US3256889A - Process for the treatment of tobacco - Google Patents

Description

United States Patent 3 256,889 PROCESS FOR THE TREATMENT OF TOBACCO Roger L. de la Burd, 1617 Pope Ave., Richmond, Va., and Frank H. Crayton, 6343 Glyndon Lane, Richmond 25, Va. No Drawing. Filed Nov. 30, 1962, Ser. No. 241,124

g 2 Claims. (Cl. 131-141) This invention relates to a process for the treatment of tobacco. Moreparticularly, the invention [relates to a process for improving the smoking characteristics of tobacco.

It has long been a problem in the art that freshly harvested tobacco generally requires several years, involving a number of different treatments, before it is ready to be used in smoking products. For example, the harvested tobacco is generally dried for several months in order to cure it and the cured tobacco thereafter undergoes a number of sweating, redrying, resweating and aging operations which extend over a period of two to three years.

Numerous attempts have been made to shorten the period of time necessary to convert freshly harvested tobacco to a smoking product which has desirable flavor and smoking qualities. For example, bacteria have been added to tobacco and catalysts have been incorporated in tobacco in order to accelerate the fermentation process. However, none of these attempts has been found to be completely satisfactory.

It is an object of the present invention to provide an improved process for treating tobacco to improve the smoking characteristics thereof.

It is another object of the present invention to provide a process for up-grading tobacco to a satisfactory level of flavor and smoking qualities in a relatively short period of time.

It is also an object of the present invention to eliminate the disadvantageous changes which occur in the moisture retention properties of tobacco which has been treated by the conventional aging processes.

Additional objects of the present invention will be apparent from the following description.

I have discovered that the smoking characteristics of tobacco are greatly improved by the addition of a peptidic enzyme to the tobacco.

In accordance with the present invention, a peptidic enzyme is added to tobacco in an amount sufiicient to provide a tobacco composition containing from about 0.02 to about 0.15 percent, and preferably from about 0.05 to about 0.12 percent, by weight of added peptidic enzyme. This corresponds to adding from about 0.02 to'about 0.15 part by weight, and preferably from about 0.05 to about 0.12 part by weight, of peptidic enzyme per 100 parts of tobacco.

The enzyme can be applied in any suitable manner. However, it is generally applied to the tobacco in the form of a liquid solution, suspension or emulsion by spraying, dipping, brushing or other means.

The enzyme is preferably added to the tobacco as a 0.5 to 1.5% aqueous solution, with sufficient solution being added to bring the tobacco to a moisture content of 15 to 45% and is most preferably added to the tobacco as a 0.5 to 1.5 solution, with suflicient solution to bring the tobacco to a moisture content of 15 to 25% by weight.

The preferred method of adding the enzyme is to spray a solution of it on tobacco leaves, since by this method the moisture content of the sprayed leaves can readily be controlled. The pH of the enzyme solution can be adjusted to a value between about 5.2 and 8.5 by the addition of suitable agents, such as sodium hydroxide, ammonium hydroxide, dilute acetic and sulfuric acid, and the like but is preferably adjusted to a value of from about 6.5 to 7.6, in order to best facilitate the action of the enzyme.

The moisture content of the treated leaves is important and should be from about 15% to about after the addition of enzyme. At least 15% moisture is necessary in order to produce a product having sufficient mildness. The upper limit of 40% is necessary, since raising the moisture content of the leaves above the level irreversibly decreases some of the improved smoking characteristics which would otherwise be obtained by the present enzyme treatment of the leaves.

The addition of the enzyme to the tobacco can be conducted at temperatures of from 60 to 140 F. but is preferably conducted at room temperature.

The peptidic enzymes .of the invention include mono-, di-, and tri-polypeptidases, carboxy-peptidase, endopeptidases, aminoacylases, aminopeptidases, dehydropeptidases, and dipeptidases which have specificity for amino acids, amino acid amides, diand tripeptides, polypeptides, and dehydropeptides. The best source of such enzymes is hog kidney although they can be extracted from intestinal mucosa, liver, and similar animal tissues. These enzymes may be employed either alone or in combination.

