AU612128B2

AU612128B2 - Process for removal of basic materials

Info

Publication number: AU612128B2
Application number: AU83109/87A
Authority: AU
Inventors: Harvey Joseph Grubbs; Tony M. Howell; Ravi Prasad
Original assignee: Philip Morris Products SA
Current assignee: PHILIP MORRIS PRODUCTS Inc
Priority date: 1986-12-29
Filing date: 1987-12-29
Publication date: 1991-07-04
Anticipated expiration: 2007-12-29
Also published as: EP0280817A2; AU8310987A; ZA879384B; JPS63229102A; FI88453C; EP0280817B1; CA1317961C; JP2694253B2; BR8707110A; FI88453B; FI875673A; DE3789300D1; EP0280817A3; ATE102446T1; FI875673A0

Abstract

A process is provided for the selective removal of basic materials from plant products, in particular, for removing nicotine from tobacco without materially affecting the content of the other components of the tobacco. Tobacco is traversed with a solvent in the supercritical state or in the liquid state wherein nicotine and the other components dissolve in the solvent. The solvent is then passed through an acid-containing trap where the solvent is essentially freed of nicotine. The solvent, depleted of nicotine and enriched in the other components, is then recycled to the tobacco to reextract nicotine. In addition, the tobacco may be pretreated with a chemical base which does not substantially react withe the tobacco components under ambient conditions but rather is activated under the conditions of the extraction process. Pretreatment of the tobacco with a chemical base neutralizes nicotine salts and permits the extraction process to be carried out under milder conditions.

Description

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I

Australia Form PATENTS ACT 1952 COMPLETE SPECIF11."IATION (OR IG INAL) FOR OFFICE USE 612128 Short Title: Int. Cl, Application Number: Lodged: ornplete Specification-Lodg~ed: Ac.cepted: Lapsed; Published; Priority: Pelated Art,, Name of Applicant: Address of Applicant: Actual Inventor;, Address for Service' TO BE COMPLETED BY APPLIICANT of America 'United States HARVEY J. GRUBBS, RAV, VRAGAD and TONY N. HOWELL CALIJNANS Patent Attorneys, of 48-50 Bridge Road, Richmond, State of Victoria, Australia.

Comrlete Specification for the invention entitled: "PROCESS FoR, REMOVAL OF BASICO MATERIALS" The following statement Is a full description of this finvention, Including the best method of performing It known to me.- Note: The description Is to be typed, In double spacing, pica typo face, In an area not exceeding 250 mm lin depth and 100 mm In width, on tough white paper or good quality and It Is to bo Inserted Inside this form, iu u

ONEHUDEDOLR

To: The Commissioner of Patents.

I I' 1 r t la PROCESS FOR REMOVAL OF BASIC MATERIALS gi e.

C.

S.

S

C

SS C 5 Field of the Invention This invention relates to extraction procedures and is particularly directed to a process for the selective removal of basic materials from plant products. The invention may be used for the selective extraction of particular substances from a great variety of plant products. However, it is particularly applicable and will therefore be described in connection with the extraction of nicotine from tobacco.

15 Background of the Invention Various processes have been proposed for the removal of nicotine from tobacco. Most of these processes, however, are not sufficiently selective for nicotine and remove other ingredients from the tobacco. Removal of these other ingredients adversely affects the desirable flavor and aroma properties of the tobacco. Other processes generally have been found to be limited in their scope and effectiveness and are often complex and expensive to carry out.

Nicotine has been extracted from tobacco using organic solvents with and without neutralization of the nicotine salt. Representative of such pro- Declared at Richmond,Virginia this 13th day of March 1990.

USA

Signed: Patsy VKei, Assistant Secretary, Philip Morris Products Inc.

t cesses are those disclosed in U.S. Patent Nos. 678,362 (Froehling), 1,196,184 (Villiers-Stuart), 2,048,624 (Roselius), 2,128,043 (Garner), 2,227,863 (Rhodes) and 3,096,773 (Prilly et-al.). Nicotine has also been extracted from tobacco with aqueous solutions with and without neutralization of the nicotine salt.

Representative of such processes are those disclosed in U.S. Patent Nos. 2,822,306 (Beuel et al.), 2,582,075 (Severi) and 3,874,392 (De Brunn et al.).

Nicotine has been separated from solutions of tobacco extracts and the nicotine depleted solvent returned 0 to the tobacco. Representative of such processes are those disclosed in U.S. Patent Nos. 283,622 (Liebreich et 802,437 (Wimmer), 2,805,667 (von Bethmann), 3,046,997 (Hind), and 3,139,435 (Staley et Nicotine has also been separated from solutions of tobacco extracts and the depleted srlvent saturated with the other components recycled to the extraction vessel. Representative of such processes 20 are those disclosed in U.S. Patent Nos. 1,294,310 (Sayre et 1,577,768 (Smith), 1,813,333 (Andrews), 3,396,735 (von Bethmann) and 3,612,066 ""(Jones).

Nicotine has been transferred from tobacco to a substrate without the use of a solvent by contacting tihe tobacco intimately with a substrate which has been treated with an acid as disclosed in United States Patent No. 4,215,706 (Larson). This process maybe carried out with or without heat.

United States Patent No. 4,153,063 (Roselius) discloses a process for removing nicotine from tobacco in which tobacco is contacted with an extraction solvent in a supercritical state. In a single step extraction process,'moist tobacco is extracted with a solvent in a supercritical state. Thereafter the solvent is evaporated. Because aroma components are also removed along with nicotine in this single stelp I a -3extraction process, a multi-step process has been suggested. In the first step, dry tobacco is extracted with a solvent in the supercritical state to remove the aroma components. In the second step, the tobacco is moistened and again extracted with a solvent in the supercritical state to remove nicotine which is separated by either evaporating the solvent, contacting the solvent in a separate vessel with an acid, or absorbing the nicotine on an active carbon column. In the third step, the stored aroma components from the first step are redissolved in a supercritical solvent and returned to the tobacco. This multi-step extraction process is expensive and time consuming. In addition, the prolonged handling of the aroma "I I components may adversely affect their I L fperties.

In one aspect of the invention there is provided a method for the selective removal of at least one basic component from a solvent in an extraction o O process, wherein said basic component is extracted fro. a material together with a plurality of other substances by a solvent at a high pressure, said solvent being in a physical state which is either a liquid at a pressure of 50 to 300 atmospheres or a supercritical fluid at a temperature from the critical temperature of the solvent to 120 C and a pressure of 70 to 1500 atmospheres, said component being removed from the extraction solvent by contacting said solvent directly following the extraction of said material and in the same physical state, with a non-volatile acid which is not soluble in the solvent and which selectively removes the basic component without removing the other substances contained in the same solvent..

Preferably the basic component is nicotine which is derived from tobacco by extraction with a normally gaseous solvent in the presence of at least by weight of moisture, based on the weight of the tobacco and wherein nicotine is selectively removed from the solvent by the non-volatile acid while preserving aroma-producing components.

