EP3315031A1

EP3315031A1 - Composition

Info

Publication number: EP3315031A1
Application number: EP16830215.6A
Authority: EP
Inventors: Megumi KATSUOKA; Takahisa KATSUOKA
Original assignee: Japan Tobacco Inc
Current assignee: Japan Tobacco Inc
Priority date: 2015-07-24
Filing date: 2016-06-24
Publication date: 2018-05-02
Also published as: EP3315031A4; TW201707584A; JP6673564B2; WO2017018110A1; JPWO2017018110A1

Abstract

The present invention provides: a composition that is able to efficiently reduce unpleasant odors of sidestream smoke when added to tobacco leaves; a tobacco raw material containing the composition and tobacco leaves; and a method for producing same. Provided is the composition, which contains diethyl malate and at least one type selected from among ethyl levulinate, ethyl palmitate and triethyl citrate.

Description

[Technical Field]

The present invention relates to a composition, and more specifically, for example, a composition for a tobacco product.

[Background Art]

Reducing the smell of cigarette sidestream smoke is highly needed, and fragrances for achieving the reduction have been actively studied. In order to further improve the function of reducing smell of cigarettes and expand the variety of products meeting preference of customers, it is always sought to have technical knowledge on types of compounds in fragrances and combinations of the compounds.
Meanwhile, the smell may be reduced by treating tobacco leaves, although few studies have been done. Known cases for seeking improvement of smoke flavour of mainstream smoke include a technique in which some of tobacco components are esterified and treated with nitrous acid (Patent Document 1) and a method in which shredded tobacco is cured in an air atmosphere under sealed conditions in order to enhance ester flavour components or components contributing to smoke flavour (Patent Document 2).

[Citation List]

[Patent Document]

[Patent Document 1] Japanese Examined Patent Publication No. S45-32917
[Patent Document 2] WO 2013/098920

[Non-Patent Document]

[Non-Patent Document 1] Shimizu and Takei, Journal of the agricultural chemical society of Japan, 23, 286 (1949)

[Summary of Invention]

[Technical Problem]

The technique disclosed in Patent Document 1 requires several steps, rendering the process complicated. In addition, in this technique, components in tobacco subjected to esterification reaction are those fractioned in a hexane phase, and thus the amount and type of esters produced are limited.
In the technique disclosed in Patent Document 2, reaction (curing) requires a long period of time (1 week to 3 months).
Moreover, both techniques disclosed in Patent Document 1 and 2 focus on the change in smoke flavour of mainstream smoke and do not seek to reduce smell of sidestream smoke. Further, the amount and type of esters produced are limited, and thus it is hard to say that smell of sidestream smoke is efficiently reduced by the above manners. In both techniques disclosed in Patent Document 1 and 2, it is studied how to make changes in flavour of tobacco per se through treatment of tobacco leaves without addition of fragrances, meaning that the studies focus on the changes in smoke flavour of mainstream smoke and do not seek reducing the smell of sidestream smoke.
Under the above circumstances, an object of the present invention is to provide a composition that can efficiently reduce the smell of sidestream smoke when added to tobacco leaves; a tobacco material including the composition and tobacco leaves; and a method for producing the foregoing.

[Solution to Problem]

As a result of extensive studies carried out by the inventor of the present invention, it is found that the above object can be achieved by the composition containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate, reaching to the present invention.
Thus, the present invention is as follows.

[1] A composition containing diethyl malate and one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate.
[2] The composition according to [1], which is for a tobacco product.
[3] The composition according to [1] or [2], wherein diethyl malate is contained at 5% to 95% by weight relative to the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
[4] The composition according to any of [1] to [3], wherein diethyl malate is contained at 20% to 60% by weight relative to the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
[5] A tobacco material including tobacco leaves and the composition according to any of [1] to [4].
[6] A method for producing a composition containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate, the method including an extraction step of obtaining a liquid extract of tobacco leaves by using ethanol and an esterification reaction step of adding a catalyst to the liquid extract obtained in the extraction step to carry out esterification reaction.
[7] The method according to [6], wherein the catalyst is a solid acid and the method includes a step of removing the added solid acid catalyst prior to esterification reaction.
[8] A method for producing a composition including diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate,
- the method including a step of obtaining a liquid extract of tobacco leaves by using water or a solvent containing water and ethanol; and the following step (1) or (2):
  1. (1) a step of concentrating the liquid extract obtained in the extraction step in order to obtain a concentrate, then adding ethanol to the concentrate; or
  2. (2) a step of adding ethanol to the liquid extract obtained in the extraction step; and
- an esterification reaction step of adding a catalyst to any of the following (i) to (iv), followed by esterification reaction:
  1. (i) a liquid extract obtained in the extraction step;
  2. (ii) a concentrate obtained in the step (1);
  3. (iii) a solution obtained after the step (1); or
  4. (iv) a solution obtained after the step (2).
[9] The method according to [8], wherein the catalyst is a solid acid, and the method includes a step of removing the added solid acid catalyst prior to esterification reaction.
[10] A method for producing a tobacco material containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate, the method including an esterification reaction step of carrying out esterification reaction of a material obtained by mixing tobacco leaves, ethanol and a catalyst.
[11] The method according to [10], wherein the catalyst is a solid acid, and the method includes a step of removing a solid acid catalyst prior to esterification reaction.
[12] The method according to any one of [6] to [11], wherein the esterification reaction step is carried out for 5 to 500 minutes at a temperature of 60°C to 150°C.
[13] The method according to any of [6] to [11], wherein the catalyst is a solid acid having a desorption amount of 10 µmol/g or more at a desorption peak at less than 500°C in an ammonia TPD method.
[14] The method according to any of [6], [8], [10] and [12], wherein the catalyst is a liquid acid.

