WO2019229704A1

WO2019229704A1 - Process for reducing nicotine in tobacco biomass and tobacco composition

Info

Publication number: WO2019229704A1
Application number: PCT/IB2019/054504
Authority: WO
Inventors: Steven Splinter; Tomasz Popek; Harmandeep KAUR; Anna BAKOWSKA-BARCZAK
Original assignee: Radient Technologies Inc.
Priority date: 2018-05-31
Filing date: 2019-05-31
Publication date: 2019-12-05

Abstract

A process is provided for obtaining nicotine-depleted tobacco without materially altering the appearance or flavor properties of the tobacco biomass. The method includes a microwave assisted extraction process that uses continuous flow of biomass and solvent through an extractor. The extraction solvent is continuously stripped of nicotine while remaining enriched in other tobacco extractable compounds, including flavor-related components, and is continuously recycled through the extractor. The microwave assisted extraction process includes a low residence time in the extractor, enabling the process to extract nicotine while minimizing physical degradation of the tobacco biomass. The process may also include, for example, methods of recovering and purifying the nicotine extracted from the biomass. A composition of nicotine-depleted tobacco is provided, where the nicotine-depleted tobacco maintains its original appearance and flavor.

Description

PROCESS FOR REDUCING NICOTINE IN TOBACCO BIOMASS AND TOBACCO

COMPOSITION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present patent application claims the priority benefit of U.S. provisional patent application number 62/678,704 filed May 31, 2018, the disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Disclosure

[0002] The present disclosure is generally related to tobacco biomass extraction process, and more particularly related to a method of preparing a composition of tobacco biomass that is depleted of nicotine and maintains the desirable properties of tobacco.

2. Description of the Related Art

[0003] Tobacco contains the alkaloid nicotine. Dried and cured tobacco leaves are mainly used for smoking in cigarettes, cigars, pipe tobacco, and related products. They can also be consumed as snuff, chewing tobacco, dipping tobacco and snus. Tobacco use is a risk factor for many diseases, especially those affecting the heart, liver, and lungs, as well as many cancers.

[0004] The term tobacco or "tobacco biomass" encompasses the genus Nicotiana and belongs to the Solanaceae (nightshade) family of plants, including the species N. tabacum, N. rustica, tobacco cultivars and tobacco chemovars (varieties characterized by chemical composition), and also plants which are the result of genetic crosses. The term "tobacco biomass" is to be interpreted accordingly as encompassing plant material derived from one or more tobacco plants.

[0005] All tobacco biomass used for consumable tobacco products contain nicotine and many other alkaloids. The concentrations of nicotine vary dramatically across different tobacco types and depend on plant genetics, country of origin, production year, agricultural practices such as fertilization and plant density in the field, curing and processing methods and storage practices. Manufacturers of tobacco products often use leaf blending to maintain consistency of nicotine in their products.

[0006] Tobacco-related harm ultimately results from addiction to the nicotine in such products, causing repeated use and exposure to toxicants in combusted tobacco. It is desirable to reduce the concentration of nicotine in these products to make them minimally addictive or non-addictive. Nicotine reductions in tobacco can be achieved through tobacco blending, cross-breeding, genetic engineering, and extraction. There are at least two disadvantages to using the blending, breeding or genetic engineering approach to reduce nicotine. First there may be a delay in the time that it would take to implement the necessary changes to the tobacco agricultural supply chain. Second, the blending, breeding or genetic engineering approach may yield unpredictable results. On the other hand, it may be more advantageous to use extraction approach to reduce nicotine from tobacco biomass because the nicotine concentration may be reduced to very low levels. In addition, after the nicotine is extracted from tobacco, a co-product may be purified nicotine. Purified nicotine has potential commercial value for inclusion in smoking cessation products, nicotine replacement products (e.g., e-liquids for use in e-dgarettes and vaping products), and as a fine chemical substrate in chemical and bioprocessing industries.

