U.S. patent application number 14/025550 was filed with the patent office on 2014-01-16 for method of manufacturing reconstituted tobacco material and apparatus.
This patent application is currently assigned to JAPAN TOBACCO INC.. The applicant listed for this patent is JAPAN TOBACCO INC.. Invention is credited to Tsuyoshi FUTAMURA, Norio KAWATA, Yoshiyuki YAMADA.
Application Number | 20140014123 14/025550 |
Document ID | / |
Family ID | 46830190 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140014123 |
Kind Code |
A1 |
FUTAMURA; Tsuyoshi ; et
al. |
January 16, 2014 |
METHOD OF MANUFACTURING RECONSTITUTED TOBACCO MATERIAL AND
APPARATUS
Abstract
A reconstituted tobacco material is manufactured by extracting a
natural tobacco material with an extracting solvent to obtain an
extraction residue and a tobacco extracted liquid containing
desired components and undesired components including
tobacco-specific nitrosamines, subjecting the tobacco extracted
liquid to a fractionating treatment by means of a reverse osmosis
membrane to obtain a membrane impermeable fraction containing the
desired components and depleted in the undesired components and a
membrane permeable fraction depleted in the desired components and
enriched in the undesired components, controlling the tobacco
extracted liquid during the fractionating treatment to have a
temperature suitable for the fractionating treatment, removing
precipitates, which are precipitated in the tobacco extracted
liquid during the fractionating treatment, from the tobacco
extracted liquid, preparing a reconstituted tobacco web containing
the extraction residue, and adding the membrane impermeable
fraction to the reconstituted tobacco web.
Inventors: |
FUTAMURA; Tsuyoshi; (Tokyo,
JP) ; KAWATA; Norio; (Tokyo, JP) ; YAMADA;
Yoshiyuki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JAPAN TOBACCO INC. |
Tokyo |
|
JP |
|
|
Assignee: |
JAPAN TOBACCO INC.
Tokyo
JP
|
Family ID: |
46830190 |
Appl. No.: |
14/025550 |
Filed: |
September 12, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/056077 |
Mar 15, 2011 |
|
|
|
14025550 |
|
|
|
|
Current U.S.
Class: |
131/297 |
Current CPC
Class: |
A24B 15/12 20130101;
A24B 15/24 20130101; A24B 15/245 20130101 |
Class at
Publication: |
131/297 |
International
Class: |
A24B 15/24 20060101
A24B015/24 |
Claims
1. A method of manufacturing a reconstituted tobacco material,
comprising: (a) extracting a natural tobacco material with an
extracting solvent to obtain an extraction residue and a tobacco
extracted liquid containing desired components and undesired
components including tobacco-specific nitrosamines; (b) subjecting
the tobacco extracted liquid to a fractionating treatment by means
of a reverse osmosis membrane to obtain a membrane impermeable
fraction containing the desired components and depleted in the
undesired components and a membrane permeable fraction depleted in
the desired components and enriched in the undesired components;
(c) controlling the tobacco extracted liquid during the
fractionating treatment to have a temperature suitable for the
fractionating treatment; (d) removing precipitates, which are
precipitated in the tobacco extracted liquid during the
fractionating treatment, from the tobacco extracted liquid; (e)
preparing a reconstituted tobacco web containing the extraction
residue; and (f) adding the membrane impermeable fraction to the
reconstituted tobacco web.
2. The method according to claim 1, wherein in tobacco extracted
liquid is controlled to have a temperature within a range of 40 to
80.degree. C. in the step (c).
3. The method according to claim 1, wherein the step (b) comprises:
repeatedly performing the fractionating treatment to obtain a
concentrated membrane impermeable fraction, and repeating a cycle
of consisting of addition of process water to the concentrated
membrane impermeable fraction and the fractionating treatment of
the membrane impermeable fraction supplied with the process
water.
4. The method according to claim 3, wherein the cycle is repeated
until a membrane impermeable fraction, from which the
tobacco-specific nitrosamines contained in the tobacco extracted
liquid obtained in the step (a) is removed by 60 wt % or more of
its initial amount, is obtained.
