HK1190284B - Method for producing fragrance-containing sheet for smoking article, fragrance-containing sheet for smoking article produced by method, and smoking article containing same - Google Patents

Description

Method for producing a flavored sheet for smoking articles, flavored sheet for smoking articles produced by the method, and smoking articles containing the same

Technical Field

The present invention relates to a method for producing a flavor-containing sheet for smoking articles, the flavor-containing sheet for smoking articles produced by the method, and a smoking article comprising the sheet.

Background Art

When volatile flavoring components such as menthol are added to cut tobacco in a solution state, the flavoring components dissipate during long-term storage, resulting in a lack of sustained flavoring effect. Various reports have been made to address this issue.

Patent Documents 1 and 2 disclose methods in which flavoring ingredients are coated with natural polysaccharides and placed in the filter portion of a cigarette to suppress the volatilization and dissipation of the flavoring ingredients. The flavoring ingredients are then squeezed and destroyed during smoking to release the flavoring ingredients. Furthermore, Patent Document 3 discloses a method in which flavoring ingredients are coated with a water-soluble matrix, such as dextrin, and placed in the filter portion of a cigarette to suppress the volatilization and dissipation of the flavoring ingredients. The water-soluble matrix is dissolved by the mainstream smoke during smoking to release the flavoring ingredients. Therefore, when flavoring ingredients are placed in the filter portion, which is the non-combustion portion of the cigarette, smoking requires squeezing the filter portion or dissolving the water-soluble matrix by the moisture in the mainstream smoke to release the flavoring ingredients. Consequently, there is a time lag before the flavoring ingredients are perceived.

On the other hand, Patent Documents 4 to 6 report examples in which flavoring components are arranged in shredded tobacco serving as a burning portion or in the wrapping paper that wraps the shredded tobacco.

Patent Document 4 discloses a method for applying a flavoring material, obtained by incorporating flavoring components into the three-dimensional network structure of glucan molecules, to the wrapping paper of a tobacco filling material. The cigarettes of Patent Document 4 exhibit excellent flavor retention because the flavoring components are incorporated into the three-dimensional network structure of glucan molecules, where they are fixed and retained. However, since the flavoring components are present in relatively small amounts (less than 20% by weight) within the glucan molecules, the amount of flavoring material added to the cigarettes increases for flavoring components such as menthol that require a relatively large addition.

Patent Document 5 discloses a method for producing a "stabilized fragrance material stable up to 180°C" by mixing a liquid fragrance and a carrageenan sol and adding the mixture dropwise to an ionic solution (a solution containing potassium ions) to form a granular gel. The granular gel is then dried in air. However, the method in Patent Document 5 requires a long time and large equipment to prepare a large amount of raw materials because the granular gel is dried in air. Furthermore, this method involves the addition of metal ions (gelation accelerators) to promote gelation.

Patent Document 6 reports a method in which a slurry containing flavoring ingredients such as menthol and polysaccharides is dried to create a sheet in which the flavoring ingredients are coated with a polysaccharide gel. This sheet is then cut and added to shredded tobacco. In this report, drying the slurry at 40°C takes one week.

As described above, various technologies for suppressing the volatilization of fragrance components have been reported, and efforts have been made to produce fragrance raw materials with improved storage and fragrance retention properties by simple methods.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 64-27461

Patent Document 2: Japanese Patent Application Laid-Open No. 4-75578

Patent Document 3: International Publication No. 2009/157240 Pamphlet

Patent Document 4: Japanese Patent Application Laid-Open No. 9-28366

Patent Document 5: Japanese Patent Publication No. 11-509566

Patent Document 6: International Publication No. 2009/142159 Pamphlet

Summary of the Invention

Problems to be solved by the invention

The object of the present invention is to provide a method for producing a flavoring sheet for smoking articles in a short time, which has a high flavoring content, a high flavoring preparation yield, and a high storage and flavor retention property when combined with smoking articles; and a flavoring sheet for smoking articles which has a high storage and flavor retention property when combined with smoking articles and can be produced in a short time.

Methods used to solve problems

The present inventors conducted research to solve this problem and found that when a raw material slurry containing polysaccharides, fragrances, and emulsifiers is heated and dried to prepare a fragrance-containing sheet, if carrageenan or gellan gum is used as the polysaccharide and the slurry is temporarily cooled before heating and drying before drying, a sheet with a high fragrance content and a high fragrance production yield can be produced even when a high drying temperature is used. The sheet also maintains a high fragrance content even after storage, thereby completing the present invention.

That is, according to one aspect of the present invention, a method for manufacturing a flavored sheet for smoking articles can be provided, which is characterized in that it includes the following steps: a step of spreading the following raw material slurry in a sol state at 60 to 90°C on a base material, wherein the raw material slurry contains: a polysaccharide containing at least one of carrageenan and gellan gum, a flavor, an emulsifier, and 70 to 95 weight % of water, and the content of the flavor based on the polysaccharide is in the range of 100 to 1000 weight %; a step of cooling the spread raw material slurry to a sample temperature of 0 to 40°C to gel it; and a heating and drying step, which includes heating the gelled raw material and drying it at a sample temperature of 70 to 100°C.

According to a preferred embodiment, the emulsifier is 0.5 to 5% by weight of lecithin relative to the polysaccharide. Alternatively, according to a preferred embodiment, the emulsifier is an ester selected from glycerol fatty acid esters, polyglycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, and sucrose fatty acid esters.

According to a preferred embodiment, the concentration of the polysaccharide in the raw material slurry is 2 to 5% by weight.

According to a preferred embodiment, the flavor is menthol. According to a further preferred embodiment, the content of menthol is in the range of 250 to 500% by weight relative to the weight of the polysaccharide.

In addition, according to another aspect of the present invention, a flavor-containing sheet for smoking articles manufactured by the method can be provided.

According to another aspect of the present invention, there is provided a smoking article comprising shredded tobacco, wherein the shredded tobacco is blended with cut pieces of the flavor-containing sheet for smoking articles.

Effects of the Invention

The method for producing a flavored sheet for smoking articles according to the present invention allows for the production of a flavored sheet for smoking articles in a short time, with a high flavor content, a high flavor yield, and excellent shelf-storage flavor retention when incorporated into smoking articles. Furthermore, the flavored sheet for smoking articles according to the present invention exhibits excellent shelf-storage flavor retention when incorporated into cigarettes and can be produced in a short time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the menthol content of a menthol-containing sheet after storage.

FIG. 2A is a graph showing changes in viscosity of a gellan gum aqueous solution as the temperature decreases.

FIG. 2B is a graph showing changes in viscosity of a gellan gum aqueous solution as the temperature increases.

FIG. 3A is a graph showing the temperature of the sample of sample number 1 during the heat drying step.

FIG. 3B is a graph showing the temperature of the sample of sample number 2 during the heat drying step.

FIG3C is a graph showing the temperature of the sample of sample number 3 during the heat drying step.

FIG3D is a graph showing the temperature of the sample of sample number 4 during the heat drying step.

FIG3E is a graph showing the temperature of the sample of sample number 5 during the heat drying step.

FIG3F is a graph showing the temperature of the sample of sample number 6 during the heat drying step.

FIG3G is a graph showing the temperature of the sample of sample number 7 during the heating and drying step.

FIG. 4A is a graph showing the effect of cooling on the menthol content of a menthol-containing sheet (comparative example) after storage.

FIG. 4B is a graph showing the effect of cooling on the menthol content of a menthol-containing sheet (an example of the present invention) after storage.

FIG. 5 is a graph showing the relationship between the cooling temperature and the menthol content of the menthol-containing sheet.

FIG. 6 is a graph showing the relationship between the moisture content of a menthol-containing sheet and the menthol flavor retention rate.

FIG7A is a graph showing changes in viscosity of a carrageenan aqueous solution as the temperature decreases.

FIG7B is a graph showing changes in viscosity of a carrageenan aqueous solution as the temperature increases.

FIG7C is a graph showing the temperature of a sample of a raw material slurry containing carrageenan as a polysaccharide during the heat drying step.

FIG7D is a graph showing the menthol content of menthol-containing sheets prepared using a raw material slurry containing carrageenan as a polysaccharide after storage.

FIG7E is a graph showing the temperature of a sample of a raw material slurry containing gellan gum as a polysaccharide during the heating and drying step.

FIG7F is a graph showing the menthol content of menthol-containing sheets prepared using a raw material slurry containing gellan gum as a polysaccharide after storage.

FIG7G is a graph showing changes in viscosity of a pectin aqueous solution as the temperature decreases.

FIG7H is a graph showing changes in viscosity of a pectin aqueous solution as the temperature increases.

FIG7I is a graph showing the temperature of a sample of a raw material slurry containing pectin as a polysaccharide during a heat drying step.

FIG7J is a graph showing the menthol content of menthol-containing sheets prepared using a raw material slurry containing pectin as a polysaccharide after storage.

FIG. 7K is a graph showing changes in viscosity of a konjac glucomannan aqueous solution as the temperature decreases.

FIG. 7L is a graph showing changes in viscosity of a konjac glucomannan aqueous solution as the temperature increases.

FIG7M is a graph showing the temperature of a sample of a raw material slurry containing konjac glucomannan as a polysaccharide during a heat drying step.

FIG. 7N is a graph showing the menthol content of menthol-containing sheets prepared using a raw material slurry containing konjac glucomannan as a polysaccharide after storage.

FIG8A is a graph showing changes in viscosity of carrageenan aqueous solutions of various concentrations as the temperature decreases.

FIG8B is a graph showing changes in viscosity of carrageenan aqueous solutions of various concentrations as the temperature increases.

FIG8C is a graph showing the menthol content of menthol-containing sheets prepared using raw material slurries containing various carrageenan concentrations after storage.

FIG8D is a graph showing changes in viscosity of gellan gum aqueous solutions of various concentrations as the temperature decreases.

FIG8E is a graph showing changes in viscosity of gellan gum aqueous solutions of various concentrations as the temperature increases.

FIG8F is a graph showing the menthol content of menthol-containing sheets prepared using raw material slurries containing various concentrations of gellan gum after storage.

FIG. 9A is a graph showing the menthol content of menthol-containing sheets prepared using raw material slurries containing carrageenan and menthol at various ratios after storage.

FIG9B is a graph showing the menthol flavor retention rate of menthol-containing sheets prepared using raw material slurries containing carrageenan and menthol at various ratios.

FIG9C is a graph showing the menthol yield of menthol-containing sheets produced using raw material slurries containing carrageenan and menthol at various ratios.

FIG9D is a graph showing the relationship between the menthol blending ratio and the menthol content of a menthol-containing sheet (when the polysaccharide is carrageenan).

FIG9E is a graph showing the relationship between the menthol blending ratio and the menthol yield of a menthol-containing sheet (when the polysaccharide is carrageenan).

FIG. 9F is a graph showing the menthol content of menthol-containing sheets prepared using raw material slurries containing gellan gum and menthol at various ratios after storage.

FIG9G is a graph showing the menthol flavor retention rate of menthol-containing sheets prepared using raw material slurries containing gellan gum and menthol at various ratios.

