US2914072A - Process of improving the smoking qualities of tobacco - Google Patents

Description

14,072 j PRoCESSoF'MPROVING THE SMOKING QUALITIES F TOBACCO Daniel Tyrer, Devon, England, and Denis D. Tyrer,

. 0 1 College Park, Md.

I No Drawing. Application January 31, 1955 Serial No. 487,462

2 Claims. (Cl. 131140) This invention relates to processes of improving the smoking qualities of tobaccos. The quality of tobacco depends upon many factors. In the broadest meaning of the term there is included aroma or smell (both of the tobacco itself and its smoke), color, texture, ashiness, combustibility, as well as strength or its opposite mildness. In the present invention we are concerned only withthose factors which determine strength or mildness .As is well known tobacco contains the alkaloid nicotine; and Whilst nicotine is an essential ingredient of all tobaccos it is true that if a particular tobacco is rela tively rich in nicotine that tobacco will be physiologically strong in smoking. But it does not necessarily follow fromlthis that a tobacco low in nicotine is necessarily mild. Other factors besides nicotine are involved in the determination of the smoking quality of a tobacco.

It is generally agreed that flue-cured tobacco owes its distinctive quality largely to its high sugar content though other factors undoubtedly enter into the matter.

It is known that the mineral constituents play an important part in determining combustibility. In this respect potassium and magnesium are beneficial whilst chlo- I rine is distinctly harmful.

But it is the nitrogen compounds present in all tobaccos which play the most important role in determining quality and tobacco technologists are generally agreed ascribing rankness fiin a tobacco to "a high protein content.

Now it will be generally agreed that in studying the problem of. tobacco quality too much reliance cannot be placed on ones personal reaction in smoking. Whilst all smokers might agree in describing one particular tobacco as very strong or rank and another as very mild, opinions would differ about intermediate qualities. To

a dry basis.

Approximate Nicotine Smoke Price of Tobacco, British U.S. Equiv- Content, Alkalinity currency, pence per oz. alent, cents percent (5A.)

. per oz.

-.63 74 2. 52 3. 3 52.- 61 4. 05 3. 0 49.5 58 3.63 3. 5 47 55 2.90 4.2 45.5 53 4. 35 4. 4 44-- 52 4.54 5.5 42.5"; 50 4. 62 7. 0 English grown, low qual V 0.90 9. 8

Additional samples of tobacco were tested as set forth below:

Nicotine Smoke. Ifrlce of Tobacco Content, Alkalinity 1 percent 40 cents per 1% oz 1.79 3:9 30 cents per 1% oz 1. 28 1 53, 9 25 cents per 1% oz 1.33 4. 8 2 15 cents per 1% oz I I 1. 24 1 5. 2--- 11 cents per 1% oz n 1 35 t 7. 0 Very low quality 1. 65 11. 4 .D j 2.07 12.2

gchajsed and branded tobaccos-onesample of very po get over this difliculty we have had resort to the chemical analysis oftobacco smoke rather than to the analysis of the tobacco. itself. It is obvious that it is the smoke enteri ng tlie smokers mouth whichdetermines whether a tobacco is mildand pleasing or strong and disagreeable.

ln thisiconnection tobacco technologists have noticed.v

that the smoke ofa bad quality tobacco has a relatively highs alkaline. reactionwhereas a good .tobacco gives a smoke of low alkalinity. The alkalinity of the smoke is due to ammonia, nicotine and other nitrogen bases derived fr'omithe' nitrogen compounds in the tobacco which undergo pyrolysisv during smoking. The pyrolysis of the porized during smoking.) In the case of cigarette smoking it'has been found by one observer that about 20-25% of the-nicotine in the tobacco enters themouth pantly =asp,1th e-;fre e base and partly combined with acids in thesrnoke;particles; about is thermally destroyed while some 20% escapes into the air in the smoke rising from; the burning tippof the cigarette whilst a few percent 7 but? it definite enoughxto iustifyjaking the smoke; 5 alkalinityas an approximate index of quality. This per-I.

,, mouth.

Patented Nov. 24, 1959.

