OA11240A - Method of treating tobacco to reduce nitrosamine content and products produced thereby - Google Patents

Abstract

Methods of reducing the content of and preventing formation of carcinogenic nitrosamines in harvested leafy plants such as tobacco and marijuana are disclosed. The methods are directed to subjecting the plant to microwave and/or higher frequency radiation, at appropriate times in the cure cycle. With tobacco, products suitable for human consumption, such as cigarettes, cigars, etc., can be made in accordance with the present invention, having contents of tobacco-specific nitrosamines on a par with fresh-cut, green tocacco. In preferred embodiments, the resultant tobacco products are dried, golden-yellow leaves having almost negligible amounts of the known carcinogens NNN and NNK, in comparison to conventionally cured tobacco.

Description

011240

METHOD OF TREATING

TOBACCO TO REDUCE NITROSAMINE CONTENT,AND PRODUCTS FRODUCED THEREBY

Field Of The Invention

The présent invention relates to a method of treating5 tobacco to reduce the content of, or prevent formation of,harmful nitrosamines which are normally found in tobacco. Theprésent invention also relates te tobacco products having lownitrosamine content.

Cross-reference to Related Applications 10

This is application is a continuation-in-part of application

Serial No. 08/879,905 filed June 20, 1997, which is a continuation-in-part of application Serial No. 08/757,104 filed

December 2, 1996, which is a continuation-in-part of application

Serial No. 08/739,942 filed October 30, 1996, now abandoned, 15 which is a continuation-in-part of application Serial No. 08/725,691, filed September 23, 1996, now abandoned, which is a continuation-in-part of Application Serial No. 08/671,718, filed

June 28, 1996. The présent application and the applications

recited above, with the exception of Application Serial No.h U 08/671,718, filed June 28, 1996, claim priority to provisional application Serial No. 60/023,205, filed August 5, 1996.

Sackcround Of The Invention

Others hâve described the use of microwave energy to dry agricultural products. Use of microwave energy to cure tobaccoY b is disclosed in U.S. Patent No. 4,430,806 to Hopkins. In U.S. 011241

Patent No. 4,898,189, Wochnowski teaches the use of micrcwavesto treat green tobacco in order to control moisture content inpréparation for storage or shipping. In U. S. Patent No.3,599,976, microwave energy is described to kill insect infestation of tobacco. Moreover, techniques using imprégnation 5 of tobacco with inert organic liquids (U.S. Patent No. 4-,821,747)for the purposes of extracting expanded organic materials by asluicing means hâve been disclosed wherein the mixture wasexposed to microwave energy. In another embodiment, microwaveenergy is disclosed as the drying mechanism of extruded tobacco- 10 containing material (U.S. Patent No. 4,874,000) . In U.S. PatentNo. 3,773,055, Stungis discloses the use of microwave to dry andexpand cigarettes made with wet tobacco.

Prior attempts to reduce tar and harmful carcinogenic nitrosamines primarily hâve included the use of filters in 15 smoking tobacco. In addition, attempts hâve been made to useadditives to block the effects of harmful carcinogens in tobacco.These efforts hâve failed to reduce the oncologie morbidityassociated with tobacco use. It is known that fresh-cut, greentobacco has virtually no nitrosamine carcinogens. See, e.g., 20

Wiernik et al, "Effect of Air-Curing on the Chemical Composition of Tobacco," Recent Advances in Tobacco Science, Vol. 21, pp. 3 9 et seq., Symposium Proceedings 49th Meeting Tobacco Chemists'

Research Conférence, Sept. 24-27, 1995, Lexington, Kentucky (hereinafter "Wiernik et al"). However, cured tobacco is knowndï b to contam a number of nitrosamines, including the harmfulcarcinogens N'-nitrosonornicotine (NNN) and 4-(N-nitroscmethylamino)-1-(3-pyridyl)-1-butanone (NNK) . It is widely 011240 accepted that such nitrosamines are formed post-harvest, duringthe curing process, as described further herein. Unfortunately,fresh-cut green tobacco is unsuitable for smoking or otherconsumption.

In 1993 and 1994, Burton et al at the University of Kentuckycarried out certain experiments regarding tobacco-specificnitrosamines (TSNA), as reported in the Abstract, "Réduction ofNitrite-Nitrogen and Tobacco N’-Spécifie Nitrosamines In Air-Cured Tobacco By Elevating Drying Températures", Agronomy &Phytopathology Joint Meeting, CORESTA, Oxford 1995. Burton etal reported that drying harvested tobacco leaves for 24 hours at71°C, at varions stages of air curing, including end of yellowing(EOY), EOY+3, EOY+5, etc. resulted in some réduction ofnitrosamine levels. Reference is also made to freeze drying andmicrowaving of certain samples, without detail or results.Applicant has confirmed that in the actual work underlying thisAbstract, carried out by Burton et al at the University ofKentucky, the microwave work was considered unsuccessful.Certain aspects of Burton et al's 1993-94 study are reported inWiernik et al, supra, at pages 54-57, under the heading "ModifiedAir-Curing". The Wiernik et al article postulâtes thatsubjecting tobacco leaf samples, taken at various stages of air-curing, to quick-drying at 70°C for 24 hours, would remove excesswater and reduce the growth of microorganisms; hence, nitrite andtobacco-specific nitrosamine (TSNA) accumulation would beavoided. In Table II at page 56, Wiernik et al includes some of3urton et al's summary data on lamina and midrib nitrite and TSNAcontents in the KY160 and KY171 samples. Data from the freeze- 3 011240 drying and the quick-drying tests are included, but there is nomention of the microwaved samples. The article contains thefollowing conclusion:

It can be concluded from this study that itmay be possible to reduce nitrite levels and ’5 accumulation of TSNA in lamir.a and midrib by applying heat (70°C) to dark tobacco afterloss of cell integrity in the leaf. Drying .the tobacco leaf quickly at this stage of ’curing reduces the microbial activity thatoccurs during slow curing at ambienttempérature. It must be added, however,that such a treatment lowers the quality ofthe tobacco leaf.

Id. at page 56. The Weirnik et al article also discusses 15 traditional curing of Skroniowski tobacco in Poland as an exampleof a 2-step curing procedure. The article States that thetobacco is first air-cured and, when the lamina is yellow orbrownish, the tobacco is heated to 65 °C for two days in order tocure the stem. An analysis of tobacco produced in this mannershowed that both the nitrite and the TSNA values were low, i.e.,less than 10 micrograms per gram and 0.6-2.1 micrograms pergrams, respectively. Weirnik et al theorized that these resultswere explainable due to the rapid heating which does not allowfurther bacterial growth. Weirnik et al also noted, however,that low nitrite and TSNA values, less than 15 micrograms pergram of nitrite and 0.2 microgram per gram of TSNA, were obtainedfor tobacco subjected to air-curing in Poland.

Summary of the Invention

One object of the présent invention is to substantiallyeliminate or reduce the content of nitrosamines in tobaccointended for smoking or consumption by other means. Δ. 011240

Another object of the présent invention is to reduce thecarcinogenic potential of tobacco products, including cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum andlozenges.

Still another object of the présent invention is to5 substantially eliminate or significantly reduce the amount of tobacco-specific nitrosamines, including N'-nitrosonornicotine (NNN), 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK), N' -nitrosoanatabine (NAT) and N'-nitrosoanabasine (NAB), in such tobacco products. 1îj

Another object of the présent invention is te treat uncuredtobacco at an appropriate time post-harvest so as to arrest thecuring process without adversely affecting the tobacco'ssuitability for human consumption.

Another object of the présent invention is to reduce thecontent of tobacco-specific nitrosamines in fully cured tobacco.

Yet another object of the présent invention is to reduce the content of tobacco-specific nitrosamines, particularly NNN and NNK, and métabolites thereof in hutnans who smoke, consume or

otherwise ingest tobacco in sortie form, by providing a tobaccohJ product suitable for human consumption which contains asubstantially reduced quantity of tobacco-specific nitrosamines,thereby lowering the carcinogenic potential of such product.Preferably, the tobacco product is a cigarette, cigar, chewingtobacco or a cobacco-containing gum or lozenge.

The above and other objects and advantages in accordancewith the présent invention can be obtained by a process for 01 1 2 4 C. reducing the amount of or preventir.g formation of nitrosaminesin a harvested tobacco plant, comprising subjecting at least a portion of the plant to microwaveradiation, while said portion is uncured and in a Statesusceptible to having the amount of nitrosamines reduced orformation of nitrosamines arrested, for a sufficient time toreduce the amount of or substantially prevent formation of at least one nitrosamine.

It is preferred that in the process of the invention, thestep of subjecting to microwave radiation is carried out on atobacco leaf or portion thereof after onset of yellowing in theleaf and prior to substantial accumulation of tobacco-specificnitrosamines in the leaf. It is also preferred that in theprocess of the invention, the step cf subjecting to microwaveradiation is carried out prior to substantial loss of the leaf'scellular integrity.

In additional preferred embodiments of the process, thetobacco is flue tobacco and the step of subjecting to microwaveradiation is carried out within about 24 to about 72 hours post-harvest, even more preferably within about 24 to about 36 hourspost-harvest.

In still other embodiments of the process, the harvestedtobacco is maintained under above-ambient température conditionsin a controlled environment prior to the step of subjecting tomicrowave radiation.

Preferred aspects of the process include a step, prior tosubjecting a tobacco leaf which preferably includes the stem tomicrowave radiation, of physically pressing the leaf to squeeze

01124C excess mcisture therefrom, to ensure more uniform drying by themicrowave unir. This step car. be conveniently carried out bypassing the leaf through a pair of appropriately spaced rotatingcylindrical rollers prior to entering the microwave cavity.

In yet additional preferred embodiments of the invention,the microwave radiation has a frequency of about 900. to about2500 MHz, and is applied to the plant for a period of at leastabout 1 second, and preferably from about 10 seconds to about 5minutes at a predetermined power level. The power level used ηβ generally détermines the length of time to which the tobacco is subjected to the microwave radiation, and can range from about500 to about 1000 watts when using conventional kitchen-typemicrowave ovens, up to several hundred or more kilowatts forcommercial, multimode applicators. Preferred power levels usingήΛ applicators designed to handle single leaves range from about 2 to about 75 kilowatts, more preferably from about 5 to about 50kilowatts, which permit relatively rapid treatment to be carried out.

It is also preferred in accordance with the présent 2U invention that the microwave radiation is applied to the leaf or portion thereof for a time sufficient to effectively dry theleaf, without charring, so that it is suitable for humanconsumption.

The présent invention also seeks to subject tobacco leaves -je to microwave radiation to orevent normal accumulation of at least one tobacco-spécifie nitrosamine, such as N'-nitrosonornicotine, 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N'-nitrosoanatabine and N'-nitrosoanabasine.

01 1 2 4 U

The présent invention in its broadest forms also encompassesa tobacco product comprising non-green tobacco suitable for humanconsumption and having a lower content of at least one tobacco-specific nitrosamine than conventionally cured tobacco.

In preferred embodiments, the non-green tobacco product hasa TSNA (NNN, NNK, NAB and NAT) content of less than .2 /xg/g, morepreferably less than about .15 jxg/g, and even more preferablyless than about .1 /xg/g, an NNN content of less than about .15/xg/g, more preferably less than about .10 /xg/g, and even morepreferably less than about .05 gg/g, and an NNK content of lessthan about .002 gg/g, more preferably less than about .001 Mg/g,and even more preferably less than about .0005 /xg/g.

The présent invention is also directed to a tobacco productcomprising dried yellow tobacco suitable for human consumptionand having a lower content of at least one tobacco-specificnitrosamine than conventionally cured tobacco. In preferredembodiments, the yellow tobacco product has a TSNA (NNN, NNK, NABand NAT) content, an NNN content, and an NNK content within theabove preferred ranges.

In other embodiments, the non-green or yellow tobaccoproduct comprises non-green or yellow tobacco suitable for humanconsumption, and having a TSNA (NNN, NNK, NAB and NAT) contentwithin about 25% by weight of the content of such TSNA in thefreshly harvested green tobacco crop frcm which the product wasmade. It is more preferred that the non-green or yellow tobaccoproduct hâve a TSNA content within abouc 10% by weight, morepreferably within about 5% by weight and most preferablyessentially approximating (e.g. within an amount up to several 011240 percent by weight) the content of such TSNA in the freshlyharvested tobacco crop from which the product was made. It isalso preferred that the non-green or yellow tobacco productcomprises non-green or yellow tobacco suitable for human consumption, and having content of at least one TSNA selected 5 from NNN, NNK, NAB and NAT, which is within about 25% by weight,preferably within about 10% by weight, more preferably withinabout 5% by weight and most preferably essentially approximating(e.g. within an amount up to several percent by weight) of the content of the corresponding TSNA or TSNAs in the freshly 1b harvested green tobacco crop from which the product was made.

