Note: Descriptions are shown in the official language in which they were submitted.
WO 2022/090497 -1-
PCT/EP2021/080181
NOVEL AEROSOL-GENERATING SUBSTRATE
The present invention relates to a novel aerosol-generating substrate
comprising dried
green tobacco material and to an aerosol-generating article comprising such a
substrate. The
present invention further relates to methods for producing dried green tobacco
material for an
aerosol-generating substrate.
In the production of combustible smoking articles, it is considered essential
to use only
tobacco material that has been sufficiently cured, since the use of uncured
green tobacco leaves
has been found to generate undesirable aromas and flavours upon burning of the
tobacco leaves
during smoking. By curing the tobacco material, through a process of drying
and browning, the
chemistry of the tobacco can be changed such that the undesirable aromas and
flavours are
minimised. Various methods of curing are used in the tobacco industry,
including but not limited
to flue curing, air curing and sun curing.
Aerosol-generating articles in which an aerosol-generating substrate, such as
a tobacco-
containing substrate, is heated rather than combusted, are known in the art.
Typically in such
articles, an aerosol is generated by the transfer of heat from a heat source
to a physically separate
aerosol-generating substrate or material, which may be located in contact
with, within, around, or
downstream of the heat source. During use of the aerosol-generating article,
volatile compounds
are released from the substrate by heat transfer from the heat source and are
entrained in air
drawn through the article. As the released compounds cool, they condense to
form an aerosol.
In the production of tobacco containing aerosol-generating substrates for such
heated
articles, cured tobacco material is used in order to produce an aerosol that
replicates the aromas
and flavours of the smoke from a combustible smoking article.
The tobacco curing process starts with the harvesting of the uncured green
tobacco
leaves, followed by a 'yellowing' phase lasting on average between 5 and 10
days, and finally a
drying phase, or browning phase, which may last for up to 50 days. As the
curing progresses,
the tobacco leaves change from their initial green colour, first to yellow and
finally to brown, as
the chlorophyll within the leaves degrades. In each phase, the curing is
continued until the desired
moisture level in the tobacco leaves is achieved. In the uncured green tobacco
leaves, the green
colour is a result of a high level of chlorophyll within the leaves. In
contrast, after curing, the
tobacco leaves are found to contain only a very low level of chlorophyll and
are brown in colour.
The curing processes that are used in the tobacco industry are relatively time
consuming
and often require the use of significant space and resources. Alternative,
faster processes for
drying the tobacco material without curing have been attempted. However, the
resultant dried
tobacco material has not been found to be suitable for use in combustible
smoking articles, since
the fast drying processes have not removed or sufficiently reduced the
constituents producing the
undesirable aromas and flavours upon burning of the tobacco.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-2-
It would be desirable to provide a novel aerosol-generating substrate for a
heated aerosol-
generating article that can be produced in a more efficient way but without
adversely affecting the
sensory properties of the resultant aerosol generated upon heating of the
substrate.
The present disclosure relates to an aerosol-generating substrate for an
aerosol-
generating article. The aerosol-generating substrate may comprise dried green
tobacco material,
an aerosol former and a binder.
The present disclosure also relates to an aerosol-generating article
comprising a rod of
such an aerosol-generating substrate.
The present disclosure also relates to the use of dried green tobacco leaves
in the
production of an aerosol-generating substrate for an aerosol-generating
article.
The present disclosure also relates to a dried green tobacco material having a
moisture
content of between about 4 percent by weight and about 15 percent by weight
and a chlorophyll
level of at least 0.5 milligrams per gram.
According to the present invention there is provided an aerosol-generating
substrate for a
heated aerosol-generating article, the aerosol-generating substrate comprising
dried green
tobacco material, an aerosol former and a binder. The aerosol-generating
substrate may be in
the form of a homogenised tobacco material comprising between 5 percent by
weight and 55
percent by weight of aerosol former.
According to the present invention there is further provided an aerosol-
generating article
comprising a rod of an aerosol-generating substrate, the aerosol-generating
substrate comprising
dried green tobacco material, an aerosol former and a binder. The aerosol-
generating substrate
may be in the form of a homogenised tobacco material comprising between 5
percent by weight
and 55 percent by weight of aerosol former.
According to the present invention there is further provided the use of dried
green tobacco
material in the production of an aerosol-generating substrate for an aerosol-
generating article, the
aerosol-generating substrate comprising dried green tobacco material, an
aerosol former and a
binder.
According to the present invention there is further provided a dried green
tobacco material
having a moisture content of between about 4 percent by weight and about 15
percent by weight
and a chlorophyll level of at least 0.5 milligrams per gram.
The present disclosure additionally relates to a method of producing dried
green tobacco
material for use in an aerosol-generating substrate as defined above. The
method may comprise:
providing uncured green tobacco leaves; drying the uncured green tobacco
leaves until a moisture
content of between 4 percent by weight and 15 percent by weight is achieved;
and cutting or
grinding the uncured green tobacco leaves to produce dried green tobacco
material. The
temperature, pressure and duration of the drying step may be selected such
that the dried green
tobacco material retains a chlorophyll level of at least 0.5 milligrams per
gram.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-3-
According to the present invention there is provided a method of producing
dried green
tobacco material for use in an aerosol-generating substrate according to the
present invention,
as defined above. The method comprises: providing uncured green tobacco
leaves; drying the
uncured green tobacco leaves until a moisture content of between 4 percent by
weight and 15
percent by weight is achieved; and cutting or grinding the uncured green
tobacco leaves to
produce dried green tobacco material. According to the invention, the
temperature, pressure and
duration of the drying step are preferably selected such that the dried green
tobacco material
retains a chlorophyll level of at least 0.5 milligrams per gram. Preferably,
the drying step is carried
out by heating the uncured green tobacco leaves to a temperature of between 75
degrees Celsius
and 120 degrees Celsius for no more than 4 hours.
According to the present invention there is further provided a dried green
tobacco material
produced by a method according to the invention, as defined above.
According to the present invention there is further provided a method for
producing
homogenised tobacco material for use in an aerosol-generating substrate
according to the
invention, as defined above. The method comprises the steps of: combining
dried green tobacco
material, an aerosol former, a binder and water to form a slurry; casting the
slurry on a surface to
form a sheet of homogenised tobacco material; and drying the sheet of
homogenised tobacco
material, wherein the sheet of homogenised tobacco material has an aerosol
former content of
between 5 percent by weight and 55 percent by weight, on a dry weight basis.
Any references below to the aerosol-generating substrates and aerosol-
generating articles
of the present invention should be considered to be applicable to all aspects
of the invention,
As used herein, the term "aerosol-generating article" refers to an article for
producing an
aerosol, wherein the article comprises an aerosol-generating substrate that is
suitable and
intended to be heated or combusted in order to release volatile compounds that
can form an
aerosol. A conventional cigarette is lit when a user applies a flame to one
end of the cigarette
and draws air through the other end. The localised heat provided by the flame
and the oxygen in
the air drawn through the cigarette causes the end of the cigarette to ignite,
and the resulting
combustion generates an inhalable smoke. By contrast, in "heated aerosol-
generating articles",
an aerosol is generated by heating an aerosol-generating substrate and not by
combusting the
aerosol-generating substrate. Known heated aerosol-generating articles
include, for example,
electrically heated aerosol-generating articles and aerosol-generating
articles in which an aerosol
is generated by the transfer of heat from a combustible fuel element or heat
source to a physically
separate aerosol-generating substrate.
Also known are aerosol-generating articles that are adapted to be used in an
aerosol-
generating system that supplies the aerosol former to the aerosol-generating
articles. In such a
system, the aerosol-generating substrate in the aerosol-generating articles
contain substantially
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-4-
less aerosol former relative to those aerosol-generating substrate which
carries and provides
substantially all the aerosol former used in forming the aerosol during
operation.
As used herein, the term "aerosol-generating substrate" refers to a substrate
capable of
producing upon heating volatile compounds, which can form an aerosol. The
aerosol generated
from aerosol-generating substrates may be visible to the human eye or
invisible and may include
vapours (for example, fine particles of substances, which are in a gaseous
state, that are ordinarily
liquid or solid at room temperature) as well as gases and liquid droplets of
condensed vapours.
The aerosol-generating substrate according to the present invention is
particularly suitable
for use in heated aerosol-generating articles, also known as heat-not-burn
articles.
The aerosol-generating substrate according to the present invention may take
any suitable
form that is capable of generating an aerosol upon heating. Preferably, the
aerosol-generating
substrate is in the form of a homogenised tobacco material, such as a cast
leaf, tobacco paper or
reconstituted tobacco material. Alternatively, the aerosol-generating
substrate may be in the form
of a loose tobacco material such as a tobacco cut filler.
As used herein, the term "homogenised tobacco material" encompasses any plant
material formed by the agglomeration of particles of tobacco plant. For
example, sheets or webs
of homogenised tobacco material for the aerosol-generating substrates of the
present invention
may be formed by agglomerating particles of plant material obtained by
pulverising, grinding or
comminuting tobacco plant material such as tobacco leaf lamina or tobacco leaf
stems. The
homogenised tobacco material may be produced by casting, extrusion, paper
making processes
or other any other suitable processes known in the art.
The term "dried green tobacco material" is used in the present specification
to refer to
material formed from tobacco leaves that have dried without being subjected to
any curing
process. The dried green tobacco material is therefore uncured. Such dried
green tobacco
material will typically retain its natural, green colour. The dried green
tobacco material is formed
from uncured green tobacco leaves that are dried as described below, in order
to provide a
desired moisture content, but without any curing. The dried green tobacco
material may be from
tobacco lamina, tobacco stems, or a combination thereof. The dried green
tobacco material
preferably has a moisture content of less than 15 percent by weight.
The term "uncured green tobacco leaves" is used in the present specification
to refer to
tobacco leaves that have not been subjected to any curing process after
harvesting.
The present invention therefore provides a novel aerosol-generating substrate
which is
formed from at least a proportion of dried green tobacco material, which will
typically be provided
in combination with a proportion of cured tobacco material.
The inventors have surprisingly found that an aerosol-generating substrate for
a heated
aerosol-generating article can be formed using at least a proportion of dried
green tobacco
material in place of cured tobacco material, without adversely impacting the
sensory properties
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-5-
of the resultant aerosol. In particular, it has been surprisingly found that
when a substrate
comprising dried green tobacco material is heated, rather combusted, to form
an aerosol, the
resultant aerosol does not have the unpleasant aromas or flavours that are
generated when green
tobacco material is used in a combustible smoking article, as described above.
The dried green tobacco material can advantageously be produced significantly
more
quickly and more efficiently than cured tobacco material, since it is possible
to use a fast drying
process to achieve the desired moisture content rather than a much slower
curing process. The
dried green tobacco material can also be produced naturally and organically,
thereby providing a
more sustainable process for generating aerosol-generating substrates.
Advantageously, the methods of drying uncured green tobacco leaves to produce
a dried
green tobacco material suitable for use in aerosol-generating substrate of the
present invention
can be applied to all tobacco types.
Furthermore, it has been found that the uncured green tobacco leaves can be
dried and
processed without destemming, which further improves the efficiency of
production of the aerosol-
generating substrate according to the invention.
The curing process of tobacco is known to affect the chemical composition of
the tobacco
and in particular, the levels of certain tobacco constituents which affect the
flavour of the resultant
aerosol generated from the aerosol-generating substrate and the levels of
certain undesirable
tobacco constituents. For example, it has been surprisingly found that as a
result of the absence
of a curing step in the production of dried green tobacco material,
significantly reduced levels of
asparagine, ammonia, free amino acids and total alkaloids are present than in
a cured tobacco.
This has an effect on the aerosol produced from an aerosol-generating
substrate according to the
invention, which will include less undesirable compounds such as acrylamide,
hydrogen sulphide
(H2S) and methanethiol (MeSH). The inclusion of the dried green tobacco
material in the aerosol-
generating substrate therefore enables an improved aerosol to be generated
upon heating of the
substrate than is generated from a substrate with only cured tobacco and no
dried green tobacco
material.
The dried green tobacco material has also been found to have a significantly
higher level
of sugars than cured tobacco material. The presence of the sugars within the
dried green tobacco
material can advantageously facilitate the manufacture of the aerosol-
generating substrate, for
example, where the aerosol-generating substrate is formed using a cast leaf
process, as
described below. In particular, the relatively high level of sugar within the
dried green tobacco
material improves the flexibility of a sheet of aerosol-generating substrate
formed from the dried
green tobacco material.
As described above, when a tobacco material is not subjected to a curing
process, it
typically retains its natural, high level of chlorophyll and therefore its
green colour. As a direct
result of the inclusion of a proportion of dried green tobacco material in the
aerosol-generating
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-6-
substrate of the present invention, the level of chlorophyll in the substrate
is significantly higher
than would be measured in a typical substrate formed from only cured tobacco.
A cured tobacco
is always brown in colour and has a low, often negligible amount of remaining
chlorophyll, due to
the degradation of the chlorophyll during curing.
Preferably, the homogenised tobacco material comprises at least 0.1 milligrams
of
chlorophyll per gram, on a dry weight basis. The presence of chlorophyll
within the substrate at a
level that is higher than 0.1 milligrams per gram of homogenised tobacco
material, on a dry weight
basis, is a clear indicator that dried green tobacco material has been
incorporated.