[0007] Conventional methods of nicotine extraction generally present substantial disadvantages and may yield undesirable product. For example, some conventional methods include extraction with water coupled with steam or oven drying. Other methods involve pretreating with alkaline substances and subsequent removal of nicotine by treatment with heat, steam or organic solvents. While effective in reducing nicotine concentrations, these conventional methods result in physical damage to the tobacco, which makes it unfit for production into desirable forms, such as cigarettes. In other cases, the methods result in the concomitant removal of other desirable components from the tobacco, such as those responsible for flavor and smell. Another conventional method of tobacco extraction is the use of supercritical fluid extraction (SFE) using carbon dioxide. However, SFE has many disadvantages. SFE requires specialized equipment to operate at very high pressures (> 70 atm). In addition, SFE is also an inefficient batch process and therefore not conducive to high throughput, and generates a large amount of the greenhouse gas carbon dioxide as a by-product.

[0008] Therefore, there is a need for an improved composition and an improved method for extracting nicotine from tobacco biomass that may reduce or eliminate physical degradation and substantially maintain the organoleptic properties of the tobacco.

SUMMARY OF THE CLAIMED INVENTION

[0009] This invention provides a method of selectively extracting nicotine from tobacco biomass and provides a composition of tobacco that is depleted in nicotine but retains the desirable properties of the tobacco. Tobacco biomass is continuously extracted using a solvent that is enriched with extractable compounds of tobacco biomass, but depleted in nicotine, thus providing a reduced driving force for extraction of the non-nicotine components of the tobacco. The nicotine is thus extracted from the tobacco biomass into the solvent, while the non-nicotine components remain. Thereafter, nicotine is continuously removed and recovered from the solvent and the solvent is recycled to extract nicotine from fresh, un-extracted tobacco biomass. In a preferred embodiment, the extraction is performed using microwave-assisted extraction, which reduces physical degradation of the tobacco biomass.

[0010] The present invention provides a process for obtaining a composition of nicotine- depleted tobacco without materially altering the physical integrity, appearance or organoleptic properties (e.g., aspects of food, water or other substances that an individual experiences via the senses— including taste, sight, smell, and touch) of the tobacco biomass. Further, the present invention provides methods of recovering and purifying the nicotine extracted from the tobacco biomass. Furthermore, the present invention provides a method for extracting nicotine and providing nicotine-depleted tobacco biomass and the recovery of the extracted nicotine in a continuous or cyclic manner. In addition, the present invention provides a method for extracting nicotine and providing a composition of nicotine-depleted tobacco biomass that is scalable to large processing volumes that is efficient and economical.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a block diagram representation of an exemplary system for extracting nicotine from tobacco biomass.

[0012] FIG. 2 is a flow chart illustrating an exemplary method for obtaining the composition of the tobacco biomass and purified nicotine.

[0013] FIG. 3 is a block diagram representation of an example case for extracting nicotine from tobacco biomass through repeated successive extractions.

[0014] FIG. 4 illustrates the exemplary results of nicotine depletion of raw tobacco biomass after repeated successive extractions.

[0015] FIG. 5 is the results of an example case of an extraction of tobacco biomass using a fresh solvent compared to a nicotine-free, flavor-concentrated solvent.

[0016] FIG. 6 illustrates the exemplary results of nicotine analyses of a solvent-extract mixture after contact with an ion exchange resin.

[0017] FIG. 7 illustrates the exemplary results of residual nicotine analyses for tobacco biomass after repeated successive extractions.

DETAILED DESCRIPTION

[0018] A method and a system for preparing a composition of nicotine-depleted tobacco biomass will now be explained with reference to various units shown in FIG. 1 and steps shown in FIG. 2. FIG. 1 is a block diagram representation of an exemplary system for extracting nicotine from tobacco biomass. FIG. 2 is a flow chart 200 illustrating an exemplary method for obtaining the composition of the tobacco biomass and purified nicotine. One skilled in the art will appreciate that, for this and other processes and methods disclosed herein, the functions performed in the processes and methods may be implemented in differing order. Furthermore, the outlined steps and operations are only provided as examples, and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations without detracting from the essence of the disclosed embodiments.