FIG9H is a graph showing the menthol yield of menthol-containing sheets prepared using raw material slurries containing gellan gum and menthol at various ratios.

FIG9I is a graph showing the relationship between the menthol blending ratio and the menthol content of a menthol-containing sheet (when the polysaccharide is gellan gum).

FIG9J is a graph showing the relationship between the menthol blending ratio and the menthol yield of a menthol-containing sheet (in the case where the polysaccharide is gellan gum).

10A is a graph showing the menthol content of menthol-containing sheets after storage, which were prepared using raw material slurries containing lecithin in various blending amounts (weight ratio relative to the polysaccharide) (when the polysaccharide was carrageenan).

FIG. 10B is a graph showing the relationship between the amount of lecithin added and the menthol content of a menthol-containing sheet (when the polysaccharide is carrageenan).

10C is a graph showing the menthol content of menthol-containing sheets after storage, which were prepared using raw material slurries containing lecithin in various blending amounts (weight ratio relative to the polysaccharide) (when the polysaccharide was gellan gum).

FIG10D is a graph showing the relationship between the amount of lecithin added and the menthol content of a menthol-containing sheet (when the polysaccharide is gellan gum).

FIG. 11A is a graph showing the effect of the type of emulsifier on the menthol content of a menthol-containing sheet (when the polysaccharide is carrageenan).

FIG. 11B is a graph showing the effect of the type of emulsifier on the menthol content of a menthol-containing sheet (when the polysaccharide is gellan gum).

DETAILED DESCRIPTION

The present invention will be described below. However, the purpose of the following description is to explain the present invention in detail and not to limit the present invention.

As the flavoring contained in the flavoring sheet of the present invention, any flavoring can be used without limitation as long as it is a flavoring used in smoking articles. Main flavorings include: menthol, tobacco leaf extract, natural plant flavorings (such as cinnamon, sage, vanilla, chamomile, kudzu, yarrow, cloves, lavender, cardamom, cloves (チョウジ), nutmeg, bergamot, geranium, honey essential oil, rose oil, lemon, orange, cassia bark, caraway, jasmine, ginger, coriander, vanilla extract, spearmint, mint, cinnamon, coffee, celery, quinoa, sandalwood, cocoa, ylang-ylang, fennel, aniseed, licorice, carob, plum extract, peach extract, etc.), sugars (such as glucose , fructose, isomerized sugar, caramel, etc.), cocoa (powder, extract, etc.), esters (such as isoamyl acetate, linalyl acetate, isoamyl propionate, linalyl butyrate, etc.), ketones (such as menthone, ionone, damascenone, ethyl maltol, etc.), alcohols (such as geraniol, linalool, anethole, eugenol, etc.), aldehydes (such as vanillin, benzaldehyde, anisaldehyde, etc.), lactones (such as γ-undecanolactone, γ-nonalactone, etc.), animal flavorings (such as musk, ambergris, civet, castoreum, etc.), hydrocarbons (such as limonene, pinene, etc.). Flavorings that are easily dispersed in a solvent by adding an emulsifier, such as hydrophobic flavorings and oil-soluble flavorings, can be preferably used. These flavorings can be used alone or in combination.

Hereinafter, the present invention will be described taking the case of using menthol as a flavor as an example.

1. Menthol-containing sheets for smoking articles

In one embodiment of the present invention, a menthol-containing sheet for smoking articles (hereinafter referred to as a menthol-containing sheet) can be manufactured by a method comprising the following steps: a process of spreading a raw material slurry in a sol state at a temperature of 60 to 90°C on a base material, wherein the raw material slurry comprises: a polysaccharide containing at least one of carrageenan and gellan gum, menthol, an emulsifier, and 70 to 95% by weight of water, and the content of menthol based on the polysaccharide is in the range of 100 to 1000% by weight; a process of cooling the spread raw material slurry to a sample temperature of 0 to 40°C to gelate it; and a heating and drying process, which includes heating the gelled raw material and drying it at a sample temperature of 70 to 100°C.

In this specification, "sample temperature" refers to the surface temperature of a sample (ie, slurry or sheet).

(1) Preparation of raw material slurry

In the present invention, the raw material slurry can be prepared by a method comprising the following steps: (i) mixing a polysaccharide containing at least one of carrageenan and gellan gum with water and heating the mixture to prepare an aqueous solution of the polysaccharide; and (ii) adding menthol and an emulsifier to the aqueous solution, followed by kneading and emulsification.

Specifically, step (i) can be performed as follows: the polysaccharide is added to water in small amounts and dissolved while stirring. The heating temperature can be 60-90°C, preferably 75-85°C. Step (ii) can be performed using a known emulsification technique using a homogenizer, as the raw material slurry has a viscosity of approximately 10,000 mPas (sol state) at the heating temperature, which does not hinder emulsification.

The polysaccharide is preferably contained in the raw material slurry at a concentration of 2 to 5% by weight. For example, when 10 L of water is used as the solvent for the raw material slurry, the raw material slurry may contain 200 to 500 g of polysaccharide. More preferably, the polysaccharide is contained in the raw material slurry at a concentration of 3 to 5% by weight (see Example 10 described below).

The raw material slurry may be formulated, for example, with respect to 10 L of water, 500 g of polysaccharide, 500 to 5000 g of menthol, and 50 to 500 ml of a 5 wt % emulsifier solution.

The water content of the raw material slurry is 70 to 95% by weight, preferably 80 to 90% by weight.

The ratio (weight ratio) of polysaccharide to menthol in the raw material slurry can be 1:1 to 1:10, preferably 1:2.5 to 1:5. Specifically, the amount of menthol added can be 100 to 1000% by weight relative to the weight of the polysaccharide, preferably 250 to 500% by weight relative to the weight of the polysaccharide (see Example 11 described below).

The polysaccharide in the raw material slurry only needs to contain either carrageenan or gellan gum, or it may contain both. Furthermore, the polysaccharide may consist solely of carrageenan and/or gellan gum, or may contain other polysaccharides in addition to carrageenan and/or gellan gum, such as tamarind gum. However, the content of other polysaccharides in the slurry should be less than the amount of carrageenan and gellan gum combined. κ-carrageenan may be used as the carrageenan.

In the present invention, polysaccharides have the property of gelling when temporarily cooled after heating, and fixing and coating the micelles of menthol. The present invention has found that the aqueous solutions of carrageenan and gellan gum show particularly excellent sol-gel transition characteristics relative to temperature (refer to Examples 4 and 9 described later). That is, if the carrageenan aqueous solution and the gellan gum aqueous solution are temporarily cooled and gelled, then even if the temperature rises, it is not easy to return to the sol, and has the characteristic of being able to maintain a gel state (refer to Figures 2B and 7B). Due to this characteristic, after the menthol coated with carrageenan or gellan gum is temporarily cooled, even if it is exposed to high temperature in the heating and drying process, its film will not return to the sol, and the menthol in the film can be stably maintained (refer to Figures 7D and 7F). In the present invention, this characteristic is referred to as "temperature-sensitive sol-gel transition characteristics".

Thus, polysaccharides having temperature-sensitive sol-gel transition properties have the advantage of encapsulating menthol and achieving high storage and flavor retention. They also have the advantage of utilizing temperature-sensitive sol-gel transition properties for gelation without the need for adding metal ions (gelation accelerators).

In the present invention, l-menthol can be used as menthol.

In the present invention, the emulsifier may be a naturally-derived emulsifier such as lecithin, and specifically, Sun Lecithin A-1 (from Taiyo Chemical Co., Ltd.) may be used.

When lecithin is used as an emulsifier, the lecithin can be contained in the slurry at 0.5 to 5% by weight relative to the polysaccharide. When carrageenan is used as the polysaccharide, the amount of lecithin added is preferably 0.5 to 2% by weight relative to the polysaccharide. Furthermore, when gellan gum is used as the polysaccharide, the amount of lecithin added is preferably 0.5 to 5% by weight, more preferably 0.5 to 2% by weight relative to the polysaccharide (see Example 12 described below).

As the emulsifier, in addition to lecithin, esters selected from glycerol fatty acid esters, polyglycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, and sucrose fatty acid esters can be used.

Examples of glycerol fatty acid esters include monoglyceryl monostearate and monoglyceryl succinate; examples of polyglyceryl fatty acid esters include pentaglyceryl monostearate; examples of sorbitan fatty acid esters include sorbitan monostearate; examples of propylene glycol fatty acid esters include propylene glycol monostearate; and examples of sucrose fatty acid esters include sucrose stearate (see Example 13 described below). These emulsifiers may also be included in the slurry in an amount of 0.5 to 5% by weight relative to the polysaccharide.

(2) Spreading of raw material slurry on the base material

The raw material slurry at 60-90° C. prepared as described above is spread on the base material.

The raw material slurry can be spread by extruding the raw material slurry onto a substrate through a slit die using a casting gate. The substrate can be any substrate from which the menthol-containing sheet produced by drying and forming can be peeled, such as polyethylene terephthalate (PET) film (Futamura Chemical Co., Ltd. FE2001). The raw material slurry can be spread, for example, so that its thickness when dried is approximately 0.1 mm, similar to that of conventional shredded tobacco.

(3) Cooling before slurry drying and forming

In the process for preparing the menthol-containing sheet of the present invention, the spread raw material slurry is temporarily cooled before drying to a temperature at which the slurry fully gels (below 40°C) and the emulsion generally does not freeze and break down (above 0°C), i.e., 0-40°C, preferably 0-30°C, and more preferably 15-25°C. The raw material slurry before cooling has a temperature of 60-90°C, preferably 75-85°C, and is in a sol state. This pre-cooling can be performed by blowing cold air (e.g., 10°C) generated by air supply or a local cooler (e.g., Sudden SS-25DD-1) through the spread raw material slurry for 2-3 minutes. Alternatively, pre-cooling can be performed by contacting the spread raw material slurry with a pipe through which a condensing medium (e.g., 10°C) generated by a hot and cold water generator (e.g., Apiste PCU-1600R) flows for 1-2 minutes. Alternatively, pre-cooling can be performed by leaving the spread raw material slurry at room temperature.

As shown in Examples 4 and 9 described below, the aqueous solutions of the polysaccharides exemplified above, once cooled and gelled, are less likely to solubilize even when the temperature subsequently rises, even at the temperature at which they become gels, and thus maintain their gelled state. The present invention utilizes this property to precool the raw material slurry before drying. Even if the temperature of the precooled raw material slurry rises during drying, the polysaccharides contained therein are less likely to solubilize. This, in turn, demonstrates that menthol coated with such polysaccharides is less likely to volatilize.

Another advantage is that when the raw material slurry is spread on the base material and temporarily cooled, the spread raw material slurry will not deform (collapse) even if it is exposed to high temperature in the subsequent drying process.

The effect of this cooling on the storage and flavor retention of a fragrance-containing sheet (e.g., a menthol-containing sheet) is demonstrated in Example 6 ( FIG. 4B ) described later. Lower cooling temperatures are associated with greater menthol content, as demonstrated in Example 7 ( FIG. 5 ) described later.

(4) Drying and forming of slurry

The raw material slurry that has been spread and cooled can be dried by heating using any heating drying method such as hot air drying, infrared heating drying, etc. Hereinafter, "heat drying" of the raw material slurry is also simply referred to as "drying."