Preferably the moisture content of the tobacco is up to 30% by weight.

*r.

-4- In a further aspect of the invention there is provided a method for the selective removal of at least one basic component from a plant product containing a plurality of substances including acid salt forms of said basic component, wherein said plant product is first contacted with a 'chemical base which does not substantially react under ambient conditions with the acid salt forms of said basic component or with other plant comp its but can react with the said acid salts under the conditions of an extractiot, process, and the plant product is then contacted with an extraction solvent in a physical state which is either a liquid at a pressure of 50 to 300 atmospheres or a supercritical fluid at a temperature from the critical temperature of the solvent to 120'C and a pressure of 70 to 1500 atmospiheres, the conditions being such that the chemical base does react with the acid salt forms of the basic component in the plant product.

iPreferably the abovementioned method is for the selective extraction of nicotine from tobacco while preserving aroma-producing components, wherein the chemical base does not significantly react with acid salts of nicotine under ambient conditions but does react with the nicotine salts under the extraction conditions, and wherein the tobacco is extracted with a normally gaseous solvent in the presence of at least 10% by weight of moisture based on the weight of the tobacco.

*s e r Brief Description of the Drawing FIG. 1 illustrates the apparatus for removing basic materials.

Detailed Description of the Invention FIG.1 illustrates one preferred apparatus for removing nicotine from tobacco and tobacco blends. Extraction vessel 1 is filled with a sample of tobacco and entrapment vessels 2 and 3 are filled with an acid impregnated support medium or water, preferably containing some acid. An extraction solvent is supplied to vessel 1 which is connected to a pump 4 and a mass flow meter The pressure in the vessel is controlled by means of a fill pump (not shown) and the temperature is controlled by means of heat exchanger 6. The extraction solvent enters the top of the extraction vessel, passes downwardly through the sample and leaves at the bottom of the vessel. In passing through the sample, the extraction solvent becomes enriched with components of the sample. The solvent is then circulated through either trap 2 or trap 3, or both, again being introduced from the top, and then passing downwardly and exiting at the bottom, The entrapment time may be split between traps 2 and 3. In passing through the trap or traps, the nicotine in the solvent reacts with the acid and becomes trapped therein while the remaining aroma components in the solvent pass through the trap or traps freely. The solvent, depleted of nicotine and enriched in the other components, is then returned into the cycle by recirculating it to the extraction vessel.

S* *i 0 5 *o urwS The extraction vessel is preferably designed for radial flow or for axial flow of solvent. The entrapment vessels are preferrably both designed for radial flow or axial flow but need not be of the same design as the extraction vessel. A radial flow of solvent will minimize compaction of solid material in i vessel and may allow for lower pressure drops within each vessel. Persons skilled in the art will recognize that many directions of flow will be effective, flow from bottom to top, top to bottom or inward or ouitward radially in each vessel. Persons skilled in the a~rt will also recognize that the pump be placed on any of several lines in the system, An especially preferred procedure makes it 15 possible to contain both the tobacco sample and a relatively small volume of entrapment material in same extraction vessel, In this procedul-e, the entrapment material is placed in the bottom portion :4 of the extraction vessel, a porous plate is placed 20 on top of the trap and the tobacco is loaded into the extraction vessel on top of and supported by the 4 porou,. ~late. The entrapment vessel' 2 and 3 are ~.removed from the flow 5ystem by valve adjustment.

The extraction of the tobacco sample is then carried 25 out as before by introducing the solvent ioto the top of the extraction vessel and passing it downwardly through the sample until iL exits at the bottom of the vessel.

One advantage of this process is that no additional vessel is necessary to contain a relatively large quantity of adsorption material to trap the nicotine, The ability to carry out the extraction in a single ve;5sel rxesults in a more economical process for the above reasons and also because the solvent to tobacco ratio can be significantly lowered.

The ability to use 1(,ss solvent also r~esul~ts in less degradation and loss of the aromi producing components and consequently in an improved tobacco product.

In another embodiment of this invention, the tobacco may be pretreated with a chemically basic compound which does not significantly react with the tobacco components under ambient conditions but rather is activated under the conditions of the extraction process. Nicotine is thus 1, erated from its salts and immediately taken up in the extraction solvent before other base induced chemistry is initiated within the tobacco. Since the solubility of the nicotine free base is generally higher than that of the nicotine salts in the extraction solvents *W of choice, the extraction process may be carried out 15 under milder conditions. Pretreatment can include spraying or soaking the tobacco with the basic coma. pound or a suitable solution. thereof.

Persons skilled in the art will recognize that the said chemically basic compounds include those which are not necessarily affected by the process conditions but are nonetheless effective in increasing the amount of nicotin which can be S""extracted by the process of this invention.

A number of extraction solvents having solvent capacity for nicotine in both their liquid and gaseous phases can be employed to reduce the :nicotine content of tobacco. Carbon dioxide in the supercritical state is the preferred solvent in this invention. Other useful solvents include, for example, halogenated hydrocarbons including up to about 4 carbon atoms ouch as CF 4

CHF

3

CCIF

3 CBrF 3

CFZ=CH

2

CF

3

-CF

2

CF

3

CNCIF

2 CC1 2

F

2 CHC1 2 F, CCI 3

F,

CBrF 3

CFCI=CF

2

CH

3

-CF

3 octafluorocyclobutane and hydrocarbons including up to about 5 carbon atoms such as propane, butane, pentane; other useful solvents include N 2 0, SF 6 and argon. Mixtures of solvents or additives or co-solvents may be used to obtain improved solvent characteristics. In addition, water, ammonia, or aqueous ammonia can be mixed with the extraction solvent to obtain imiproved solvnt characteristics. Carbon dioxide is the preferred solvent because it is a naturally occurring compound and leaves no non-tobacco residue in the extracted tobacco.

A solvent in the supercritical state is a iolvent in the gas phase at a sufficiently high temperature so that it cannot be liquified by an increase in pressure. A solvent in the subcritical state is a solvent which can be liciified by an incvease in pressure.

.Supercritical carbon dioxide iF carbon 15 dioxide which is above its critical temperature, o°° above 31,30C, and above its critical pressure, above about 70 atmospheres. Extraction with carbon dioxide in the supercritical state is carried out at a pressure in the range of from about 70 to 20 about 1500 atmospheres and at a temperature in the range of from just above the criti.cal temperature to 0 about 120 0 C. The range of temperature and pressure for the supercritical state of other useful solvets 0. •are of generally the same order of magnitude.

The preferred acids for use in this invention are acids which are non-volatile and non-soluble in the extraction solvent under the conditions of the extraction. Useful acids are sulfuric, phosphoric and nitric. Other useful acids include polycarboxylic acids such as tartaric, citric, malic, malonic, succinic and glutamic. Monovalent salts, such as the alkali metal salts, of the above acids are generally preferred because these salts are less volatile and less soluble in the solvent. A preferred salt of an acid is monopotassjum citric acid. Monoammonium and diammonium salts of the above acids may also be used, Polyvalent salts of the above acids are also useful but are less efficient in trapping nicotine.

