The present invention relates to flavourant compositions for tobacco, to methods for their production and to tobacco products containing them.

Various kinds of flavourants have hitherto been employed in the manufacture of tobacco products. However, many flavourants are volatile; their use is thus disadvantageous in that such flavourants tend to volatilize somewhat during or after tobacco manufacture. In order to overcome the above-mentioned disadvantage, several processes have hitherto been proposed wherein flavourants have been mixed with other materials to make so-called flavourant compositions. For example, flavourant compositions have been proposed in which: flavourant is adsorbed on porous particles and dispersed in gas-permeable plastics; flavourant is spray-dried together with a water soluble high polymer whereby the flavourant is coated by the polymer, followed by further spray-drying of an emulsion prepared by dispersing the coating flavourant in oil; flavourant is fixed by a polysaccharide or the like (cf. Japanese pat. publns. Nos. 6,283/68, 12,600/70 and 23,963/68); or flavourant is encapsulated in microcapsules made of certain organic compounds (cf. Japanese pat. OS Nos. 79/73 and 63,970/76). However, the above conventional flavourant compositions also have disadvantages in that the desired volatile flavourants have not necessarily been able to be fixed in said compositions sufficiently, and further in that some of these compositions are subject to restricted industrial use in tobacco manufacture in view of undesirable chemical properties of the adsorbents, coating agents or fixing agents employed therein.

The characteristics required for an adsorbent for use in a tobacco flavourant are that it must not only have an excellent ability to fix a flavourant but also must be able to effectively release the adsorbed flavourant when the tobacco products in which the flavourant composition has been used are smoked; the adsorbents should be stable chemically and thermally, so that they do not affect the essential aroma and taste of the flavourants.

The present invention is based on the discovery that certain types of synthetic inorganic ion-exchangers ccntaining zirconium or titanium have excellent adsorbability and releasing ability therefrom for volatile and non-volatile flavourants and that these ion-exchangers do not affect the essential aroma and taste of tobacco flavourants.

According to one feature of the present invention there is provided a flavourant composition suitable for use in tobacco products comprising a flavourant adsorbed on a synthetic inorganic ion-exchanger selected from zirconium phosphate, zirconium polyphosphates, zirconium heteropolyphosphates, hydrous zirconium oxide and hydrous titanium oxide.

According to a further feature of the present invention there is provided a method for producing a flavourant composition as defined above which comprises (a) admixing a synthetic inorganic ion-exchanger as defined above with a solution of the desired flavourant in an organic solvent; (b) heating the mixture resulting from step (a); and (c) drying the ion-exchanger to remove the organic solvent therefrom whereby the desired flavourant composition is obtained.

According to a still further feature of the present invention there is provided a tobacco product containing a flavourant composition according to the invention as hereinbefore defined.

According to the present invention, tobacco flavourant is adsorbed steadily to the inorganic ion-exchanger adsorbent, while said flavourant is released from said composition readily when a tobacco product incorporating the composition is smoked. The adsorbent for use in the invention is stable and does not affect the essential aroma and taste of the tobacco flavourant used. The tobacco product, e.g., filter cigarette, according to the invention effectively produces the aroma and taste of the flavourant used when smoked.

According to the present invention, the following zirconium or titanium compounds may be employed as adsorbents of tobacco flavourants:

• zirconium phosphate;
• zirconium polyphosphates, for example, zirconium salts of pyrophosphoric acid, trimetaphosphoric acid, hexametaphosphoric acid and tripolyphosphoric acid;
• zirconium heteropolyphosphates, e.g. zirconium salts of heteropoly-acids, for example, zirconium phosphate silicate, zirconium phosphate molybdate and zirconium phosphate tungstate;
• hydrous zirconium oxide; and
• hydrous titanium oxide.

