Method of forming wax encapsulated flavor delivery system for tobacco

Abstract

 A method of forming a flavor delivery system for tobacco includes blending a flavor material with a molten first wax material to form a first molten blend and atomizing the first molten blend to form a plurality of core particles. Then the method includes blending the core particles with a molten second wax material to from a second molten blend and atomizing the second molten blend to form a plurality of encapsulated core particles.

Description

[0001] This disclosure relates to methods of forming flavor delivery systems for smoking articles, where the flavor material is encapsulated in wax and combined with tobacco for smoking articles.

[0002] Combustible smoking articles, such as cigarettes, typically have a tobacco substrate of shredded tobacco (usually in cut filler form) surrounded by a paper wrapper forming a tobacco rod. A cigarette is employed by a smoker by lighting one end of the cigarette and burning the tobacco rod. The smoker then receives mainstream smoke by drawing on the opposite end or mouth end of the cigarette, which typically contains a filter. These conventional cigarettes combust tobacco and generate temperatures that release volatile compounds into the mainstream smoke. To modify the flavor of the mainstream smoke, it is known to provide cigarettes with single and multi-segment mouthpiece filters that include flavorants, such as menthol.

[0003] A number of smoking articles in which an aerosol generating substrate, such as a tobacco substrate, is heated rather than combusted are known in the art. Such articles may be termed aerosol generating articles. Examples of systems using aerosol generating articles include systems that heat a tobacco containing substrate above 200 degrees centigrade to produce a nicotine containing aerosol. Typically in such heated aerosol-generating articles, an inhalable aerosol is generated by the transfer of heat from a heat source to an aerosol-forming substrate or material, which may be located within, around or downstream of the heat source. During consumption of the aerosol-generating article, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source and entrained in air drawn through the article. As the released compounds cool, they condense to form an aerosol that is inhaled by the consumer.

[0004] During the manufacture of these smoking articles the tobacco substrate is typically heated or dried to remove water, for example. During this heating or drying step volatile compounds, such as flavorants, are removed from the tobacco substrate, altering the taste of the smoking final article. Currently flavoring agents are sprayed onto the dried tobacco substrate and is termed "top loading". This procedure is difficult as dosage and final concentration of the flavor on the tobacco substrate can depend on environmental conditions and the design of the spraying unit. In addition, flavor can migrate to evolve from the tobacco substrate during storage. All of these factors can lead to unwanted product taste variability

[0005] It would be desirable to improve the smoking article taste uniformity and storage stability of flavorings added to the tobacco substrate (tobacco rod or aerosol generating substrate).

[0006] Flavor delivery systems formed according to the invention described herein can be utilized in conventional combustion smoking articles or in the aerosol generating substrate of aerosol generating smoking articles. The flavor delivery systems formed by this method can provide a predictable and stable sustained release of flavor to smoking articles. This is especially useful when combined with aerosol generating substrates that are heated during production of the aerosol generating substrate.

[0007] As described herein, a flavor delivery system for tobacco formed according to the method of the invention includes a flavor material and first wax material forming a core and a second different wax material encapsulating the core. Preferably the first wax material has a melting point of about 100 degrees centigrade or greater. The flavor material can be a hydrophobic liquid. Smoking compositions include the flavor delivery system and tobacco. Preferably the tobacco is a homogenized tobacco or cast leaf tobacco. Also described herein is a method of forming a flavor delivery system for tobacco that includes blending a flavor material with a molten first wax material to form a first molten blend and atomizing the first molten blend to form a plurality of core particles. Then the method includes blending the core particles with a molten second wax material to from a second molten blend and atomizing the second molten blend to form a plurality of encapsulated core particles.

[0008] Various aspects of the flavor delivery system formed by the method described herein may have one or more advantages relative to standard tobacco compositions. For example, the flavor delivery systems provide an enhanced flavor experience relative to tobacco compositions that do not include the flavor delivery system. The wax material does not contribute to or change the flavor notes of the tobacco composition. The wax materials encapsulate the flavor material to protect the flavor material during manufacture and storage of a smoking article that includes these tobacco compositions, while predictably releasing the flavor material during the consumption of the smoking article. Combining the flavor delivery system with tobacco to form the tobacco composition also provides a uniform distribution of flavor material throughout the tobacco composition. The flavor delivery systems can replace or enhance the tobacco flavor notes that have been modified during the production of the aerosol generating substrate. In addition, the outer wax coating or shell surrounding or encapsulating the flavor and inner wax core can be a sacrificial layer that can operate as a thermal heat sink further protecting the core from releasing the flavor material during the manufacture or storage of the tobacco composition. Additional advantages of one or more aspects of flavor delivery system described herein will be evident to those of skill in the art upon reading and understanding the present disclosure.

