WO2014102070A1

WO2014102070A1 - Flavor precursors

Info

Publication number: WO2014102070A1
Application number: PCT/EP2013/076515
Authority: WO
Inventors: Felix FRAUENDORFER; Gerhard Lang
Original assignee: Philip Morris Products S.A.
Priority date: 2012-12-28
Filing date: 2013-12-13
Publication date: 2014-07-03
Also published as: TW201429415A; AR094331A1

Abstract

A smoking composition comprises an aerosol-generating substrate and a phenolic glycoside. Cleavage of the glycosidic bond releases a phenolic compound having a smoky note. The smoking composition may be incorporated into a smoking article that is configured to cause the glycosidic bond to be cleaved during use. The smoking article (102) may include tobacco and may be configured to heat, but does not combust, tobacco. Such articles typically are lacking in smoky flavor relative to smoking articles in which tobacco is combusted. Inclusion of the phenolic glycoside helps bridge the flavor gap.

Description

FLAVOR PRECURSORS

This disclosure relates to flavor precursors that can be used in smoking compositions, and articles and methods related to such smoking compositions.

Smoking articles that heat tobacco, without combustion of the tobacco, have been proposed. Such articles generate aerosols that can deliver nicotine and other tobacco constituents to a user. However, because tobacco is not combusted during use of such articles, a user may perceive significantly less smoky notes than is experienced with conventional smoking articles such as cigarettes.

Accordingly, it may be desirable to incorporate compounds into tobacco that is used in non-combustion smoking articles to better approximate an experience associated with smoking a conventional cigarette. A variety of compounds are known to produce smoky notes. However, the volatility of such compounds presents challenges to incorporating the compounds into tobacco or smoking articles. For example, losses may occur during production or storage due to the volatility of the compounds. In addition, an unused article incorporating such compounds may be undesirably perceived as having a burnt or smoky odour.

As described herein, smoking articles, in which the tobacco or other material is heated but not combusted, deliver to a user an aerosol containing a compound of the invention to provide the user with an experience similar to that of smoking a conventional cigarette. The articles contain a smoking composition that includes a phenolic glycoside, which does not produce a significant odour. A glycosidic bond of the phenolic glycoside is cleaved upon heating to produce the phenolic compound which contributes to the smoky note. Thus, a user of the tobacco article may perceive smoky notes similar to that experienced when smoking a conventional cigarette.

Smoking articles described herein may provide one or more advantages to prior smoking articles in which tobacco is not combusted. For example and as described above, the smoking articles described herein provide enhanced flavor or sensory experience relative to smoking articles that do not include a chemically immobilized phenolic compound having a smoky note. Because the phenolic compounds are capable of being disassociated from a glycoside and because the glycosides are not volatile or are less volatile than the phenolic compound, losses during production may be mitigated and the articles may have a longer shelf life. Further, because the glycosides are less odorous than the phenolic compounds, the article does not impart a burnt or smoky note when it is not in use.

For purposes of the present disclosure, the phrase "flavor compound" is used interchangeably with "phenolic compound having a smoky note".

"Smoky", as used herein, is a term readily understood by skilled flavorists as meaning a flavor that is associated with the burning of wood. The term is used in numerous reference books, including "Flavor, Chemistry and Technology", 2^nd Ed., by Gary Reineccius and "Perfume and Flavor Chemicals", 1969, by Steffen Arctander.

Any suitable flavor compound may be conjugated to a reducing sugar to produce a phenolic glycoside, which may be added to tobacco or other material to generate a smoking composition as described herein. Upon cleavage of the glycosidic bond, the phenolic compound having the smoky note is released.

In embodiments, the flavor compound has a structure of the following formula:

Formula I, where R¹, R², R³, R⁴, and R⁵ are each independently selected from the group consisting of (i) H and (ii) C1 -C5 straight or branched chain alkyl or alkoxy, unsubstituted or substituted with halo or hydroxyl. One or more of R¹, R², R³, R⁴, and R⁵ is a C1 -C5 straight or branched chain alkyl or alkoxy. Preferably, the substituted or unsubstituted alkyl or alkoxy is a C1 -C3 alkyl or alkoxy. Preferably, the alkyl or alkoxy is unsubstituted.

In embodiments, one or more of R¹, R², R³, R⁴, and R⁵ are selected from the group consisting of methyl, ethyl, propyl (such as isopropyl), methoxy, and ethoxy. Preferably, one or more of R¹, R², R³, R⁴, and R⁵ are selected from the group consisting of methyl, ethyl, isopropyl, and methoxy. In some embodiments, those of R¹, R², R³, R⁴, and R⁵ that are not methyl, ethyl, propyl, methoxy, or ethoxy are H.

In embodiments, one or both of R¹ and R⁵ are methoxy.

In embodiments, R³ is isopropyl.

In embodiments, one or more of R¹, R², and R³ are methyl.

In embodiments, R² is ethyl.

Preferred flavor compounds include those selected from the group consisting of 2- methoxyphenol (or guaiacol where R¹ of Formula I is methoxy, and R², R³, R⁴, and R⁵ are H), 2,6-dimethoxyphenol (where R¹ and R⁵ of Formula I are methoxy, and R², R³, and R⁴ are H), o- cresol (where R¹ of Formula I is methyl, and R², R³, R⁴, and R⁵ are H), m-cresol (where R² of Formula I is methyl, and R¹, R³, R⁴, and R⁵ are H), p-cresol (where R³ of Formula I is methyl, and R¹, R², R⁴, and R⁵ are H), 3-ethylphenol (where R² of Formula I is ethyl, and R¹, R³, R⁴, and R⁵ are H), 4-isopropylphenol (where R³ of Formula I is isopropyl, and R¹, R², R⁴, and R⁵ are H), and 2,3-dimethylphenol (where R¹ and R² of Formula I are methyl, and R³, R⁴, and R⁵ are H).