[Effects of Invention]

When the composition of the present invention is added to tobacco leaves, or when a tobacco material including the composition and tobacco leaves is used, the smell of sidestream smoke can be efficiently reduced.

[Brief Description of Drawings]

[Fig. 1]
Fig. 1 shows the type and relative amount of esters obtained after esterification of an ethanol extract of Japanese Flue-Cured tobacco. Esterification conditions: 120°C, 1 h, the amount of the catalyst: 50% by weight per wet weight of tobacco.
[Fig. 2]
Fig. 2 shows the ammonia TPD analysis conditions.
[Fig. 3]
Fig. 3 shows the ester content of treatment liquids of Example 2 and Comparative Example 1. Esterification conditions: 120°C, 3 h, the amount of the catalyst added: 50% by weight per wet weight of tobacco.
[Fig. 4]
Fig. 4 shows the result of the tobacco smell sensory evaluation before and after the treatment in Example 1 using Japanese Flue-Cured tobacco.
[Fig. 5]
Fig. 5 shows the result of the tobacco smell sensory evaluation when the treatment liquid of Example 2 obtained with Flue-Cured tobacco stems was used.
[Fig. 6]
Fig. 6 shows the result of the tobacco smell sensory evaluation obtained with commercial product cigarettes to which treatment liquids of Example 1 and Comparative Example 1 using Japanese Flue-Cured tobacco were added, respectively.
[Fig. 7]
Fig. 7 shows the evaluation result of the effect of the type and amount of esters on tobacco smell.
[Fig. 8-1]
Fig. 8-1 shows the examination result of the effect of reducing tobacco smell by mixtures of ethyl palmitate and diethyl malate.
[Fig. 8-2]
Fig. 8-2 shows the examination result of the effect of reducing tobacco smell by mixtures of triethyl citrate and diethyl malate.
[Fig. 9]
Fig. 9 shows the examination result of the effect on tobacco smell by diethyl malate.
[Fig. 10]
Fig. 10 shows the amount of ethyl esters produced in Examples 3 to 5. Tobacco leaves: Japanese Flue-Cured tobacco.
[Fig. 11]
Fig. 11 is a chromatogram obtained by analysis of the treatment product in Example 6.

[Description of Embodiments]