In accordance with one embodiment of the present invention, the peptidic enzymes are added to the tobacco with proteolytic enzymes in the ratio of from 1:10 to 1:1, respectively. The proteolytic enzymes which can be employed can be of the same type employed in my copending application Serial No. 241,123, filed of even date herewith. When these two enzymes are used in combination the amount employed should be such that the first product contains a total of from 0.28 to 0.56% by weight of added enzymes in the ratios given above. Apart from this requirement, the addition of the two types of enzymes will be the same and the remainder of the tobacco treatment can be the same as if the peptidic enzyme were employed by itself.

The enzyme should be evenly distributed throughout the tobacco leaves. It can then be placed in suitable containers, such as polyethylene bags, which will prevent evaporation of moisture in the mixture.

The resulting enzyme-tobacco mixtures can then be placed in an atmosphere, for example a humidity cabinet, maintained at 60 to 140 F. and 45 to 85% relative humidity for a period of from 1 to 200 hours.

The tobacco parts can then be removed from the above atmosphere and can be placed in an environment maintained at a temperature of from 60 to 80 F. and 60 to relative humidity, in order to permit the moisture content of the leaves to reach a value of from about 11 to about 14%, preferably about 12%, by weight.

Tobaccos which can be treated in accordance with the present invention can be of any quality or origin. For example, the tobacco can be low grade or high grade domestic tobacco, for example bur-ley, Maryland, bright or Virginia tobaccos ormixtures of these. The tobacco same low-grade bright tobacco. in the cigarette fillers.

can also be, for example, an imported aromatic or oriental tobacco or mixtures of these, including mixtures with EXAMPLE 1 Twenty-four .pounds of the full leaves of an unaged low-grade bright tobacco (RDZ) were conditioned to moisture in a humidity cabinet and were sprayed at room temperature in separate two-pound batches with 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 2.0, 3.0, 4.0, 5.0 and 6.0% (by weight) aqueous solutions of peptidase (obtained from Nutritional Biochemicals Corporation) and comprising a mixture of peptidic enzymes.

In each case, sufficient solution was employed to bring the moisture content of the leaves to -22% (by weight). Each batch of leaves so treated was mixed thoroughly and packed loosely in polyethylene bags. The bags were closed to prevent evaporation of the moisture and were then placed in humidity cabinets maintained at a temperature of 100 F. and at 70% relative humidity for 60 hours.

Following this treatment, the leaves were removed from the polyethylene bags and placed loosely on wire mats in a room maintained at a temperature of 75 C. and at a relative humidity of 60% until the moisture in the leaf had a value of about 12% by weight, which required about 24 to 48 hours.

In each case, visual examination of the leaves showed no change in the appearance of the tobacco.

The treated tobacco leaves which had been sprayed with a 1.0% aqueous solution of peptidase and untreated leaves of the same tobacco were each separately immersed for 15 minutes in a 0.1 N solution of sodium hydroxide. The resulting solutions were dialyzed in a Visking dialysis tube against distilled water. The liquids which remained in the dialysis bag were precipitated with ammonium chloride and the precipitates were weighed. Since the -membrane of the dialysis tube did not allow the passage of substances having a molecular weight higher than 10,000, the reduction of substances below the 10,000 molecular weight could be calculated from the treated tobacco and the untreated control. A reduction of approximately 40% was calculated, showing that the action of the peptidase on the tobacco had produced a structural change within the leaf by reducing the molecular weight of the polypeptides in the leaf. The peptidase had cleaved the longchain peptides into lower molecular weight units. The tobacco leaves which had been treated as above with a 1.0% solution of peptidase and its control sample were also analyzed for their free amino acid content. The tobacco was water-extracted and the extract was examined on an automatic amino acid analyzer; This analysis showed that the treatment with peptidase increased the free amino acid content by approximately 27%.

Cigarettes were made from each batch of the enzymetreated tobacco and from untreated unaged leaves of the No additives were used Subjective evaluations of the cigarettes by a smoking panel of 59 members showed that the cigarettes from the enzyme-treatedv tobacco were preferred over cigarettes from the untreated tobacco. The panel found that the smoke from the treated tobacco was much more mild than that from the control and that it had a note of sweetness, a fuller body, and a more desirable flavor than that from the control cigarette. Several of the smokers observed that the desirable flavor increased in intensity during the smoking of the cigarette.