More preferably, the flavor compound is guaiacol (2-methoxyphenol).

In accordance with the teachings presented herein, any flavor compound may be released from a glycoside. As used herein, a flavor compound is an aromatic six carbon- membered ring structure in which at least one of the carbons of the ring has a hydroxyl group substituent. The other ring-members may be substituted or unsubstituted, provided that the compound produces a smoky note.

Any suitable test may be employed to determine whether the flavor compound produces a smoky note. For example, a compound that invokes a subjective perception of a smoky note, odour, smell, flavor, or the like is considered to have or produce a smoky note. In embodiments, people trained in the art of odour perception may be used to determine whether a phenolic compound has a smoky note. In embodiments, randomly or non-randomly selected people may be used to determine whether they perceive the compound to produce a smoky note. By way of example, if 25% or more (e.g., 50% or more, 60% or more, 70% or more, or 80% or more) of the selected people perceive a smoky note or if a panel use descriptors relating to a smoky note (e.g., smoky), the compound will be determined to have a smoky note.

A flavor compound, or a derivative thereof, may be conjugated to any suitable reducing sugar

(also referred to as a glycone) via a glycosidic bond to produce a glycoside that will release the phenolic compound upon cleavage of the glycosidic bond. The glycone may be any suitable monosaccharide or polysaccharide or a derivative thereof. By way of example, the polysaccharide may be cellulose, a trisaccharide or a disaccharide. Examples of trisaccharides that may serve as the glycone include isomaltrotriose, nigerotriose, maltotriose, melezitose, maltrotriulose, raffinose, kestose, and the like. Examples of disaccharides that may serve as the glycone include sucrose, maltose, lactose, cellobiose, lactulose, trehaolse, kojibiose, nigerose, isomaltose, β,β-trehalose, α,β-trehalose, sophorose, laminaribiose, gentiobiose, turanose, maltulose, palatinose, gentiobiulose, mannobiose, melibiose, melibiulose, rutinose, rutinulose, xylobiose, and the like.

If a monosaccharide is the glycone, the monosaccharide is preferably a C5-C7 monosaccharide. More preferably the monosaccharide is a C6 monosaccharide. Examples of monosaccharides that may serve as the glycone include glucose, galactose, glucuronic acid, fructose, xylose, ribose, mannose, arabinose, maltose, tagatose, and the like. Preferably, the monosaccharide is glucose.

Glycosides may be synthesized in any suitable manner. An example of a glysosylation reaction is the Koenigs-Knorr reaction, which is a substitution reaction of a glycosyl halide with an alcohol in the presence of a heavy metal or silver salt to yield a glycoside. Other glycosylation methods that may be employed are Helferich glycosylation, where the catalyst is a mercury salt such as mercuric cyanide; Fischer glycosidation; use of glycosyl acetates; glycosyltrichloroacetimidat.es; glycosyl fluorides; intramolecular aglycon delivery; or the like.

In embodiments, glycosylation reactions as described in, for example, (i) Dignum et al. (2004) Food Chemistry 85:199-205; (ii) Hayasaka et al. (2010) J. Agric. Food Chem. 58:10989- 10998; (iii) Cai et al. (2010) Asian J. Chem. (2010) 22(9):6647-6651 ; or (iv) WO 88/09133 may be employed or modified to produce a phenolic glycoside.

Glycoslyation reactions often include reacting a glycosyl donor with a glycosyl acceptor, which in the present disclosure is the phenolic compound or a derivative thereof, in the presence of a catalyst to produce a phenolic glycoside. A free alcohol of the phenolic compound or derivative thereof will react with the glycosyl donor to produce an O-glycosidic linkage. Any suitable glycosyl donor may be used. Often the glycosyl donor is a glycoyl halide, such as a glycoyl bromide, a glycoyl chloride, or the like.

2,3,4,6-Tetraacetyl-a-D-glycopyranosyl bromide ("acetobromoglucose") is commonly used for preparing glycosides derived from glucose. The preparation of acetobromoglucose commonly involves the peracerylation of glucose with acetic anhydride in the presence of a catalyst, such as pyridine, triethyl amine and dimethylaminopyridine, or sodium acetate and zinc chloride, in a solvent such as dichloromethane. The resulting 1 ,2,3,4, 6-Pentaacetyl-a-p-D- glucopyranoside may be treated with HBr-acetic acid in, for example, dichloromethane to produce acetobromoglucose, which may be obtained by crystallization. The chloro derivative may be obtained by using HCI steam, SOCI₂ in dimethylformamide ("DMF"), or the like.

If the sugar contains acid sensitive groups such as azide or acid-sensitive protecting groups such as acetonide or benzylidine, more mild conditions for halogenation, such as fosgene in DMF or bromotrimethlysilane, may be used to generate the glycoyl halide.

Acetobromoglucose (CAS Number 572-09-8) may be synthesized as described above or purchased from a commercial vendor such as Sigma-Aldrich. The reactions described above regarding acetobromoglucose may be readily modified to produce pivaloylbromoglucose (CAS Number 81058-27-7). Alternatively, pivaloylbromoglucose may be purchased from a commercial vendor such as Sigma-Aldrich.