In yet additional embodiments of the invention, the non- green or yellow tobacco product comprises non-green or yellowtobacco suitable for human consumption, and having a TSNA (NNN, NNK, NAB and NAT) content which is at least about 75% by weight, 15 preferably at least about 90% by weight, more preferably at least about 95% by weight, and most preferably at least about 99% by weight lower than the content of such TSNA in a tobacco product of the same type made from the same tobacco crop as the product of the invention, but which was cured in the absence of microwave2ü radiation or other techniques designed to reduce TSNA content.It is also preferred that the non-green or yellow tobacco productcomprises non-green or yellow tobacco suitable for humanconsumption, and having a content of at least one TSNA selectedfrom NNN, NNK, NAB and NAT which is at least about 75% by weight,preferably at least about 90% by weight, more preferably at leastabout 95% by weight, and most preferably at least about 99% byweight lower than the content of the corresponding TSNA or TSNAs 01 1 2 4 Ü in a tobacco product of the same type made from the same tobaccocrop as the product of the invention, but which was cured in theabsence of microwave radiation or other techniques designed toreduce TSNA content. A preferred form of the présent invention relates to ah tobacco product comprising tobacco having a reduced content ofat least one tobacco-specific nitrosamine, produced by a processcomprising subjecting the tobacco, while the tobacco is uncuredand susceptible to having formation of at least one tobacco-specific nitrosamine arrested, to microwave radiation. 10

In another embodiment, the présent invention is directed toa method for reducing the content of at least one tobacco-specif ic nitrosamine in cured brown tobacco, comprising rehydrating the cured brown tobacco, and subjecting the rehydrated tobacco to microwave radiation at15 a predetermined energy level for a predetermined length of time.

Similarly, the présent invention includes within its scope a tobacco product comprising cured brown tobacco having a reduced content cf at least one tobacco-specific nitrosamine, produced by a process comprising2Ü rehydrating the cured brown tobacco, and subjecting the rehydrated tobacco to microwave radiation ata predetermined energy level for a predetermined length of time.

In yet another embodiment, the présent invention relates toa method of manufacturing a tobacco product, comprising i ~ L-' subjecting harvested tobacco leaves to microwave radiation, while said leaves are uncured and in a State susceptible to having the amount of tobacco-specific nitrosamines reduced or 10 011240 formation of tobacco-specific nitrosamines arrestsd, for asufficient time to reduce the amount of or substantially preventformation of at least one tobacco-specific nitrosamine in theleaves, and 5 forming the tobacco product comprising the microwaved leaves, the tobacco product being selected from cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum andlozenges.

It has also been discovered that forms of electromagnetic I, radiation having higher frequencies and shorter wavelengths thanthe microwave domain discussed above and in more detail below,can be used to achieve the basic objects of the présent invention - réduction or substantial élimination cf TSNAs in tobaccoProducts, by treating the tobacco with such energy forms in the I same time frame post-harvest as discussed above with regard to the microwave embodiment. Thus, the présent invention alsorelates to a method for reducing the amount of or preventingformation of nitrosamines in a harvested tobacco plant,comprising , subjecting at least a portion of the plant to radiation

.U having a frequency higher than the microwave domain, while saidportion is uncured and in a State susceptible to having theamount of nitrosamines reduced or formation of nitrosamines arrested, for a sufficient time to reduce the amount of orsubstantiallv prevent formation of at least one nitrosamine.

As with the microwave embodiments, it is preferred that inthe process of the invention, the step of subjecting to radiationhaving a frequency higher than the microwave domain is carried 11 011240 out on a tobacco leaf or portion thereof after onset of yellowingin the leaf and prior to substantial accumulation of tobacco-specific nitrosamines in the leaf. It is also preferred that inthe process of the invention, the step of subjecting to suchradiation is carried out prior to substantial loss of the leaf'scellular integrity. Preferred energy sources capable cfproducing such radiation are described further below, and includefar-infrared and infrared radiation, UV (ultraviolet radiation),soft x-rays or lasers, accelerated particle beams such asélectron beams, x-rays and gamma radiation.

Brief Description of the Drawings FIG. I is a photograph illustrating "yellow" Virginia fluetobacco aged 24 to 72 hours post-harvest. FIG. 2 is a photograph illustrating low-nitrosaminemicrowaved "yellow" Virginia flue tobacco in accordance with theprésent invention.

Figure 3 is a partial, side-perspective illustration of amobile, commercial-scale microwave applicator which can beemployed to carry out the microwave treatment in accordance withthe présent invention.

Petailed Description Of The Invention

It has been said that the practice of tobacco curing is moreof an art than a science, because curing conditions during anvgiven cure must be adjusted to take into account such factors asvarietal différences, différences in leaves harvested fromvarious stalk positions, différences among curing barns where 12 used, and environment al variations during a sine- e, season or overdifferent seasons, especially weather fluet:,:· : ions when air-curing. For example, the practice of fin..·· - ^ring is empiricalto a certain degree, and is optimally c- rrïed out by individuals 5 who hâve accumulated expérience in »:· s art over a significant period of time. See, e.g., C-..-le et al, "Chemical and

Biochemical Changes During The Flue Curing Of Tobacco," RecentAdvances In Tobacco Science, Vol. 21, pp. 81 et seq., SymposiumProceedings 49th Meeting Chemists' Research Conférence, September 24-27, 1995, Lexington, Kentucky (hereinafter "Peele et al").

IJ

Thus, one of ordinary skill in the art of tobacco curing wouldunderstand that the outer parameters of the présent invention,in its broadest farms, are variable to a certain extent dependingon the précisé confluence of the above factors for any given 5 harvest.

In one preferred embodiment, the présent invention isfounded on the discovery that a window exists during the tobaccocuring cycle, in which the tobacco can be treated in a mannerthat will essentially prevent the formation of TSNA. Of course,the précisé window during which TSNA formation can be effectivelyeliminated or substantially reduced dépends on the type oftobacco, method of curing, and a number of other variables,including those mentioned above. In accordance with thispreferred embodiment of the présent invention, the windowcorresponds to the time frame post-harvest when the leaf isbeyond the fresh-cut or "green" stage, and prior to the time atwhich TSNAs and/or nitrites substantially accumulate in the leaf;this time frame typically corresponds to the period in which the 13 011240 leaf is undergoing the yellowing process or is in the yellowphase, before the leaf begins to turn brown, and prior to thesubstantiel loss of cellular integrity, Unless otherwise clearfrom the context, the terms "substantiel" and "significant" asused herein generally refer to prédominant or majority on arelative scale, give or take. During this time frame, the leavesare susceptible to having the formation of TSNAs substantiallyprevented, or the content of any already formed TSNAs reduced,by exposing the tobacco to microwave radiation at a predeterminedenergy level for a predetermined length of time, as discussedfurther below. This microwave treatment essentially arrests thenatural formation of TSNAs, and provides a dried, golden yellowleaf suitable for human consumption. If TSNAs hâve already begunto substantially accumulate, typically toward the end of theyellow phase, the application of microwave energy to the leaf inaccordance with the invention effectively arrests the naturalTSNA formation cycle, thus preventing any further substantialformation of TSNA. When yellow or yellowing tobacco is treatedin this fashion at the most optimal time in the curing cycle, theresulting tobacco product has TSNA levels essentiallyapproximating those of freshly harvested green tobacco, whilemaintaining its flavor and taste.

In another embodiment, the présent invention relates totreatment of cured (brown) tobacco to effectively reduce the TSNAcontent of that cured tobacco, by rehydrating cured tobacco andsubjecting the rehydrated cured tobacco to microwave radiation,as described further below. 14 011240

The présent invention is applicable te treatment of theharvested tobacco which is intended for human consumption. Muchresearch has been performed on tobacco, with particular referenceto tobacco-specific nitrosamines. Freshly harvested tobaccoleaves are called "green tobacco" and contain no knowncarcinogens, but green tobacco is not suitable for humanconsumption. The process of curing green tobacco dépends on thetype of tobacco harvested. For example, Virginia flue (bright)tobacco is typically flue-cured, whereas Burley and certain darkstrains are usually air-cured. The flue-curing of tobaccotypically takes place over a period of five to seven dayscompared to one to two+ months for air-curing. According toPeele et al, flue-curing has generally been divided into threestages: yellowing (35-40°C) for about 36-72 hours (althoughothers report that yellowing begins sooner than 36 hours, e.g.,at about 24 hours for certain Virginia flue strains), leaf drying(40-57°C) for 48 hours, and midrib (stem) drying (57-75°C) for48 hours. Many major Chemical and biochemical changes beginduring the yellowing stage and continue through the early phasesof leaf drying.

In a typical flue-curing process, the yellowing stage iscarried out in a barn. During this phase the green leavesgradually lose color due to chlorophyll dégradation, with thecorresponding appearance of the yellow carotenoid pigments,According to the review by Peele et al, the yellowing stage cfflue-curing tobacco is accomplished by closing external air ventsin the barn, and holding the température at approximately 35°-37°C. This process utilizes a controlled environment, maintains 15 011240 the relative humidity in the barn at apprcximately 85%, limitsmoisture loss from the leaves, and allows the leaf to continuethe metabolic processes begun in the field. The operatorconstantly moniteurs the progress of the cure, primarily byobserving the loss of chlorophyll and green color from theleaves, and the development of the desired lemon to golden orangeleaf color.

With one particular variety of Virginia Élue tobacco onwhich testing has been carried out as described herein, freshlyharvested green tobacco is placed in a barn for about 24-48 hoursat about 100-110°F until the leaves turn more or less completelyyellow (see Figure 1) . The yellow tobacco has a reduced moisturecontent, i.e., from about 90 weight % when green, versus about70-40 weight % when yellow. At this stage, the yellow tobaccocontains essentially no known carcinogens, and the TSNA contentis essentially the same as in the fresh-cut green tobacco. ThisVirginia flue tobacco typically remains in the yellow stage forabout 6-7 days, after which time the leaves turn from yellow tobrown. The brown Virginia flue tobacco typically has a moisturecontent of about 11 to about 15 weight percent. The conversionof the tobacco from yellow to brown results in formation andsubstantial accumulation of nitrosamines, and an increasedmicrobial content. The exact mechanism by which tobacco-specificnitrosamines are formed is not clear, but is believed to beenhanced by microbial activity, involving microbial nitratereductases in the génération of nitrite during the curing process. 16 011240

Tobacco-spécifie nitrosamines are believed to be formed uponreaction of amines with nitrite-derived nitrosating species, suchas NO2, N2Oj and N2O4 under acidic conditions. Weirnik et aldiscuss the postulated formation of TSNAs at pp. 43-45; a briefsynopsis is set forth below.

Tobacco leaves contain an abundance of amines in. the formof amino acids, proteins, and alkaloids. The tertiary aminenicotine (referenced as (1) in the diagram below) is the majoralkaloid in tobacco, while other nicotine-type alkaloids are thesecondary amines nornicotine (2) , anatabine (3) and anabasine(4) . Tobacco also generally contains up to 5% of nitrate andtraces of nitrite.

Nitrosation of nornicotine (2) , anatabine (3) , and anabasine(4) gives the corresponding nitrosamines: N'-nitrosonornicotine(NNN, 5), N'-nitrosoanatabine (NAT, 6), and N'-nitrosonabasine(NAB, 7) . Nitrosation of nicotine (1) in aaueous solutionaffords a mixture of 4-(N-nitrosomethyiamino)-1-(3-pyridyl)-1-butanone (NNK, 8) (NNN, 5) and 4-(N-nitrosomethylamino)-4-(3-pyridyl)-1-butanal (NNA, 9). Less commonly encountered TSNAsinclude NNAL (4-N-nitrosomethylamino)-1-(3-pyridyl)-1-butanol, 10) , iso-NNAL (4-N-nitrosomethylamino)-4 -(3-pyridyl)-1-butanol, 11) and iso-NNAC (4-(N-nitrosomethylamino)-4 -(3-pyridyl)-butanoicacid, 12). The formation of these TSNAs from the correspondingtobacco alkaloids is shown schematically below, using thedésignations 1-12 above (reproduced from Weirnik et al, supra,p. 44) : 17 011240 P1’

N-NO 11

COOH

Im-NNAC

l w Niiatin, 1 » Nornlcotlne 3«Anaubine ^"Anabuine

It is now generally agreed that green, freshly harvested tobacco contains virtually no nitrite or TSNA, and that these compounds are generated during curing and storage of tobacco.