In the present invention, drying the raw material slurry involves heating the cooled raw material slurry and drying it at a sample temperature of 70 to 100°C. Preferably, the sample temperature is kept below 100°C throughout the drying time. Drying at this sample temperature prevents volatilization of menthol and allows for the production of menthol-containing sheets in a short period of time.

Here, "sample temperature" refers to the surface temperature of the sample (i.e., slurry or sheet). Furthermore, "total drying time" refers to the time spent heating in the drying machine. The total drying time is generally 20 minutes or less, preferably 7 to 20 minutes, and more preferably 10 to 18 minutes.

In the present invention, the sample temperature may be below 70°C during the drying process. However, to shorten the drying time, the period during which the sample temperature is below 70°C is preferably short. Furthermore, in the present invention, the sample temperature may exceed 100°C during the drying process. However, to stably maintain flavorings such as menthol, the period during which the sample temperature exceeds 100°C is preferably short. Therefore, when drying the raw material slurry, it is preferred that the cooled raw material slurry be dried at a sample temperature of 70 to 100°C for at least half of the total drying time, and the sample temperature is preferably below 100°C during the total drying time. More preferably, the cooled raw material slurry is dried at a sample temperature of 70 to 100°C throughout the entire drying time, thereby achieving complete drying of the raw material slurry.

However, after the start of heating and drying, the sample temperature in the heating dryer rises from the pre-cooling temperature to the desired sample temperature (70°C). Since the desired sample temperature is not reached, the "total drying time" expressed as "the sample temperature is 70-100°C during the entire drying time" refers to the total drying time that does not include the initial period during which the sample temperature rises to the desired sample temperature. For example, in Example 5 (Figures 3A-3G) described below, the sample temperature rises to the desired sample temperature for approximately one minute from the start of heating. Therefore, the "total drying time" expressed as "the sample temperature is 70-100°C during the entire drying time" does not include this initial period.

The raw material slurry can be dried preferably by drying the raw material slurry in a total drying time of 20 minutes or less to a state having a moisture content of less than 10%.

When the raw material slurry is dried at the above-mentioned sample temperature, the sheet obtained by drying can achieve high storage and fragrance retention properties, which is confirmed in Example 5 (Figures 3D to 3G) described later.

The following describes hot air drying. In the case of hot air drying, in order to maintain a sample temperature of 70-100°C, it is preferred to initially dry the raw material slurry with hot air at a temperature of 100°C or higher. The slurry is then dried at a temperature equal to or lower than the initial hot air temperature (preferably 70°C or higher and lower than 100°C). This can suppress the sample temperature from rising in the later stages of drying, allowing, for example, the test temperature to be maintained at no more than 100°C throughout the entire drying time.

In the present invention, by temporarily cooling the prepared raw material slurry, even if a drying operation such as a sample temperature of 70 to 100°C (e.g., high-temperature drying using hot air at 100°C or higher) is included during the subsequent drying step, the menthol content of the produced menthol-containing sheet is increased, the menthol production yield is improved, and the menthol content can be maintained at a high value even after storage.

In the case of hot air drying, the hot air temperature may be a constant temperature throughout the drying process, or may vary during the drying process. In the case of changing the hot air temperature, it is preferred that the drying of the raw material slurry is performed by initial drying at a high temperature using hot air of 100°C or higher, followed by post-drying at a low temperature using hot air below 100°C. In this specification, "initial drying" refers to the initial drying of the drying process using hot air of a high temperature of 100°C or higher, and "post-drying" refers to drying following the initial drying using hot air of a low temperature of below 100°C. As described above, if initial drying using high-temperature hot air and post-drying using low-temperature hot air are combined, there is an advantage that the sample temperature does not become too high. In the case of hot air drying, the temperature inside the dryer is the same as the hot air temperature.

It is further preferred that the raw material slurry is dried by the following operation: initial drying is performed at a hot air temperature of 100°C or higher for more than 1/4 of the total drying time, and then post-drying is performed at a hot air temperature of less than 100°C for more than 1/4 of the total drying time, and the raw material slurry is dried in a total drying time of less than 20 minutes to a sheet having a moisture content of less than 10%.

By combining initial drying with high-temperature hot air and post-drying with low-temperature hot air as described above, the sample temperature can be suppressed from rising during post-drying, and, for example, the sample temperature can be maintained at no more than 100°C. As a result, the menthol-containing sheet of the present invention has a high menthol content immediately after production, and maintains a high menthol content even after storage (see Sample No. 4 in Example 1, Sample No. 5 in Example 2, and Sample No. 6 in Example 3, described below).

When drying the raw material slurry by hot air drying, initial drying can be performed at a hot air temperature of 100°C to 130°C for 4 to 6 minutes, and post-drying can be performed at a hot air temperature of 70°C to less than 100°C for 4 to 6 minutes. The hot air flow rate can be set to, for example, 3 to 20 m/s. The total drying time is generally 20 minutes or less, preferably 7 to 20 minutes, and more preferably 10 to 18 minutes.

The conditions for initial drying and post-drying (temperature, time, and air volume) can be appropriately set within the above-mentioned ranges. For example, the initial drying can be performed by evaporating the moisture on the surface of the raw material slurry at a hot air temperature of 100°C to 130°C until a sufficient film is formed on the surface of the slurry, and then the hot air temperature can be quickly switched to 70°C to less than 100°C for post-drying.

The hot air temperature during the initial drying period may be constant or may be changed in a gradually decreasing manner between 100°C and 130°C. In addition, the hot air temperature during the later drying period may be constant or may be changed in a gradually decreasing manner between 70°C and 100°C. For example, the hot air dryer used in the embodiments described later has three drying chambers, and the samples are conveyed by a conveyor belt in the order of the first chamber → the second chamber → the third chamber. Therefore, the first chamber and the second chamber may be used to perform initial drying at the same or different temperatures (above 100°C), and the third chamber may be used for later drying (below 100°C); or the first chamber may be used for initial drying (above 100°C), and the second chamber and the third chamber may be used to perform later drying at the same or different temperatures (below 100°C).

In the present invention, drying is performed until the menthol-containing sheet is sufficiently dry and can be easily peeled from the substrate and cut in the subsequent cutting process. Specifically, drying is performed until the moisture content of the menthol-containing sheet is less than 10% by weight, preferably 3 to 9% by weight, and more preferably 3 to 6% by weight (see Example 8 below). The moisture content refers to the value measured by the measurement method described in the examples below.

The menthol content of the menthol-containing sheet of the present invention (immediately after production) is preferably 45% by weight or greater, more preferably 55 to 75% by weight. Furthermore, the menthol content of the menthol-containing sheet of the present invention after storage (50°C, 30 days) is preferably 45% by weight or greater, more preferably 48 to 63% by weight. The menthol content herein refers to the value measured by the measurement method described in the Examples below.

2. Smoking articles

The menthol-containing sheet of the present invention can be cut into a size equivalent to conventional shredded tobacco and incorporated into the shredded tobacco of a smoking article. The menthol-containing sheet cuts can be incorporated in an amount of 2 to 10 g per 100 g of shredded tobacco. The menthol-containing sheet cuts are preferably dispersed throughout the shredded tobacco.

The menthol-containing sheet of the present invention can be incorporated into any smoking article, such as a combustion-type smoking article that burns tobacco leaves to enjoy the tobacco flavor, particularly shredded tobacco in cigarettes. In particular, the menthol-containing sheet of the present invention can be incorporated into shredded tobacco in cigarettes comprising a rod containing shredded tobacco and cigarette paper wrapped around the shredded tobacco.

Example

[Example 1]

(1) Preparation of raw material slurry (10L scale)

Water (10 L) was maintained at 80°C, and gellan gum (150 g) and tamarind gum (150 g) were dissolved in small portions while stirring in a mixer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a solution stirring rotor, 2000 rpm) to prevent agglomeration (approximately 20 minutes). Menthol (1500 g) was then added.

The stirring mixer was replaced with a homogenizer (PRIMIX T.K. AUTO MIXER Model 40/equipped with a rotor head/4000 rpm) and emulsification was performed for 10 minutes. Lecithin (120 mL (5% aqueous solution)) was then added and emulsification was continued for another 10 minutes to obtain a raw material slurry. Menthol was dispersed in the raw material slurry.

(2) Drying and forming

The resulting raw material slurry was extruded onto a substrate film through a slot die. The slurry was then cooled to approximately 20°C using cold air (10°C) from a local cooler (Suiden SS-25DD-1) for 2-3 minutes. The slurry was then conveyed on a conveyor belt in a hot air dryer for hot air drying, yielding a film-like menthol-containing sheet. The details of the experiment are described below.

Slit die: Vertical slit die (60°C heating and insulation), thickness 900μm, width 20cm

Base material film: PET film (surface corona treatment), thickness 50μm

Hot air dryer: A hot air drying and forming machine with the following structure

Drying area: 3 rooms (each area 2.5m long, total length 7.5m)

Hot air volume and form: Chamber 1: perforated plate, air volume 5m/s

: Chamber 2: Perforated plate, air volume 10m/s

: Chamber 3: Floating jet, air volume 20m/s

In the first and second chambers, hot air is blown toward the menthol-containing sheet being transported on the conveyor belt via perforated plates serving as flow control plates. In the third chamber, hot air is blown from above and below by ventilation toward the menthol-containing sheet being transported while floating along with the base film.

Menthol-containing sheets (Samples 1 to 4) were prepared by varying the hot air drying conditions as described in Table 1 below. The temperatures listed are hot air temperatures. The drying time was set to ensure that the menthol-containing sheets were sufficiently dry and easily peelable from the substrate film, and that the menthol-containing sheets could be cut in the subsequent cutting process. The moisture content of the menthol-containing sheets obtained in this example was approximately 3%.

(3) Measurement of Drying Condition of Menthol-Containing Sheets

The moisture content of the menthol-containing sheet was measured using GC-TCD as follows.

First, weigh 0.1g of a menthol-containing sheet (cut into 1x10mm pieces) and place it in a 50mL sealed container (threaded tube). Add 10mL of methanol (special grade reagent or equivalent; to eliminate the effects of moisture absorption from the air, dispense fresh product without exposure to the atmosphere) and shake for 40 minutes (200rpm). After standing overnight, shake again for 40 minutes (200rpm). The supernatant (not diluted for GC analysis) is used as the measurement solution.

The assay solution was quantified using the following GC-TCD calibration curve method.

GC-TCD: Hewlett Packard 6890 gas chromatograph

Column: HP Polapack Q (packed column) fixed flow rate mode 20.0 mL/min

Injection volume: 1.0 μL

Feed port: EPC flushing packed column feed port heater; 230℃

Gas: He Total flow rate: 21.1 mL/min

Oven: 160°C (hold for 4.5 minutes) → (60°C/min) → 220°C (hold for 4.0 minutes)

Detector: TCD detector Standard gas (He) flow rate: 20mL/min

Supplementary gas (He) 3.0 mL/min

Signal frequency 5Hz

Standard curve solution concentrations: 6 points: 0, 1, 3, 5, 10, 20 [mg-H2O/10mL].