5. The method according to claim 1, wherein the step (c) is
performed by using a filter having a pore size of 3 .mu.m or
less.
6. The method according to claim 3, wherein the process water is
obtained by removing bicarbonate ions from hard water containing
bicarbonate ions.
7. A fractionating apparatus for separating desired components from
tobacco-specific nitrosamine-including undesired components in a
tobacco extracted liquid, comprising: a process vessel which
contains the tobacco extracted liquid; a fractionating device
comprising a reverse osmosis membrane by which the tobacco
extracted liquid is fractionated into a membrane impermeable
fraction containing the desired components and depleted in the
undesired components and a membrane permeable fraction depleted in
the desired components and enriched in the undesired components; a
pump which feeds the tobacco extracted liquid to the fractionating
device under pressure; a filter for removing precipitates such as
protein which are precipitated in the tobacco extracted liquid
during the fractionating treatment; and a temperature controlling
device which controls the tobacco extracted liquid to have a
temperature suitable for the fractionating treatment during the
fractionating treatment.
8. The apparatus according to claim 7, wherein the temperature
controlling device controls the tobacco extracted liquid to have a
temperature within a range of 40 to 80.degree. C.
9. The apparatus according to claim 7, wherein the temperature
controlling device is constituted of a heat exchanger.
10. The apparatus according to claim 7, further comprising: an
ultrafiltration device which comprises ultrafiltration membrane for
removing bicarbonate ions from hard water containing bicarbonate
ions, and is configured to provide bicarbonate ion-removed water as
process water.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation Application of PCT
Application No. PCT/JP2011/056077, filed Mar. 15, 2011, the entire
contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of manufacturing a
reconstituted tobacco material, and an apparatus used in the
method.
[0004] 2. Description of the Related Art
[0005] Various components such as nicotine, nitrates, nitrosamines,
hydrocarbons and proteins are contained in tobacco materials such
as the leaf, shreds, stem, stalk, and root of natural tobacco
plants. These components are extracted from natural tobacco
materials and are used as a smoking flavor additive to tobacco.
These components include those which are desirable to be decreased
in amount or to be removed (undesired components), and also include
those which are desirable not to be removed or to be increased in
amount (desired components), in view of the smoking flavor or some
other reasons. The desired components include amino acids, sugars,
nicotine, leaf surface resins, and alkaloids. The undesired
components include nitrates, and nitrosamines such as
tobacco-specific nitrosamines (TSNAs).
[0006] Patent Document 1 discloses a method of manufacturing a
regenerated tobacco material. The method comprises extracting a
natural tobacco material to obtain an extracted solution and an
extraction residue, and subjecting the extracted solution to
fractionating treatment by means of ultrafiltration or reverse
osmosis filtration or fractionating treatment by means of
reversed-phase partition chromatography to obtain a first fraction
enriched in the desired components and depleted in the undesired
components and a second fraction enriched in the undesired
components and depleted in the desired components. The regenerated
tobacco material is manufactured by preparing a regenerated tobacco
web from the extraction residue and adding the first fraction to
the regenerated tobacco web.
[0007] Patent Document 1 discloses that since the first fraction
(membrane impermeable fraction) obtained by fractionating treatment
by means of ultrafiltration or reverse osmosis filtration may
contain nitrosamines such as TSNAs, it is desirable to subject the
membrane impermeable fraction to an additional treatment so as to
remove nitrosamines before the membrane impermeable fraction is
added to the regenerated tobacco web.
PRIOR ART DOCUMENT
Patent Document
[0008] Patent Document 1: U.S. Pat. No. 7,677,253
BRIEF SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0009] An object of the present invention is to provide a method of
manufacturing a reconstituted tobacco material which contains
desired components of a significant amount and undesired components
including TSNAs with a significantly reduced amount, by achieving
practical separation of desired components and undesired components
including TSNAs by means of a reverse osmosis membrane.