Studies hâve been made during the past decade to try to détermine the events related to the formation of TSNA during curing cf5 tobacco, and several factors of importance hâve been identified.These include plant génotype, plant maturity at Harvest, curingconditions and microbial activity.

Studies nave shown that nitrite and TSNA accumulate on air-curing at the time intervals starting after the end of yellowingand ending when the leaf turns completely brown, e.g., 2-3 weeksafter harvest for certain air-cured strains, and approximatelya week or so after harvest in flue-cured varieties. This is the 18 011240 time during which loss of cellular integrity occurs, due tomoisture loss and leakage of the content of cells into thieintercellular spaces. Therefore, there is a short window in timeduring air- curing when the cells hâve disintegrated, making thenutrition available for microorganisms. Weirnik et al hâvesuggested that nitrite may then substantially accumulate as aresuit of dissimilatory nitrate réduction, thus renderingformation of TSNA possible.

There are a few published reports on the effects ofmicrobial flora on the tobacco leaf during growth and curing andon cured tobacco, as cited in Weirnik et al. Howevsr, theinvclvement of microbial nitrite reductases in the génération ofnitrate during curing is presumed. When cell structure is brokendown after the yellow phase, and nutrients are made accessibleto invading microorganisms, these may produce nitrite underfavorable conditions, i.e., high humidity, optimal températureand anoxia. There is normally a rather short "window" in timewhen the water activity is still sufficiently high, and the oeilstructure has disintegrated.

In accordance with the présent invention, the formation ofTSNAs in tobacco is substantially prevented or arrested bysubjecting the harvested leaves to microwave radiation under theconditions described herein. In one preferred embodiment, thetobacco leaves are exposed to the microwave energy at a timebetween the onset of yellowing and the substantial loss ofcellular integrity. For optimal results, it is preferred to passthe harvested leaves through the microwave field as singleleaves, as opposed to stacks or piles of leaves. Treating the 19 01124Ü leaves in this raanner has faeen. determined to completely orsubstantially prevent the formation of tobacco-specificnitrcsamines, including the known carcinogens NNN and NNK.

In accordance with preferred embodiments of the présentinvention, non-green and/or yellow tobacco products can beobtained which are suitable for human consomption, and which hâvea lower content of at least one tobacco-specific nitrosamine thanconventionally cured tobacco. Green or fresh-cut tobacco isgenerally unsuitable for human consumption as noted above; "non-green" as used herein raeans means the tobacco has at least lostthe majority of chlorophyll, and includes without limitationpartially yellow leaves, full yellow leaves, and leaves whichhâve begun to turn brown in places. In preferred embodiments,the non-green tobacco product has a TSNA (NNN, NNK, NAB and NAT)content of less than .2 gg/g, more preferably less than about .15μ<3/ς, and even more preferably less than about .1 gg/g, an NNNcontent of less than about .15 gg/g, more preferably less thanabout .10 gg/g, and even more preferably less than about .05gg/g, and an NNK content of less than about .002 gg/g, morepreferably less than about .001 gg/g, and even more preferablyless than about .0005 gg/g. As noted above, given the number offactors which can influence TSNA formation in tobacco, one ofordinary skill in the art would understand that these numbers arenot absolute, but rather preferred ranges.

The présent invention is also directed to a tobacco productcomprising dried yellow tobacco suitable for human consumptionand having a lower content of at least one tobacco-specificnitrosamine than conventionally cured tobacco. In preferred 20 011240 embodiments, the yellow tobacco product has a TSNA (NNN, NNK, NABand NAT) content, an NNN content, and an NNK content within theabove preferred ranges.

In other embodiments, the non-green or yellow tobaccoproduct comprises non-green or yellow tobacco suitable for humanconsumption, and having a TSNA (NNN, NNK, NAB and NAT) contentwithin abouc 25% by weight of the content of such TSNA in thefreshly harvested green tobacco crop from which the product wasmade. It is more preferred that the non-green or yellow tobaccoproduct hâve a TSNA content within about 10% by weight, morepreferably within abour 5% by weight and most preferablyessentially approximating (e.g. within an amount up to severalpercent by weight) the content of such TSNA in the freshlyharvested tobacco crop frcm which the product was made. Forexample, the présent invention permits tobacco products to bemade which hâve a TSNA content within the above-described rangesas to amounts, whereas normally cured tobacco from the same cropwould typically generate many times the amount of TSNA in thefresh-cut tobacco. The présent invention can effectively lockin the low amounts of nitrosamines found in fresh-cut greentobacco. It is also preferred that the non-green or yellowtobacco product comprises non-green or yellow tobacco suitablefor human consumption, and having content of at least one TSNAselected frcm NNN, NNK, NAB and NAT, which is within about 25%by weight of, preferably within abouc 10% by weight of, morspreferably within about 5% by weight of, and most preferablyessentially approximating (e.g., within an amount up to severalpercent by weight) the content of the corresponding TSNA or TSNAs 21 011240 in the freshly harvested green tobacco crop from which theproduct was made. In other words, the content of, e.g., NNN inthe tobacco of the invention falls within the above ranges vis-a-vis the amount of NNN in the fresh-cut green tobacco, or theamount of NNN + NNK in the tobacco of the invention falls withinthe above ranges vis-a-vis the amount of NNN + NNK in the fresh-cut green tobacco, etc. in making these comparisons, the fresh-cut green tobacco is preferably analyzed for TSNA content within about 24 hours after harvest.

In yet additional embodiments of the invention, the non-green or yellow tobacco product comprises non-green or yellowtobacco suitable for human consumption, and having a TSNA (NNN,NNK, NAB and NAT) content which is at least about 75% by weight,preferably at least about 90% by weight, more preferably at leastabout 95% by weight, and most preferably at least about 99% byweight lower than the content of such TSNA in a tobacco productof the same type made from the same tobacco crop as the productof the invention, but which was cured in the absence of microwaveradiation or other steps specifically designed to reduce the TSNAcontent. It is also preferred that the non-green or yellowtobacco product comprises non-green or yellow tobacco suitablefor human consumption, and having a content of at least one TSNAselected from NNN, NNK, NAB and NAT which is at least about 75%by weight, preferably at least about 90% by weight, morepreferably at least about 95% by weight, and most preferably atleast about 99% by weight lower than the content of thecorresponding TSNA or TSNAs in a tobacco product of the same type(e.g., comparing a cigarette to another cigarette) made from the 22 011240 same tobacco crop as the product of the invention, but which wascured in the absence of microwave radiation or other techniquesfor reducing TSNA content. In these embodiments, the TSNA weight% comparisons can be made by taking, for example, a cigarette , made using dried yellow tobacco in accordance with the présent invention, and taking a cigarette made from tobacco from the samecrop as the dried yellow tobacco was made from, but curing it byconventional means without subjecting it to microwave radiation.

The yellow stage, in which the step of subjecting the tobacco leaf to microwave radiation is oreferably carried out, can be broadly defined in any one of the following ways: (a) by examining the color of the leaf, when the green color has substantially given way to a yellowish color,· (b) by measuring the percent of chlorophyll conversion to sugars; (c) by observing the onset of either nitrite formation or nitrosamine génération,1b which typically coincide with the end of the yellow phase, or (d)by measuring the moisture content of the leaves, e.g., when theyhâve a moisture content from about 4 0 to about 70 percent byweight. If the microwave radiation is applied to green tobacco, the arrestation or prévention of nitrosamine formation is not kü observed. However, when microwave energy is applied after theonset of yellowing and prior to the loss of cellular integrityor substantial accumulation of TSNAs in the leaf, the observedréduction in the amount of, or prévention of formation ofnitrosamines is dramatic and unexpected, as shown by the datadiscussed below.

The optimal tirne for subjecting the harvested tobacco to the microwave radiation during the yellow phase varies depending on 23 011240 a number of factors, including varietal différences,environmental variations, etc. Thus, within the time framebeginning with. onset of yellowing (defined, e.g,, by a loss ofthe majority of green color in the leaf) through the time atwhich the leaf substantially loses cellular integrity (as itturns brown), cne of ordinary skill in the art coula déterminethe optimal time for carrying out the microwave treatment for anygiven variety of tobacco. For example, for a given génotype,sample leaves could be tested by the procedures described hereinto measure either nitrite or TSNA content, to identify therelative time in a given cure cycle at which significant TSNAaccumulation begins, or identify the transition phase in whichloss of cellular integrity occurs. While subjecting the leavesto the microwave radiation prior to significant TSNA accumulationis the most preferred form of the method of the présentinvention, the principles of the invention can also be appliedto tobacco leaves which are in the process of forming, and hâveaiready accumulated significant amounts of TSNAs. When themicrowaving is carried out at this latter stage, furtherformation of TSNAs can be effectively arrested. However, oncethe leaves are fully cured, TSNA levels hâve essentiallystabilized, and application of microwave radiation is ineffectiveto reduce the TSNA context, except under rehydration conditions described below.

Upon being subjected to microwave radiation in accordancewith the présent invention, the tobacco leaf generally has areduced moisture content, i.e. less than about 10% by weight, andoften approximately 5%. If desired, the leaf can be rehydrated 24 011240 back to the typical moisture range for brown, cured tobacco(e.g., about 11-15% for Virginia flue) before manufacturing intotobacco products such as cigarettes.

The presenc invention is applicable to ail strains oftobacco, including flue or bright varieties, Burley varieties,dark varieties, oriental/Turkish varieties, etc. Within theguidelines set fortn herein, one of ordinary skill in the artcould détermine the most efficient time in the cure cycle forcarrying out the microwave step to achieve the objecta andadvantages of the présent invention.

Preferred aspects of the process include a step, prior tosubjecting a tobacco leaf which preferably includes the stem tomicrowave radiation, of physically pressing the leaf to squeezeexcess moisture therefrom, to ensure more uniform drying by themicrowave unit. This step can be conveniently carried out bypassing the leaf through a pair of appropriately spaced rotatingcylindrical rollers prior to entering the microwave cavity. Sucha pressing step will aid in wringing moisture from the stem and,to a lesser extent, the midrib and larger veins, and lead to abetter and more evenly dried product. The rollers can be madeof hard rubber, plastic or steel and be of any desired length,and are preferably spaced about one-eighth to about one-quarterinch apart, but the distance is preferably selected so as toaccomodate the thickness of a single leaf, which can vary. Therollers can be belt or chain driven by an appropriately selectedmotor. Besides rotating rollers, other types of squeezing orpressing means could be used to accomplish the same resuit, if 25 011240 desired, as would be apparent to one of ordinary skill in the art.

The above-described preferred embodiment of pressing the leaves permits more high-speed production to be carried out; since the stems do not hâve to be eut out, and the microwave timeb can be reduced. This embodiment is particularly advantageous fortobacco leaves destined to be used in cigarettes, which typicallycontain some tobacco stems as part of a blend. Alternatively,the pressing step can be oraitted if desired, in applicationswhere the stem is trimmed from the leaves and discarded. 10

In another preferred embodiment, instead of pressing the leaves or cutting out the stems, the leaves can be subjected to a steam treatment prior to microwaving. As with the pressing step, steaming the whole leaves, including the stems, has been demonstrated to more evenlv distribute the moisture in the stems and larger veins, thus leading to more uniform drying of the entire leaves upon microwaving. As a resuit, the entire leaves including the stems can be used in tobacco products when this particular technique is employed. Although the details would be apparent to one of ordinary skill in the art, successful resultsd’.l' hâve been obtained when the leaves hâve been placed in a suitablesteam vessel for a time sufficient to allow the leaves to becomesomewhat soft and pliable, generally from about 30 seconds up toabout five minutes.

The principles of the présent invention can also be appliedto brown or already cured tobacco, which has been rehydrated.In such cases, while important and unexpected réductions in theamount of the TSNAs, particularly NNN and NNK, are observed when 26 011240 rehydrated brown tobacco is subjected to microwave radiation, theresults are not as dramatic as when the invention is applied touncured yellow tobacco, prior to the time when substantialquantities of TSNAs or nitrites hâve accumulated in the leaves;

Nonetheless, the addition of moisture to the cured leaves, such 5 as by spraying with enough water to effectively soak the leaves,followed by microwaving the rehydrated leaves, reduces thecontent of TSNAs as demonstrated in the following Examples.

As noted above, when treating cured or brown tobacco, microwaving alone has little effect on the nitrosamine content.