Preferably, the homogenised tobacco material comprises at least about 0.2
milligrams of
chlorophyll per gram, more preferably at least about 0.5 milligrams of
chlorophyll per gram, more
preferably at least about 1.0 milligrams of chlorophyll per gram, more
preferably at least about
1.5 milligrams of chlorophyll per gram, more preferably at least about 2.0
milligrams of chlorophyll
per gram, more preferably at least about 2.5 milligrams of chlorophyll per
gram , more preferably
at least about 3.0 milligrams of chlorophyll per gram, on a dry weight basis.
The higher the level of dried green tobacco material used in the homogenised
tobacco
material, the higher the level of chlorophyll that will be present in the
aerosol-generating substrate.
However, even with a relatively low proportion of dried green tobacco material
forming the
aerosol-generating substrate, the level of chlorophyll in the substrate will
be considerably higher
than would be present in a substrate formed from only cured tobacco material
and without any
dried green tobacco material.
The maximum level of chlorophyll within the aerosol-generating substrate will
depend
upon the type and amount of the dried green tobacco material within the
aerosol-generating
substrate. Typically, the homogenised tobacco material will comprise less than
about 10.0
milligrams of chlorophyll per gram, or below about 8.0 milligrams of
chlorophyll per gram, on a
dry weight basis.
The dried green tobacco material used in the aerosol-generating substrate
according to
the invention preferably has a chlorophyll level of at least about 0.5
milligrams of chlorophyll per
gram, more preferably at least about 1.0 milligrams of chlorophyll per gram,
on a dry weight basis.
A preferred method for measuring the chlorophyll content of a sample of a
homogenised
tobacco material containing dried green tobacco material, or a sample of dried
green tobacco
material, may be found in "Lichtenthaler, HK and AR We//burn (1983)
Determinations of total
carotenoids and chlorophylls a and b of leaf extracts in different solvents;
Biochemical Society
Transactions 11 :591-592".
In this method, an aqueous 80 percent acetone extract is produced from a
sample of the
homogenised tobacco material and the absorbance of the extract at specific
wavelengths is
measured using a spectrophotometer. The level of chlorophyll a and chlorophyll
b can then be
calculated using equations set out below:
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-7-
Chlorophyll a (pg/ml) = 12.21 (A663) - 2.81 (A646)
Chlorophyll b (pg/ml) = 20.13 (A646)¨ 5.03 (A663)
wherein A663 is the measured absorbance at 663 nm and A646 is the measured
absorbance
at 646 nm. The values of chlorophyll defined above in relation to the
homogenised tobacco
material of the present invention correspond to the total chlorophyll content,
which is the sum of
the content of chlorophyll a and chlorophyll b.
An alternative method for measuring the chlorophyll content of a sample of a
homogenised
tobacco material containing dried green tobacco material, or a sample of dried
green tobacco
material, may be found in in "Porra, RJ (2002) The chequered history of the
development and
use of simultaneous equations for the accurate determination of chlorophylls a
and b;
Photosynthesis Research 73: 149 ¨ 156", which uses the alternative equations:
Chlorophyll a (pg/m1) = 12.25 (A663.6) - 2.55 (A646.6)
Chlorophyll b (pg/ml) = 20.31 (A646.6) - 4.91 (A663.6)
wherein A663.6 is the measured absorbance at 663.6 nm and A6466 is the
measured
absorbance at 646.6 nm.
All of the other components of the dried green tobacco material that are
referred to below
may be measured by suitable GC-MS or LC-MS techniques, which would be well
known to the
skilled person.
The inclusion of dried green tobacco material in the aerosol-generating
substrate of the
present invention has been found to advantageously provide a decrease in the
level of asparagine
in the aerosol-generating substrate compared to an equivalent aerosol-
generating substrate
formed of cured tobacco material only.
Preferably, the homogenised tobacco material comprises no more than about 2.5
milligrams of asparagine per gram, more preferably no more than about 2.0
milligrams of
asparagine per gram, more preferably no more than about 1.5 milligrams of
asparagine per gram,
more preferably no more than about 0.75 milligrams of asparagine per gram and
most preferably
no more than about 0.3 milligrams of asparagine per gram, on a dry weight
basis.
The aerosol-generating substrate according to the invention will typically
comprise a lower
level of asparagine than an aerosol-generating substrate formed from cured
tobacco material
alone, since the level of asparagine in the tobacco leaf has been found to
increase significantly
during the curing process. For example, for certain tobacco types, the level
of asparagine in the
tobacco leaf has been found to be more than 20 times higher after curing of
the tobacco leaf than
for the uncured green tobacco leaf.
Preferably, the dried green tobacco material has not been genetically modified
and in
particular, it has not been genetically modified to reduce the asparagine
content.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-8-
Preferably, the dried green tobacco material is substantially free from added
asparaginase. The asparaginase that is present in the dried green tobacco
material is therefore
only that which is naturally present.
The level of asparagine in tobacco leaf varies depending upon the tobacco
type. In certain
preferred embodiments, the aerosol-generating substrate comprises dried green
tobacco material
which are derived from Burley tobacco. The dried green Burley tobacco material
preferably
comprise no more than about 0.5 milligrams of asparagine per gram, on a dry
weight basis.
The asparagine content of a homogenised tobacco material can be measured using
known spectroscopic techniques. A preferred method for determining asparagine
content is
described in MP 1471 rev 5 (2011) of Chelab Silliker S.r.l. Merieux
Nutrisciences Company.
Another suitable method is described in UNI EN ISO 13903:2005. A further
suitable method is
described in "Evaluation of the Content of Free Amino Acids in Tobacco by a
New Liquid
Chromatography-Tandem Mass Spectrometry Technique; S. C. Moldoveanu et a!'
(DOI:
10.1515/cttr-2015-0023).
The resultant aerosol generated from the aerosol-generating substrate
according to the
invention therefore advantageously has a significantly lower level of
acrylamide, which is
generated from the asparagine during heating of the aerosol-generating
substrate.
Preferably, upon heating of the aerosol-generating substrate according to the
invention
under conditions according to Test Method A, an aerosol is generated
comprising no more than
about 4 micrograms of acrylamide per gram of substrate, preferably no more
than about 3
micrograms of acrylamide per gram of substrate.
For preferred embodiments of the invention in which the aerosol-generating
substrate
comprises dried green tobacco material from Burley tobacco, the level of
acrylamide in the aerosol
generated from the substrate when the substrate is heated according to Test
Method A is
preferably no more than about 4 micrograms of acrylamide per gram of
substrate, preferably no
more than about 3 micrograms of acrylamide per gram of substrate.
For the purposes of the invention, the aerosol-generating substrate is heated
according to
"Test Method A". In Test Method A, an aerosol-generating article incorporating
the aerosol-
generating substrate is heated in a Tobacco Heating System 2.2 holder (THS2.2
holder) under
the Health Canada machine-smoking regimen. For the purposes of carrying out
Test Method A,
the aerosol-generating substrate is provided in an aerosol-generating article
that is compatible
with the THS2.2 holder.
The Tobacco Heating System 2.2 holder (THS2.2 holder) corresponds to the
commercially
available IQOS device (Philip Morris Products SA, Switzerland) as described in
Smith et al., 2016,
Regul. Toxicol. Pharmacol. 81 (S2) S82-592. Aerosol-generating articles for
use in conjunction
with the IQOS device are also commercially available.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-9-
The Health Canada smoking regimen is a well-defined and accepted smoking
protocol as
defined in Health Canada 2000 ¨ Tobacco Products Information Regulations
SOR/2000-273,
Schedule 2; published by Ministry of Justice Canada. The test method is
described in ISO/TR
19478-1:2014. In a Health Canada smoking test, an aerosol is collected from
the sample aerosol-
generating substrate over 12 puffs with a puff volume of 55 millimetres, puff
duration of 2 seconds
and puff interval of 30 seconds, with all ventilation blocked if ventilation
is present.
Thus, in the context of the present invention, the expression "upon heating of
the aerosol-
generating substrate according to Test Method A" means upon heating of the
aerosol-generating
substrate in a THS2.2 holder under the Health Canada machine-smoking regimen
as defined in
Health Canada 2000 ¨ Tobacco Products Information Regulations SOR/2000-273,
Schedule 2;
published by Ministry of Justice Canada, the test method being described in
ISO/TR 19478-
1:2014.
For the purposes of analysis, the aerosol generated from the heating of the
aerosol-
generating substrate is trapped using suitable apparatus, depending upon the
method of analysis
that is to be used. The aerosol may then be analysed using known spectroscopy
techniques,
such as liquid chromatography or gas chromatography techniques, that would be
known to the
skilled person.
The inclusion of dried green tobacco material in the aerosol-generating
substrate of the
present invention has further been found to advantageously provide a decrease
in the level of
ammonia in the aerosol-generating substrate compared to an equivalent aerosol-
generating
substrate formed of cured tobacco material only.
Preferably, the homogenised tobacco material comprises no more than about 0.5
milligrams of ammonia per gram, more preferably no more than about 0.2
milligrams of ammonia
per gram and most preferably no more than about 0.1 milligrams of ammonia per
gram, on a dry
weight basis. The aerosol-generating substrate according to the invention will
typically comprise
a lower level of ammonia than an aerosol-generating substrate formed from
cured tobacco
material alone, since the level of ammonia in the tobacco leaf has been found
to increase
significantly during the curing process. For example, for certain tobacco
types, the level of
ammonia in the tobacco leaf has been found to be more than 20 times higher
after curing of the
tobacco leaf than for the uncured green tobacco leaf.
The level of ammonia in a homogenised tobacco material can be measured
according to
the Coresta Recommended Method No. 79 "Determination of Ammonia in Tobacco and
Tobacco
Products by Ion Chromatographic Analysis" (March 2018).
The level of ammonia in tobacco leaf varies depending upon the tobacco type.
In certain
preferred embodiments, the aerosol-generating substrate comprises dried green
tobacco material
which is derived from Burley tobacco. The dried green Burley tobacco material
preferably
comprises no more than about 0.2 milligrams of ammonia per gram, on a dry
weight basis.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-10-
The resultant aerosol generated from the aerosol-generating substrate
according to the
invention therefore advantageously has a significantly lower level of ammonia,
which is volatilised
from the aerosol-generating substrate during heating.
Preferably, upon heating of the aerosol-generating substrate according to the
invention
under conditions according to Test Method A, an aerosol is generated
comprising no more than
about 40 micrograms of ammonia per gram of substrate, preferably no more than
about 30
micrograms of ammonia per gram of substrate.
For preferred embodiments of the invention in which the aerosol-generating
substrate
comprises dried green tobacco material from Burley tobacco, the level of
ammonia in the aerosol
generated from the substrate when the substrate is heated according to Test
Method A is
preferably no more than about 40 micrograms of acrylamide per gram of
substrate, preferably no
more than about 30 micrograms of ammonia per gram of substrate.
The inclusion of dried green tobacco material in the aerosol-generating
substrate of the
present invention has further been found to advantageously provide a decrease
in the level of
total free amino acids in the aerosol-generating substrate compared to an
equivalent aerosol-
generating substrate formed of cured tobacco material only.
Preferably, the homogenised tobacco material comprises no more than about 12
milligrams of total free amino acids per gram, more preferably no more than
about 8 milligrams
of total free amino acids per gram and most preferably no more than about 6
milligrams of total
free amino acids per gram, on a dry weight basis. The aerosol-generating
substrate according to
the invention will typically comprise a lower level of total free amino acids
than an aerosol-
generating substrate formed from cured tobacco material alone, since the level
of total free amino
acids in the tobacco leaf has been found to increase significantly during the
curing process. For
example, for certain tobacco types, the level of total free amino acids in the
tobacco leaf has been
found to be more than 5 times higher after curing of the tobacco leaf than for
the uncured green
tobacco leaf.
The level of total free amino acids in tobacco leaf varies depending upon the
tobacco type.
In certain preferred embodiments, the aerosol-generating substrate comprises
dried green
tobacco material which are derived from Burley tobacco. The dried green Burley
tobacco material
preferably comprises no more than about 20 milligrams of total free amino
acids per gram, on a
dry weight basis.
The resultant aerosol generated from the aerosol-generating substrate
according to the
invention therefore advantageously has a significantly lower level of hydrogen
sulphide and
methanethiol, which are generated from the free amino acids in the aerosol-
generating substrate
during heating.
Preferably, upon heating of the aerosol-generating substrate according to the
invention
under conditions according to Test Method A, an aerosol is generated
comprising no more than
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
- 11 -
about 6 micrograms of hydrogen sulphide per gram of substrate, preferably no
more than about
micrograms of hydrogen sulphide per gram of substrate.
For preferred embodiments of the invention in which the aerosol-generating
substrate
comprises dried green tobacco material from Burley tobacco, the level of
hydrogen sulphide in
5
the aerosol generated from the substrate when the substrate is heated
according to Test Method
A is preferably no more than about 6 micrograms of hydrogen sulphide per gram
of substrate,
preferably no more than about 5 micrograms of hydrogen sulphide per gram of
substrate.
Preferably, upon heating of the aerosol-generating substrate according to the
invention
under conditions according to Test Method A, an aerosol is generated
comprising no more than
about 10 micrograms of methanethiol per gram of substrate, preferably no more
than about 9
micrograms of methanethiol per gram of substrate.
For preferred embodiments of the invention in which the aerosol-generating
substrate
comprises dried green tobacco material from Burley tobacco, the level of
methanethiol in the
aerosol generated from the substrate when the substrate is heated according to
Test Method A
is preferably no more than about 10 micrograms of methanethiol per gram of
substrate, preferably
no more than about 9 micrograms of methanethiol per gram of substrate.