[0009] The term "wax material" refers to natural or synthetic wax products that are hydrophobic and can convert to a melt-liquid state (dropping point) at temperatures below 200 degrees centigrade and are virtually free of ash forming compounds.

[0010] The term "flavorant" or "flavor" refers to organoleptic compounds, compositions, or materials that alter the taste or aroma characteristics of a tobacco substrate during consumption thereof.

[0011] The term "smoking article" includes cigarettes, cigars, cigarillos and other articles in which a smokable material, such as a tobacco, 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 substrate.

[0012] As used herein, the term "smoke" or "mainstream smoke" is used to describe an aerosol produced by heating or combusting a tobacco substrate of 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 including aerosol generating articles or non-heated smoking articles.

[0013] As used herein, the term "atomizing" denotes a process whereby a liquid, which may contain molten material, a solution, an emulsion, or a combination of these, is caused to flow through one or more orifices in a sprayer, and broken into droplets or particles.

[0014] The present disclosure provides a method of forming a flavor delivery systems for smoking articles. The flavor delivery system includes a flavor material and first wax material forming a core. The first wax material encapsulates the flavor material. A second wax material surrounds the core and forms an encapsulated core or a double encapsulated flavor material. The second wax material is a different wax material than the first wax material. The flavor delivery system is preferably formed by spray chilling.

[0015] The methods and flavor delivery system described herein provide an improved way in which to incorporate flavorants into a smoking article. The types of flavorants that are used in smoking articles are typically relatively volatile and it is difficult to retain acceptable levels of the flavorants within the smoking articles during manufacture and storage. The volatile flavorants may also migrate to other parts of the smoking articles and can adversely impact the performance of other components of the smoking article, such as any sorbents provided within the filter.

[0016] The flavor delivery system formed by the method of the invention can controllably release a flavor or flavorant to its surrounding environment by increasing the temperature of the surrounding environment. The second wax material forms a shell around the core. In some embodiments the second wax material has a melting (dropping) point that is greater than the melting (dropping) point of the first wax material. In some embodiments the second wax material has a melting (dropping) point that is substantially equal to the melting (dropping) point of the first wax material. Preferably the second wax material has a melting (dropping) point that is less than the melting (dropping) point of the first wax material. The melting (dropping) point can be determined by using a standard test method for the dropping point of waxes known by ASTM D3954-94(2010).

[0017] The flavor or flavorant can be dispersed in the first wax material or encased in the first wax material. If dispersed in the wax material, this is typically known as a matrix. In encased in the wax material, this is typically known as a core-shell arrangement. Thus, the core that comprises the first wax material and flavor may be a matrix or a core-shell arrangement. Preferably the flavor or flavorant is dispersed in the first wax material. In many embodiments the flavor or flavorant is dispersed in the first wax material when the first wax material is in the molten form. The core is a particle (referred to as a core particle) that can be formed by any useful method. Preferably the core particle is formed by atomization such as spray chilling. Spray chilling provides for a more homogeneous particle size than, for instance, conventional spray drying. In addition, spray chilling reduces the amount of heat applied to the flavor thus reducing losses by evaporation or undesirable changes in the flavor material. Preferably spray chilling is performed with an inert gas such as carbon dioxide or nitrogen to further reduce conversion or undesirable changes to the flavor material.

[0018] The core particle can then be encapsulated with the second wax material to form an encapsulated core. The core particle can be dispersed in the second wax material. Preferably the core particle is dispersed in the second wax material when the second wax material is in the molten form. The encapsulated core particle can be formed by any useful method. Preferably the encapsulated core particle is formed by atomization such as spray chilling, as described above.