[0019] First, a nicotine-containing tobacco biomass (raw biomass) may be provided at step 202. It should be noted that prior to accepting the tobacco biomass, an inspection may be done to determine the quality of the tobacco biomass that may specifically search for any foreign material or defects that may be deleterious to the process. The raw biomass may be stored in a biomass holding chamber 102. The raw biomass may be present in the form of cured, cut filler tobacco. In other embodiments, the raw biomass may be comprised of cured tobacco strips or any other suitable form of tobacco. The raw biomass is sampled and analyzed at step 204 in the sampling chamber 128. The raw biomass may be further prepared at step 206 in the biomass preparation chamber 104 by undergoing other preprocessing steps that might assist the overall process, such as being cut or chopped or ground to certain levels. It may be useful to have as much of a homogenous tobacco biomass as possible. The prepared biomass is stored at the prepared biomass holding chamber 106.

[0020] A solvent or extractant may be added to the prepared biomass at step 208. The solvent may be stored in a solvent holding chamber 110. In an embodiment, the solvent may be a nicotine-depleted extract solution of tobacco that is enriched in tobacco extractable compounds, or components of tobacco biomass other than nicotine that are able to be extracted by the solvent. [0021] The solvent may be any solvent capable of extracting nicotine from tobacco, including water, supercritical fluids or lower alcohols such as methanol, ethanol or isopropanol, or mixtures of lower alcohols with water. In some embodiments the solvent may be acidified to a pH of about 2 to 5. In some embodiments, the solvent is ethanol saturated with tobacco extractable compounds other than nicotine and depleted of nicotine. In an embodiment the solvent is a mixture of 80% ethanol and 20% water (v/v) that is enriched in tobacco extractable compounds other than nicotine and has been acidified to a pH of about 2.5 to 3. In a preferred embodiment the solvent is a mixture of 80% ethanol and 20% water (v/v) that is enriched in tobacco extractable compounds other than nicotine. It should be noted that to those skilled in the art, the ratio of ethanol to water can change for enhancing the process, for instance the concentration of ethanol may be between 60% and 90%.

[0022] In a preferred embodiment, the solvent is a nicotine-free tobacco extract solution whose concentration of tobacco extractable compounds is so high that the solution extracts only nicotine from the tobacco biomass. When the tobacco extractable compounds are not very high, then the solution may not extract only nicotine from the tobacco biomass. In this case, the extracted tobacco may be diminished in certain organoleptic properties such as taste and aroma. It should be also noted (not shown) that at this point in the process a sensor can be used on the solution extract to detect the amount of nicotine, for instance based upon using electrochemical sensing of nicotine using screen-printed carbon electrodes modified with nitrogen-doped graphene sheets. In this way, calculations can be made as to the effectiveness of the extraction.

[0023] Successively, the raw biomass and solvent may be sampled and analyzed. The raw biomass and solvent may be sampled in a sampling chamber 128. The raw biomass and solvent may be sampled and analyzed using several sampling techniques. In a preferred embodiment, the raw biomass may be sampled and analyzed for determining nicotine content and moisture content. The raw biomass may be analyzed using a Gas

Chromatography method (GC). In an embodiment, the solvent is sampled and analyzed for determining nicotine content. Nicotine analysis may be performed using High Performance Liquid Chromatography method (HPLC). The sampling and analyzing techniques may help in selecting the most suitable extraction conditions to selectively deplete nicotine from the raw biomass. The solvent-to-biomass ratio may be about 5 to 50 liters per kg of tobacco biomass. In a preferred embodiment, the solvent-to-biomass ratio is 20 liters per kg of tobacco biomass. The solvent-to-biomass ratio can change based upon for example the bulk density of the tobacco biomass or the nicotine content of the tobacco biomass and this value can be adjusted to help provide quality control.

