US1962145A - Method of reducing the nicotine content of tobacco - Google Patents

Description

Patented June 12, 1934 METHOD OF REDUCING THE NICOTINE CONTENT OF TOBACCO .Paul Magnus Gross and Lawrence F. Dixon,

Durham, N. 0., assignors, by mesne assignments, to Hall Tobacco Chemical Company, Jersey City, N. J., a. corporation of New Jersey No Drawing. Application March 15, 1933,

Serial No. 660,976

'19 Claims. (Cl. 131-6) Our present invention relates to certain new and useful improvements in processes of reducing the nicotine content of tobacco, whether the latter is in the form of leaves, strips or the manu- 5 factured products, such as cigarettes, cigars,

smoking tobaccos andthe like, and also whether such products have been previously packaged or boxed or not. a

A prime object of the invention is to provide a process of the character stated that may be readily carried out without the employment of expensive or unusual equipment, and wherein the treatment will not only remove or reduce the nicotine content, but will actually improve the tobacco by making it milder, and this is especially true of normally harsh and strong tobaccos.

Another object of the invention is to provide a process that may be readily regulated'so that the amount or quantity of nicotine removed from the tobacco may be controlled-at will, whereby the original nicotine content of selected grades or types of tobaccos having once been determined, may be reduced to any extent desired.

Our invention is based upon the discovery that ethylene oxide, and more particularly ethylene oxide in the form of a gas, when properly applied to tobacco and preferably with due regard to the moisture content of the tobacco, will react chemically with the nicotine therein so as to alter its chemical constituents and thus remove their harmful effects, while at the same time rendering the tobacco milder and smoother, especially for smoking purposes.

One important feature of our invention is that the process may be carried out at ordinary temperatures and in a practical length of time.

Briefly and generally stated, our process includes the steps of placing the tobacco to be treated in a closed receptacle of appropriate size depending upon the. amount to be processed; evacuating or partially evacuating the receptacle, and then introducing into the receptacle a regulated quantity of ethylene oxide gas and permitting the tobacco to remain under the influence of the gas for a predetermined length' of time, de-

pending upon the nicotine reduction, desired, after which the receptacle is opened and the tobacco removed. Obviously the receptacle will be provided with a suitable door having an air-tight closure and a preferred construction would be one wherein the tobacco could be loaded onto trucks that may be easily trundled into and out of the receptacle.

In order to enable others skilled in the art to understand and practice our said invention we will now proceed to describe the same by giving specific examples of some of our experiences, it being understood that they are merely illustrative and not to be taken as restrictive, but before stating the experiences we wish to point out that 6 our process has the great advantageover others 7 in that it does not involve heating the tobacco or subjecting it to the action of solvents or solutions, such as are required by practically all prior methods.

As one example to illustrate the method of treatment we may cite the following: Sixty cigarettes having the correct moisture content necessary for the success of the process were placed in a closed container which was then evacuated to a pressure of 11 mm. of mercury after which the gas ethylene. oxide was admitted to the container until the pressure rose to 371 mm., thus subjecting the cigarettes to a partial pressure oiapproximately one-half an atmosphere of ethylene oxide gas corresponding to a concentration or dosage of the gas equivalent to 55.8 lbs. per 1000 cubic feet. The cigarettes were allowed to remain in contact with the gas for five hours at the end of which time they were removed and analyzed. The cigarettes before treatment had a nicotine content of 2.42% calculated to the dry basis, and after treatment they had a nicotine content of 0.30% on the dry basis thus showing that this treatment greatly reduced the nicotinev content.

The method furthermore possesses the very great advantage that it can be carried out on the finished tobacco products after packing in the packages or containers in which they are usually sold to the consumer, as the gas is able, to penetrate such containers and effectively reduce the nicotine contentot the tobacco, provided only that such containers are not absolutely gas tight as in the case of so-called vacuum tins. Thus packages of cigarettes whose average nicotine content was 2.40% and whose moisture content was correct, which were wrapped, as is commonly done in moisture-proof cellophane wrappers, and sealed, were placed in a container and then the container was evacuated to a low pressure. Ethylene oxide was then admitted to the container until the pressure within it was equal to that of the atmosphere, after which the container was closed oil from the supply of ethylene oxide and the packages were allowed to remain in contact-with the gas for 180 minutes. The container was then opened and the cigarettes in the package were analyzed and found to contain only 0.25% nicotine.