A reduction in the level of hydrogen sulphide and methanediol in the aerosol
generated
from aerosol-generating substrate of the present invention is advantageous,
since these
compounds are known to be responsible for undesirable sulphurous odours during
heating.
The inclusion of dried green tobacco material in the aerosol-generating
substrate of the
present invention has further been found to advantageously provide a decrease
in the level of
certain TSNAs (tobacco specific nitrosamines) in the aerosol-generating
substrate compared to
an equivalent aerosol-generating substrate formed of cured tobacco material
only.
For example, the aerosol-generating substrate according to the invention will
typically
comprise a lower level of NNN (N-Nitrosonornicotine) than an aerosol-
generating substrate
formed from cured tobacco material alone, since the level of NNN and other
TSNAs in the tobacco
leaf has been found to increase significantly during the curing process. For
certain tobacco types,
the level of NNN in the tobacco leaf has been found to be more than 5 times
higher after curing
of the tobacco leaf than for the uncured green tobacco leaf.
The level of NNN in tobacco leaf varies depending upon the tobacco type. In
certain
preferred embodiments, the aerosol-generating substrate comprises dried green
tobacco material
which is derived from Burley tobacco. The dried green Burley tobacco material
preferably
comprise no more than about 500 nanograms of NNN per gram, on a dry weight
basis.
The resultant aerosol generated from the aerosol-generating substrate
according to the
invention therefore advantageously has a significantly lower level of NNN,
which is volatilised
from the aerosol-generating substrate during heating.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-12-
The inclusion of dried green tobacco material in the aerosol-generating
substrate of the
present invention has been found to provide a significant increase in the
level of
phosphatidylethanolamine (PE) in the aerosol-generating substrate compared to
an equivalent
aerosol-generating substrate formed of cured tobacco material only. PE is an
extra-chloroplastic
lipid found in plant membranes. The presence of PE above a certain threshold
level is clearly
indicative of the inclusion of dried green tobacco material within an aerosol-
generating substrate.
The level of some of the PE molecular species, including PE 36:6, PE 34:3, PE
36:5 and PE 34:2,
has been found to be at least 8 times higher, in some cases at least 10 times
higher, in the dried
green tobacco material than in cured tobacco material of the same tobacco
type.
The term "PE 36:6" refers to a PE molecular species having 36 carbons in the
two acyl
chains and 6 double bonds in total. The same terminology applies to the other
molecular species
listed above.
Preferably, the aerosol produced from an aerosol-generating substrate
according to the
present invention during Test Method A further comprises at least about 0.1
micrograms of
nicotine per gram of the substrate, more preferably at least about 1 microgram
of nicotine per
gram of the substrate, more preferably at least about 2 micrograms of nicotine
per gram of the
substrate. Preferably, the aerosol comprises up to about 10 micrograms of
nicotine per gram of
the substrate, more preferably up to about 7.5 micrograms of nicotine per gram
of the substrate,
more preferably up to about 4 micrograms of nicotine per gram of the
substrate. For example,
the aerosol may comprise between about 0.1 micrograms and about 10 micrograms
of nicotine
per gram of the substrate, or between about 1 microgram and about 7.5
micrograms of nicotine
per gram of the substrate, or between about 2 micrograms and about 4
micrograms of nicotine
per gram of the substrate. In some embodiments of the present invention, the
aerosol may
contain zero micrograms of nicotine.
Various methods known in the art can be applied to measure the amount of
nicotine in the
aerosol.
The aerosol produced from an aerosol-generating substrate according to the
invention
during Test Method A may further comprise at least about 5 milligrams of
aerosol former per gram
of aerosol-generating substrate, or at least about 10 milligrams of aerosol
per gram of the
substrate or at least about 15 milligrams of aerosol former per gram of the
substrate. Alternatively
or in addition, the aerosol may comprises up to about 30 milligrams of aerosol
former per gram
of the substrate, or up to about 25 milligrams aerosol former per gram of the
substrate, or up to
about 20 milligrams aerosol former per gram of the substrate. For example, the
aerosol may
comprise between about 5 milligrams and about 30 milligrams of aerosol former
per gram of the
substrate, or between about 10 milligrams and about 25 milligrams of aerosol
former per gram of
the substrate, or between about 15 milligrams and about 20 milligrams of
aerosol former per gram
of the substrate. In alternative embodiments, the aerosol may comprise less
than 5 milligrams of
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-13-
aerosol former per gram of substrate. This may be appropriate, for example, if
an aerosol former
is provided separately within the aerosol-generating article or aerosol-
generating device.
Suitable aerosol formers for use in the present invention are set out below.
Various methods known in the art can be applied to measure the amount of
aerosol former
in the aerosol.
Preferably, the homogenised tobacco material of aerosol-generating substrates
according
to the invention comprises at least about 1 percent by weight of dried green
tobacco material, on
a dry weight basis. Preferably, the homogenised tobacco material comprises at
least about 2
percent by weight of dried green tobacco material, more preferably at least
about 4 percent by
weight of dried green tobacco material, more preferably at least about 6
percent by weight of dried
green tobacco material, more preferably at least about 8 percent by weight of
dried green tobacco
material, more preferably at least about 10 percent by weight of dried green
tobacco material, on
a dry weight basis.
The homogenised tobacco material may comprise up to about 75 percent by weight
of dried
green tobacco material, on a dry weight basis. Preferably, the homogenised
tobacco material
comprises up to about 70 percent by weight of dried green tobacco material,
more preferably up
to about 65 percent by weight of dried green tobacco material, more preferably
up to about 60
percent by weight of dried green tobacco material, more preferably up to about
55 percent by
weight of dried green tobacco material, more preferably up to about 50 percent
by weight of dried
green tobacco material, on a dry weight basis.
For example, the homogenised tobacco material may comprise between about 1
percent
and about 75 percent by weight of dried green tobacco material, or about 2
percent and about 70
percent by weight of dried green tobacco material, or between about 4 percent
and about 65
percent by weight of dried green tobacco material, or between about 6 percent
and about 60
percent by weight of dried green tobacco material, or between about 8 percent
and about 55
percent by weight of dried green tobacco material, or between about 10 percent
and about 50
percent by weight of dried green tobacco material, on a dry weight basis.
In certain particularly preferred embodiments of the invention, the
homogenised tobacco
material comprises between about 10 percent by weight and about 30 percent by
weight of dried
green tobacco material, on a dry weight basis.
In certain embodiments of the invention, the aerosol-generating plant material
forming the
homogenised tobacco material may include at least 98 percent by weight of
dried green tobacco
material or at least 95 percent by weight of dried green tobacco material or
at least 90 percent by
weight of dried green tobacco material, based on dry weight of the plant
material. In such
embodiments, the aerosol-generating substrate therefore comprises dried green
tobacco
material, with substantially no cured tobacco material. For example, the plant
material forming
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-14-
the homogenised tobacco material may comprise about 100 percent by weight of
dried green
tobacco material.
In alternative embodiments of the invention, the homogenised tobacco material
may
comprise dried green tobacco material in combination with cured tobacco
material, as described
below.
Alternatively or in addition to cured tobacco material, the homogenised
tobacco material
may comprise aerosol-generating plant material derived from one or more plants
including but
not limited to cannabis, tea, ginger, eucalyptus, clove, peppermint, star
anise, rosemary,
chamomile, thyme and dill seed.
In the following description of the invention, the term "plant material" is
used to refer
collectively to the aerosol-generating plant material that is used to form the
aerosol-generating
substrate. The plant material may consist substantially of dried green tobacco
material or may
be a mixture of dried green tobacco material with cured tobacco material or
other aerosol-
generating plant material as defined above. Preferably, the plant material is
in the form of plant
particles which may consist substantially of dried green tobacco particles or
may be a mixture of
dried green tobacco particles with cured tobacco particles. The term "plant
material" does not
include any inert plant material incorporated into the aerosol-generating
substrate and which does
not contribute to the aerosol generated upon heating of the aerosol-generating
substrate.
Preferably, the homogenised tobacco material according to the invention
further comprises
at least about 1 percent by weight of cured tobacco material. For example, the
homogenised
tobacco material may comprise at least about 2 percent by weight of cured
tobacco material, or
at least about 4 percent by weight of cured tobacco material, or at least
about 6 percent by weight
of cured tobacco material, or at least about 8 percent by weight of cured
tobacco material, or at
least about 10 percent by weight of cured tobacco material, on a dry weight
basis.
The homogenised tobacco material may comprise up to about 75 percent by weight
of cured
tobacco material, or up to about 70 percent by weight of cured tobacco
material, or at least about
65 percent by weight of cured tobacco material, or at least 60 percent by
weight of cured tobacco
material, or at least about 55 percent by weight of cured tobacco material, or
at least about 50
percent by weight of cured tobacco material, on a dry weight basis.
The cured tobacco material is preferably in the form of cured tobacco
particles.
The term "cured tobacco material" is used in the present specification to
refer to material
derived from tobacco plants that has been subjected to a known curing process
for at least 5
days. Cured tobacco material, such as cured tobacco leaves, will typically be
brown in colour and
have a chlorophyll level of no more than 0.25 milligrams per gram, on a dry
weight basis.
The ratio of dried green tobacco material to cured tobacco material in the
homogenised
tobacco material may be varied depending on the desired content of the dried
green tobacco
material in the homogenised tobacco material. Preferably, the ratio of dried
green tobacco
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-15-
material to cured tobacco material in the homogenised tobacco material is no
more than 1 to 1
(1:1). In such embodiments, the weight amount of cured tobacco material in the
homogenised
tobacco material is equal to or greater than the weight amount of dried green
tobacco material in
the homogenised tobacco material, on a dry weight basis.
With reference to the present invention, the term "tobacco material", whether
referring to
the dried green tobacco material or cured tobacco material, may be material of
any plant member
of the genus Nicotiana. The term "tobacco particles" encompasses ground or
powdered tobacco
leaf lamina, ground or powdered tobacco leaf stems, tobacco dust, tobacco
fines, and other
particulate tobacco by-products formed during the treating, handling and
shipping of tobacco. In
a preferred embodiment, the tobacco material is substantially all derived from
tobacco leaf lamina.
By contrast, isolated nicotine and nicotine salts are compounds derived from
tobacco but are not
considered tobacco material for purposes of the invention and are not included
in the percentage
of plant material.
The tobacco material may be prepared from one or more varieties of tobacco
plants. Any
type of tobacco may be used in a blend. Examples of tobacco types that may be
used for the
dried green tobacco material include, but are not limited to, Burley tobacco,
Maryland tobacco,
Oriental tobacco, Virginia tobacco, and other speciality tobaccos. Examples of
tobacco types that
may be used for the cured tobacco types include, but are not limited to, sun-
cured tobacco, flue-
cured tobacco, Burley tobacco, Maryland tobacco, Oriental tobacco, Virginia
tobacco, and other
speciality tobaccos.
Burley tobacco plays a significant role in many tobacco blends. Burley tobacco
has a
distinctive flavour and aroma and also has an ability to absorb large amounts
of casing.
Oriental is a type of tobacco which has small leaves, and high aromatic
qualities. However,
Oriental tobacco has a milder flavour than, for example, Burley. Generally,
therefore, Oriental
tobacco is used in relatively small proportions in tobacco blends.
Flue-curing is a method of curing tobacco, which is particularly used with
Virginia tobaccos.
During the flue-curing process, heated air is circulated through densely
packed tobacco. During
a first stage, the tobacco leaves turn yellow and wilt. During a second stage,
the laminae of the
leaves are completely dried. During a third stage, the leaf stems are
completely dried.
Kasturi, Madura and Jatim are subtypes of sun-cured tobacco that can be used.
The dried green tobacco material or the cured tobacco material may comprise a
blend of
different tobacco types.
The tobacco material may have a nicotine content of at least about 2.5 percent
by weight,
based on dry weight. More preferably, the tobacco material may have a nicotine
content of at
least about 3 percent, even more preferably at least about 3.2 percent, even
more preferably at
least about 3.5 percent, most preferably at least about 4 percent by weight,
based on dry weight.
The curing process does not appear to affect the nicotine level of tobacco
leaf to a significant
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-16-
extent and therefore these values apply to both the dried green tobacco
material and the cured
tobacco material, where present.
Nicotine may optionally be incorporated into the aerosol-generating substrate
although this
would be considered as a non-tobacco material for the purposes of the
invention. The nicotine
may comprise one or more nicotine salts selected from the list consisting of
nicotine lactate,
nicotine citrate, nicotine pyruvate, nicotine bitartrate, nicotine benzoate,
nicotine pectate, nicotine
alginate, and nicotine salicylate. Nicotine may be incorporated in addition to
a tobacco with low
nicotine content, or nicotine may be incorporated into an aerosol-generating
substrate that has a
reduced or zero tobacco content.
Preferably, the homogenised tobacco material comprises at least about 0.1 mg
of nicotine
per gram of the substrate, on a dry weight basis. More preferably, the
homogenised tobacco
material comprise at least about 0.5 mg of nicotine per gram of the substrate,
more preferably at
least about 1 mg of nicotine per gram of the substrate, more preferably at
least about 1.5 mg of
nicotine per gram of the substrate, more preferably at least about 2 mg of
nicotine per gram of
the substrate, more preferably at least about 3 mg of nicotine per gram of the
substrate, more
preferably at least about 4 mg of nicotine per gram of the substrate, more
preferably at least about
5 mg of nicotine per gram of the substrate, on a dry weight basis.