The present invention is hereinafter specifically described by way of embodiments and examples which do not limit the present invention and may be arbitrarily modified without departing from the scope of the present invention.
The composition of the present invention contains diethyl malate and one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate.
Namely, the composition of the present invention contains not only diethyl malate but also one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate in combination with diethyl malate.
By not only combining diethyl malate but also one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate in combination with diethyl malate to configure a composition, the effect of reducing tobacco smell is increased when the composition is added to tobacco leaves or when a tobacco material containing the composition and tobacco leaves is used.
The composition of the present invention containing diethyl malate and one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate may be prepared by mixing the isolated compounds or, as in the method for producing the composition of the present invention described hereinafter, may be prepared by isolating and purifying malic acid, levulinic acid, palmitic acid and citric acid from a treatment liquid obtained through the step of allowing reaction of malic acid, levulinic acid, palmitic acid and citric acid in tobacco leaves with ethanol and carrying out esterification.
The method for isolation and purification in this context may be carried out with well-known chromatography including, for example, ion-exchange chromatography and reverse phase high performance liquid chromatography. The conditions for the chromatography may be those well-known.
The composition of the present invention is preferably for a tobacco product.
The term "for a tobacco product" means that the composition may be added to tobacco leaves for preparation of a tobacco product or may be used as a tobacco material for production of a tobacco product.
The composition of the present invention contains diethyl malate at preferably 5% by weight or more, more preferably 10% by weight or more and still more preferably 20% by weight or more relative to the total content of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the composition. Meanwhile, the content of diethyl malate is preferably 95% by weight or less, more preferably 80% by weight or less, still more preferably 60% by weight or less relative to the total content of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
The total content of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate relative to the total amount of the composition of the present invention may be 5% to 95% by weight in an embodiment, 10% to 80% by weight in a preferable embodiment and 20% to 60% by weight in a more preferable embodiment.
The content of each of ethyl levulinate, ethyl palmitate and triethyl citrate in the composition of the present invention is not particularly limited as far as the content is in the range that does not impair the effect of the present invention: however, as an example, the weight proportion thereof may fulfil the relationship of ethyl levulinate > ethyl palmitate > triethyl citrate in an embodiment.
The ethyl esters may be combined respectively with diethyl malate or more than one ethyl ester may be combined with diethyl malate.
Ethyl palmitate is preferably combined with diethyl malate. One or both of ethyl levulinate and triethyl citrate may be combined with the above combination.
When the composition is added to tobacco leaves, the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the composition may be 0.01% by weight or more, preferably 0.05% by weight or more and more preferably 0.1% by weight or more relative to the material wet weight of tobacco leaves in an embodiment. Meanwhile, in this context, the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the composition may be 10% by weight or less relative to the material wet weight of tobacco leaves in an embodiment.
When a tobacco material containing the composition and tobacco leaves is configured (when tobacco leaves or shredded tobacco leaves are contained), the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate, for example, may be 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more relative to the material wet weight of tobacco leaves in the tobacco material in an embodiment.
Meanwhile, in this context, the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate may be 10% by weight or less in an embodiment.
When the composition of the present invention is added to tobacco leaves, isolated ethyl ester compounds may be mixed to obtain the composition. Isolated diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate may be ones commercially available or may be obtained by fractionation of synthesised ethyl esters so as to adjust the concentrations thereof.
As described hereinafter, the composition may be prepared by obtaining a solution containing malic acid, levulinic acid, palmitic acid, citric acid and carbohydrates (precursors of levulinic acid) from tobacco leaves by extraction treatment of the tobacco leaves, and isolating and purifying a treatment liquid containing ethyl esters obtained by mixing the obtained liquid extract with a solution containing ethanol and carrying out esterification.
The method for isolation and purification in this context may be carried out by well-known distillation under reduced pressure or chromatography including, for example, adsorption chromatography using a rotary evaporator or silica gel. The conditions for the isolation and purification may be those well-known.
Tobacco leaves used may be those described hereinafter as well as those without shredding, tobacco leaves shredded into predetermined shapes, tobacco powder having a predetermined size or lamina without shredding.
Tobacco leaves to be subjected to extraction may contain water.
A specific method for preparing the composition when the ethyl ester compounds are obtained by reactions may include the following procedures.
To tobacco leaves, water, ethanol or a mixture thereof is added to effect extraction at a temperature of around normal temperature to 70°C and the liquid extract is separated from the extraction residue.
The solvent used for extraction may be water or ethanol alone or a mixture thereof.
When the solvent used for extraction is water or a mixture of water and ethanol, the amount of compounds extracted and to be subjected to esterification reaction (including organic acids, saccharides and carbohydrates) may be increased. However, water may be an inhibitor of esterification reaction. Therefore, it is desirable to adjust the amount of water in the reaction solution by concentrating the liquid extract to obtain a concentrate to which ethanol is then added or adding ethanol to the liquid extract so that the water concentration is sufficiently low. Well-known concentration methods may be used.
The conditions during extraction such as temperature and time may be the same conditions as extraction using an extraction solvent containing ethanol as a main component.
When the extraction solvent is ethanol, the liquid extract may be directly subjected to the following reaction, or when the extraction solvent is a mixed solvent of ethanol with water or the extraction solvent contains water, the liquid extract after reduction of the amount of water in the system to such an extent that at least the reaction proceeds may be subjected to the following reaction.
A manner for reduction of the amount of water may include concentration of the liquid extract.
The amount of water in this context may be less than 90% by weight, preferably less than 50% by weight, more preferably less than 10% by weight in the solution for esterification reaction in an embodiment.
When the extraction solvent is ethanol, it is not required to add a step of removing water from the liquid extract.
The obtained liquid extract is concentrated and esterification reaction is carried out with a catalyst under conditions such that the pressure is at or lower than a predetermined value. Therefore, it is preferable to carry out the reaction in a pressure resistance vessel or the like. The catalyst that can be used is described hereinafter.
The pressure during the reaction may be normal pressure to 1 MPa.
The reaction time may be 5 to 500 minutes, preferably 10 to 300 minutes and more preferably 10 to 180 minutes.
The temperature during the reaction may be 60°C to 150°C, preferably 80°C to 120°C and more preferably 100°C to 120°C. In order to ensure such a temperature, it is preferable to carry out the reaction under heating.
The amount of the catalyst used may be, when a solid acid is used, 5% to 400% by weight, preferably 10% to 300% by weight and more preferably 20% to 200% by weight relative to the wet weight of tobacco leaves.
When a liquid acid is used, the amount may be 0.001% to 10% by weight, preferably 0.01% to 8% by weight and more preferably 0.1% to 5% by weight relative to the wet weight of tobacco leaves.
The esterification reaction may be carried out while the reaction solution contains the catalyst or the catalyst may be, when the catalyst is a solid acid, removed from the reaction solution prior to esterification reaction. When the solid acid exemplified above is used, esterification reaction proceeds by bringing the catalyst into contact with the reaction solution thereby allowing proton exchange. Specifically, when the reaction is heated, esterification reaction proceeds even when the solid acid does not exist in the solution.
The solution obtained after esterification reaction of the liquid extract contains diethyl malate and one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate, and the solution directly or after removal of unnecessary substances such as the catalyst may serve as a treatment liquid containing the composition of the present invention.
The treatment liquid containing the composition of the present invention obtained through the above process may be added back to the extraction residue of the tobacco leaves. When the treatment liquid is added to another tobacco product such as shredded tobacco, the treatment liquid is subjected to isolation and purification to prepare the composition which is then added to a material of the tobacco product.
The conditions for the separation and purification in this context may be well-known distillation under reduced pressure or chromatography.
A method for producing a tobacco material containing tobacco leaves and the composition containing the ethyl ester compounds obtained by reacting ethanol with malic acid and one or more selected from levulinic acid, palmitic acid and citric acid contained in tobacco leaves without extraction may be a method in which a catalyst and ethanol are added to tobacco leaves to allow ethyl esterification reaction.
According to the method, a tobacco material may be prepared which contains tobacco leaves and a composition containing diethyl malate and one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate. In this case, the obtained tobacco material containing the composition and tobacco leaves may be directly used. The tobacco material containing the composition and tobacco leaves prepared according to the above method may be mixed with a material for tobacco product such as another tobacco leaves.
The conditions for the esterification in this context may be the same conditions as esterification of the above liquid extract.
The catalyst used for synthesis of the ethyl ester compounds may be a liquid acid or a solid acid.
The liquid acid preferably has an acid dissociation constant of 6 or less and more preferably less than 3.
Specific examples of the liquid acid include sulphuric acid, sulphurous acid, hydrochloric acid, hypochlorous acid, benzoic acid, formic acid, citric acid, malic acid, tartaric acid, valeric acid, isovaleric acid, butyric acid, malonic acid, glutamic acid, succinic acid, lactic acid, acetic acid, salicylic acid, oxalic acid, phosphoric acid and the like.
Examples of the solid acid include natural mineral, cation-exchange resins, immobilised acids, metal oxides, composite metal oxides, calcinated metal sulphates and the like.
A specific example of the solid acid preferably has a desorption ammonia amount of 10 µmol/g or more at a desorption peak in the temperature range of less than 500°C as measured by an ammonia TPD method described hereinafter.
The solid acid that can be used in the production method of the present invention more preferably has an ammonia desorption amount of 500 µmol/g or more at a desorption peak in the temperature range of less than 400°C as measured by the ammonia TPD method.
By using such a catalyst, ethyl ester compounds are efficiently produced.
Examples of the solid acid having the above characteristic include organic substances such as resins having acidic exchange groups (such as styrene resins) and inorganic carriers such as silica gel carrying acidic functional groups. Examples of the acidic exchange groups and acidic functional groups include a sulphonate group.
Specific solid acids include those indicated in the following table.