[0010] In addition, an object of the present invention is to
provide an apparatus for obtaining, from a tobacco extracted
liquid, a fraction which contains desired components of a
significant amount, and from which undesired components including
TSNAs are removed by a significant amount, by means of a reverse
osmosis membrane.
Means for Solving the Problem
[0011] According to one aspect of the present invention, there is
provided a method of manufacturing a reconstituted tobacco
material, comprising: (a) extracting a natural tobacco material
with an extracting solvent to obtain an extraction residue and a
tobacco extracted liquid containing desired components and
undesired components including TSNA; (b) subjecting the tobacco
extracted liquid to a fractionating treatment by means of a reverse
osmosis membrane to obtain a membrane impermeable fraction
containing the desired components and depleted in the undesired
components and a membrane permeable fraction depleted in the
desired components and enriched in the undesired components; (c)
controlling the tobacco extracted liquid during the fractionating
treatment to have a temperature suitable for the fractionating
treatment (generally, a temperature within a range of 40 to
80.degree. C); (d) removing precipitates, which are precipitated in
the tobacco extracted liquid during the fractionating treatment,
from the tobacco extracted liquid; (e) preparing a reconstituted
tobacco web containing the extraction residue; and (f) adding the
membrane impermeable fraction to the reconstituted tobacco web.
[0012] According to another aspect of the present invention, there
is provided a fractionating apparatus for separating desired
components from TSNA-including undesired components in a tobacco
extracted liquid, comprising: a process vessel which contains the
tobacco extracted liquid; a fractionating device comprising a
reverse osmosis membrane by which the tobacco extracted liquid is
fractionated into a membrane impermeable fraction containing the
desired components and depleted in the undesired components and a
membrane permeable fraction depleted in the desired components and
enriched in the undesired components; a pump which feeds the
tobacco extracted liquid to the fractionating device under
pressure; a filter for removing precipitates such as protein which
are precipitated in the tobacco extracted liquid during the
fractionating treatment; and a temperature controlling device which
controls the tobacco extracted liquid to have a temperature
suitable for the fractionating treatment during the fractionating
treatment (generally, a temperature within a range of 40 to
80.degree. C).
Effects of the Invention
[0013] According to the present invention, it is possible to
manufacture a reconstituted tobacco material which contains desired
components of a significant amount and undesired components
including TSNAs with a significantly reduced amount, by achieving
practical separation of desired components and undesired components
in a tobacco extracted liquid by means of a reverse osmosis
membrane.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0014] The single FIGURE is a schematic diagram of a fractionating
apparatus according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] An aspect of the present invention relates to a method of
manufacturing a reconstituted tobacco material by using a tobacco
extracted liquid and an extraction residue which are obtained by
extracting a natural tobacco material. On one hand, a reconstituted
tobacco web containing the extraction residue is manufactured. On
the other hand, the tobacco extracted liquid is subjected to
fractionating treatment by means of a reverse osmosis membrane. The
fractionating treatment produces a membrane impermeable fraction
which contains desired components and is depleted in undesired
components including TSNAs, and a membrane permeable fraction which
is depleted in the desired components and enriched in the undesired
components including TSNAs. A desired reconstituted tobacco
material is manufactured by adding the membrane impermeable
fraction to the reconstituted tobacco web. The membrane permeable
fraction is discarded.
[0016] More specifically, first, natural tobacco material is mixed
with an extracting solvent, and the mixture is stirred. As the
natural tobacco material, tobacco leaf, shreds, stem, stalk, and
root, and a mixture thereof may be used. As the extracting solvent,
water, or a mixture of water and a water-miscible organic solvent
may be used. Examples of the water-miscible organic solvent include
alcohols such as ethanol, and ethers such as diethyl ether. In
general, the extracting treatment is carried out at a temperature
of 0 to 100.degree. C. for 5 minutes to 6 hours.
[0017] After completion of the extracting treatment, the extracted
mixture obtained is subjected to separating treatment by, for
example, filtration or centrifugation to separate the extracted
mixture into a tobacco extracted liquid and an extraction
residue.