[0019] Useful wax materials are chosen from among the group consisting of natural or synthetic waxes and mixtures thereof. Natural waxes are derived from animals, vegetables, minerals, and petroleum. Animal derived waxes include, for example, beeswax, Chinese wax, lanolin, shellec and spermaceti wax, and the like. Vegetable derived waxes include, for example, carnuba wax, candellila wax, bayberry wax, sugar cane wax, castor wax, esparto wax, Japan wax, jojoba wax, ouricury wax, rice bran wax, soy wax, and the like. Mineral derived waxes include, for example, ceresin wax, montan wax, ozocerite wax, peat wax, and the like. Petroleum derived waxes include, for example, paraffin wax, petroleum jelly, microcrystalline wax, and the like. Synthetic waxes include, for example, polyethylene waxes, Fischer-Tropsch waxes, chemically modified waxes, substituted amide waxes, polymerized alpha-olefins, and the like.

[0020] Particularly useful wax materials do not alter the flavor of the tobacco substrate, have an appropriate melting or dropping point, flash point, fire point, polarity and are safe for consumption. The flash and fire point of the wax materials is particularly relevant when the flavor delivery system described herein is combined with tobacco and heated during the manufacturing of the tobacco substrate. It is preferred to utilize wax materials have a flash point and fire point that is greater than the temperatures applied to the wax materials during the manufacturing process. The flash point is the lowest temperature at which a flame will ignite the vapors of the heated excipient, while the fire point is the lowest temperature when the vapors ignite and burn for at least 2 seconds.

[0021] Exemplary useful waxes include polyethylene waxes, polyethylene glycol waxes, or vegetable waxes.

[0022] Illustrative polyethylene waxes are available under the trade designation CERIDUST from Clariant International Ltd., Switzerland. Illustrative polyethylene glycol waxes are available under the trade designation CARBOWAX from Dow Chemical Co., USA. Illustrative vegetable waxes are available under the trade designation REVEL from Loders Croklaan, Netherlands.

[0023] Flavorants or flavors can be liquid or solid flavors (at room temperature of about 22 degrees centigrade and one atmosphere pressure) and can include flavor formulations, flavor-containing materials and flavor precursors. The flavorant may include one or more natural flavorants, one or more synthetic flavorants, or a combination of natural and synthetic flavorants. Preferably the flavor is a liquid. Preferably the flavor is a hydrophobic liquid.

[0024] The hydrophobic liquid flavor is generally soluble in organic solvents but only weakly soluble in water. Preferably, this hydrophobic liquid flavor is characterized by a Hildebrand solubility parameter smaller than 30 MPa^1/2. The aqueous incompatibility of most oily liquids can be in fact expressed by means of Hildebrand' s solubility parameter δ which is generally below 25 MPa^1/2, while for water the same parameter is of 48 MPa^1/2, and 15-16 MPa^1/2 for alkanes. This parameter provides a useful polarity scale correlated to the cohesive energy density of molecules. For spontaneous mixing to occur, the difference in δ of the molecules to be mixed must be kept to a minimum. The Handbook of Solubility Parameters (ed. A.F.M. Barton, CRC Press, Bocca Raton, 1991) gives a list of δ values for many chemicals as well as recommended group contribution methods allowing to calculate δ values for complex chemical structures.

[0025] Flavorants or flavors refer to a variety of flavor materials of natural or synthetic origin. They include single compounds and mixtures. Preferably the flavor or flavorant has flavor properties that enhance the experience of a non-combustible smoking article to, for example, provide an experience similar to that resulting from smoking a combustible smoking article. For example, the flavor or flavorant can enhance flavor properties such as mouth fullness and complexity. Complexity is generally known as the overall balance of the flavor being richer without dominating single sensory attributes. Mouth fullness is described as perception of richness and volume in the mouth and throat of the consumer.

[0026] Suitable flavors and aromas include, but are not limited to, any natural or synthetic flavor or aroma, such as tobacco, smoke, menthol, mint (such as peppermint and spearmint), chocolate, licorice, citrus and other fruit flavors, gamma octalactone, vanillin, ethyl vanillin, breath freshener flavors, spice flavors such as cinnamon, methyl salicylate, linalool, bergamot oil, geranium oil, lemon oil, and ginger oil, and the like.

[0027] Other suitable flavors and aromas may include flavor compounds selected from the group consisting of an acid, an alcohol, an ester, an aldehyde, a ketone, a pyrazine, combinations or blends thereof and the like. Suitable flavor compounds may be selected, for example, from the group consisting of phenylacetic acid, solanone, megastigmatrienone, 2-heptanone, benzylalcohol, cis-3-hexenyl acetate, valeric acid, valeric aldehyde, ester, terpene, sesquiterpene, nootkatone, maltol, damascenone, pyrazine, lactone, anethole, iso-s valeric acid, combinations thereof, and the like.

