WO2020002589A1

WO2020002589A1 - A method for manufacturing reconstituted plant material

Info

Publication number: WO2020002589A1
Application number: PCT/EP2019/067311
Authority: WO
Inventors: Kate FERRIE; Edward Ross SHENTON
Original assignee: Nerudia Limited
Priority date: 2018-06-29
Filing date: 2019-06-28
Publication date: 2020-01-02
Also published as: GB201810728D0

Abstract

A method for manufacturing a reconstituted plant material includes the steps of extracting a fibrous plant material with a liquid solvent to provide a first extract and a fibrous portion, separating the first extract from the fibrous portion, extracting the first extract with supercritical carbon dioxide to provide a second extract, forming a base sheet from the fibrous portion, and applying the second extract to the base sheet.

Description

A Method for Manufacturing Reconstituted Plant Material

Field of the Invention

The present invention relates to a method for reconstituting a plant material by a paper-making process, and a reconstituted tobacco product.

Background

During the manufacturing process for tobacco products, such as cigarettes, tobacco waste is produced. The tobacco waste is typically in the form of tobacco dust, leaf or stem. The tobacco waste can be collected and processed to provide what is known as reconstituted tobacco, or“recon”.

Two distinct methods are most commonly employed to manufacture reconstituted tobacco, these are i) a paper-making process, and ii) slurry casting. The products that result from these distinct processes have notably different properties and characteristics. In particular, recon formed by the paper-making process typically has a reduced aroma/flavour and nicotine content in comparison to that formed by slurry casting.

In slurry casting the tobacco waste is milled to a fine powder and mixed with an aqueous solvent, typically water. The resultant slurry may undergo further milling to reduce the particle size of the tobacco material further. The slurry is then cast on a surface and dried to form a sheet. The dried sheet may be shredded to be used within various tobacco products, for example as a cigarette filler.

In the paper-making process the tobacco waste is mechanically beaten in the presence of an aqueous solvent to digest and process the tobacco into workable fibres to be made into a paper or web. Subsequently, water soluble compounds present in the tobacco are extracted into the aqueous solvent. The aqueous extract and insoluble fibrous portion are separated. The separated fibrous portion, which may also be described as a“pulp”, undergoes further processing to form a base sheet via a typical paper-making procedure. The aqueous extract is concentrated and then reapplied to the base sheet. The base sheet is then dried to form a paper.

The paper formed by the above process can be shredded and used as a filler within typical smoking articles such as cigarettes. Alternatively, it may be used as a wrapper to contain a tobacco rod. Conventional reconstituted tobacco paper of this kind is generally not suitable for“heat-not-burn” (“HNB”) devices. For recon paper to be suitable for use within a HNB device a humectant must also be incorporated. Typical humectants include propylene glycol (“PG”) or vegetable glycerine (“VG”).

An HNB device heats the tobacco without burning it, i.e. it does not undergo combustion. The purpose of HNB devices is to avoid production, and subsequent inhalation, of harmful combustion products such as tar. By heating a humectant-impregnated recon paper the humectant is vaporised to form an aerosol, also referred to as a“vapour”. The aerosol may contain aroma/flavour compounds and/or nicotine derived from the recon paper. It is the aerosol which enables the user to simulate the act of smoking. WO 2017/051034 describes a reconstituted tobacco made by a paper making process which is suitable for an HNB device. In which, a humectant is added to the concentrated tobacco extract before application to the base-sheet to provide a humectant- impregnated recon paper.

Associated with the recon paper-making process is the loss of volatile compounds, such as nicotine and flavour compounds, from the tobacco during processing. This is linked with the large volumes of water used to digest and process the tobacco, and the high temperatures used to evaporate the water.

It is desirable to provide a safe and efficient way of increasing the nicotine and/or flavour content of recon tobacco made by a paper-making process. In particular it is desirable to provide a product that delivers an enhanced sensory experience to the consumer, which is consistent over multiple consumables.

Various efforts have been made to improve the nicotine content of recon tobacco made by a papermaking process. In US 3422819, the nicotine content of a cigarette wrapper was increased by applying a solution of nicotine salt to a reconstituted tobacco sheet after manufacture of the paper. Alternatively, it is recognised in US 3422819 that“the solution of nicotine salt may be added to the stock from which paper is formed”. The term“stock” refers to the mixture of pulp, fillers, other papermaking materials and water (see C. Biermann, Handbook of Pulping and Papermaking, 2^nd Edition). The stock, therefore, is the fibrous mixture post-extraction that enters the paper-making machine to be formed into a base sheet.

US 3,861 ,400 describes a method of increasing the nicotine content of recon tobacco formed by a slurry casting method. This is achieved by the addition of specific polyuronic acid nicotine salt derivatives to a tobacco-water slurry. The products produced by slurry casting, and the method itself, are distinct to that of the recon paper-making process.