Preferably, the homogenised tobacco material comprises up to about 50 mg of
nicotine per
gram of the substrate, on a dry weight basis. More preferably, the homogenised
tobacco material
comprises up to about 45 mg of nicotine per gram of the substrate, more
preferably up to about
40 mg of nicotine per gram of the substrate, more preferably up to about 35 mg
of nicotine per
gram of the substrate, more preferably up to about 30 mg of nicotine per gram
of the substrate,
more preferably up to about 25 mg of nicotine per gram of the substrate, more
preferably up to
about 20 mg of nicotine per gram of the substrate, on a dry weight basis.
For example, the homogenised tobacco material may comprise between about 0.1
mg and
about 50 mg of nicotine per gram of the substrate, or between about 0.5 mg and
about 45 mg of
nicotine per gram of the substrate, or between about 1 mg and about 40 mg of
nicotine per gram
of the substrate, or between about 2 mg and about 35 mg of nicotine per gram
of the substrate,
or between about 5 mg and about 30 mg of nicotine per gram of the substrate,
or between about
10 mg and about 25 mg of nicotine per gram of the substrate, or between about
15 mg and about
20 mg of nicotine per gram of the substrate, on a dry weight basis. In certain
preferred
embodiments of the invention, the homogenised tobacco material comprises
between about 1 mg
and about 20 mg of nicotine per gram of the substrate, on a dry weight basis.
The defined ranges of nicotine content for the homogenised tobacco material
include all
forms of nicotine which may be present in the homogenised tobacco material,
including nicotine
intrinsically present in tobacco material as well as nicotine that has
optionally been added
separately to the homogenised tobacco material, for example, in the form of a
nicotine salt.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-17-
The nicotine content of a homogenised tobacco material can be measured
according to
the hexane method described in Coresta Recommended Method No. 62
"Determination of
Nicotine in Tobacco and Tobacco Products by Gas Chromatographic Analysis"
(April 2020).
The homogenised tobacco material preferably comprises at least about 55
percent by
weight of the plant material including dried green tobacco material, as
described above, more
preferably at least about 60 percent by weight of the plant material and more
preferably at least
about 65 percent by weight of the plant material, on a dry weight basis. The
homogenised tobacco
material preferably comprises no more than about 95 percent by weight of the
plant material,
more preferably no more than about 90 percent by weight of the plant material
and more
preferably no more than about 85 percent by weight of the plant material, on a
dry weight basis.
For example, the homogenised tobacco material may comprise between about 55
percent and
about 95 percent by weight of the plant material, or between about 60 percent
and about 90
percent by weight of the plant material, or between about 65 percent and about
85 percent by
weight of the plant material, on a dry weight basis. In one particularly
preferred embodiment, the
homogenised tobacco material comprises about 75 percent by weight of the plant
material, on a
dry weight basis.
In certain preferred embodiments, the total weight amount plant material is no
more than
about 75 percent by weight on a dry weight basis.
The plant material is therefore combined with one or more other components to
form the
homogenised tobacco material.
As defined above, the homogenised tobacco material further comprises an
aerosol former.
Upon volatilisation, an aerosol former can convey other vaporised compounds
released from the
homogenised tobacco material upon heating, such as nicotine and flavourants,
in an aerosol.
The aerosolisation of a specific compound from an homogenised tobacco material
is determined
not solely by its boiling point. The quantity of a compound that is
aerosolised can be affected by
the physical form of the substrate, as well as by the other components that
are also present in the
substrate. The stability of a compound under the temperature and time frame of
aerosolisation
will also affect the amount of the compound that is present in an aerosol.
Suitable aerosol formers for inclusion in the homogenised tobacco material are
known in
the art and include, but are not limited to: polyhydric alcohols, such as
triethylene glycol, propylene
glycol, 1,3-butanediol and glycerol; esters of polyhydric alcohols, such as
glycerol mono-, di- or
triacetate; and aliphatic esters of mono-, di- or polycarboxylic acids, such
as dimethyl
dodecanedioate and dimethyl tetradecanedioate. The homogenised tobacco
material may
comprise a single aerosol former, or a combination of two or more aerosol
formers.
If the substrate is intended for use in an aerosol-generating article for an
electrically-
operated aerosol-generating system having a heating element, the aerosol
former is preferably
glycerol.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-18-
The amount of aerosol former may be adapted depending on the composition of
the
homogenised tobacco material, such as the type or amount of the plant
material, in order to
achieve an aerosol having the desired levels of flavour compounds from the
plant material. The
amount of aerosol former may also be adapted depending on the way in which it
is intended to
heat the aerosol-generating substrate during use and in particular, the
temperature to which the
homogenised tobacco material will be heated during heating of the aerosol-
generating article in
an associated aerosol-generating device.
The homogenised tobacco material preferably has an aerosol former content of
between
about 5 percent and about 55 percent by weight on a dry weight basis, such as
between about
10 percent and about 45 percent by weight on a dry weight basis, or between
about 15 percent
and about 40 percent by weight on a dry weight basis.
The aerosol former content may be between about 5 percent and about 30 percent
by
weight, on a dry weight basis. For example, in homogenised tobacco materials
according to
certain preferred embodiments of the invention, the aerosol former content is
preferably between
about 5 percent and about 30 percent by weight, more preferably between about
10 percent and
about 25 percent by weight, more preferably between about 15 percent and about
20 percent by
weight on a dry weight basis.
Alternatively, the aerosol former content may be between about 15 percent and
about 55
percent by weight, on a dry weight basis. For example, in homogenised tobacco
materials
according to alternative preferred embodiments of the invention, the aerosol
former content is
preferably between about 15 percent and about 55 percent by weight, more
preferably between
about 25 percent and about 50 percent by weight, more preferably between about
35 percent and
about 45 percent by weight on a dry weight basis.
In other embodiments, the homogenised tobacco material may have an aerosol
former
content of about 1 percent to about 5 percent by weight on a dry weight basis.
For example, if
the substrate is intended for use in an aerosol-generating article in which
aerosol former is kept
in a reservoir separate from the substrate, the substrate may have an aerosol
former content of
greater than 1 percent and less than about 5 percent. In such embodiments, the
aerosol former
is volatilised upon heating and a stream of the aerosol former is contacted
with the homogenised
tobacco material so as to entrain the flavours from the homogenised tobacco
material in the
aerosol.
The aerosol former may act as a humectant in the homogenised tobacco material.
As defined above, the homogenised tobacco material further comprises a binder
to alter the
mechanical properties of the plant material, wherein the binder is included in
the homogenised
tobacco material during manufacturing as described herein. Suitable exogenous
binders would
be known to the skilled person and include but are not limited to: gums such
as, for example, guar
gum, xanthan gum, arabic gum and locust bean gum; cellulosic binders, for
example, cellulose
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-19-
ethers such as hydroxypropyl cellulose, carboxymethyl cellulose (CMC),
hydroxyethyl cellulose,
methyl cellulose and ethyl cellulose; polysaccharides such as, for example,
starches, organic
acids, such as alginic acid, conjugate base salts of organic acids, such as
sodium-alginate, agar
and pectins; and combinations thereof. Preferably, the binder comprises guar
gum.
Preferably, the binder is present in an amount of from about 1 percent to
about 10 percent
by weight, preferably in an amount of from about 2 percent to about 9 percent
by weight, more
preferably in amount of between about 3 percent by weight and about 8 percent
by weight, on a
dry weight basis.
In certain embodiments, the homogenised tobacco material preferably comprises
between
about 1 percent and about 10 percent by weight of binder, on a dry weight
basis, wherein the
binder is most preferably guar gum. For example, in aerosol-generating
articles according to a
first preferred embodiment of the invention, the homogenised tobacco material
preferably
comprises between about 1 percent and about 10 percent by weight of binder, on
a dry weight
basis, wherein the binder is most preferably guar gum.
In certain embodiments, the homogenised tobacco material preferably comprises
between
about 2 percent and about 10 percent by weight of binder, on a dry weight
basis, wherein the
binder is most preferably cellulose ether. For example, in the aerosol-
generating articles
according to a second preferred embodiment, the homogenised tobacco material
preferably
comprises between about 2 percent and about 10 percent by weight of binder, on
a dry weight
basis, wherein the binder is preferably cellulose ether. Particularly
preferably, the binder is
carboxymethyl cellulose (CMC).
In addition, the homogenised tobacco material of any embodiment may optionally
further
comprise additional cellulose. For example, the homogenised tobacco material
may comprise
between about 5 percent by weight and about 50 percent by weight of additional
cellulose.
As used herein, the term "additional cellulose" encompasses any cellulosic
material
incorporated into the homogenised tobacco material which does not derive from
the tobacco
material provided in the homogenised tobacco material. The additional
cellulose is therefore
incorporated in the homogenised tobacco material in addition to the tobacco
material, as a
separate and distinct source of cellulose to any cellulose intrinsically
provided within the tobacco
material. The additional cellulose will typically derive from a different
plant to the tobacco material.
Preferably, the additional cellulose is in the form of an inert cellulosic
material, which is sensorially
inert and therefore does not substantially impact the organoleptic
characteristics of the aerosol
generated from the homogenised tobacco material. For example, the additional
cellulose is
preferably a tasteless and odourless material.
The additional cellulose may consist of one type of cellulose material, or may
be a
combination of different types of cellulose material which provide different
properties, as
described in more detail below.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-20-
The additional cellulose incorporated in the homogenised tobacco material
according to
the present invention is thought to provide additional structure and
reinforcement to bind and
support the plant material and aerosol former within the homogenised tobacco
material.
The incorporation of additional cellulose has been found to be particularly
beneficial in
homogenised tobacco materials in which the binder comprises cellulose ether,
as described
above. The combination of cellulose ether and additional cellulose material,
at certain defined
levels and within defined ratios, as set out below, has been advantageously
found to provide an
homogenised tobacco material having an improved tensile strength and
homogeneity.
Preferably, the ratio of additional cellulose material to cellulose ether in
the homogenised
tobacco material is at least 2.
Preferably, the additional cellulose comprises cellulose powder. The term
"cellulose
powder" is used herein to refer to a refined cellulose material in powder form
that has been derived
from cellulose fibres. Preferably, the cellulose powder is formed of particles
with an average
particle size of less than 100 microns. The cellulose powder may be in the
form of microcrystalline
cellulose. A suitable cellulose powder for use in the present invention is
available as
Microcrystalline Cellulose Type SK-105 or SK-101, or Cellulose Powder Type M-
60 from Gumix
International, Inc. of New Jersey.
Preferably, the amount of cellulose powder corresponds to at least about 5
percent by
weight of the homogenised tobacco material, more preferably at least about 6
percent by weight
of the homogenised tobacco material, more preferably at least about 7 percent
by weight of the
homogenised tobacco material and more preferably at least about 8 percent by
weight of the
homogenised tobacco material, on a dry weight basis.
The amount of cellulose powder may be adapted above this minimum level
depending
upon the weight amount of the other components within the homogenised tobacco
material and
in particular, depending upon the weight amount of the plant material. In
certain embodiments,
the cellulose powder may replace a proportion of the plant material within the
homogenised
tobacco material, without a significant impact on the characteristics of the
aerosol generated.
Preferably, the amount of cellulose powder corresponds to no more than about
45 percent
by weight of the homogenised tobacco material, more preferably no more than
about 40 percent
by weight of the homogenised tobacco material, on a dry weight basis.
In certain embodiments, for example, embodiments having a relatively high
level of plant
material in the homogenised tobacco material, the amount of cellulose powder
may be relatively
low. In such embodiments, the amount of cellulose powder may be between about
5 percent by
weight and about 15 percent by weight of the homogenised tobacco material, or
between about
6 percent by weight and about 12 percent by weight of the homogenised tobacco
material, or
between about 7 percent by weight and about 11 percent by weight of the
homogenised tobacco
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-21-
material, or between about 8 percent by weight and about 10 percent by weight
of the
homogenised tobacco material, on a dry weight basis.
In other embodiments, for example, embodiments having a relatively low level
of aerosol-
generating plant material in the homogenised tobacco material, the amount of
cellulose powder
may be relatively high. In such embodiments, the amount of cellulose powder
may be between
about 15 percent by weight and about 45 percent by weight of the homogenised
tobacco material,
or between about 20 percent by weight and about 40 percent by weight of the
homogenised
tobacco material, or between about 25 percent by weight and about 35 percent
by weight of the
homogenised tobacco material, on a dry weight basis.
Preferably, where the homogenised tobacco material comprises cellulose ether
and
cellulose powder, the ratio by weight of cellulose powder to cellulose ether
in the homogenised
tobacco material is at least about 1.5, i.e. the amount of cellulose powder is
at least 1.5 times the
amount of cellulose ether. More preferably, the ratio by weight of cellulose
powder to cellulose
ether in the homogenised tobacco material is at least about 1.6, more
preferably at least about
1.8.
Alternatively or in addition to the cellulose powder, the additional cellulose
may comprise
cellulose fibres. The term "cellulose fibres" is used herein to refer to
fibres obtained directly from
plant-based materials, wherein each fibre has a length that is significantly
greater than its width.
The cellulose fibres preferably have a fibre length of at least 400 microns.
Suitable cellulose
fibres for use in the present invention include, for example, wood pulp
fibres. A suitable source
of cellulose fibres for use in the present invention is available as ECF
Bleached Hardwood Kraft
Pulp from Storaenso, Sweden.
The cellulose fibres may advantageously act as mechanical reinforcement in the
homogenised tobacco material forming the aerosol-generating substrate of
aerosol-generating
articles according to the invention. The cellulose fibres may improve the
binding of the plant
material in the homogenised tobacco material and provide an improvement in
tensile strength, in
particular when combined with a cellulose ether binder.