(4) Determination of menthol content in menthol-containing sheets

The menthol content of the menthol-containing sheet was measured using GC-FID as follows.

First, 0.1 g of the menthol-containing sheet (cut into 1 x 10 mm pieces) was weighed and placed in a 50 mL sealed container (threaded tube). 10 mL of methanol (special grade reagent or equivalent; to eliminate the effects of moisture absorption from the air, new products were dispensed without exposure to the atmosphere) was added and shaken (200 rpm) for 40 minutes. After standing overnight, the mixture was shaken again (200 rpm) for 40 minutes. The supernatant (here diluted with 10 x methanol for GC analysis) was used as the measurement solution.

The measurement solution was quantified using the following GC-FID method using a calibration curve.

GC-FID: Agilent 6890N gas chromatograph was used

Column: DB-WAX 30m × 530μm × 1μm

Constant pressure mode 5.5 psi (speed; 50 cm/sec)

Injection volume: 1.0 μL

Feed inlet: splitless mode 250℃ 5.5psi

Oven: 80°C → (10°C/min) → 170°C (hold for 6.0 minutes) [maximum 220°C]

Detector: FID detector 250℃ (H2: 40mL/min, air: 450mL/min)

Signal frequency: 20Hz

Standard curve solution concentrations: 8 points: 0, 0.01, 0.05, 0.1, 0.3, 0.5, 0.7, and 1.0 [mg-menthol/mL].

The menthol content (mg) of the prepared menthol-containing sheet and the menthol content (mg) of the menthol-containing sheet after storage under an accelerated environment were measured and shown in Table 1 as "Initial menthol content (%)" and "Menthol content (%) after storage."

Initial menthol content (%) = {measured value of menthol content (mg) / weight of menthol-containing sheet (mg)} × 100

Menthol content after storage (%) = {measured value of menthol content (mg) / weight of menthol-containing sheet (mg)} × 100

The acceleration environment is described below.

A menthol-containing sheet (cut into 1×10 mm pieces, approximately 5 g) was placed in an open container and stored in a thermostat (Drying Oven DX600, manufactured by Yamato Scientific Co., Ltd.) set at 50° C. for up to 30 days.

The menthol flavor retention rate was calculated from the menthol content using the following formula, and the flavor retention function of the menthol-containing sheet was evaluated.

Menthol aroma retention rate (%) = {(menthol content after storage)/(initial menthol content)}×100

(5) Results

Menthol-containing sheets, sample numbers 1 to 4, were prepared using the hot air drying and forming machine described above under the hot air drying conditions described in Table 1. The moisture content and initial menthol content of the menthol-containing sheets were measured according to the above-described methods, and the results are shown in Table 1. The menthol content after 30 days of storage is shown in Table 1, and the menthol content after 7 days, 14 days, and 30 days of storage is shown in Figure 1. In Figure 1, reference numerals 1 to 7 represent sample numbers 1 to 7.

[Table 1]

Sample No. 1

When the raw material slurry is spread and dried to form a sheet using the aforementioned hot air drying and forming machine, the following method is often used: since a surface film is not formed in the first half of the drying process, drying is started at a low hot air temperature (around 70°C), and in the second half of the drying process, drying is continued at a high hot air temperature (around 120°C) to achieve complete drying. This method allowed the preparation of menthol-containing sheet material (Sample No. 1) to be fully dried within a total drying time of 12 minutes (moisture content 3.1%). Furthermore, the "initial menthol content" after sheet preparation was a very high 81.5%, but after storage (20 days) under an accelerated environment, the "post-storage menthol content" was as low as 13.6%. Therefore, Sample No. 1 had problems with its storage and flavor retention.

Sample No. 2

Sample No. 2 used a shorter drying time than Sample No. 1, thus employing a higher drying temperature. Consequently, Sample No. 2 was able to produce a fully dried sample (moisture content 3.2%) within a total drying time of 6 minutes. Furthermore, the initial menthol content of the sheet after preparation was a very high 62.4%, but after storage (30 days) under an accelerated environment, the post-storage menthol content was a low 29.2%. Therefore, Sample No. 2 had issues with its fragrance retention during storage.

Sample No. 3

Sample No. 3 set the hot air temperature to 70°C throughout the drying process. As a result, Sample No. 3 was able to produce a fully dried sample (moisture content 3.1%) within a total drying time of 60 minutes. In addition, the "initial menthol content" after sheet preparation was 75.8%, which was very high. In addition, the "menthol content after storage" after storage under an accelerated environment (30 days) was as high as 59.2%. Therefore, the aroma retention after sheet preparation and the aroma retention during storage were both good. However, the drying time was as long as 60 minutes.

Sample No. 4

Sample No. 4 is the opposite of Sample Nos. 1 and 2, which moved from low-temperature drying to high-temperature drying. Initial drying (chamber 1 and chamber 2) is performed with hot air at high temperature (120°C), and later drying (chamber 3) is performed with hot air at low temperature (70°C). Sample No. 4 can produce a fully dried sample (moisture content 3.4%) with a total drying time as short as 7.5 minutes. In addition, the "initial menthol content" after sheet preparation is 75.7%, which is very high. In addition, the "menthol content after storage" after storage (30 days) under an accelerated environment is as high as 62.4%. Therefore, the aroma retention of the sheet after preparation and the aroma retention during storage are both good. As mentioned above, if initial drying at high temperature and later drying at low temperature are adopted, a sheet with excellent aroma retention can be produced in a shorter drying time.

[Example 2]

A menthol-containing sheet of Sample No. 5 was prepared in the same manner as in Example 1, except that the slurry was dried under the hot air drying conditions described in Table 2 below. The moisture content and menthol content were measured. The results are shown in Table 2.

[Table 2]

Sample No. 5 had a higher hot air volume than Samples Nos. 1 to 4. In the first chamber, hot air was blown from above and below onto the floating and conveyed menthol-containing sheet. In the second and third chambers, hot air was blown onto the menthol-containing sheet conveyed on the conveyor belt.

Sample No. 5 was initially dried for 4 minutes with hot air at a high temperature (120°C) (chamber 1) and then later dried for 8 minutes with hot air at a low temperature (70°C) (chambers 2 and 3). Sample No. 5 was able to prepare a sample that was fully dried within a total drying time of 12 minutes (moisture content 3.1%). In addition, the "initial menthol content" after sheet preparation was 72.7%, which was very high. In addition, the "menthol content after storage" after storage under an accelerated environment (30 days) was as high as 58.5%. Therefore, the aroma retention of the sheet after preparation and the aroma retention during storage were both good. As described above, if initial drying at a high temperature and later drying at a low temperature are adopted, a sheet with excellent aroma retention can be prepared in a shorter drying time.

[Example 3]

Menthol-containing sheets of Sample Nos. 6 and 7 were prepared in the same manner as in Example 1, except that the slurry was dried using a hot air dryer with four drying compartments under the hot air drying conditions described in Table 3. The moisture content and menthol content were measured. The results are shown in Table 3.

[Table 3]

Sample Nos. 6 and 7 were prepared using a hot air drying and forming machine having four drying zones.

Sample No. 6 was initially dried for 6.6 minutes (chambers 1 to 3) using hot air at a high temperature (110°C → 100°C) and then post-dried for 2.2 minutes (chamber 4) using hot air at a low temperature (80°C). Sample No. 6 was able to produce a fully dried sample (moisture content 5%) within a total drying time of 8.8 minutes. In addition, the "initial menthol content" after sheet preparation was 63.5%, which was very high. In addition, the "menthol content after storage" after storage under an accelerated environment (30 days) was as high as 59.9%. Therefore, the aroma retention of the sheet after preparation and the aroma retention during storage were both good. Therefore, even if the hot air temperature during the initial drying period is changed in a manner that decreases in sequence from 110°C to 100°C, by adopting initial drying at a high temperature and post-drying at a low temperature, a sheet with excellent aroma retention can be produced in a shorter time.

Sample No. 7 did not differ in initial and final drying, both being dried with hot air at 100°C. Although Sample No. 7 did not employ low-temperature final drying, it is speculated that, similar to Samples Nos. 4-6, the sample temperature did not rise excessively during the slurry drying process due to the presence of moisture in the sample. Specifically, Sample No. 7 was able to produce a fully dried sample (moisture content 4.9%) within a total drying time of 8.8 minutes. Furthermore, the "initial menthol content" after sheet preparation was a remarkably high 61.9%, and the "menthol content after storage" after storage under an accelerated environment (30 days) was a high 60.8%, demonstrating excellent flavor retention both after sheet preparation and during storage. Thus, even with the same hot air temperature of 100°C throughout the drying process, sheets with excellent flavor retention can be produced within a relatively short drying time, similar to Samples Nos. 4-6.

[Example 4]

In this example, the temperature-sensitive sol-gel transition characteristics of a polysaccharide aqueous solution (slurry) were examined.

0.1L water

Gellan gum (Kelcogel/Sanrongyuan F·F·I) 5g

Water (0.1 L) was maintained at 70° C., and gellan gum (5 g) was dissolved in small portions without forming lumps using an Atec Japan high-performance mixer DMM while stirring to prepare a polysaccharide aqueous solution (slurry).

The slurry (70°C) was cooled to 25°C over about 900 seconds (0.05°C/second), and then heated to 70°C over about 900 seconds. Figures 2A and 2B show how the viscosity (fluidity) of the slurry changes with such temperature changes.

As shown in Figure 2A, if the slurry is cooled (cooled) to 25°C, the viscosity is low (high fluidity) up to 50°C, but the viscosity rises sharply below 40°C (gelation). If the gel is heated, as shown in Figure 2B, it is difficult to return to a sol even above the gelation temperature (40°C), and the gel state can be maintained up to very high temperatures.

These results indicate that if a slurry containing polysaccharides is temporarily cooled and gelled, it is unlikely to return to a sol even when the temperature rises, maintaining the gel state. By utilizing this property of polysaccharides in the present invention and precooling the raw material slurry before drying, it is expected that the polysaccharides contained in the precooled raw material slurry will not readily solubilize even when the temperature rises during drying, and the menthol coated with the polysaccharide will be less likely to volatilize.

[Example 5]

In this example, sheets of sample numbers 1 to 7 were prepared as described in Examples 1 to 3, and the temperature of the samples was measured during the drying process. The hot air drying conditions of the samples of sample numbers 1 to 7 can be referred to Tables 1 to 3.

The sample temperature can be measured by directly measuring the sample (slurry) during the drying step using a non-contact thermometer (PT-7LD, manufactured by Optics Corporation).

The measurement results for Samples 1 to 7 are shown in Figures 3A to 3G, respectively. In Figures 3A to 3G, "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying process, while "uncooled" refers to samples that were quickly dried after slurry casting without such cooling. The results in Figures 3A to 3G demonstrate that cooling the slurry does not affect the sample temperature during the drying process.

Sample No. 1 was dried using the following hot air drying conditions: 70°C for 4 minutes, 80°C for 4 minutes, and 120°C for 4 minutes. The sample temperature increased with the increase in hot air temperature, eventually exceeding 100°C and reaching nearly 120°C (Figure 3A). The "menthol content after storage" of the sheet of Sample No. 1 was a low 13.6% (Table 1). It is believed that the internal structure of the sheet was destroyed by the high sample temperature, resulting in a decrease in menthol content after storage.