. 2 i are condensed in the stub. 'It should be mentioned, how-. ever, that other published data on this distribution of nicotine differ fairly'widely from these figures. In tests we have carried out with pipe smoking it was found that 70-80% of the nicotine passes into the smokers Reverting to the question of how .far the determinable alkalinity of the smoke can betaken as a reliable guide or index of tobacco quality we have endeavored to answer the question by purchasing a range of tobaceos,'from the dearest to the. cheapest, and. relating the price to the smoke alkalinity as determined under standardized conditions. W

The results are given in the following table. The smoke alkalinity (-S.A.) is expressed in terms of cubic centimetres of N/ 10 acid required for neutralizing the time bases in the smokev from 1 gram of tobacco of a standard 12% moisture content. The table also givesv the determined nicotine content of the tobacco reckoned onv The results given-in the'table s'are the averagesfof a' number f sj ni eachi ase In a i n t0 'tb p quality, English grown'andeureu tobacco, is listed.

seen that it: bears; no relationship to the .nicotine content of the tobacco. fI'his is. brought ou't. very; clearly by the i L a homergrownsample. which contained. only, 9.90% of 2 'et proved to; be very .disagreeableioni.

nicotine j and smokingr.

0nthe--o,ther handfthere i's .a clear parallelism betweeni the priceand the smoke .alkalinity.l;: 1L

Anexact parallelism;..could not; of course,;be eirpected' mits quality to bejre'xpressed by an. experimentalrfig'ure.

Research onthezproblem of improvinglthe quality oftobacco thus became a matter of treating thetmaterialin various ways or of making various additions to: itwan'd. th'en'determiningthe" eifection the smokesalkalinityr 't".

Before. detailing "thef'results bf special .treatmen'tscit' q i y which is combined w th zo ean ea dm iefiv acetic and formic). closely parallel with the free bases buttfor the sake of s m lets e swe have. in. ll u e paimeptssetetm n d These combined bases generally run 1 both the smoke alkalinity and the total smoke bases which, in what follows, we indicate as T.S.B.

At this stage, also, it will be useful to give some account of what is.already known in tobacco technology for improving the quality and at the same time checking the methods by smoke analyses. Such known treatments are as follows:

(1) Simple heating of tobacco is known to be beneficial and no doubt this is another reason why flue-cured tobacco is usually of good quality for in the flue-curing process the tobacco is heated to 90 C. or over. We have checked this procedure using air-cured tobacco. The following results are an example.

S.A. T.S.B.

Before heating 7. 4 9. 2 After 1 hour's heating at 100 6 1 (2) It is known that the addition of some form of sugar to air-cured tobacco makes an appreciable improvement. Our own tests on the point show that the addition of sucrose has little or no effect (beyond a dilution effect) but that invert sugar is appreciably beneficial. Some results are as follows:

S.A. T.S.B.

Untreated tobacco 1019 13.5 After incorporation 10% sucrose 10:0 11.0 After incorporation 10% invert. sug 8. 10.6 A lter incorporation 15% invert. sug 8. 4 10. 4 After incorporation 20% invert. sug... 8. 3 10.3

Tobacco and acid treatment S.A. T.S.B.

Untreated tobacco of low acidity 10. 9 12. 9 Same treated with 2% phosploric 10. 2 12. 1 Same treated with 4% tartaric 8.9 11.0 Same treated with 3% glycollic-. 9. 5 11.4 Same treated with 3.7% lactic 9. 8 11.9

(4) A good deal of work has been done on reducing the nicotine content of tobacco presumably in'the belief that a strong tobacco could be rendered mild and pleasing simplyby removing the greater portion of the nicotine.

This process of de-nicotinising has generally taken the form of subjecting the heated tobacco to a mixture of steam and ammonia when this latter base replaces some of. the nicotine. One experimental example will illustrate the point. A very strong tobacco containing 5.15% nicotine and giving a S.A. of 10.9 was treated to reduce the nicotine to 2.1%. The S.A. of the product was 9.2only a small reduction (considering the big drop in nicotine content) and still leaving the tobacco strong and unpleasant.

Our own researches on the problem have been directed towards the promotion of a greater degree of thermal destruction of the nitrogen bases during the combustion of tobacco du ring actual smoking, thus reducing the alkalinity of the smoke.

The results of our investigations are summarized as follows: 7 i

(1) Primary catalysts.-We have discovered that small additions'of the salts of certain metals have a marked catalytic effect. These, which we call primary catalysts, include salts of cobalt, manganese, nickel, copper, chromium and silver. Of these the salts of manganese and cobalt are the most effective.

The salts may be of almost any acid with certain reservations. Chlorides are effective but have the disadvantage of tending to spoil the combustibility though, if the tobacco is already too fast burning, this disadvantage disappears.

Generally, it is preferable for the salts to be soluble in water for then thorough incorporation into the tobacco is more easily eifected. However, it is not impossible to use finely divided solids such as oxides and hydroxides, carbonates, phosphates. It has been found that the catalytic effect of the metal is enhanced when the acid associated with it is slightly volatile or can form a volatile acid on pyrolysis for then a part of the remaining nitrogen bases in the smoke are neutralized.