GB 1466912 describes an alternative method of increasing the nicotine content within recon tobacco paper. In which, roots of plants of the genus Nicotiana are grown in a specific culture medium. The grown roots are combined with tobacco solids to form a reconstituted tobacco base sheet. The spent culture medium, which includes nicotine exuded by the roots, is added to the tobacco soluble obtained in the production of the reconstituted tobacco. The tobacco soluble is concentrated and added to the base sheet. CN 103468403 and CN 103462204 describe a method for extracting tobacco aroma compounds by conducting two separate extraction processes directly upon the tobacco raw material. This includes separate water extraction and supercritical carbon dioxide (scCC ) extraction on the tobacco raw material. The two extracts are then combined and applied to the reconstituted tobacco.

Alternatively, CN 103783660 describes SCCO2 extraction on tobacco leaf fragments to extract flavour compounds. The flavour compounds are then separated, purified and reapplied to a reconstituted tobacco product by spraying or coating.

In the context of reconstituted tobacco suitable for use within a HNB device a number of documents describe that flavour additives may be optionally added to the humectant-impregnated recon paper, see for example, WO2017/051034, US 5325877, US 5715844 and US 2006/0021626. However, it is not specified within these documents how the flavour additives are added, nor at what stage in the paper-making process the flavour additives are added. Indeed, it is not recognised that flavour compounds are lost during the recon paper-making process. Therefore, it is apparent that the flavour additives are not intended to replace lost flavour during processing, but instead to impart a different taste experience to that of tobacco.

The present invention has been devised in light of the above considerations.

Summary of the Invention

According to a first aspect of the invention, there is provided a method for manufacturing a reconstituted plant material, the method comprising: extracting a fibrous plant material with a liquid solvent to provide a first extract and a fibrous portion; separating the first extract from the fibrous portion;

extracting the first extract with supercritical carbon dioxide to provide a second extract;

forming a base sheet from the fibrous portion;

applying the second extract to the base sheet.

Advantageously, by carrying out supercritical extraction on the first extract flavour compounds are recovered and retained. This prevents loss of flavour compounds by evaporation or decomposition during processing of the first extract. Furthermore, supercritical extraction on a liquid feedstock may provide a continuous process that can be automated, which may provide lower operating costs. Such continuous processes are more difficult to achieve when the feedstock is solid (e.g. tobacco raw material). Also, by carrying out supercritical extraction on the first extract, rather than directly upon the fibrous plant material itself, the supercritical extraction of unwanted compounds is avoided.

Example unwanted compounds include those that are insoluble in the liquid solvent (i.e. not extracted into the liquid solvent), thus their removal by a direct supercritical CO2 extraction of the plant material would be unnecessary. During liquid extraction the mixture of fibrous plant material and solvent are mechanically beaten to form a pulp. A pulp consists of lignocellulosic materials, e.g. plant fibres, which have been broken down physically and/or chemically such that discrete fibres are liberated and can be dispersed in solvent and reformed to form a web. Optionally, additional chemicals may be added to the mixture to aid digestion of the tobacco material and pulp formation. Suitable chemicals are known to those skilled in the art.

Preferably the method further comprises the steps of concentrating the first extract to provide a concentrated extract, and combining the second extract with the concentrated extract before applying the second extract to the base sheet.

Advantageously, by combining the second extract to the concentrated extract (which also contains other soluble compounds such as nicotine derived from the plant material) a homogeneous mixture of nicotine and flavour compounds is obtained. Consequently, a greater degree of intermingling of nicotine and flavour compounds is achieved in the recon paper to provide an improved sensory experience to the user. A further advantage is improved impregnation and uniform distribution of flavouring throughout the final product.

The critical point of carbon dioxide has a critical temperature of 31 °C and critical pressure of 74 bar. The conditions for supercritical extraction are easily tuned by adjusting temperature and pressure. Consequently, a wide range of different flavour compounds can be extracted. Furthermore, the conditions may be tuned to selectively extract certain compounds. This allows the flavour of the final product to be tailored as desired.

Suitable liquid solvents are known to those skilled in the art. These include non-aqueous solvents and aqueous solvents. Examples of non-aqueous solvents includes but is not limited to alcohols, such as ethanol and propanol; acetone; acetonitrile; benzene; dichloromethane; ethyl acetate;

hexane; and toluene.

Preferably, the liquid solvent is an aqueous solvent. More preferably, the liquid solvent is water. Optionally, the aqueous solvent may contain a co-solvent. Preferably, the co-solvent is water miscible. Examples of co-solvents are alcohols, acetone and acetonitrile.

The temperature of the tobacco-water mixture during liquid extraction is generally within the range 10 - 100 °C. Preferably, the temperature is within the range 30 - 90 °C. Particularly, preferred is the range 30 - 70 °C.