[0024] Successively, the raw biomass and solvent may be transferred to an extractor in an extraction chamber 112 at step 210. The extraction chamber 112 may be based upon any known solid-liquid extraction apparatus known in the art, including but not limited to percolation-type extractors, immersion-type extractors, carousel extractors, screw extractors, or counter-current flow-type extractors. In a preferred embodiment, the extractor is a continuous-flow extractor. The raw biomass and solvent mixture may be subjected to a thermal process, for example microwave heating by a microwave generator 114. There could be other forms of heating known in the art such as steam heating, laser heating, plasma heating, etc. The extractor may transport the biomass and solvent mixture through the extraction chamber 112. At least one portion of the chamber 112, or the entire chamber 112, may be microwave transparent (i.e. a material property that allows microwaves to pass through the material without being significantly absorbed or reflected). In an embodiment, the extraction chamber 112 is filled completely with the solvent to remove air and other gases. In some embodiments, the extraction chamber 112 may be purged with an inert gas such as nitrogen prior to the extraction process to remove air and other oxidizing gases. In some embodiments, temperature sensors can be placed in or travel with the biomass to get real time feedback and control of the temperature.

[0025] The raw biomass and solvent mixture may be heated to a certain temperature by exposing the raw biomass and solvent mixture to the microwave generator 114 to a predefined time, with a predefined controlled microwave energy density range. It should be noted that the microwave energy can be measured and used in a feedback control to maintain temperature. In a preferred embodiment, the raw biomass and solvent mixture may be heated to a temperature range of 20 to 90° C with a contact time of about 1 to 15 minutes and microwave energy density range of 0.1 to 10 kW/kg. Contact time is controlled by the feed rate of the tobacco biomass, the solvent, and the volume of the extraction chamber 112. In a preferred embodiment, the raw biomass and solvent mixture may be heated to about 80° C with a contact time of about 5 minutes and microwave energy density of approximately 7 kW/kg. The extraction chamber 112 may be a continuous flow extractor that may reduce residence time (i.e., less than 5 minutes) of the biomass in the raw biomass and solvent mixture, between the heat, the solvent and the biomass, the time that the solvent may be in contact with the biomass.

[0026] Although contact time is a control parameter, contact time may vary due to the heat, the solvent, and the biomass variations. Furthermore, the application of microwave energy to the system may result in instant volumetric heating that may affect the control of temperature and time of exposure of the raw biomass to the solvent. By limiting contact time with the solvent, it may be possible to reduce physical degradation of the tobacco biomass caused by prolonged contact with the solvent and may reduce swelling and physical damage to the tobacco biomass.

[0027] Post extraction, the biomass and extract mixture may be separated at step 212 in the separation chamber 116. Such separation may be performed using filtration,

centrifugation, or other similar processes known in the art. In a preferred embodiment, the separation may occur in stages, with first stage separation occurring in the extraction chamber 112 via drainage of the solvent from the tobacco biomass at certain sections in the extraction chamber 112 and second stage separation occurring in the separation chamber 116 with a continuous flow filter dryer. In a preferred embodiment, the second stage separation allows for controlled removal of solvent from the extracted tobacco biomass to provide a nicotine-depleted tobacco product with residual solvent less than about 100 ppm to 1000 ppm of solvent and a moisture content of about 10% to 15%. Within this critical parameter range, a moisture content measurement can be taken of the nicotine-depleted tobacco product that contains residual solvent. The data can be used to control the process.

[0028] The biomass may be treated in a biomass treatment chamber 118 by undergoing various steps to acquire a final product. Such treatment may include drying or moistening of the tobacco biomass to the desired moisture level. In an embodiment, the residual solvent in the extracted tobacco biomass may be recovered by using a vacuum distillation or vacuum evaporation process. The use of recovering the solvent is useful for lowering the cost and minimizing environmental impact. However, the recovered solvent should be sampled or measured real time to insure the quality of the process. Upon recovery, the solvent may be recycled for use in another extraction process. The final biomass product may be stored in a biomass product holding chamber 120.