Data on the subjective evaluation showed that there was an optimum concentration level for the enzyme above and below which the development of flavor and aroma was not complete. This trend is shown by the data presented below in Table I.

It can be seen from Table I that the best results were obtained when the peptidase was applied at 0.6 to 1.4% concentration. Smoke from tobaccos treated with concentrations exceeding 3% was more harsh and had a greater bitey-ness than did the smoke from the control.

Table I TEST PANEL EVALUATIONS OF UNAGED LOW-GRADE BRIGHT TOBACCO CONTAINING PEPTIDASE 1 A scale of 5 to +5 was employed, 5, being the poorest rating, 0 being the characteristics of the control, and +5 being the best rating.

Visual comparisons of the materials tested showed that the ash from the treated cigarettes compared well with that from the untreated and that the burning rate and filling power of the tobacco had been improved by the treatment.

EXAMPLE 2 Twenty-four pounds of the full leaves of a good grade bright tobacco (E7) were treated as described in Example 1 and sprayed at room temperature in separate two-pound batches with 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 2.0, 3.0, 4.0, 5.0, and 6.0% (by weight) aqueous solutions of the same type peptidase and in the same manner as employed in Example 1.

The leaves were further treated in the manner described in Example 1 and were brought to a moisture content of about 12% by weight.

In each case, visual examination of the leaves showed no change in the appearance of the tobacco.

By using the methods described in Example 1, it was determined that the molecular weight of the polypeptides in the tobacco had been reduced about 40%, showing that the peptidase had cleaved the long-chain peptides into lower molecular weight units. Analyses of the free amino acid content of the leaves, as described in Example 1, showed that the treatment with peptidase had increased the free amino acid content by approximately 30%.

Cigarettes were made from each batch of the enzymetreated tobacco and from untreated unaged leaves of the same good-grade bright tobacco. No additives were used in the cigarette filters.

Subjective evaluation of the cigarettes by a 59-member smoking panel showed that the cigarettes from the enzymetreated tobacco were preferred over cigarettes from the untreated tobacco at a -1 probability level. The smokers found that the smoke from the treated tobacco was much more mild than that from the control, and that it had a fuller body, a note of sweetness, and a more desirable aroma and flavor. Data on the subjective evaluation showed a trend which indicated that the optimum results were obtained when the peptidase was applied at a 0.4 to 1.4 concentration. This trend can be seen from the data in Table II.

TEST PANEL EVALUATIONS OF GOOD GRADE B RIGHT TOBACCO CONTAINING PEPTIDASE Average Rating 1 From 59 Panelists Percent Concentration Harshness Aroma Preference 0.2 0. 0. 00 +0. 0.4 +0. 62 0. 00 +0. 05 0.6." 05 +0.12 +0.05 0.8.-. +1. 62 +1.12 +2. 62 1.0-.. +2. 66 +3. 25 +4. 37 1.2. +1. 37 +2. 00 +2. 00 1 4 0. 00 +0. 33 +0.50 2 0. 62 0. 00 0. 33 3.0 2. 00 -l. 00 1.l2 4.0 2. 00 -1. 12 -1. 12 5.0 2. 00 l. 62 1. 26 6.0 1. 67 -2. 25 2. 00

1 Same scale as in Table I.

EXAMPLE 3 Five pounds of a good quality bright tobacco (RDA) of the crop year 1959 was sprayed with a 1% aqueous solution of the peptidase described in Example 1, in an amount suflicient to bring the moisture level of the leaves to 19%. The leaves were then treated as in Example 1, and equilibrated to 60% RH. and 75 F. to bring the moisture content to 12%.

Visual examination showed that the appearance of the tobacco was unchanged.

Cigarettes were prepared in the conventional manner from the treated tobacco and from naturally aged and unaged leaves of the same good-quality stock. These cigarettes were smoked and evaluated in three different smoking panel tests. The subjective evaluation by one of the tests with 31 panel members showed that the cigarettes from the treated tobacco showed a slight trend toward an improvement in flavor over the cigarettesprepared from untreated naturally-aged tobacco. A trend in preference for the cigarette from the treated tobacco was also ob- In subjective tests by a 39-member smoking panel, the enzyme-treated tobacco was judged by statistical evaluation to have lower mouth harshness and over all better smoking characteristics.