[Table 1]

Table 1

No.	Catalyst
1	Amberlyst 15DRY produced by Organo Corporation
2	Amberlyst 31 WET produced by Organo Corporation
3	Amberlyst 15JWET produced by Organo Corporation

In the ammonia TPD method, the solid acid is pretreated to remove water adsorbed thereon, ammonia is adsorbed thereon and then desorbed by increasing temperature. When the desorption amount is plotted relative to the temperature during desorption by temperature increase, the acid amount and the acid strength can be estimated from the extent of the desorption amount and the desorption temperature, respectively.
The measurement conditions are described below.

Analytical device: fully automated temperature programmed desorption spectrometer TPD-1-ATw produced by BEL Japan, Inc.
Sample amount: about 0.05 g
Temperature programmed desorption analysis: a target gas component is detected on a quadruple mass analyser.
Measurement range: 80°C to 800°C
Measurement atmosphere: He 50 mL/min
Fragment detected: m/z = 16

The details for temperature increase conditions and the like are shown in Fig. 2.
Altogether, embodiments of methods for producing the composition of the present invention and a tobacco material containing the composition and tobacco leaves may be (A) to (C) below. In the following embodiments, the conditions for extraction and esterification reaction are described above.

(A) A method for producing, including an extraction step of obtaining a liquid extract of tobacco leaves with ethanol and an esterification reaction step of adding a catalyst to the liquid extract obtained in the extraction step to carry out esterification reaction.
(B) A method for producing, including the step of obtaining a liquid extract of tobacco leaves with water or a solvent containing water and ethanol; the following step (1) or (2):
1. (1) the step of concentrating the liquid extract obtained in the extraction step to obtain a concentrate to which ethanol is added; or
2. (2) the step of adding ethanol to the liquid extract obtained in the extraction step;
and an esterification reaction step of adding a catalyst to any of the following (i) to (iv) followed by esterification reaction:
1. (i) the liquid extract obtained in the extraction step;
2. (ii) the concentrate obtained in the step (1);
3. (iii) the solution obtained after the step (1); or
4. (iv) the solution obtained after the step (2).
(C) A method for producing, including an esterification reaction step of carrying out esterification reaction of a material obtained by mixing tobacco leaves, ethanol and a catalyst.

In the method of the embodiment (A), a liquid extract is obtained from tobacco leaves with ethanol as an extraction solvent and the catalyst is added to the liquid extract to carry out esterification reaction.
In the method of the embodiment (B), a liquid extract is obtained from tobacco leaves with water or water and ethanol as an extraction solvent; the liquid extract is concentrated to obtain a concentrate to which ethanol is added (the step (1)) or ethanol is added to the liquid extract without concentration (the step (2)); and the catalyst is added to the solution or concentrate obtained in either of the steps to carry out esterification reaction.
In the method of the embodiment (C), apart from (A) or (B), ethanol and the catalyst are added to tobacco leaves, which have not been subjected to extraction, and esterification reaction is carried out.
In any of the embodiments (A) to (C) wherein the catalyst used is the solid acid, the catalyst may be removed from the solution by filtration or the like operation prior to the esterification reaction because, as described above, as far as proton exchange is carried out by once bringing the reaction solution into contact with the solid acid, the reaction proceeds even when the catalyst does not exist in the reaction solution. When the solid acid is removed, the catalyst may be reused.
Tobacco leaves which may be used for preparation of the composition of the present invention or a tobacco material containing the composition may include shredded tobacco (hereinafter also referred to as shredded leaf tobacco) used for cigarettes.
When tobacco leaves used are shredded tobacco, the shredded tobacco may be of any variety. For example, stemmed tobacco leaves and stems of Flue-Cured tobacco, Burley and Oriental, and a regenerated sheet formed with the above material may be used. Shredded tobacco generally means one that is ready to be used for production of a tobacco product. Shredded tobacco may have any well-known size of shredded leaf pieces without limitation.
In the present invention, tobacco leaves used for extraction of malic acid, levulinic acid, palmitic acid and citric acid may also be the same as above.
When a tobacco product is a cigarette, shredded tobacco in the cigarette may have any well-known size of leaves. The configuration of the cigarette as a tobacco product is not particularly limited and may have any well-known aspects.
The composition of the present invention may contain other additives in the range that does not impair the effect of the present invention. Examples of such an additive include a fragrance and a humectant.
In preferable embodiments, the composition of the present invention may be added to tobacco leaves for preparation of a tobacco product or a tobacco material including the composition and tobacco leaves may be directly used.
The tobacco product may preferably be a smoking article. Namely, it is preferable that the composition of the present invention, and the tobacco material including the composition and tobacco leaves, are used for a smoking article among tobacco products, respectively.
The composition of the present invention, and the tobacco material including the composition and tobacco leaves, may also be used for an oral tobacco product or an electronic tobacco, respectively.
Examples of the smoking article include cigarettes, cigars and cigarillos.
When the composition of the present invention is added to tobacco leaves for production of a tobacco product, the composition of the present invention is added to tobacco leaves for preparation of the tobacco product.
When a tobacco material including the composition of the present invention and tobacco leaves is directly used, the tobacco leaves used for the tobacco product are used during preparation of the composition for the tobacco material. In this case, the tobacco material including the composition of the present invention and tobacco leaves may be directly used as an ingredient for the tobacco product.
When the composition per se is used as a tobacco material, the ingredient derived from tobacco leaves such as shredded tobacco in the composition may be 80% to 99.99% by weight relative to the total amount of the composition in terms of the dry weight in an embodiment.
When the composition of the present invention is added to tobacco leaves, the amount of the composition added is not particularly limited. In an embodiment, the composition may be added so that diethyl malate is 5% to 95% by weight relative to the total weight of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the ingredient for a tobacco product formed with tobacco leaves to which the composition has been added.
In the above embodiment, it is more preferable that the content of diethyl malate is 20% to 60% by weight relative to the total weight of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
When the composition of the present invention is added to tobacco leaves at the amount described above, the effect of reducing the smell of sidestream smoke may be preferably obtained.
It is also preferable to add the composition of the present invention so that the content of diethyl malate is 0.0005% to 1% by weight relative to the wet weight of the ingredient for a tobacco product formed with tobacco leaves to which the composition has been added.
Meanwhile, when a tobacco material per se is used which includes the composition of the present invention and tobacco leaves, diethyl malate is 5% to 95% by weight relative to the total weight of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the tobacco material in an embodiment.
In the above embodiment, it is more preferable that the content of diethyl malate is 20% to 60% by weight relative to the total weight of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
It is also preferable, in the embodiment, that the content of diethyl malate is 0.0005% to 1% by weight relative to the wet weight of tobacco leaves.
When the composition of the present invention or the tobacco material contains diethyl malate at the above content, the effect of reducing the smell of sidestream smoke may be preferably obtained.
In any of the above embodiments, the amount of diethyl malate is preferably 5% to 95% by weight and more preferably 20% to 60% by weight relative to the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate in the composition of the present invention or the tobacco material. Examples
The present invention is more specifically described by way of Examples which do not limit the present invention within the scope of the invention.