Sample No. 2 was dried using the following hot air drying conditions: drying at 120°C for 2 minutes, then at 130°C for 2 minutes, and then at 176°C for 2 minutes. The sample temperature increased with the increase in hot air temperature, ultimately exceeding 100°C and reaching nearly 140°C (Figure 3B). The "menthol content after storage" of the sheet of Sample No. 2 was a low 29.2% (Table 1). It is believed that the internal structure of the sheet was destroyed by the high sample temperature, resulting in a decrease in menthol content after storage.

Sample No. 3 adopted the following conditions as hot air drying conditions: drying at a hot air temperature of 70°C for 60 minutes. Figure 3C shows the sample temperature from the start of drying to 14 minutes later, but the sample temperature did not exceed 70°C during the entire total drying time. The "menthol content after storage" of the sheet of sample No. 3 showed a high value of 59.2% (Table 1). It is believed that since the sheet of sample No. 3 does not reach a high temperature during the entire total drying time, a high menthol content can be maintained after storage under an accelerated environment. However, since the sheet of sample No. 3 was dried at a sample temperature lower than 70°C, a drying time of 60 minutes was required.

Sample No. 4 was dried under the following hot air drying conditions: drying at a hot air temperature of 120°C for 5 minutes, followed by drying at a hot air temperature of 70°C for 2.5 minutes. The sample temperature reached a maximum of 95°C at a hot air temperature of 120°C and dropped to 72°C at a hot air temperature of 70°C ( FIG. 3D ). The "menthol content after storage" of the sheet of Sample No. 4 was a high value of 62.4% (Table 1). It is believed that the sheet of Sample No. 4 maintained a lower sample temperature than Samples Nos. 1 and 2 throughout the total drying time, thus maintaining a higher menthol content after storage under an accelerated environment.

Sample No. 5 was dried under the following hot air drying conditions: drying at a hot air temperature of 120°C for 4 minutes, followed by drying at a hot air temperature of 70°C for 8 minutes. The sample temperature reached a maximum of 95°C at a hot air temperature of 120°C and dropped to 70°C at a hot air temperature of 70°C (Figure 3E). The "menthol content after storage" of the sheet of Sample No. 5 was a high value of 58.5% (Table 2). It is believed that the sheet of Sample No. 5 maintained a lower sample temperature than Samples Nos. 1 and 2 throughout the total drying time, and therefore, was able to maintain a higher menthol content after storage under an accelerated environment.

Sample No. 6 used the following hot air drying conditions: drying at a hot air temperature of 110°C for 2.2 minutes, then drying at a hot air temperature of 100°C for 4.4 minutes, and then drying at a hot air temperature of 80°C for 2.2 minutes. The sample temperature was maintained in the range of approximately 80-90°C ( FIG. 3F ). The "menthol content after storage" of the sheet of Sample No. 6 was a high value of 59.9% (Table 3). It is believed that the sheet of Sample No. 6 maintained a lower sample temperature than Samples Nos. 1 and 2 throughout the total drying time, thereby maintaining a higher menthol content after storage in an accelerated environment.

Sample No. 7 used the following hot air drying conditions: drying at a hot air temperature of 100°C for 8.8 minutes. The sample temperature was maintained in the range of approximately 80-90°C (Figure 3G). The "menthol content after storage" of the sheet of Sample No. 7 was a high value of 60.8% (Table 3). It is believed that the sheet of Sample No. 7 maintained a lower sample temperature than Samples Nos. 1 and 2 throughout the total drying time, thus maintaining a higher menthol content after storage in an accelerated environment.

The above results show that if the slurry is dried at a sample temperature of no more than 100°C during the total drying time, a high "menthol content after storage" can be maintained. Furthermore, it is shown that if the slurry is dried at a sample temperature of 70-100°C during the total drying time (excluding the initial drying time of approximately 1 minute), a sheet containing menthol can be formed in a short period of time.

[Example 6]

In this example, the effect of cooling the slurry before the drying step on the "menthol content after storage" of menthol-containing sheets was demonstrated. Specifically, sheets numbered 1 to 7 were prepared as described in Examples 1 to 3. The "menthol content after storage" of the sheets prepared by cooling the slurry was compared with the "menthol content after storage" of the sheets prepared without cooling the slurry. Storage was performed as described in Example 1, with the sheets placed in a thermostat set at 50°C for 7, 14, and 30 days.

The measurement results for Samples 1 to 3 are shown in Figure 4A , and the measurement results for Samples 4 to 7 are shown in Figure 4B . In Figures 4A and 4B , "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying step, while "uncooled" refers to samples that were dried quickly after slurry casting without such cooling. For the "uncooled" samples, the slurry temperature did not fall below 50°C during the period from casting to drying.

The “after cooling” data in FIG. 4A and FIG. 4B are the same as the data in FIG. 1 .

Regardless of whether the sheets of Sample Nos. 1 and 2 were cooled or not, the menthol content after storage for 30 days was low, less than 30%.

The menthol content of the sheet of Sample No. 3 after storage for 30 days was high, exceeding 50%, regardless of whether it was cooled or not. However, the preparation of the sheet of Sample No. 3 required a drying time of 60 minutes.

In the sheet of sample No. 4, the menthol content decreased to 18% after 30 days of storage in the "uncooled" condition. In contrast, the menthol content remained at 62% after 30 days of storage in the "cooled" condition.

In the sheet of sample No. 5, the menthol content decreased to 20% after 30 days of storage in the "uncooled" condition. In contrast, the menthol content remained at 59% after 30 days of storage in the "cooled" condition.

In the sheet of sample No. 6, the menthol content decreased to 20% after 30 days of storage in the "uncooled" condition. In contrast, the menthol content remained at 60% after 30 days of storage in the "cooled" condition.

In the sheet of sample No. 7, the menthol content decreased to 12% after 30 days of storage in the "uncooled" condition. In contrast, the menthol content remained at 61% after 30 days of storage in the "cooled" condition.

The above results show that if a menthol-containing sheet is prepared by temporarily cooling the raw material slurry and then drying it at a sample temperature of 70 to 100°C, the sheet can be formed in a short time and a high menthol content can be maintained even after storage.

[Example 7]

In this example, the relationship between the cooling temperature of the slurry and the "initial menthol content" of menthol-containing sheets was examined. Specifically, various sheets were prepared using Sample No. 6 described in Example 3, with the slurry cooling temperature varied to 20°C, 30°C, 40°C, 50°C, and 60°C. The menthol content of the sheets immediately after production, or the "initial menthol content," was measured.

The measurement results are shown in Figure 5. The results in Figure 5 confirm a tendency for the menthol content of the sheet to increase as the cooling temperature decreases. Specifically, at a cooling temperature of 20°C, the initial menthol content was 64%, at a cooling temperature of 30°C, the initial menthol content was 61%, at a cooling temperature of 40°C, the initial menthol content was 57%, at a cooling temperature of 50°C, the initial menthol content was 52%, and at a cooling temperature of 60°C, the initial menthol content was 43%.

In Example 4 above, it was shown that slurries gel at temperatures below 40°C, and that slurries containing polysaccharides, if temporarily cooled and gelled, are unlikely to return to a sol even after the temperature is raised. Furthermore, it is generally known that emulsions freeze and break down if the temperature is below 0°C.

From these results, it is understood that a cooling temperature of 0 to 40°C is preferred, and a cooling temperature of 0 to 30°C is more preferred.

[Example 8]

In this example, the relationship between the moisture content of menthol-containing sheets and their aroma retention was examined. Specifically, for sheet No. 6 described in Example 3, the conveyor speed within the hot air dryer was increased to reduce the total drying time of the slurry to 8.16 minutes, 7.92 minutes, 7.64 minutes, 7.44 minutes, and 7.08 minutes. Sheets with various moisture contents were then prepared. The moisture content of the prepared sheets was measured. The sheet preparation conditions and moisture content are shown in Table 4 below.

[Table 4]

Sample number 8-1 8-2 8-3 8-4 8-5 Conveyor belt speed 1.13m/min 1.07m/min 1.04m/min 1.01m/min 0.98m/min Total drying time 7.08 minutes 7.44 minutes 7.64 minutes 7.92 minutes 8.16 minutes Moisture content after drying 22.6wt% 14.6wt% 11.2wt% 8.6wt% 6.1wt%

As described in Example 1, the prepared sheets were placed in a thermostat set at 50°C for 30 days. The menthol content of the sheets was measured immediately after production and after storage. The results are shown in Table 5 below as "Initial Menthol Content" and "Menthol Content of Sheets Immediately After Production and After Storage." The menthol flavor retention rate was calculated from these menthol content values using the following formula.

Menthol aroma retention rate (%) = {(menthol content after storage)/(initial menthol content)}×100

The results are shown in FIG6 as “immediately after manufacture, acceleration device”.

Separately, two months after production, the sheets were placed in a thermostat set at 50°C for 30 days as described in Example 1. Menthol content was measured for the sheets immediately after production and after storage. The results are shown in Table 5 below as "Initial Menthol Content" and "Menthol Content of Sheets Stored Two Months After Production." Furthermore, the menthol flavor retention rate was calculated using the above formula. The results are shown in Figure 6 as "Two Months After Production, Accelerator" format.

[Table 5]

The menthol content of the sheets immediately after production was approximately 50 to 60% in all of Sample Nos. 8-1 to 8-5.

In an experiment in which the newly prepared sheets were stored under an accelerated environment, the sheet with a moisture content of about 6% (sample number 8-5) showed a menthol aroma retention rate of 93%, the sheet with a moisture content of about 9% (sample number 8-4) showed a menthol aroma retention rate of 90%, the sheet with a moisture content of about 11% (sample number 8-3) showed a menthol aroma retention rate of 87%, the sheet with a moisture content of about 15% (sample number 8-2) showed a menthol aroma retention rate of 63%, and the sheet with a moisture content of about 23% (sample number 8-1) showed a menthol aroma retention rate of 6%.

In an experiment in which sheets prepared two months later were stored under an accelerated environment, a sheet having a moisture content of approximately 6% (sample number 8-5) showed a menthol aroma retention rate of 95%, a sheet having a moisture content of approximately 9% (sample number 8-4) showed a menthol aroma retention rate of 87%, a sheet having a moisture content of approximately 11% (sample number 8-3) showed a menthol aroma retention rate of 32%, a sheet having a moisture content of approximately 15% (sample number 8-2) showed a menthol aroma retention rate of 8%, and a sheet having a moisture content of approximately 23% (sample number 8-1) showed a menthol aroma retention rate of 8%.

These results indicate that increasing the moisture content of the sheet material significantly reduces the menthol flavor retention rate. Therefore, it is preferable to dry the sheet material to a moisture content of less than 10%, preferably less than 9%. In particular, even when the sheet material is further stored under an accelerated temperature for two months after production, a high menthol flavor retention rate is maintained if the moisture content of the sheet material is approximately 9% or less.

When the moisture content of the sheet is less than 3%, the menthol flavor retention rate is good, but the sheet may crack or fall off. Therefore, the moisture content of the sheet after drying is preferably 3% or more.