[0029] The separated tobacco biomass product may be sampled and analyzed at step

214. The sampling of the biomass may be performed by the sampling chamber 120. The extracted tobacco biomass product may be analyzed using several analysis techniques. In an embodiment, the extracted tobacco biomass product may be analyzed for determining residual nicotine content. Nicotine analysis may be performed using a Gas Chromatography- method (GC).

[0030] Post separation from the tobacco biomass, the solvent extract mixture may be processed to recover the alkaloid (e.g. nicotine) in step 216 and stored in the alkaloid recovery chamber 122. The solvent may be recycled to the solvent holding chamber 110 to be used in another extraction process. The recovered solvent should be sampled or analyzed real time to insure the quality of the solvent.

[0031] In an embodiment, the nicotine is recovered from the solvent in a continuous fashion. Removal of nicotine and other alkaloids from the solvent can be accomplished by any method known in the art, including but not limited to use of an acid trap, liquid-liquid separation, precipitation, absorption on acidic sorption material, or capturing on an ion exchanger. In an embodiment, an acid trap is used where the acid is impregnated on a support medium, such medium including but not limited to tobacco filler, tobacco stems, cotton, cellulose, carbon, porous ceramic, or porous metal. In passing through the acid trap, the nicotine in the solvent reacts with the acid and is captured by the acid trap. Preferable adds are those which are non-volatile and non-soluble in the extraction solvent, including, but not limited to, sulfuric acid, phosphoric acid, or nitric acid. In another embodiment, nicotine and other alkaloids can be removed by continuous liquid-liquid extraction of the solvent with a second immiscible solvent that is an acceptable solvent for nicotine, preferably with pH adjustment to basic conditions. In another embodiment, nicotine can be removed by an adsorption agent on an adsorption column. In a preferred embodiment, the adsorption agent is preloaded with tobacco extractable substances other than nicotine in order to minimize removal of such substances by the adsorption agent. In one embodiment, the adsorption agent is pre-loaded with substitute substances having a molecular size and structure similar to the tobacco extractable substances other than nicotine. In a preferred embodiment, nicotine and other alkaloids are removed from the solvent by ion exchange. In an embodiment, the ion exchange medium is a mineral. In a preferred embodiment, the ion exchange medium is an acidic resin, for example DIAION UBK550 or DIAION UBK555.

[0032] Successively, the extracted alkaloid ( e.g . nicotine) may be further purified at step 218 in an alkaloid purification chamber 124. Purification of nicotine may be accomplished by any method known in the art, including but not limited to distillation, crystallization, liquid- liquid extraction or chromatography, or any combination of such techniques. The final purified nicotine product is stored at the alkaloid holding chamber 126.

[0033] The purified nicotine product stored in the alkaloid holding chamber 126 may be sampled and analyzed at step 220 in the sampling chamber 120. The purified nicotine product may be sampled using several sampling techniques. In an embodiment, the purified nicotine product may be sampled and analyzed for nicotine purity. Nicotine analysis may be performed using a Gas Chromatography-method (GC).

[0034] In an alternative embodiment, steps 208 to 212 may be a cyclic repeated process. After the solvent is added to the prepared biomass in step 208 and goes through the extraction step 210 and separation step 212, the biomass may be returned from the separation chamber 116 to the extraction chamber 112, instead of being transferred to the biomass treatment chamber 118. The solvent-extract mixture may be transferred to the alkaloid recovery chamber 122 in step 216. After the alkaloid is recovered from the solvent, the solvent is stored in the solvent holding chamber 110 to be recombined with the previously extracted biomass. This cycling process may be repeated for any number of successive extraction-separation steps in order to deplete the tobacco biomass of nicotine. The benefits of repeating the successive extraction-separation steps for a single batch of biomass are to increase alkaloid depletion while limiting the contact time between solvent and biomass to reduce risk of damage to the biomass.