<Example 1> Ethyl esterification reaction using a tobacco liquid extract obtained with a solid acid catalyst

It is normally carried out to use a liquid acid such as sulphuric acid or a solid acid which is a resin carrying an acidic functional group as a catalyst for esterification reaction. Particularly when the reactant/product is liquid, a solid acid which can be easily separated is useful. Therefore, the solid acid was used for synthesis of ethyl ester compounds from an ethanol liquid extract of tobacco leaves.

Effect of the type of catalysts on the reaction

Ethanol was added to shredded Japanese Flue-Cured tobacco at a solid-liquid ratio of 1 g-wet tobacco : 10 ml, extraction was carried out while shaking in a water bath at 60°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. After concentrating the liquid extract to a predetermined concentration, the liquid extract was heated in a pressure resistance vessel together with a catalyst at 120°C for 1 hour. Five different catalysts indicated in Table 2 were used. The catalysts purchased were used without pretreatment and the amount added was 50% by weight relative to the wet weight of tobacco.

Analysis of the treatment liquid

As a preliminary examination, a qualitative analysis was carried out by GC-MS with the column, DB-WAX (J&W 122-7032) produced by Agilent Technologies. As a result, it was found that ethyl levulinate, diethyl malate, ethyl palmitate and triethyl citrate were produced at high amounts in the treatment liquid of Example 1. In the present test system, GC-FID analysis using the same column was carried out for the above four ethyl ester compounds which were quantified by an internal reference method from the peak area. The results are shown in Fig. 1.

[Table 2]

Table 2: Catalysts used

No.	Catalyst	Functional group	Carrier	Specific surface area* (m²/g-dry)	Average pore diameter* (nm)
1	Commercial product solid acid a	-SO₃ H	Styrene resin		45	24
2	Commercial product solid acid b	-SO₃H	Styrene resin	-	-
3	Commercial product solid acid c	-SO₃H	Silica gel	440	6
4	Commercial product solid acid d	-SO₃H	Silica gel	380	6
5	Commercial product solid acid e	-SO₃ H	Styrene resin		50	24

* The specific surface area and the average pore diameter are values indicated in catalogues. The specific surface area and the average pore diameter were not available from catalogue for the commercial product solid acid b.

From Fig. 1, it was confirmed that the reaction progressed with commercially available solid acids. The present results are merely an example and optimal reaction and pretreatment conditions may be selected according to the desired amount and composition of ethyl esters or facilities to be used.

Characterisation of the catalysts used

The acid strength and acid amount of the catalysts used in Example 1 were estimated by the ammonia TPD method. The method is a way to examine the amount and strength of the acid site, in which adsorbed water is removed by pretreatment and then ammonia is adsorbed and desorbed by increasing temperature. When the desorption amount is plotted relative to the temperature during desorption by temperature increase, the acid amount and acid strength can be estimated from the extent of the desorption amount and the desorption temperature, respectively.
The measurement conditions are as follows (Fig. 2 also shows the temperature increase conditions and the like):

Analytical device: fully automated temperature programmed desorption spectrometer TPD-1-ATw produced by BEL Japan, Inc.
Sample amount: about 0.05 g
Temperature programmed desorption analysis: a target gas component was detected on a quadruple mass analyser.
Measurement range: 80°C to 800°C
Measurement atmosphere: He 50 mL/min
Fragment detected: m/z = 16

The results of the measurement are shown in Table 3. From the results indicated in Table 3, it was found that the catalysts with which the esterification reaction progressed in the method of Example 1 had the desorption amount of 10 µmol/g or more at desorption peaks in a temperature range of at or less than 500°C in the ammonia TPD method.

[Table 3]

Table 3: Results of ammonia TPD analysis of solid acids

1 Commercial product solid acid a
	306	415	463	485
	1600	460	850	540
2 Commercial product solid acid b
	188	314	382
	13	98	120
3 Commercial product solid acid c
	229	515
	530	98
4 Commercial product solid acid d
	228	507
	500	93
5 Commercial product solid acid e
	315	382	434
	1200	600	270
Upper column: peak temperature [°C], lower column: desorption amount [µ mol/g]

<Example 2> Reaction of ethanol liquid extract

Ethanol was added to shredded leaf tobacco at a solid-liquid ratio of 1 g-wet tobacco: 10 ml, extraction was carried out while shaking in a water bath at 60°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. After concentrating the liquid extract to a predetermined concentration, the liquid extract was heated in a pressure resistance vessel together with 50% by weight of the commercial product solid acid c relative to the wet weight of tobacco at 120°C for 3 hours.