[0018] The natural tobacco material contains salts of metals such
as potassium salt, nitrates, nicotine, sugars such as sucrose,
amino acids, glycosides, amino-sugar compounds, proteins,
hydrocarbons (saturated hydrocarbons, unsaturated hydrocarbons,
aromatic hydrocarbons), alcohols, ethers, aldehydes, ketones,
esters, lactones, quinones, acids (including acid anhyrides),
phenols, amines, pyrroles, pyridines, pyrazines, alkaloids,
polycyclic nitrogen-containing compounds, nitroso compounds such as
nitrosamines (including TSNAs), amides, lipids, halides,
sulfur-containing compounds, and inorganic elements. The tobacco
extracted liquid obtained by the above extracting treatment can
contain substantially all of the components mentioned above, though
depending on the type of the extracting solvent used. Of these
components, the desired components include amino acids, sugars,
nicotine, leaf surface resins, and alkaloids, and the undesired
components include nitrates and nitrosamines such as TSNAs. Typical
examples of TSNAs are nitrosamines (N'-nitrosonornicotine (NNN),
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK),
N'-nitrosoanatabine (NAT), and N'-nitrosoanabasine (NAB)).
According to the present invention, nicotine and TSNAs which are
similar in the chemical structures can be effectively separated
from each other by a reverse osmosis membrane.
[0019] The extraction residue is a component insoluble in the
extracting solvent and consists essentially of fibers. A
reconstituted tobacco web is manufactured by an ordinary method by
using the extraction residue. The extraction residue may constitute
the entire reconstituted tobacco web or a part of the reconstituted
tobacco web. For example, a reconstituted tobacco web can be
obtained by subjecting pulp material containing the extraction
residue to an ordinary paper-making process.
[0020] On the other hand, the tobacco extracted liquid is contained
in a process vessel and fed to a reverse osmosis membrane under
pressure. The reverse osmosis membrane fractionates the tobacco
extracted liquid into a membrane permeable fraction and a membrane
impermeable fraction. The membrane permeable fraction is enriched
in undesired components including TSNAs. Correspondingly, the
membrane impermeable fraction is depleted in the undesired
components including TSNAs. In the membrane impermeable fraction,
the initial amount of desired components (such as nicotine) in the
tobacco extracted liquid is substantially maintained (85 wt % or
more). Correspondingly, the membrane permeable fraction
substantially contains no desired components.
[0021] The reverse osmosis membrane is a membrane which is
permeable to the undesired components, and substantially
impermeable to the desired components. The reverse osmosis membrane
is preferably impermeable to soluble components (excluding TSNAs),
such as sugar, contained in the tobacco extracted liquid. A reverse
osmosis membrane having a pore size of 0.1 to 3 nm may be used. The
reverse osmosis membrane may be a flat sheet membrane, a membrane
obtained by forming a bag-shaped membrane into a tubular shape
(spiral membrane), or a hollow fiber membrane or a tubular
membrane. The tobacco extracted liquid can be supplied to the
reverse osmosis membrane under a pressure of, for example, 1 to 3
MPa. The membrane permeable fraction is discarded. Supply of the
tobacco extracted liquid to the reverse osmosis membrane can be
performed by using a high-pressure pump.
[0022] During the fractionating treatment, the tobacco extracted
liquid is sent under high pressure by the high-pressure pump, and
thus the temperature of the tobacco extracted liquid rises.
Therefore, in order to efficiently perform the fractionating
treatment by means of the reverse osmosis membrane, the tobacco
extracted liquid is controlled to fall within a temperature of
generally 40 to 80.degree. C. (generally by cooling) during the
fractionating treatment. Further, precipitates such as protein are
precipitated in the tobacco extracted liquid because the tobacco
extracted liquid reaches a relatively high temperature during the
fractionating treatment, and thus the precipitates are removed. To
remove the precipitates such as protein from the tobacco extracted
liquid, the tobacco extracted liquid is made to pass through a
filter. Since the precipitates such as protein have a diameter of 3
.mu.m or more, a metal filter having a pore size of 3 .mu.m or less
can be used as the filter. The pore size of the filter is generally
1.8 .mu.m or more. The precipitates, when not removed, decrease the
fractionation efficiency of the reverse osmosis membrane, and makes
the reverse osmosis membrane inoperative in the end. Since fine
suspended matter may exist in the tobacco extracted liquid as
extracted, the tobacco extracted liquid is preferably made to pass
through a filter to remove the fine suspended matter in advance.