The acid in the trap is preferably, though not necessarily, in contact with a support medium, which does not impede the flow of the solvent. The acid may be impregnated on, deposited on, or otherwise in contact with the support medium. Useful support media are carbon, tobacco filler, reconstituted leaf materials, tobacco stems, cotton cloth, cellulose, cocoa shells, other plant by-pioducts, porous ceramic, porous metal and the like. The tobacco stems may be long stems, cut and rolled, shredded, expanded, treated or untreated. Especially preferred support media are shredded tobacco stems and cocoa shells.

The support medium for the acid may even be water, as in the case where the solvent is bu.0bled through an aqueous solution of the acid. A preferred trap materl i-,s an aqueous solution of citric acid.

An especially preferred trap material is an aqueous 20 solution of monopotassium citrate.

ratio of acid to nicotine may range from about 10:1 to about 1:1 and preferably from about 4.5:1 to 1.5:1.

The concentration of the acid in the support medium is not critical. The concentration should be high enough to minimize the volume of support medium required within the vessel but low enough not to impede the flow characteristics of the solvent through the support medium. The concentration of acid in the siupport medium may vary but in the case of tobacco stems the concentration generally ranges from about by weight to about 40% by weight and preferably is about 15% ;y weight. Higher acid concentrations, saturated or crystalline forms are not excluded., The chemical bases for use in this invention for pretreating tobacco are bases which do not significantly react with the tobacco components under

I'

ambient conditions. Chemical bases which do significantly react with the tobacco components under ambient conditions may initiate base catalyzed chemistry in the tobacco, blackening the tobacco and otherwise adversely affecting its smoking characteristics.

Rather, the preferred base is one which is effective in increasing the amount of extracted nicotine without excessively increasing the extraction of flavor constituents. Such a base may react with the components in the tobacco under the conditions of the extraction process. In this way, nicotine is liberated from its salts and immediately taken up in the extraction solvent before other base induced chemistry is initiated within the tobaQco. Since the solubility of 15 the nicotine free base is higher than that of the nicotine salts in the extraction sclvent, one may carry out the extraction process under milder conditions. In this way the quality of the subjective smoking characteristics is preserved. Chemical bases 20 which do not significantly react under ambient conditions but are activated under the conditions of the extraction process include ammonium bicarbonate, sodium or potassium carbonate or bicarbonate, glyco- 'tW 9sylamines, N-glycosides of aldoses, N-glycosides of ketos es and the like.

Other chemical bases ?,re useful in practicing this invention, including ammonia, aqueous ammonia, trimethyl amine and triethyl amine, which can be effective in increasing the amount of extractable nicotine under the extraction conditions, although some such compounds in some concentrations may adversely affect the subjective characteristics of the tobacco. In general, bases which liberate nicotine from its acid salts are effective in practicing ttis invention, especially bases with a pKa greater than about 7.2 and less than about 10. Cornmbinations of suitable bases are also witZinf the scope of the invention.

A glycosylamine useful in the present invention is illustrated by the following formula;

H

100 HO-C-H1

R

where R is a hydrogen, methyl or rethylol substituent.

Illustrative of the inventir~n glycosylamine 20 compounds is l-amino-l-deoxyglucose (RCH OHI), other glycosylamine compounds i--lude 1-amxn,no--deoxymannose (mannosylarnine), l-amino-l-deoxyribooe (ribosylamine), l1-amino-l-deoxygalactose (galactosy4mrine), I-amino-i- Of.1 25 deoxyrhamnose (rhamnosylamnine), l-at(ino-l-deoxyfucose (fucosylamine), l-aMino-l-deoXyXylose (xylosylamine), l-amino-l-deoxyarabinose (arabinosylamine), I-amino-l- 0.99.:deoxylyxose (lyxosylamine), and the like.

The glycosylamine compounds included in 30 this invention are, in pure form, stable and odorless 309* compounds at ambient temperatures. Io addition, the glycosylamine compounds decompose at a relatively low pyrolysis temperature (e4g., 200*-300'C.) to releat.e ammonia, pyrazine and related compounds.

Ammonia-derived glyoogylarnines With an.

unsubstituted amino-group (-H2 are more s-table than glycos'ylamines in which the amino group is substituted. (-NliR or qR 2 if the amino group is an, amino acid structure, then there is a Self-catalyzed Amadori Rearrangement, a conversion of N-glycoside of aldose sugar to an amine derivative ~fthe corresponding ketose, in 'addition to other side-reactions which occur at room temperature.

Mnother preferred form of the invention includes pre.tteating tobacco by spraying it with an aqueous solution of ammonium bicarbonate. Ammonium bicarbonate is useful if applied at about of the dry weight of tobacco (mass/mass) and can be applied at uip to 3% of the dry weight of tobacco. The resulting tobacco, after extraction, is generally less harsh than non-pretreated tobacco, Neutraligation of nicotine salts may also be **:*.carried out by contomporaneously adding a source, of 9...base during the supercritical extraction such that s9 s soo a neutralifation and eXtraction of nicotine occur simulo* 0' 15 taneously and no significant base-induced chemistry 99** 9.aed within the tobacco is inititd so Igo IIn typical exam~ple of 'the pz'ocess of this inventj.Qn, anai-containing trap is prepared by impregn~ating q~ aqueous solution of an acid such as ronopotassiu citric acid into a support such as expanded tobacco stems. The entrapment material is .*so then placed in an etra,;tion Vesaell a, porizus plate placed on top of' the acid-Containinq; trap material and the tobacco to be extraoted iso opo 2$ the plate, The vessel is charged 1i e1nt O, the :pressure is brought to 26 atmosphere& Atd the 0.so temperature is brought to! '70 C The tobacco +o be extract.ed isq a~d uted- to contain an oven volatile content of about The percentage of oven volati4.es in the tobacco is a measure of the moisture content plus a minor fraction of other components and ig determined as follows: %OV wegh lo~o ampl tftor Ca 1 Q t, weight, o~ 3 rao The tobacco in then traw..4ra with ani extraction solvent such ars carbon, fAw~e in the i -i i.

Si I .aa.

i .4 a sa supercritical state, and nicotine and other components are dissolved in the extraction solvent. The enriched supercritical solvent is then passed through the acid containing trap wherein the solvent is freed of nicotine. The supercritical solvent, depleted of nicotine and enriched in other components, is then recycled to the tobacco. The aroma-generating components are extracted from the tobacco only during the initial stages of the cycle since the solvent rapidly becomes saturated with these components, Because nicotine is continuously removed from the solvent, upon recycling the solvent is able to extract additional amounts of nicotine from the tobacco.

The p-,ess isc carried out until the desired level of nicotine reduction in the tobacco is achieved.

Usually 30 to 60 minutes is sufficient. An advantage of this process is that principally the nicotine is removed from the supercritical solvent and the aromagenerating components are substantially preserved.

