Carbonates, especially calcium and magnesium carbonates, are well-suited fillers, espe-

or when they are used in combination to achieve a satisfactory combustion rate. Porous, inert fillers can facilitate combustion, give a more open texture or structure to the mixture and thereby facilitate the access of oxygen.

It is desirable that the smoke mixtures simulate tobacco, and

the thermally degraded material is therefore preferably produced in the form of sheets, and, when used for cigarettes or pipe filling,

in unraveled form. For the production of sheet-shaped smoke mixtures, the thermally reduced material, if already present in sheet form, can be simply treated with the desired additives and unraveled. Thermally degraded material in other forms or in sheet form which is far too weak to be unraveled satisfactorily can be crushed into powder and converted into a sheet by the methods used in the production of reconstituted tobacco.

E.g. the material can be mixed with a solution of binder so

as a water-soluble cellulose derivative, polyvinyl alcohol, starch, pectin, gum or mucilage substances, formed into a film and dried. Water-soluble methyl cellulose or sodium carboxymethyl cellulose, preferably of such a nature that a 2% aqueous solution has a visco-

site of at least 150O centipoise at 25°C can be advantageously used as a binder. Other ingredients can be used together with the ter-

misc built-up material and the binder. Soluble ingredients can, if desired, be showered or sprayed onto the sheet-shaped mixture.

For use in cigarettes or pipes, the unraveled mixture is preferably conditioned in a moist atmosphere to a water content of 5-15% by weight.

The method according to the invention can be used with advantage

to improve the aroma of poor quality tobacco material

(e.g. the stem or cane of the tobacco plant and fine powder-

material) of the kind used in reconstituted tobacco.

The following examples will further illustrate the invention. All parts are listed by weight. The aroma determinations mentioned in the examples were carried out by a panel of smokers who were specially selected because they had, over a long period of time, shown a reliable and good judgment in relation to tobacco aroma, and also had extensive experience in testing the aroma of tobacco cigarettes.

Example 1

Pulverized smoke-cured Virginia (RMV) tobacco was impregnated with an aqueous solution of ammonium sulfamate and dried to a powder containing 5% ammonium sulfamate. The powder was heated for 15 minutes at 225°C in an oven, during which it lost 20% of its original weight.

The resulting thermally decomposed product, a dark brown to black powder, was slurried in an aqueous solution of sodium carboxymethyl cellulose (SCMC) and the ingredients listed below, and the slurry was spread into a film and dried, after which the film had the following composition.

The film was unraveled and cigarettes were produced. When smoked, they had a tobacco aroma.

Example 2

This shows that the thermally degraded RMV tobacco had a better tobacco aroma than an untreated RMV tobacco. 95 parts smoke-ripened Virginia tobacco (RMV) was sprayed with a 5% aqueous solution of ammonium sulfamate. The tobacco was air-dried and then heat-treated at 220-225°C for 20-25 minutes, yielding 75 parts of a dark brown material, which was ground in a ball mill and converted into a sheet as follows. 4 parts of sodium carboxymethyl cellulose were dissolved in 160 parts of water with stirring, and an aqueous solution of 5.6 parts of glycerol, 2.0 parts of potassium citrate and 1.6 parts of citric acid in 40 parts of water was added. A dry mixture consisting of 4.0 parts calcium carbonate and 22.8 parts of the dark brown material was now added. The resulting slurry was stirred for at least 1 hour and then cast on a dryer to a film weighing 48-52 g/m2 on a dry basis.

The film was unraveled and cigarettes produced. These cigarettes were compared to similar cigarettes containing untreated ball mill ground RMV tobacco. The panel unanimously preferred the cigarette containing the thermally degraded tobacco because of its much stronger tobacco flavor.

Example 3

This example illustrates the use of sulfuric acid as a catalyst and again shows that a better tobacco flavor is obtained with the thermally reduced RMV tobacco than with untreated RMV tobacco.

95 parts smoke-cured Virginia tobacco was sprinkled with

a solution of 5 parts concentrated sulfuric acid in 100 parts water. The tobacco was then air dried and then heat treated at 220-225°C for 20-25 minutes, yielding 80 parts of a dark brown material, which was ball milled and converted into a sheet as follows: 4.0 parts sodium carboxymethyl cellulose was dissolved in 160 parts water with stirring, and an aqueous solution of 5.6 parts glycerol, 2.0 parts potassium citrate and 1.6 parts citric acid in 40 parts water was added. A dry mixture containing 4.0 parts calcium carbonate and 22.8 parts of the dark brown material was now added. The resulting slurry was stirred for at least 1 hour, then cast on a drier to a film weighing 48-52 g/m 2 on a dry basis.

The film was unraveled and cigarettes produced. The panel's assessment of these cigarettes' aroma compared to similar cigarettes made from ball mill ground, untreated tobacco showed that the treated tobacco had a better tobacco aroma than the untreated tobacco. The participants in the panel all agreed on this.