1U

However, it has been determined that rehydration of the curedtobacco prior to subjecting it to microwave radiation facilitâtesthe action of the microwave energy in reducing nitrosamines. Inone preferred embodiment, the cured tobacco product is rehydrated by adding an appropriate amount of water, generally at least 15 about 10% by weight, up to the maximum absorption capacity, directly to the leaves. Exposure of the rehydrated leaves to microwave radiation, in the saine manner as described herein with regard to the uncured tobacco, reduces the nitrosamine content, as shown below. The leaves can be wetted in any suitable2:j fashion. If the cured tobacco is in a form other than leaves,such as reconstituted "sheet" tobacco, it can similarly berehydrated with, e.g.z '10-70% by weight water, and then microwaved. Suitable microwave condition can be selecteddepending on the degree to which the leaves are re-wetted, buttypically fall within the parameters discussed above formicrowaving yellow tobacco. 27 011240 in accordance with the présent invention, microwaving of the rehydrated brown tobacco can preferably reduce the TSNA (NNN, NNK, NAB and NAT) content, measured individually or collectively, by at least about 25% by weight, more preferably by at least about 35% by weight, and even more preferably by at least about5 5 0% by weight from the TSNA levels ccntair.ed the cured browntobacco prior to rehydration.

The term "microwave radiation" as used herein refers toelectromagnetic energy in the form of microwaves having afrequency and wavelength typically characterized as fallingwithin the microwave domain. The term "microwave" generallyrefers to that portion of the electromagnetic spectrum which liesbetween the far-infrared région and the conventionalradiofrequency spectrum. The range of microwaves extends froma wavelength of anproximately 1 millimeter and frequency of about300,000 MHz to wavelength of 30 centimeters and frequency ofslightly less than about 1,000 MHz. The présent inventionpreferably utilizes high power applications of microwaves,typically at the lower end of this frequency range. Within thispreferred frequency range, there is a fundamental différence 20 between a heating process by microwaves and by a classical way, such as by infrared (for example, in cooking): due to a greater pénétration, microwaves generally heat quickly to a depth several centimeters while heating by infrared is much more superficial.

In the United States, commercial microwave apparatuses, such as25 kitchen microwave ovens, are available at standard frequencies of approximately 915 MHz and 2450 MHz, respectively. These frequencies are standard industrial bands. In Europe, microwave 28 01124Ü frequencies of 2450 and 896 MHz are commonly employed. Under properiy balanced conditions, however, microwaves of other frequencies and wavelengths would be useful to achieve the objects and advantages of the présent invention.

Microwave energy can be generated at a variety of power5 levels, depending on the desired application. Microwaves aretypically produced by magnatrons, at power levels of 600-1000watts for conventional kitchen-level microwave apparatuses(commonly at about 800 watts), but commercial units are capableof generating power up to several hundred kilowatts, generally 10 by addition of modular sources of about 1 kilowatt. A magnatroncan generate either pulsed or continuous waves of suitably highfrequency.

The applicator (or oven) is a necessary link between the microwave power generator and the material to be heated. For 15 purposes of the présent invention, any desired applicator can beused, so long as it is adapted to permit the tobacco plant partsto be effectively subjected to the radiation. The applicatorshould be matched to the microwave generator to optimize powertransmission, and should avoid leakage of energy towards the »pi ’

«C J outside. Multimode cavities (microwave ovens), the dimensionsof which can be larger than several wavelengths if necessary forlarge samples, are useful. To ensure uniform heating in theleaves, the applicator can be equipped with a mode stirrer (ametallic moving device which modifies the field distributioncontinuously), and with a moving table surface, such as aconveyor belt. The best résulta are attained by single leaf 29 011 2 4 Ü thickness exposure to microwave radiation, as opposed to stacksor piles of leaves.

In preferred embodiments of the invention, the microwave conditions comprise microwave frequencies of about 900 MHz to about 2500 MHz, more preferably about 915 MHz and about 2450 MHz,5 power levels of from about 600 watts up to 300 kilowatts, morepreferably from about 600 to about 1000 watts for kitchen-typeapplicators and from about 2 to about 75 kilowatts, morepreferably from about 5 to about 50 kilowatts, for commercial multimode applicators. The heating time generally ranges from lü at least about 1 second, and more generally from about 10 seconds up to about 5 minutes. At power levels of about 800-1000 watts the heating time is preferably from about 1 minute to about 2½ minutes when treating single leaves as opposed to piles or stacks. For commercial-scale applicators using higher power1b levels in the range of, e.g., 2-75 kilowatts, heating times would be lower, ranging from about 5 seconds up to about 60 seconds, and generally in the 10-30 second range at, say, 50 kilowatts, again for single leaves as opposed to piles or stacks. Of

course, cne of ordinary skill in the art would understand that2U an optimal microwave field density could be determined for any given applicator based on the volume of the cavity, the power level employed, and the amount of moisture in the leaves.

Generally speaking, use of higher power levels will recuire less time during which the leaf is subjected to the microwavekb radiation.

However, the above-described conditions are not absolute,and given the teachings of the présent invention, one of ordinary 30 011240 skill in the art would be able to détermine appropriate microwaveparameters. The microwave radiation is preferably applied to theleaf or portion thereof for a time sufficient to effectively drythe leaf, without charring, so that it is suitable for humanconsumption. It is also preferred to apply the microwaveradiation to the leaf or portion thereof for a time and at apower level sufficient to reduce the moisture content to belowabout 20 % by weight, more preferably about 10% by weight.

Ref erring now to Figure 3, an embodiment of a commercialscale microwave applicator is depicted in partial, perspectiveview. In particular, a Microdry 300 kW microwave tobacco dryingSystem 1 is shown, comprising a mobile truck frame 2 (front endat right side of drawing not shown) , a conveyorized microwaveoven 3 which interiorly includes four modular oven cavities ofsingle wall construction (which can be suitably constructed from3003H14 aluminum), each cavity measuring approximately 15' inlength x 84" in width x 48" in height. Each cavity is equippedwith four access doors located two per side. The doors aredouble interlocked to prevent accidentai exposure to microwaveenergy.

In Figure 3, an automatic cutting mechanism 5 is shown,including multiple (e.g., twelve) rotating blades for removingthe stem from the leaves 4. The cutter can be a straight stripapproximately 3.4" in width down the center of the leaves,manually fed. An appropriate guard can be provided, if desired,to prevent insertion of operators' hands, Although Figure 3depicts a stem cutting mechanism, as noted above the whole leavescan be used in accordance with other embodiments of the 31 011240 invention. Thus, in place of the cutting mechanism, theapparatus could employ a steam vessel or a pair of rollers forpressing moisture from the leaves.

Returning to Figure 3, after the stem cutting operation theeut tobacco leaves 6 are conveyed by a belt conveyor 7 to themain microwave oven 3 housing the four cavities. In oneembodiment, the System has an oven length of approximately 78feet. Leading into and within the oven, the conveyor System canalternatively comprise multiple, e.g., six, variable speedpolypropylene belts arranged in such a way so as to allow the eutstems to fall from between the pairs of belts and into a hopperlocated below the belts (not shown). The belts will then carrythe eut tobacco leaves through one of two traps located one ateach of the cavities, designed to contain the microwave energy,and then into a selected cavity where each leaf is subjected tomicrowaving in accordance with the principles of the inventiondescribed above. After being microwaved, the conveyor carriesthe leaves through the cavity exit, through an oven dischargetrap and out of the oven where they are then conveyed intoappropriate vessels to be taken for further Processing.

To remove the moisture laden air from the cavities and oven,an exhaust System including suitable blowers providingrecirculating air can be included in the System (see moistureexhaust vents, item 8 being one labeled as représentative, inFig. 3) . Also, if desired, the interior of the oven can betempérature controlled by appropriately spaced circulating airconvection heating sources so that the interior of the ovenoutside the microwave cavities is maintained at a preferred 32 011240 constant température, e.g., 160-180° F, during conveyorizedtransport of the leaves. In a mobile System such as depicted inFigure 3 for field usage, the electrical requirements can besupplied by a pair of conventional diesel-powered generators 9', 10. Of course, the microwave dryinc System can also be operatedin a fixed location, if desired, powered by conventionalelectrical sources.

Each of the four cavities within oven 3 in Fig. 3 receivesmicrowave energy from a corresponding Microdry Model IV-75microwave power source. The microwave energy enters eachrespective cavity via a splitter through two ports located in thetop of each cavity. A mode stirrer is located below the portsin each cavity to assist in the distribution of the microwaveenergy. Each microwave power unit is acompletely self-containedcabinet that houses the required components to operate a 75 kWmagnetron. Controls for the microwave power are located on thecabinet. The units are designed for unattended continuousoperation in an industrial environment. Each microwave powergenerator may be located at each cavity, or at a distance fromthe cavity. However, at a distance of 50', the transmission linelosses will be about 2%. Each power generator providesadjustable microwave energy for industrial operation. The outputpower is adjustable from 0 to about 75 kW at the FCC assignedfrequency of 915 MHz, and is controlled by a solid state controlcircuit manually adjusted by a control knob on the panel or byremote control with a 4-20 milliamp control signal from a processcontroller. While the circuitry will control the power outputfrom zéro, the frequency spectrum becomes broad at levels below 33 011240 about 5 kW. The power generator for each cavity is basically a direct current power supply operating an industrial magnetron which is operated and protected by circuit fonctions designed for automatic and manual operation. The electrical functions of the generator are monitored by meters on the control panel, located5 on cabinet door. The metering includes anode current, anodevoltage, output power, filament current, electromagnet currentand reflected power. Operation of the electromechanicalinterlock functions are monitored by designated lamps located onthe control panel. Each microwave power generator cabinet hasfull width doors for maximum accessibility to the components.A built-in electromagnetic interférence shielding enclosurehouses the magnetron and associated microwave components. A doorallows for installation of the magnetron and electromagnet. The

System includes a circulator and water load, mounted inside the 1b

cabinet, which functions as an isolator to protect the magnetronin the event of a high reflected power condition. The microwavepower generator uses both forced air and water for cooling thebeat producing components. The magnetron and electromagnet arewater cocied by a closed loop demineralized water System. A 20 separate water source and a heat exchanger can be used to coolthe water in this loop. The separate water source also flowsthrough a water to air heat exchanger inside the cabinet to coolthe cabinet air. A high pressure centrifugal blower providescooling to the magnetron output window and the cathode structure. r'_ _7

Water and cabinet températures are interlocked in the control power chain. Typical reference data for each microwave generator in a System of this are as follows: 34 011240

Power inputPower outputMagnetron tube 95 KVA, 440-480 VAC, 3 phase, SO Hz75 kW at 915 +/- 10 MHz

CTL, CWM 75 I

Typical magnetron operation reference data are as follows: 1Ü AC filament voltage 11.4 V Filament current 85 A DC anode voltage 17 KV Anode current 5.0 A DC electromagnet current 4.3 A Efficiency 80% 15 2Li

Further, a typical microwave generator can employ a carbon Steelenclosure and hâve an output connection (WR 975 waveguide) in thetop of the cabinet at an appropriate location.

In a throughput test, a microwave tobacco drying systemgenerally designed as described above was effective to eliminateover 80% of the moisture content of the leaves. In particular,in one raeasured sample, 15 pounds of leaves with an assumedinitial water content of 85 wt% and solids content of 15 wt% wasconveyed through a microwave cavity in single leaf thickness ata rate of about 180 Ibs per hour. The leaves were weighed afterexiting the cavity. The ending weight was 4.S lbs., or 31% ofthe initial weight. Thus, based on the initial assumed watercontent, therer remained 2.35 pounds of water in the leaves,ccrresponding to 18.5% of the initial water content.

As disclosed in FIG. 2, the microwave treatment of yellowtobacco in accordance with the présent invention preferablyresults in a dried, golden-colored tobacco product. The datapresented herein establish that such dried tobacco, in its 35 011240 unsmoked form, has dramatically reduced carcinogenicnitrosamines, particularly NNN and NNK, as opposed to normallycured tohacco.

It has also been discovered that concentrated forms ofelectromagnetic radiation (i.e., concentrated as distinguishedfrom general exposure to sunlight or electric light within thevisible spectrum) having higher frequencies and shorterwavelengths than the microwave domain discussed above, can beused to achieve the basic objects of the présent invention -réduction or substantial- élimination of TSNAs in tobaccoProducts, by treating the tobacco with such energy forms inapproximately the same time frame post-harvest as discussed abovewith regard to the microwave embodiment. In other words, thesame general and preferred techniques and principles discussedabove regarding microwaving can be applied when such an alternateenergy source is used; for example, the tobacco is treated withsuch radiation at approximately the same time f rames post-harvest, the leaves can be de-stemmed, pressed between rollersor steamed prior to irradiation, etc.

