US3316919A - Processing of smoking tobacco - Google Patents

Description

United States Patent 3,316,919 PROCESSING OF SMOKING TOBACCO Sydney James Green, Portswood, and William Brian Fordyce, Romsey, England, assignors to Brown and Williamson Tobacco Corporation, Louisville, Ky., a

corporation of Delaware No Drawing. Filed Apr. 21, 1964, Ser. No. 361,578 Claims priori application Great Britain, Apr. 29, 1963,

16,832/ 63 8 Claims. (Cl. 131--143) This invention concerns improvements relating to the treatment or processing of tobacco. An object of the invention is to provide a simple and practicable means by which the aroma and smoke flavour of a smoking tobacco can be improved or modified. Such improvement may be desirable because the tobacco is of a low grade or suflers losses of aroma or flavour constituents in the course of its preparation.

Some of the more volatile aroma or flavour constitucuts of tobacco are in fact lost during conventional processing of leaf-tobacco into a form suitable for smoking purposes. Attempts have been made to avoid these losses, for example by operating at low temperatures during conditioning, blending and cutting operations, but these have been only partially successful. Attempts to recover the aromatic substances from the atmosphere have also proved diflicult or impracticable. The present invention seeks, inter alia, to provide means by which volatile aromatic substances in tobacco can be extracted and used to make up losses from tobacco processed in the usual way.

According to the invention, tobacco, preferably in a ground state, is extracted with a chilled solvent such as ice-cold water and the liquid obtained by the extraction is solidified and freeze-dried. Preferably, a filter is employed to retain the tobacco during the extraction. Thus,

obviate substantially decomposition of the more unstable aroma and flavour constituents. For example, a rate of about 3-6 ml./minute may advantageously be used. The eflluent liquid may be collected in a receiver maintained at a temperature substantially below 0 C., so that it freezes almost immediately on contact with the walls. On completion of the extraction, the solidified liquid is freeze-dried, yielding a pale-brown product of high aromaticity.

This product, in the form of a fine powder, can be used to impart flavour and aroma to conventionally prepared smoking tobacco either by adding up to, say, 10%, but of the powder to the tobacco,

reconstituted tobacco products.

By such methods, which can be easily applied in practice, the impact aroma and smoke flavour of cigarettes can be appreciably changed by adding to the tobacco a freeze-dried extract from an aromatic or characterful tobocco. This may be done (a) to modify low grade flavour may be available from waste tobacco sources. In all cases, the flavouring tobacco may be a relatively cheap material.

Examples of ways of carrying the invention into etfect will now be more fully described:

Example 1 (a) parts of aromatic fire-cured tobacco were reduced to /8 inch diameter particles and extracted with chilled, preferably ice-cold, water using 6 parts by weight of water to each part of tobacco. The extraction was carried out at a rate of 5 mL/minu'te by percolation of the ice-cold water through a bed of supported by a filter screen.

In the extraction, it is important that the period of contact between the chilled water andthe tobacco should be substantially the same regardless of the quantity of tobacco. This involves co-relating the total flowrate to the area and porosity of the filter and the depth of the bed of tobacco. A flow-rate of .3-6 mL/min. may suitably be employed for a 2 inch depth of bed supported by a 4 inch diameter screenwith a range of maximum pore diameters of 15-40 microns (i.e. Grade No. 3 of British Standards Specification 1752 Laboratory Sintered or Fritted Filters). Variations of the three parameters to give the required contact period for different quantities of tobacco with diflerent sizes of equipment can be calculated.

The efiluent liquid from the extraction was immediately frozen by being cooled to about 50 C., at which tem perature substantially all the material extracted remains involatile and chemically inert. The water was then removed by freeze-drying carried out with the frozen efiluent at -50 C., .a drying chamber temperature of 28 to 40 C., preferably 35 C., and a pressure decrease until the temperature of the residue attained the temperature of the drying chamber. At this temperature, the dried residue was substantially stable chemically. 19 parts of a fine, pale-brown, powder were produced.

The two temperatures, 50 C. and +35 C., were chosen to ensure not only that the extracted material remained virtually constant in its chemical composition during processing, but also to give a reasonable value for the water-vapour pressure over the icy mixture during processing and to avoid an unduly long processing time.

Pulverisation of the product of the freeze-drying process under the conditions specified was unnecessary, but if the frozen effluent had a higher concentration of extracted material, a highly friable flake may be produced which would require pulverisation.

(b) The powder produced in the above-described manner was dusted evenly onto a blend of cut tobacco rag of high quality to give an addition of 5% by weight of the powder to the original weight of the cut tobacco. The material so obtained was made into cigarettes and was smoked by a panel of smokers in comparison with cigarettes made from untreated similar tobacco. A majority of the panel noticed a marked enhancement of the flavour characteristics of the smoke from the treated cigarettes.

Example 2 Powder produced as in Example 1(a) was dusted evenly onto a blend of cut tobacco rag of low quality to give an addition of 5% by weight of the powder to the original weight of the cut tobacco. Cigarettes made from this material were smoked by a panel of smokers in comparison with cigarettes made from untreated simi- A marked improvement and enhancement from the treated cigarettes r tobacco.

the flavour of the smoke as noticed.