[0035] FIG. 3 is a block diagram representation of an example case of extracting nicotine from tobacco biomass through repeated successive extraction. In this example case, 50 grams of raw tobacco biomass in the form of cured strips is stored in the prepared biomass holding chamber 302 and is sampled and analyzed by Gas Chromatography analysis. An analysis shows that the biomass contains 2.48% (w/w) nicotine. The 50 g of tobacco biomass is extracted with a solvent that consists of 1500 mL of 80% ethanol / 20% water (v/v) adjusted to a pH of 2.5 by addition of hydrochloric add during exposure to 7 W/g of microwave energy for 4 minutes. This is the first round of extraction of the 50 g of tobacco biomass (Extraction Stage 1). The extracted biomass is separated from the extract solution by filtration in the separation chamber 310 and returned to the extraction chamber 306. The filtrate is cooled to room temperature and filtered to remove any precipitated material. The extract solution is passed over an ion exchange column packed with a protonated strong cationite ion exchange resin to remove nicotine in the alkaloid recovery chamber 312. The nicotine-free extract solution is then recycled back to a solvent holding chamber 314 and directed to the extraction chamber to be combined with the extracted biomass from Extraction Stage 1. The previously extracted biomass from Extraction Stage 1 will be extracted a second time using the same extraction conditions (Extraction Stage 2). The same experimental conditions are repeated for a third extraction of the same extracted biomass from Extraction Stage 2 (Extraction Stage 3). After each Extraction Stage, samples of the triple-extracted tobacco biomass are collected and analyzed for residual nicotine content using a Gas Chromatography method (GC). The result of this example case is shown in FIG. 4.

[0036] FIG. 4 illustrates the exemplary results of nicotine depletion of raw tobacco biomass after repeated successive extractions from the exemplary case shown in FIG. 3. FIG.

4 shows the residual nicotine analyses of the tobacco biomass after each Extraction Stage 1 to 3. The nicotine concentration after each successive Extraction Stage shows successive depletion of nicotine. The raw biomass is analyzed to show nicotine concentration of 2.48% w/w. After Extraction Stage 1, the nicotine concentration is 0.69 % w/w. After Extraction Stage 2, the nicotine concentration is 0.17 % w/w. After Extraction Stage 3, the nicotine content of the nicotine-depleted tobacco product is 0.06% w/w, representing an approximate 98% reduction in the original nicotine content of the raw tobacco biomass. The final nicotine- depleted tobacco product was dried to a moisture content of 12%. The final nicotine-depleted tobacco product retains the physical characteristics of the starting material, including being relatively moist and non-brittle, retaining the same approximate color as the raw tobacco biomass and showing no obvious signs of clumping, aggregation or other forms of physical degradation. Qualitative testing indicates that the tobacco biomass retains much of the expected aroma and flavor of the original raw tobacco biomass. [0037] FIG. 5 is the results of an example case of the successive extraction of tobacco biomass using a fresh solvent compared to a flavor-concentrated solvent. The extracted biomass is analyzed for the extracted nicotine and components responsible for flavor and aroma in tobacco biomass. The fresh solvent does not contain compounds responsible for the flavor and aroma of tobacco.

[0038] In the extraction with fresh solvent, the raw tobacco biomass was mixed with 80% ethanol / 20% water (v/v). Nicotine and compounds responsible for flavor and aroma were extracted from the raw biomass during the exposure to 4.45 W/g of microwave energy for 10 minutes. The extracted biomass was separated from the extract solution by filtration. The filtrate was cooled to room temperature and filtered again to remove any precipitated material. The extract solution was analyzed for nicotine by Ultra-High Performance Liquid Chromatography with Mass Spectrometry (LC-MS) and for four components responsible for the characteristic flavor and aroma of the tobacco (2-Furanmethanol, 4H-pyran-4- one_/2,3dihyrdo-3,5-dihydroxy-6-methyl-, vanillin and 2(3H)-Furanone, dihydro-4-hydroxy-) by Gas Chromatography with Mass Spectrometry (GC-MS). The extract solution was then used as the solvent to repeatedly extract more raw tobacco biomass using the same conditions as the first extraction in order to concentrate solvent in components extractable from tobacco. The concentrated extract solution then passed over an ion exchange column packed with an ion exchange resin (DIAION UBK 550 resin, previously activated by acidifying with IN hydrochloric acid) to remove nicotine.