The liquid extraction time generally ranges from 30 minutes to 6 hours. Preferably, the liquid extraction time is less than 4 hours, such as less than 3 hours, or such as less than 2 hours.

Particularly, preferred is a liquid extraction time less than 1 hour. Preferably, the fibrous plant material is tobacco.

Advantageously, as the invention is primarily intended to provide a smoking consumable, the use of tobacco provides a reconstituted plant material product having the inherent properties of tobacco, for example the texture, aroma and nicotine content.

Preferably, the tobacco is in the form of tobacco leaf, tobacco stem, tobacco powder and/or tobacco dust.

Advantageously, these forms of tobacco are typically derived as waste from tobacco processing, thus by utilising this“waste” to form the product of the invention the amount of unused tobacco material is minimised.

Preferably, the supercritical carbon dioxide extraction pressure is within the range 74 to 350 bar, such as 74 to 200 bar.

Advantageously, these pressures provide sufficient extraction of the compounds of interest whilst providing a process with good economic efficiency

Preferably, the supercritical carbon dioxide extraction temperature is within the range 31 °C to 100 °C, such as 40 °C to 80 °C and 40 °C to 60 °C

Advantageously, these temperatures provide sufficient extraction of the compounds of interest whilst providing a process with good economic efficiency. Additionally, the use of extraction temperatures lower than 100 °C improves the economic efficiency by providing milder reaction conditions.

Preferably, the supercritical carbon dioxide contains 1 to 20 mol % of an entrainer. An entrainer is used to modify the solvation characteristics of supercritical carbon dioxide. Examples of entrainers include alcohols, such as methanol and ethanol.

Advantageously, the presence of an entrainer in this amount enhances the solvent power of the supercritical carbon dioxide towards the compounds of interest.

The supercritical extraction may be carried out in a countercurrent column or cocurrent column. Preferably, the supercritical extraction is countercurrent supercritical carbon dioxide extraction. Advantageously, the use of countercurrent extraction improves extraction of compounds into the supercritical carbon dioxide. Also, countercurrent extraction reduces the amount of supercritical carbon dioxide required for extraction.

The method according to the first aspect of the invention may further comprise a step of making an HNB consumable.

According to a second aspect of the invention there is provided a reconstituted tobacco product produced by a process according to the first aspect of invention.

According to a third aspect of the invention, there is provided use of the reconstituted tobacco product according to the second aspect of the invention in a HNB device.

According to a fourth aspect of the invention, there is provided an HNB consumable comprising the reconstituted tobacco product according to the second aspect of the invention.

According to a fifth aspect of the invention, there is provided an HNB system comprising an HNB consumable according to the fourth aspect of the invention, and an HNB device.

Brief Description of the Drawings

A complete understanding of preferred embodiments of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent, detailed description, provided by way of example only and in which:

Figure 1 is an illustrative view of a manufacturing process for producing reconstituted tobacco for use in accordance with the present invention

Detailed Description of the Invention

Before the invention is described in further detail, it is to be understood that the invention is not limited to the particular embodiments described, and as such may, of course, vary. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and not intended to be limiting, since the scope of the present invention will be limited by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs or as determined by the context in which such terms are used. Although any methods and materials similar or equivalent to those described herein can also be used in the practise or testing of the present invention, a limited number of exemplary methods and materials are described herein. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and materials in connection with which the publications are cited. The publications discussed herein are provided solely for their disclosure prior to the filing date of the present patent application.

The present invention provides a method for manufacturing reconstituted plant material comprising the following steps: extracting a fibrous plant material with a liquid solvent to provide a first extract and a fibrous portion; separating the first extract from the fibrous portion;

forming a base sheet from the fibrous portion;

applying the second extract to the base sheet.

Figure 1 illustrates the preferred embodiment of the invention, wherein the fibrous plant material is tobacco. With reference to Figure 1 this embodiment is described in detail below.

Any suitable plant material that requires reconstituting as a paper, wherein the loss of volatile compounds during processing (such as alkaloid derivatives or flavour compounds) is detrimental to the final product, may be used in the present invention.

Preferably, the plant material is tobacco. Any type of tobacco may be used in the present invention. This includes, but is not limited to, flue-cured tobacco, burley tobacco, Maryland Tobacco, dark-air cured tobacco, oriental tobacco, dark-fired tobacco, perique tobacco and rustica tobacco. This also includes blends of the above mentioned tobaccos.

Any suitable parts of the tobacco plant may be used. This includes leaves, stems, roots, bark, seeds and flowers. In particular, tobacco waste is used, tobacco waste is typically in the form of tobacco leaf, stem, powder or dust.

Initially, the tobacco material is added to an aqueous solvent to extract the water soluble tobacco components 1. Prior to this the tobacco material may be optionally grinded, threshed or cut.