The tobacco extracted liquid which is initially contained in the
process vessel may have a temperature within a range of 40 to
80.degree. C.
[0023] In an embodiment, in order to improve the treatment
efficiency, the membrane impermeable fraction can be concentrated
by repeating a cycle of returning the membrane impermeable fraction
to the process vessel and then subjecting the membrane impermeable
fraction to the membrane fractionating treatment.
[0024] The membrane impermeable fraction concentrated as described
above is supplied with process water in the process vessel, in
order to improve the fractionation efficiency by means of the
reverse osmosis membrane. The membrane impermeable fraction, to
which the process water has been added, is subjected to the
membrane fractionating treatment, and then the obtained membrane
impermeable fraction is returned to the process vessel. The cycle
consisting of addition of the process water, membrane fractionating
treatment, and return of the membrane impermeable fraction to the
process vessel is repeated until the TSNA amount in the membrane
impermeable fraction is reduced to, for example, approximately 40
wt % or less of the initial amount (TSNA removal rate is 60 wt % or
more), 20 wt % or less of the initial amount (TSNA removal rate is
80 wt % or more), or 10 wt % or less of the initial amount (TSNA
removal rate is 90 wt % or more). The desired components (for
example, nicotine) can be maintained at 85 wt % or more of the
inital amount.
[0025] In the meantime, the process water preferably contains no
nicarbonate ions. It has been found that when process water
containing bicarbonate ions is used, the fractionating treatment
needs more time. Thus, it is preferable to use soft water
containing no bicarbonate ions as the process water. When hard
water containing bicarbonate ions is used as the process water, it
is preferable to remove bicarbonate ions in advance by, for
example, an ultrafiltration membrane.
[0026] The above fractionating treatment can be executed by means
of a fractionating apparatus for separating desired components from
TSNA-including undesired components in the tobacco extracted
liquid, the fractionating apparatus comprising: a process vessel
which contains the tobacco extracted liquid, a fractionating device
comprising a reverse osmosis membrane by which the tobacco
extracted liquid is fractionated into a membrane impermeable
fraction containing the desired components and depleted in the
undesired components and a membrane permeable fraction enriched in
the undesired components, a pump which feeds the tobacco extracted
liquid to the fractionating device under pressure, a filter for
removing precipitates such as protein which are precipitated in the
tobacco extracted liquid during the fractionating treatment, and a
temperature controlling device which controls the tobacco extracted
liquid to have a temperature suitable for the fractionating
treatment (generally, a temperature within a range of 40 to
80.degree. C.) during the fractionating treatment.
[0027] FIG. 1 is a schematic diagram illustrating a structure of
the above apparatus. A fractionating apparatus 100 illustrated in
FIG. 1 comprises a process vessel 110 which contains the tobacco
extracted liquid. The process vessel 110 communicates with a
high-pressure pump 130 by a line L1, and the high-pressure pump 130
communicates with a fractionating device 140 comprising a reverse
osmosis membrane 141 by a line L2. The fractionating device 140
communicates with the process vessel 110 by a line L3. The
fractionating device 140 has a discard line L4 for discarding a
membrane permeable fraction. The line L1 is provided with a filter
120 for removing precipitates such as protein which are
precipitated in the tobacco extracted liquid, wherein the
precipitates are increased by repeated fractionating treatments of
the tobacco extracted liquid by means of the fractionating device
140. As described above, the filter 120 has pores of 3 .mu.m in
order to prevent precipitates such as protein precipitated in the
tobacco extracted liquid from passing through the filter 120. The
line L3 is provided with a heat exchanger 150 serving as a
temperature controlling device which controls and maintains a
temperature of the tobacco extracted liquid within a range of 40 to
80.degree. C., wherein the temperature of the tobacco extracted
liquid rises during the repeated fractionating treatments. For
example, the heat exchanger 15 can be a device which introduces
cooling water into a part around the line L3 from a line L5, and
discharges the water after heat exchange from a line L6.