[0028] Further specific examples of flavors may be found in the current literature, for example, in Perfume and Flavor Chemicals, 1969, by S. Arctander, Montclair N.J. (USA); Fenaroli's Handbook of Flavor Ingredients, CRC Press or Synthetic Food Adjuncts by M.B. Jacobs, van Nostrand Co., Inc.. They are well-known to the person skilled in the art of flavoring, i.e. of imparting an odor or taste to a product.

[0029] In some embodiments, the flavorant is a high potency flavorant, and is typically used at levels that would result in less than 200 parts per million in the aerosol or mainstream smoke. Examples of such flavorants are key tobacco aroma compounds such as beta-damascenone, 2-ethyl-3,5-dimethylpyrazine, phenylacetaldehyde, guaiacol, and furaneol. Other flavorants can only be sensed by humans at higher concentration levels. These flavorants, which are referred to herein as the low potency flavorants, are typically used at levels that results in orders of magnitude higher amounts of flavorant released into the aerosol or mainstream smoke. Suitable low potency flavorants include, but are not limited to, natural or synthetic menthol, peppermint, spearmint, coffee, tea, spices (such as cinnamon, clove and ginger), cocoa, vanilla, fruit flavors, chocolate, eucalyptus, geranium, eugenol and linalool.

[0030] In preferred embodiments the flavor delivery system first wax material has a melting point of about 100 degrees centigrade or greater, or about 120 degrees centigrade or greater, or about 140 degrees centigrade or greater, or about 150 degrees centigrade or greater. In many embodiments the first wax material has a melting point in a range from about 100 degrees centigrade to 150 degrees centigrade or from about 110 degrees centigrade to about 140 degrees centigrade. In many embodiments the first wax material has a melting point up to about 200 degrees centigrade.

[0031] In preferred embodiments the flavor delivery system second wax material has a melting point of about 100 degrees centigrade or less, or about 90 degrees centigrade or less, or about 80 degrees centigrade or less, or about 70 degrees centigrade or less. In many embodiments the second wax material has a melting point in a range from about 50 degrees centigrade to 100 degrees centigrade, or from about 50 degrees centigrade to about 80 degrees centigrade. In many embodiments the second wax material has a melting point down to about 40 degrees centigrade.

[0032] In preferred embodiments the first wax material has a higher melting point than the second wax material. In some embodiments the first wax material has a higher melting point that is about 30 degrees, or at least 40 degrees or at least 50 degrees higher than the second wax material. Flavor is released from the flavor delivery system as the first wax material is heated above its melting point.

[0033] The flavor material can be present in the first wax material in any useful amount. In many embodiments the flavor is present in the core in at least about 5 wt%. In many embodiments the flavor is present in the core in at less than about 50 wt%. In many embodiments the flavor is present in the core in a range from about 5 to about 50 wt%, or from about 5 to about 35 wt%, or from about 10 to about 30 wt%.

[0034] The use of the flavor delivery system formed by the method described herein to provide a flavorant within a smoking article advantageously reduces the loss of the flavorant during storage so that a larger proportion of the flavorant is retained within the smoking article. The flavor delivery system can therefore provide a more intense flavor to the mainstream smoke. Since the loss of the flavorant is reduced, it is possible to incorporate a smaller amount of the flavorant into each smoking article whilst providing the same effect on the flavor as provided in current smoking articles.

[0035] The core can have any useful particle size or largest lateral dimension. In many embodiments the core has a particle size of less than about 30 micrometres or less than about 20 micrometres. In many embodiments the core has a particle size greater than about 1 micrometre or greater than about 5 micrometres. In many embodiments the core has a particle size in a range from about 1 to about 30 micrometres, or from about 5 to about 25 micrometres, or from about 5 to about 20 micrometres.

[0036] The encapsulated core can have any useful particle size or largest lateral dimension. In many embodiments the encapsulated core has a particle size of less than about 250 micrometres or less than about 200 micrometres. In many embodiments the encapsulated core has a particle size greater than about 25 micrometres or greater than about 50 micrometres. In many embodiments the encapsulated core has a particle size in a range from about 25 to about 300 micrometres, or from about 25 to about 250 micrometres, or from about 50 to about 200 micrometres.