Comparative Example 1: Comparison to Patent Document 1: Reaction of hydrophobic fraction in a methanol liquid extract

Methanol was added to shredded leaf tobacco at a solid-liquid ratio of 1 g-wet tobacco: 5 ml, extraction was carried out while shaking in a water bath at 50°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. Methanol was volatilized from the liquid extract, equal amounts of hexane and water were added and the mixture was vigorously shaken. Only the organic phase was recovered from which hexane was volatilized, and then dissolved in ethanol. The solution was subjected to the reaction under the same conditions as in Example 1.

Composition of the treatment liquid

Fig. 3 shows the ethyl ester content in the treatment liquids of Example 2 and Comparative Example 1. It was confirmed that in Example 2, the amounts of diethyl malate and ethyl levulinate produced were particularly high, which otherwise were not generated in Comparative Example 1, and that ethyl palmitate was commonly generated in Example 1 and Comparative Example 1 was at a similar level.
It is believed that the above difference occured because extracted organic acids with high polarity such as malic acid and citric acid were partitioned into an aqueous phase by separation with hexane/water without being involved in the reaction in Comparative Example 1, and thus were not generated. Meanwhile, the ester of levulinic acid which was detected in Example 1 generates by reaction of carbohydrates such as saccharides and starches with an alcohol (Non-Patent Document 1). Therefore, the ester of levulinic acid was not generated in Comparative Example 1 either because the extracted carbohydrates were partitioned into an aqueous phase by separation without being involved in the reaction. As the reaction was carried out under the same conditions in Example 1 and Comparative Example 1, it can be understood that the qualitative and quantitative difference of the products results from the manners of preparation of the reaction solutions including extraction and separation.

Sensory evaluation using the treatment liquid

The sensory evaluation of the smell of sidestream smoke was carried out by burning cigarettes in a room and comparing and evaluating the smell in the room after a predetermined period. The evaluation was carried out by paired comparison and about 30 subjects were included in a panel per pair of evaluation. The panel chose which room between the two smelled more strongly of tobacco.

Sensory evaluation result 1: Change before and after treatment with Example 2

Treated tobacco: Japanese Flue-Cured tobacco
Material product: paper tubes for a commercially available cigarette product
Treated sample: cigarettes prepared with paper tubes of a commercially available cigarette product by carrying out the treatment of Example 1 (120°C, 3 hours, catalyst amount added: 50% by weight per wet weight of tobacco) on blended and shredded Japanese Flue-Cured tobacco to obtain a treatment liquid (composition) which was then added back to the original extraction residue.
Untreated sample: cigarettes prepared with blended and shredded Japanese Flue-Cured tobacco and paper tubes of a commercially available cigarette product.

Fig. 4 shows the results of the choice between the two by the evaluation panel as to which had a stronger tobacco smell. According to Fig. 4, significantly more people answered that the treated cigarettes had less tobacco smell. Thus, the effect of reducing the smell of tobacco sidestream smoke could be confirmed.

Sensory evaluation result 2: effect of addition of the treatment product of Example 2

Treated tobacco: Flue-Cured tobacco stems
Material product: paper tubes for a commercially available cigarette product
Test sample: cigarettes obtained by isolating a composition containing ester compounds by distillation under reduced pressure and solid phase extraction of the treatment liquid prepared according to the treatment of Example 1 (120°C, 3 hours, catalyst amount added: 50% by weight per wet weight of tobacco) on blended and shredded foreign Flue-Cured tobacco stems and then adding the composition to shredded tobacco (shredded tobacco A) from which fragrance was volatilized by opening the commercially available cigarette product. The amount of the composition added was such that the total ester amount was 0.14% to 0.95% by weight relative to the amount of shredded tobacco A.
Reference sample: cigarettes prepared with shredded tobacco A.

Fig. 5 shows the results of the choice between the two by the evaluation panel as to which had a stronger tobacco smell. The numerical values on the vertical axis in Fig. 5 represents the weight proportion of the total ester amount relative to the amount of shredded tobacco A in each sample. Significantly more people answered that the test sample cigarettes had less tobacco smell. Thus, even by adding the composition of the present invention to separate shredded tobacco, the effect of reducing the smell of tobacco sidestream smoke could be confirmed.

Sensory evaluation result 3: Comparison to the background art (Patent Document 1)

Treated tobacco: Japanese Flue-Cured tobacco
Material product: paper tubes for a commercially available cigarette product

Example 1: cigarettes prepared by adding to shredded tobacco A a composition obtained by isolating ester compounds by distillation under reduced pressure and solid phase extraction of the treatment liquid of Example 1 which is the method of the present invention (treated material was Japanese Flue-Cured tobacco, reaction conditions were 120°C and 3 hours, the amount of the catalyst added was 50% by weight per wet weight of tobacco). The weight ratio of (tobacco used for preparation of the treatment liquid) : (shredded tobacco A to which the treatment liquid was added) was 1:2.
Comparative Example 1: cigarettes prepared in the same manner as in the above except that the treatment product added was prepared according to the manner in Comparative Example 1.
As shown in Fig. 6, significantly more people answered that cigarettes prepared according to the manner (Comparative Example 1) disclosed in the background art (Patent Document 1) had stronger tobacco smell. Therefore, it was confirmed that the composition of the present invention was superior in the effect of reducing the tobacco smell.

Sensory evaluation result 4: Contribution of each component

The ester compounds generated by the method of the present invention were examined for contribution to the effect of reducing smell by adding reagents of the respective compounds to shredded tobacco.

