The present invention relates to a sheet material, in which at least one aromatic substance is incorporated, intended for the manufacture of products for smoking, such as cigarettes, cigars or analogous products, and to the products for smoking which comprise such a material.
The invention aims to prevent the loss or the premature modification of at least one aromatic substance before the product is smoked, without adversely modifying the smoke and without the substance being detectable before the product is smoked.
It further aims to release at least one aromatic substance, throughout smoking of the product, into the primary and/or secondary flow of smoke at a sufficiently low temperature so as to prevent thermal degradation of the said substance.
The sheet material according to the invention may be used as wrapping for the product for smoking.
It may also be used as reconstituted tobacco sheet, manufactured by a well-known papermaking technique .
It has already been proposed to incorporate aromatic or nonaromatic substances in the actual pulp for manufacture of paper.
Thus, in US Patent ...6042 (REYNOLDS) it is proposed to dissolve sodium and potassium salts in the initial paper pulp, but essentially with a view to improving the combustion characteristics of this paper and its strength.
In European Patent 0251132 (SHIBANAI) it is proposed to include substances, in particular perfumes, in cyclodextrins to form molecular inclusion compounds and to mix these into the pulp and water for the manufacture of paper and, in particular, wrapping paper.
In this patent, the said molecular inclusion does not have to be total, because if this were the case the paper would not itself release any odour, which is the desired aim of this patent.
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- 2 In this patent there is mention of a prolonged aromatic effect and it is due to the fact that molecules are partially adsorbed on the cyclodextrins or in emulsion in the mixture and that they progressively evaporate from the latter even when it is deposited on the pulp during manufacture. There is no suggestion anywhere in this patent that the cyclodextrins or the inclusion complexes are subjected to a thermal effect which degrades them in order to liberate the aromas.
None of the prior art documents provides any measure to ensure that the aromatic substances incorporated in the paper intended to serve as wrapping for a product for smoking are protected before consumption of the product and are liberated at a fairly low tempera15 ture, that is to say before being subjected to the high temperatures at the tip during smoking of the product, both in free combustion and in forced combustion.
The aim of the invention is, specifically, to obtain the abovementioned results and to this end it provides a process for the preparation of a sheet material intended for the manufacture of products for smoking, such as a cigar, cigarette or analogous product, in which process aromatising substances or preparations are introduced into the actual pulp for manufacture of the material, which substances or preparations are intended to be liberated only at the time of combustion of the product for smoking and are included, by molecular encapsulation or complexing, in cyclodextrins, characterised in that measures are taken to ensure that the said aromatising substances are all included in the cyclodextrins .
This total inclusion of the said substances may be effected, after the inclusion operation, by removing the non-included inclusion products of the said aromati35 sing substances, in particular those simply adsorbed on the cyclodextrins at the surface of the latter, for
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- 3 This removal of non-included substances may also be effected by drying the coated material on the paper machine itself.
As a result of this total inclusion, the said aromatic substances do not migrate into the tobacco and are preserved until, as a result of thermal degradation caused by the advance of the tip of the lit product, the cyclodextrins suddenly release some of the said aromatic substances which they protect, this sudden release continuing progressively throughout smoking of the product.
In addition to the said aromatic substances, the material may, of course, also be doped with other types of substance, for example intended to release an odour naturally, without having to be thermally degraded. They do not then have to be included or complexed in the same way as the said substances.
Examples of manufacture of materials according to the invention are given below.
- EXAMPLE 1 A mixture consisting of three parts of ^-cyclodextrin, in pulverulent form, and one part of water is kneaded at ambient temperature (15 to 25 degrees C) until a homogeneous paste is obtained.
Of the order of 13% by weight, with respect to the ^-cyclodextrin, of vanillin presolubilised in ethyl alcohol is mixed in.
The mixture is malaxated until the complex is obtained. It is then dried in a ventilated oven for about 12 h at 40 degrees C.
The complex is treated by heating at 100 degrees C for 24 hours.
The powder thus obtained is added, with stirring, to water at a temperature below 15 degrees, and to give a concentration of 4%. The water is salified if appropriate. The solution thus produced is kept at a temperature preferably below 15 degrees and introduced into the size press part of the paper machine.
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- 4 The paper machine rotates at 288 m/min over a machine width of 3.65 m. The consumption of the size press is of the order of 20 1/min.
The dosages were controlled to ensure that the desired unit weight (grams per square metre) of the paper was not modified.
The paper obtained contains 4% overall, with respect to the paper, of 0-cyclodextrin/vanillin complex. This paper does not have any odour and is used to manufacture cigarettes using a commercial cigarette light tobacco mixture.