Preferably, the amount of cellulose fibres corresponds to at least about 3
percent by weight
of the homogenised tobacco material, based on dry weight, more preferably at
least about 4
percent by weight of the homogenised tobacco material, more preferably at
least about 5 percent
by weight homogenised tobacco material and more preferably at least about 6
percent by weight
homogenised tobacco material, on a dry weight basis.
Preferably, the amount of cellulose fibres corresponds to no more than about
12 percent
by weight of the homogenised tobacco material, more preferably at least about
11 percent by
weight of the homogenised tobacco material, more preferably at least about 10
percent by weight
of the homogenised tobacco material, more preferably at least about 8 percent
by weight of the
homogenised tobacco material, on a dry weight basis.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-22-
For example, the homogenised tobacco material may comprise between about 3
percent
by weight and about 12 percent by weight of cellulose fibres, or between about
4 percent by
weight and about 11 percent by weight of cellulose fibres, or between about 5
percent by weight
and about 10 percent by weight of cellulose fibres, or between about 6 percent
by weight and
about 8 percent by weight of cellulose fibres, on a dry weight basis.
Preferably, where the homogenised tobacco material comprises cellulose ether
and
cellulose fibres, the ratio by weight of cellulose fibres to cellulose ether
in the homogenised
tobacco material is at least about 0.5, La the amount of cellulose powder is
at least half the
amount of cellulose ether. More preferably, the ratio by weight of cellulose
fibres to cellulose
ether in the homogenised tobacco material is at least about 0.75, more
preferably at least about
1.
In preferred embodiments, the additional cellulose comprises cellulose powder
and
cellulose fibres. In such embodiments, the ratio by weight of cellulose powder
to cellulose fibres
is preferably at least about 1.5, more preferably at least about 1.75, more
preferably at least about
2.
Preferably, the amount of additional cellulose provided in the homogenised
tobacco
material is adapted such that the total amount of additional cellulose and
plant material
corresponds to no more than 75 percent by weight of the homogenised tobacco
material.
Preferably, at least about 25 percent by weight of the homogenised tobacco
material is therefore
provided by other components, including the cellulose ether and aerosol
former.
In the aerosol-generating articles according to the second preferred
embodiment of the
present invention, the homogenised tobacco material preferably comprises
between about 2
percent and about 10 percent by weight of cellulose ether and between about 5
percent by weight
and about 50 percent by weight of additional cellulose, on a dry weight basis.
Preferably, the
ratio of the additional cellulose to cellulose ether is at least 2.
In addition to the components described above, the homogenised tobacco
material may
optionally further comprise one or more lipids to facilitate the diffusivity
of volatile components (for
example, aerosol formers and nicotine), wherein the lipid is included in the
homogenised plant
material during manufacturing as described herein.
Suitable lipids for inclusion in the
homogenised tobacco material include, but are not limited to: medium-chain
triglycerides, cocoa
butter, palm oil, palm kernel oil, mango oil, shea butter, soybean oil,
cottonseed oil, coconut oil,
hydrogenated coconut oil, candellila wax, carnauba wax, shellac, sunflower
wax, sunflower oil,
rice bran, and Revel A; and combinations thereof.
Alternatively or in addition, the homogenised tobacco material may further
comprise a pH
modifier.
Alternatively or in addition, the homogenised tobacco material may further
comprise fibres
to alter the mechanical properties of the homogenised tobacco material,
wherein the fibres are
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-23-
included in the homogenised tobacco material during manufacturing as described
herein.
Suitable exogenous fibres for inclusion in the homogenised tobacco material
are known in the art
and include fibres formed from non-tobacco material and non-tobacco material,
including but not
limited to: cellulose fibres; soft-wood fibres; hard-wood fibres; jute fibres
and combinations
thereof. Exogenous fibres derived from tobacco and/or tobacco can also be
added. Any fibres
added to the homogenised tobacco material are not considered to form part of
the "plant material"
as defined above. Prior to inclusion in the homogenised tobacco material,
fibres may be treated
by suitable processes known in the art including, but not limited to:
mechanical pulping; refining;
chemical pulping; bleaching; sulphate pulping; and combinations thereof. A
fibre typically has a
length greater than its width.
Suitable fibres typically have lengths of greater than 400 micrometres and
less than or equal
to 4 mm, preferably within the range of 0.7 mm to 4 mm. Preferably, the fibres
are present in an
amount of at least about 2 percent by weight, based on the dry weight of the
substrate. The
amount of fibres in the homogenised tobacco material may depend upon the type
of material and
in particular, the method that is used to produce the homogenised tobacco
material. In some
embodiments, the fibres may be present in an amount of between about 2 percent
by weight and
about 15 percent by weight, most preferably at about 4 percent by weight,
based on the dry weight
of the substrate. For example, this level of fibres may be present where the
homogenised tobacco
material is in the form of cast leaf. In other embodiments, the fibres may be
present in an amount
of at least about 30 percent by weight, or at least about 40 percent by
weight. For example, this
higher level of fibres is likely to be provided where the homogenised tobacco
material is a tobacco
paper formed in a papermaking process.
In preferred embodiments of the invention, the homogenised tobacco material
comprises
between about 5 percent by weight and about 30 percent by weight of aerosol
former and between
about 1 percent by weight and about 10 percent by weight of binder, on a dry
weight basis. In
such embodiments, the homogenised tobacco material preferably further
comprises between
about 2 percent by weight and about 15 percent by weight of fibres.
Particularly preferably, the
binder is guar gum.
The homogenised tobacco material is preferably in the form of a solid or a
gel. However,
in some embodiments the homogenised tobacco material may be in the form of a
solid that is not
a gel. Preferably, the homogenised tobacco material is not in the form of a
film.
The homogenised tobacco material can be provided in any suitable form. For
example,
the homogenised tobacco material may be in the form of one or more sheets. As
used herein
with reference to the invention, the term "sheet" describes a laminar element
having a width and
length substantially greater than the thickness thereof.
Alternatively or in addition, the homogenised tobacco material may be in the
form of a
plurality of pellets or granules.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-24-
Alternatively or in addition, the homogenised tobacco material may be in a
form that can
fill a cartridge or a shisha consumable, or that can be used in a shisha
device. The invention
includes a cartridge or a shisha device that contains an homogenised tobacco
material.
Alternatively or in addition, the homogenised tobacco material may be in the
form of a
plurality of strands, strips or shreds. As used herein, the term "strand"
describes an elongate
element of material having a length that is substantially greater than the
width and thickness
thereof. The term "strand" should be considered to encompass strips, shreds
and any other
homogenised tobacco material having a similar form. The strands of homogenised
tobacco
material may be formed from a sheet of homogenised tobacco material, for
example by cutting or
shredding, or by other methods, for example, by an extrusion method.
In some embodiments, the strands may be formed in situ within the homogenised
tobacco
material as a result of the splitting or cracking of a sheet of homogenised
tobacco material during
formation of the homogenised tobacco material, for example, as a result of
crimping. The strands
of homogenised tobacco material within the homogenised tobacco material may be
separate from
each other. Alternatively, each strand of homogenised tobacco material within
the homogenised
tobacco material may be at least partially connected to an adjacent strand or
strands along the
length of the strands. For example, adjacent strands may be connected by one
or more fibres.
This may occur, for example, where the strands have been formed due to the
splitting of a sheet
of homogenised tobacco material during production of the homogenised tobacco
material, as
described above.
Preferably, the homogenised tobacco material is in the form of one or more
sheets of
homogenised tobacco material. In various embodiments of the invention, the one
or more sheets
of homogenised tobacco material may be produced by a casting process. In
various
embodiments of the invention, the one or more sheets of homogenised tobacco
material may be
produced by a paper-making process. The one or more sheets as described herein
may each
individually have a thickness of between 100 micrometres and 600 micrometres,
preferably
between 150 micrometres and 300 micrometres, and most preferably between 200
micrometres
and 250 micrometres. Individual thickness refers to the thickness of the
individual sheet, whereas
combined thickness refers to the total thickness of all sheets that make up
the aerosol-generating
substrate. For example, if the aerosol-generating substrate is formed from two
individual sheets,
then the combined thickness is the sum of the thickness of the two individual
sheets or the
measured thickness of the two sheets where the two sheets are stacked in the
aerosol-generating
substrate.
The one or more sheets as described herein may each individually have a
grammage of
between about 100 g/m2 and about 300 g/m2, or between about 100 g/m2 and about
200 g/m2.
The one or more sheets as described herein may each individually have a
density of from
about 0.3 g/cm3to about 1.3 g/cm3, and preferably from about 0.7 g/cm3 to
about 1.0 g/cm3.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-25-
In embodiments of the present invention in which the aerosol-generating
substrate
comprises one or more sheets of homogenised tobacco material, the sheets are
preferably in the
form of one or more gathered sheets. As used herein, the term "gathered"
denotes that the sheet
of homogenised tobacco material is convoluted, folded, or otherwise compressed
or constricted
substantially transversely to the cylindrical axis of a plug or a rod. The
step of "gathering" the
sheet may be carried out by any suitable means which provides the necessary
transverse
compression of the sheet.
As used herein, the term "longitudinal" refers to the direction corresponding
to the main
longitudinal axis of the aerosol-generating article, which extends between the
upstream and
downstream ends of the aerosol-generating article. During use, air is drawn
through the aerosol-
generating article in the longitudinal direction. The term "transverse" refers
to the direction that is
perpendicular to the longitudinal axis. As used herein, the term "length"
refers to the dimension
of a component in the longitudinal direction and the term "width" refers to
the dimension of a
component in the transverse direction. For example, in the case of a plug or
rod having a circular
cross-section, the maximum width corresponds to the diameter of the circle.
As used herein, the term "plug" denotes a generally cylindrical element having
a
substantially polygonal, circular, oval or elliptical cross-section. As used
herein, the term "rod"
refers to a generally cylindrical element of substantially polygonal cross-
section and preferably of
circular, oval or elliptical cross-section. A rod may have a length greater
than or equal to the
length of a plug. Typically, a rod has a length that is greater than the
length of a plug. A rod may
comprise one or more plugs, preferably aligned longitudinally.
As used herein, the terms "upstream" and "downstream" describe the relative
positions of
elements, or portions of elements, of the aerosol-generating article in
relation to the direction in
which the aerosol is transported through the aerosol-generating article during
use. The
downstream end of the airflow path is the end at which aerosol is delivered to
a user of the article.
The one or more sheets of homogenised tobacco material may be gathered
transversely
relative to the longitudinal axis thereof and circumscribed with a wrapper to
form a continuous rod
or a plug. The continuous rod may be severed into a plurality of discrete rods
or plugs. The
wrapper may be a paper wrapper or a non-paper wrapper, as described in more
detail below.
tobacco
Alternatively, the one or more sheets of homogenised tobacco material may be
cut into
strands as referred to above. In such embodiments, the aerosol-generating
substrate comprises
a plurality of strands of the homogenised tobacco material. The strands may be
used to form a
plug. Typically, the width of such strands is at least about 0.2 mm, or at
least about 0.5 mm.
Preferably, the width of such strands is no more than about 5 mm, or about
4mm, or about 3 mm,
or about 1.5 mm. For example, the width of the strands may be between about
0.25 mm and
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-26-
about 5 mm, or between about 0.25 mm and about 3 mm, or between about 0.5 mm
and about
1.5 mm.
The length of the strands is preferably greater than about 5 mm, for example,
between
about 5 mm to about 20 mm, or between about 8 mm to about 15 mm, or about 12
mm. Preferably,
the strands have substantially the same length as each other. The length of
the strands may be
determined by the manufacturing process whereby a rod is cut into shorter
plugs and the length
of the strands corresponds to the length of the plug. The strands may be
fragile which may result
in breakage especially during transit. In such cases, the length of some of
the strands may be
less than the length of the plug.
The plurality of strands preferably extend substantially longitudinally along
the length of the
aerosol-generating substrate, aligned with the longitudinal axis. Preferably,
the plurality of
strands are therefore aligned substantially parallel to each other.
The strands of homogenised tobacco material preferably each have a mass to
surface area
ratio of at least about 0.02 milligrams per square millimetre, more preferably
at least about 0.05
milligrams per square millimetre. Preferably the strands of homogenised
tobacco material each
have a mass to surface area ratio of no more than about 0.2 milligrams per
square millimetre,
more preferably no more than about 0.15 milligrams per square millimetre. The
mass to surface
area ratio is calculated by dividing the mass of the strand of homogenised
tobacco material in
milligrams by the geometric surface area of the strand of homogenised tobacco
material in square
millimetres.
The one or more sheets of homogenised tobacco material may be textured through
crimping, embossing, or perforating. The one or more sheets may be textured
prior to gathering
or prior to being cut into strands. Preferably, the one or more sheets of
homogenised tobacco
material are crimped prior to gathering, such that the homogenised tobacco
material may be in
the form of a crimped sheet, more preferably in the form of a gathered crimped
sheet. As used
herein, the term "crimped sheet" denotes a sheet having a plurality of
substantially parallel ridges
or corrugations usually aligned with the longitudinal axis of the article.
In one embodiment, the aerosol-generating substrate may be in the form of a
single plug of
homogenised tobacco material. In other embodiments, the aerosol-generating
substrate may be
in the form of two or more plugs of homogenised tobacco material, wherein the
plugs of
homogenised tobacco material may be formed from the same or a different
homogenised tobacco
material.