[0039] Using the same test conditions as fresh solvent, a nicotine-free flavor concentrated solvent is used to extract raw tobacco biomass. The extract solution after extraction of the tobacco biomass with the nicotine-free flavor concentrated solvent was analyzed for nicotine by Ultra-High Performance Liquid Chromatography with Mass Spectrometry (LC-MS) and for four components responsible for the characteristic flavor and aroma of the tobacco (2-Furanmethanol, 4H-pyran-4-one,2,3dihyrdo-3,5-dihydroxy-6- methyl-, vanillin and 2(3H)-Furanone, dihydro-4-hydroxy-) by Gas Chromatography with Mass Spectrometry (GC-MS).

[0040] FIG. 5 shows a comparison of the LC-MS peak areas for nicotine and the GC-MS peak areas for the four flavor and aroma components for the extraction solution after extraction with fresh solvent and the extraction solution after extraction with flavor- concentrated solvent. The peak areas of LC-MS and GC-MS chromatograms are proportional to the amount of each compound in the sample. For each solvent, the concentration of nicotine in the extract is approximately the same. However, the concentrations of flavor components extracted are severely reduced when using a nicotine-free flavor-concentrated solvent. The results indicate that the biomass retains its flavor profile when a flavor concentrated solvent is used as compared to the fresh solvent.

[0041] FIG. 6 illustrates the exemplary results of nicotine analyses of a solvent-extract mixture after contact with an ion exchange resin. First, a nicotine-free tobacco extract solution was prepared by exhaustively extracting raw tobacco biomass with 80% ethanol / 20% water (v/v). The extracted biomass was separated from the extract solution by filtration and the extracted biomass discarded. The extract solution was passed over an ion exchange column packed with a protonated strong cationite ion exchange resin. The saturated extract solution was sampled and analyzed by HPLC and found to be free of nicotine.

[0042] 50 g of raw tobacco biomass in the form of cured strips was mixed with 1500 mL of the prepared nicotine-free extract solution. Nicotine was extracted from the raw biomass during the exposure to 4.45 W/g of microwave energy for 10 minutes (Extraction Stage 1).

The extracted biomass was separated from the extract solution by filtration; the filtrate (1240 mL) cooled to room temperature and filtered again to remove any precipitated material. The extract solution was passed over an ion exchange column packed with an ion exchange resin (60 g of DIAION UBK 550 resin, previously activated by acidifying with IN hydrochloric add; 6 mL/min flow) to remove nicotine. The nicotine-free extract solution was combined with the extracted biomass from Extraction Stage 1 and extracted a second time using the same extraction conditions (Extraction Stage 2). The nicotine from Stage 2 extract solution (1 L) was removed by passing through 30 g of ion exchange resin (DIAION UBK 550, previously activated by acidifying with IN hydrochloric acid, 5 mL/min flow). Experimental conditions were repeated for a third extraction (Extraction Stage 3). 35.8 g of final nicotine- depleted tobacco product was collected. Samples of the solvent extract mixture were collected after each extraction stage before and after passing on the ion exchange column and analyzed for nicotine content by HPLC. Samples of the extracted tobacco biomass were collected after each extraction stage and analyzed for residual nicotine content using a Gas Chromatography method (GC). FIG. 6 shows that the solvent is nicotine-free after each ion exchange.