Example 3 an aromatic Burley tobacco were (a) 100 part of 21 parts of a fine Example 4 Using the powder produced in accordance with Examle 3(a), the procedure described in Example 2 was caried out. A panel of smokers noticed a marked improveient of the flavour of the smoke from the cigarettes nade from the treated tobacco.

We claim:

1. A method of treating tobacco comprising preparng a bed of ground tobacco disposed on a filtering means laving a porosity such that a solvent passing through the 16d is controlled at a sufiicient rate so as to obviate subitantially decomposition of the more unstable tobacco iroma and flavor constituents contained in the liquor; :xtracting the ground tobacco with an ice-cold solvent 9y percolation of the solvent through the bed of tobacco; rapidly freezing the liquor by subjecting the liquor to a temperature substantially below the freezing point of the solvent so that all of the material extracted remains substantially involatile and chemically inert and then freeze drying the frozen liquor by subjecting the frozen liquor to reduced pressures while maintaining the liquor in a frozen state until the flavor and aroma constituents extracted from the tobacco are free of solvent.

2. A method as claimed in claim 1, wherein the solvent is ice-cold water.

3. A method as claimed in claim 1, wherein the tobacco is reduced to about Ms inch particle size and is extracted with ice-cold water, using 6 parts by weight of water to each part of tobacco, by percolating the water through the tobacco, supported as a bed on a filter screen, at a rate of about 5 ml./ per minute, the percolated liquor being rapidly frozen and the water removed by freeze drying.

4. A method of treating tobacco as set forth in claim 1 wherein the freeze dried flavor and aroma constituents are added to a smoking tobacco in a proportion up to 10% of the freeze dried material based on the weight of the smoking tobacco.

5. A method of preparing an improved flavor and aroma tobacco smoking product comprising preparing a bed of ground tobacco disposed on a filtering means having a porosity such that a solvent passing through the bed is controlled at a sufficient rate so as to obviate substantially decomposition of the more unstable tobacco aroma and flavor constituents contained in the liquor; extracting the ground tobacco with an ice-cold solvent by percolation of the solvent through the bed of tobacco; rapidly freezing the liquor by subjecting the liquor to a temperature substantially below the freezing point of the solvent so that all of the material extracted remains substantially involatile and chemically inert and then freeze drying the frozen liquor by subjecting the frozen liquor to reduce pressures while maintaining the liquor in a frozen state until the flavor and aroma constituents extracted from the tobacco are free of solvent, and then adding the freeze dried flavor and aroma constituents to smoking tobacco in a proportion up to 10% by weight of the aroma material based on the weight of smoking tobacco and then forming a smoking tobacco product.

6. A method as claimed in claim 5, wherein the said product, in the form of a fine powder, is dusted upon the said smoking tobacco.

7. A method as claimed in claim 5, wherein the said product is added in a proportion of about 5% of the said smoking tobacco.

8. A smoking tobacco product made by the method of claim 5.

References Cited by the Examiner UNITED STATES PATENTS 720,830 2/1903 Marsden 131143 1,016,844 2/ 1912 Moonelis 131143 X 2,783,149 2/ 1957 Epstein 99-7l FOREIGN PATENTS 832,991 4/ 1960 Great Britain.

910,451 11/1962 Great Britain.

SAMUEL KOREN, Primary Examiner.

MELVIN D. REIN, Examiner.

Claims (1)

1. A METHOD OF TREATING TOBACCO COMPRISING PREPARING A BED OF GROUND TOBACCO DISPOSED ON A FILTERING MEANS HAVING A POROSITY SUCH THAT A SOLVENT PASSING THROUGH THE BED IS CONTROLLED AT A SUFFICIENT RATE SO AS TO OBVIATE SUBSTANTIALLY DECOMPOSITION OF THE MORE UNSTABLE TOBACCO AROMA AND FLAVOR CONSTITUENTS CONTAINED IN THE LIQUOR; EXTRACTING THE GROUND TOBACCO WITH AN ICE-COLD SOLVENT BY PERCOLATION OF THE SOLVENT THROUGH THE BED OF TOBACCO; RAPIDLY FREEZING THE LIQUOR BY SUBJECTING THE LIQUOR TO A TEMPERATURE SUBSTANTIALLY BELOW THE FREEZING POINT OF THE SOLVENT SO THAT ALL THE MATERIAL EXTRACTED REMAINS SUBSTANTIALLY INVOLATILE AND CHEMICALLY INERT AND THEN FREEZE DRYING THE FROZEN LIQUOR BY SUBJECTING THE FROZEN LIQUOR TO REDUCED PRESSURES WHILE MAINTAINING THE LIQUOR IN A FROZEN STATE UNTIL THE FLAVOR AND AROMA CONSTITUENTS EXTRACTED FROM THE TOBACCO ARE FREE OF SOLVENT.