[Example 9]

In this example, the effect of the type of polysaccharide on the menthol content of menthol-containing sheets after storage was examined. Carrageenan, gellan gum, pectin, and konjac glucomannan were used as the polysaccharides.

9-1. Method (Temperature-Sensitive Sol-Gel Transition Characteristics)

In this experiment, the temperature-sensitive sol-gel transition characteristics of polysaccharide aqueous solutions were investigated.

(1) Carrageenan aqueous solution

0.1L water

κ-Carrageenan (Carrageenin CS-530/Sanrongyuan F·F·I) 5g

(2) Gellan gum aqueous solution

As described in Example 4.

(3) Pectin aqueous solution

0.1L water

Pectin (Wako Pure Chemical Industries, Ltd., citrus-derived for chemical use) 3g

(4) Konjac Glucomannan Aqueous Solution

0.1L water

Konjac Glucomannan (Gunma Prefecture Konjac Raw Material Suppliers Industrial Cooperative Association) 1g

The polysaccharide aqueous solution of the above composition was prepared according to the method of Example 4.

The polysaccharide aqueous solution was cooled to 25°C over approximately 900 seconds. The temperature was then raised over approximately 900 seconds. A rheometer (RheoStress 1, manufactured by Thermo-Haake) was used to measure how the viscosity (fluidity) of the polysaccharide aqueous solution changes with cooling and heating. The results for the carrageenan aqueous solution are shown in Figures 7A and 7B , the results for the gellan gum aqueous solution are shown in Figures 2A and 2B , the results for the pectin aqueous solution are shown in Figures 7G and 7H , and the results for the konjac glucomannan aqueous solution are shown in Figures 7K and 7L .

9-2. Results (Temperature-Sensitive Sol-Gel Transition Characteristics)

As shown in Figure 7A, when the carrageenan aqueous solution is cooled to 25°C, its viscosity decreases to approximately 50°C, the sol-gel transition temperature (approximately 1,000 mPas or less). At temperatures below the transition temperature, the viscosity rises sharply, reaching 10,000,000 mPas (gelation). When the gel is heated, as shown in Figure 7B, even when heated above the transition temperature, it does not readily return to a sol state and remains in a gel state.

As shown in FIG. 2A and FIG. 2B , when the gellan gum aqueous solution is temporarily cooled and gelled, it is difficult to return to a sol even if it is subsequently heated above the transition temperature and can maintain the gel state (see Example 4).

Carrageenan aqueous solution and gellan gum aqueous solution have "temperature-sensitive sol-gel transition characteristics".

On the other hand, as shown in Figures 7G and 7H, the pectin aqueous solution does not have "temperature-sensitive sol-gel transition characteristics".

In addition, as shown in Figures 7K and 7L, konjac glucomannan also does not have "temperature-sensitive sol-gel transition characteristics".

9-3. Method (Preparation of Sheet)

In this experiment, menthol-containing sheets were prepared using each polysaccharide aqueous solution, and the temperature of the sample was measured during the heat drying step.

The sheet was prepared in the same manner as in Example 1 as follows.

(1) Preparation of carrageenan-containing sheets

In 10 L (100 parts by weight) of water (heated and insulated at 80°C) using a stirrer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a solution stirring rotor at 2000 rpm), 500 g (5 parts by weight) of κ-carrageenan was dissolved in small portions to prevent clumping (approximately 20 minutes). At this temperature, 2500 g (25 parts by weight) of l-menthol was added. The stirring dispersing machine was replaced with a homogenizer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a rotor head at 4000 rpm) and emulsified for 10 minutes. Then, 200 mL (2 parts by weight) of a 5% lecithin aqueous solution was added and stirred. The menthol was dispersed in the carrageenan aqueous solution.

The dispersed slurry was cast onto a substrate (PET film, Futamura Chemical Co., Ltd. FE2001) with a thickness of 1 mm (in a wet state) and then cooled to approximately 20°C using a local cooler (Suiden SS-25DD-1) with a cold air flow of approximately 10°C.

The sheet was then dried and formed in a hot air dryer using the same method as in Example 1 until the moisture content reached approximately 6%, thereby producing a carrageenan-containing sheet. The moisture content was measured by GC-TCD (see Example 1). Hot air drying conditions were as follows: drying at 110°C for 3 minutes, then at 100°C for 6 minutes, and finally at 80°C for 3 minutes (total drying time: 12 minutes).

The photo film (uncooled) was prepared by drying the cast slurry without cooling it. The hot air drying conditions for the photo film were as follows: drying at a hot air temperature of 110°C for 2.5 minutes, then drying at a hot air temperature of 100°C for 5 minutes, and then drying at a hot air temperature of 80°C for 2.5 minutes (total drying time 10 minutes).

The sample temperature was measured using a non-contact thermometer in the same manner as in Example 5. Figure 7C shows the change in sample temperature during the drying process. Here, "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying process, while "uncooled" refers to samples that were dried quickly after slurry casting without such cooling. Figure 7C shows that cooling the slurry did not affect the sample temperature during the drying process.

(2) Preparation of Sheets Containing Gellan Gum

In 10 L (100 parts by weight) of water (heated and insulated at 80°C) using a stirrer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a solution stirring rotor at 2000 rpm), 300 g (3 parts by weight) of gellan gum was dissolved in small portions to prevent clumping (approximately 20 minutes). At this temperature, 1500 g (15 parts by weight) of l-menthol was added. The stirring dispersant was replaced with a homogenizer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a rotor head at 4000 rpm) and emulsified for 10 minutes. Then, 120 mL (1.2 parts by weight) of a 5% lecithin aqueous solution was added and stirred. The menthol was dispersed in the gellan gum aqueous solution.

The dispersed slurry was cast onto a substrate (PET film, Futamura Chemical Co., Ltd. FE2001) with a thickness of 1 mm (in a wet state) and then cooled to approximately 20°C using a local cooler (Suiden SS-25DD-1) with a cold air flow of approximately 10°C.

The sheet was then dried and formed in a hot air dryer in the same manner as in Example 1 until its moisture content reached approximately 6%, thereby producing a gellan gum-containing sheet. The moisture content was measured by GC-TCD (see Example 1). Hot air drying conditions were as follows: drying at a hot air temperature of 110°C for 2.8 minutes, then at a hot air temperature of 100°C for 5.5 minutes, and finally at a hot air temperature of 80°C for 2.8 minutes (total drying time approximately 11 minutes).

The photo film (uncooled) was prepared by drying the cast slurry without cooling it. The hot air drying conditions for the photo film were as follows: drying at a hot air temperature of 110°C for 2.3 minutes, then drying at a hot air temperature of 100°C for 4.5 minutes, and then drying at a hot air temperature of 80°C for 2.3 minutes (total drying time 9 minutes).

The sample temperature was measured using a non-contact thermometer in the same manner as in Example 5. Figure 7E shows the changes in sample temperature during the drying process. Here, "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying process, while "uncooled" refers to samples that were dried quickly after slurry casting without such cooling. Figure 7E shows that cooling of the slurry did not affect the sample temperature during the drying process.

(3) Preparation of pectin-containing sheets

In 10 L (100 parts by weight) of water (heated and insulated at 80°C) using a stirrer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a solution stirring rotor at 2000 rpm), dissolve 300 g (3 parts by weight) of pectin in small portions to prevent clumping (approximately 20 minutes). At this temperature, add 1500 g (15 parts by weight) of l-menthol. Emulsify the mixture for 10 minutes using a homogenizer (PRIMIX T.K. AUTO MIXER Model 40, equipped with a rotor head at 4000 rpm). Add 120 mL (1.2 parts by weight) of a 5% lecithin aqueous solution and stir. Disperse the menthol in the pectin aqueous solution.

The dispersed slurry was cast onto a substrate (PET film, Futamura Chemical Co., Ltd. FE2001) with a thickness of 1 mm (in a wet state) and then cooled to approximately 20°C using a local cooler (Suiden SS-25DD-1) with a cold air flow of approximately 10°C.

The sheet was then dried and formed in a hot air dryer in the same manner as in Example 1 until its moisture content reached approximately 6%, thereby producing a pectin-containing sheet. The moisture content was measured by GC-TCD (see Example 1). Hot air drying conditions were as follows: drying at a hot air temperature of 110°C for 2.8 minutes, then at a hot air temperature of 100°C for 5.5 minutes, and finally at a hot air temperature of 80°C for 2.8 minutes (total drying time approximately 11 minutes).

The photo film (uncooled) was prepared by drying the cast slurry without cooling it. The hot air drying conditions for the photo film were as follows: drying at a hot air temperature of 110°C for 2.5 minutes, then drying at a hot air temperature of 100°C for 5 minutes, and then drying at a hot air temperature of 80°C for 2.5 minutes (total drying time 10 minutes).

The sample temperature was measured using a non-contact thermometer in the same manner as in Example 5. Figure 7I shows the changes in sample temperature during the drying process. Here, "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying process, while "uncooled" refers to samples that were dried immediately after slurry casting without such cooling. Figure 7I shows that cooling the slurry did not affect the sample temperature during the drying process.

(4) Preparation of sheet containing konjac glucomannan

In 10 L (100 parts by weight) of water (heated and insulated at 80°C), dissolve 100 g (1 part by weight) of konjac glucomannan in small portions, stirring to prevent clumping (approximately 20 minutes). Add 500 g (5 parts by weight) of l-menthol at the same temperature. Emulsify the mixture for 10 minutes by switching from the stirring dispersing machine to a homogenizer (PRIMIX T.K. AUTO MIXER Model 40 equipped with a rotor head). Then, add 40 mL (0.4 parts by weight) of a 5% lecithin aqueous solution and stir. The menthol is dispersed in the konjac glucomannan aqueous solution.

The dispersed slurry was cast onto a substrate (PET film, Futamura Chemical Co., Ltd. FE2001) with a thickness of 1 mm (in a wet state) and then cooled to approximately 20°C using a local cooler (Suiden SS-25DD-1) with a cold air flow of approximately 10°C.

The sheet was then dried and formed in a hot air dryer in the same manner as in Example 1 until its moisture content reached approximately 6%, thereby producing a sheet containing konjac glucomannan. The moisture content was measured by GC-TCD analysis (see Example 1). The hot air drying conditions were as follows: drying at a hot air temperature of 110°C for 3 minutes, then drying at a hot air temperature of 100°C for 6 minutes, and finally drying at a hot air temperature of 80°C for 3 minutes (total drying time: 12 minutes).

The photo film (uncooled) was prepared by drying the cast slurry without cooling it. The hot air drying conditions for the photo film were as follows: drying at a hot air temperature of 110°C for 2.5 minutes, then drying at a hot air temperature of 100°C for 5 minutes, and then drying at a hot air temperature of 80°C for 2.5 minutes (total drying time 10 minutes).

The sample temperature was measured using a non-contact thermometer in the same manner as in Example 5. Figure 7M shows the change in sample temperature during the drying process. Here, "cooled" refers to samples that were cooled to approximately 20°C by blowing cold air (10°C) before the drying process, while "uncooled" refers to samples that were dried quickly after slurry casting without such cooling. Figure 7M shows that cooling the slurry did not affect the sample temperature during the drying process.