EXAMPLE 5 Leaves of a low-grade bright tobacco (X-1 2) were treated as described in Example 1 with each of three lots of peptidase (Lots 2121, 2574, and 3154 from Nutritional Biochemicals Corporation). Each lot was used at a 0.3, 1.0, and 5.0% level of concentration.

Cigarettes made from the treated tobacco were compared with cigarettes prepared from unaged and forceaged leaves of the same low-grade stock. The forceaged leaves had been submitted to accelerated aging in a manner similar to that described in Industrial and Engineering Chemistry, 44, p. 284 (1952) by F. Darkes et al. Subjective evaluation of the smoke by a 39-member smoking panel showed that the cigarettes from the enzymetreated tobacco used at a 1% level were much preferred over those from either the unaged or force-aged tobacco. The cigarettes made from the tobacco treated with 0.3 and 5.0% concentrations showed no statistically significant improvement over the controls.

The data which illustrates the improvement in the cigar- .ettes treated at the 1% level of enzyme concentration are given below. They are expressed as t-test values. These values represent a statistical evaluation based on precise laws of probabily. Because of variations in subjective evaluation, two samples may seem to be different even though they have come from an identical source. The t-test determines the limits within which this variation would fall with known probability. The magnitude of this difference indicates the probability that the sources are or are not identical, and that the differences are true differences. Because of the size of the sampling, these particular values can be interpreted to mean that the treated cigarettes were preferred over the untreated controls at a 1001 probability level.

Table III Enzyme treated vs. unaged Enzyme treated vs. force-aged Enzyme Lot N o. Harshness Taste Preier- Harshness Taste Prefer- Intensity ence Intensity ence t=3.28 15:2.48- t=2.3 No Sig t=2.65 t=2.2 t=2.18 No sig t=2.32 t=2.15 N0 sig- No slg t=3.2 t=2.3 N0 sig- No sig t=2.3 t=2.1.

We claim:

served. In a second test with 25 panel members, the preference for the cigarette from the treated tobacco over that from naturally-aged tobacco was statistically significant. The evaluation also showed a trend toward better flavor and less harshness for the experimental cigarette.

Subjective evaluation of the cigarette from the enzymetreated tobacco versus the cigarette from unaged, untreated tobacco showed that the experimental cigarette was significantly less harsh and significantly preferred. Fiftyseven panel members participated in the evaluation. Two additional evaluations of the same cigarettes by a 29- member and by a 50-member panel showed a trend toward less harshness in the experimental cigarette.

EXAMPLE 4 Old Belt tobacco (078X) was treated as described above 1. A process for the treatment of tobacco, which comprises adding to the tobacco a non-living composition comprising a peptidic enzyme selected from the group consisting of monopolypeptidases, dipolypeptidases, tri-.

polypeptidases, carboxypeptidase, endopeptidases, aminoacylases, aminopeptidases, dehydropeptidases and dipeptidases which have specificity for amino acids, amino acid amides, dipeptides, tripeptides, polypeptides and dehydropeptides, said composition being added to the tobacco in an amount corresponding to from about 0.02 to about 0.15 part by weight of peptidic enzyme per parts of tobacco, said compositon containing from 98.5 to 99.5 parts by weight of water and from 0.5 to 1.5 parts by weight peptidic enzyme, subjecting the resulting mixture without removing any portion thereof to a temperature of from 60 to F., for a period of one to 200 hours, bringing the moisture content of said mixture to a value of 9 to 15% by subjecting the mixture to a temperature of 60 to 80 F. and thereafter incorporating the entire tobaccowater-enzyme composition in a smoking product, whereby the resulting smoking product contains all of the products of the reactions of the tobacco-water-enzyme composition and all of the unreacted components of the tobacco-water-enzyme composition.