The above adsorbent compounds are all known as inorganic ion-exchangers having hitherto been chemically synthesized [cf. Bulletin of the Society of Sea Water Science, Japan, 23, 102(1969), ibid., 24, 96(1970), ibid., 25, 397(1972); The Bulletin of the Japan Society for Analytical Chemistry, 23, 1254(1974)]. Thus, for example, the zirconium compounds may be prepared by first adding phosphoric acid or an aqueous solution of an alkali metal salt of polyphosphoric acid to an aqueous solution of zirconium chloride or oxychloride to which hydrochloric acid has been added, while stirring; the precipitate of zirconium phosphate or polyphosphate formed is then filtered and washed with water to remove Cl therefrom. The precipitate is then dried and put into water again, following which it is broken to 16-80 mesh size to prepare the desired compound particles. Zirconium salts of heteropoly-acids may be prepared in similar manner using phosphoric acid together with sodium silicate, sodium tungstate or ammonium molybdate in place of phosphoric acid or an alkali metal salt of polyphosphoric acid.

The above zirconium compounds for use in the present invention are in general amorphous or crystalline particles with transparent, gray, green or white colour, the diameters of which are 1.0-0.1 mm (corresponding to 16-150 mesh), their specific gravities being about 1-2.5. The structures of these compounds have hitherto been presumed to be that of the so-called coordination compounds in which phosphoric acid-, polyphosphoric acid- or heteropoly-acid-radical is coordinated around the nucleus of ZrO, combined (or polymerized) in the form of a layer or chain or network. The molar ratio of zirconium to phosphoric acid (Zr:P) of these adsorbent compounds depends on the ratio of the raw materials having been used for their preparation. In the present invention, it is desirable to employ zirconium compounds having a molar ratio (Zr:P) of 1:1-3. The molar ratio of zirconium to silicic acid, molybdic acid or tungstic acid (Zr:Si,Zr:Mo or Zr:W) in zirconium heteropolyphosphate adsorbents is preferably 1:0.5-3.0.

Hydrous zirconium oxide and hydrous titanium oxide may, for example, be prepared by adding an equimolar amount of an aqueous solution of an alkali metal hydroxide to an aqueous solution of zirconium or titanium chloride or oxychloride; the hydrous oxides of these metals precipitated are separated, aged and dried to form amorphous or crystalline particles. These hydrous oxide compounds also present a similar external appearance to that of the above zirconium compounds containing phosphoric acid, and their structures have hitherto been presumed to be polymers of the coordination compounds represented by Zr0(OH)₂.xH₂0 and Ti0(OH)₂.xH₂0, respectively.

The adsorbent compounds for use in the present invention scarcely dissolve in water and organic solvents, and even when heated at the temperature of 800°C, they are only converted into zirconium polyphosphate or zirconium or titanium oxide each of which is stable and harmless.

According to the method of the present invention, the adsorbent compound is admixed in a solution prepared by dissolving a tobacco flavourant in a suitable organic solvent and the mixture is heated, under reflux if necessary, whereby the adsorption of flavourant to the adsorbent compound may effectively be accomplished. Suitable heating temperatures and periods of time as well as the concentration of flavourant in the solution depend on the kind of flavourants and adsorbents used. In general, heating periods of 10-120 minutes and 0.2-20% by weight of flavourant based on the weight of organic solvent used are advantageously employed. Suitable organic solvents include, for example, ethyl alcohol, benzene, ether, acetone, chloroform, hexane, ethylacetate, and the like. The adsorbent compound, having been heated with the tobacco flavourant in the organic solvent, is then dried under reduced pressure at a temperatuture below 90^o_C, desirably below 60⁰C to remove the organic solvent therefrom, whereby a flavourant composition consisting of the adsorbent and tobacco flavourant is obtained.

The tobacco flavourant usable in the present invention include nonvolatile flavourants as well as volatile flavourants both kinds of which have hitherto been used in the manufacture of tobacco. Examples of volatile flavourants include ethyl acetate, isoamyl acetate, propyl isobutyrate, isobutyl butyrate, ethyl butyrate, ethyl valerate, benzyl formate, menthol, limonene, cymene, pinene, linalool, geraniol, citronellol, citral, peppermint oil, orange oil, coriander oil, lemon oil and borneol; examples of non-volatile flavourants include tobacco extract, cocoa extract, licorice extract and fruit extract. Mixtures of volatile flavourants and nonvolatile flavourants may also be used in the invention.