20 Valve and instrumentation hardware may be arranged to allow by-pass of the CO 2 flow to all vessels, CO 2 flow from an extraction vessel to any entrapment vessel, CO 2 flow both upflow and downflow in any vessel, faster turn-around time, use of both lar'e and small CC fill pumps and pressure drop instrumentation ior up and down flow differential pressure measurement in the entrapment vessels, The flow of CO 2 is in the opposite direction from the force of gravity in the upflow mode and in the same direction in the downflow mode.

For better retention of tobacco subjective smoking characteristics, the extraction vessel may be by-passed during the CO 2 fill and heat period, ad the CO 2 flow directed only through the ent apment vessels. Once extraction process conditions are reached, the COz f!.ow is then directed through the extraction vessel or vessels. Extraction process a 4 9 4*9* aF uL u i,,,lt enlon enttlea: "PROCESS FOR REMOVAL OF BASIC MATERIALS" The following statement is a full description of this invention, including the best method of performing it known to me:-' SNote: The description is to be typed in double spacing, pica type face, in an area not exceeding 250 mm in depth and 160 mm in width, on tough white paper of good quality and it is to be inserted inside this form.

If ;4conditions are reached quickly (4-8 minutes). In an experiment using this process, the beginning of each extraction run was counted when process conditions were reached (temperature, pressure) and the end of each run was counted when the required amount of

CO

2 mass mass of extraction solvent/mass of tobacco) had traversed the tobacco.

Table 1 illustrates the results of extraction runs carried out using carbon as an adsorbent support.

Full flavor American blend tobacco at OV (oven volatiles) was extracted over a period of ,30 minutes using activated carbon as an adsorbent (Run-16, Table The nicotine content of the 15 tobacco was reduced 97.2%, Tobacco flavor was improved, as judged by subjective tests, in comparison to tobacco subjected to longer extraction periods.

When activated carbon saturated with potassium citrate was used as the adsorbent support, the 20 carbon to tobacco ratio was significantly reduced, from 2:1 for carbon alone, to 0.25:1, The level of nicotine extracted was slightly lower due to breakthrough of nicotine through the entrapment columns.

The tobacco subjectives (aroma, flavor and other smoking characteristics) were very poor (Runs-17,-18, Table 1).

In an attempt to extract subjectives only, tobacco, without being premoistened, was extracted with supercritical C02 under control conditions (260 atmospheres, 70 0 C, 12% OV, 30 min, 150 Contrary to the published patent literature (United States Patent No. 4,153,063, Roselius), 94.4% of the nicotine was removed from the tobacco (Run-21, Table 1).

't Table 2 illustrates the results from extraction runs carried out using rpotassium-citrate treated stems as the adsorbent support.

i using organic solvents with and without neutralization of the nicotine salt. Representative of such pro- The best subje~tives overall in the experiments summarized in Table 2 were obtained when shredded stemns were used as the adsorbent support at a stem to tobarcco ratio of about 1:1 by! weight and a potassium citrate to nicotine molar ratio of 8:1 (Run-41, Table The entrapment material was divided equally between two entrapment columns. Subjective quality approached that of the unextracted control and 93.7% of the nicotLine was removed from the tobacco. A one hour extraction period was used at a lower CO 2 flow rate in order to minimize compaction of the stems in the entrapment columns.

Table 2 also shows the following results: Use of dual entrapment columns gives higher levals of nicotine removal than use of a single entrapment column containing the same amount of entrapment material.

An entrapment time split of 15 and 45 minutes or 20 and 40 minutes, in entrapment vessels 2 and 3, respectively, is preferred over a time split of and 30 minutes (based on nicotine breakthrough profiles).

A high stems to tobacco ratio, in excess of about 2:1 gives a "stemmy" character to 0 a the extracted tobacco.

25 Predcying of the stems to maximize potassium *eta citrate loading results in a toasted note. Use of *~:stems, without predrying, gives a more acceptable product, maximum nicotine removal from full flavor tobacco requires a high potassium citrate level on the stems, a low level of background nicotine in the adsorbent support, and use of dual. entrapment columns.

Shredded stems are the przeferred stem type for an adsorbent support. use of izu.Lt Ard rolled stems probably results in a pressure drop problemi and~ use of long stems results in pcor nicotine extraction.

also removed along with nicotine in this single step i t -16- Table 3 shows the results from extraction runs using potassium citrate treated full flavor American blend tobacco as the adsorbent support.

Subjectives were judged good but nicotine removal% was low, in the range of 83% to 88% (Table 3) due to the high level of ricotine already present on the adsorbent support. Higher nicotine removal levels probably require significantly higher potassium citrate loading.

High levels of full flavor tobacco subjectives were present in the CO 2 at the end of the extraction as evidenced by the waxy coating on the go metal surfaces of the extraction/entapment vessels.

*fee Table 4 shows the results from extraction 15 runs using non-tobacco adsorbent supports.

When potassium citrate treated pure 100% cotton fabric was used to remove nicotine from tobacco, subjectives were judged not as good, thin with slight mouthcoating, as with potassium citrate treated stems 20 (Run-27, Table 4).

Use of potassium citrate treated pure alphacellulose gave a low removal of nicotine from tobacco, 0* 9 probably due to the non-uniform distribution of potassium citrate on the cellulose support. Subjectives were judged unacceptable, bittergreen, dry, and astringent (Run-32, Table 4).

Use of cocoa shells as an adsorbent support gave a nicotine removal of 96.9% using a single entrapment column. Subjectives were characterized as acceptable, tobacco like, slightly burnt and sweet with no mouthcoating (Run-30, Table 4).

Use of cocoa shells as the adsorbent support also permits the transfer of desirable flavor attributes from one natural substrate (cocoa shells) to another (tobacco). One may also transfer the desirable flavor subjectives from Burley tobacco to an expanded stem support.

preserving aroma-producing components.

Preferably the moisture content of the tobacco is up to 30% by weight.

7 Table 5 illustrates the results from extraction runs carried out using unwashed coarse shredded stems, unwashed fine shredded stems and washed fine shredded stems as the adsorbent support.

Combinations of stem type and shredded stem particle size were tested for extraction efficiency and product quality. Best extraction efficiency was obtained with washed fine shredded Bright stems.

Table 6 illustrates the results of a number of extraction runs carried out using washed fine S shredded Bright stems.

Extraction of more than 96% of nicotine was achieved yet the product was subjectively rated as average in smoking characteristics.

15 Table 7 illustrates the results from j extraction runs carried out utilizing 2% ammonium bicarbonate pretreatment of the tobacco filler.

The following variables were tested: Solvent to tobacco ratio was reduced from 20 150 to 113 m/m, extraction time was shortened from 60 min to 45 min., and the temperature of the extraction process was lowered from 700 to 55 0 C. Subjec- S tives were judged very good and nicotine extraction w's high, over 96%.

Extraction of 2% ammonium bicarbonatepretreated tobacco at 70 0 C, 75 m/m and for 30 minutes gave 95.2% nicotine removal (Run 51, Table However, subjectives were judged not as good compared to product obtained at lower extraction temperatures.