[0037] The core can be combined with the first wax material in any useful amount to from the encapsulated core or flavor delivery system. In many embodiments the core represents at least about 1 wt% of the encapsulated core particle total weight. In many embodiments the core represents at least about 5 wt% of the encapsulated core particle total weight. In many embodiments the core represents less than about 50 wt% of the encapsulated core particle total weight. In many embodiments the core is represents a range from about 1 to about 50 wt% of the encapsulated core particle total weight, or from about 5 to about 50 wt% of the encapsulated core particle total weight, or from about 10 to about 35 wt% of the encapsulated core particle total weight.

[0038] The flavor delivery system can be combined with tobacco to form a tobacco composition or smoking composition that provides a stable and predictable flavor release as the tobacco composition or smoking composition is heated to temperature to melt the wax material and release the flavor into the mainstream smoke or aerosol for consumption. The flavor delivery system can be combined with cut tobacco to form a tobacco composition or smoking composition for use with conventional combustion smoking articles. Preferably the flavor delivery system can be combined with reconstituted or homogenized tobacco to form a tobacco composition or smoking composition for use with aerosol generating articles. Preferably the homogenized tobacco is a cast leaf tobacco.

[0039] Smoking articles that include aerosol generating devices typically comprise an aerosol forming 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-forming substrate.

[0040] "Aerosol forming 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 forming substrate can release a flavor compound upon combustion or heating. The substrate can comprise both liquid and solid components. The aerosol forming substrate may comprise tobacco and flavor delivery system wherein the flavor is released from the substrate upon heating. The aerosol forming substrate may further comprise an aerosol former. Examples of suitable aerosol formers are glycerine and propylene glycol. Optionally, the aerosol forming 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 forming substrate may be deposited on the surface of the carrier in the form of, for example, a sheet, foam, gel or slurry. The aerosol-forming 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.

[0041] Homogenized tobacco can be used to make an 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 (cast leaf) 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.

[0042] The flavor delivery system can be incorporated into the cast leaf tobacco substrate formed by a cast leaf process. 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. Cast leaf tobacco substrates can be formed by combining homogenized tobacco powder with water, glycerine, and other optional additives to form a slurry and combining the flavor delivery system in the slurry. The slurry is then cast into a form and dried (heated) to remove water and form the cast leaf tobacco substrate.

[0043] A cast leaf process may involve applying temperatures of up to about 140°C, such as between about 90°C and 140°C. Accordingly, the one or both of the wax materials of the flavor delivery system is preferably stable at such temperatures. Preferably the first wax material of the core is stable at these temperatures so that the flavor is not released during the drying step of the cast leaf process. In many embodiments the second wax material has a melting point that is substantially the same as the drying temperature of the drying step of the cast leaf process. In some embodiments the second wax material has a melting point that is less than the drying temperature of the drying step of the cast leaf process. In these embodiments at least a portion of the shell or second wax material melts away from of melts off the core and is dispersed within the homogenized tobacco material. Preferably the first wax material forming the flavor core has a melting point that is greater than the temperature used to form the cast leaf tobacco substrate.

[0044] 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.

[0045] As used herein, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise.

[0046] As used herein, "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. The term "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

[0047] 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.

[0048] The words "preferred" and "preferably" refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure, including the claims.

FIG. 1 is a schematic process flow diagram of an illustrative process 100 for forming the flavor core particle 11.

Fig. 2 is a schematic diagram of an illustrative flavor core particle 11 formed by the process of FIG. 1.

FIG. 3 is a graph of cumulative particle size % of the flavor core particle 11.

FIG. 4 is a schematic process flow diagram of an illustrative process 200 for forming the encapsulated flavor core particle 10.

FIG. 5 is a schematic diagram of an illustrative flavor delivery system 10 or encapsulated flavor core.

[0049] The schematic drawings are not necessarily to scale and are presented for purposes of illustration and not limitation. The drawings depict one or more aspects described in this disclosure. However, it will be understood that other aspects not depicted in the drawing fall within the scope and spirit of this disclosure.