Flavourant compositions of the invention prepared as above may be used in tobacco products, particularly in filter cigarettes. When applied to filter cigarettes, the flavourant composition is advantageously added to a portion of the filter tip, in contrast to flavourants or known flavourant compositions for tobacco which have usually been added to the body of the cigarette itself (i.e., blended cut tobacco). For example, the flavourant composition of the invention may be inserted between two short acetate filter tips to form a so-called triple-filter, or the composition may be dispersed among the thin fibres of an inner acetate filter tip which is then incorporated in an outer normal acetate filter tip to form a so-called dual-filter, said forms having hitherto been employed generally for the addition of charcoal particles to filter tips. The flavourant compositions of the invention may also be used by inserting them in cigarette holders through which cigarettes may be smoked. The amount of the flavourant composition to be added to a filter tip is generally 1-100 mg, preferably 5-80 mg per cigarette. The flavourant in the flavourant composition of the present invention which has been added to the filter tip of a cigarette scarcely volatilizes, when the cigarette is left to stand, but remains for a relatively long period of time therein; however, such flavourant is released readily from the composition by wet (i.e., moisture containing) smoke passing through the filter tip when the cigarette is smoked, whereby the aroma and taste of the flavourant may effectively be produced. According to the invention, the amount of tobacco flavourant capable of producing proper (or moderate) aroma and taste is far less than that of flavourant that has customarily been added to the portion of blended cut tobacco. When the cigarette according to the invention is smoked, conversion of essential aroma and taste of the flavourant does not occur.

The adsorbent compounds for use in the present invention have orally little toxicity [cf. Extract Report on Toxicity of One Thousand Main Chemicals, published by The International Technical Information Institute, Japan, pages 343 and 375]. Further, filter cigarettes of the present invention are almost equal to conventional filter cigarettes in respect of the amounts of constituents which are contained in the so-called tobacco main stream smoke and which have hitherto been regarded as being harmful to health, when such filter cigarettes are smoked. Table I demonstrates the respective amounts of constituents in tobacco main stream smoke per cigarette generated from a filter cigarette of the invention and from a control filter cigarette, said cigarette of the invention having been prepared by attaching an acetate filter tip comprising the flavourant composition, (which filter tip has been prepared in the same manner as in Example 2 described later but using zirconium phosphate as adsorbent) to a cigarette made of blended cut tobacco of bright yellow, while said control filter cigarette consists of a normal acetate filter tip and a cigarette made of the same blended cut tobacco of bright yellow as above in which however the same flavourant as in Example 2 has been sprinkled. The said main stream smoke is produced by smoking the cigarettes periodically for 2 seconds every minute (35 ml a puff) to a butt length of 30 mm. The results of the table suggest that the adsorbent as well as flavourant in the filter cigarette of the invention will not be decomposed chemically when smoked.

The invention will now be illustrated by the following examples; however the descriptions in these examples are not to be considered as limitations, since many changes in the details may be made without departing from the spirit of the invention.

Example 1

Various kinds of adsorbent compounds for use in the invention are prepared in the following manner:

• (1) Zirconium phosphate 322 g of zirconium oxychloride (ZrOC1₂.8H₂0) is dissolved in 4 litre of water, and to this solution is added 200 g of concentrated hydrochloric acid. To the resulting acidic solution is added a further aqueous solution consisting of 250 g of 98% phosphoric acid and 5 litre of water, and, after being stirred for about 20 minutes, the solution is left overnight. Precipitates of zirconium phosphate formed in the solution are centrifuged, washed with water sufficiently and dried at about 80°C. The solid matter obtained is put again in water and broken, and the resulting precipitates are centrifuged, dried and sieved to prepare the desired compound particles of 24-32 mesh.
• (2) Zirconium tripolyphosphate Prepared as in (1) above, except using 371 g of sodium tripolyphosphate (Na₅P₃0₁₀) in place of 250 ^g of 98% phosphoric acid.
• (3) Zirconium hexametaphosphate Prepared as in (1) above, except using 600 g of sodium hexametaphosphate [(NaP03)6] in place of 250 g of 98% phosphoric acid.
• (4) Zirconium pyrophosphate Prepared as in (1) above, except using 448 g of sodium pyrophosphate (Na₄P₂O₇.10H₂O) in place of 250 g of 98% phosphoric acid.
• (5) Zirconium trimetaphosphate Prepared as in (1) above, except using 312 g of sodium trimetaphosphate [(NaPO₄)₃] (prepared by heating sodium phosphate (NaH₂PO₄.2H₂O) at about 500°C for 3 hours) in place of 250 g of 98% phosphoric acid.
• (6) Zirconium phosphate silicate 322 g of zirconium oxychloride is dissolved in 3 litre of water, and to this solution is added 200 g of concentrated hydrochloric acid. To the resulting acidic solution are added an aqueous solution prepared by dissolving 552 g of sodium silicate (Na₂Si0₃) in 10 litre of water and an aqueous solution consisting of 100 g of 98% phosphoric acid and 3 litre of water; the mixture is stirred for about 30 minutes and precipitates of zirconium phosphate silicate formed in the solution are separated. Subsequent procedures are conducted in the same manner as in (1) above, to prepare particles of the desired compound.
• (7) Zirconium phosphate tungstate Prepared as in (6) above, except using 330 g of sodium tungstate (Na₂W0₄.2H₂0) in place of 552 g of sodium silicate.
• (8) Zirconium phosphate molybdate Prepared as in (6) above, except using 600 g of ammonium molybdate [(NH₄)₆Mo₇O₂₄.4H₂O] in place of 552 ^g of sodium silicate.
• (9) Hydrous titanium oxide 190 g of titanium tetrachloride (TiC1₄) is dissolved in 15 litre of water, and the pH of the solution is adjusted to 7 by adding an aqueous solution of sodium hydroxide dropwise. The precipitates formed are filtered and dried to prepare amorphous particles of the desired compound.
• (10) Hydrous zirconium oxide Prepared as in (9) above, except using 322 g of zirconium oxychloride in place of 190 g of titanium tetrachloride.

0.5 g of each of the adsorbent compounds prepared as above is mixed in individual solutions prepared by dissolving 0.1 g of ethyl valerate in 30 ml of ethyl alcohol, and the mixtures are heated under reflux for 60 minutes. The adsorbents in the mixtures are dried at 40⁰C under reduced pressure, whereby particles of the respective flavourant compositions in each of which ethyl valerate is adsorbed are prepared. Similar procedures are conducted using 1-menthol in place of ethyl valerate, whereby particles of the respective flavourant compositions in each of which 1-menthol is adsorbed are prepared.

These flavourant compositions are left at a temperature of 20⁰C and a relative humidity of 60%,and the amounts of flavourants remaining in the flavourant compositions are estimated at predetermined intervals by gas-chromatography using SHIMAZU GC-4CM Type apparatus [with a filler of BGA 10%/chromsorb AW(60-80 mesh); carrier gas (N₂) of 60 ml/min]. The amounts of flavourant as percentages of the amounts of flavourant initially present are shown in Table II. As a control, the same flavourants as the above are impregnated into filter papers (Toyo Roshi No. 3), which are then left and tested in the same manner as above; the data of these tests are annexed to Table II as a control test. From the table, it can be seen that the flavourants in the flavourant compositions of the invention are released at a relatively slow rate, while the flavourants in the control test are released rapidly.