Further reduction in extraction time minutes), and further reduction of the solvent to tobacco ratio (75 m/m) at 55°C gave reduced extraction efficiency, 94% nicotine removal (Run 57, Table Table 8 illustrates the results from extraction runs carried out using a single vessel design in the upflow and downflow modes.

In the upflow mode, the flow of carbon dioxide is in the opposi te direction as the force of gravity and in the downflow mode, the flow of carbon dioxide is in the same direction as the force of gravity. The incipient fluidization velocity is about 1.1 cm/sec and the pressure drop does not become significant until up to about 1.6 cm/sec. The tobacco extraction data obtained at about 0.9 cm/sec, upflow, compared favorably with the downflow control (Run 41B vs. Run 49B, Table 8).

Table 8 alrso illustrates the relationship between in/in and extraction time.

The importance of the solvent to tobacco ratio was established in two experiments by varying the extraction time (from 30 min to 75 min) at a .'fixed in/in. The results show that a minimum~ solvent to tobacco ratio is needed (about 113 in/in) to achieve i~ excess of 96% extraction of nicotine. The time of extraction is not considered important within the 20 range tested (Run 45-30 min,; Run 66-45 min.; Run 67-75 mmn.).

9 wthout Tobacco materials in solution in CO 2 witoutnicotine, were collected in two runs from full flavor American blend filler (Runs 42, 43, Table The tobacco was pretreated with potassium citrate to convert nicotine to its salt. The tobacco solubles were extracted with supercritical CO 2 at 260 atmospheres and 551C.

The process disclosed was also used to deposit tobacco materials in solution in CO 2 1 obtained from the dry ice expanded tobacco process, as disclosed in United states patents Re 32,013 and 32,014 onto the tobacco filler (Run 45, Table 8).

Extensive CO 2 sampling during the extraction runs showed that nicotine concentration in CO 2 follows a first order rate of extraction.

c Il I r rrr I i~ll

I'

-9- Tables General Notes All runs were carried out at about 260 atmospheres, 70 0 C, 25% OV (oven volatiles).

Subjective rating was based on a value of "zero" for unextracted full flavor American blend tobacco. A positive value indicates an improved rating.

All runs were carried out without extraction during the heat-up via bypass of the entrapment vessels during the fill and heat-up period.

The oven volatiles o. the tobacco filler 4.

in the extraction vessel decreased when the oven .volatiles of the stems were 25% and 35%. when the oven volatiles of the stems were 45% and 55%, the 15 results were inconclusive.

•Pre-drying of stems before potassium citrate treatment was not done for the following Runs 26, 28, 29, 31, 35 thru 39, 41 thru 47) As O S

*Q

The ability to use less solvent also results in less 'I

U-

fl KEY TO 'THE TABLES

AB

ALPHA

CARBON

COCOA

I0 10 4 0a I ft 00 k

COT

CRS

ETOH

FF

KC

2% ammonium bicarbonate alpha cellulose activated carbon cocoa shells with fines removed via screening cotton cut and rolled stems ethyl alcohol full flavor American blend tobacco filler mono-potassium citrate (+n.mKC n.m moles sprayed onto the entrapment support) long stems low tar blend tobacco mass of carbon dioxide/mass of tobacco propylene glycol shredded stems strip blend tobacco unwashed coarse shredded stems unwashed fine shredded stems washed fine shredded stems <1 44«

B'

4 '0 0. 0.~ 4. 0 .0

B

&O0@4B 0 04 .4 04 0 60

LS

LTAR

M/M

PG

SS

STP

20 UCSS

UFSS

WFSS

I

I *aa. a .5

Q

o r a. a 9 gsa a a a c a- .3 3 3 3 a a r **e t, e a a 3 a a. a' 9 @3 3 ar a ,a TABLE 1 TOBACCO/CARBON RUNS

VESSEL

FILLER IN

EXTRACTION

VESSEL [1] LOADING, KG

ENTRAPMENT

VESSEL

#1 RUN NO.

18

CARBON

(DWB)

ENTRAPMENT

VESSEL

#2 18

CARBON

N/A

z] 2.2 CARBON KC

CO

2

FLOW

M3/HR

NICOTINE

MINS. M/M REMOVAL

SUBJECTIVE

RATING

CONDITIONS

TIME

15/15 150 97.2 150 90.8 9 9 FF 12% OV CARBON KC2 2.2 CARBON KC 18

CARBON

-3.0 En tn o o Fr CD C m o H- 0 CD rt

Z

I1 m ),a 0 0 0 rP F1 (D Q 15/15 15/15 150 94.1 170 94.4 -2.55 18,

CARBON

-2.5 Run no. 21 was carried out with extraction during heatup period, in order to extract subjectives only.

1. FF: Full flavor American blend upless noted otherwise.

2. CARBON KC: Activated carbon saturated with monopotassium citrate.

S. S S S a S.

S S S S S TABLE 2 TOBACCO/TREATED STEM RUNS

VESSEL

FILLER IN

EXTRACTION

VESSEL [11 RUN NO- 2-25 LOADING, KG ENTRAPMfENT

VESSEL

SSI7_ 8 SS+7_2 8 SSI-3 .6KC 4 -SS+3.6KC 8 SS+13_3KC SS+13.3KC 4 SS+3. 6KC

(DWB)

ENTRAPMIENT

VESSEL

8 SS+7-2KC

N/A

P/A

8 SS+13_3KC 4 SS+3_6KC CO 2FLOW M 3/HR CONDITI ONS TIMlE iIINS. il/M

NICOTINE

REMOVAL

30/30 150 90_Ac 88.3 91.4 (Breakthrough) -2.25 SUBJEC71VE RP-7NG

I

78.9 30/50 210 30/30 150 95-0 96.6 89.8 -2.25 [11 1FF: Full flavor american blend unless noted otherwise.

Production runs f ,r machine made cigarette quality evaluation.

22 k

I-

a a Vr V V Va a *t S V. V V V a -SV V S 0 0 V 0 5 TABLE 2 (continued) TOBACCOITREATED STEM RUNS VESSEL LOADING, KG (DWB) FILLER IDN ENTRAPMENT' ENTRAPMENT EXTRACTION VESSEL E TSEL VESSEL if 1_4012

CONDITIONS

TIME

RUN NO0 i 9 SS+3-6KC 4 -4KC 4 5+7.2KC 4 SS+3-.6KC 8 SS+13-3KC 4 SS+3,6KC 4 SS3.6KC 8 SS+3,6KC 4 SS+5 4KC 4 SS+7.2KC 4 SS+3 -6KC 8 SS+13-3KC 4 SS+3 6KC 4 SS+3.,6KC CO 2FLOW 1,8 3.6 1-8 1-8

