FR2512646A1 - Mfg. smoking tobacco prod. with good flavour - by removing protein, nicotine and green pigments from tobacco leaves - Google Patents

Abstract

A smoking tobacco prod. is obtd. by (a) converting tobacco leaves to a pulp comprising a mixt. of a coarse solid portion and a liq. portion contg. water-soluble plant material and a suspension of finely particulate material; (b) sepg. the solid and liq. portions; (c) removing the particulate material from the liq. portion; (d) sepg. water-soluble protein and nicotine from the liq. portion; (e) sepg. pigmented material from the solid portion and particulate material; (f) sepg. green from non-green components of the pigment pigmented material; and (g) recombining the depigmented solid material, the liq. portion from which protein and nicotine have been removed, and the non-green pigmented components. The prod. has a reduced protein, nicotine, and tar content, but retains desirable flavour constituents. The process is less labout-intensive than conventional processes.

Description

 The invention relates as a whole to a process for obtaining a product to be produced from tobacco plants.

In a more particular aspect, it relates to a process for removing proteins, nicotine and the green pigment from tobacco for use in cigarettes and other tobacco manufacturing products.

 Cigarettes and other tobacco products are mostly blends of two main types of tobacco, namely chimney-ripened tobacco and burley tobacco. American cigarettes, for example, are generally two-thirds formed tobacco matured in the chimney and a third of burley tobacco.

 The cultivation of chimney-ripened tobacco and burley tobacco is mainly carried out in the states of North Carolina, Virginia, Xentucky, Tennessee, South Carolina and Georgia. The production of tobacco matured in chimneys takes place largely in a region close to the Atlantic coast, while burley tobacco is cultivated in regions located more inland and higher up. The culture and harvest of chimney-ripened tobacco and that of burley tobacco differ in various ways.

 In the case of chimney-ripened tobacco, the lower leaves are detached from the plant stem as they mature and begin to turn yellow.

The loose leaves are hung in bundles on sticks which are hung in hangars - and the tobacco is "matured in a chimney", that is to say dried by air, heated by heat exchange with hot air passing through chimneys.

 On the other hand, burley tobacco is allowed to ripen until almost all of the leaves have turned yellow on the stems. Then cut the whole plant close to the ground and allow the stem and leaves to wilt on the ground for several days. The whole plant is then hung in specially designed hangars where it is allowed to air dry in a process of slow ripening.

 The cultivation of tobacco, particularly tobacco dried in a chimney, is a laborious process. Consequently, attempts have inevitably been made to mechanize this process.

To this end, the United States Department of Agriculture has developed a process known as the "ripening process for homogenized leaves, which is less expensive than conventional ripening processes.

 In this process, the yellowed leaves of conventionally grown tobacco plants are harvested and made into pulp. Water is added to the pulp which is then stirred at a temperature of about 250C for about 24 hours. During this period, the proteolytic enzymes already in the leaves digest some of the proteins that remain in the leaves when they are harvested. After digestion, the excess water is expressed from the now dark brown pulp which is then dried and which serves as a starting material for obtaining a reconstituted tobacco product used as tobacco filler in the manufacture cigarettesvtout like low quaity tobacco obtained as a product of conventional ripening processes.

 The resulting product is sometimes less dangerous to smoke than tobacco obtained by conventional ripening processes, since its protein concentration is reduced, proteins constituting one of the sources of undesirable products in cigarette smoke.

 As in conventional cultivation, it is extremely important that tobacco leaves can naturally turn yellow before they are harvested for use in the ripening process of homogenized leaves. However, the homogenized ripening process is not capable of removing enough green pigment from the leaves for the product to be acceptable to the tobacco industry.

 During the characteristic slow combustion of tobacco products such as cigarettes, pipe tobacco and cigars, nicotine, "tars" and other products considered to have harmful effects on the health of the smoker are released into the smoke which is sucked into the smoker's mouth and lungs. For health reasons, cigarette manufacturers have developed systems to reduce the nicotine and tar content of burning tobacco. However, most of this reduction has not been achieved by the development of new varieties of tobacco with low tar and nicotine content. On the contrary, it was obtained by changing the way cigarettes are made.