[0050] FIG. 1 illustrates a process for forming the flavor core particle 11. A flavor or flavorant 110 is blended with a first molten wax material 120 at the mixing block 140. The flavor or flavorant 110 is homogeneously mixed with the first molten wax material 120 with a static mixer 145 to form a first molten blend. This first molten blend enters the atomization nozzle 150 at a molten blend inlet 152. An atomizing gas 130 enters the atomization nozzle 150 at a gas inlet 154. Preferably the molten blend inlet 152 and the gas inlet 154 are separate inputs into the atomization nozzle 150. The first molten blend and the gas 130 travel through the atomization nozzle 150 and a plurality of flavor core particles 11 are formed in a spray chamber 160. The flavor core particles 11 are formed by cooling below the melting point of the first wax material 120 and entraining the flavor 110 material within the first wax material 120. This process is referred to as "spray chilling". The atomizing gas 130 is preferably an inert gas such as nitrogen or carbon dioxide for example.

[0051] The spray chilling process described herein has a number of advantages for encapsulating flavor or flavourants for tobacco. Flavors for tobacco are typically volatile and can be stripped away by the atomization gas of typical spray chilling processes. In contrast, the disclosed spray chilling process utilizes a nozzle that separates the atomization gas from the molten blend until they exit the nozzle. Thus the residence time of the atomization gas with the molten blend is reduced as compared to other spray chilling processes. In addition the volatile flavor material or flavor core particle is combined with the molten wax just prior to entering the atomization nozzle. Thus the residence time of the molten wax and the volatile flavorant or flavor core is reduced as compared to prior flavor encapsulating processes. Additional advantages of one or more aspects of spray chilling process described herein will be evident to those of skill in the art upon reading and understanding the present disclosure.

[0052] The result of this process 100 is a free flowing powder consisting of spherical shaped particles 11 which contain the used flavor ingredient(s). The powder or flavor core particles 11 can optionally be washed with ethanol or other solvent to remove the superficially adsorbed flavor ingredient(s). The powder or flavor core particles 11 can then be sieved to remove big particles (>250µm) and to generate two sub fractions of the encapsulated flavor core particles (60-125µm & 125-250 µm), as desired.

[0053] FIG. 2 illustrates a flavor core particle 11 that includes a flavor material 12 and first wax material 14 forming a core 11. The core 11 has a particle size or largest lateral dimension D₁. FIG. 3 is a graph of cumulative particle size % of the flavor core particle 11. FIG. 3 shows the particle size distribution of the flavor core particles 11 according to Example 1 below. The particle size of the particles 11 can be analyzed by laser diffraction method. The result was a d50 of 6µm and a d90 of 19µm which means that 50% of the particles are smaller than 6µm and 90% are smaller than 19µm.

[0054] FIG. 4 is a schematic process flow diagram of an illustrative process 200 for forming the encapsulated flavor core particle 10. The flavor core particles 11 are blended with a second molten wax material 130 at the mixing block 140. The flavor core particles 11 are homogeneously mixed with the second molten wax material 130 with a static mixer 145 to form a second molten blend. This second molten blend enters the atomization nozzle 150 at a molten blend inlet 152. An atomizing gas 130 enters the atomization nozzle 150 at a gas inlet 154. Preferably the molten blend inlet 152 and the gas inlet 154 are separate inputs into the atomization nozzle 150. The second molten blend and the gas 130 travel through the atomization nozzle 150 and a plurality of encapsulated flavor core particles 10 are formed in a spray chamber 160. The encapsulated flavor core particles 10 are formed by cooling below the melting point of the second wax material 120. This process is referred to as "spray chilling". The atomizing gas 130 is preferably an inert gas such as nitrogen or carbon dioxide for example.

[0055] Referring now to FIG. 5, the encapsulated flavor core particles 10 or flavor delivery system 10 includes a flavor material 12 and first wax material 14 forming a core 11 and a second wax material 16 encapsulating the core 11. The second wax material 16 is a different wax material than the first wax material 14.

[0056] The core 11 has a particle size or largest lateral dimension D₁. The flavor delivery system 10 has a particle size or largest lateral dimension D₂.

[0057] Non-limiting examples illustrating flavor delivery system as described above and tobacco substrates and smoking articles having such flavor delivery systems are described below.

Examples

[0058] A variety of wax materials were evaluated as described below for suitability in the flavor delivery system as described above.