MINS-

20/40 20/40 10/20 20/40 20/40 20140 20/40 94.3

NICOTINE

/l REMOVAL 150 92-2 150 89.1 150 93-9 150 94-5 150 82-5 150 94.7

SUBJECTIVE

RATING

-1.33 -0.75 -0-5 -1.75 -0.33 -0.9 p- Hi-

H-

H- 0 ct

OF-I

rt II FlI F1 (D CD 0) nr~ DPi H- rt I r- 0 rt rt 0 131 rt e) (D O rt i- D o i 0 o U)

(D

o cn 0 o Hj 0

(D

rt Un 0

(D

ti 9

STP*

9 LTAR7* r I i r r 4 I C O;

S

S S S S 'TABLE 2 (continued) TOBACCO/TREATED STEM RUNS RUN NO-

TESSEL

FILLER 11I

EXTRACTION

VESSEL

9k-' EF OV LOADING, KG

ENTRAPMENT

VESSEL

#1

(DWB)

ENTRAPMENT

VESSEL

-#2 C2 FLOW M3 /HR

CONDITIONS

TIME

NICOTINE

M/M REMOVAL

SUBJECTIVE

RATING

SS+3.6KC 4 SS-3-6KC 4 SS--3 6C 4 SS+3-6KC SS+,3 -6K 4 SS+-i-6KC 4 SS+3 -6KC 4 SS-3.6KC 4 S'3+3--.6KC 4 S+3 6KC 4 SS± ,6KC 4 SS3 6KC 15/45 150 92.7 -0.50 15/45 15/45 15/A5 92-8 90-4 -1.25 93-7 91.8 +0.25 -0.25 4 )S+3,6KC 4 SS+3 AKC 15/45 15/45 150 90.8 150 89.6 -0.75 l-O: a ar a a *L a S. a *0 0 4 ao a a. S a a a a a* a a a a a S S 0r S r a.

TABLE 2 (continued) TOBACCO!TREATED STEM RUNS VESSEL LOADING, KG RUN NO,.

FILLER IN

EXTRACTION

VESSEL

4 SS+3-6KC

ENTRAPMENT

VESSEL

#I

(DWB)

ENTRAPBENT

VESSEL

2

CO

2

FLOW

m 3 /HR

NICOTINE

REMOVAL

SUBJECTIVE

RATING

CONDITIONS

'TIME

MINS-

78-8 94-7 L.S-36KC Is

CAMN

8 LS+7.2KC i4 LS+3-6(C 4-5

FF

20140 150 15/45 150 -1.75 82-0 2y 0

(D

'I

D

a I-

(D

CD

0 r

(D

0

Z

n r- -o 0 11

C-

0D 4 CRS+3 6KC 30/30 64.8 Fodwztion rtz=F xrib-hZ.e m~ad2e ciJrette quality evaluation- -4 9 S 95 C S S. S S 5. 5.9 S

S

S S

S

SES S S S 55 5 S S S S S S S S S C 55 S S S S 9.5 5 TABLE 3 TOBACCO RUNS RUN NO.-

VESSEL

FILLER IN

EXTRACTION

VESSEL

FF

LOADING, KG

ENTRAPMIENT

VESSEL

7_8 FF+ 6..3XC

(DWB)

ENTRAPMENT

VESSEL

#2

CONDITIONS

CO2 FLOW TIMlE 11 3/HR

N'ICOINE

INS- 1111RIOA

SUBJECTIVE

RATING

1-8 83.4

FF

8 FF+7.2KC 8 FFI-7.2KC 1.8 30140 300 88.8 NOTE:_ Pressure drop problems in the adsorber resulted in slower CO flow rate- I 02 ~1 I; S 54

S

De .0.CC a *5 C S C C S C *j C -a C 4 5 S C *s C 4r TAMIE 4 TOBACCO/TRTED NON-TOBACCO MATRIX RUNS

VESSEL

FILLER IN

EX;TRACTON

VESSEL RUN NO.

LOADING, KG ENTRA'1ENT

VESSEL

#1 9 COT+13,3KC COT+13_3KC

N/A

(DWB)

ENTRAPIEN

VESSEL

9 COT+13-3KG 7.5 COT+13 .3KC

CONDI[TIONS

C0 FLOW TIME M3 /JUi MINS- N/M

NICOTINE

REMOVAL

SUBJECTIVE

RATING

30/30 20/40 150 92.8 150 91.1 -0.75

FE

ALPHA

+7.2KC

FE

COCOA

+7.2KC

FF

COCOA

6KC N/A 79.8 96.9 93.1 N/A -0.6 311 ICC~ a ~r r, r b C. Ca *Sa

C

CC. S C SC C C C CCC

I

TABLE SHREDDED STEMS RUNS VESSEL LOADING, KG (DWB) EXTRAC-ION ENTRAPMENT ENTRAPMENT VESSEL VESSEL 1 VESSEL 2 RUN NO.

TIME, MIN.

ENT /ENT 30/30

CONDITIONS

CO FLOW

KZ/MIN

0 TO 30 TEMP 1HICO. SUBJ.

M/M °C REMOVAL RATING 70 9 FF 9 FF 9 FF 6 FF 6 FF 9 FF 9 FF 4 UCSS +3.6 KC 3 UFSS +2-7 KC 1 WFSS +0.9 KC 4 UFSS 4 UFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 UCSS +3.6 KC 3 UFSS +2.7 KC 1 WFSS +0.9 KC 4 UFSS 4 UFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6KC 15!45 15/45 15/45 15/45 8/22 8/22 22.5 22-5 22.5 22.5 22.5 22.5 70 94 70 93 70 92 70 93 -0.8 -0.4 -0.7 +0.4 9 FF+AB 9 FF+AB 75 70 95 75 55 94 NOTES: 1. RUN 03: DOWNFLOW IN ENTRAPMENT VESSEL 1, UPFLOW IN ENTRAPMENT VESSEL 2.

2, M/M IS FOR EXTRACTION CONDITIONS ONLY EXTRACTION VESSEL FILL AND HEATUP ARE NOT INCLUDED.

28

I

~T I- i i. ii a C C CS S S S~ S S: S S 5* S S S C C S S e -S S_ RUN NO.

03 07 08 09 11 12 13 14 VESSEL LOADING, KG (DWB) EXTRACTION ENTRAPMENT ENTRAPMENT VESSEL VESSEL I VESSEL 2 9 FF 4 WESS 4 WFSS +3.6 KC +3.6 KC 9 FE 4 WFSS 4 WFSS +3.6 KC +3.6 KC 9 FF 4 WESS 4 WFSS +3.6 XC +3.6 KG 9 FF 4 WFSS 4 WFS +3.6 KC +3.6 KC 9 FF 4 WFSS 4 WESS +3.6 KC +3.6 KG 9 FF 4 WFSS 4 WFSS +3.6 KG +3.6 KC 9 FF 4 WFSS 4 WFSS +3.6 KC +3.6 KC 9 FF 4 WFSS 4 WESS +3_6 KC +3.6 KC

WASHED

TIME, MIN.