However, while such alternate energy sources hâve beendetermined to significantly and desirably reduce or substantiallyeliminate or prevent formation of TSNAs, none of the otherembodiments tested to date hâve been as effective in drying theleaves as the microwave technique described in detail. Thus,when using such an alternate energy source, it may be préférableto subject the irradiated tobacco leaves to further processingto complété the curing cycle, such as ccmbining the irradiationstep with a subséquent oven-drying or tumble-drying step. 36

01 1 2 4 U

In particular, it is believed that any electromagneticradiation source, and accelerated particle beams such as électronbeams, having frequencies higher than the microwave domain withinthe conventional electromagnetic spectrum are operative tosignificantly reduce, substantially eliminate and/or preventformation of TSNAs when tobacco is uncured and in a Statesusceptible to having the amount of TSNAs reduced or formationthereof arrested. On a scale within the electromagnetic spectrumwhere microwaves are generally defined as inclusive of thoseforms of electromagnetic radiation having a frequency of 10L1 Hzand a wavelength of 3 x 10'3 meters, such energy sources include,without limitation, far-infrared and infrared radiation havingfrequencies of about 1012 to 1014 Hz and wavelengths of 3 x 10'4 to3 x 10'6 meters, ultraviolet radiation having frequencies ofabout 1O1S to 1018 Hz and wavelengths of 3 x 10'8 to 3 x 10‘10meters, soft x-rays or lasers, cathode rays (a stream ofnegatively charged électrons issuing from the cathode of a vacuumtube perpendicular to the surface), x-rays and gamma radiationtypically characterized as having frequencies of 1021 Hz andhigher at corresponding wavelengths.

As would be apparent to one of ordinary skill in the art,the greater the dose of radiation delivered by the energy source,the less time the leaves need to be subjected thereto to achievethe desired results. Typically, radiation application times ofless than one minute, preferably less than 30 seconds and evenmore preferably less than about ten seconds are needed when usingsuch higher frequency radiation sources. Defined another way,radiation application times of at least about one second are 37 011240 preferred. However, as shown in the Examples below, the exposure rate car. be controlled to deliver the radiation dosage over time, if desired. For example, 1 megarad of radiation can be delivered instantaneously (as with the électron beam accelerator discussed below in Example 17), or at a predetermined exposure rate (as5 exemplified by the closed chamber gamma irradiation testingdiscussed below in Example 19, wherein 1 megarad (10 kGrey) ofirradiation was delivered at an exposure rate of about .8 megaradper hour). When using high frequency radiation sources, it ispreferred to use an amount of radiation which achieves at least 1(6 a 50% réduction in TSNAs, in comparison to untreated samples.

While the particular radiation dosages and exposure rate will dépend on the particular equipment and type of radiation source being applied, as would be apparent to one of ordinary skill in the art, it is generally preferred to subject the tobacco samoles1b to radiation of from about .1 to about 10 megarads, morepreferably from about .5 to about 5 megarads, and more preferablyfrom about .75 to about 1.5 megarads.

As illustrated in the following Examples, testing has been

carried out on various tobacco samples using an accelerated2D

électron beam, a CO2 laser and gamma radiation as exemplary ofthese additional radiation sources. In each instance, theuncured, irradiated tobacco samples were demonstrated to containsignificantly reduced and/or substantially eliminated TSNA contents. ’j

In yet another embodiment of the invention, treating the tobacco while in its susceptible State in a recirculating air

convection oven has also been demonstrated to reduce the TSNA 38 01 1 2 4 Ü content, aibeit with reduced leaf quality. Unlike a conventionai baking oven which is not as effective in lowering TSNA content and also lowers the tobacco quality, heating in a recirculating air convection oven at températures of from about 100° to about 500° F, for periods ranging from one hour at the low end down to5 about 5 minutes at the high end of the température scale, canalso effectively reduce the content of or arrest formation ofTSNAs in tobacco while in its susceptible State as definedherein. Even more preferablv, an oven combining recirculatingair convection heat and microwave radiation can shorten theheating time while providing improved quality to the leaves. Forexample, when a convection oven alone is used, the veins andstems are not completely dried at the time the lamina are dried,thus leading to overdried and crumbly lamina sections. Combining „ the microwave treatment with recirculating convection oven heat can improve the leaf quality by giving a more uniformly driedproduct.

In another aspect, the présent invention relates to a methodfor reducing or substantially eliminating the content of tobacco- _ spécifie nitrosamines in a human or animal subject who smokes, an cnews or otherwise ingests tobacco, by, providing for consumptiona tobacco product having significantly reduced or substantially eliminated TSNAs.

Subjecting the uncured tobacco to microwave or otherradiation energy is demonstrated herein to be effective toprovide tobacco hâve surprisingly low nitrosamine contents.These oechniques can be facilitated by peeling and disposing ofthe stem down one-third to one-half length of the tobacco leaf, 39 011240 especially in cases where the stem is te be discarded and th.emoisture-wringing or steaming steps described above are notemployed. Where the stem is removed in this manner, therésultant microwaved tobacco leaf does not require the use of -athrasher machine since the undesirable part of the stem isalready removed. As a resuit, the typical loss of tobaccoproduct associated with thrashing is eliminated, reducing tobaccowaste by approximately 10% to 30%.

The improved tobacco of the présent invention can besubstituted in whole or part for normally-cured tobacco in anytobacco product, including cigarettes, cigars, chewing tobacco,tobacco chewing gum, tobacco lozenges, tobacco pouches, snuff,or tobacco flavoring and food additives. For the purposes ofsmoking, the présent invention provides a less noxious odor whilemaintaining good smoking characteristics and providing fullflavor with normal nicotine content. For the purposes ofchewing, snuff, pouch and food additives, the tobacco of theprésent invention nas a rich, pleasant flavor.

The présent invention is new illustrated by reference to thefollowing examples, which are not intended to limit the scope ofthe invention in any manner.

Example 1

Virginia flue tobacco was harvested, and the leaves wereplaced in a curing barn at about 100-110°F to begin the flue-curing process. Samples 1-3 were taken from the barn after theleaves had turned yellow, about 24-36 hours post-harvest. Sample1 was a lamina sample, stripped of the midrib, and baked in a 40 01124 Ü convection air oven at about 400-500°C for about 1 hour, which browned the lamina. Sample 2 was a yellow leaf, placed in a

Goldstar Model MA-1572M microwave oven (2450 MHz), and heated on the high power setting (1,000 watts) while rotatir.g for about 2½ minutes. Sample 3 was a yellow leaf, untreated, used as a5 control. Samples 4 and 5 remained in the curing barn underelevated température of about 1BO°F, Sample 4 being dried outsidethe racks and Sample 5 inside the racks. Sample 6 was a cured,brown leaf, having underwent the normal flue-cure process.

Analyses were performed on each sample to détermine NNN,NAT, NAB and NNK contents. In this and the following examples,"TSNA" représenta the sum of these four tobacco-specificnitrosamines. Sample work-up and extraction followed a typicalprocedure for analysis of TSNAs (see, for example, Burtcn et al., "Distribution of Tobacco Constituants in Tobacco Leaf Tissue. 1b 1. Tobacco-specific Nitrosamines, Nitrate, Nitrite andAlkaloids", J. Agric. Food Chem., Volume 40, No. 6, 1992), andindividual TSNAs were quantified on a Thermedics Inc. TEA Model543 thermal energy analyzer coupled to a Hewlett-Packard Model5890Ά gas chromatograph. The results are shown in Table 1 below. 20

Ail data in each table below are presented in micrograms of thenitrosamine per gram of sample (i.e., parts per million or ^g/g): 41 011240 TABLE 1

Sample # NNN NAT + NAB NNK TSNA 1 - yellow baked lamina 0.0310 0.843 <0.0004 0.1157 2 - yellowmicrowaved <0.0004 <0.0006 <0.0005 <0.0014 3 - yellowcontrol 0.0451 0.1253 0.0356 0-.2061 4 - rapiddryingoutsideracks 0.6241 1.4862 1.2248 3.3351 5 - rapiddryinginsideracks 0.7465 1.5993 1.3568 3.7044 6 - regularflue-cured 1.0263 1.7107 2.2534 4.9904

Example 2

Virginia flue tobacco was harvested. Sample 7 was a fresh-cut, green leaf used as a control, wnile Sample 8 was a fresh-cutgreen leaf which was subjected to microwave radiation in amultimode microwave applicator manufactured by MicroDry ofLouisville, Kentucky, operating at 2450 MHz at 2.5 kilowatts, forabout 20 seconds. Samples 9-12 were made from normally flue-cured brown tobacco. Sample 9 was tobacco from a formedcigarette; Sample 10 was loose, shredded tobacco for makingcigarettes; Samples 11 and 12 were the same as Samples 9(cigarette) and 10 (loose), respectively, except that each wassubjected to the same microwave conditions as Sample 8. TSNAcontents were analyzed in the same manner as in Example 1. Theresults are shown in Table 2 below: 42 011240

Table 2

Sample # NNN NAT + NAB NNK TSNA 7 - fresh leaf control <0.0104 0.126 0.0005 0.126 8 - freshleaf -microwaved 0.029 0.135 0.0004 0.164 9 - control cigarette 1.997 3.495 2.735 8.226 10 - control loose 2.067 3.742 2.982 8.791 11 - cigarette microwaved 2.056 3.499 2.804 8.359 12 - loosemicrowaved 2.139 3.612 2.957 8.707

Example 3

The following cigarette brands shown in Table 3 werepurchased at random at various retailers in Lexington, Kentucky,and analyzed for TSNA content using the procedure described inExample 1 :

Table 3

Sample # Code No. NNN NAT + NA3 NNK TSNA 13- Marlboro -king-pc 288292 3.565 4.538 1.099 9.202 14- Marlboro -king-pc 288292 4.146 4.992 1.142 10.279 15- Marlboro -king-pc 288292 3.580 4.290 1.106 8.977 43 011240

Sample # Code No. NNN NAT + NAB NNK TSNA 16- Marlboro -king-pc 288292 3.849 4.748 1.130 9.728 17- Marlboro-lights-100's-bx 288192 4.604 5.662 1.223 11.489 18- Marlboro-lights-100's-pc 288182 3.471 3.859 1.211 8.541 19- Marlboro -lights- 100's-pc 2881B2 3.488 4.136 1.074 8.698 20- Marlboro-lights-100's-pc 288182 3.566 4.240 1.164 8.970 21- Winston-100's-pc 123143 2.311 2.968 1.329 6.608 22- Winston- king 123103 2.241 2.850 1.256 6.348 23- Winston- king-bx 125123 2.162 2.831 1.326 6.319 24- Winston- king-bx 123123 2.577 3.130 1.207 6.914 25- Winston- king-pc 123103 1.988 2.563 1.234 5.786 26- Winston- lights-100's-pc 123133 2.161 2.706 1.258 6.124 27- Winston-lights-100's-pc 123133 2.189 2.699 1.262 6.150 44 01124Ü

Sample # Code No, NNN NAT + NAB NNK TSNA 28- Winston-lights-1001s-pc 123133 2.394 3.385 2.330 8.109

Example 4

Virginia flue tobacco was harvested, and the leaves were placed in a curing barn at about 100-110eF to begin the flue- curing process. After the leaves turned yellow, about 24-36 hours post-harvest, they were taken out of the barn and5 microwaved in Goldstar Model MA-1572M microwave oven (2450 MHz), high power setting (1000 watts), for about 2½ minutes while rotating. The leaves were effectively dried by this procedure, although they did not turn brown, but instead retained their

golden-yellow color. The leaves were shredded and made intoV cigarettes. Samples 29-33 were taken from a batch labeled RedFull Flavor, while Samples 34-38 were taken from a batch labeledblue Light. Samples 39-42 were cigarettes purchased at a healthfood store, under the brand Natural American Spirit. Samples 29-42 were analyzed for TSNA content using the procedure describedin Example 1, and the results are shown in Table 4 below: 45 01 1240

Table 4

Sample # NNN NAT + NAB NNK TSNÀ 29-RED FULL FLAVOR REP 1 0.138 0.393 <0.0005 0.532 30-RED FULL FLAVOR REP 2 0.192 0.231 <0.0005 0.423 31-RED FULL FLAVOR REP 3 0.129 0.220 <0.0007 0.349 32-REDFULL FLAVOR REP 4 0.145 0.260 <0.0007 0.406 33-RED FULL FLAVOR REP 5 0.140 0.293 <0.0006 0.434 AVG 0.149 0.279 <0.0006 0.429 STD 0.022 0.062 0.0001 0.059 34-BLUE LIGHT REP 1 0.173 0.162 <0.0005 0.335 35-BLUE LIGHT REP 2 0.046 0.229 <0.0005 0 . 275 36-BLUE LIGHT REP 3 0.096 0.188 <0.0005 0 .285 37-BLUE LIGHT REP 4 0.067 0.215 <0.0005 0.282 38-BLUE LIGHT REP 5 0.122 0.218 <0.0005 0.341 AVG 0.101 0.202 <0.0005 0.304 STD 0.044 0.024 0.0000 0.028 39- NATURAL AMERICAN SPIRIT 0.747 1.815 1.455 4.017 46 011240

Sample # NNN NAT + NAB NNK TSNA 40- NATURAL AMERICAN SPIRIT 0.762 1.805 1.458 4.025 41- NATURAL AMERICAN SPIRIT 0.749 1.826 1.464 4.039 42- NATURAL AMERICAN SPIRIT 0.749 1.760 1.462 3.971 AVG 0.752 1.802 1.460 4.013 STD 0.005 0.025 0.004 0.025 STD in the Tables herein is the standard déviation for the average of the samples shown.