Material product: paper tubes for a commercially available cigarette product
Test product: cigarettes prepared with paper tubes for a commercially available cigarette product and test shredded tobacco obtained by dissolving each reagent in ethanol and spraying the solution to shredded tobacco A at 0.1% or 1% relative to the wet weight of shredded tobacco A followed by blending and drying.
Reference product: cigarettes prepared with shredded tobacco A to which ethanol at the same amount as the test product was sprayed.

According to Fig. 7, at 1% addition, triethyl citrate, ethyl palmitate and ethyl levulinate showed the effect of reducing tobacco smell. Meanwhile, cigarettes to which diethyl malate was added had an increased selected proportion of tobacco smell. At 0.1% addition, the results showed that all components reduced tobacco smell or did not cause any change.

Sensory evaluation result 5: mixing of components

By focusing on ethyl palmitate, triethyl citrate and diethyl malate obtained through the above treatment, the effect of the added amount and mixing was examined.

Material product: paper tubes for a commercially available cigarette product
Test product: cigarettes prepared with test shredded tobacco obtained by dissolving each reagent to ethanol so as to be the amount added indicated in Table 4 and spraying the solution to the wet weight of shredded tobacco A followed by blending and drying.
Reference product: cigarettes prepared with shredded tobacco A to which ethanol at the same amount as the test product was sprayed.

[Table 4]

Table 4: Test conditions

No.	Amount added [wt%]
	Ethyl palmitate	Diethyl malate	Total
1	0	1	1
2	1	0	1
3	0.425	0.475	0.9

	Triethyl citrate	Diethyl malate	Total
4	1	0	1
5	0.425	0.475	0.9

As shown in Fig. 8-1 and Fig. 8-2, it was suggested that ethyl palmitate and triethyl citrate when respectively mixed with diethyl malate showed a stronger effect of reducing smell of tobacco sidestream smoke than when added respectively alone.
From Fig. 8-1 and Fig. 8-2, some of Examples above are again indicated by focusing on the abundance ratio of the components. The numbers on the vertical axis in the figure correspond to the sample number in Table 4. A selected proportion for test product in the table means the number of participants who found that the test product had a stronger smell out of all participants.

[Table 5]

Table 5: Table corresponding to Fig. 9

Test product	Ester content relative to the wet weight of the test product [%]						Sensory evaluation result: Tobacco smell strength by choice between the two
Test product	Ethyl levulinate	Diethyl malate	Ethyl palmitate	Triethyl citrate	Total	Diethyl malate/all esters	Test product (no. of people)	Reference product (no. of people)	Selected proportion for Test product [-]
Sensory evaluation result (untreated material)	0.816	0.297	0.153	0.014	1.279	23.248	7	23	0.23
Sensory evaluation result 2-0.71%	0.328	0.287	0.060	0.038	0.713	40.203	6	24	0.20
Sensory evaluation result 5-No. 1	0.000	1.000	0.000	0.000	1.000	100.000	19	11	0.63
Sensory evaluation result 5-No. 2	0.000	0.000	1.000	0.000	1.000	0.000	10	20	0.33
Sensory evaluation result 5-No. 3	0.000	0.475	0.425	0.000	0.900	52.778	7	22	0.24
Sensory evaluation result 5-No. 4	0.000	0.000	0.000	1.000	1.000	0.000	12	18	0.40
Sensory evaluation result 5-No. 5	0.000	0.475	0.000	0.425	0.900	52.778	11	18	0.38

Fig. 9 shows the proportion of diethyl malate in the total ester amount and the selected proportion for tobacco smell by choice between the two in Table 5. The value on the vertical axis in Fig. 9 of less than 0.5 means that the proportion of the people was high who found that the test product (to which ethyl ester compounds were added) had less smell of tobacco sidestream smoke than the reference product (to which ethyl ester compounds were not added) .
Therefore, it was estimated that by mixing diethyl malate at a certain proportion, the effect of reducing smell is more strongly exhibited and diethyl malate obtained from malic acid contained in tobacco and that isolated as a reagent have the same effect.
Methods for increasing the amount of ester compounds produced and methods for conveniently producing the same are hereinafter described.

In Examples 1 and 2, esterification reaction was carried out by allowing transfer of organic acids in tobacco leaves to a liquid phase by extraction with ethanol and heating the liquid extract under acidic conditions. Ethanol used in this context is an extraction solvent of organic acids and is subjected to the esterification reaction.
The inventor thought that the yield of ethyl ester compounds produced may be increased by using a solvent having higher solubility for organic acids for extraction before the reaction. Therefore, the inventor also formulated the step in which water is used as an extraction solvent. Further, the inventor also formulated the step in which the catalyst per se is not heated and the step in which water is not completely volatilized before the reaction in view of easy recycling of the catalyst and reduction of process energy.

<Example 3> Water extraction step 1

Water was added to shredded leaf tobacco at a solid-liquid ratio of 1 g-wet tobacco: 10 ml, extraction was carried out while shaking in a water bath at 60°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. After water in the liquid extract was volatilized under reduced pressure, the residue was dissolved in ethanol to prepare an ethanol solution of tobacco water extract at a predetermined concentration. The reaction conditions were the same as in Example 1, which were 120°C and 3 hours, and the amount of the catalyst added was 100% by weight per wet weight of tobacco.

<Example 4> Water extraction step 2

Water was added to shredded leaf tobacco at a solid-liquid ratio of 1 g-wet tobacco : 10 ml, extraction was carried out while shaking in a water bath at 60°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. To the water liquid extract was added 166% by weight of the catalyst per wet weight of tobacco and was shaken to carry out proton exchange. The catalyst was separated and removed by filtration and water was volatilized under reduced pressure to obtain a proton-donated tobacco water extract. The extract was dissolved in ethanol so as to attain a predetermined concentration and esterification reaction was carried out by heating at 120°C for 3 hours in a pressure resistance vessel.