Again a sample consisting of cigarettes weighing 425 grams packed in packages wrapped with moisture-proof cellophane and contained in a carton of the usual type was placed in a container holding 2900 cc. which was then evacuated to a low pressure. Ethylene oxide gas was then admitted to the container in an amount corresponding to a pressure of 0.7 of anatmosphere (concentration of 78.1 lbs. per 1000 cu. ft.) and allowed to remain two and one-half hours. Airrwas then admitted to the container and it was opened and the packages were removed. Analysis of the cigarettes after this treatment showed themto contain 1.30% nicotine as compared with their original nicotine content of 2.59% before such treatment.

We have further treated samples of blended Virginia and Burley tobaccos, containing the proper amount of moisture, in the form known as strips" with the gas ethylene oxide and have reduced their nicotine content from 2.33% before treatment to 0.16% after treatment. This shows that this process of treatment is not dependent on the presence of substances such as sugar or the like which may be present in the finished product but is effective on the unprocessed, redried" tobaccos provided they have the proper moisture content and is the result of the action of the ethylene oxide itself in the presence of the right quantity of moisture and is not caused by the ethylene oxide acting with or through substances other than moisture which may be present in the tobacco in manufactured form as in cigarettes.

A sample of Burley tobacco having the proper moisture content in the form of strips which contained orginally 3.16% of nicotine was treated for three hours in a container with ethylene oxide under atmospheric pressure. After such treatment the tobacco contained only 0.54% of nicotine thus indicating that tobaccos containing large percentages of nicotine can by this treatment have their nicotine content greatly reduced.

This process can also be used to completely remove the nicotine from tobacco. For example cigars containing 0.74% of nicotine and the right amount of moisture were treated with ethylene oxide gas under atmospheric pressure for a period of three hours. On analysis after this treatment the cigars had no detectable nicotine content.

The above illustrations indicate the general scope and character of our process or method. Since our discovery consists not only in the fact that ethylene oxide will reduce the nicotine content of tobacco under the proper conditions, but also includes the discovery of the conditions under which this reduction takes place, we will now detail the" technique we have found necessary for successfully, carrying out the process under certain conditions.

We have discovered that ethylene oxide 'gas will not reduce the nicotine content of tobacco efliciently unless there is the proper amount of moisture present when the tobacco is brought in contact with the gas. The effect of moisture may be seen if we compare the extent of nicotine reduction produced by the same concentration of the gas acting on difierent lots of the same sample of tobacco, each lot being of the same weight but containing varying amounts of moisture.

The untreated sample of tobacco contained 2.57% nicotine (dry basis). The quantity of tobacco usedin each lot corresponded to a charge of 1362 lbs. in a container holding 1000 cubic feet. The concentration of ethylene oxide gas cubic feet or to a partial pressure of about 0.5 atmosphere of the gas. 'The time of exposure was five hpurs for each lot. When the tobacco contained 2.0% to 3.0% of moisture (calculated to the dry basis) only a very slight reduction of nicotine content of from 0.57% to 0.64% was effected. When the tobacco contained 5.4% moisture a reduction of 1.47% was effected in the nicotine content under the same conditions. With a moisture content of 8.8% in the tobacco a reduction in nicotine content of 2.15% was effected. With increasing moisture content in the tobacco above 8.8% the extent of the reduction of nicotine increased very gradually above a reduction of 2.15% in nicotine until with a moisture content of 14.5% in the tobacco a nicotine reduction of 2.3% was effected by treatments under the same conditions as above. After this reduction of 2.3% in the nicotine content of the tobacco sample containing 14.5% moisture there remained only a residual nicotine content of 0.27% in the tobacco sample. (The moisture contents here referred to were those found by determining the per centloss in weight, calculated on the weight of dry tobacco, of samples of tobacco when these were placed over 95% sulphuric acid in desiccators for a period of seven days at a constant temperature of 30 C.)