 Thus, extensive use has been made of filters which partially reduce the tar content. However, most of the reduction has resulted from so-called "bypass" systems that use porous paper in the manufacture of cigarettes to allow air to be drawn in through pores in the paper to dilute the gases generated by the product. burning tobacco.

 Although these techniques have resulted in a product that is less dangerous to smoke, they do not completely eliminate the unwanted constituents of tobacco smoke. In addition, such methods result in a reduction in the components that flavor the smoke and this reduction in taste has been criticized by smokers. As a result, it is necessary to find a tobacco product which has a naturally low nicotine and tar content, but which retains the important taste-communicating ingredients.

 Accordingly, one of the objects of the present invention is a tobacco product suitable for use in cigarettes and other manufactured forms of tobacco, which has a reduced protein content of nicotine and tar, but which retains the beneficial constituents of the taste.

 Another object of the invention is to develop a process for obtaining a tobacco product suitable for use in cigarettes and other smoking products, which is less laborious than conventional processes.

 Other characteristics and advantages of the present invention will emerge from the detailed description which follows.

 The present invention provides a method of treating tobacco, even immature tobacco, to obtain a protein-free tobacco, suitable for use in cigarettes and other tobacco products, having a reduced tar content, including nicotine. and the green pigments have been eliminated. This process consists in transforming tobacco into a pulp comprising a liquid portion and a solid portion, the latter comprising a coarse fibrous material and a material in fine particles. The liquid portion, a solution of water-soluble proteins and other water-soluble vegetable matter, is freed of proteins and treated for the elimination of nicotine.

 Pigments are removed from the coarse fibrous material and the fine particle material and are divided into green pigments and non-green pigments. The non-green pigments, the protein-free solution and the depigmented fibrous material are combined to form a tobacco product suitable for use as a tobacco filler in cigarettes and other manufactured tobacco products.

 The method of the present invention can be applied to obtaining a protein-free tobacco product, from which nicotine and green pigments are also eliminated, from the leaves of tobacco plants of all types. The process is well suited to the processing on an industrial scale of tobacco matured in a chimney or burley tobacco, that is to say the tobacco most widely used in the manufacture of cigarettes.

 The method of the present invention can exploit the leaves of mature tobacco plants as used in conventional methods. However, it is also suitable for the use of the leaves of plants which are below maturity, that is to say leaves which have not yet started to yellow naturally. In the latter case, and in particular if the plants are very immature, the whole plant, that is to say leaves and stems, is used in the present invention.

 The ability of the process of the present invention to be applied to immature plants has the advantage that a relatively short growth period is sufficient before the plants are harvested for use in the process. In regions where the growing season is long enough, this offers the possibility of growing more than one crop in a single season.

 When the leaves have been detached from the tobacco plant, they are treated alone or with the stem if small plants constitute the source of the leaves, by crushing, crushing, or other method of reduction to a pulp to release the liquid portion of the solids sheets. This liquid portion contains the water-soluble proteins that appear in tobacco. The liquid portion is preferably freed of proteins according to the process described in US Patent No. 4,268,632.

 The use of this method makes it possible to isolate ribulose-1,5-diphosphate-carboxylase, known to specialists under the name of "fraction I" protein, product of commercial interest, and of fraction II protein. In this process, when the leaves have been detached from the tobacco plant, they are treated alone or jointly with the stem if small plants are the source of the leaves, by crushing, crushing or other method of reduction to a pulp to release the liquid portion of the solids sheets. Preferably, the pulping process is carried out in the presence of a reducing agent. In this regard, the pulping process allows the phenol-oxidases present in the leaves to come into contact with the proteins of the latter. This results in the oxidation of aromatic amino acids such as tyrosine, which constitute a part of the primary structure of proteins. This oxidation modifies proteins, which manifests itself visually by their browning, and lowers their solubility in water. The reducing agent effectively behaves like an antioxidant by suppressing this oxidation.