9-4. Method (Determination of Menthol Content)

The menthol content of the sheets immediately after production (initial menthol content) and after storage under an accelerated environment (menthol content after storage) were measured. The accelerated environment was the same as described in Example 1, and the menthol content was measured using the same method as in Example 1. The results for the sheet containing carrageenan are shown in Figure 7D , the results for the sheet containing gellan gum are shown in Figure 7F , the results for the sheet containing pectin are shown in Figure 7J , and the results for the sheet containing konjac glucomannan are shown in Figure 7N .

9-5. Results (Menthol Content)

As shown in Figure 7D , when the carrageenan-containing sheet was cooled before the drying step, the initial menthol content was approximately 80% by weight, and after 30 days of storage, the menthol content was 60% by weight or higher (menthol flavor retention rate = approximately 80%). On the other hand, when the sheet was not cooled before the drying step, the initial menthol content was approximately 80% by weight, but after 30 days of storage, the menthol content was approximately 45% by weight (menthol flavor retention rate = approximately 60%).

As shown in Figure 7F , for a sheet containing gellan gum, when the slurry was cooled before the drying step, the initial menthol content was approximately 70% by weight, and after 30 days of storage, the menthol content was 65% by weight (menthol flavor retention rate = approximately 90% or more). On the other hand, when the sheet was not cooled before the drying step, the initial menthol content was approximately 55% by weight, and after 30 days of storage, the menthol content was approximately 35% by weight (menthol flavor retention rate = approximately 65%).

As shown in FIG7J , the pectin-containing sheet exhibited an initial menthol content of approximately 60% by weight, regardless of whether the slurry was cooled before the drying step. The menthol content after 30 days of storage was approximately 30% by weight (menthol flavor retention rate = approximately 55% to approximately 65%).

As shown in FIG7N , the sheet containing konjac glucomannan showed an initial menthol content of about 30% by weight, regardless of whether the slurry was cooled before the drying step. The menthol content after 30 days of storage was about 15% by weight (menthol flavor retention rate = about 50%).

The above results show that when carrageenan or gellan gum is used as the polysaccharide and the sheet is temporarily cooled before drying, the menthol content of the obtained sheet is high and the menthol production yield is high. In addition, the menthol content is maintained even after storage.

Therefore, in the following examples, carrageenan or gellan gum was used as the polysaccharide, and the polysaccharide was temporarily cooled before drying.

[Example 10]

In this example, the effect of the concentration of polysaccharides on the menthol content of menthol-containing sheets after storage was examined.

10-1. Method (Temperature-Sensitive Sol-Gel Transition Characteristics)

In this experiment, the temperature-sensitive sol-gel transition properties of raw material slurries (sheet preparation solutions) containing various concentrations of polysaccharides were examined. Carrageenan was used at 1 part (1%), 2 parts (2%), 3 parts (3%), 5 parts (5%), and 7 parts (7%) by weight relative to 100 parts by weight of water, and gellan gum was used at 1 part (1%), 2 parts (2%), 3 parts (3%), 5 parts (5%), and 7 parts (7%) by weight relative to 100 parts by weight of water. In the following description and Figures 8A to 8F, the polysaccharide concentration is expressed as a weight percentage (%) relative to water.

A carrageenan-containing raw material slurry and a gellan gum-containing raw material slurry were prepared according to the description in column 9-3 of Example 9. Depending on the concentration of the polysaccharide, menthol was added in an amount (weight ratio) 5 times that of the polysaccharide, and a 5% lecithin aqueous solution was added in an amount (weight ratio) 2/5 times that of the polysaccharide.

Raw material slurries containing various polysaccharide concentrations were cooled from 70°C to 25°C over approximately 900 seconds. The temperature was then raised to 70°C over approximately 900 seconds. A rheometer (RheoStress 1, manufactured by Thermo-Haake) was used to measure changes in the viscosity (fluidity) of the slurries as the temperature was lowered and raised. The results for the slurry containing carrageenan are shown in Figures 8A and 8B , and those for the slurry containing gellan gum are shown in Figures 8D and 8E .

10-2. Results (Temperature-Sensitive Sol-Gel Transition Characteristics)

As shown in Figures 8A and 8B , a raw material slurry containing 1% by weight of carrageenan did not fully gel even after cooling to 25°C, and it was difficult to maintain a gel state when the raw material was heated. Furthermore, a raw material slurry containing 7% by weight of carrageenan experienced an increase in viscosity during the initial cooling process (in the range of 70-60°C), making it difficult to maintain a sol state. Consequently, it was difficult to disperse menthol during the preparation of the raw material slurry.

Therefore, carrageenan is preferably contained in the raw material slurry at a concentration of 2 to 5% by weight.

As shown in Figures 8D and 8E , a raw material slurry containing 1% by weight of gellan gum did not fully gel even after cooling to 25°C, and it was difficult to maintain a sol state when the raw material was heated. Furthermore, a raw material slurry containing 7% by weight of gellan gum experienced an increase in viscosity during the initial cooling process (in the range of 70-60°C), making it difficult to maintain a sol state. Consequently, it was difficult to disperse menthol during the preparation of the raw material slurry.

Therefore, gellan gum is preferably contained in the raw material slurry at a concentration of 2 to 5% by weight.

10-3. Method (Preparation of Sheet and Determination of Menthol Content)

Carrageenan-containing sheets and gellan gum-containing sheets were prepared using the raw material slurries containing polysaccharides at various concentrations (see column 10-1). The sheets were prepared in the same manner as in Example 9.

The menthol content of the sheets immediately after production (initial menthol content) and the menthol content of the sheets stored under an accelerated environment (menthol content after storage) were measured. The accelerated environment was as described in Example 1. The menthol content was measured using the same method as in Example 1. The results for the sheets containing carrageenan are shown in Figure 8C , and the results for the sheets containing gellan gum are shown in Figure 8F .

10-4. Results (Menthol Content)

As shown in Figure 8C , the carrageenan-containing sheet showed an initial menthol content of approximately 80% by weight for both the 3% and 5% carrageenan concentrations, and a menthol content of approximately 60% by weight after 30 days of storage (menthol flavor retention rate = approximately 80%). With 2% carrageenan, the initial menthol content was 74% by weight, and after 30 days of storage, the menthol content exceeded 50% by weight (menthol flavor retention rate = 68%). Furthermore, with 6% carrageenan, the initial menthol content was 69% by weight, and after 30 days of storage, the menthol content was 43% by weight (menthol flavor retention rate = 62%).

As shown in Figure 8F , the gellan gum-containing sheet showed an initial menthol content of approximately 70% by weight for both the 3% and 5% by weight cases, and the menthol content after 30 days of storage was close to 70% by weight (menthol flavor retention rate = approximately 90%). In the 2% by weight case, the initial menthol content was 70% by weight, and the menthol content after 30 days of storage exceeded 50% by weight (menthol flavor retention rate = 78%). Furthermore, in the 6% by weight case, the initial menthol content was 76% by weight, and the menthol content after 30 days of storage was 63% by weight (menthol flavor retention rate = 83%).

From these results, it is understood that carrageenan and gellan gum are preferably contained in the raw material slurry at a concentration of 2 to 6% by weight, and more preferably contained in the raw material slurry at a concentration of 3 to 5% by weight.

[Example 11]

In this example, the effect of the menthol blending ratio in the raw material slurry on the menthol content and menthol yield of the menthol-containing sheet after storage was examined.

11-1. Method (Preparation of Sheet and Determination of Menthol Content)

Carrageenan-containing sheets and gellan gum-containing sheets were prepared using raw material slurries having various menthol blending ratios. The sheets were prepared in the same manner as in Example 9.

For sheets containing carrageenan, menthol was blended in amounts of 1, 2.5, 5, 10, 15, or 20 times the weight of carrageenan relative to 5% by weight (in the raw material slurry). For sheets containing gellan gum, menthol was blended in amounts of 0.5, 1, 2.5, 5, 10, 15, or 20 times the weight of gellan gum relative to 3% by weight (in the raw material slurry).

The menthol content of the sheet immediately after production (initial menthol content) and the menthol content of the sheet stored under an accelerated environment (menthol content after storage) were measured. The accelerated environment is as described in Example 1. The menthol content was measured using the same method as in Example 1. The results for the sheet containing carrageenan are shown in Figures 9A to 9E, and the results for the sheet containing gellan gum are shown in Figures 9F to 9J. In these figures, the mark [1:x] represents the weight ratio of the polysaccharide and menthol in the raw material slurry. For example, [1:5] means that the raw material slurry contains 5 times the weight of menthol relative to the polysaccharide. In addition, in these figures, "immediately after production" means immediately after the sheet is produced, and "50°C·1 month later" means after storage at 50°C for 30 days.

11-2. Results

(1) Sheets containing carrageenan

As shown in Figure 9A , the "initial menthol content" of carrageenan-containing sheets was highest in the case of the sheet containing 10 times the weight of menthol, followed by 5 times the weight, then 2.5 times the weight, and finally 1 time the weight. These results depended on the menthol content. On the other hand, the "initial menthol content" of the sheets containing 15 times and 20 times the weight of menthol was particularly low, below 20% by weight. The "menthol content after storage" showed little decrease relative to the initial menthol content at any menthol content. Therefore, as shown in Figure 9B , the menthol flavor retention rate after 30 days of storage exceeded 70% for all menthol content levels. In particular, the menthol-containing sheet containing 2.5 times the weight showed a menthol flavor retention rate of approximately 100%.

The ratio of the menthol content in the sheet to the amount of menthol blended in the raw material slurry can be calculated as "menthol yield (%)" using the following formula.

Menthol yield (%)={(measured value of menthol content in sheet)/(menthol compounding amount)}×100.

As shown in Figure 9C , the "Menthol Yield Rate" immediately after sheet production exceeded 50% for samples containing menthol in amounts ranging from 1 to 10 times by weight. The "Menthol Yield Rate" after storage showed the highest value for sheets containing 2.5 times by weight of menthol. Sheets containing 5 or 10 times by weight of menthol had lower "Menthol Yield Rates" after storage than sheets containing 2.5 times by weight of menthol, but the menthol content (absolute amount) in these sheets was higher (see Figure 9A ).

Figures 9D and 9E show the relationship between the menthol blend ratio (%) and the menthol content (%), and the relationship between the menthol blend ratio (%) and the menthol yield (%), respectively. In these figures, the menthol blend ratio (%) is represented by {menthol blend amount/(menthol blend amount + carrageenan blend amount)}×100.

As shown in Figure 9D , sheets containing menthol at a ratio of 2.5 to 10 times by weight (i.e., a menthol ratio of 71 to 91%) exhibited higher menthol content after storage. Furthermore, as shown in Figure 9E , sheets containing menthol at a ratio of 1 to 5 times by weight (i.e., a menthol ratio of 50 to 83%) exhibited higher menthol yields after storage.

As shown in the results of FIG. 9A to FIG. 9E , the amount of menthol blended relative to carrageenan is preferably in the range of 1 to 10 times by weight, and more preferably in the range of 2.5 to 5 times by weight.