Examole S

Virginia fine tobacco was harvested, and the leaves wereplaced in a curing barn at about 100-110°F to begin the flue-curing process. Samples 43-44 were taken from the barn after theleaves had turned yellow, about 24-3S hours post-harvest, andsubjected to microwave radiation in the MicroDry multimodeapplicator described above for about 20 and 30 seconds,respectively, at a power level of about 6 kilowatts . Samples 43and 44 were dried, golden-yellow leaves after the microwaving.Samples 45-51 were made from brown, cured leaves having underwentthe normal flue-cure process. Sample 45 was a control; Samples46 and 47 were baked in a convection oven preheated to about 400-500 °F for about 1 and about 3 minutes, respectively; and Samples48 and 49 were subjected to microwave radiation (915 MHz) in aWaveguide applicator Model WR-975, a large multimode oven 47 011240 manufacturée! by MicroDry (power settings from 0-75 KW) at 50kilowatts for about 10 and 40 seconds, respectively. Samples 50and 51 were eut (reconstituted sheet) tobacco made from the flue-cured leaves. Sample 50 was subjected to microwave radiation inthe Waveguide microwave oven at 50 kilowatts for about 1.5minutes, while Sample 51 was baked in a convection oven preheatedto about 400-500 °F for about 3 minutes. These samples wereanalyzed for TSNA content using the procedure described inExample 1, and the results are shown in Table 5 below:

Table 5

Sample # NNN NAT + NAB NNK TSNA 43-20 SECMICROWAVE <0.0105 <0.1068 <0.0007 <0.1181 44-30 SECMICROWAVE <0.0103 <0.1065 <0.0004 <0.1172 45-CONTROLNO MICRO 0.92 2.05 3.71 6.68 46-OVEN 1 MIN 1.14 2.41 5.10 8.66 47-OVEN 3 MIN 0.89 2.06 2.68 5.64 48- WAVEGUIDE 10 SEC 50 KW 1.00 2.31 3.29 6.59 49- WAVEGUIDE 40 SEC 50 KW 0.62 1.55 1.69 3.86 50-CUT TOBACCO WAVEGUIDE 1.5 MIN 50 KW 4.22 4.91 0.99 10.12 51-CUT TOBACCO OVEN 3 MIN 4.76 5.60 1.08 11.44 48 01124 Ü

Example 6

Virginia flue tobacco was harvested, and the leaves were placed in a curing bar at about 100-110°F to begin the flue- curing process. Samples 52-55 were cigarettes made from yellow t_ tobacco which had been pulled from the barn after about 24-36 hours, and subjected to Microwave radiation in a Goldstar microwave oven, Model MA-1572M (2450 MHz), for about 2 minutes on the high power setting (1000 watts). For comparison, Samples 61 and 62 were cigarettes made from leaves which had undergone the normal flue-cure process, without microwave treatment.1Li

Sample 56 was a cured leaf; Sample 57 was post-yellow, not fullycured; Sample 58 was a cured lamina, while Samples 59 and 60 werecured midribs. TSNA contents were measured as in Example 1, andthe results are set forth in Table 6 below: 49 011240

Table 6

Sample # NNN NAT + NAB NNK TSNA 52- Goldsmokecigarettes 0.12 0.23 0.03 0.38 53- Goldsmoke II, 85 mm 0.062 0.326 0.016 0.404 54- Goldsmoke 85 mm 0.128 0.348 0.029 0.504 55- Goldsmoke100's Sample 3 0.166 0.317 0.047 0.531 56-Sample M-M 3.269 4.751 0.833 8.853 57-Sample B-C 0.267 0.720 0.954 1.941 58-Lamina M-C 0.933 1.456 1.968 4.356 59-WM 0.996 1.028 0.408 2.432 60-SM 1.745 1.753 0.306 3.804 61- Goldsmoke control 1.954 1.544 0.492 3.990 62- Goldsmoke control 1.952 1.889 0.424 4.265

Example 7

Virginia Élue tobacco was harvested. Samples 63 and 66 wereuncured, fresh-cut green tobacco, although over a week lapsedbefore TSNA measurements were taken, so some air-curing had takenplace. The remaining leaves were piaced in a curing barn atabout 100-110°F to begin the flue-curing process. Sample 68 wasa leaf taken from the barn after it had turned yellow, about 24-36 hours post-harvest, and was subjected to microwave radiation 50 011240 in the Waveguide multimode applicator described above, for about40 seconds at 25 kilowatts.

Samples 64/65 (leaves) and 67/70 (reconstituted sheettobacco, or "eut" tobacco) demonstrate the effects of the présentinvention when cured tobacco is rehydrated, then subjected tomicrowave radiation. Samples 64 and 65 were leaf samp.les havingundergone the normal flue-curing process; however, Sample 64 wasrehydrated by running under an open faucet for about 5-10seconds. The leaf absorbed significant moisture. Each ofSamples 64 and 65 was then microwaved in the Waveguide multimodeapplicator for about 40 seconds at 25 kilowatts. Samples 67 and70 were reconstituted sheet tobacco samples, made from curedleaves. Sample 67 was rehydrated by adding water so that asignificant quantity was absorbed, then microwaved under theconditions described for Sample 64. Sample 70 was netmicrowaved. Samples 69, 71 and 72 are additional cured leaf samples, used as Controls. The TSNA contents were measured asin Example 1, and the results are shown in Table 7 below:

Table 7

Sample # NNN NAT + NAB NNK TSNA 63-CONTROL UNCURED 0.010 0.263 0.000 0.274 64-CURED 40 SEC(WET) 0.737 1.252 1.893 3.882 65-CURED 4 0 SEC 0.767 1.520 2.229 4.516 66-UNCURED 40 SEC 0.010 0.261 0.000 0.272 51 01124ü

Sample # NNN NAT + NAB NNK TSNA . 67-CUT TOBACCO CURED 40 SEC (WET) 0.769 1.328 0.308 2.405 68-UNCURED 40 SEC 25 KW WAVEGUIDE 0.051 0.244 0.014 0.308 69-CURED CONTROL 0.866 1.548 2.545 4.960 70-CONTROLCUT TOBACCO 1.872 2.536 0.789 5.197 71-CONTROL'AL' WHOLELEAF 0.230 0.606 0.746 1.582 72-SML WHOLE LEAF 0.413 0.884 1.514 2.810

Example 8

Virginia flue tobacco was harvested, and the leaves wereplaced in a curing barn at about 100-110° F to begin the flue-curing process. Sample 73 was a leaf taken from the barn afterit turned yellow, about 24-36 hours post-harvest, and microwavedin a Goldstar Model MA-1572M for about 2 minutes on the highsetting. Samples 74-76 were flue-cured in the normal way.Sample 74 was a cured control. Samples 75 and 76 were rehydratedas in Example 7 (Sample 64), then each sample was subjected tomicrowave radiation in the MicroDry applicator (2450 MHz) forabout 20 seconds (Sample 75) and about 40 seconds (Sample 76),respectively, at power levels of abouc 6 kilowatts. Samples 77-79 were reconstituted sheet tobaccc, made from the flue-curedleaves. Sample 77 was a control, while Samples 78 and 79 wererehydrated as in Example 7 (Sample 67). Samples 78 and 79 were 52 011240 microwaved in the MicroDry applicator for about 30 seconds each;Sample 78 rested on the oven bottom, while Sample 79 was raisedup several inches by resting the sheet sample on a styrofoam cup,which permitted more uniform heating. TSNA contents weremeasured as in Example 1, and the results are set forth in Table8 below:

Table 8

Sample # NNN NAT + NAB NNK TSNA 73-yellow/microwaved 0.052 0.260 <0.0004 0.313 74-A-controlleaf,cured 1.168 1.904 1.662 4.734 75-B- 20 SECONDS 0.791 1.705 1.115 3.611 76-C 40SECONDS 0.808 1.624 1.160 3.592 77- CONTROL- sheet 4.417 3.697 0.960 9.073 78-30 SECONDS 2.755 2.553 0.644 5.952 79-30 SECONDS ELEVATED 1.606 1.732 0.350 3.687 53 011240

Example 9

Samples 80-81 were Redman chewing tobacco purchased atretail. Sample 80 was a control, while Sample 81 was microwavedin a Goldstar Model MA-1572M for about 1-2 minutes on the highpower setting. Samples 82-83 were Skoal snuff purchased atretail. Sample 82 was a control, while Sample 83 was microwavedin the same manner as for Sample 81. TSNA contents weremeasured, and the results are shown in Table 9 below:

Table 9

Sample # NNN NAT + NAB NNK TSNA 80-CHEWING TOBACCO BEFORE 0.712 0.927 0.975 1.713 81-CHEWINGTOBACCO AFTER 0,856 0.906 0.122 1.884 82-SNUFFBEFORE 4.896 10.545 1.973 17.414 83-SNUFF AFTER 6.860 14.610 1.901 23.370

Example 10

To test whether TSNAs accumulate over time even after yellowtobacco is microwaved in accordance with the présent invention,additional samples (designated -A) of the cigarettes tested inExample 4, Samples 29, 35 and 39 (control) were retested for TSNAcontent more than seven months after the TSNA contents were firstmeasured, as reported in Example 4. The results are shown belowin Table 10: 54

Table 10 011240

Sample # NNN NAT NAB NNK TSNA 29A-RED FF REP#1 0.1109 0.1877 0.1078 0.0015 0.4079 35A-BLUE LIGHT REP #2 0.0508 0.1930 0.1075 0.0012 0.3525 3 9A-NATURALAMERICANSPIRIT REP #1 0.6151 1.2357 0.1072 0.9302 2.8882

Example 11

Virginia flue tobacco was harvested, and the leaves wersplaced in a curing barn at about 100-110°F to begin the flue-curing process. After the leaves turned yellow, about 24-36hours post- harvest, they were taken from the barn and subjectedto microwave radiation in a Goldstar Model MA-1572M microwaveoven for about 2 to 2½ minutes, en the high power setting. Eachof the leaves was a golden-yellow colcr, and effectively dried.Certain samples, designated by "ground", were later ground upinto a flour-like substance, which would be useful as, forexample, a gum, lozenge or food additive. After more than sixmonths from the time the leaves were microwaved, the TSNA contentof the following samples were measured using the proceduredescribed in Example 1. The results are shown in Table 11 below: 55

Table 11 011240

Sample # NNN NAT NAB NNK TSNA 84- ground 0.0013 0.0018 0.0018 0.0015 0.0064 85- ground 0.0469 0.0341 0.0011 0.0009 0.0831 86- ground 0.0009 0.0582 0.0013 0.0011 0.0615 87- ground 0.0113 0.1078 0.1078 0.0015 0.2284 88- ground 0.0569 0.1401 0.1071 0.0009 0.3051 89- ground 0.0109 0.1642 0.1073 0.0011 0.2835 90- ground 0.0008 0.0011 0.0011 0.0009 0.0038 91- ground 0.0009 0.0012 0.0012 0.0010 0.0044 92- ground 0.0012 0.1059 0.0017 0.0014 0.1101 93- ground 0.0013 0.0529 0.0019 0.0015 0.0576 94- ground 0.0012 0.0613 0.0017 0.0014 0.0657 95- ground 0.0506 0.0989 0.0013 0.0010 0.1518 96- ground 0.0017 0.0894 0.0024 0.0019 0.0954 97- ground 0.0012 0.0017 0.0017 0.0014 0.0061 98- ground 0.0016 0.0023 0.0023 0.0019 0.0082 99- ground 0.0342 0.0016 0.0016 0.0013 0.0386 100- ground 0.0014 0.0020 0.0020 0.0016 0.0070 101-leaf 0.0013 0.0539 <0.0019 <0.0016 0.0587 102-leaf 0.0009 0.0012 <0.0012 <0.0010 0.0043 56 011240