[0059] Flash and fire points for selected wax excipients were determined according ISO 2592 (Cleveland open cup method). The flash point is the lowest temperature at which a flame will ignite the vapors of the heated excipient, while the fire point is the lowest temperature when the vapors ignite and burn for at least 2 seconds. Results of this testing is reported in Table 1.

Table 1

Excipient	Fire point (°C)	Flash point (°C)
Rice bran (Kahlwax 2811)	299	333
Sunflower wax (Kahlwax 6607)	305	335
Carnauba wax (Kahlwax 2442L)	315	345
Candelilla wax (Kahlwax 2039)	269	299
Cutina wax	325	341
Licowax 521 PED	249	>309
Ceridust 2051	297	329
Ceridust 3610	263	>303
Deurex MX 9820	277	329
Deurex ME 1620	261	>321
Deurex MT 9120	295	339
Sasolwax H1	287	327
Sasolwax H105	na	Na
Vestowax EH100	267	295
Vestowax SH105	310	333
PEG 6000	233	>259
PEG 35000	259	>319
Ceridust 6050M	271	319
Revel A	319	347

[0060] A sensory analysis of wax materials is determined using the descriptive criterion "overall sensory neutrality" to indicate intensity differences. As sensory and psychological fatigue sets in after 7-8 samples, a balanced incomplete block design (BiB) (ISO 29842) is selected for the ranking test (ISO 8587). Assessors receive per session five samples in random order and are asked to rank the samples according to the criterion. Four sessions are performed in order to achieve an adequate level of precision. Results of this BiB ranking are reported in Table 2.

[0061] A number of flavor delivery system are formed by first spray chilling a flavor with first wax material to form a core and then spray chilling the core with a second wax to form the encapsulated core or flavor delivery system. Table 3 reports the results of the materials screened.

Table 3

Example no.	Core	shell	flavor load	sieve fraction
1	ceridust 3610 (polyethylene wax)	Revel A	25%	63-125µm
2	ceridust 3610 (polyethylene wax)	Revel A	25%	125-250µm
3	ceridust 3610 (polyethylene wax)	Revel A	35%	63-125µm
4	ceridust 3610 (polyethylene wax)	Revel A	35%	125-250µm
5	ceridust 3610 (polyethylene wax)	Sunflower wax	25%	63-125µm
6	ceridust 3610 (polyethylene wax)	Sunflower wax	25%	125-250µm

[0062] Examples 1 and 2 and a Core utilized in Examples 1 and 2 are formed utilizing the spray chilling process parameters described in the Table 4 below. Examples 1 and 2 had the following construction: Core material: Ceridust 3610; Mass fraction of flavor in core: 25%; Shell material: Revel A; Amount of core material suspended in shell material: 10%.

Table 4

Example	Shell/Core Construction	Kg CO2/Kg wax	Ppre bar	Tpre °C	Tpost °C
Core	C3610 (25% fl)	4.7	79	146	56
1	Revel A/C3610 (63-125 µm)	2.5	73	94	29
2	Revel A/C3610 (125-250 µm)	3.0	75	93	27

[0063] Examples 5 and 6 and a Core utilized in Examples 1 and 2 are formed utilizing the spray chilling process parameters described in the Table 5 below. Examples 5 and 6 had the following construction: Core material: Ceridust 3610; Mass fraction of flavor in core: 25%; Shell material: Sunflower wax; Amount of core material suspended in shell material: 10%.

Table 5

Example	Shell/Core Construction	Kg CO2/Kg wax	Ppre bar	Tpre °C	Tpost °C
Core	C3610 (25% fl)	4.1	79	150	38
5	Sun/C3610 (63-125 µm)	3.1	77	94	36
6	Sun/C3610 (125-250 µm)	4.7	77	92	35

[0064] The examples 1-6 are then analyzed for particle size distribution, bulk density and morphology.

[0065] The particle size distribution is measured by laser diffraction method with the Malvern Mastersizer 2000. The liquid dispersion unit "Hydro MU" is used to measure the particles dispersed in ethanol. After the samples are dispersed in ethanol the ultrasonic bath is turned on for a period of 3 minutes to break the agglomerates. After 1 minute the measurement is initiated. All samples are measured twice and the average values are reported. The interpretation of the data is done according to the theory of Fraunhofer.

[0066] The Mastersizer breaks the agglomerates by using an ultrasonic batch prior to the particle size measurement; the particle size measured by laser diffraction method differs from the expected particle size of the sieved fractions. By sieving the samples, the agglomerates are not destroyed and the sieved fractions in fact consist of agglomerates rather than fractions of single particles.