For purposes of example, a glycoside having glucose, or a derivative thereof, as the glycone and a flavor compound as the aglycone is depicted below in Formula II:

Formula II, where R¹, R², R³, R⁴, and R⁵ are as described above with regard to Formula I, and wherein R⁶, R⁷, R⁸ and R⁹ are independently H or a protecting group such as acetyl [-C(0)CH₃]; pivaloyl [-C(0)(CH₃)₃; also known as trimethyl acetyl or 2,2-dimethyl propanoyl]; or the like. In embodiments, R⁶, R⁷, R⁸ and R⁹ are the same. Preferably, R⁶, R⁷, R⁸ and R⁹ are H. If R⁶, R⁷, R⁸ or R⁹ is a protecting group, the protecting group may be cleaved to produce a phenolic glycoside having an unsubstituted glycone. By way of example, cleavage of acetyl or pivaloyl groups readily occurs in sodium methoxide-methanol (NaOMe-MeOH). Other protecting groups may readily be removed via any suitable deprotection reaction, many of which are well-known in the art. It will be understood that the glycone may be derived from any suitable monosaccharide other than glucose as depicted in Formula II or from a suitable polysaccharide, such as those described above.

In a preferred embodiment, the glycoside is guaiacol glucoside ((2R,3S,4S,5R,6S)-2- hydroxymethyl)-6-(2-methoxyphenoxy)tetrahydro-2H-pyran-3,4,5-triol), which has a structure of the following formula:

As used herein, a flavor composition is a composition comprising a phenolic glycoside. The term "phenolic glycoside" is used interchangeably herein with "flavor precursor compound". A flavor delivery composition of the invention comprises a flavor precursor compound and facilitates the release of the flavor precursor compound to its surrounding environment in a controlled manner. In various embodiments, the phenolic glycoside is synthesized or purified prior to its addition to the flavor composition or flavor delivery composition.

A phenolic glycoside, as described above, may be included in a smoking composition in any suitable manner and in any suitable amount. The term "smoking composition" is used to describe a composition that produces smoke when it is combusted or heated, and is used to make a smoking article. The term "smoking article" includes cigarettes, cigars, cigarillos and other articles in which a smoking composition, such as a tobacco composition, is lit and combusted to produce smoke. The term "smoking article" also includes those in which the smoking composition is not combusted such as but not limited to smoking articles that heat the smoking composition directly or indirectly, without burning or combusting the smoking composition, or smoking articles that neither combust nor heat the smoking composition, but rather use air flow or a chemical reaction to deliver nicotine, flavor compound or other materials from the tobacco. As used herein, the term "smoke" is used to describe an aerosol produced by combusting a smoking article. An aerosol produced by a smoking article may be, for example, smoke produced by combustible smoking articles, such as cigarettes, or aerosols produced by non-combustible smoking articles, such as heated smoking articles or non-heated smoking articles.

A flavor composition of the invention can comprise, in addition to the flavor precursor compound, one or more flavorants known in the art, which include but are not limited to, menthol, spearmint, peppermint, eucalyptus, vanilla, cocoa, chocolate, coffee, tea, spices (such as cinnamon, clove and ginger), fruit extracts, and combinations thereof. In embodiments, the flavor composition further comprises menthol or eugenol. Such flavorants are commonly used to provide a refreshing flavor to the smoke of a smoking article.

A flavor delivery composition can controllably release a flavor precursor compound to its surrounding environment by any suitable methods, for example by deformation of the flavor delivery composition or by changing the temperature. The amount of flavor precursor compound released over a time interval, as well as the start or end of the interval(s) can be controlled. The amount of flavor precursor compound released during each interval and the length of time intervals need not be equal.

In embodiments, a flavor delivery composition may take any suitable form which is capable of retaining the flavor composition within the structure of the composition until the release is desired. Preferably, the flavor delivery composition comprises a closed matrix or network structure, which traps the flavor precursor compound within the closed structure. For example, the flavor composition may be trapped in domains within a matrix structure. Upon compression or deformation of the material, the flavor precursor composition is forced out from the matrix structure, for example, through the breakage of the surrounding structure. In embodiments, the flavor delivery composition comprises a polymer matrix comprising one or more matrix-forming polymers. For example, the gradual breakdown of the polymer matrix with increasing compressive force, temperature, or both provides the controlled release of the flavor precursor compound from the flavor delivery composition. The release of the flavor precursor compound can thus vary as a function of temperature or the deformation resulting from the compressive or shear force that is applied to the flavor delivery composition. The flavor delivery composition may advantageously be provided within smoking articles in a variety of different forms so that there is flexibility in the way in which the composition can be incorporated into the smoking article. In embodiments the flavor delivery composition is provided in the form of particles, beads or capsules. The particles, beads or capsules may be formed into any suitable shape, but are preferably substantially cylindrical or spherical.

A smoking composition of the invention comprises a flavor precursor compound, a flavor composition or a flavor delivery composition. A smoking composition may comprise, for example, one or more of: powder, granules, pellets, shreds, strips or sheets comprising one or more of: herb leaf, tobacco leaf, tobacco stems, fragments of tobacco ribs, homogenized tobacco, reconstituted tobacco, processed tobacco, extruded tobacco and expanded tobacco. The smoking composition may be in loose form, or may be provided in a suitable container or cartridge. For example, the smoking composition may be contained within a paper or wrap and have the form of a plug.