Example 2

0.5 g each of zirconium phosphate, zirconium hexametaphosphate, zirconium phosphate silicate and hydrous titanium oxide (prepared as in Example 1) is mixed in individual solutions prepared by dissolving 0.125g of orange oil in 30 ml of alcohol, and the mixtures are heated under reflux for 30 minutes. The adsorbent compounds in the mixtures are dried at 40°C under reduced pressure, whereby flavourant compositions in each of which orange oil has been adsorbed are prepared.

10 mg of each of the above flavourant compositions is dispersed among the fibres of individual inner acetate filter tips which are then incorporated with normal outer acetate filter tips to form dual-filters; these dual-filters are attached to cigarettes made of the same blended cut tobacco as has hitherto been used for "hi-lite" (trademark; mfd. by The Japan Tobacco & Salt Public Corp.), whereby filter cigarettes according to the invention are prepared. A control filter cigarette is prepared by using a normal filter tip and a cigarette made of the same blended cut tobacco as above in which however orange oil has been sprinkled in conventional manner so that the amount thereof per one cigarette is equal to that of orange oil per one cigarette of the invention prepared as above.

The cigarette of the invention and the control cigarette are left in an atmosphere of temperature 20⁰c and relative humidity 60% for sixty days, and then subjected to a sensory test. The procedures of the test are carried out as follows: the aroma, taste and the like which arise when the cigarettes are smoked are evaluated by a panel consisting of twenty persons, applying the so-called pair test method. The results of the test are shown in Table III; the figures represent the number of person who have praised a cigarette of the present invention as compared to the control.

From the table the cigarettes of the present invention are found to be superior to the control cigarette, especially in aroma and taste. In addition, it was found that the so-called room-aroma achieved when the cigarettes of the invention had been smoked was markedly intense, such a phenomenon not having been found for the control cigarette.

Example 3

Three kinds of filter cigarettes of the present invention are prepared in the following manner in which the same blended flavourant, blended cut tobacco and filter tip as those having hitherto been used for the manufacture of "Seven Stars" (trademark; mfd. by The Japan Tobacco & Salt Public Corp.) are employed, said blended flavourant having however been used for "Seven Stars" such that an alcohol solution thereof is added to blended cut tobacco in conventional manner. The said filter tip consists of a so-called inner charcoal filter tip, made by dispersing charcoal particles among the fibres of a normal acetate filter tip, and outer normal acetate filter tip without charcoal particles: 0.5 g of hydrous zirconium oxide which has been prepared as in Example 1 is mixed in each of three solutions prepared by dissolving respectively 0.6 g, 0.3 g and 0.2 g of the blended flavourant in 30 ml each of ethyl alcohol, and the resulting mixture is heated under reflux for 60 minutes. The adsorbent compound in the mixture is dried at 40°C under reduced pressure to remove ethyl alcohol therefrom, whereby are prepared flavourant compositions in which 0.6 g, 0.3 g and 0.2 g respectively of the blended flavourants have been adsorbed.

Five (5) mg of each of the above flavourant compositions is filled between said inner charcoal filter tip and outer normal acetate filter tip to form triple-filters, and these triple-filters are attached to cigarettes made of the blended cut tobacco, whereby are prepared three kinds of cigarettes using the respective flavourant compositions of 0.6 g, 0.3 g and 0.2 g blended flavourants which are referred to hereinafter as cigarette I, cigarette II and cigarette III of the invention, respectively; the amount of blended flavourant per one of said cigarette I of the invention corresponds to that of the blended flavourant per one cigarette of commercial "Seven Stars".

The cigarettes of the invention prepared as above and "Seven Stars" (as control cigarette) are left and tested in the same manner as in Example 2.

The results of the test for cigarettes which were left for only seven days are as follows: all the persons of the panel agreed with each other that cigarette I of the invention had too rich aroma and taste, and 15 persons agreed also that cigarette II of the invention had relatively rich aroma and taste while the other 5 persons indicated that the aroma and taste of cigarette II of the invention were moderate. For cigarette III of the invention, 18 persons agreed that it had moderate aroma and taste, being almost equal to control cigarette.