[0067] Figure 6 reports the particle size distributions of the core-shell samples of Examples 1-6 produced by the double spray chilling process described above. The bulk density of the core-shell samples of Examples 1-6 is measured in accordance to DIN ISO 697. In Figure 7 the bulk densities is reported.

[0068] Figures 8-10 show scanning electron microscope (SEM) pictures of Example 1 (Revel A + 10% C3610 -25% fl.- 63-125µm). Figure 8 gives an overview picture of the particles in Example 1. Nearly all particles are spherical. In Figure 9 a close up of an agglomerate is shown. The big particles indicate double encapsulated particles and the small particles indicate a single layer of encapsulate. Figure 10 shows a close up of a single particle with a particle size of about 80 µm. The surface is very smooth and without any capillaries or holes.

[0069] The flavor release of the flavor delivery system described herein was then evaluated. A flavor delivery system described herein that was formed by a two stage spray chilling was added to a cast leaf slurry prior to caste leaf tobacco substrate generation at a level of 3% (w/w). The cast leaf was generated according to a standard cast-leaf procedure involving a drying step at approximately 100°C. No special observations were made during cast leaf manufacturing, indicating no to low flavor losses. Using the generated cast leaf, consumables (tobacco sticks) were manufactured to be used in the aerosol generating substrate.

[0070] Flavor release analyses were performed by the Health Canada Intense smoking regime. The following two examples illustrate the successful release of flavoring ingredients by the described flavor delivery system. For both examples the quantified flavoring ingredients are not detectable in the aerosol of the consumable without addition of the flavor delivery system described herein.

[0071] The release quantification of the flavoring agent 3-ethylphenol using a combination of Revel A/ceridust (35%) with a particle size of 63-125 µm (see Example 3) in the cast leaf of the consumable was about 14 ng per 12 puffs Health Canada intense regime.

[0072] The release quantification of the flavoring agent pyrazine using a combination of sunflower/ceridust (25%) with a particle size of 63-125 µm (see Example 5) in the cast leaf of the consumable was about 18 ng per 12 puffs Health Canada intense regime.

Claims

1. A method of forming a flavor delivery system for tobacco comprising:

blending a flavor material with a molten first wax material to form a first molten blend: atomizing the first molten blend to form a plurality of core particles;

blending the core particles with a molten second wax material to form a second molten blend; and

atomizing the second molten blend to form a plurality of encapsulated core particles.

2. A method according to claim 1, wherein the step of atomizing the first molten blend comprises cooling the plurality of core particles and the step of atomizing the second molten blend comprises cooling the encapsulated core particles.

3. A method according to claim 1 or 2, wherein the step of atomizing the first molten blend and the step of atomizing the second molten blend comprises spray chilling.

4. A method according to any one of claims 1 to 3, wherein the step of atomizing the first molten blend and the step of atomizing the second molten blend utilizes an inert gas.

5. A method according to any of the preceding claims, wherein the material is a hydrophobic liquid.

6. A method according to any of the preceding claims, wherein the core particle has a particle size in a range from about 1 micrometre to about 25 micrometres.

7. A method according to any of the preceding claims, wherein the encapsulated core particle has a particle size in a range from about 25 micrometres to about 250 micrometres.

8. A method according to any of the preceding claims, further comprising combining the encapsulated core particles with a tobacco material.

9. A method according to any of the preceding claims, wherein the first wax material has a greater melting point than the second wax material.

10. A method according to any of the preceding claims, wherein the first wax material has a melting point of about 100 degrees centigrade or greater.

11. A method according to any of the preceding claims, wherein the step of atomizing the first molten blend comprises flowing the first molten blend and an atomization gas through an atomization nozzle.

12. A method according to any of the preceding claims, wherein the step of atomizing the second molten blend comprises flowing the second molten blend and an atomization gas through an atomization nozzle.

13. A method according to claims 11 or 12, wherein the atomization nozzle comprises an atomization gas inlet and a separate molten blend inlet.

14. A method according to any one of claims 11 to 13, wherein the atomization gas and the first or second molten blend combine at an exit of the atomization nozzle.

15. A method according to any of the preceding claims, further comprising washing the core particles with a solvent prior to forming the second molten blend.

Drawing