The reducing agent which is appreciated for use in accordance with the invention is 2-mercapto-ethanol because it is volatile and because it evaporates during the subsequent treatment described below, leaving little or no by leaving no residue in the isolated material. However, other reducing agents may also be used. Among such agents, sodium metabisulfite and dithiothreitol are mentioned.
The separation of any residue from these agents can be carried out by conventional operations. The quantity of reducing agent sufficient to limit the oxidation can vary, for example depending on the agent which one chooses to use. In the case of 2-mercapto-ethanol, effective suppression of unwanted oxidation can be achieved by using about 5 ml of the liquid agent per kg of plant material being treated.

 The liquid portion of the plant material contains the plant proteins in dissolved form.

Heat treatment of the liquid portion of the pulp containing ribulose-1,5-diphosphate-carboxylase, followed by cooling, causes this protein to separate from the liquid by crystallization. The mechanism by which heat treatment induces crystallization is not obvious. However, it is believed that the heat treatment modifies the protein in some way which promotes crystallization.

 The solid material contained in the pulp comprises the coarse green pigmented material, easily separated and the green pigmented material in fine particles which is difficult to separate from the liquid and which includes pigmentary materials, a starchy material and a proteinaceous material insoluble in the 'water. However, the heat treatment of the invention, the details of which will be given below, not only induces the crystallization of the protein of fraction I, but also causes the partial coagulation of the material into fine particles pigmented in green, this which facilitates its elimination during subsequent treatment. For example, this material can be removed by moderate centrifugal force, therefore heat treatment is applied to the liquid portion before this portion is separated from the coarse solid material. Heating the entire pulp, i.e. before any solid material has been removed, is preferable because this results in better yields of crystalline ribulose-1-, 5-diphosphate carboxylase than if heating was conducted after removal of the coarse material, but before removal of the pigmented material.

 The heating step is carried out at a temperature and for a period sufficient to induce the crystallization of ribulose-1,5-diphosphate-carboxylase in the form of octagonal crystals, in the liquid portion of the pulp when the liquid is cooled. However, in no case should the liquid portion be heated above the temperature at which the protein denatures, namely around 520C, and immediately precipitates into an insoluble mass.

 Although temperatures below 520C can be used, it is preferable to use a temperature of at least about 480C, because below this temperature, the green pigmented materials do not coagulate enough to allow their elimination easy. In addition, below 480C, the heating time required to induce crystallization of ribulose-1,5-diphosphate carboxylase can be undesirably long. The best results are obtained by heating the liquid portion at 500 + 10C for about 15 to 20 minutes.

 The time between harvesting the leaves, converting them to a pulp and heating the pulp as described above reduces the yield of crystalline ribulose1,5-diphosphate carboxylase which can be obtained by the the present invention. Consequently, these operations must be carried out as quickly as possible. To this end, it is preferable to conduct these operations on the site or near the culture site as the leaves are harvested.

 The transformation of the leaves into a pulp can be carried out by grinding, crushing or by another suitable process.

 The heat treatment can be carried out continuously or discontinuously. In a batch process, the pulp is placed in a container under selected heating conditions so that no part of the pulp or at least its liquid portion is heated to a temperature at which the protein is denatured. As indicated above, the pulp is preferably heated to a temperature of 50 + 10C for about 15 to about 20 minutes.

 In a continuous process, the pulp is pumped without undesirable agitation by coils immersed in a liquid heated to a selected temperature so that, by heat exchange, a specified volume of pulp is heated to 50 + 10C for about 15 to about 20 minutes, then by coils in contact with a liquid at a temperature below 500C to reduce the temperature of the pulp.

 After being heated, the liquid and solid portions of the pulp are separated. The separation is advantageously carried out by prior pressing of the pulp to express the liquid portion. The liquid obtained in this way constitutes a "green juice" containing the material pigmented in green. When this material is heated above about 480C to cause coagulation, it is simply removed, for example by filtration or moderate centrifugation to give a "brown juice".

 To obtain ribulose-1., 5-diphosphate-carboxylase, the brown juice is cooled and stored at a temperature at which crystallization takes place, usually at or below room temperature. Particularly advantageous results have been obtained by cooling the brown juice to about 80C for about 24 hours. The crystallized ribulose-1, 5-diphosphate-carboxylase is separated from the supernatant liquor by filtration or by centrifugation.

