US3540455A - Reconstituted tobacco sheet and method of making same - Google Patents

Description

United States Patent [72] Inventors Joseph Vincent Fiore [56] References Cited F airfield, and UNITED STATES PATENTS 2" 802,487 10/1905 Wimmer 131/143 [211 P 967 1,294,310 2/1919 Sayre m1. 131/143 fi f ted 1 2,293,954 8/1942 Tiger et a1.... 131/143ux 3 999,986 8/1911 Giordano 131/17 1 Asslghee America" Machmes f'" CmnPW 3,297,039 1/1967 Osborne et a1... 131/140x 3,420,241 1/1969 Hind eta]. 131/140 Fri/nary ExaminerMelvin D. Rein RECONSTITUTED TOBACCO SHEET AND A ttorney- George W. Price and Murray Schaffer METHOD OF MAKING SAME 2 C|8im5N Drawings ABSTRACT: Herein is disclosed a process for the treatment 52 US. (11...; 131/17, of tobacco in the manufacture of reeehstiwted tehaeee 131/143 products. In the method described a water-tobacco slurry is 511 1111. c1 A241) 03/14, produced and thereafter at least a portion of the pelyphehel 241, 15 00 constituent of the extract is precipitated or neutralized by 501 Field ofSearch 131/140-144, treatment with sodium Sulphate the extent of one 19 five parts per hundred parts of tobacco, by weight.

RECONSTITUTED TOBACCO SHEET AND METHOD OF MAKING SAME The present invention relates to a method for the preparation of reconstituted tobacco sheet and more particularly to an improved process for preparing light-colored reconstituted tobacco sheet, despite the use of heat as a processing aid at any stage of the process. I

The commercial method for the manufacture of reconstituted tobacco sheet requires the application'of heat to the material at some stage in the processing, i.e. either in the preparative stages and/or in the drying. It is known that the color of the finished tobacco product darkens because of the heating; the level of darkening being a function of temperature and heating time. As a rule, it is desirable to produce a light-colored tobacco sheet and various steps are taken to achieve this goal, for example the addition of dyes or coloring chemicals, the addition of color-masking agents whiteners such as titanium dioxide, control of temperature and heating time. These steps are never completely satisfactory because of the limitations under which they can be applied. In the case of the addition of dying, coloring and masking chemicals the introduction of extraneous material can be undesirable, especially if excessive amounts are needed to produce the desired results.- Excessive use of dyes can produce leaching problems while excessive use of whiteners can result in sheets which are greyish in appearance or lack proper physical structure. In the case of controlled temperature and heating time, undesirable limitations are-put upon the manufacturing procedures. The invention revealed herein makes it possible to produce a light-colored, reconstituted tobacco sheet without the resort-to dyes or masking agents for color preservation and without any undue limitations on the temperature and heating time used in the process. This is achieved by selectively removing or neutralizing the specific agents responsible for the darkening of the tobacco on heating.

In the preparation of additive reconstituted tobacco, tobac co such as stems, field scrap cuttings, whole leaf and the like is preferably uniformly comminuted and formed into tobacco sheet suitable for later machine processing. On the other hand, in the preparation of all tobacco reconstituted sheet or in reconstituted sheets wherein'a more efficient utilization of the natural gums of the tobacco is desired, the tobacco is usually ground to colloid-forming size particles by a wet process or refining. However, the large amount of energy and time required for the preparation of these colloid-forming size tobacco particles has limited its use for the preparation of reconstituted sheets.

To reduce the energy expended and time involved to comminute the tobacco particles in the wet process, it is desirable to cook the tobacco prior to refining. This cooking operation reduces the refining time and simultaneously improves the physical properties of the finished product. However, the cooking causes darkening of the tobacco material, thereby making such sheets unacceptable in a number of manufactured tobacco products.

We have now found what we believe to be the specific agents causing the darkening of the tobacco upon heating and propose as the prime object ofthis invention the control of color by selectively removing them or neutralizing them in situ.

The present invention also provides a solution to the longstanding problems in the processing of tobacco and results in a great reduction in energy and time required to obtain good quality reconstituted tobacco sheets of acceptable color.

A further object of the present invention is to provide a method for producing a light-colored reconstituted tobacco sheet despite the use of heat as a processing aid.

A still further object of the present inventionis to "neutralize polyphenols in the tobacco prior to exposure of'the tobacco-water mixture to heat in the preparation of recon:

stituted tobacco sheet.

An additional objective is to prepare a light-colored tobac'- c0 sheet without resort to dyes, coloring or masking agents.

Still another object of the present invention is to provide a method for accomplishing all of the above, which can be used in processing large quantities of tobacco resulting in a recon. stituted sheet of tobacco having an acceptable color and to do so in an economical and easily controllable method. I

Other objects and advantages of the present invention will be apparent from the further reading of the specification and v of the appended claims.