[0028] The tobacco extracted liquid obtained by the above
extracting treatment can be stored in a storage vessel 160. The
tobacco extracted liquid contained in the storage vessel 160 may be
stored at low temperature (of 10 to 20.degree. C.) in order to
prevent decomposition.
[0029] One batch of tobacco extracted liquid TEL is supplied to the
process vessel 110 from the storage vessel 160 through a line L7.
Then, the tobacco extracted liquid contained in the process vessel
110 is fed from the process vessel 110 to the fractionating device
140 through the filter 120 by drive of the high-pressure pump 130.
In the fractionating device 140, the tobacco extracted liquid is
fractionated into a membrane permeable fraction which is depleted
in the desired components and enriched in the undesired components
including TSNAs, and a membrane impermeable fraction which is
depleted in the undesired components including TSNAs and containing
the desired components, by means of the reverse osmosis membrane
141 of the fractionating device 140. The membrane permeable
fraction is discarded from the fractionating device 140 through the
line L4.
[0030] The membrane impermeable fraction is returned to the process
vessel 110 through the line L3. The membrane impermeable fraction
which has been returned to the process vessel 110 is supplied again
to the fractionating device 150 by the high-pressure pump 130
through the lines L1 and L2, and fractionated into a membrane
permeable fraction and a membrane impermeable fraction. The
membrane impermeable fraction can be returned to the process vessel
110 through the line L3. Needless to say, the membrane permeable
fraction is discarded each time through the line L4.
[0031] When the membrane impermeable fraction is concentrated by
repeated fractionating treatments as described above, process water
is added from a water vessel 170 to the membrane impermeable
fraction contained in the process vessel 110 through a line L8, in
order to prevent decrease in efficiency of the fractionating
treatment by means of the reverse osmosis membrane. The line L8 may
be provided with an ultrafiltration device 180 comprising an
ultrafiltration membrane 181, in order to remove bicarbonate ions
in the case where the water is hard water containing bicarbonate
ions. A filtrate (bicarbonate ion-removed water) derived from the
ultrafiltration device 180 is added as the process water to the
process vessel 110 through the line L8. The membrane impermeable
fraction to which the process water has been added is repeatedly
subjected to the fractionating treatment until the amount of TSNAs
in the fraction is reduced to, for example, approximately 40 wt %
or less, 20 wt % or less, or 10 wt % or less, of the initial amount
thereof. The amount (volume) of the membrane impermeable fraction
containing the process water is the same as the amount (volume) of
the added process water. During the concentration and the repeated
cycle of water addition and fractionating treatment, the tobacco
extracted liquid (the concentrated tobacco extracted liquid and the
tobacco extracted liquid containing the process water) is cooled to
a temperature of 40 to 80.degree. C. by the heat exchanger 150, and
maintained at the temperature, and precipitates such as protein are
removed from the tobacco extracted liquid by the filter 120. The
amount of the undesired components, such as TSNAs, in the membrane
impermeable fraction can be determined by measuring the amount of
the desired components or the undesired components contained in the
membrane permeable fraction discharged from the line L4. The
temperature of the tobacco extracted liquid can be monitored by a
temperature sensor 180, which is provided on the line L2 and close
to the fractionating device 141.
[0032] In the above embodiment, although the filter 120 is provided
(on the line L1) between the process vessel 110 and the
high-pressure pump 130, a similar filter 120' may be provided on
the line L3 between the fractionating device 140 and the heat
exchanger 150, and/or a similar filter 120 may be provided on the
line L3 between the heat exchanger 150 and the process vessel 110,
instead of or in addition to the filter 120, as indicated by broken
lines in FIG. 1. In addition, as indicated by broken lines in FIG.