ENT /ENT 1 2 15/45 1145 15/45 15/45 15/45 15/45 15/45 15/,45 e S S S ee S S* C C S* t C S *C :be TABLE 6 FINE SHREDDED ST

CONDITIONS

CO FLOW KG/MIN M/ 22.5 15 22.5 15 22.5 15 22.5 15 22.5 15 22.5 15 22.5 15 22.5 15 EMS RUNS

TEMP

i OC 0 70 0 70

NICO.

REMOVAL

95 97 97 95 97 96 97 96

SUBJ.

RATING

-0.8 -0.8 -0.2 -0.6 -0.4 -0.8 0 70 AVERAGF 96 a a ta aa *r at a ar a a a* ae a. a a a at a a.

TABLE 7 AMMONIUM BICARBONATE RUNS a VESSEL LOADING, KG (DWB) CONDITIONS

EXTRACTION

RUN NO. VESSEL

FF+AB

ENTRAPMENT

VESSEL 1 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS

KC

4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC

ENTRAPMENT

VESSEL 2 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC TIME, MIN.

ENT /ENT 15/45 15/45 15/45 15/45 15/45 15/45 15/45 15/45 15/45 15/45 11/34 CO FLOW K6/MIN 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 TEMP NICO.

M/M oC REMOVAL 150 55 97 150 55 97 150 55 97 150 55 97 150 55 97 150 55 97 150 55 97 150 55 96 150 55 98 150 55 97 113 55 97

SUBJ.

RATING

-0.1 +0.4 +0.3 +0.2 +0.4 +0.7 +0.3 TABLE 7 (CONTINUED) ATMONIUN BICARBONATE RUNS VESSEL LOADING, KG (DWB)

EXTRACTION

RUN NO. VESSEL

FF+AB

ENTRAPMENT

VESSEL 1 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KG 4 WFSS +3.6 KC 4 WFSS +3.6 XC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WESS +3.6 )CK

ENTRAPMENT

VESSEL 2 4 WFSS +3.6 XC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WESS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC 4 WFSS +3.6 KC TIME, MIN.

ENT /ENT 2 11/34 11/34 11/34 11/34 11/34 11/34 11/34 11/34 11/34 11/34 11/34 31

CONDITIONS

CO FLOW

KG/MIN

22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 22.5 M/n 113 113 113 113 113 113 113 113 113 113 113 TEMP NICO.

oC REMOVAL 55 97 55 95 55 96 55 96 55 96 55 97 55 97 55 97 55 98 55 97 55 96

SUBJ.

RATING

+0.6 +0.7 +0.7 +0.4 +0.4 +0.4 I I I I a a a a a a S a *a a..

a a a a a a a a a a a a a a a a a.

a a *a TABLE 7 (CONTINUED) AM4MONIUMI BICARBONATE RUNS VESSEL LOADING, KG (DWB)

EXTRACTION

RUN NO. VESSEL

ENTRAPMIENT

VESSEL I

ENTRAPMIENT

VESSEL 2_ TIME, MIY-.

ENT./ENT,,

CONDITIONS

CO FLOW K~/MIi TEMP NICO. SUBJ.

hM/ 0 C REMOVAL RATING 9 FF+AB 19 FF+AB 9 FF+AB 4 WFSS +3.6 KC 4 WFSS' +3.6 KC 4 WESS i-3_6 KC 4 WFSS +3_6 KC 4 WES S 6 KC 4 WESS 6 KC 11134 11/34 19/56 22-5 22.5 13.5 55 97 55 97 55 97 AVERAGE 97 +0.4 +0.4 i a S.

S

S S S S S S S *5 S S a S 5.5 *SS

*SS

S S a.

a

S

TABLE 8 EXPERIMENTAL RUNS FLAVOR ADDBACK: VESSEL LOADING, KG (DWB) EXTRACTION ENTRAPMENT ENTRAPMENT VESSEL VESSEL 1 VESSEL 2 RUN NO.

TIME, IN.

ENT

1

/ENT

2 8/22

CONDITIONS

CO FLOW K6/MIN TEMP %4 NICO. SUBJ.

11/I 0 C REMOVAL RATING 9 FF+.AB 4 WFSS 6 KC

+FLAVOR

4 WFSS 6 KC tFLAVOR 113 SOLUBLES COLLECTION: VESSEL LOADING, KG (DWB) EXTRACTION ENTRAPMENT ENTRAPMENT VESSEL VESSEL I VESSEL 2 RUN NO.

9 FF +7.2 KG 9 FF +7.2 KC 12 FF 6 KG 12 F +9.6 KG 12 FF +i9.6 KC 12 F +9.6 KG TIME, MIN.

ENT,,/ENT 2 3-5 HIRS 1. 8 IIRS

CONDITIONS

CO FLOW K6/11IN

TEMP

0

C

SOLVENT

22.5 22.5 55 PG 55 ETOH p .0 be be* 0 See a a *5 0 a Oa a. a.

S

.0 .a 00 a e S* 1. 1. a.1 a a, S S TABLE 8 (CONTINUED) EXPERIMENTAL RUNS SINGLE VESSEL DESIGN: DOWNFLOW AND UPFLOW VESSEL LOADING. KG (DWB) CONDITIONS

EXTRACTION

RUN NO. VESSEL

ENTRAPMENT

VESSEL 1

ENTRAPMENT

VESSEL 2 TIME, MIN.

ENT /ENT i 32 CO F0OW VELOCITY KG/Mn_ CM/SEC TEMP NICO.

M/M oC REMOVAL

SUBJ.

RATING

3.4 FF+AB +3 WFSS +2.7 KC 0.9 DOWN 106 55 86

FF+AB

+4 WFSS +3.6 KC 0.9 DOWN 157 55 96 +0.1 0 FF+AB +4 WFSS +3.6 XC 14 0.9 DOWN 180 55 96 14 0.9 DOWN 125 55 93 3.,4 FF+AB +3 WFSS +2.7 XC

FF+AB

+4 WFSS +3.6 KC 14 0. 9 UP 157 55 97

FF+AB

+4 WFSS +3.6 KC 1.3 UP 157 55 94 THEREFORE THE M/M REPORTED NOTE: 1. TOBACCO FILLER AND SHREDDED ITEMS WERE IN THE SAME VESSEL IN RUNS l1 AND 49.

FOR RUNS 41 AND 49 INCLUDES THE NASS OF CO2 DURING THE FILL AND HEATUP PERIOD.

34

YI

-i r The following examples are illustrative.

Example 1 Each of the entrapment vessels 2 and 3 in Figure 1 was loaded with 2.2 kg of cotton cloth which were impregnated with 2 liters of an aqueous solution containing 920.8g monopotassium citrate. 12 Kg of full flavor American blend cigarette filler tobacco OV) was placed in extraction vessel 1.