Tobacco as defined for this invention includes any type of tobacco suitable for the manufacture of reconstituted tobacco sheet, such as stems, veins, scrap and waste tobacco, cuttings and the like, as well as whole leaf or portions thereof.

in general the present invention discloses chemical methods for precipitating or neutralizing the agents responsible for the darkening of the tobacco when it is exposed to heat.

It has long been commonly believed that the agents responsible for the darkening of the tobacco on heating were the carbohydrates and the amino acids, which react during the heating to form dark-colored compounds, the process being called the .Maillard reaction. We have discovered that neither the 1 carbohydrates nor the amino acids darken the tobacco significantly on heating, but that polyphenols contained in the tobacco, especially the basic-polyphenols, do cause a significant darkening of the tobacco upon exposure to heating. This phenomenon is also pH dependent.

A series of tests were run to isolate and determine the agents which caused tobacco darkening upon heating. The fol- A still further object of the present invention is to remove lowing procedure illustrates how the polyphenols were identified as the agents which cause tobacco darkening during heating. A sample of Bright" stem dust weighing 10 gm. was mixed with ml. of distilled water. The slurry was filtered on a Buchner funnel using Whatman No. l filter paper. The filter cake and filtrate were retained. The filter cake was subsequently mixed with 90 ml. of a predetermined liquid and the slurry transferred to a vessel, such as a mason-jar, which was sealed and placed in a pressure cooker, where it was heated at 250F. at 15 p.s.i. for 2 hours. Upon cooling, three sheets having a thickness of about 0.25-0.30 mm. were cast from the slurry on 20 cm. X 20 cm. glass plates. The sheets were dried in an oven at l l0l 15C. for about IS- 20 minutes and the color of each sheet was determined in a Gardner automatic color difference meter (Model Ac-2A, Series 200). Readings were made by placing the plate over the Gardner aperture fwith the tobacco side facing the aperture. A number of readings were taken at different points on each plate, so as to obtain an overall average.

The test results in Table l were obtained with various additives in the predetermined liquid and serveto illustrate that polyphenols are the agents causing the darkening of the tobac:

' co on-exposure. to heat. Water-washed Bright stem dust was used in all cases, unless otherwise indicated. The weight of the washed tobacco in each sample was 7.0 gm. dry weight and this was suspended in 90 ml. of liquid prior to heating.

Thepolyphenol fractions shown in Table 1 were obtained as follows:

90 ml. of a tobacco-water extract, prepared as described above, was mixed with 20 ml. ofa 10 percent lead acetate solution, and the precipitate was removed by centrifugation. This precipitate comprised the acidic polyphenol fraction.

Adding more lead acetate solution to the supernatant caused no more precipitation. An alkaline reagent, such as ammonium hydroxide (NH Ol-l was added to the supernatant until the .pH was about 8.5-9.0. The precipitate, which was collected by centrifugation, constituted the basic-polyphenol fraction.

No'rE:

Rd=Brlghtness factor; b1ack=0; white=100. 2+; b+=Coord1dnates on a Chromatlclty Db agram. Pb Acetato=Lead acetate.

As seen from the experimental results shown in Table 1, the? basic polyphenols give a darker sheet than even the negative. controHRd readings 12.4 and 16.4, respectively). Further-' more, it is seen that while acidifying the basic'polyphenols im-. .proves the color, it is still far below the positive control (Rdl readings of 17.2 and 24.9, respectively). These results also: show that the sugars and amino acids do not affect the sheet color and-similarly neither does the lead acetate solution used; to precipitate the polyphenols.

Processes for the removal of the polyphenol fraction from tobacco by using adsorbent material are fully disclosed andi described in our copending U.S. Pat. application Ser. No.639,032 filed even date herewith. The present disclosure. Qconfines itself to the precipitation and neutralization" ofg polyphenols with chemical substances. 7 We have found that the interfering polyphenols can be inactivated fin situ" by sodium sulfite or removed from a water ex-- tract of tobacco by precipitation with chemical substances ofE ithe heavy metal salts such as lead acetate or barium acetate: While the above mentioned procedures (inactivation in situ" i or precipitation and removal) are entirely unacceptable in the manufacture of a 100 percent tobacco sheet (since they impart residuals to the tobacco materials) they are however. eminently suitable for the manufacture of non-100 percent 1 tobacco products.

The following examples are set forth to demonstrate the method of this invention.

Ten grams ofBright stem dust was mixed with 90 ml. ofa water solution containing various amounts of sodium sulfite. The mixtures were transferred to mason jars and treated as described in the early section of this disclosure. The obtained sheets were examined in the Gardner difference colorimeter in a manner described in an earlier part of this disclosure. The tobacco slurry. compositions and the color readings obtained on the prepared sheets are shown in Table 11.