 The supernatant liquor contains the proteins of fraction II and a port of the non-crystallized protein of fraction I. These proteins can be collected by acidification of the supernatant liquor, which causes their precipitation. The best results are obtained by acidification to a pH of around 4.5. A smaller amount of this protein is precipitated if a pH of 4, C or 5.0 is used.

 The description given above has to show the process in which the whole pulp is heated before the separation of the liquid portion. However, as indicated above, the heating step can be carried out after the liquid portion containing a suspension green pigmented matter has been separated from the pulp. Furthermore, when the protein of fraction I is not desired to be obtained separately, the heat treatment described above can be neglected and the liquid portion can be acidified to precipitate, or otherwise treated to separate, the water-soluble proteins without separate the proteins from reactions I and II.

 After removal of the proteins, the resulting light brown liquid, now almost free of any protein, but containing all of the other water-soluble natural products that were present in the tobacco plants, is treated with a base to adjust the pH. above 7.0, then steam distilled to remove nicotine. After steam distillation, the liquid is evaporated to dryness giving a brown residue having roughly the consistency of molasses. This residue is kept for later use, as described below.

 The pulp is wrung out to separate the liquid portion which is treated as described above.

The remaining residue, which is a coarse green material containing about 70% water, is suspended in a suitable solvent to extract the green pigmented material. Methanol or acetone can be used for this purpose. In the case of methanol, a sufficient volume of 100% methanol is added so that the methanol is diluted with the water remaining in the green residue to a concentration of approximately 90% methanol. When acetone is used, it is in an amount which is diluted to a concentration of 80% acetone per residual strip of the green residue. When the green residue is suspended in the chosen solvent, the extraction of the green color is rapid and total, leaving a fluffy fibrous mat ranging from light brown to almost white, from which the solution of pigmented material is easily separated by spin-filtration or other suitable operation.

 The residual solvent is removed from the fibrous residue by evaporation and produces a dry, discolored residue with a pleasant odor, which undergoes a subsequent treatment as indicated below.

 The green mud obtained by separation of the liquid portion is discolored essentially in the same way as the coarse residual material described above. Thus, the green mud is suspended in methanol or acetone or in another suitable solvent for extracting the pigmented materials in order to leave a practically white dry product which is formed of the proteins insoluble in water and of the material. starch content in tobacco leaves.

 Pigmented materials obtained from coarse solids and green mud are collected by separation of the discolored solids from the liquid extracted from which the methanol or acetone is evaporated. A suspension is thus obtained comprising globules of materials pigmented in green, insoluble in water, in suspension in water which contain yellow pigmented materials which are water-soluble. These are collected by evaporation of the water for subsequent use.

 The separation of the green pigmented materials from the coarse green residue or from the green mud can be carried out individually or by combining the solvent extraction phases coming from the discoloration of the two solid materials.

 It is known that the water-soluble yellow pigmented material thus isolated from the green pigmented material oxidizes during the maturation of conventional tobacco with a view to obtaining structured materials of the quinine type.

Consequently, in a preferred embodiment of the present invention, this material or at least a portion of this material is oxidized in order to obtain similar products. Preferably, the oxidation is carried out by adding a sufficient quantity of ammonium hydroxide or other volatile bases which have ignition points similar to or lower than that of water or by bubbling ammonia gas into the aqueous solution containing the material pigmented in yellow to adjust the pH to a value of about 10.5. Air or oxygen is then bubbled through the solution until it turns brown. The brown solution is then heated to remove ammonia and volatile bases, including nicotine. The resulting brown solution is retained for subsequent use as described below.

 The green pigmented materials obtained by evaporation of the methanolic or acetonic solvent from the solution of pigmentary materials are then treated, in a preferred embodiment of the present invention, to separate green pigmented materials from yellow-orange pigmented materials which are also insoluble in water. To do this, the tar-like material obtained when the solvent is removed by evaporation of the solution of the pigmented materials, is suspended in 2N potassium hydroxide containing 20% methanol, then heated in a closed container or in another reflux device at about 60 OC until the material has dissolved.