The above treatments show that to effectively 7 reduce the nicotine content of tobacco by the use of ethylene oxide it is necessary to have a moisture content of at least 8% in the tobacco. As numerous trials similar to those above have shown us that the presence of the properamount of moisture is required for the successful carrying out of this process we wish to emphasize this necessary feature of our process or method.

We have also discovered that it is possible to control the extent of the nicotine reduction and yet carry out the process efliciently provided the proper moisture content is present by variation in the concentration or dosage of the ethylene oxide gas, by variation of the duration of exposure of the tobacco to the gas and by variation of the charge of tobacco used in a container. Since too large a reduction in the nicotine content may alter the taste of the tobacco or tobacco product it is important to be able to control exactly the extent of such reduction. This we have been able to do by variation of the factors just cited as affecting the extent of reduc tion. While in practice it may be desirable to vary more than one of these factors at a time, we will here describe the effect of the variation of each one separately for the sake of clarity. The cases we will cite and the actual quantities involved are by way of illustration and are not to be construed as limiting the application of the process to these quantities or limits.

We will consider the effect of varying concentration or dosage of the gas ethylene oxide first, the time of exposure and the amount of tobacco being fixed. A quantity of tobacco in the form of cigarettes of the proper moisture content; namely, 10%, was divided into equal lots each of whose weights corresponded to a charge of 8,170 lbs. of tobacco per 1000 cubic feet of container space. Each of these lots were treated with a different concentration of ethylene oxide gas for the same period of time-2V hours. The original untreated tobacco had a nicotine content of 2.59%. The first lot of tobacco was treated with a concentration of ethylene oxide of 22.3 lbs. per 1000 cubic feet and showed a nicotine reduction of 0.48%. The second lot wastreated untreated cigarettes.

- witha concentration of ethylene oxide gas corresponding to 33.5 lbs. per 1000 cubic feet and a nicotine reduction of 0.70% resulted. The lot treated with a concentration of ethylene oxide gas of 44.6 lbs. per 1000 cubic feet showed a nicotine reduction of 0.98%. The cigarettes from these three lots were found to have good aroma and taste on smoking when the standard of comparison was the aroma and taste of the original untreated cigarettes. A fourth lot was treated with a concentration'of ethylene oxide gas of 55.8 lbs. per 1000 cubic feet and showed a nicotine reduction of 1.07%. A fifth lot was treated with a concentration of 78.1 lbs. per 1000 cubic feet and a nicotine reduction of 1.29% resulted. The aroma and taste of the cigarettes of these fourth, and fifth lots was good but differed slightly, in character from' that of the original These cases show that it is possible to control the extent of nicotine reduction by varying the concentration of ethylene oxide gas used.

We will next show how the duration of exposure of the tobacco to the gas affects the nico-' tine reduction. A quantity of cigarettes having a proper moisture content; namely, 10%, and corresponding to a charge of 643 lbs. of tobacco per 1000 cubic feet of container space was treated with a concentration of ethylene oxide gas corresponding to 55.8 lbs. per 1000 cubic feet. From the rate at which the gas was absorbed and from determination of the nicotinecontent of similar lots of cigarettes exposed to this concentration of the gas for varying lengths of time the extent of the reduction in the nicotine content of these cigarettes was determined at different times of exposure to be as follows: after hour, 0.78%; after 1 hour, 1.33%; after 2 hours, 1.72%; after 2 ,4; hours, 1.88%; after 3 hours, 2.00%; after 4 hours, 2.27%; and after 5 hours, 2.47%. The nicotine content of. the cigarettes had therefore been reduced to 0.12% after five hours exposure. Thus by control of time of exposure of the to bacco to the gas it is possible to produce any desired nicotine content provided suflicient quantities of gas are employed and the tobacco has the proper moisture content.

The third factor by variation of which it is possible to change the extent of the nicotine reduction in practice is the quantity of tobacco or charge used in relation to the size of the container employed for treatment with the gas, and in relation: to the times of exposure used and the gas concentrations employed. we have shown with tobacco of a proper moisture content of 10.0% that if a constant time of five hours of exposure to the gas ethylene oxide was used and a constant concentration of 55.8 lbs. per 1000 cubic feet with varying amounts ofcharge per 1000 cubic feet of container space the following nicotine reductions resulted: With a charge corresponding to 318 lbs. per 1000 cubic feet a reduction of 2.35% in nicotine content; with a charge of 2591'lbs. a reduction of 1.86%; with a charge of 3402 lbs. a reduction of 1.75%; and with a charge of 8397 lbs. a reduction of 1.06%.