The aerosol-generating substrates according to the invention may be produced
by various
methods including paper making, casting, dough reconstitution, extrusion or
any other suitable
process. Preferably, the aerosol-generating substrate is a homogenised tobacco
material.
Preferably, the homogenised tobacco material is in the form of "cast leaf".
The term "cast
leaf" is used herein to refer to a sheet product made by a casting process
that is based on casting
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-27-
a slurry comprising tobacco particles and a binder (for example, guar gum)
onto a supportive
surface, such as a belt conveyor, drying the slurry and removing the dried
sheet from the
supportive surface. An example of the casting or cast leaf process is
described in, for example,
US-A-5,724,998 for making cast leaf tobacco. In a cast leaf process,
particulate plant materials
are mixed with a liquid component, typically water, to form a slurry. Other
added components in
the slurry may include fibres, a binder and an aerosol former. The particulate
plant materials may
be agglomerated in the presence of the binder. The slurry is cast onto a
supportive surface and
dried to form a sheet of homogenised tobacco material.
In certain preferred embodiments, the homogenised tobacco material used in
articles
according to the present invention is produced by casting. Homogenised tobacco
material made
by the casting process typically comprise agglomerated particulate plant
material.
In a cast-leaf process, because substantially all the soluble fraction is kept
within the plant
material, most flavours are advantageously preserved. Additionally, energy-
intensive paper-
making steps are avoided.
In one preferred embodiment of the present invention, to form homogenised
tobacco
material, a mixture comprising particulate plant material, water, a binder,
and an aerosol former
is formed. A sheet is formed from the mixture, and the sheet is then dried.
Preferably the mixture
is an aqueous mixture. As used herein, "dry weight" refers to the weight of a
particular non-water
component relative to the sum of the weights of all non-water components in a
mixture, expressed
as a percentage. The composition of aqueous mixtures may be referred to by
"percentage dry
weight." This refers to the weight of the non-water components relative to the
weight of the entire
aqueous mixture, expressed as a percentage.
The mixture may be a slurry. As used herein, a "slurry" is a homogenised
aqueous mixture
with a relatively low dry weight. A slurry as used in the method herein may
preferably have a dry
weight of between 5 percent and 60 percent.
Alternatively, the mixture may be a dough. As used herein, a "dough" is an
aqueous mixture
with a relatively high dry weight. A dough as used in the method herein may
preferably have a
dry weight of at least 60 percent, more preferably at least 70 percent.
Slurries comprising greater than 30 percent dry weight and doughs may be
preferred in
certain embodiments of the present method.
The step of mixing the particulate plant material, water and other optional
components may
be carried out by any suitable means. For mixtures of a low viscosity, that
is, some slurries, it is
preferred that mixing is performed using a high energy mixer or a high shear
mixer. Such mixing
breaks down and distributes the various phases of the mixture homogeneously.
For mixtures of
a higher viscosity, that is, some doughs, a kneading process may be used to
distribute the various
phases of the mixture homogeneously.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-28-
Methods according to the present invention may further comprise the step of
vibrating the
mixture to distribute the various components. Vibrating the mixture, that is
for example vibrating
a tank or silo where a homogenised mixture is present, may help the
homogenization of the
mixture, particularly when the mixture is a mixture of low viscosity, that is,
some slurries. Less
mixing time may be required to homogenize a mixture to the target value
optimal for casting if
vibrating is performed as well as mixing.
If the mixture is a slurry, a web of homogenised tobacco material is
preferably formed by a
casting process comprising casting the slurry on a supportive surface, such as
a belt conveyor.
The method for production of a homogenised tobacco material comprises the step
of drying said
cast web to form a sheet. The cast web may be dried at room temperature or at
an ambient
temperature of at least about 60 degrees Celsius, more preferably at least
about 80 degrees
Celsius for a suitable length of time. Preferably, the cast web is dried at an
ambient temperature
of no more than 200 degrees Celsius, more preferably no more than about 160
degrees Celsius.
For example, the cast web may be dried at a temperature of between about 60
degrees Celsius
and about 200 degrees Celsius, or between about 80 degrees Celsius and about
160 degrees
Celsius. Preferably, the moisture content of the sheet after drying is between
about 5 percent
and about 15 percent based on the total weight of the sheet. The sheet may
then be removed
from the supportive surface after drying. The cast sheet has a tensile
strength such that it can be
mechanically manipulated and wound or unwound from a bobbin without breakage
or
deformation.
If the mixture is a dough, the dough may be extruded in the form of a sheet,
strands, or
strips, prior to the step of drying the extruded mixture. Preferably, the
dough may be extruded in
the form of a sheet. The extruded mixture may be dried at room temperature or
at a temperature
of at least about 60 degrees Celsius, more preferably at least about 80
degrees Celsius for a
suitable length of time. Preferably, the extruded mixture is dried at an
ambient temperature of no
more than 200 degrees Celsius, more preferably no more than about 160 degrees
Celsius. For
example, the extruded mixture may be dried at a temperature of between about
60 degrees
Celsius and about 200 degrees Celsius, or between about 80 degrees Celsius and
about 160
degrees Celsius. Preferably, the moisture content of the extruded mixture
after drying is between
about 5 percent and about 15 percent based on the total weight of the sheet. A
sheet formed
from dough requires less drying time and/or lower drying temperatures as a
result of significantly
lower water content relative to a web formed from a slurry.
After the sheet has been dried, the method may optionally comprise a step of
coating a
nicotine salt, preferably along with an aerosol former, onto the sheet, as
described in the
disclosure of WO-A-2015/082652.
After the sheet has been dried, methods according to the invention may
optionally
comprise a step of cutting the sheet into strands, shreds or strips for the
formation of the aerosol-
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-29-
generating substrate as described above. The strands, shreds or strips may be
brought together
to form a rod of the aerosol-generating substrate using suitable means. In the
formed rod of
aerosol-generating substrate, the strands, shreds or strips may be
substantially aligned, for
example, in the longitudinal direction of the rod. Alternatively, the strands,
shreds or strips may
be randomly oriented in the rod.
Methods according to the present invention may optionally further comprise a
step of
winding the sheet onto a bobbin, after the drying step.
The homogenised tobacco material of the present invention may alternatively be
produced
by a paper-making method for producing sheets of homogenised plant material in
the form of a
plant "paper". Plant paper refers to a reconstituted plant sheet formed by a
process in which a
plant feedstock is extracted with a solvent to produce an extract of soluble
plant compounds and
an insoluble residue of fibrous plant material, and the extract is recombined
with the insoluble
residue. The extract may optionally be concentrated or further processed
before being
recombined with the insoluble residue. The insoluble residue may optionally be
refined and
combined with additional plant fibres before being recombined with the
extract. In the method
according to the present invention, the plant feedstock will comprise
particles of tobacco,
optionally in combination with particles of tobacco.
In more detail, the method of producing a plant paper comprises a first step
of mixing a
plant material and water to form a dilute suspension. The dilute suspension
comprises mostly
separate cellulose fibres. The suspension has a lower viscosity and a higher
water content than
the slurry produced in the casting process. This first step may involve
soaking, optionally in the
presence of an alkali, such as sodium hydroxide, and optionally applying heat.
The method further comprises a second step of separating the suspension into
an
insoluble portion containing the insoluble residue of fibrous plant material
and a liquid or aqueous
extract comprising soluble plant compounds. The water remaining in the
insoluble residue of
fibrous plant material may be drained through a screen, acting as a sieve,
such that a web of
randomly interwoven fibres may be laid down. Water may be further removed from
this web by
pressing with rollers, sometimes aided by suction or vacuum.
After removal of the aqueous portion and water, the insoluble residue is
formed into a
sheet. Preferably, a generally flat, uniform sheet of plant fibres is formed.
Preferably, the method further comprises the steps of concentrating the
extract of soluble
plant compounds that were removed from the sheet and adding the concentrated
extract into the
sheet of insoluble residue of fibrous plant material to form a sheet of
homogenised plant material.
Alternatively or in addition, a soluble plant substance or concentrated plant
substance from
another process can be added to the sheet. The extract or concentrated extract
may be from
another variety of the same species of plant, or from another species of
plant.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-30-
This process, as described in US-A-3,860,012, has been used with tobacco to
make
reconstituted tobacco products, also known as tobacco paper.
In certain preferred embodiments, the homogenised tobacco material used in
articles
according to the present invention is produced by a paper-making process as
defined above. In
such embodiments, the homogenised tobacco material is in the form of a tobacco
paper.
Homogenised tobacco material produced by such a process is referred to as
tobacco
paper. Homogenised tobacco material made by the paper-making process is
distinguishable by
the presence of a plurality of fibres throughout the material, visible by eye
or under a light
microscope, particularly when the paper is wetted by water. In contrast,
homogenised tobacco
material made by the casting process comprises less fibres than paper and
tends to dissociate
into a slurry when it is wetted.
Other known processes that can be applied to producing homogenised tobacco
materials
are dough reconstitution processes of the type described in, for example, US-A-
3,894,544; and
extrusion processes of the type described in, for example, in GB-A-983,928.
Typically, the
densities of homogenised tobacco materials produced by extrusion processes and
dough
reconstitution processes are greater than the densities of the homogenised
tobacco materials
produced by casting processes.
Preferably, the aerosol-generating substrate of aerosol-generating articles
according to
the invention comprises at least about 200 mg of homogenised tobacco material,
more preferably
at least about 220 mg of homogenised tobacco material and more preferably at
least about 250
mg of homogenised tobacco material.
Aerosol-generating articles according to the invention comprise a rod,
comprising the
homogenised tobacco material in one or more plugs. The rod of aerosol-
generating substrate
may have a length of from about 5 mm to about 120 mm. For example, the rod may
preferably
have a length of between about 10 and about 45 mm, more preferably between
about 10 mm and
15 mm, most preferably about 12 mm. In alternative embodiments, the rod
preferably has a
length of between about 30 mm and about 45 mm, or between about 33 mm and
about 41 mm.
Where the rod is formed of a single plug of homogenised tobacco material, the
plug has the same
length as the rod.
The rod of aerosol-generating substrate may have an external diameter of
between about
5 mm and about 10 mm, depending on their intended use. For example, in some
embodiments,
the rod may have an external diameter of between about 5.5 mm and about 8 mm,
or between
about 6.5 mm and about 8 mm. The "external diameter" of the rod of aerosol-
generating substrate
corresponds to the diameter of the rod including any wrappers.
The rod of aerosol-generating substrate of the aerosol-generating articles
according to the
invention is preferably circumscribed by one or more wrappers along at least a
part of its length.
The one or more wrappers may include a paper wrapper or a non-paper wrapper,
or both.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-31-
Suitable paper wrappers for use in specific embodiments of the invention are
known in the art and
include, but are not limited to: cigarette papers; and filter plug wraps.
Suitable non-paper
wrappers for use in specific embodiments of the invention are known in the art
and include, but
are not limited to sheets of homogenised tobacco materials.
In certain embodiments of the invention, the aerosol-generating substrate is
circumscribed
along at least a part of its length by a thermally conductive sheet material,
for example, a metallic
foil, such as aluminium foil or a metallised paper. The metallic foil or
metallised paper serves the
purpose of conducting heat rapidly throughout the aerosol-generating
substrate. In addition, the
metallic foil or metallised paper may serve to prevent the ignition of the
aerosol-generating
substrate in the event that the consumer attempts to light it. Furthermore,
during use, the metallic
foil or metallised paper may prevent odours produced upon heating of the outer
wrapper from
entering the aerosol generated from the aerosol-generating substrate. For
example, this may be
a problem for aerosol-generating articles having an aerosol-generating
substrate that is heated
externally during use in order to generate an aerosol. Alternatively, or in
addition, a metallised
wrapper may be used to facilitate detection or recognition of the aerosol-
generating article when
it is inserted into an aerosol-generating device during use. The metallic foil
or metallised paper
may comprise metal particles, such as iron particles.
The one or more wrappers circumscribing the aerosol-generating substrate
preferably have
a total thickness of between about 0.1 mm and about 0.9 mm.
The internal diameter of the rod of aerosol-generating substrate is preferably
between about
3 mm and about 9.5 mm, more preferably between about 4 mm and about 7.5 mm,
more
preferably between about 5 mm and about 7.5 mm. The "internal diameter"
corresponds to the
diameter of the rod of aerosol-generating substrate without including the
thickness of the
wrappers, but measured with the wrappers still in place.
Aerosol-generating articles according to the invention also include but are
not limited to a
cartridge or a shisha consumable.
Aerosol-generating articles according to the invention may optionally comprise
at least one
hollow tube immediately downstream of the aerosol-generating substrate. One
function of the
tube is to locate the aerosol-generating substrate towards the distal end of
the aerosol-generating
article so that it can be contacted with a heating element. The tube acts to
prevent the aerosol-
generating substrate from being forced along the aerosol-generating article
towards other
downstream elements when a heating element is inserted into the aerosol-
generating substrate.
The tube also acts as a spacer element to separate the downstream elements
from the aerosol-
generating substrate. The tube can be made of any material, such as cellulose
acetate, a polymer,
cardboard, or paper.