 When all the material has dissolved, the solution is cooled to 250C and the dissolved material is subjected to a liquid-liquid extraction using a non-polar solvent, in order to extract the yellow-orange pigmented materials from the solution . Suitable solvents include non-polar aliphatic solvents such as petroleum ether, pentane, hexane or heptane, chlorinated solvents such as chloroform or dichloromethane; aromatic solvents such as benzene or toluene and cycloaliphatic solvents such as cyclopentane or cyclohexane.

 The non-polar solvent extracts the yellow-orange pigmented materials from the solution and these materials are collected by evaporation of the non-polar solvent used. Green pigments are not extracted by non-polar solvents, but remain dissolved in the methanolic solution of potassium hydroxide. The pigmented materials of yellow-orange color are kept for later use in the manner described below.

 As a result of the various operations described above, tobacco has been divided into components which are substantially free of protein, nicotine and green pigments. These materials can be recombined to obtain a deproteinized tobacco free of nicotine and green pigment, which can be used for cigarettes and other smokers' products. This is achieved by placing the discolored coarse solid in a rotating container which is equipped with sprayers and devices which provide sufficient heating to maintain the container at a temperature of about 70 to about 80 C. The container is also provided with means for to circulate air there.

 The water-insoluble yellow-orange pigment materials and the water-soluble yellow pigment materials which have not been oxidized are dissolved in a suitable solvent, for example ethyl alcohol, and the solution is applied. by spraying on the discolored residue at a controlled spraying speed which allows the residue to absorb these materials and to start to take on the brownish color characteristic of conventional matured tobacco.

 Then, the brown solution of water-soluble material obtained by oxidation of a portion of the material pigmented in yellow is applied by spraying onto the solid material, again at a controlled spraying speed so that the solid material can absorb the solution, to to improve more, color and to restore add-titanel scents and odoriferous components.

 Finally, the brown molasses-like residue obtained from the liquid portion by elimination of water-soluble proteins, is redissolved in water and the solution is applied to the residue to further enhance the color, aroma and taste of the reconstituted tobacco. . Agitation of the reconstituted tobacco is continued until the moisture content reaches a level of about 15 to about 20%. The product obtained in this way closely resembles, by its hue and texture, the reconstituted tobacco obtained from tobaccos matured in a conventional manner and used as filler, for example in the manufacture of cigarettes.

 As indicated in the table below, the tobacco product obtained from tobaccos both of the burley type and of the type matured in a chimney by the process of the present invention has a reduced content of nicotine, of reducing sugar and of products of extraction with petroleum ether, that is to say a reduced tar content.

% by weight on a dry basis
Nitrogen Sugar re- Nicotine Product
total NO3 extractor
with petroleum ~~~ ~~~~~~~~~ ~~~~~~~~~
Classic tobacco matured in a fireplace 2.25 0.08 13.95 1.98 6.77
TINTED DEPRO tobacco, type matured in a chimney 2.80 0.18 2.00 0.55 0.70
Classic burley type tobacco 4.15 0.63 2.90 3.31 6.07
DEPRO TINRE tobacco, burley type 3.00 0.47 1.90 0.70 0.82
In addition, as those skilled in the art can conceive, different characteristics can be given to re-formed tobacco by varying the proportions of the materials applied by spraying on the discolored residue obtained as a product of the process of the invention. , the product can be modified so that it has a low content of terpenes, sterols, carotenoids and other hydrocarbons. Reconstituted tobacco with low fatty acid and lipid content or reconstituted tobacco with low polyphenol and organic acid content is conceivable. it is also possible to reconstitute tobacco so that it contains either small amounts or amounts enriched in reducing sugars.

 Another advantage of the process of the present invention is that tobacco can be grown in such a way that its cultivation is less laborious than conventional cultivation.

For example, tobacco plants do not need to be grown to maturity and harvested in the conventional manner. On the contrary, it is possible to cultivate the plants and harvest them mechanically before maturity, then treat them in accordance with the present invention to obtain a product capable of. be used as a filler in cigarettes and other tobacco products, with a corresponding reduction in the time and labor required to grow tobacco in the conventional manner.