By the variation of the above three factors either independently or concurrently we have been'able to reduce the nicotine content of tobaccos containing widely different amounts of nicotine to any desired extent.

We have further found that the extent of the reductionin the nicotine content of tobacco may be controlled and even checked by the admixture with the ethylene oxide gas of various amounts of carbon dioxide or other-gases. Thus packages of cigaretteis with a correct moisture content wrapped in cellophane were subjected to the action of a mixture of carbon dioxide and ethylene oxide for a period of five hours. This mixture consisted of two parts of ethylene oxide gas and eight parts of carbon dioxide gas and was placed in a closed'container with the cigarettes so that the total gas pressure due to these two gases withinthe container was'equal to that of the atmosphere which was 749 mm. pressure. This amount of ethylene oxide-corresponds to a concentration of approximately 22.3 lbs. per 1000 cubic feet of container space. This treatment in the presence of carbon dioxide caused a reduction of the nicotine content of the cigarettes of 0.67%. Under similar conditions ethylene oxide gas alone in the absence of carbon dioxide gas at the same concentration of 22.3 lbs. per 1000 cubic feet produced a nicotine reduction in cigarettes of the .proper moisture content of 1.42%. I

In these cases the nicotine reduction effected by the ethylene oxide gas alone was shown to be twice as great as that when it was mixed with carbon dioxide. We have furthermore shown by numbers of trials of this type that if the propor-" tion of carbon dioxide in the mixture is increased relative to the amount of ethylene oxide in it, the eifectiveness of ethylene oxide present is very .much less than if it were present in the same amount in the container without the carbon dioxide present. Similar results have been found by us to hold true for mixtures of ethylene oxide and air.

We are familiar with the fact that it has been proposed experimentally to employ ethylene oxide gas and its mixtures with carbon dioxide and air as an insecticide to eradicate beetles and other insects in .various materials among which was tobacco. The dosages or concentrations when used as such an insecticide correspond to concentrations of from 1 to 2 lbs. of ethylene oxide gas per 1000 cubic feet of space. We wish to stress the fact that these concentrations are far below those which we have found necessary and the other conditions in such operations are totally inadequate to produce even slight nicotine reductions. Treatment of tobacco with amounts of ethylene oxide as small as those used when it is employed as an insecticide will not produce any detectable reduction in nicotine content.

In order to show that the treatment of tobacco I with ethylene oxide reduces the nicotine content of the tobacco smoke from such tobacco as well as that of the tobacco itself; a comparison of the cigarettes were smoked in a specially constructed automatic smoking apparatus under standard and previously defined and-control'ed conditions. The smoking procedure was identical in every respect for the untreated and treated cigarettes and was intermittent and in close imitation of the smoking as ordinarily done by a smoker. All of these products of the. combustion which would ordinarily enter'the smokers mouth were aspirated or drawn through a glass tube fitted with electrodes, in which tube theywere precipitated by a miniature Cottrell precipitator according to a well standardized technique which had previously been worked out for such analyses of tobacco smoke. In this way the nicotine in the smoke was precipitated inthe glass tube and the nicotine content of the tube and therefore that of the smoke was determined, using a modified silico-tungstate method for the analysis which had previously been shown to be accurate for the quantities of nicotine obtained in this way on smoking cigarettes in the smoking apparatus.