Typically, the amount of aqueous solvent to tobacco material is within the range 75 - 99 wt % of the total weight of the tobacco-aqueous solvent mixture.

The tobacco-aqueous solvent mixture is mechanically beaten during extraction 1 in order to create a pulp. After extraction 1 , the fibrous portion and aqueous extract are separated, step 2. This may be achieved by centrifugation, filtration, mechanical pressing or any other methods known in the papermaking industry.

The separated fibrous portion 9 is further refined to form a refined pulp suitable for entry into the paper-making machine 10. Typical pulp refiners include disk refiners and conical refiners. The refined pulp is then properly slurried and treated to remove contaminants and entrained air.

The refined pulp slurry is applied to a paper-making machine 11. The paper-making machine comprises a forming section 11 , drainage section, pressing section 12 and a drying section 14. In the forming section 11 the slurry of refined pulp 10 is applied to a wire sheet, also known as a“forming fabric”, to form a web. The wire permits draining of excess water from the web by gravity to form a sheet. Alternatively, suction equipment may also be used permit drainage. Excess water is further removed by means of a press 12. The press is a typically a pair of squeeze or wringer rolls designed to remove water mechanically and smooth and compress the sheet formed. Drying 11 of the sheet is typically facilitated by drum dryers.

The aqueous extract 3 is subjected to extraction with supercritical carbon dioxide 4.

The supercritical CO2 extraction 4 may be carried out in typical high-pressure vessels known in the art.

Following extraction the supercritical CO2 and solubilised components are transferred to a separator 4. In the separator, the solvation power of the supercritical fluid is decreased by adjusting the temperature and/or pressure. Generally, an increase in temperature may be used to decrease solvation. Generally, a decrease in pressure may be used to decrease solvation. It is preferred that a decrease in pressure is used to decrease solvation and provide separation of the second extract.

After the CO2 has been decompressed it may be compressed and returned back to the extraction stage.

The aqueous extract 5 is then concentrated 6. This is achieved by any conventional means, for example by applying thermal energy and/or evaporation under vacuum.

The compounds extracted using supercritical CO2 extraction (second extract 7) are combined with the concentrated aqueous extract, step 8.

The concentrated aqueous extract 8 is preferably applied to the sheet after the sheet has proceeded through the pressing section, and before the sheet has proceeded through the drying section of the paper-making machine, step 13. The concentrated aqueous extract 8 may be applied to the sheet using spray coating, wetted rollers or any other method suitable in the art. Following this the sheet is dried 14.

The reconstituted tobacco product of the present invention may be used as a tobacco rod, suitable to be ensleeved by a wrapper such as a cigarette paper 15. The reconstituted tobacco product may be shredded to form a tobacco rod. Alternatively, the reconstituted tobacco product may be wrapped or folded to form a tobacco rod 15.

The reconstituted tobacco product of the present invention may also be used as a consumable, or part of a consumable, for an HNB device. It is a reconstituted tobacco product for use in an HNB device.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

Throughout this specification, including the claims which follow, unless the context requires otherwise, the word“comprise” and“include”, and variations such as“comprises”,“comprising”, and“including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

It must be noted that, as used in the specification and the appended claims, the singular forms“a,” “an,” and“the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from“about” one particular value, and/or to“about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent“about,” it will be understood that the particular value forms another embodiment. The term“about” in relation to a numerical value is optional and means for example +/- 10%.

Claims

1. A method for manufacturing a reconstituted plant material comprising the following steps:

extracting a fibrous plant material with a liquid solvent to provide a first extract and a fibrous portion;

separating the first extract from the fibrous portion;

forming a base sheet from the fibrous portion;

applying the second extract to the base sheet.

2. The method according to claim 1 comprising the steps:

concentrating the first extract to provide a concentrated extract; and combining the second extract with the concentrated extract before applying the second extract to the base sheet.

3. The method according to claim 1 or claim 2, wherein the liquid solvent is an aqueous solvent

4. The method according to any one of claims 1 to 3, wherein the fibrous plant material is

tobacco.

5. The method according to claim 4, wherein the tobacco is in the form of tobacco leaf, tobacco stem, tobacco powder, and/or tobacco dust.

6. The method according to any one of claims 1 to 5, wherein the supercritical carbon dioxide extraction pressure is within the range 74 to 350 bar, such as 74 to 200 bar.

7. The method according to any one of claims 1 to 6, wherein the supercritical carbon dioxide extraction temperature is within the range 31 °C to 100 °C, such as 40 °C to 80 °C, such as 40 °C to 60 °C

8. The method according to any one of claims 1 to 7, wherein the supercritical carbon dioxide contains 1 to 20 mol % of an entrainer.

9. The method according to any one of claims 1 to 8, wherein the supercritical extraction is countercurrent supercritical carbon dioxide extraction.