Smoking articles that include aerosol-generating devices typically comprise an aerosol- generating substrate that is assembled, often with other components, in the form of a rod. Typically, such a rod is configured in shape and size to be inserted into an aerosol-generating device that comprises a heating element for heating the aerosol-generating substrate. "Aerosol- generating substrate" as used herein is a type of smoking composition that can be used in an aerosol-generating device to produce an aerosol. The aerosol-generating substrate can release a flavor compound upon combustion or heating. The aerosol-generating substrate can be in solid form or liquid form. The substrate can comprise both liquid and solid components. The aerosol-generating substrate may comprise tobacco and a flavor composition wherein a flavor precursor compound or a disassociated flavor compound is released from the substrate upon heating. In embodiments, the aerosol-generating substrate does not include tobacco, but does include a flavor composition wherein a phenolic glycoside as described herein or a disassociated flavor compound is released from the substrate upon heating, and optionally nicotine. The aerosol-generating substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerine and propylene glycol. Optionally, the aerosol- generating substrate may be provided on or embedded in a carrier which may take the form of powder, granules, pellets, shreds, spaghetti strands, strips or sheets. The aerosol-generating substrate may be deposited on the surface of the carrier in the form of, for example, a sheet, foam, gel or slurry. The aerosol-generating substrate may be deposited on the entire surface of the carrier, or alternatively, may be deposited in a pattern in order to provide a non-uniform flavor delivery during use.

Smoking articles may comprise a filter which may be a single segment filter or a multi- component filter comprising two or more connected or unconnected filter segments. A variety of suitable filter segments would be known to the skilled person. One or more of the filter segments may each comprise a flavor precursor compound, a flavor composition or a flavor delivery composition. Smoking articles may be packaged in containers for sale, for example in soft packs or hinge-lid packs, with an inner liner coated or impregnated with a flavor compound, a flavor composition or a flavor delivery composition.

A smoking composition comprising a flavor precursor compound, a flavor composition or a flavor delivery composition can be manufactured using any suitable technique. For example, the flavor precursor compound may be added to cut filler tobacco stock supplied to a cigarette- making machine or applied to a pre-formed tobacco column prior to wrapping a cigarette wrapper around the tobacco column. In embodiments, a method for manufacturing the smoking composition comprises the step of spraying tobacco with a flavor precursor compound. To facilitate spraying, the flavor precursor compound can be added to a liquid carrier to form a solution or a suspension, and the solution or suspension can be applied onto the tobacco. The smoking composition can then be processed for use in a cigarette or other smoking article. Solutions or suspensions comprising the flavor precursor compound can include any liquid or liquid mixtures suitable for dispersing and dispensing (e.g., spraying) particles comprising the flavor precursor compound. A preferred liquid is water (e.g., deionized water), though other liquids, such as alcohols, can be used.

The concentration of a flavor precursor compound in the slurry can be any amount suitable for dispensing the solution or suspension onto tobacco. Such solution or suspension comprising a dispersion of a flavor precursor compound in a liquid can comprise about 0.1 % and up to less than about 0.5%, or about 0.2% and up to less than about 1 % by weight of a flavor precursor compound. The flavor precursor compound can be provided in the form of a dried powder and applied to tobacco as such. If dried powder is used, it can be dusted onto tobacco. Another technique for incorporating the flavor precursor compound in a tobacco smoking composition involves adding the flavor precursor compound to a slurry of ingredients used to make reconstituted tobacco. The slurry, including the flavor precursor compound, can be formed into a reconstituted tobacco sheet and the sheet can be cut to shreds for incorporation as cut filler of a rod of smoking composition or other forms of smoking article.

Homogenized tobacco can also be used to make aerosol-generating substrate for use in smoking articles that are being heated in an aerosol-generating device. As used herein, the term "homogenized tobacco" denotes a material formed by agglomerating particulate tobacco. Tobacco dust created by tobacco breakage during shipping and manufacturing, leaf lamina, stems and other tobacco by-products that are finely ground may be mixed with a binder to agglomerate the particulate tobacco. Homogenized tobacco may comprise other additives in addition to a flavor composition or a flavor delivery composition, including but not limited to, aerosol-formers, plasticisers, humectants, and non-tobacco fibres, fillers, aqueous and nonaqueous solvents and combinations thereof. Homogenized tobacco can be cast, extruded, or rolled. A number of reconstitution processes for producing homogenized tobacco materials are known in the art. These include, but are not limited to: paper-making processes of the type described in, for example, US5,724,998; casting processes of the type described in, for example, US5,724,998; dough reconstitution processes of the type described in, for example, US3,894,544; and extrusion processes of the type described in, for example, in GB983,928.

It will be appreciated that aerosol-generating substrates may have different shapes and sizes depending upon, for example, the type of smoking article in which they are intended to be used. Aerosol-generating substrates may be substantially three-dimensional. For example, aerosol-generating substrates may be bricks or plugs comprising a plurality of strands of homogenized tobacco material according to the invention. Alternatively, aerosol-generating substrates may be substantially two-dimensional. For example, aerosol-generating substrates according to the invention may be mats or sheets comprising a plurality of strands of homogenized tobacco.