[0043] FIG. 6 shows the results of analyses of the solvent-extract mixture at various steps in the process. Nicotine is extracted into the solvent-extract mixture after each extraction stage and is completely removed after contact with an ion exchange resin. The nicotine concentration in the nicotine-free solvent-extract mixture decreases after each extraction stage as the tobacco biomass is successively depleted of nicotine. The HPLC peak area indicates the relative amount of nicotine present in the mixture. After Extraction Stage 1 to 3, the nicotine HPLC peak areas show successively decreasing amounts of 5141.7, 1367.0, and 355.6 respectively. Each time the solvent from Extraction Stage 1 and 2 comes into contact with an ion exchange resin, the nicotine content within both solvents is zero.

[0044] FIG. 7 illustrates yet another exemplary result of residual nicotine analyses for tobacco biomass after repeated successive extractions. FIG. 7 shows the results of residual nicotine analyses for the triple-extracted tobacco biomass sampled and analyzed after each extraction stage. After Extraction Stage 3, the nicotine content of the nicotine-depleted tobacco product was 0.04% w/w, representing a more than 98% reduction in the original nicotine content of the raw tobacco biomass. The final nicotine-depleted tobacco product retained the physical characteristics of the starting material, including being relatively moist and non-brittle, retaining the same approximate color as the raw tobacco biomass and showing no obvious signs of clumping, aggregation or other forms of physical degradation. Qualitative testing indicated that it retained much of the expected aroma and flavor of the original raw tobacco biomass.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method for depleting alkaloid from a composition of tobacco biomass, the method comprising:

preparing a raw tobacco biomass;

forming a mixture by adding a liquid extraction solvent to the prepared raw tobacco biomass;

extracting alkaloid from the raw tobacco biomass into the liquid extraction solvent using a continuous flow heat assisted extraction apparatus;

separating the alkaloid-depleted tobacco biomass from the liquid extraction solvent; and

removing alkaloid from the liquid extraction solvent.

2. The method of claim 1, further comprising recycling the liquid extraction solvent from which alkaloid has been removed to the continuous flow heat assisted extraction apparatus.

3. The method of claim 1, wherein the alkaloid is nicotine.

4. The method of claim 1, wherein the heat assisted extraction apparatus is a microwave assisted extraction apparatus.

5. The method of claim 4 wherein microwave energy density of the microwave assisted extraction apparatus is between 0.1 kW/kg and 10 kW/kg.

6. The method of claim 1, further comprising heating the mixture to a temperature range of between 20 degrees Celsius and 80 degrees Celsius for a contact time of between 1 minute and 15 minutes.

7. The method of claim 1, wherein removing the alkaloid from the liquid extraction solvent includes use of at least one of acid trap, liquid-liquid separation, precipitation, absorption on addic sorption materials, or ion exchange.

8. The method of claim 1, further comprising purifying the alkaloid removed from the liquid extraction solvent.

9. The method of claim 1, wherein the alkaloid is removed from the liquid extraction solvent in a continuous fashion.

10. The method of claim 1, further comprising processing the alkaloid-depleted tobacco biomass.

11. The method of claim 10, wherein processing the alkaloid-depleted tobacco includes drying or moistening to moisture level of between 10% and 15%.

12. The method of claim 1, wherein the liquid extraction solvent is enriched in extractable tobacco components but depleted of nicotine.

13. The method of claim 1, wherein the liquid extraction solvent consists of at least one of water, supercritical fluids, methanol, ethanol, and isopropanol.

14. The method of claim 1, wherein the liquid extraction solvent includes a mixture of ethanol and water.

15. The method of claim 14, wherein the ratio of ethanol to water in the liquid extraction solvent is between 60% and 90% v/v.

16. The method of claim 1 wherein the pH of the liquid extraction solvent is between 2 and 5.

17. A composition of tobacco biomass, the composition comprising less than 0.06% (w/w) of nicotine concentration.

18. The composition of claim 17 wherein the composition maintains its organoleptic properties.

19. The composition of claim 17, wherein the composition shows no signs of physical degradation.