TABLE 1.COLOR 0F SHEETS PREPARED FROM BRIGHT TABLE II STEM DUST HEATED IN SOLVENTS CONTAINING VARIOUS ADDITIVES Tobacfin Sodigtn W Hbetore H after 2 511 8 fil Materlals p heating heatlng Rd 2+ 5+ 5 sample Number (2 (em) (1111.) Rd a+ b+ wa 115a toba plus a e a Y 10.0 0.13 90.0 15.5 6.1 19.5 (pos1%v3gogtr bn unun 5.3 24.9 3.1 21.5 $8 8-28 33-8 g-g 3g @Zfiifffffff? 3.8 163 4 ativ c n r l)--- 1010 None 9010 1414 5Z9 1910 Washed tobacco plus Wa h. 10 5 (p control None 90.0 23.6 3.5 22.3 wlnlgls (iuegatlve cilmtrol) 4. 0 16. 4

?g3..f }ff??? 4 Wat washed tobacco 10 gm. Washedtobacco plus glucose 2 gm.) plus water 25. 2 Washed tobacco plus fructose (2 gm.) nz'lus wet/er 24.7 5 f fg ggg 5323 2; 2 2 1 It becomes apparent from the results in Table ll that the efeach) plus water I 7.2 26.8 fects of the polyphenols are neutralized by the addition of z fi i figzggg 1 5 5 2; ag sodium sulfite to the tobacco-water slurry.

Water 6, 3 22. 3 2.7 16.3 In the examples to follow. evidence is presented to show the figggggg z gf 22 L effects of removing the basic polyphenols. Ten grams of Bright plus water 6.1 22.9 2.5 17.3 20 stem dust was mixed with 90 ml. of water and filtered in a gifig ggg z gg 222%? Buchner funnel. The filtrate was mixed with 2 ml. of a satuplus water 6.1 22.2 3.3 17. 5 rated lead acetate solution, a precipitate formed. This gggg fgggggg gfgggg v precipitate, which comprised the acidic polyphenols, was plus water 6.1 22.0 2.5 17.1 removed b centrifu ation. The su ematant was brou ht to w h (It b 1 t t 25 y p g g i g gi g pH 9.0 by the addition of Nl-LOH. The precipitate, which Sucrose (1 each) plus comprised the basic polyphenols, was removed by centrifuga g fi -ag g g v 'g;" 2L9 tion and the supernatant was brought to an acidic pH (4.0- plus acidic polyphenols..." 5.2 4.5 22.0 3.5 I 16.3. -5.0) by the addition of an acid such as acetic, l-lCl, etc. g'gg gi g g igf glffffi 12 4 mo 30 Slurries were prepared from water washed tobacco and the Acldlfied basl c polyphenlols various polyphenolic fractions or. supernatants. The slurries egg ffft k ffkf ffjf 48 mg 4.7 were treated in a manner already described. The prepared Washed tobacco D1115 b acetate 23 4 sheets were examined for their color and the resultsas well as (10%) water f' the slurry compositions are presented in Table lll.

The polyphanol precipitates were obtained in a manner described in this disclosure.

2 Volume of acidified supernatant was 90 m1.

It is apparent from the FIGS. in Table III that the acidic polyphenols do not cause any darkening of the tobacco on heating. The use of acidified supernatant from which the basic polyphenols have been removed gives a sheet much lighter than theinegative control (Rd of 18.5 and 14.4 respectively). The basic polyphenolic fraction gives a sheet as dark as the negative control (Rd. 14.8 and 14.4 respectively). Very good results are achieved by neutralizing" the basic polyphenols with sodium sulfite' (Sample 5). In this case a sheet is obtained that is actuallyeven lighter than the positive control. (Rd 29.4 and 23.6 respectively). It has therefore been demonstrated that the darkening of tobacco on heating is caused, by basic polyphenols. This darkening can be avoided by adding to the tobacco areagent, such as sodium sultite, which neutralizes" the effectsof the darkening agents. The darkening can also be v avoided by' precipitating the basic polyphenols chemically and removing the precipitate.

We claim:

1. In the manufacture of reconstituted tobacco products,

I the process of preparing tobacco comprising the steps of treating such tobacco with water so as to'extract the water-soluble components of said tobacco including the polyphenols and "co so as to form a water-tobacco mixture including the extracted water soluble components of the original'tobacco. except for the polyphenols neutralized therefrom. I

2. A reconstituted tobacco product made by forming and subsequently drying a slurry of tobacco particles in which the tobacco is prepared in accordance with claim 1.