The amount of flavor precursor compound desired in a smoking composition may vary depending on the final product in which the smoking composition is to be included. For example, the phenolic glycoside may be added to tobacco to enhance the smoky flavor or aroma of conventional smoking articles, such as cigarettes, cigars, and the like. As such articles may already produce a smoky flavor or aroma when smoked, phenolic compounds described herein may be added in relatively low concentrations or amounts. In contrast, it may be desirable to add higher concentrations or amounts of phenolic glycosides to smoking compositions, such as tobacco-containing aerosol-generating substrates, that will be used in smoking articles in which constituents are aerosolized or heated without combustion. Smoking articles having aerosol-generating substrates that contain tobacco and that are used with an aerosol-generating device typically provide less intense flavors or aromas to a user when compared to a conventional cigarette. It may also be desirable to include higher concentrations or amounts of phenolic glycosides to smoking compositions that do not include tobacco, such as non-tobacco containing aerosol-generating substrates. Preferably, the phenolic glycosides are included in the smoking composition for use in smoking articles in amounts that provide a user with a perceived intensity similar to a conventional smoking article, such as a cigarette. For example, the phenolic glycoside may be included in a non-combustion smoking article or a smoking article that does not include tobacco in an amount that results in the release or delivery of the phenolic compound in a concentration or amount similar to that delivered to a user of a conventional smoking article such as a cigarette.

In embodiments, the amount of phenolic flavor compound delivered to a user may be determined on a per puff basis. Any suitable method may be used to determine the amount of flavor compound delivered per puff. For example, ISO, Health Canada Intense, or other standard or automated procedures may be employed or modified to determine content per puff. Examples of ISO methods that may be employed or modified include: (i) ISO 4387:1991 Cigarettes - Determination of total and nicotine free dry matter using a routine analytical smoking machine, 1991 -10-15; (ii) ISO 8454:1995 Cigarettes - Determination of carbon monoxide in the vapour phase of cigarette smoke - NDIR method, 1991 -1 1 -15; (iii) ISO 10315:1991 Cigarettes - Determination of nicotine in smoke condensates - Gas- chromatographic method, 1991 -08-01 ; and (iv) ISO 10362-1 :1991 Cigarettes - Determination of water in smoke condensates - Part 1 : Gas-chromatographic method, 1991 -09-15. The Health Canada Intensive method refers to: Health Canada - Official Method T-1 15, Determination of "Tar", Nicotine and Carbon Monoxide in Mainstream Tobacco Smoke, December 1999. Regardless of the method employed, it may be desirable to determine the amount of a flavor compound that is delivered per puff of a conventional cigarette and formulate a non- conventional smoking article that aerosolizes tobacco or other constituents without combustion so that it delivers similar amounts of the flavor compound per puff. The amount of phenolic glycoside added to a smoking composition for such articles may be varied and tested to determine how much phenolic glycoside is needed to deliver a similar amount of the flavor compound.

By way of example and as discussed in more detail below, it has been found that guaiacol is delivered to a smoker of a conventional cigarette in an amount from about 100 nanograms per puff to about 300 nanograms per puff when using the Health Canada Intensive method. Accordingly, it may be desirable for a non-conventional smoking articles, such as those that aerosolize tobacco constituents or other constituents without combustion, to include an amount of a phenolic glycoside that results in delivery of 50 nanograms of guaiacol per puff or greater, such as from about 50 nanograms of guaiacol to about 500 nanograms of guaiacol per puff or from about 100 nanograms of guaiacol per puff to about 300 nanograms of guaiacol per puff.

Of course, the desired amount of flavor compound delivered per puff will depend on the flavor compound itself. In embodiments, a smoking article is configured to deliver about 5 nanograms or greater of the flavor compound per puff. In embodiments, a smoking article is configured to deliver from about 10 nanograms of the flavor compound per puff to 1 milligram of the flavor compound per puff, such as from about 50 ng/puff to about 750 ng/puff or from about 75 ng/puff to about 500 ng/puff.

The amount of flavor precursor compound added to a smoking composition to deliver a desired amount of disassociated flavor compound to a user will depend on the components and configuration of the article and the phenolic glycoside.

Of course, a phenolic glycoside may be added to a smoking composition in any suitable amount or concentration. In embodiments, a smoking composition includes from about 0.001 weight %, more preferably from about 0.005 weight %, even more preferably from about 0.01 weight % of phenolic glycoside. In embodiments, a smoking composition includes up to about 2 weight % of the phenolic glycoside, even more preferably up to about 1 weight % of the phenolic glycoside, even more preferably up to about 0.5 weight % of the phenolic glycoside, and even more preferably up to about 0.02 weight % of the phenolic glycoside (all weight % referring to dry weight).

One or more of the added phenolic glycosides may be naturally present in cured or uncured tobacco. By way of example, it has been found that guaiacol glucoside [((2R,3S,4S,5R,6S)-2-(hydroxymethyl)-6-(2-methoxyphenoxy)tetrahydro-2H-pyran-3,4,5-triol)] is present in tobacco. Accordingly, the addition of a synthesized or purified phenolic glycoside to tobacco will increase the concentration of phenolic glycoside in a smoking composition comprising tobacco relative to the tobacco alone. In embodiments, a synthesized or purified phenolic glycoside is added to tobacco to form a smoking composition having a concentration of the phenolic glycoside that is 1 .5 times or more than the concentration in tobacco alone. For example, the concentration of the phenolic glycoside in the smoking composition may be 2 times or more, 2.5 times or more, 3 times or more, 3.5 times or more, 4 times or more, 4.5 times or more, 5 times or more, 7.5 times or more, or 10 times or more than the concentration in tobacco alone.

One or more flavor precursor may be added to a smoking composition in any suitable manner. For example, a flavor composition comprising a flavor precursor compound, in the form of a solution, suspension or dispersion may be sprayed on tobacco; tobacco may be dipped in a phenolic glycoside solution, suspension or dispersion, phenolic glycoside powder or crystals may be added to tobacco; or the like. The flavor precursor compound may be added to tobacco at any suitable time, such as before or during processing of the tobacco for incorporation into a smoking article or the like. Preferably the glycoside is stable (that is, the glycosidic bond is not cleaved) under such processing.