By'this procedure it was found that the smoke from the cigarettes which had been treated with the ethylene oxide gas in the above amounts contained on the average only 25% as much nicotine as the smoke from the cigarettes which had not been treated. This shows that this treatment greatly reduces the amount of nicotine present in p the smoke from tobaccos which have been so processed. 1

In order to show that this treatment not only reduces the nicotine content of the tobacco as shown by chemical analysis but also produces a proportionate decrease in the physiological activity of the smoke of the tobacco we have carried out tests of the effect of smoke from untreated and treated tobaccos on the contraction of leech muscles. These tests were carried out according to the well recognized procedure and technique described by Winterstein and Aronson which is regarded as the best and most accurate quantitative measure of the physiological effect of varying amounts of nicotine. Description of the method of carrying out such tests will be found in three articles by Alfred Winterstein and Ernst Aronson published in the Zeitschrift fiir Hygiene and Infectionskrankheiten, volume 107, page 487 in 1927, volume 108, pages 530 to 533 in 1928 and volume 110, pages 644 to 653 in 1929. We. used these methods in making the tests on treated and untreated cigarettes. Smoke from cigarettes which had not been treated with ethylene oxide was caught in tubes as previously described and compared with the smoke from cigarettes which had been treated with ethylene oxide using'the physiological test just described. It was thus found that the physiological activity due to nicotine of the smoke from untreated cigarettes was from three to four times greater than that of the smoke from cigarettes which had been treated with ethylene oxide gas by our process. It is thus clear that this process of treatment with ethylene oxide not only reduces the nicotine content of tobaccos as shown by chemical analysis but also renders the nicotine physiologically inactive probably by combiningit with the ethylene oxide in the presence; of moisture to form a new physiologicaly inactive compound. This is further borne out by certain tests which we have made on nicotine solutions instead of tobacco. A nicotine tartrate solution was tested by means of the leech,muscle in a concentration corresponding to 0.0020 grams of nicotine per liter of solution and found to cause a vigorous contraction of the leech muscle. A water solution of nicotine was treated with ethylene oxide and was then purified and freed from ethylene oxide. This solution when used in a concentration corresponding to 0.0024 grams per liter (figured on its original nicotine content before treatment),

caused no contraction of the leech muscle. 'This shows that the ethylene oxide in the presence of moisture combines with the nicotine toform a new .compound which is not physiologically active as is the nicotine.

We have also tried action of higher homologs or derivatives of ethvlene oxide and found that ing or removing their harshness of strength without impairment of their desirable natural taste; Such improvement is effected by subjecting the tobacco, either in the form of leaf or strip, or as the manufactured product such as cigarettes, cigars, or smoking tobaccos, to the action of the gas ethylene oxide for predetermined lengths of time, the gas being used in such amountsand under such pressures as may be necessary for the particular type of tobacco in question.

Particularly is this treatment effective in the case of strong or heavy tobaccos which would ordinarily be regarded as strong for ordinary smoking purposes. As an example of the application of this process the following is cited. Ten cigars weighing grams, of a strong type and containing the proper percentage of moisture were placed in a container which was then evacuated. Ethylene oxide gas was then admitted to the container until the pressure within it was equal to that of the atmosphere. The cigars were allowed to stand in contact with the gas in the container for three hours and then removed. On smoking, these cigars showed a remarkable improvement, becoming very much milder, yet without having their taste and aroma impaired. Analyses of samples of these cigars before this treatment showed them to contain 0.74% of which contained a high nicotine'content; namely, 3.15%, were subjected to the action of the gas ethylene oxide for a period of'three hours under conditions similar to those outlined above for the cigars. After such treatment the nicotine content of these cigarettes was reduced to 0.37% and there was a tremendous improvement in the quality of the smoke from them, which was mild and smooth in contrast to the harshness and irritation noticeable in the smoke of the original untreated cigarettes.

We have furthermore found it possible to reduce the harshness of a blended tobacco product by treating by this process, before blending into the finished product, those tobaccos which cause such harsh or objectionable character as the product may possess and then carrying out the blending subsequent to such treatment. Thus for example a cigarette blended from Virginia and Burley types of tobaccos may have its smoking quality improved and any harshness eliminated by treating the Bm-ley portion of its ingredients with ethylene oxide gas in proper amount, and for the proper length of time before such Burley portion is incorporated in the finished blend in the usual course of manufacture.

We have also found that it is possible to reduce the nicotine content of tobacco by treating it with a solutionof ethylene oxide or its homologs. Thus ethylene oxide may be dissolved in water and the water solution may be applied to the tobacco either by spraying or sprinkling, or the tobacco may be immersed or dipped in the solution containing the ethylene oxide. Thus for example a water solution containing 5 per cent by weight of ethylene oxide when sprayed on tobacco reduced the nicotine content of the tobacco from 2.8% originally present to 2.1% after treatment. This action is not confined to water solutions but isalso shown by other solutions of ethylene oxide.