Next, the results of the test for the cigarettes left for sixty days are as follows: while 17 persons in the panel indicated that the aroma and taste of the control cigarette were decreased somewhat to yield tobacco irritation and astringency, 17 persons commented that the aroma and taste of cigarettes I, II and III of the invention were almost the same as those of cigarettes I, II and III left for seven days respectively.

The above results show that for the tobacco products of the present invention about a third of the amount of blended flavourant which has hitherto been added to blended cut tobacco as in "Seven Stars" serves to yield corresponding aroma and taste to those of the latter, and that the aroma and taste of a cigarette of the invention may also be obtained after the cigarette has been left for a relatively long period of time.

Example 4

By using the same blended flavourant and blended cut tobacco as has hitherto been used for the manufacture of "hi-lite", a filter cigarette according to the present invention as well as three kinds of control filter cigarettes are prepared as follows:

• Cigarette of the invention: 0.5. g of zirconium phosphate silicate prepared as in Example 1 is mixed with a solution prepared by dissolving 0.125 g of the blended flavourant in 30 ml of ethyl alcohol and the resulting mixture is heated under reflux for 30 minutes. The adsorbent in the mixture is dried at 40°C under reduced pressure. Subsequent procedures are conducted in the same manner as in Example 2 to prepare a filter cigarette of the invention, with the proviso that the amount of the blended flavourant per one cigarette is made to be the same as that of the blended flavourant having hitherto been used per one cigarette of "hi-lite". This proviso is also applicable to control cigarettes I, II and III described below.

Control cigarette I: 1.25 mg of blended flavourant is injected into an acetate filter tip using a needle and the filter tip is attached to a cigarette made of blended cut tobacco.

Control cigarette II: the same procedures are carried out as in the preparation of the above cigarette of the invention except that charcoal particles of 24-32 mesh are used in place of zirconium phosphate silicate.

Control cigarette III: the same procedures are carried out as in the preparation of the above cigarette of the invention except that zeolite particles are used in place of zirconium phosphate silicate and the zeolite particles are granulated after adsorption of the flavourant, so as to be 24-32 mesh.

The cigarette of the invention as well as the control cigarettes I, II and III are left and tested in the same manner as in Example 2. The results of the test are as follows.

For control cigarette I: a cigarette left for seven days has little aroma and taste, though it has a slight aroma of menthol. A cigarette left for sixty days has no aroma but produces irritation, astringency, offensive odour and offensive taste.

For control cigarette II: the aroma and taste of a cigarette left for seven days as well as the aroma and taste of a cigarette left for sixty days decrease and these cigarettes have a charcoal taste, thus resulting in a cigarette quite different in aroma and taste to "hi-lite".

For control cigarette III: a cigarette left for seven days has little aroma and taste, but a cigarette left for sixty days loses all aroma and taste while producing bitterness and astringency.

For the cigarette of the invention: the aroma and taste of cigarettes left for sixty days as well as seven days are markedly intense so as to remove offensive odour and offensive taste of tobacco. Many of the persons in the panel commented that it would be better to decrease the amount of the belended flavourant to be used therefor.

Example 5

1 g of zirconium tripolyphosphate prepared as in Example 1 is mixed with a solution prepared by dissolving 0.1 g of alcoholic extract of hydrangea leaves, 0.1 g of tobacco extract, 0.05 g of chocolate flavour, 0.01 g of y-decalactone and 0.01 g of ethyl valerate in 50 ml of ethyl alcohol, and the resulting mixture is heated under reflux for 40 minutes. The adsorbent compound is dried at 35°C under reduced pressure to prepare the flavourant composition on which the above tobacco flavourants have been adsorbed. 100 mg cfthe flavourant composition is filled between two short normal acetate filter tips which have been set in a cigarette holder. A cigarette having no filter is fitted to the holder and smoked through the filter tip, whereby excellent aroma and taste are produced.