Example 4

This example shows that thermally degraded Burley tobacco had an improved aroma. 95 parts Burley tobacco was sprayed with 5 parts ammonium sulfamate in 95 parts water and heated at 220-225°C for 20 minutes, yielding 83.6 parts of a dark brown material, which was ball milled and converted to a film as follows :

4.0 parts of sodium carboxymethyl cellulose were dissolved in

160 parts water with stirring, and an aqueous solution of 5.6 parts glycerol, 2.0 parts potassium citrate and 1.6 parts citric acid in 40 parts water was added. A dry mixture containing 4.0 parts calcium-

carbonate and 22.8 parts of the dark brown material were now added.

The resulting slurry was stirred for at least 1 hour and then cast on a dryer to a film weighing 48-52 g/m2 on a dry basis.

The film was unraveled and cigarettes produced. A panel

of smokers unanimously opined that these cigarettes exhibited improved tobacco flavor compared to similar cigarettes containing ball mill Burley tobacco that was not thermally reduced. The regular Burley tobacco cigarette had only a faint tobacco/woody aroma compared to a more distinct tobacco aroma of the cigarette containing thermally degraded Burley tobacco.

Example 5

This example illustrates that the thermally degraded RMV-

tobacco had a better tobacco flavor than RMV tobacco that had been heated under similar conditions without catalyst.

4.0 parts sodium carboxymethyl cellulose was dissolved in 160 parts water with stirring, and an aqueous solution of 5.6 parts glycerol, 2.0 parts potassium citrate and 1.6 parts citric acid in 40 parts water was added. A dry mixture containing 4.0 parts calcium carbonate and 22.8 parts of a material (ground to pass a 120 "B.S. Sieve") prepared by heating smoke-cured fine-cut Virginia tobacco without catalyst at a temperature of 220-225° C for 20-25 minutes with a 20% weight loss, was now added.

The resulting slurry was stirred for at least 1 hour and then cast on a drier to a film weighing 48-52 g/m 2 on a dry basis.

The film was unraveled and cigarettes produced. Aroma assessment of these cigarettes by a panel of experts and comparison with similar cigarettes produced by the third-

misc downgraded RMV tobacco (see Example 2) showed that the panel unanimously preferred the cigarettes containing the catalyst and heat-treated tobacco.

Example 6

This example shows that the thermally degraded Burley

tobacco has a better tobacco flavor than Burley tobacco that has been heat-treated in a similar way without a catalyst.

Burley tobacco was heated without catalyst at a temperature of 220-225°C for 20-25 minutes, during which the material lost 13.4% of its weight. This material was ground to a powder and further reprocessed as follows:

4.0 parts of sodium carboxymethyl cellulose were dissolved in

160 parts water with stirring, and an aqueous solution of 5.6 parts glycerol, 2.0 parts potassium citrate and 1.6 parts citric acid in 40 parts water was added. A dry mixture of 4.0 parts calcium carbonate and 22.8 parts of the above heat-treated Burley tobacco was then added. The resulting slurry was stirred for at least 1 hour and then cast on a drier to a film weighing 48-52 g/cm 2 on a dry basis.

The film was unraveled and cigarettes produced. Evaluation of the aroma of these cigarettes by a panel of experts and comparison with cigarettes containing powdered thermally degraded Burley tobacco prepared as described in Example 4,

showed that the panel unanimously preferred the latter cigarettes because of their better tobacco flavor. The cigarettes containing the Burley tobacco that were heated without a catalyst had essentially the same flavor and aroma as burning cellulose and very little tobacco flavor.

Example 7

95 parts smoke-cured Virginia tobacco was sprinkled with

an aqueous solution of 5 parts ammonium sulfamate in 95 parts water. The tobacco was now air-dried and heated at 180°C for 6 hours, resulting in a weight loss of 20%. The product was ground to pass a 120 "B.S. Sieve".

4.0 parts of sodium carboxymethyl cellulose were dissolved in

160 parts water with stirring, and an aqueous solution of 4.8 parts glycerol, 2.0 parts potassium citrate and 1.6 parts citric acid in 40 parts water was added. A dry mixture of 4.0 parts of calcium carbonate and 22.8 parts of therein heat-treated RMV tobacco prepared as described in the previous section was added. The resulting slurry was stirred for 1 hour, then cast on a drier to a film weighing 48-52 g/m 2 on a dry basis. The film was unraveled and cigarettes made.

These cigarettes were compared with similar cigarettes containing ball-milled RMV tobacco, and the panel found that the tobacco character of the smoke was increased in the cigarettes containing ammonium-sulfamate-catalyzed heat-treated Virginia tobacco.

Claims (1)

Process for producing an improved material for use in smoking mixtures, characterized in that tobacco is subjected to catalyzed degradation at a temperature of at least 100°C until the weight of degraded material is less than 90% of the weight of the original tobacco.