We have furthermore round that this process of treatment of tobacco with ethylene oxide reduces the acidity of tobacco as shown by determination of the water soluble acidity of the tobacco and also by determination or the socalled pH or Sorsensen value representing the hydrogen ion concentration or the aqueous tobacco extract. Thusthis process is effective in reducing the acid content 01 tobaccos,- without however, making them alkaline.

What we claim and desire to secure by Letters Patent is:-

1. The process of reducing the nicotine content of tobacco, which consists in subjecting tobacco having a predetermined moisture content to the action of gas ethylene oxide.

2. The process of reducing the nicotine content of manufactured tobacco products such as cigarettes, cigars, smoking or chewing tobacco in packages, cartons, or unsealed tins, such as are usually employed in marketing such products, and wherein the products have a predetermined moisture content, which consists in subjecting the packaged products to the gas ethylene oxide.

3. The method of de-nicotinizing tobacco,

which consists in subjecting the-tobacco to the action 01 ethylene oxide gas in thepresence 01' a predetermined quantity 0! moisture.

4. The method of reducing the nicotine content of tobacco, which consists in enclosing the tobacco within a closed receptacle and then subjecting the tobacco so enclosed to the action of ethylene oxide gas admitted into the receptacle.

5. The method of reducing the nicotine conminedperiodoitime. 7. A method of reducing'the nicotine content of tobacco, which consists-in enclosing tobacco within a closed chamber, partially evacuating the chamber, then admitting ethylene oxide gas into the chamber and permitting the tobacco to remain under the influenced! the gastor a predetermined length 01' time dependent upon the extent of nicotine reduction desired.

8. The method o1 reducing the nicotine vcontent of packaged tobacco products, which consists in enclosing packages of such products within a closed chamber, partially evacuating the her, then introducing ethylene oxide gas into said chamber at a predetermined pressure and permitting the tobacco products to remain under the influence of the gas for a predetermined length of time.

9. A method of reducing the nicotine content of tobacco having a moisture content of approximately 8%,which consists in enclosing such tobacco within a closed chamber, exhausting air from such chamber and then introducing into the chamber ethylene oxide gas under'a predetermined pi'essure and permitting the tobacco to remain in the chamber under the influence of such gas for a predetermined length of time.

10. A method of treating strong or irritating 9Q tobaccos to render them mild and non-irritating, which consists in subjecting the tobaccos to the action of ethylene oxide gas in the presence of a predetermined quantity of moisture and for a tent of tobacco, which consists in subjecting tobacco having a predetermined moisture content,'to the action of ethylene oxide gas andin regulating the concentration of the gas to control the said reduction. 1 13. The method of reducing the nicotine con.- tent of tobacco, which consists in subjecting tobacco having a predetermined moisture content,

to the action of ethylene oxide gas and in regulating the pressure of the gas and the length of the treatment to control the said reduction.

14. The method of reducing the nicotine content oi! tobacco, which consists in treating the tobacco with a dilute. solution of ethylene oxide.

15. The method of reducing the nicotine con- 1. 0 tent of tobacco, which consists in spraying the tobacco with a dilute solution of ethylene oxide.

16. The method of reducing the nicotine content of tobaccos, which includes treating the tobaccos with solutions containing an ethylene oxide linkage.

17. The method of reducing the acidity of tobacco mixtures, which consists in treating such mixtures with ethylene oxide in the presence or a predetermined amount of moisture. 330 18. The method of reducing the physiological. activity of the smoke of tobacco, which consists in treatingwtobacco having a predetermined moisture content with ethylene oxide.

19. The method of reducing the nicotine con- 1 35 tent of tobacco, which consists in enclosing the tobacco within a closed container, introducing ethylene oxide gasinto the container, and regulating the concentration 01 the gas proportionate to the weight of the tobacco being treated in the 14;) container to control the extent to which the nicotine content is reduced.

-, PAUL MAGNUS GROSS.

LAWRENCE F. DIXON.