Aerosol-generating articles according to the invention optionally comprise one
or more of a
spacer or an aerosol-cooling element downstream of the aerosol-generating
substrate and
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-32-
immediately downstream of the hollow tube. In use, an aerosol formed by
volatile compounds
released from the aerosol-generating substrate passes through and is cooled by
the aerosol-
cooling element before being inhaled by a user. The lower temperature allows
the vapours to
condense into an aerosol. The spacer or aerosol-cooling element may be a
hollow tube, such as
a hollow cellulose acetate tube or a cardboard tube, which can be similar to
the one that is
immediately downstream of the aerosol-generating substrate. The spacer may be
a hollow tube
of equal outer diameter but smaller or larger inner diameter than the hollow
cellulose acetate tube.
In one embodiment, the aerosol-cooling element wrapped in paper comprises one
or more
longitudinal channels made of any suitable material, such as a metallic foil,
a paper laminated
with a foil, a polymeric sheet preferably made of a synthetic polymer, and a
substantially non-
porous paper or cardboard. In some embodiments, the aerosol-cooling element
wrapped in paper
may comprise one or more sheets made of a material selected from the group
consisting of
polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyethylene
terephthalate
(PET), polylactic acid (PLA), cellulose acetate (CA), paper laminated with a
polymeric sheet and
aluminium foil. Alternatively, the aerosol-cooling element may be made of
woven or non-woven
filaments of a material selected from the group consisting of polyethylene
(PE), polypropylene
(PP), polyvinylchloride (PVC), polyethylene terephthalate (PET), polylactic
acid (PLA), and
cellulose acetate (CA). In a preferred embodiment, the aerosol-cooling element
is a crimped and
gathered sheet of polylactic acid wrapped within a filter paper. In another
preferred embodiment,
the aerosol-cooling element comprises a longitudinal channel and is made of
woven filaments of
a synthetic polymer, such as polylactic acid filaments, which are wrapped in
paper.
Aerosol-generating articles according to the invention may further comprise a
filter or
mouthpiece downstream of the aerosol-generating substrate and the hollow
acetate tube, spacer
or aerosol-cooling element. The filter may comprise one or more filtration
materials for the
removal of particulate components, gaseous components, or a combination
thereof. Suitable
filtration materials are known in the art and include, but are not limited to:
fibrous filtration materials
such as, for example, cellulose acetate tow and paper; adsorbents such as, for
example, activated
alumina, zeolites, molecular sieves and silica gel; biodegradable polymers
including, for example,
polylactic acid (P LA), Mater-Bi , hydrophobic viscose fibres, and
bioplastics; and combinations
thereof. The filter may be located at the downstream end of the aerosol-
generating article. The
filter may be a cellulose acetate filter plug. The filter is about 7 mm in
length in one embodiment,
but may have a length of between about 5 mm and about 10 mm.
Aerosol-generating articles according to the invention may comprise a mouth
end cavity at
the downstream end of the article. The mouth end cavity may be defined by one
or more wrappers
extending downstream from the filter or mouthpiece. Alternatively, the mouth
end cavity may be
defined by a separate tubular element provided at the downstream end of the
aerosol-generating
article.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-33-
Aerosol-generating articles according to the invention preferably further
comprise a
ventilation zone provided at a location along the aerosol-generating article.
For example, the
aerosol-generating article may be provided at a location along a hollow tube
provided downstream
of the aerosol-generating substrate.
In preferred embodiments of the invention, the aerosol-generating article
comprises the
aerosol-generating substrate, at least one hollow tube downstream of the
aerosol-generating
substrate and a filter downstream of the at least one hollow tube. Optionally,
the aerosol-
generating article further comprises a mouth end cavity at the downstream end
of the filter.
Preferably, a ventilation zone is provided at a location along the at least
one hollow tube.
The aerosol-generating articles according to the invention may have a total
length of at least
about 30 mm, or at least about 40 mm. The total length of the aerosol-
generating article may be
less than 90 mm, or less than about 80 mm.
In one embodiment, the aerosol-generating article has a total length of
between about 40
mm and about 50 mm, preferably about 45 mm. In another embodiment, the aerosol-
generating
article has a total length of between about 70 mm and about 90 mm, preferably
between about
80 mm and about 85 mm. in another embodiment, the aerosol-generating article
has a total
length of between about 72 mm and about 76 mm, preferably about 74 mm.
The aerosol-generating article may have an external diameter of about 5 mm to
about 8
mm, preferably between about 6 mm and about 8 mm. In one embodiment, the
aerosol-
generating article has an external diameter of about 7.3 mm.
Aerosol-generating articles according to the invention may further comprise
one or more
aerosol-modifying elements. An aerosol-modifying element may provide an
aerosol-modifying
agent. As used herein, the term aerosol-modifying agent is used to describe
any agent that, in
use, modifies one or more features or properties of aerosol passing through
the filter. Suitable
aerosol-modifying agents include, but are not limited to, agents that, in use,
impart a taste or
aroma to aerosol passing through the filter or agents that, in use, remove
flavours from the aerosol
passing through the filter.
An aerosol-modifying agent may be one or more of moisture or a liquid
flavourant. Water
or moisture may modify the sensorial experience of the user, for example by
moistening the
generated aerosol, which may provide a cooling effect on the aerosol and may
reduce the
perception of harshness experienced by the user. An aerosol-modifying element
may be in the
form of a flavour-delivery element to deliver one or more liquid flavourants.
Alternatively, a liquid
flavourant may be added directly to the homogenised plant material, for
example, by adding the
flavour to the slurry or feedstock during production of the homogenised plant
material, or by
spraying the liquid flavourant onto the surface of the homogenised plant
material.
The one or more liquid flavourants may comprise any flavour compound or
botanical extract
suitable for being releasably disposed in liquid form within the flavour-
delivery element to enhance
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-34-
the taste of aerosol produced during use of the aerosol-generating article.
The flavourants, liquid
or solid, can also be disposed directly in the material which forms the
filter, such as cellulose
acetate tow. Suitable flavours or flavourings include, but are not limited to,
menthol, mint, such as
peppermint and spearmint, chocolate, liquorice, citrus and other fruit
flavours, gamma
octalactone, vanillin, ethyl vanillin, breath freshener flavours, spice
flavours such as cinnamon,
methyl salicylate, linalool, eugenol, bergamot oil, geranium oil, lemon oil,
cannabis oil, and
tobacco flavour. Other suitable flavours may include flavour compounds
selected from the group
consisting of an acid, an alcohol, an ester, an aldehyde, a ketone, a
pyrazine, combinations or
blends thereof and the like.
An aerosol-modifying agent may be an adsorbent material such as activated
carbon, which
removes certain constituents of the aerosol passing through the filter and
thereby modifies the
flavour and aroma of the aerosol.
The one or more aerosol-modifying elements may be located downstream of the
aerosol-
generating substrate or within the aerosol-generating substrate. The aerosol-
generating
substrate may comprise homogenised tobacco material and an aerosol-modifying
element. In
various embodiments, the aerosol-modifying element may be placed adjacent to
the
homogenised tobacco material or embedded in the homogenised tobacco material.
Typically,
aerosol-modifying elements may be located downstream of the aerosol-generating
substrate,
most typically, within the aerosol-cooling element, within the filter of the
aerosol-generating article,
such as within a filter plug or within a cavity between filter plugs. The one
or more aerosol-
modifying elements may be in the form of one or more of a thread, a capsule, a
microcapsule, a
bead or a polymer matrix material, or a combination thereof.
If an aerosol-modifying element is in the form of a thread, as described in WO-
A-
2011/060961, the thread may be formed from paper such as filter plug wrap, and
the thread may
be loaded with at least one aerosol-modifying agent and located within the
body of the filter. Other
materials that can be used to form a thread include cellulose acetate and
cotton.
If an aerosol-modifying element is in the form of a capsule, as described in
WO-A-
2007/010407, WO-A-2013/068100 and WO-A-2014/154887, the capsule may be a
breakable
capsule located within the filter, the inner core of the capsule containing an
aerosol-modifying
agent which may be released upon breakage of the outer shell of the capsule
when the filter is
subjected to external force. The capsule may be located within a filter plug
or within a cavity
between filter plugs.
If an aerosol-modifying element is in the form of a polymer matrix material,
the polymer
matrix material releases the flavourant when the aerosol-generating article is
heated, such as
when the polymer matrix is heated above the melting point of the polymer
matrix material as
described in WO-A-2013/034488. Typically, such polymer matrix material may be
located within
a bead within the aerosol-generating substrate. Alternatively, or in addition,
the flavourant may
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-35-
be trapped within the domains of a polymer matrix material and releasable from
the polymer
matrix material upon compression of the polymer matrix material. Preferably,
the flavourant is
released upon compression of the polymer matrix material with a force of
around 15 Newtons.
Such flavour-modifying elements may provide a sustained release of the liquid
flavourant over a
range of force of at least 5 Newtons, such as between 5N and 20N, as described
in
W02013/068304. Typically, such polymer matrix material may be located within a
bead within the
filter.
The aerosol-generating article may comprise a combustible heat source and an
aerosol-
generating substrate downstream of the combustible heat source, the aerosol-
generating
substrate as described above with respect to the first aspect of the
invention.
For example, substrates as described herein may be used in heated aerosol-
generating
articles of the type disclosed in WO-A-2009/022232, which comprise a
combustible carbon-based
heat source, an aerosol-generating substrate downstream of the combustible
heat source, and a
heat-conducting element around and in contact with a rear portion of the
combustible carbon-
based heat source and an adjacent front portion of the aerosol-generating
substrate. However,
it will be appreciated that substrates as described herein may also be used in
heated aerosol-
generating articles comprising combustible heat sources having other
constructions.
The present invention provides an aerosol-generating system comprising an
aerosol-
generating device comprising a heating element, and an aerosol-generating
article for use with
the aerosol-generating device, the aerosol-generating article comprising the
aerosol-generating
substrate as described above.
In a preferred embodiment, aerosol-generating substrates as described herein
may be
used in heated aerosol-generating articles for use in electrically-operated
aerosol-generating
systems in which the aerosol-generating substrate of the heated aerosol-
generating article is
heated by an electrical heat source.
For example, aerosol-generating substrates as described herein may be used in
heated
aerosol-generating articles of the type disclosed in EP-A-0 822 760.
The heating element of such aerosol-generating devices may be of any suitable
form to
conduct heat. The heating of the aerosol-generating substrate may be achieved
internally,
externally or both. The heating element may preferably be a heater blade or
pin adapted to be
inserted into the substrate so that the substrate is heated from inside.
Alternatively, the heating
element may partially or completely surround the substrate and heat the
substrate
circumferentially from the outside.
In certain embodiments of the invention, the aerosol-generating system
comprises an
aerosol-generating article comprising an aerosol-generating substrate as
defined above, a source
of aerosol former and a means to vaporise the aerosol former, preferably a
heating element as
described above. The source of aerosol former can be a reservoir, which can be
refillable or
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-36-
replaceable, that resides on the aerosol generating device. While the
reservoir is physically
separate from the aerosol generating article, the vapour that is generated is
directed through the
aerosol-generating article. The vapour makes contact with the aerosol-
generating substrate
which releases volatile compounds, such as nicotine and flavourants in the
plant material, to form
an aerosol. Optionally, to aid volatilization of compounds in the aerosol-
generating substrate, the
aerosol-generating system may further comprise a heating element to heat the
aerosol-
generating substrate, preferably in a co-ordinated manner with the aerosol
former. However, in
certain embodiments, the heating element used to heat the aerosol generating
article is separate
from the heater that heats the aerosol former.
As defined above, the present invention further provides a method for the
production of
dried green tobacco material for use in an aerosol-generating substrate
according to the invention,
as described in detail below. The method according to the invention includes
the following steps:
providing uncured green tobacco leaves; drying the uncured green tobacco
leaves until a moisture
content of between 4 percent by weight and 15 percent by weight is achieved;
and cutting or
grinding the uncured green tobacco leaves to produce dried green tobacco
material. According
to the invention, the temperature, pressure and duration of the drying step
are selected such that
the dried green tobacco material retains a chlorophyll level of at least 0.5
milligrams per gram.
This means that the drying step is carried out in such a way that the level of
chlorophyll in the
tobacco leaves is retained and the leaves remain green in colour. The green
tobacco leaves are
not subjected to any curing process.
Preferably, the drying step of the method according to the invention is
completed within
than 5 days from the harvesting of the uncured green tobacco leaves, more
preferably within 4
days from the harvesting, more preferably within 3 days from the harvesting
and most preferably
within 2 days from the harvesting. This means that the total storage and
drying time of the tobacco
material does not exceed 5 days, or 4 days, or 3 days or 2 days from the time
that the tobacco
material is harvested. The dried green tobacco material is therefore produced
within a relatively
short time after the harvesting of the tobacco, so that any effects on the
chemical composition of
the tobacco leaves as a result of storage of the tobacco leaves can be
minimised.
The method of the present invention provides a fast and efficient way to
process green
tobacco leaves into dried green tobacco material that is suitable for use in
an aerosol-generating
substrate for an aerosol-generating article, as described above. This in turn
enables an aerosol-
generating substrate to be produced more efficiently, both from a time and
cost perspective. The
method of the present invention can be applied to all tobacco types.
Advantageously, the method
of the present invention can be carried out on whole tobacco leaves, without
destemming, if
desired. Alternatively, the method according to the invention may be carried
out with the lamina
of the uncured green tobacco leaves. In this case, the leaves would be
destemmed prior to the
drying step and the stems processed separately. If desired, the stems may be
recombined with
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-37-
the tobacco lamina to provide the dried green tobacco material for forming the
aerosol-generating
substrate.