With the valves to the entrapment vessels 10 closed, the supercritical CO 2 was brought to 70 0 C and i *260 bai. Then the valve to the first trap was opened and the stream of supercritical CO 2 was circulated through the extractor and the first trap for S* minutes. At the end of this time, the valve to the second trap was opened and the valve to the first trap was closed. The flow of supercritical CO 2 was circulated to the second trap for an additional period of 15 min. At the completion of 30 minutes total extraction time, the circulation was stopped and the CO 2 was removed from the system. Tobacco t blend and entrapment materials were removed from the system and submitted for nicotine analysis. A reduction in nicotine content of the tobacco blend of 77.4% was obtained. The tobacco blend retained a 25 strong characteristic aroma which was not different from the unextracted blend.

Upon smoking, similar tobacco impact was obtained compared with unextracted tobacco.

Example 2 4.4 Kg of expanded bright tobacco stems were impregnated with 1.78 1 of aqueous monopotassium citrate to yield a moistened stem support containing 409.8g of monopotassiu, citrate. This entrapment support was placed in the bottom portion of extraction vessel 1. A porous plate was placed on top of the i entrapment material and 3.52 kg of burley tobacco (2 OV) was loaded into the extractor vessel. The entrapment vessels 2 and 3 in Figure 1 were removed from the flow system by valve adjustment. A stream of supercritical CO 2 was circulated through the extractor with the temperature and pressure brought to 70C and 260 atmospheres, respectively. After minutes extraction time, the circulation was stopped and the CO 2 was removed from the system.

-3 6- Tobacco product (burley) and entrapment material (2 t 0V) was loaded intr the extractor vessel. The (expanded stems) were removed and submitted for nicotine analysis. The burley tobacc product had a reduction in nicotine content of 92.4%. Analysis of Sthe expanded stem entrapment material yielded a corresponding increase in nicotine content. The burley tobacco product retained a strong characteristic aroma which was not different subjectively from the unextracted burley tobacco.

Stin..Upon smoking the extracted burley tobacco, 20 similar tobacco impact was obtained compared with the tobacco impact from unextracted tobacco.

S 9 *4 k e

Claims

1. A method for the selective removal of at least one basic component from a solvent in an extraction process, wherein said basic component is extracted from a material together with a plurality of other substances by a solvent at a high pressure, said solvent being in a physical state which is either a liquid at a pressure of 50 to 300 atmospheres or a supercritical fluid at a temperature from the critical temperature of the solvent to 120°C an a pressure of 70 to 0 to 1500 atmospheres, said component being removed from the extraction solvent by contacting said solvent directly following the extraction of said material and in the same physical state, with a non-volatile acid which is not soluble in the solvent and which selectively removes the basic component without removing the other substances contained in the same solvent. i 2, A method according to claim 1 wherein the acid is a polycarboxylic acid or a monovalent salt thereof, 3, The method according to claim 1 or 2 wherein the extraction solvent comprises carbon dioxide, argon, SF6, NaQ, lower halogenated hydrocarbon or lower hydrocarbor. S4. The method according to claim 1, 2 or 3 wherein the non-volatile acid is dissolved or suspended in water, acid, aqueous acid or aqueous salt solution,

4. S

5. The method according to any one of the preceding claims wherein the acid is contained on a support medium. 6, The method according to claim 5 wherein the support medium is cotton cloth, tobacco stem, carbon, cellulose or tobacco filler, 37 -IT -IT I 1"

7. The method according to any one wherein the solvent is recycled from extraction stage, of the preceding contact with the claims acid to the 0606 6* 0* 0 *00* 9 *0*S 0 0 0* @0 0* 0 0@

8. The method according to any one of the preceding claims wherein the basic component is nicotine.

9. The method according to claim 0 wherein the nicotine is derived from tobacco by extraction with a normally gaseous solvent in the presence ol at least 10% by weight of moisture, based on the weight of the tobacco, and wherein nicotine is selectively removed from the solvent by the non-volatile acid while preserving aroma-producing components,

10. The method according to claim 9 wherein the moisture content of the tobacco Is up to 30% by weight, I1. The method according to any one of th4 preceding claims wherein the non-volatila acid is monopotassium citrate. 12, The method according to any one of the preceding claims wherein the basic component is derived from a plant product containing a plurality of substances including acid salt forms of said basic component, and wherein said plant product is first contacted with a chemical base which does not substantially react under ambient conditions with the acid salt forms of said basic component or with other plant components but can reac't with the said acid salts under the conditions of an extraction process, and the plant product is then contactod with said extraction solvent, in the supercritical or liquid state, under conditions such that the chemical base does react with the acid forms of the basic component in the plant product, prior to contacting said solvent with said non-volatile acid. 13, The method accord'ng to claim 12 wherein the chemical base has a pKo greater than 7.2 and less than

14. The method according to claim 12 or 13 wherein the chemical 6 oeo0 oo 0 *000 oeoS 0**0e 38 base is ammonium bicarbonate, a glycosylamine, an N-glycoside of an aldose or an N-glycoside of a ketose. The method according to claim 12 or 13 wherein the chemical base is sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonia aqueous ammonia, triethylamine or trimethylamine. 16, A method for the selective removal of at least one basic component from a plant product containing a plurality of substances including acid salt forms of said basic component, wherein said plant product is first contacted with a chemical base which does not substantially react under ambient conditions with the acid salt forms of said basic component or with other plant components but can react with the said acid salts under the conditions of an extraction process, and the plant product is then contacted with an extraction solvent in a physical state which is either a liquid at a pressure of 50 to 300 atmospheres or a supsrcritical fluid at a temperature from the critical temperature of the solvent to 1200C and a pressure of 70 to 1500 atmospheres, the conditions being such that the chemical base does rviact with the acid salt forms of the basic component in the plant produco.

17. The method according to claim 16 wherein the chemical bate has a pK. greater than 7,2 and less than

18. The method according to claim 16 or 17 wherein the chemical base is ammonium bicarbonate, a glycosylamine, an N-glycoside of an aldose or an N-glycoside of a ketose,

19. The method according to claim 16 or 17 wherein the chemical base is sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonia, aqueous ammonia, triethylamine or trimethylamine, The method according to any of claims 16 to 19 coin the extraction solvent is carbon dioxide, argon, $Fa, N0, lower -39 4 halogenated hydrocarbon or lower hydrocarbon.

21. The method =cording to any of claims 16 to 20 wherein the basic component in the plant product is nicotine.

22. The method according to any of claims 16 to 20 for the selective extraction of nicotine from tobacco while .reserving aroma-producing components, wherein the chemical base does not significantly react with acid salts of nicotine under ambient conditions bu' does react with the nicotine salts under the extraction conditions, and whtrein the tobacco is extracted with a normally gaseous solvent in the presence ot at least 10% by weight of moisture based on the weight of the tobacco, said solvent being in the physical state as defined. S 'V 6 6*9* q. b 9. S I 9 .9 ii 9 S f.d

23. The method according to content of the tobacco is up D AT ED1 thkis 1 9th claim 22 wherein the moisture to 30% by weight, Vty of2 April, 1991. PILIP MORRIS PRODUCTS INC, By their Patent Attorneys: CALINAN L2AWRIE &SSSOS S 995& a.

94.. 9.99 I. S 96* S A V 9 419 9 AAS~