By way of example, the reconstitution of tobacco can be performed by drying and casting homogeneous slurry of tobacco powder, water, glycerine, guar and cellulose fibers. This type of process is known as cast leaf process and is widely used by the tobacco industry for the manufacturing of reconstituted or homogenized tobacco for use in conventional cigarette. A cast leaf process may involve applying temperatures of below 200°C, below 150°C, or in the range of about 100 to 150°C, or 100 to 200°C. Accordingly, if the smoking composition that includes the flavor precursor compound is to be manufactured in a cast leaf process, the flavor precursor compound is preferably stable at such temperatures.

Preferably, the glycosidic bond of the flavor precursor compound undergoes cleavage under general use conditions of the article in which the smoking composition is incorporated. By way of example, smoking articles that heat, but do not combust, tobacco to aerosolize tobacco constituents typically heat the tobacco at about 200°C to about 300°C. Accordingly, the glycosidic bond of the flavor precursor compound is preferably cleaved at a temperature below about 200°C to about 300°C when a smoking composition having the glycoside is included in such articles. By way of another example, combustion of tobacco typically occurs at a temperature of about 400°C. Accordingly, the glycosidic bond of the flavor precursor compound is preferably cleaved at a temperature below about 400°C when a tobacco composition having the glycoside is included in conventional smoking articles such as cigarette or cigars.

In embodiments, the glycosidic bond of the flavor precursor compound is cleaved at a temperature of about 150°C or greater to release the flavor compound of the invention. In embodiments, the glycosidic bond of the flavor precursor compound is cleaved at a temperature of about 400°C or less. In embodiments, the glycosidic bond of the flavor precursor compound is cleaved at a temperature of from about 100°C to about 400°C, such as from about 150°C to about 300°C or from about 200°C to about 300°C.

Tobacco compositions, as used herein refer to smoking compositions that include tobacco and flavor precursor compound and they may be used to make any suitable smoking article product for which an enhanced smoky note is desired. For example, the tobacco composition may be used in conventional smoking articles or smoking articles in which an aerosol-generating substrate is used. The tobacco composition can be reconstituted tobacco containing various tobacco types of different origins, as well as binders and humectants. The humectants facilitate the production of an aerosol. When heated, the humectants evaporate and re-condense into small droplets to generate a visible aerosol. Preferably, the glycosidic bond of the flavor precursor composition is cleaved under use conditions, but not under storage, processing, or manufacturing conditions.

In the case of combustible smoking articles such as cigarettes, the smoking composition may be used in any portion of the smoking article having a tobacco substrate, for example in the tobacco rod of a conventional cigarette, or in one or more segments of the filter of a conventional cigarette. In the case of smoking articles in which the smoking composition, or a component thereof, is not combusted, the smoking composition may be used in any portion of the smoking article having an aerosol-generating substrate. By way of example and with reference to FIG. 1 , a schematic drawing of a non-limiting smoking article 102 in which the smoking composition is not combusted is shown. As shown in FIG. 1 , the smoking article 102 includes a combustible heat source 104, an aerosol-generating substrate 106, an elongate expansion chamber 108 and a mouthpiece 110 in abutting coaxial alignment, which are overwrapped in an outer wrapper of cigarette paper 112 of low air permeability.

The combustible heat-source 104 is a pyrolised porous carbon-based heat source. The combustible heat source 104 is cylindrical and comprises a central airflow channel 116 that extends longitudinally through the combustible heat source 104. A substantially air impermeable, heat resistant coating 114 of iron oxide is provided on the inner surface of the central airflow channel 116. The aerosol-generating substrate 106 is located immediately downstream of the combustible heat source 104 and comprises a cylindrical plug of homogenized tobacco material 118 comprising a flavor precursor compound and glycerine as aerosol former and circumscribed by plug wrap 120. The homogenized tobacco material 118 consists of longitudinally aligned filaments of extruded tobacco material.

A heat-conducting element 122 consisting of a tube of aluminum foil surrounds and is in contact with a rear portion of the combustible heat source 104 and an abutting front portion of the aerosol-generating substrate 106. As shown in FIG. 1 , a rear portion of the aerosol- generating substrate 106 is not surrounded by the heat-conducting element 122.

The elongate expansion chamber 108 is located downstream of the aerosol-generating substrate 106 and comprises a cylindrical open-ended tube of cardboard 124. The mouthpiece 110 of the smoking article 102 is located downstream of the expansion chamber 108 and comprises a cylindrical plug of cellulose acetate tow 126 of very low filtration efficiency circumscribed by filter plug wrap 128. The mouthpiece 110 may be circumscribed by tipping paper (not shown). The dimensions of the smoking article 102 may be similar to a conventional cigarette.

In use, a user ignites the combustible carbon-based heat source 4 and then draws air through the central airflow channel 116 downstream towards the mouthpiece 110. The front portion of the aerosol-generating substrate 106 is heated primarily by conduction through the abutting non-combusting rear portion of the combustible heat source 104 and the heat- conducting element 122. The drawn air is heated as it passes through the central airflow channel 116 and then heats the aerosol-generating substrate 106 by convection. The heating of the aerosol-generating substrate 106 releases volatile and semi-volatile compounds, including the disassociated flavor compound, and glycerine from the aerosol forming substrate 118, which are entrained in the heated drawn air as it flows through the aerosol-generating substrate. The heated air and entrained compounds pass downstream through the expansion chamber 108, cool and condense to form an aerosol that passes through the mouthpiece into the mouth of the user (at about ambient temperature).