The one type of salt which appear to be definitely disadvantageous are sulphates. This is probably because they are reduced to sulphides which are not efiective as catalysts.

The amount of catalyst required depends, to some extent, on the tobacco and on the degree of amelioration required. With some tobaccos 0.5% of the metal salt is sufiicient but with others 2 or 3% is necessary to give a satisfactory result.

There is some evidence for a theory that sulphur compounds in the tobacco tend to poison the catalyst. (Tobaccos may contain'as much as 1% of sulphur in the form of sulphates and organic sulphur compounds); and when the sulphur content is low a relatively small percentage of catalyst is satisfactory and vice versa.

(2) Secondary catalys!s.We have also discovered that certain other salts which, on general chemical grounds would not be expected to behave as catalysts, do

in fact promote some decomposition of the nitrogen bases and in particular appear to increase the activity ofthe primary catalysts. These substances which we have called secondary catalysts include salts of potassium, magnesium, barium and sodium-they are in this order of effectiveness.

A possible theory to explain their effect is that on heating they form strong bases which can fix some of the I sulphur thus reducing the catalyst poisoning effect of this element. And the reason why they show some effect alone (i.e. without added primary catalysts) is that they permit the normal mineral matter of the ashof the tobacco to bemore effective in decomposing the nitrogen bases. (Tobacco ash contains appreciable amounts of manganese as well as much iron.)

As with the primary catalysts any salt of the above metals will serve (sulphate excepted) but those of organic acids are preferred. The amount to be used again depends upon the tobacco and upon the extent of amelioration desired but in an average case 2% is satisfactory.

These secondary catalysts may be used alone but in general they are best used as promoters of the primary catalysts.

(3) Acids.We have further discovered that both primary and secondary catalysts are more effective if the tobacco is appreciably acidic. Accordingly, when this is not the case, it is advantageous to introduce with the catalysts a suitable proportion of an acid. Any acid except sulphuric will serve the purpose but the preferred acids are the simpler aliphatic acids as listed previously.

neutralization in the smoke resulting from the pyrolysis of one gram of tobacco.

Prior to a chemical analysis of thesmoke, a-smokewast-a.

solution is made, by dissolving the products derived from the pyrolysis of tobacco in a known volume of The total smoke bases consistof the free bases (smoke alkalinity) and the combined bases. In order to. deter mine the total smoke bases it is necessary first to distil the smoke solution under alkaline conditions whereby.

the combined bases are released and are collected together with the free bases in anexcess known volume of 0.1N acid. The distillate is then back-titrated with 0.1N

(4) Sugafs.In the case of an air-cured tobacco which contains little or no natural sugar wehave found that the addition of a suitable sugar. enhances the'effect of the catalysts. With flue-cured tobacco addition of sugar makes no difference. I i

The sugar used should be one rich in laevulose which appears to be more. effective than dextrose and much superior to sucrose; As; however,a pure laevulose is not cheaply available there maybe used, with satisfactory results, sugars consistingof a mixture of dextrose and laevulose such, for example, as invert sugar, uncrystallisable syrups, molasses, honey. q

The amount used may be as much as. 20% but we find is generally adequate.

v THE FINAL MIXTURE 3 Although individual catalytic substances may. be used" in particular'cases' th'e treatmefirin the general case will be with a mixture. The, final-mixture of substances to be used to give the highest amelioration depends upon the character of the tobacco to be' treated. An initial analysisof the'tobacco 'With Qrespect to sugarcontent, nicotine content, total nitrogen, ash, would affordsome guidance but only by a cumbersome method of trial and error could the optimum mixture .be determined. A determination ofthe smoke alkalinity would. provide some indication on the-concentration of the catalyst. mixture to be applied; However, it is possible to generalise and to give a formula which will serve in most cases. The recommended formula is 2% primary catalyst+2% secondary catalyst+l% free acid+8% invert sugar.

The percentages are on the tobacco and refer to the weights of the metal salts reckoned anhydrous.

In practically all cases the above general formula will give a considerable amelioration of a strong tobacco; in some cases it may be found that the tobacco has been rendered too mild in which case the simple remedy is to mix or blend some untreated tobacco with the treated product.

METHOD OF TREATMENT As previously indicated it may sometimes be possible to apply the catalyst mixture as a fine powder when it can be dusted on the slightly moist tobacco as evenly as possible.

But in general it is more satisfactory to apply the mixture in the form of an aqueous solution (or sometimes as a suspension). In this form it may be applied either to uncut tobacco leaf or to cut and shredded tobacco.