<Example 5> Water extraction step 3

Water was added to shredded leaf tobacco at a solid-liquid ratio of 1 g-wet tobacco : 10 ml, extraction was carried out while shaking in a water bath at 60°C for 1 hour and the liquid extract was separated from the extraction residue using a non-woven fabric. To the water liquid extract was added 166% by weight of the catalyst per wet weight of tobacco and was shaken to carry out proton exchange. The catalyst was separated and removed by filtration and water was concentrated up to a predetermined concentration to obtain a tobacco water extract. The equivalent amount of ethanol to the water extract on the volume basis was added and esterification reaction was carried out by heating at 120°C for 3 hours in a pressure resistance vessel.
The results in Examples 3 to 5 are shown in Table 6 and Fig. 10. As shown in Fig. 10, it was indicated that in the solutions extracted with water, the same reaction progressed as in the ethanol extraction above. Particularly in Example 4, diethyl malate was produced at about 8 times or more compared to Example 2, resulting in an improvement of the yield. It was believed that in Example 3, a reduction in the reaction rate due to an increase of contaminants more strongly affected than an increase in the amount of organic acids extracted with water. In Example 5, although the yield was decreased due to the reaction inhibition by water, it was possible to produce diethyl malate and ethyl palmitate even with a reduction of ethanol to a half amount.

[Table 6]

Table 6

	Example 3	Example 4	Example 5
Amount of catalyst	100%	166%	166%
Ethyl levulinate	0.5895	0.2706	0.0000
Diethyl malate	0.2494	2.5734	0.1641
Ethyl palmitate	0.0000	0.0000	0.0008
Triethyl citrate	0.0000	0.0447	0.0000

<Example 6> One stage process using a small amount of solvent

It was examined whether or not the reaction proceeds only by mixing tobacco leaves, a small amount of ethanol and the catalyst and heating without undergoing the extraction/separation step as described above.
About 10 ml of 0.05 g/ml citric acid-ethanol solution was added to 5 g (wet weight) of tobacco and subjected to the reaction by heating in a pressure resistance vessel. The heating conditions were 120°C and 3 hours.
A solution obtained by dispersing the solution containing tobacco leaves after the reaction in a predetermined amount of ethanol and filtered through a 0.45 µm filter was subjected to GC-MS analysis under the above conditions to obtain qualitative information of the products.
The upper panel and the lower panel of Fig. 11 show GC charts of the treatment product of Example 6 and the standard reagents, respectively. From Fig. 11, production of diethyl malate and ethyl palmitate was observed under the current conditions. Trace amounts of ethyl levulinate and triethyl citrate were observed. As the amount of the ethyl ester of citric acid was very low, it was estimated that citric acid added served mainly as a catalyst.
Citric acid has the first dissociation constant of 3.09 and is classified as a weak acid. It was demonstrated that in the method of the present invention, the reaction sufficiently proceeds even with a small amount of a weak acid.

[Industrial Applicability]

The composition of the present invention has the effect of reducing the smell of tobacco sidestream smoke while smoking a tobacco product when the composition is added to an ingredient for a tobacco product such as shredded tobacco or the composition is used with tobacco leaves per se. The present invention also provides a method for conveniently preparing the composition.

Claims

A composition comprising:
diethyl malate; and

one or more selected from ethyl levulinate, ethyl palmitate and triethyl citrate.
The composition according to claim 1, which is for a tobacco product.
The composition according to claim 1 or 2, wherein the amount of diethyl malate is at 5% to 95% by weight relative to the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
The composition according to any one of claims 1 to 3, wherein the amount of diethyl malate is at 20% to 60% by weight relative to the total amount of diethyl malate, ethyl levulinate, ethyl palmitate and triethyl citrate.
A tobacco material comprising tobacco leaves and the composition according to any one of claims 1 to 4.
A method for producing a composition containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate, the method comprising an extraction step of obtaining a liquid extract of tobacco leaves by using ethanol and an esterification reaction step of adding a catalyst to the liquid extract obtained in the extraction step to carry out esterification reaction.
The method according to claim 6, wherein the catalyst is a solid acid, and the method comprises a step of removing the added solid acid catalyst prior to esterification reaction.
A method for producing a composition containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate,
the method comprising a step of obtaining a liquid extract of tobacco leaves by using water or a solvent containing water and ethanol, and a following step (1) or (2):
(1) a step of concentrating the liquid extract obtained in the extraction step in order to obtain a concentrate, and then adding ethanol to the concentrate; or

(2) a step of adding ethanol to the liquid extract obtained in the extraction step; and
an esterification reaction step of adding a catalyst to any of the following (i) to (iv), followed by esterification reaction:
(i) a liquid extract obtained in the extraction step;

(ii) a concentrate obtained in the step (1);

(iii) a solution obtained after the step (1); or

(iv) a solution obtained after the step (2).
The method according to claim 8, wherein the catalyst is a solid acid, and the method comprises a step of removing an added solid acid catalyst prior to esterification reaction.
A method for producing a tobacco material containing diethyl malate and one or more from ethyl levulinate, ethyl palmitate and triethyl citrate,
the method comprising an esterification reaction step of carrying out esterification reaction of a material obtained by mixing tobacco leaves, ethanol and a catalyst.
The method according to claim 10, wherein the catalyst is a solid acid, and the method comprises a step of removing a solid acid catalyst prior to esterification reaction.
The method according to any one of claims 6 to 11, wherein the esterification reaction step is carried out for 5 to 500 minutes at a temperature of 60°C to 150°C.
The method according to any one of claims 6 to 11, wherein the catalyst is a solid acid having a desorption amount of 10 µmol/g or more at a desorption peak at less than 500°C in an ammonia TPD method.
The method according to any one of claims 6, 8, 10 and 12, wherein the catalyst is a liquid acid.