To make the smoking article 102, a rectangular piece of the heat-conducting element 122 is glued to cigarette paper 112. The heat source 104, the plug of the aerosol-generating substrate 106 and the expansion chamber 108 are suitably aligned and positioned on the cigarette paper 112 with the attached heat-conducting element 122. The cigarette paper 112 with the attached heat-conducting element 122 is wrapped around the rear portion of the heat source 104, the aerosol-generating substrate 106 and the expansion chamber 108 and glued. The mouthpiece 110 is attached to the open end of the expansion chamber using known filter combining technology.

In another example of a heated smoking article, the smoking composition comprising the flavor precursor compound is brought into direct contact with a heat source that is not combusted, such as an electrical heat source. FIG. 2 shows a smoking article that is heated by an electrical heat source when engaged with a device for consumption. The smoking article 101 comprises a front-plug 103, an aerosol-generating substrate 111 , a hollow cellulose acetate tube 109, a transfer section 107, and a mouthpiece filter 105. These five elements are arranged sequentially and in coaxial alignment and are assembled by a cigarette paper 5 to form a rod. The rod has a mouth-end, which a user inserts into his or her mouth during use, and a distal end located at the opposite end of the rod to the mouth end. When assembled, the rod 15 is 52 millimetres long and has a diameter of 7.2 millimetres. The front-plug 103 is a cylindrical portion of cellulose acetate tow. The aerosol-generating substrate 111 is located downstream of the front-plug 103 and comprises a bundle of crimped cast-leaf tobacco wrapped in a filter paper. The cast-leaf tobacco includes additives, including glycerine as an aerosol former. The tube 109 is located immediately downstream of the aerosol-generating substrate 111 and is formed from cellulose acetate. The transfer section 107 allows volatile substances including the flavor compound released from the aerosol-generating substrate 111 to pass along the rod towards the mouth end. The volatile substances may cool within the transfer section 107 to form an aerosol. The mouthpiece filter 105 is a conventional mouthpiece filter formed from cellulose acetate tow. The elements identified above are assembled by being tightly wrapped within a cigarette paper 115.

The aerosol-generating device 119 comprises a sheath 121 for receiving the smoking article 101 for consumption. A heating element 113 is located within the sheath 121 and positioned to engage with the distal end of the smoking article 101. The heating element 113 is shaped in the form of a blade terminating in a point. As the smoking article 101 is pushed into the sheath the point of the heating element 113 engages first with the front-plug 103 and then penetrates into the aerosol-generating substrate 111. When the smoking article 101 is properly engaged with the aerosol-generating device 119, the heating element 113 is located within the aerosol-generating substrate 111. Heat generated by the heating element 113 is transferred by conduction and convection to the aerosol-generating substrate 111 which comprises the flavor precursor compound. An insulating collar 117 may surround a portion of the heating element 113 that is in contact with and protect the front-plug 103 from burning or melting. Of course, it will be understood that the smoking articles described with regard to FIG. 1 and FIG. 2 are just two examples of a smoking article that may employ a smoking composition comprising a flavor precursor compound as described herein. It will be further understood that methods for making a smoking article having a smoking composition that includes a flavor precursor compound other than those described in connection with FIG. 1 and FIG. 2 may be employed.

Any suitable method for making a smoking article having a smoking composition that includes a flavor precursor compound may be employed. In general, a method for making a smoking article having a smoking composition that includes a flavor precursor compound includes adding or incorporating the flavor precursor compound or a flavor delivery composition into a smoking composition, such as tobacco or other substrate; and incorporating the smoking composition into a smoking article.

In general and as described herein, a method for enhancing smoky odour or note of a smoking composition comprises adding or a flavor precursor compound or a flavor delivery composition to the smoking composition. A glycosidic bond of the flavor precursor compound is hydrolyzed upon heating to cause dissociation of a flavor compound. The heating of the flavor precursor compound occurs when a smoking article is used (combusted or heated) by a smoker.

All scientific and technical terms used herein have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein.

As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise.

As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

As used herein, "have", "having", "include", "including", "comprise", "comprising" or the like are used in their open ended sense, and generally mean "including, but not limited to". It will be understood that "consisting essentially of", "consisting of", and the like are subsumed in "comprising," and the like.

Non-limiting examples illustrating certain aspects of the compounds, compositions, processes and articles described in this disclosure are provided below. Examples

Example 1 : Evaluation of compounds with smoky notes

Forty-five compounds described in the literature and other sources were identified as candidates for having smoky odour qualities. Some of the compounds were tested by a sensory panel and comparisons of smoky notes were made relative to guaiacol, which was determined to most accurately trigger a smoky sensation. While some of the other compounds elicited perceptions of smoky notes, additional notes that interfered or undercut the smoky notes were present. For example, 2-methoxythiophenol has a somewhat smoky odour quality, but also has a more dominant meaty note. Many of the other compounds were determined to not have elicited a smoky perception.

While guaiacol is a leading example, other phenolic compounds with a similarly desirable smoky odour quality were identified. These compounds include 2,6-dimethoxyphenol (CAS 91 -10-1 ); ortho-, meta- or para-cresol; 3-ethylphenol (CAS 123-07-9), 4-isopropylphenol (CAS 99-89-8); and 2,3-dimethylphenol (CAS 526-75-0).