Sample # NNN NAT NAB NNK TSNA 103- shredded leaves 0.0202 0.0327 <0.0007 <0.0006 0.0542

Examole 12

Virginia flue tobacco was harvested, and the leaves were placed in a curing barn at about 100-110°F to begin ths flue- curing process. Samples 104 and 105 were leaf samples naving undergone the normal flue-curing process, without microwave5 treatment. Sample 104 was a cured midrib, while Sample 105 wascured a lamina. Sample 106 was yellow oobacco, taken from thebarn after ths leaves had turned yellow, about 24-36 hours postharvest. After being taken from the barn, the leaves were

subjected to microwave radiation in a Goldstar Model MA-1572M 1Ü microwave oven for about 2-2½ minutes, on the high power setting.Each of the leaves was a golden-yellow color, and effectivelydried. Certain of the dried leaves were further processed in aconventional manner to forra a tobacco extract, which was V designated Sample 107 for purposes of analysis. The TSNAcontents of Samples 104-107 were measured using the proceduredescribed in Example 1. The results are shown in Table 12 below. 57

Table 12 011240

Sample # NNN NAT &amp; NAB NNK TSNA 104 - control midrib 0.083 0.180 <0.003 0.266 105 - control lamina 0.928 1.367 2.613 4.908 106 - microwaved leaves <0.004 <0.006 <0.005 <0.015 107 - microwaved extract <0.004 <0.005 <0.004 <0.013

Sxample 13

Virginia flue tobacco was harvested, and the leaves were placed in a curing barn at about 100-110’F to begin the flue- curing process. Samples 108 and 109 were leaf samples havingb undergone the normal flue-curing process. Sample 108 was a curedlamina, while sample 109 was a cured midrib. Samples 110 and 111were yellow tobacco, taken from the barn after the leaves hadturned yellow, about 24-36 hours post-harvest. After being taken from the barn, Samples 110 and 111 were heated in a circulating 1c air convection oven, a Sharp Carousel Convection/Microwave ModelNo. R-9H84B. Sample 110 was rapidly heated at about 300°F forbetween 5-10 minutes. Sample 111 was more slowly heated at lowertempératures, starting at about 100°F and being stepped up toabout 150°F after more than 10 minutes, for a total heating time 1j of over 20 minutes. The TSNA contents of Samples 108-111 weremeasured using the procedure described in Sxample l. The resultsare shown in Table 13 below. 58

Table 13 01 1 2 4 Ü

Sample # NNN NAT &amp; NAB NNK TSNA 108 - control lamina 1.267 2.509 1.377 5.153 109 - control midrib <0.004 0.464 <0.004 0.472 110 - convection- rapid <0.004 <0.005 <0.004 <0.013 111 - convection- slow <0.003 <0.004 <0.003 <0.010 .

Although the convection oven heating was shown to reduce TSNA levels, the quality of the tobacco was inferior to thatobtained upon microwaving in accordance with preferred examplesof the invention. Also, the heating time is necessarily longerthan when using the microwave radiation treatment or other formsof higher frequency radiation. In particular, the convectionheating was unable to lock the color in at the desired golden-yellow, and the lamina had a tendency to be over-dried andtherefore brittle, while the veins and midrib were not completelydried. In contrast, in accordance with the most preferredembodiments of the invention, the. microwaved leaves wereeffectively dried and retained a golden-yellow color after beingsubjected to treatment, while staying supple and pliable forfurther processing, especially as cigarettes. In convection-ovenproduced samples, the lamina when dried has a tendency to crumbleinto a dust and small tobacco particles. 59 011240

Example 14

Kentucky burley tobacco was harvested, and the leaves wereprocessed as follows after they began to turn yellow, about 24-48hours post-harvest. Samples 112-117 were leaf samples from thisbatch, further processed as follows. Sample 112 was microwavedunder approximately the sanie conditions as Sample 106 in Example12. The leaves were a golden-yellow color and effectively driec.Samples 113, and 114 and 117 were heated in the saine circulatingair convection oven as described in Example 13, Sample 113 beingheated under approximately the same conditions as Sample 110,Sample 114 being heated under approximately the same conditionsas Sample 111, and Sample 117 being heated at about 350°F forabout 20 minutes. The quality of Samples 113, 114 and 117 wasakin to that of Samples 110 and 111, as described in Example 13.Samples 115 and 116 were heated in the Sharp CarouselConvection/Microwave oven described in Example 13, using thecombined microwave (30%)/convection (300°C) feature until theleaves were effectively dried to golden-yellow color. The TSNAcontents of Samples 112-117 were measured using the proceduredescribed in Example 1. The results are shown in Table 14 below: 60 011240

Table 14

Sample # NNN NAT &amp; NAB NNK TSNA 112 - microwaved <0.007 <0.010 <0.008 <0.025 113 - convection <0.003 <0.004 <0.003 <0.010 114 - convection <0.012 <0.017 <0.014 <0.043 115 -microwave(30%) /convection <0.002 <0.003 <0.003 <0.008 116 -microwave(30%)/convection <0.002 <0.003 <0.002 <0.007 117 - convection 0.131 0.156 <0.003 0.290

Example 15

Virginia flue tobacco was harvested, and the leaves wereplaced in a curing barn at about 100-110°? to begin the flue-curing process. Samples 118-120 were leaf samples, taken fromthe barn after the onset of yellowing, and shortly thereaftersubjected to microwave radiation in a conventional kitchen-typemicrowave oven for about 2 to 2 1/2 minutes until the leaveswere effectively dried to a golden-yellow color, without burning or charring. Samples 121-123 were samples of Kentucky burley 1ü tobacco, harvested and processed after the onset of yellowing ineach instance as follows. Sample 121 was placed in aconventional steam tumble dryer typically used in the tobaccoindustry, at a température of about 200°?, until the leaves had browned and dried somewhat. Sample 122 was microwaved in the 1b above-referenced Goldstar microwave on high for about 2 minutes, 61 011240 the rehydrated with water and placed in the tumble dryer toimpart a slight browning to the leaves which is believed toenhance the flavor. Sample 123 was treated like Sample 122,except that it was microwaved for 1 minute and was not rehydratedbefore being put in the tumble dryer. TSNA contents werelikewise measured as in Example 1, and the results are shown in

Table 15 below:

Table 15

Sample # NNN NAT &amp; NAB NNK TSNA 113 <0.003 0.150 <0.003 0.156 119 <0.003 <0.004 <0.003 <0.010 120 <0.002 <0.003 <0.003 <0.008 121 0.486 1.059 <0.003 1.548 122 <0.004 <0 . 005 <0.004 <0.013 123 <0.003 <0.004 <0.004 <0.011

Example 16

North Carolina burley tcbacco was harvested, and the leaves 1,; were processed as follows after they began to turn yellow, about2-3 days post-harvest. Sample 113 was a leaf sample which hadbeen subjected to microwave radiation in the same type ofGoldstar microwave oven described above, on the high powersetting for about 2 minutes. After microwaving the leaves were -9 r a golden yellow color, and effectively dried. The TSNA content 52 011240 was measured using the procedure described in Example 1. Theresults are shown in Table 16 below:

Table 16

Sample # NNN NAT &amp; NAB NNK TSNA 118 0.024 0.048 <0.001 0.073

Example 17

This example demonstrates the effectiveness of usingélectron beam radiation to reduce the content of, orsubstantially prevent formation of TSNAs, in yellow tobaccosamples. North Carolina burley tobacco was harvested. Samples119-122 were leaf samples, air-cured by hanging outside in anormal manner, until the leaves were effectively dried and brown.Sample 119 was untreated as a control. Samples 120 and 121 weresubjected to électron beam radiation on a conveyor belt using aDynamitron Electron Beam Accelerator, manufactured by RadiationDynamics, Inc. of Edgewood, N.Y., at an exposure rate of 1megerad. Sample 122 was subjected to microwave radiation in theGoldstar microwave oven for about 2 minutes on the high powersetting. Sample 123 was taken from the tip of a burley leafafter it had begun to turn yellow. Sample 124 was a leaf stemportion, taken from the same plant as Sample 123, and was stillsomewhat green-colored. Samples 125 and 126 were whole leafburley samples, at the yellow stage. Each of Samples 123-126 wassubjected to électron beam radiation using the above-describingDynamitron, in the same manner and under the same exposure rateas Samples 120 and 121, as described above. The above sampleswere tested to measure TSNA content according to the procedure 63 011240 set forth in Exampie 1, and the results are shown in Table 17below:

Table 17

Sample # NNN NAT &amp; NAB NNK TSNA 119 -control,cured 3 . 6351 1.0847 0.0470 •4.7668 120 - highpower,cured 6.5718 3.7037 0.4368 10.7123 121 - low power, cured 4.4771 1.6112 0.7468 6.8369 122 - microwave,cured 4.8974 1.6393 1.1200 7.6567 123 - yellow tip 0.1812 0.3667 0.0013 0.5492 124 - green stem 0.1918 0.8310 0.0016 1.0243 125 - whole leaf 0.0014 0.1019 0.0016 0.1048 126 - whole leaf 0.0646 0.2465 0.0019 0.3130

Although the above data show that électron beam radiation is effective to prevent formation of substantral quantities oftobacco-specific nitrosamines in the yellow leaf samples tested,the leaves were not dried as effectively as wnen leaves in asimilar State post-harvest were subjected to microwave radiation,as described in other examples of this application. Thus,commercial applications of the électron beam irradiation processmay require an additional drying step, such as conveying theirradiated leaves through a conventional drying oven, tofacilitate the curing process. 64 011240 11!

Example 18

This example demonstrates that high energy teams producedby lasers are also effective to achieve the low TSNA goals of theprésent invention. A CO2 laser made by Luxar Corp., Model LX-20SP, was used, to irradiate yellow Virginia flue tobacco leaves,at about 2-3 days post-harvest. A NovaScan handpiece was usedunder the superpuise E program, which détermines the speed ofapplication in patterns per second. A setting of E10 was used,which delivers 10 patterns per second. Eight sutsamples ofleaves, T-l to T-8, were irradiated according to the followingprotocol : E10 - 2 watts E10 - 4 watts T-l - 1 pass each side T-5 - 1 pass each side T-2 - 2 passes each side T-6 - 2 passes each side T-3 - 3 passes each side T-7 - 3 passes each side T-4 - 4 passes each side T-8 - 4 passes each side

At 2 watts, approximately 120 mJ. of energy is delivered ineach scan or pass, while at 4 watts, approximately 240 mJ isdelivered in each such scan.

SutsamplesT-l to T-4 were mixed and combined together toforn leaf Sample. 127, which was evaluated for TSNA content in thesame manner as descrited in Example 1. Sutsamples T-5 to T-8were similarly mixed and combined together to form leaf Sample 65 128, which was likewise evaluated for TSNA content. The results are shown in Table 18 below:

Table 18

Sample # NNN NAT &amp; NA3 NNK TSNA 127 0.1031 0.2025 0.0006 0.3061 128 0.1019 0.1287 0.0010 0.2315

As with the samples described in Example 17, the CO-, laser 5 irradiated samples were not dried as effectively as the microwaved samples, although the TSNA contents were low, andtherefore an addïtional drying scep could be employed to speedthe curing process. Also, after the C0= laser irradiation butprior to TSNA testing, six of the eight subsamples turned -ï somewhat brown, with no apparent effect on TSNA content.