2. A process for the treatment of tobacco, which comprises adding to the tobacco a non-living composition comprising a peptidic enzyme selected from the group consisting of monopolypeptidases, dipolypeptidases, tripolypeptidases, carboXypeptid-ases, endopeptidases, aminoacyla es, aminopeptidases, dehydropeptidases and dipeptidases, and a proteolytic enzyme selected from the group consisting of ficin, pepsin, trypsin, chymotrypsin, erepsin, fungal protease, protease and papain, said composition being added to the tobacco in an amount corresponding to from about 0.02 to about 0.15 part by Weight of peptidic enzyme per 100 parts of tobacco, said composition containing from 98.5 to 99.5 parts by weight of water and from 0.5 to 1.5 parts by Weight of peptidic and proteolytic enzyme, said peptidic and proteolytic enzyme being in the weight ratio of from 1:10 to 1:1 respectively, subject the resulting mixture, without removing any portion thereof to a temperature of from 60 to 140 F., for a period of from one to 200 hours, bringing the moisture content of said mixture to a value of 9 to 15% by subjecting the composition to a temperature of from 60 to 80 F., and thereafter incorporating the entire tobacco-water-enzyme composition in a smoking product, whereby the resulting smoking product contains all of the products of the reactions of the tobacco-water-enzyme composition and all of the unreacted components of the tobacco-water-enzyme composition.

References Cited by the Examiner UNITED STATES PATENTS 2,475,568 7/1949 Moore 13-1-140 3,106,209 10 /1963 Torigian 131 3,132,651 5/1964 Kiefer 131-141 FOREIGN PATENTS 252,121 10/1912 Germany.

OTHER REFERENCES Chemistry and Methods of Enzymes, by J. B. Summer and G. F. Somers, p. 172, published 1953 by Academic Press Inc., New York, NY.

Chemistry and Methods of Enzymes, by I. B. Summer and F. Somers, 3rd Edition, published 1953 by Academic Press Inc., New York, N.Y., pp. 166 and 167.

Enzymes, by M. Dixon and E. C. Webb, pp. 266 and 267, published 1958 by Academic Press Inc., New York, NY.

Shmuk: The Chemistry and Technology of Tobacco volume III, pp. 474 and 475, published for National Science Foundation, Wash, DC. by Israel Program for Scientific Translations in 1961.

Websters Third New International Dictionary, p. 1674, published 1961 by G. and C. Merriam Co., Springfield, Mass.

SAMUEL KOREN, Primary Examiner.

Claims (1)

1. A PROCESS FRO THE TREATMENT OF TOBACCO, WHICH COMPRISES ADDING TO THE TOBACCO A NON-LIVING COMPOSITION COMPRISING A PEPTIDIC ENZYNE SELECTED FROM THE GROUP CONSISTING OF MONOPOLYPEPTIDASES, DIPOLYPEPTIDASES, TRIPOLYPEPTIDASES, CARBOXYPEPTIDASE, ENDOPEPTIDASES, AMINOACYLASES, AMINOPEPTIDASES, DEHYDROPEPTIDASES AND DIPEPTIDASES WHICH HAVE SPECIFICITY FOR AMINO ACIDS, AMINO ACID AMIDES, DIPEPTIDES, TRIPEPTIDES, POLYPEPTIDES AND DEHYDROPEPTIDES, SAID COMPOSITION BEING ADDED TO THE TOBACCO IN AN AMOUNT CORRESPONDING TO FROM ABOUT 0.02 TO ABOUT 0.15 PART BY WEIGHT OF PEPTIDIC ENZYNE PER 100 PARTS OF TOBACCO, SAID COMPOSITION CONTAINING FROM 98.5 TO 99.5 PARTS BY WEIGHT OF WATER AND FROM 0.5 TO 1.5 PARTS BY WEIGHT PEPTIDIC ENZYNE, SUBJECTING THE RESULTING MIXTURE WITHOUT REMOVING ANY PORTION THEREOF TO A TEMPERATURE OF FROM 60 TO 140*F., FOR A PERIOD OF ONE TO 200 HOURS, BRINGING THE MOISTURE CONTENT OF SAID MIXTURE TO A VALUE OF 9 TO 15% BY SUBJECTING THE MIXTURE TO A TEMPERATURE OF 60 TO 80*F., AND THEREAFTER INCORPORATING THE ENTIRE TOBACCOWATER-ENZYME COMPOSITION IN A SMOKING PRODUCT, WHEREBY THE RESULTING SMOKING PRODUCT CONTAINS ALL OF THE PRODUCTS OF THE REACTIONS OF THE TOBACCO-WATER-ENZYME COMPOSITION AND ALL OF THE UNREACTED COMPONENTS OF THE TOBACCO-WATER-ENZYME COMPOSITION.