1, the process vessel 110 may be externally provided with a line L9
to circulate the tobacco extracted liquid contained in the process
vessel 110, and the line L9 may be provided with a similar filter
120'''. To provide a filter (on the line L2) between the
high-pressure pump 110 and the fractionating device 140, however,
is not preferable, because precipitates such as protein which have
been captured by the filter, undesirably pass through the pores of
the filter by the tobacco extracted liquid which is pumped under
high pressure by the high-pressure pump 130 and have adverse
influence on the fractionating treatment.
EXAMPLES
[0033] The present invention will be explained hereinafter by
examples, but the present invention is not limited by them.
Example 1
[0034] In the present Example, fractionating treatment was
performed by using the apparatus illustrated in FIG. 1. Duratherm
Excel R0 4040HR manufactured by GE Water Technologies was used as
the reverse osmosis membrane.
[0035] First, 10 kg of tobacco scraps consisting of a mixture of
tobacco leaf scraps (mixture of flue-cured type and Burley type)
and stem scraps was mixed with 50 L of water at a temperature of
60.degree. C., and stirred to perform extraction of tobacco shreds.
The extracted mixture obtained was filtered to be separated into
tobacco extracted liquid and extraction residue. The concentration
of TSNAs (sum of NNN, NNK, NAT, and NAB) in the tobacco extracted
liquid was measured by chromatography. The concentration was 424
mg/m.sup.3.
[0036] The extraction residue was subjected to paper-making
process, and thereby a reconstituted tobacco web was obtained. On
the other hand, the tobacco extracted liquid was stored in the
storage vessel 160.
[0037] Next, 33.5 L of tobacco extracted liquid was introduced into
the process vessel 110 from the storage vessel 160. By driving the
high-pressure pump 130 (which feeds the tobacco extracted liquid
under a pressure of 2 MPa), the tobacco extracted liquid was
supplied to the reverse osmosis membrane 141 through the filter 120
(stainless steel filter having a pore size of 3 .mu.m). A membrane
impermeable fraction was returned to the process vessel 110. The
membrane impermeable fraction which has been returned to the
process vessel 110 was repeatedly subjected to the above
fractionation cycle, until the amount of the membrane impermeable
fraction was reduced to 18 L.
[0038] 1 L of water (process water), from which bicarbonate ions
have been removed in advance by means of the ultrafiltration
membrane 181, was added to the 18 L of concentrated membrane
impermeable fraction in the process vessel 110, and membrane
fractionating treatment was performed in a similar manner. The
membrane impermeable fraction was returned to the process vessel
110, 1 L of water, from which bicarbonate ions have been removed in
advance, was added to the membrane impermeable fraction again, and
the membrane impermeable fraction was returned to the process
vessel 110. Addition of the process water and fractionating
treatment were repeated until the total amount of the added process
water reached 133 L, and thereby a desired (final) membrane
impermeable fraction was obtained (it took approximately one hour
since concentration was started). During the fractionating
treatments, the tobacco extracted liquid was maintained at
approximately 60.degree. C., and precipitates such as protein were
removed by the filter 120. The amount of TSNAs in the obtained
membrane impermeable fraction was 4.5% of the initial amount
thereof (removal rate of 95.5%), and nicotine was maintained at
approximately 86.6% of the initial amount thereof. The membrane
impermeable fraction obtained as described above was added to the
reconstituted tobacco web, and thereby a reconstituted tobacco
material was obtained.
Example 2
[0039] Example 2 was performed in the same procedure as Example 1,
except that hard water, from which bicarbonate ions were not
removed, was used without any treatment as the process water. In
the present case, 133 L of hard water in total was added in order
to obtain a final membrane impermeable fraction having the same
TSNA removal rate and nicotine maintenance rate as those of Example
1. Approximately 80 minutes was required to obtain the final
membrane impermeable fraction since concentration was started.
* * * * *