 Finally, if the process of the present invention involves the deproteinization of tobacco as described in the aforementioned US Patent No. 4,268,632, a water-soluble protein of commercial interest can be isolated from the leaves of tobacco and, at the same time, a tobacco product with reduced protein, nicotine and tar content can be obtained.

 It goes without saying that the present invention has been described for explanatory purposes, but in no way limiting, and that numerous modifications can be made thereto without departing from its scope.

Claims (13)

 1. Method for treating tobacco leaves to obtain a tobacco product suitable for use in a smoker's product from which proteins, nicotine and tar have been eliminated, method characterized in that it consists  (a) converting the leaves into a pulp comprising a mixture of a portion of coarse solid material and a liquid portion, the liquid portion containing the water-soluble vegetable material and a suspension of material in fine particles  (b) separating the coarse solid from the liquid portion  (c) separating the material into fine particles from the liquid portion  (d) separating the water-soluble protein and the nicotine from said liquid portion;  (e) separating the pigmented material from said coarse solid material and from said fine particle material  (f) separating the green pigmented components of said pigmented material from the green non-pigmented components; and  (g) recombining the depigmented coarse solid, the liquid portion from which the protein and nicotine have been removed and the components not shown in green.  2. Method according to claim 1, characterized in that the liquid portion is heated to a temperature lower than that at which the protein found in the liquid portion is denatured.  3. Method according to claim 2, characterized in that the heating is carried out for a period sufficient to crystallize the ribulose-1,5-diphosphatecarboxylase contained in said liquid portion when this portion is cooled, then the liquid portion is cooled to crystallize ribulose-1,5-diphosphatecarboxylase, said crystallized ribulose-1,5,5-diphosphate carboxylase preferably being separated from the liquid portion and an acid being added to the liquid portion to precipitate the residual water-soluble protein.  4. Method according to one of claims 2 and 3, characterized in that the liquid portion is heated before its separation from the coarse solid material.  5. Method according to any one of the preceding claims, characterized in that the liquid portion is heated to facilitate the separation of the material into fine particles, said heating to separate the material into fine patticles preferably being carried out before the material coarse solid has not been separated from the liquid portion.  6. Method according to one of claims 1 and 5, characterized in that the separation of the water-soluble protein from the liquid portion is carried out by adding acid to the liquid portion to precipitate the water-soluble protein.  7. Method according to one of claims 5 and 6, characterized in that the heating is carried out at a temperature of about 48 to 520C.  8. Method according to any one of the preceding claims, characterized in that the nicotine is eliminated from the liquid portion by steam distillation.  9. Method according to any one of the preceding claims, characterized in that the pigmented material is separated from the coarse solid material and from the material in fine particles by extraction using a solvent, preferably chosen from methanol. and acetone.  10. Method according to any one of the preceding claims, characterized in that the pigmented material is divided into a water-soluble fraction comprising the material pigmented in yellow and a water-insoluble fraction comprising a material pigmented in green and a pigmented material in yellow-orange insoluble in water, at least a portion of said yellow pigmented material soluble in water being preferably oxidized in the form of an aqueous solution.  11. Method according to any one of the preceding claims, characterized in that the pH of the solution is adjusted to approximately 10.5 by the addition of ammonium hydroxide and an oxygen source chosen between air and oxygen is bubbled through the solution until it turns brown, and the brown solution is heated to remove volatile bases and nicotine.  12. The method of claim 10, characterized in that the water-insoluble fraction is divided into a green pigmented material and a yellow-orange pigmented material, the latter being separated from the green pigmented material by dissolution of the water-insoluble fraction in 2N potassium hydroxide containing methanol and extraction of the resulting solution with a non-polar solvent to remove pigmented material of yellow-orange color, the non-polar solvent preferably being chosen between aliphatic solvents, chlorinated solvents, aromatic solvents and cycloaliphatic solvents.  13. The product of the process according to any one of the preceding claims.