(2) Sheets containing gellan gum

As shown in Figure 9F, the "initial menthol content" of gellan gum-containing sheets was highest in sheets containing 5 times the weight of menthol and lowest in sheets containing 0.5 times the weight of menthol. Samples with menthol content ranging from 0.5 to 5 times the weight of menthol varied depending on the menthol content. Regarding the "menthol content after storage," samples with menthol content ranging from 0.5 to 5 times the weight of menthol showed little decrease from the initial menthol content, but samples with menthol content of 10 times the weight of menthol or greater decreased in menthol content with increasing storage days. Consequently, as shown in Figure 9G, the menthol flavor retention rate after 30 days of storage exceeded 90% for samples with menthol content ranging from 0.5 to 5 times the weight of menthol, but was approximately 50% for samples with menthol content of 10 times the weight of menthol or greater. As described above, the samples containing menthol in an amount ranging from 0.5 to 5 times by weight had a high menthol flavor retention rate. In particular, the sheet containing 2.5 times by weight of menthol showed a menthol flavor retention rate of approximately 100%.

As shown in Figure 9H , the "Menthol Yield Rate" immediately after sheet production shows values exceeding 50% for sheets containing 1, 2.5, and 5 times the weight of menthol. The "Menthol Yield Rate" after storage shows the highest value for the sheet containing 2.5 times the weight of menthol. The sheet containing 5 times the weight of menthol has a lower "Menthol Yield Rate" after storage than the sheet containing 2.5 times the weight of menthol, but the menthol content (absolute amount) in the sheet is higher (see Figure 9F ).

Figures 9I and 9J show the relationship between the menthol blend ratio (%) and the menthol content (%), and the relationship between the menthol blend ratio (%) and the menthol yield (%), respectively. In these figures, the menthol blend ratio (%) is represented by {menthol blend amount/(menthol blend amount + gellan gum blend amount)} × 100.

As shown in Figure 9I , sheets containing menthol at a ratio of 2.5 to 5 times by weight (i.e., a menthol ratio of 71 to 83%) exhibited higher menthol content after storage. Furthermore, as shown in Figure 9J , sheets containing menthol at a ratio of 1 to 5 times by weight (i.e., a menthol ratio of 50 to 83%) exhibited higher menthol yields after storage.

As shown in the results of FIG9F to FIG9J , the amount of menthol added to gellan gum is preferably in the range of 1 to 10 times by weight, and more preferably in the range of 2.5 to 5 times by weight.

[Example 12]

In this example, the effect of the amount of lecithin added to the raw material slurry on the menthol content of the menthol-containing sheet after storage was examined.

12-1. Method (Preparation of Sheet and Determination of Menthol Content)

Carrageenan-containing sheets and gellan gum-containing sheets were prepared using the raw material slurry containing lecithin in a certain amount. The sheets were prepared in the same manner as in Example 9.

The carrageenan-containing sheet was blended with lecithin at 0.001, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, and 0.4 times the weight of carrageenan relative to 5% by weight (in the raw material slurry). Menthol was blended at 5 times the weight of the carrageenan.

Similarly, for sheets containing gellan gum, lecithin was blended in amounts of 0.001, 0.005, 0.01, 0.02, 0.05, 0.1, 0.2, and 0.4 times the weight of gellan gum relative to 3% by weight (in the raw material slurry). Menthol was blended in an amount of 5 times the weight of the gellan gum.

The menthol content of the sheet immediately after production (initial menthol content) and the menthol content of the sheet stored under an accelerated environment (menthol content after storage) were measured. The accelerated environment is as described in Example 1. The menthol content was measured using the same method as in Example 1. The results for the sheet containing carrageenan are shown in Figures 10A and 10B, and the results for the sheet containing gellan gum are shown in Figures 10C and 10D. In Figures 10A and 10C, the numerical values in parentheses represent the weight ratio of lecithin to polysaccharides, for example, [0.01] means that the raw material slurry contains 0.01 times the weight of lecithin relative to the polysaccharides. In addition, in Figures 10B and 10D, "immediately after production" means immediately after the sheet is produced, and "50°C·1 month later" means after storage at 50°C for 30 days.

12-2. Results

(1) Sheets containing carrageenan

As shown in FIG10A , in the case of the carrageenan-containing sheet, when the lecithin content was 0.1 to 0.4 times the weight of the carrageenan, the menthol content decreased significantly after storage.

Figure 10B shows the relationship between the amount of lecithin incorporated (weight ratio relative to carrageenan) and the menthol content (%). As shown in Figure 10B , sheets containing lecithin at a weight ratio of 0.005 to 0.02 times the weight of carrageenan retain a high menthol content after storage.

(2) Sheets containing gellan gum

As shown in FIG10C , in the case of the gellan gum-containing sheet, when the lecithin content was 0.1 to 0.4 times by weight relative to the gellan gum, the menthol content decreased significantly after storage.

Figure 10D shows the relationship between the amount of lecithin incorporated (weight ratio relative to gellan gum) and the menthol content (%). As shown in Figure 10D , sheets containing lecithin at a weight ratio of 0.005 to 0.05 times the weight of gellan gum maintain a high menthol content after storage.

As shown in the results of Figures 10A to 10D , the amount of lecithin added to the polysaccharide is preferably in the range of 0.5 to 5% by weight. Specifically, when carrageenan is used as the polysaccharide, the amount of lecithin added to the polysaccharide is preferably in the range of 0.5 to 2% by weight. When gellan gum is used as the polysaccharide, the amount of lecithin added to the polysaccharide is preferably in the range of 0.5 to 5% by weight, and more preferably in the range of 0.5 to 2% by weight.

Example 13

In this example, the effect of the type of emulsifier on the menthol content of a menthol-containing sheet after storage was investigated.

13-1. Method (Preparation of Sheet and Determination of Menthol Content)

Carrageenan-containing sheets and gellan gum-containing sheets were prepared using raw material slurries containing various types of emulsifiers. The sheets were prepared using the same method as in Example 9. Menthol was blended in an amount of 5 times the weight of the polysaccharide, and various emulsifiers were blended in an amount of 0.02 times the weight of the polysaccharide.

The following eight emulsifiers were used as emulsifiers. The numbers 1 to 8 assigned to the emulsifiers correspond to the numbers in Figures 11A and 11B.

1. Lecithin

(Sun Lecithin A-1, Taiyo Chemical Co., Ltd.)

2. Glyceryl fatty acid esters (monoglycerides)

(EXCEL S-95 manufactured by Kao Corporation)

Compound name: Lipophilic monostearate

3. Glyceryl fatty acid esters (polyglycerol esters)

(Sunsoft A-181E manufactured by Taiyo Chemical Co., Ltd.)

Compound Name: Pentaglyceryl Monostearate

4. Glycerol fatty acid esters (organic acid monoglycerides)

(Step SS manufactured by Kao Co., Ltd.)

Compound name: Succinic acid monoglyceride

5. Sorbitan fatty acid esters

(Emasol S-10V manufactured by Kao Corporation)

Compound Name: Sorbitan Monostearate

6. Sorbitan fatty acid esters (polysorbates)

(Emasol S-120V manufactured by Kao Corporation)

Compound Name: Polyoxyethylene sorbitan monostearate

7. Propylene glycol fatty acid esters

(Sunsoft No. 25CD manufactured by Taiyo Chemical Co., Ltd.)

Compound Name: Propylene glycol monostearate

8. Sucrose fatty acid esters

(Ryoto Sugar Ester S-1570 manufactured by Mitsubishi Chemical Foods Co., Ltd.)

Compound Name: Sucrose Stearate

The menthol content of the sheet immediately after production (initial menthol content) and the menthol content of the sheet stored under an accelerated environment (menthol content after storage) were measured. The accelerated environment is as described in Example 1. The menthol content was measured using the same method as in Example 1. The results for the sheet containing carrageenan are shown in FIG11A , and the results for the sheet containing gellan gum are shown in FIG11B . In addition, in FIG11A and FIG11B , "immediately after production" refers to immediately after the sheet is produced, and "50°C·1 month later" refers to after storage at 50°C for 30 days.

13-2. Results

As shown in the results of Figures 11A and 11B, various emulsifiers can be used in addition to lecithin. For sheets containing carrageenan, it is particularly preferred to use 1. lecithin, 3. glycerol fatty acid ester (polyglycerol ester), and 4. glycerol fatty acid ester (monoglyceride of organic acid). For sheets containing gellan gum, it is particularly preferred to use 1. lecithin, 2. glycerol fatty acid ester (monoglyceride), 3. glycerol fatty acid ester (polyglycerol ester), 4. glycerol fatty acid ester (monoglyceride of organic acid), 5. sorbitan fatty acid ester, 7. propylene glycol fatty acid ester, and 8. sucrose fatty acid ester as emulsifiers.

Claims (13)

1. A method for manufacturing a flavored sheet for smoking articles, comprising the following steps: The process of spreading a raw material slurry in a sol state at 60-90°C onto a matrix material, wherein the raw material slurry contains a polysaccharide containing at least one of carrageenan and gellan gum, a fragrance, an emulsifier, and 70-95% by weight of water, and the content of the fragrance based on the polysaccharide is in the range of 100-1000% by weight. The process of cooling the spread raw material slurry to a sample temperature of 0-30°C to gel it; and The heating and drying process includes heating the gelled raw material and drying it at a sample temperature of 70–100°C. 2. The method for manufacturing flavored sheets for smoking articles as described in claim 1, wherein the emulsifier is lecithin at a weight of 0.5 to 5% relative to polysaccharides. 3. The method for manufacturing flavored sheets for smoking articles as described in claim 1, wherein the emulsifier is an ester selected from glycerol fatty acid esters, polyglycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, and sucrose fatty acid esters. 4. The method for manufacturing flavored sheets for smoking articles as described in any one of claims 1 to 3, wherein the concentration of polysaccharides in the raw material slurry is 2 to 6% by weight. 5. The method for manufacturing a flavored sheet for smoking articles according to any one of claims 1 to 3, wherein the flavoring is menthol. 6. The method for manufacturing a flavored sheet for smoking articles as described in claim 4, wherein the flavoring is menthol. 7. The method for manufacturing flavored sheets for smoking articles as described in claim 5, wherein the content of menthol is in the range of 250 to 500% by weight relative to the polysaccharides. 8. The method for manufacturing flavored sheets for smoking articles as described in claim 6, wherein the content of menthol is in the range of 250 to 500% by weight relative to the polysaccharides. 9. A flavored sheet for smoking articles, manufactured by any one of claims 1 to 4. 10. A flavored sheet for smoking articles, manufactured by the method of any one of claims 5 to 8. 11. The flavored sheet for smoking articles as described in claim 10, wherein the menthol content in the manufactured sheet is 45% by weight or more, and the menthol content in the sheet is 45% by weight or more after being stored at 50°C for 30 days. 12. A smoking article comprising tobacco, wherein the tobacco is mixed with a cut of flavored sheet material for a smoking article as described in any one of claims 9 to 11. 13. A cigarette comprising: a cigarette stem containing tobacco and cigarette paper rolled around the tobacco, wherein the tobacco contains a cut of flavored sheet material for smoking articles according to any one of claims 9 to 11.