If the treatment is applied to leaf the procedure is as follows:

The leaves should be just soft enough to be flattened out when they are sprayed with a solution of the mixture to be applied thesolution being up toabout 40 partsby weight to .1 00, parts of the tobacco and containing the. catalytic substances and any other substance it may be: desired to apply eitherin a v state of solutionoras an' aqueous suspension. They are, then allowed to stand in a'pile for several hours to allow the solution to soak inafter which they are stripped (the midribs removed),

pressed eut and finallydried to-the desired extent. The suitably driedp'rodfuc't may be stored for ageing.

1Q In'applying the treatmentto-tobacco already cut and shredded the solution. is sprayed on to a weighed quantity which is constantly stirred so as to spread the wetting as uniformly as possible; The solution and its concentration should be so adjusted that the final wet material does not contain more than 45% of water and preferably between and After the spraying the moist material should be gathered into a ball or lump or otherwisepressedinto a mass which is allowed to stand for severalhours.v The mass isthen tested out and suitably 2t) dried. Thedrying is preferably done at a fairly low tem- "perature; When dry. i t may be suitably heated as re- If the; tobacco was already heated and aged'the treated product quiredjand may finally be stored for ageing.

may be regarded as fit fonimmediate smoking.

I Examples '(l) "A heated andagedtobacco which had originally been airrcured, in cut and shredded form, was found to contain an 1.63% nicotine but was disagreeable on, smoking. On testing the smoke it was found to be alkalii etoan extentfequivalentjo 8.7 cc. of N/ 10 acid per gram of 1 2% moisture tobacco (S.A.) and to conrain total smoke bases, equivalent to 10.7 cc. of N/IO 35 100 parts of this tobacco were thoroughly moistened with a solution containing invert sugar and cobalt acetate in such amount asto' incorporate into the tobacco 10% of theforrner and 2% of the latter, all quantities being calculated on a dry basis.

40 After drying the product gave smoke tests of 3.8 S.A.

arid 6.0 T.S.B. representing a degree of mildness which was found to; conform; with the personal reaction on smoking j 1 -(2)"A very strong, slightly alkaline, air-cured tobacco containing 5.5% of nicotine and. giving smoke tests of 11.1 S.A. and 14.7 T.S.B. waswetted'with a solution of invert sugar, phosphoric acid and manganese nitrate in such proportions as to incorporate'intothe tobacco 20% invert sugar, 2%1phosphoric acidand 15% manganese nitrate.""The dried. Product gave smoke tests of 578A. and 7.7 T.S.B.:thd was found to be satisfactory on smoking.

(3) A freshly sun-cured tobacco in the form of leaf was sampled and found to contain 5.6% nicotine and to give smoke tests of 6.6 S.A. and 9.0 T.S.B. The nearly dry leaves were thoroughly sprayed with a solution containing potassium acetate, acetic acid and copper acetate, the proportions of the first two being such as to form potassium hydrogen acetate. The composition of the mixed solution and the amount used was such as was calculated to incorporate into the tobacco 2% of potas sium acetate and 2% of copper acetate. After some hours standing the tobacco was stripped, pressed, cut and dried. The dry material was finally heated for 1 hour at 100 C. It was then tested and found to give smoke incorporated instead of 2% copper acetate.

product gave smoke tests of 1.4 S.A. and 5.1 T.S.B..

This product was found to be too mild for enjoyable smoking and was accordingly mixed with an equal amount of the untreated tobacco. The mixture still showed the low smoke tests of 3.0 S.A. and 5.6 T.S.B.

A strong tobacco which had been flue-cured contained 5.9% 'nicotine and "gave'fsmoke tests of 7.4 S:A. and 9.0 T.S.B.

Into it was incorporated 2% magnesium acetate, 1.6% acetic acid and 2% cobalt acetate. The product gave the very satisfactory smoke tests of 2.3 S.A. and 4.95 T.S.B.

(6) A solution containing 4 parts of potassium permanganate in 100 parts of water was added slowly, in the cold, to a solution containing 8 parts of lactic acid in 60 parts of water. After standing some hours the muddy solution was warmed to 70 C. when the suspended manganese dioxide gradually dissolved yielding, finally, a clear solution containing manganese and potassium pyruvates together with some unox'idised lactic acid. The latter was approximately neutralized with potassium carbonate. This solution was then incorporated into an aged tobacco which contained 3.75% nicotine and gave smoke tests of 8.5 S.A. and 11.7 T.S.B. The proportions used were such as to have in the tobacco 3% ofmanganese pyruvate with 2.5% mixed potassium pyruvate and lactate. The product gave smoke tests of 5.2 S.A. and 7.9 T.S.B.