Example 2: Release of guaiacol from guaiacol glucoside in a smoking article

The glucoside of guaiacol ((2R,3S,4S,5R,6S)-2-(hydroxymethyl)-6-(2- methoxyphenoxy)tetrahydro-2H-pyran-3,4,5-triol) was synthesized, and initial tests with a thermal desorber showed that it releases guaiacol upon heating. As shown in FIG. 3, which shows detection of ions for guaiacol (among other things) as guaiacol glucoside was heated in a thermal desorber, the onset temperature for the release of guaiacol from the glucoside is about 222°C. Such a release temperature is well suited for use in smoking articles that heat, but do not combust, tobacco to increase the smoky note in aerosol produced by such articles.

As also shown in FIG. 3, lower amounts of acetic acid ions were detected at an onset temperature of about 250°C.

Next, tobacco was spiked with various concentrations of guaiacol glucoside. Plugs of the spiked tobacco were included in smoking articles that heat but do not combust tobacco. A first smoking article included a first blend of tobacco (Blend A, without heat exchanger), and a second smoking article included a second blend of tobacco (Blend B, with heat exchanger).

The articles were smoked under the Health Canada Intensive method and the aerosol collected in a cold trap over 12 puffs. The guaiacol concentration of the trapped aerosol has been determined by applying a Stable Isotope Dilution Assay (SI DA). The results are presented in FIG. 4.

As shown in FIG. 4, guaiacol-glucoside delivers high yields of guaiacol upon heating by electrical means in the tobacco in the first smoking article (Blend A, without heat exchanger, HX), (upper curves in FIG. 4). The addition of 1 mg of guaiacol glucoside onto a the first smoking article resulted in a guaiacol release of more than 3000 ng/puff which is more than 10 fold the concentration of guaiacol that is observed in a commercially available brand of conventional cigarette (not shown in FIG. 4). Also the second smoking article (Blend B, with heat exchanger, HX) (lower, green curves in FIG. 4) show an increased release of guaiacol relative to the commercially available brand of conventional cigarette, but considerably lower than the smoking article without a heat exchanger. From previous experiments, it is known that compounds with hydroxyl groups, and in particular phenolic compounds (like guaiacol), are trapped by the heat exchanger.

Transformation yields were then calculated taking into account the amount of guaiacol delivered in 12 puffs under a Health Canada Intensive smoking regime in relation to the initial amount of spiked precursor per plug (in mol %). While the transformation yield for the smoking article without the heat exchanger is about 10 mol%, it is only 1 mol% in the smoking articles with the heat exchanger. However, the target concentration of guaiacol (150-250 ng/puff, which was observed with the commercially available brand of conventional cigarette) can still be achieved with relatively low amounts of guaiacol glucoside added.

As only part of the tobacco is heated and as only part of the precursor is degraded within twelve puffs, transformation yields were significantly below 100%. The results are presented below in Table 1.

Table 1 : Transformation yields of guaiacol-glycoside to guaiacol

^* Relation between the concentration in the aerosol (sum of 12 puffs/smoking article) and the amount spiked per plug in molar units. The plug included 280 mg tobacco.

Claims

1 . A smoking composition comprising:

a chemically synthesized phenolic glycoside compound, wherein cleavage of a glycosidic bond of the phenolic glycoside results in the release of a phenolic compound having the structure:

where R¹, R², R³, R⁴, and R⁵ are each independently selected from the group consisting of (i) H and (ii) C1 -C5 straight or branched chain alkyl or alkoxy, wherein the alkyl or alkoxy is unsubstituted or substituted with halo or hydroxyl,

wherein one or more of R¹, R², R³, R⁴, and R⁵ is a C1 -C5 straight or branched chain alkyl or alkoxy,

wherein the phenolic compound has a smoky flavor note.

A smoking composition according to claim 1 , wherein the where R¹, R², R³, R⁴, and R⁵ are each independently selected from the group consisting of (i) hydrogen and (ii) C1 -C5 straight or branched chain alkyl or alkoxy, wherein the alkyl or alkoxy is unsubstituted.

A smoking composition according to claim 1 , wherein the phenolic compound is guaiacol.

A smoking composition according to claim 1 , wherein the phenolic compound is selected from the group consisting of 2,6-dimethoxyphenol, 3-ethyl phenol, o-cresol, m-cresol, p- cresol, 4-isopropylphenol, and 2,3-dimethylphenol.

A smoking composition according to any one of the preceding claims, wherein a glycone moiety of the phenolic glycoside is a monosaccharide moiety, a disaccharide moiety, a trisaccharide moiety, or a derivative thereof wherein one or more protecting groups are substituted for one or more hydrogens of one or more hydroxyl groups of the monosaccharide, disaccharide, or trisaccharide moiety.

6. A smoking composition according to any one of the preceding claims, wherein the monosaccharide moiety is a glucose moiety.

7. A smoking composition according to claim 1 , wherein the phenolic glycoside is guaiacol glucoside.

8. A smoking composition according to any of the preceding claims, wherein cleavage of a glycosidic bond of the phenolic glycoside occurs at a temperature above about 140°C.

9. A smoking composition according to any of the preceding claims, wherein cleavage of a glycosidic bond of the phenolic glycoside occurs at a temperature below about 400°C.

10. A smoking composition according to any of the preceding claims, wherein cleavage of a glycosidic bond of the phenolic glycoside occurs at a temperature from about 200°C to about 300°C.

1 1 . A smoking composition according to any of the preceding claims, further comprising tobacco.

12. A smoking article comprising a composition according to any of the preceding claims.

13. A smoking article according to claim 12, comprising an aerosol forming substrate, wherein the substrate comprises the smoking composition.

14. A smoking article according to claim 13, wherein the article is configured to deliver from about 10 nanograms of the flavor compound per puff to 1 milligram of the flavor compound per puff.