Examale 19

This example demonstrates that gamma radiation is alsoeffective in preventing formation of significant amounts of TSNAin yellow tobacco. Virginia flue tcbacco was taken about 2-3 - days post harvest, just after the leaves had turned yellow. Each of Samples 129-132 was taken from the lamina portion of theyellow leaves, and subjected in an enclosed chamber to gammairradiation of 10 kGrey (1 megarad) at an exposure rate of 8kGrey (.8 megarad) per hour, for a total exposure time of about75 minutes. The irradiated samples were subsequently evaluatedas to TSNA content in the same fashion as described above, and the results are shown below in Table 19: €6 0112 4 û

Table 19

Sample # NNN NAT &amp; NAB NNK TSNA 129 0.098 0.225 0.057 0.380 130 <0.001 <0.001 <0.001 <0.003 131 <0.001 <0.001 <0.001 <0.003 132 0.033 0.079 <0.001 0.113

It will be apparent to those skilled in the art that variouschanges and, modifications may be made in the preferredembodiments without departing from the spirit and scope of theclaimed invention. Therefore, the foregoing description isintended to be illustrative only and should not be viewed in alimiting sense. 67

Claims (50)

1. ΟΊ1240 What is claimed is.·

   1. A process for reducing the amount of or preventingformation of nitrosamines in harvested tobacco plant, comprising (i) a step of (a) removing stems from the tobacco leaves-, (b) pressing the tobacco leaves to remove excess moisture or (c) 5 subjecting the tobacco leaves to a steam treatment, and (ii) a step of subjecting at least a portion of the plant to microwave radiation, while said portion is uncured and in a State susceptible to having the amount of nitrosamines reduced or formation of nitrosamines arrested, for a sufficient time to1ij reduce the amount of or substantially prevent formation of atleast one nitrosamine, wherein said subjecting to microwaveradiation is carried out on a tobacco leaf or portion thereofafter onset of yellowing in the leaf and prior to substantialaccumulation of tobacco-specif ic nitrosamines in the leaf, andwherein said tobacco leaf or portion thereof is arranged insingle layer thickness without stacking or piling of the leaves.
2. 2. The process according to claim 1, wherein said step is(b) or (c) and the tobacco leaves contain stems.
3. 3. A process for reducing the amount of or preventing 2. L; . formation of nitrosamines in harvested tobacco plant, comprisingsubjecting at least a portion of the plant to a concentrated form of radiation having a freçuency higher than the microwaverégion of the electromagnetic spectrum, while said portion isuncured and in a State susceptible to having the amount ofnitrosamines reduced or formation of nitrosamines arrested, fora sufficient time to reduce the amount of or substantiallyprevent formation of at least one nitrosamine. 63 01124 U
4. 4. The process according to claim 3, wherein saidsubjecting co radiation is carried out on a tobacco leaf orportion thereof after onset of yellowing in the leaf and priorto substantial accumulation of tobacco-specific nitrosamines in the leaf.
5. 5. The process according to claim 3, wherein saidsubjecting to radiation is carried out prior to substantial lossof the plant's cellular integrity.
6. 6. The process according to claim 3, wherein the tobaccois flue tobacco and said subjecting to radiation is carried outwithin about 24 to about 72 hours post-harvest.
7. 7. The process according to claim 3, wherein saidradiation is applied to the plant for a period of at least aboutone second at a predetermined power ievel.
8. 8. The process according to claim 3, wherein saidsubjecting to radiation prevents normal accumulation of at leastone tobacco-specific nitrosamine in the leaf.
9. 9. The process according to claim 8, wherein said at leastone tobacco-specific nitrosamine is selected from the groupconsisting of N'-nitrosonornicotine, 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N'-nitrosoanatabine and N'-nitrosoanabasine. 10. The process according to claim 4,wherein said subjecting to radiation is carried out on tobaccoleaves arranged in single layer thickness, without stacking orpiling of the leaves.
10. 11. The process according to claim 10, further comprising,prior to said subjecting to radiation, a step of (a) removingstems from the tobacco leaves, (b) pressing the tobacco leaves 69 011240 to remove excess moisture, or (c) subjecting the tobacco leaves to a steam treatment.
11. 12. The process according to claim 3, further comprisingdrying the portion after carrying out the radiation step.
12. 13 . The process according to claim 3, wherein said radiation is generated by a laser beam, 14 . The process according to claim 3, wherein said radiation is an électron beam generated by an électron accelerator. 15. The process according to claim 3, wherein said radiation is gamma radiation.
13. 16. A tobacco product comprising tobacco having a reducedcontent of at least one tobacco-specific nitrosamine, producedby a process comprising subjecting the tobacco, while the tobaccois uncured and susceptible to having formation of said at leastone tobacco-specific nitrosamine arrested, to a concentrated formof radiation having a frequency higher than the micro-wave régionof the electromagnetic spectrum.
14. 17. The tobacco product according to claim 16, wherein saidsubjecting to radiation is carried out on a tobacco leaf orportion thereof after onset of yellowing in the leaf and priorto substantial accumulation of tobacco-specific nitrosamines inthe leaf.
15. 18. The tobacco product according to claim 16, wherein saidsubjecting to radiation is carried out prior to substantial lossof the tobacco's cellular integrity. 70 011240
16. 19. The tobacco product according to claim 17, wherein thetobacco is flue tobacco and said subjecting to radiation iscarried out within about 24 to about 72 hours post-harvest.
17. 20. The tobacco product according to claim 16, wherein saidmicrowave radiation is applied to the plant for a period of atleast about one second at a predetermined power level.
18. 21. The tobacco product according to claim 20, wherein saidsubjecting to radiation prevents normal accumulation of at leastone tobacco-specific nitrosamine in the leaf.
19. 22. The tobacco product according to claim 21, wherein saidat least one tobacco-specific nitrosamine is selected from thegroup consisting of S'-nitrosonornicotine, 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N'-nitrosoanatabine and N'-nitrosoanabasine.
20. 23. The tobacco product according to claim 17, wherein saidsubjecting to radiation is carried out on tobacco leaves arranaedin single layer thickness, without stacking or piling of theleaves.
21. 24. The tobacco product according to claim 23, furthercomprising, prior to said subjecting to radiation, a step of (a)removing stems from the tobacco leaves, (b) pressing the tobaccoleaves to remove excess moisture, or (c) subjecting the tobaccoleaves to a steam treatment.
22. 25. The tobacco product according to claim 16, furthercomprising drying the portion after carrying out the radiationstep.
23. 26. The tobacco product according to claim 16, wherein saidradiation is generated by a laser beam. 71 011240
24. 27. The tobacco product according to claim 16, wherein said radiation is an électron beam generated by an électron accelerator.
25. 28. The tobacco product according to claim 16, wherein said radiation is gamma radiation.
26. 29. A method for reducing the content of at least one tobacco-specific nitrosamine in cured brown tobacco, comprising rehydrating the cured tobacco, and subjecting the rehydrated tobacco to a concentrated form of radiation having a frequency higher than the microwave région of the electromagnetic spectrum, at a predetermined energy level for a predetermined length of time.
27. 30. The method according to claim 29, wherein said rehydrating step comprises adding water to the cured tobacco sothat the tobacco absorbs an amount of water from about 10% byweight up to a maximum absorption capacity.
28. 31. The method according to claim 29, wherein said at least one tobacco-specific nitrosamine is selected from the group consisting of N'-nitrosonornicotine, 4—(N— nitrosomethylamino)-1- (3-pyridyl)-1-butanone, N' - nitrosoanatabine and N'-nitrosoanabasine.
29. 32. A method of manufacturing a tobacco product, comprising subjecting tobacco leaves to a concentrated form of radiation having a frequency higher than the microwave région of the electromagnetic spectrum, while said leaves are uncured 72 011240 and in a state susceptible to having the amount of tobacco- specific nitrosamines reduced or formation of tobacco-specific nitrosamines arrested, for a sufficient time to reduce the amount of or substantially prevent formation of at least one 5 tobacco-specific nitrosamine in the leaves, and forming said tobacco product comprising the irradiated leaves, the tobacco product being selected from the group consisting of cigarettes, cigars, chewing tobacco, snuff and tobacco- containing gum and lozenges. •'"Ίο 33. The process according to claim 32, wherein the leaves are subjected to said radiation after onset of yellowing in theleaves and prior to substantial accumulation of tobacco-specific nitrosamines in the leaves.
30. 34. A tobacco product comprising cured non-green tobacco13 suitable for human consumption and having a collective content of N'-nitrosonornicotine, 4-(N-nitrosomethylamino)-1-(3- pyridyl)-1-butanone, N'-nitrosoanatabine and N’- nitrosoanabasine less than .2 pg/g.
31. 35. The tobacco product according to claim 34, wherein 2u said content is less than about .15 μg/g.
32. 36. The tobacco product according to claim 35, wherein said content is less than about .1 μς/g. 73 01124Û
33. 37. The tobacco product according to claim 34, which is a product selected from the group consisting of cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum and lozenges. 3 38. A tobacco product comprising cured non-green tobacco suitable for human consumption and having a content of N'- nitrosonornicotine which is less than about .15 gg/g.
34. 39. The tobacco product according to claim 38, wherein said content is less than about .1 gg/g. ij 40. The tobacco product according to claim 39, wherein said content is less than about .05 gg/g.
35. 41. The tobacco product according to claim 38, which isa product selected from the group consisting of cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum and 1:. lozenges.
36. 42. A tobacco product comprising cured non-green tobacco, suitable for human consumption and having a content of 4-(N- nitrosomethylamino)-1-(3-pyridyl)-1-butanone which is less than about .002 gg/g.
37. 43. The tobacco product according to claim 42, wherein said content is less than about .001 gg/g.
38. 44. The tobacco product according to claim 43, wherein said content is less than about .0005 gg/g. 7/4 73/1 01124Ü 45. 'The tobacco product according to claim 42, which is a product selected from the group consisting of cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum and lozenges.
39. 46. Cured yellow tobacco suitable for human consumption and having a collective content of N'-nitrosonornicotine, 4- (N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N' - nitrosoanatabine and N'-nitrosoanabasine less than .2 gg/g.
40. 47. Cured yellow tobacco according to claim 46, wherein said content is less than about .15 μg/g. 48 . Cured yellow tobacco according to claim 47, wherein said content is less than about .1 μg/g. 49. Cured yellow tobacco suitable for human consumption and having a content of N’-nitrosonornicotine which is less than about .15 pg/g.
41. 50. Cured yellow tobacco according to claim 49, wherein said content is less than about .1 μg/g.
42. 51. Cured yellow tobacco according to claim 50, wherein said content is less than about .05 pg/g.
43. 52. Cured yellow tobacco suitable for human consumption and having a content of 4-(N-nitrosomethylamino)-1-(3- pyridyl)-1-butanone which is less than about .002 μg/g. 75 73/2 011 2 4 Û
44. 53. Cured yellow tobacco according to claim 52, wherein said content is less than about .001 gg/g.
45. 54. Cured yellow tobacco according to claim 53, wherein said content is less than about .0005 pg/g.
46. 55. A tobacco product comprising cured non-green or yellow tobacco suitable for human consumption and having a content of at least one tobacco-specific nitrosamine selected from the group consisting of N'-nitrosonornicotine,. 4- (N- nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N’- nitrosoanatabine and N'-nitrosoanabasine which is within about 25% by weight of the content of said at least one tobacco- specific nitrosamine in a freshly harvested green tobacco crop from which the non-green or yellow tobacco was made.
47. 56. The tobacco product according to claim 55, wherein said content is within about 10% by weight of the content ofsaid at least one tobacco-specific nitrosamine in said green tobacco.
48. 57. The tobacco product according to claim 56, whereinsaid content is within about 5% by weight of the content ofsaid at least one tobacco-specific nitrosamine in said green tobacco. 71 73/3 Q1 1 2 4 Ο
49. 58. The tobacco product according to claim 55, which is a product selected from the group consisting of cigarettes, cigars, chewing tobacco, snuff and tobacco-containing gum and lozenges. 5 59. A tobacco product comprising cured non-green or yellow tobacco suitable for human consumption and having a content of at least one tobacco-specific nitrosamine selected from the group consisting of N'-nitrosonornicotine, 4-(N- nitrosomethylamino)-1-(3-pyridyl)-1-butanone, N'- 1u nitrosoanatabine and N'-nitrosoanabasine which is at least about 75% by weight lower than the content of said at least one tobacco-specific nitrosamine in cured brown tobacco made from the same tobacco crop from which the non-green or yellowtobacco was made, but which was cured in the absence of steps 1¼ designed to reduce the content of said at least one tobacco- specif ic nitrosamine.
50. 60. The tobacco product according to claim 59, whereinsaid content is at least about 90% by weight lower than the content of said cured brown tobacco. i; 61. The tobacco product according to claim 60, wherein said content is at least about 95% by weight lower than' the content of said cured brown tobacco. 77 73/4 011240 62. ' The tobacco product according to claim 61, which is a product selected from the group consisting of cigarettes,cigars, chewing tobacco, snuff and tobacco-containing gum andlozenges. 7K 73/5