(7) A shag tobacco in shredded form was tested and found to contain 4.4% nicotine and to give smoke tests of 7.0 S.A. and 10.2 T.S.B. The latter figure on further analysis was found to be made up of ammonia and easily volatile amines 7.04, nicotine 2.50 and pyridine-like bases 0.66.

This tobacco was then treated so as to incorporate into it 2% cobalt acetate, 2% magnesium acetate and 1% acetic acid. The product gave smoke tests of 1.4 S.A. and 5.0 T.S.B. the latter being divisible into ammonia bases 3.64, nicotine 0.96 and pyridine bases 0.40. The product was found to be very mild on smoking. a

(8) Some flue-cured tobacco of a high stalk position was found to contain 4.4% nicotine and showed a S.A of 9.9 and T.S.B. 13%. This tobacco was impossibly rank for smoking as such.

The leaves were sprayed with a solution containing invert sugar and magnesium acetate with precipitated manganese carbonate in suspension. The quantities used were such as to incorporate into the tobacco 8% of invert sugar, 2.0% magnesium acetate and 2.5% manganese carbonate. The finished product gave the very satisfactory tests of S.A. 3.0 and T.S.B. 8.5 and was found to be agreeably mild on smoking.

An American air-cured tobacco consisting of upper leaf (tips) was found to contain 1.65% nicotine and gave smoke tests of 11.4 S.A. and 15.4 T.S.B.

The'leaves were sprayed with a solution of invert sugar and cobalt(ous) acetate. 'The quantities used were such as to incorporate into. the tobacco 10% invert sugar and 2% cobalt(ous) acetate. The resulting product gave smoke tests of 5.3' S.A. and 8.9 T.S.B. A considerable improvement in quality was observed on smoking the product. A

. Obviously, modifications in the above described processes may be made without departing from the spirit and scope of this invention, as defined in the appended claims.

Whatis claimed is:

1. The process of treating normally discardable and poor quality portions of tobacco leaves to produce useful cigarette and pipe tobacco of high quality, comprising dispersing in said portions not more than approximately 2% by-weight of a primary catalyst consisting of at least one suitable salt selected from the group of salts of the metals consisting of salts of cobalt, manganese, nickel, copper, chromium and silver, and introducing with said catalyst approximately 2% of a simple aliphatic acid selected from the group of suitable acids consisting of acetic, phosphoric, tartaric, glycollic and lactic acids.

2. The process of treating tobacco as defined in claim 1, including the step of adding approximately 10% of invert sugars, such as uncrystallizable syrups, molasses, honey and the like.

References Cited in the file of this patent UNITED STATES PATENTS 70,386 Arnd Nov. 5, 1867 467,055 Schneider Jan. 12, 1892 1,845,264 Grunauer Feb. 16, 1932 2,003,690 Lewton June 4, 1935 2,029,494 Loewenthal Feb. 4, 1936 2,067,338 Power Jan. 12, 1937 2,371,389 Goepp Mar. 13, 1945 2,429,567 Sowa Oct. 21, 1947 FOREIGN PATENTS 11,337 Germany Feb. 22, 1880 69,355. Denmark June 13, 1949 369,544 'Great Britain Sept. 16, 1930 436,445 Great Britain Oct. 4, 1935 567,098 Germany Apr. 26, 1933 599,816 Great Britain Mar. 22, 1948 670,855 Germany Jan. 26, 1939 Germany May 31, 1939

Claims (1)

1. THE PROCESS OF TREATING NORMALLY DISCARDABLE AND POOR QUALITY PORTIONS OF TOBACCO LEAVES TO PRODUCE USEFUL CIGARETTE AND PIPE TOBACCO OF HIGH QUALITY, COMPRISING DISPERSING IN SAID PORTIONS NOT MORE THAN APPROXIMATELY 2% BY WEIGHT OF A PRIMARY CATALYST CONSISTING OF AT LEAST ONE SUITABLE SALT SELECTED FROM THE GROUP OF SALTS OF THE METALS CONSISTING OF SALTS OF COBALT, MANGANESE, NICKEL, COPPER, CHROMIUM AND SILVER, AND INTRODUCING WITH SAID CATALYST APPROXIMATELY 2% OF A SIMPLE ALIPHATIC ACID SELECTED FROM THE GROUP OF SUITABLE ACIDS CONSISTING OF ACETIC, PHOSPHORIC, TARTARIC, GLYCOLLIC AND LACTIC ACIDS.