These cigarettes were smoked by a panel of experts. The latter found a subtle and pleasant tendency towards mild sugary and vanilla-like overtones in the secondary smoke, without changing the agreeableness of the primary smoke.
- EXAMPLE 2 The procedure is carried out in the same way as in Example 1 to prepare the complex, but vanillin is replaced by -γ-undecalactone in the same proportions. The powder thus obtained is added, with stirring, to water, using the same concentration, but a suspensoid such as the bipolymer having the trade name Rhodopol BP 23, manufactured by Rhone-Poulenc, having previously been added.
The primary and secondary smoke of cigarettes manufactured using this paper and using a light tobacco mixture was strongly aromatised in the chosen overtone.
- EXAMPLE 3 (-)-Carvone is encapsulated using a mixture of 90% of fl-cyclodextrin and 10% of PMCD (partially methylated cyclodextrin manufactured by Ringdex). The procedure is carried out in the same way as for Example 1.
The smoke of cigarettes manufactured using this paper has a spearmint aromatic overtone. The irritation of the primary smoke is reduced and the tobacco taste is reinforced. The secondary smoke is milder.
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- EXAMPLE 4 A mixture consisting of one part of 0-cyclodextrin, in pulverulent form, and three parts of water is kneaded at ambient temperature (15 to 25 degrees C) until a homogeneous mixture is obtained.
1/10 part by weight of a coumarin aroma is added.
The mixture is dried at a temperature below 40 degrees C for about 12 hours.
It is then washed with a suitable solvent to remove the non-encapsulated aroma.
After grinding, the mixture is screened if necessary, to obtain a powder having a particle size of, preferably, between 1 and 100 μ.
The powder obtained is suspended in water and is used in the size press in the process for the manufacture of paper (on its own or as a mixture with other compatible additives or fillers). The concentration is adjusted as a function of the desired amount, the rate of deposition and the machine speed.
- EXAMPLE 5 25.5 kg of pulverulent ^-cyclodextrin and 2.5 kg of aroma substance are kneaded dry for 15 to 20 minutes at ordinary temperature. 51 kg of cold water are added to the 28 kg of paste obtained and the mixture is stirred for 30-40 minutes at a fairly low temperature, below 15 degrees.
The mixture encapsulated in this way is dissolved/suspended in 649 kg of water to which 0.2% of Rhodopol BP23, serving as suspensoid, has been added.
The solution obtained, which is kept at a temperature below 15 degrees, is introduced into the size press part of the paper machine. The aroma molecules which have still not been included in the cyclodextrins are removed by evaporation during drying.
The paper obtained according to the invention has no odour up to the time of its combustion and the aroma is then liberated, throughout smoking, suddenly, as a result of thermal degradation of the cyclodextrins, at
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AP3 6 4 about 280-300 degrees C, a few millimetres before the tip, without having to undergo degradation at the temperature of the tip, that is to say at 800 degrees C.
- EXAMPLE 6 A reconstituted tobacco is produced using the conventional paper making technique. However, the concentrated aqueous solution obtained from the juice resulting from maceration of tobacco dust in water is cooled and then kept at about 15 degrees C until it is introduced into the size press on the paper machine.
On the other hand, a tobacco essential oil is encapsulated in accordance with the process described in Example 4 and so as to obtain 6% of complexed essential oil.
This complex is suspended in the concentrated aqueous solution, which is introduced into the size press part of the paper machine. The rate at which the complex is introduced is chosen as a function of the flow rate of the solution, the machine speed and the rate of rise of water, in a known manner and so as to obtain 0.1% of aromatic fraction in the final product.
The reconstituted tobacco thus obtained is introduced in a proportion of 20% into the light mixture for a cigarette.
Cigarettes manufactured using this mixture are compared with other cigarettes prepared using an identical mixture but with reconstituted tobacco without cyclodextrins. The former, which tend towards the American type in a more pronounced manner than the latter, are judged by a panel of experts.
- EXAMPLE 7 A paste consisting of tobacco dust (10 to 15%), carboxymethyl cellulose (2%) and water (80 to 90%) is manufactured.
The paste thus obtained is transferred by pumping to the feed hopper of a dryer which comprises a stainless steel belt and a drying tunnel, heated to about 150 degrees C. A deposit of paste in a uniform layer
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- 7 about 0.5 mm thick is obtained on the belt of the dryer. Just before entering the drying tunnel, ^-cyclodextrin/ vanillin complex obtained according to Example 1 is poured, in powder form, onto the paste, using a vibrator.
The amount used is 5%, relative to the solids content of the paste.
The homogenised tobacco obtained after drying does not have any odour and is used to manufacture cigarillos with a commercial tobacco mixture.
These cigarillos were smoked by a panel of experts. The latter found that the smoke was milder and tended towards vanilla-like overtones.
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