The drying of the green tobacco leaves is carried out with specifically
selected temperature
and pressure conditions so that curing does not occur and the tobacco leaves
retain their green
colour. As described above, there are several benefits to the use of green
tobacco leaves in an
aerosol-generating substrate, based on the reduced levels of certain
undesirable constituents that
are present in green tobacco leaves compared with cured leaves.
Several different methods are available for rapidly drying the uncured tobacco
leaves to
reduce the moisture content to between about 4 percent and about 15 percent by
weight, more
preferably between about 10 percent and about 13 percent by weight, whilst
retaining the
chlorophyll levels in the leaf as high as possible. Depending upon the method
selected, the
temperature, pressure and duration are specifically adapted to provide the
required outcome.
In certain embodiments, the drying step is carried out by heating the uncured
green
tobacco leaves to reduce the moisture content of the leaves as rapidly as
possible. Heating of
the tobacco leaves may be carried out using any suitable apparatus, such as an
oven or dryer,
which would be known to the skilled person. Preferably, the heating of the
tobacco leaves is
carried out in a tray dryer. An example of a suitable apparatus for carrying
out the drying step is
the tray dryer available from Wolvering Proctor & Schwartz Ltd.
In a tray dryer, the tobacco leaves are typically hung within the heating
chamber, which
minimises contact between leaves and maximises the surface area of the leaves
that is exposed,
in order to facilitate drying. During the drying step, heated air or steam is
circulated through the
chamber at the desired temperature. The use of a tray dryer for heating the
tobacco leaves has
been found to advantageously provide an even heating of the leaves, with
minimisation of hot
spots within the dryer. This optimises the uniformity of the drying of the
leaves. The use of a tray
dryer has also been found to be most effective for the drying of the midribs
of the tobacco leaves,
which typically dry more slowly than the lamina portions of the leaves.
Preferably, in such embodiments, the drying step is carried out at a
temperature of less
than about 120 degrees Celsius, more preferably at a temperature of less than
about 110 degrees
Celsius. Preferably, the drying step is carried out at a temperature of at
least about 75 degrees
Celsius, more preferably at least about 85 degrees Celsius and more preferably
at least about
100 degrees Celsius. For example, the drying step may be carried out at a
temperature of
between about 75 degrees Celsius and about 120 degrees Celsius, or between
about 75 degrees
and about 110 degrees Celsius. This temperature level is selected in order to
provide effective
drying whilst retaining a relatively high level of chlorophyll and avoiding
damage to the leaves
during the heating process.
In a particularly preferred embodiment, the drying step is carried out at a
temperature of
between 75 degrees Celsius and 110 degrees Celsius in a tray dryer.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-38-
The duration of the heating step will depend upon the moisture level of the
uncured
tobacco leaves prior to drying, as well as the specific temperature selected
for the heating step
and the exact heating conditions. Preferably, the tobacco leaves are heated
for no more than 7
hours, preferably no more than 6 hours, preferably no more than 4 hours, more
preferably no
more than 2 hours and most preferably no more than 1 hour.
In a particularly preferred example, the uncured tobacco leaves are heated at
a
temperature of 75 degrees Celsius for no more than 7 hours to achieve the
required reduction in
moisture content. In an alternative preferred example, the uncured tobacco
leaves are heated at
a temperature of 110 degrees Celsius for no more than 4 hours to achieve the
required reduction
in moisture content.
Preferably, the heating step is carried out under ventilated conditions, with
a continuous
flow of air or inert gas being passed through the tobacco leaves during
heating. This may
advantageously decrease the required drying time.
Preferably, the heating step is carried out without agitation of the tobacco
leaves, for
example, in a rotary drum. This avoids potential damage to the tobacco leaves
during heating.
The heating step may be carried out on the whole, intact tobacco leaves.
Alternatively,
the tobacco leaves may be destemmed prior to the heating steps such that the
tobacco lamina
and the tobacco stems are dried separately from each other.
In certain embodiments, the heating step comprises heating the whole tobacco
leaves,
separating the tobacco lamina from the tobacco stems when dry and removing the
tobacco lamina
from the dryer, then heating the remaining tobacco stems until dry. This
enables both the tobacco
lamina and mid rib to be effectively dried, without over-drying the lamina.
In certain embodiments in which the drying step is carried out by heating, the
method
according to the invention may further comprise a second heating step, which
is carried out after
the first heating step and at a lower temperature. For example, the method may
further comprise
a second heating step during which the uncured green tobacco leaves are heated
at a
temperature of less than about 75 degrees Celsius, or less than about 50
degrees Celsius. The
inclusion of a second heating step may be advantageous where the uncured
tobacco leaves are
kept intact during drying, so that complete drying of the tobacco stem (mid-
rib) can be achieved.
As an alternative to heating, the drying step of the method of the present
invention may
be carried out by lyophilisation. Lyophilisation, also known as freeze drying,
is a dehydration
process which involves freezing a product (in this case, the tobacco leaves)
and then
progressively reducing the pressure and increasing the temperature in order to
sublimate the
frozen water and thereby remove it from the product.
Preferably, during drying of the uncured green tobacco leaves by
lyophilisation, the
tobacco leaves are initially frozen to a temperature of less than minus 60
degrees, more preferably
less than minus 75 degrees Celsius. For example, the tobacco leaves may be
frozen to a
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-39-
temperature of about minus 80 degrees Celsius. Preferably, the freezing of the
tobacco leaves
is carried out as soon after the harvesting of the leaves as possible.
The remaining steps of the lyophilisation process are carried out in a
suitable lyophilisation
chamber. In a first lyophilisation phase, the uncured tobacco leaves are
preferably retained in a
frozen state at atmospheric pressure. Preferably, the duration of the first
lyophilisation phase is
no more than about 60 minutes, more preferably no more than about 30 minutes.
In a second lyophilisation phase, the vacuum pressure and the temperature
within the
chamber are progressively adjusted to reach a target pressure (below
atmospheric pressure) and
a target temperature (below room temperature). The target pressure is
preferably approximately
0.1 mBar. The target temperature is preferably approximately 15 degrees
Celsius. Preferably,
the duration of the second lyophilisation step is between about 24 hours and
about 60 hours.
In a third and final lyophilisation step, the temperature is increased to
approximately room
temperature (22 degrees Celsius) under a full vacuum. Preferably, the duration
of the third
lyophilisation step is between about 24 hours and about 60 hours.
As a further alternative, the drying step of the method of the present
invention may be
carried out using microwave heating. For example, the uncured green tobacco
leaves may be
dried in a microwave tunnel dryer. The use of microwave heating to dry the
uncured green
tobacco leaves advantageously enables the moisture of the leaves to be removed
very quickly
since the microwaves can make the temperature of the leaf rise rapidly,
causing the water
molecules within the tobacco to evaporate.
Preferably, during the drying step, the uncured green tobacco leaves are
continuously
transferred through one or more microwave units, for example, on a conveyor
belt. The power
and duration of the microwave heating step can be adapted in order to provide
the required
moisture level of the tobacco leaves.
Suitable microwave tunnel dryers are commercially available, for example, from
Jinan
Himax machinery Co., Ltd.
After the uncured green tobacco leaves have been dried to the required
moisture content
of between 4 percent and 15 percent by weight, the dried tobacco leaves are
processed in order
to form dried green tobacco material of the desired size. The uncured green
tobacco leaves are
preferably cut or ground using known techniques for producing tobacco
particles.
Specific embodiments will be further described, by way of example only, with
reference to
the accompanying drawings in which:
Figure 1 illustrates a first embodiment of a substrate of an aerosol-
generating article as
described herein;
Figure 2 illustrates an aerosol-generating system comprising an aerosol-
generating article
and an aerosol-generating device comprising an electric heating element;
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-40-
Figure 3 illustrates an aerosol-generating system comprising an aerosol-
generating article
and an aerosol-generating device comprising a combustible heating element;
Figure 4 is a cross sectional view of filter 1050 further comprising an
aerosol-modifying
element, wherein
Figure 4a illustrates the aerosol-modifying element in the form of a spherical
capsule or bead within a filter plug.
Figure 4b illustrates the aerosol-modifying element in the form of a thread
within
a filter plug.
Figure 4c illustrates the aerosol-modifying element in the form of a spherical
capsule within a cavity within the filter; and
Figure 5 is a cross sectional view of a plug of aerosol-generating substrate
1020
further comprising an elongate susceptor element.
Figure 1 illustrates a heated aerosol-generating article 1000 comprising a
substrate as
described herein. The article 1000 comprises four elements; the aerosol-
generating substrate
1020, a hollow cellulose acetate tube 1030, a spacer element 1040, and a
mouthpiece filter 1050.
These four elements are arranged sequentially and in coaxial alignment and are
assembled by a
cigarette paper 1060 to form the aerosol-generating article 1000. The article
1000 has a mouth-
end 1012, which a user inserts into his or her mouth during use, and a distal
end 1013 located at
the opposite end of the article to the mouth end 1012. The embodiment of an
aerosol-generating
article illustrated in Figure 1 is particularly suitable for use with an
electrically-operated aerosol-
generating device comprising a heater for heating the aerosol-generating
substrate.
When assembled, the article 1000 is about 45 millimetres in length and has an
outer
diameter of about 7.2 millimetres and an inner diameter of about 6.9
millimetres.
The aerosol-generating substrate 1020 comprises a plug formed from a sheet of
homogenised tobacco material comprising a blend of dried green tobacco
material with cured
tobacco particles.
A number of examples of a suitable homogenised tobacco material for forming
the aerosol-
generating substrate 1020 are shown in Table 1 below (see Samples A and B).
The sheet is
gathered, crimped and wrapped in a filter paper (not shown) to form the plug.
The sheet includes
additives, including glycerol as an aerosol former.
An aerosol-generating article 1000 as illustrated in Figure 1 is designed to
engage with an
aerosol-generating device in order to be consumed. Such an aerosol-generating
device includes
means for heating the aerosol-generating substrate 1020 to a sufficient
temperature to form an
aerosol. Typically, the aerosol-generating device may comprise a heating
element that surrounds
the aerosol-generating article 1000 adjacent to the aerosol-generating
substrate 1020, or a
heating element that is inserted into the aerosol-generating substrate 1020.
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-41-
Once engaged with an aerosol-generating device, a user draws on the mouth-end
1012
of the smoking article 1000 and the aerosol-generating substrate 1020 is
heated to a temperature
of about 375 degrees Celsius. At this temperature, volatile compounds are
evolved from the
aerosol-generating substrate 1020. These compounds condense to form an
aerosol. The aerosol
is drawn through the filter 1050 and into the user's mouth.
Figure 2 illustrates a portion of an electrically-operated aerosol-generating
system 2000
that utilises a heating blade 2100 to heat an aerosol-generating substrate
1020 of an aerosol-
generating article 1000. The heating blade is mounted within an aerosol
article receiving chamber
of an electrically-operated aerosol-generating device 2010. The aerosol-
generating device
defines a plurality of air holes 2050 for allowing air to flow to the aerosol-
generating article 1000.
Air flow is indicated by arrows on Figure 2. The aerosol-generating device
comprises a power
supply and electronics, which are not illustrated in Figure 2. The aerosol-
generating article 1000
of Figure 2 is as described in relation to Figure 1.
In an alternative configuration shown in Figure 3, the aerosol-generating
system is shown
with a combustible heating element. While the article 1000 of Figure 1 is
intended to be consumed
in conjunction with an aerosol-generating device, the article 1001 of Figure 3
comprises a
combustible heat source 1080 that may be ignited and transfer heat to the
aerosol-generating
substrate 1020 to form an inhalable aerosol. The combustible heat source 80 is
a charcoal
element that is assembled in proximity to the aerosol-generating substrate at
a distal end 13 of
the rod 11. Elements that are essentially the same as elements in Figure 1
have been given the
same numbering.
Figure 4 is a cross sectional view of filter 1 050 further comprising an
aerosol-modifying
element. In Figure 4a, the filter 1050 further comprises an aerosol-modifying
element in the form
of a spherical capsule or bead 605.
In the embodiment of Figure 4a, the capsule or bead 605 is embedded in the
filter segment
601 and is surrounded on all sides by the filter material 603. In this
embodiment, the capsule
comprises an outer shell and an inner core, and the inner core contains a
liquid flavourant. The
liquid flavourant is for flavouring aerosol during use of the aerosol-
generating article provided with
the filter. The capsule 605 releases at least a portion of the liquid
flavourant when the filter is
subjected to external force, for example by squeezing by a consumer. In the
embodiment shown,
the capsule is generally spherical, with a substantially continuous outer
shell containing the liquid
flavou rant.
In the embodiment of Figure 4b, the filter segment 601 comprises a plug of
filter material
603 and a central flavour-bearing thread 607 that extends axially through the
plug of filter material
603 parallel to the longitudinal axis of the filter 1050. The central flavour-
bearing thread 607 is of
substantially the same length as the plug of filter material 603, so that the
ends of the central
flavour-bearing thread 607 are visible at the ends of the filter segment 601.
In Figure 4b, filter
RECTIFIED SHEET (RULE 91) ISA/EP
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-42-
material 603 is cellulose acetate tow. The central flavour-bearing thread 607
is formed from
twisted filter plug wrap and loaded with an aerosol-modifying agent.
In the embodiment of Figure 4c, the filter segment 601 comprises more than one
plug of
filter material 603, 603'. Preferably, the plugs of filter material 603, 603'
are formed from cellulose
acetate, such that they are able to filter the aerosol provided by the aerosol
generating article. A
wrapper 609 is wrapped around and connects filter plugs 603, 603'. Inside a
cavity 611 is a
capsule 605 comprising an outer shell and an inner core, and the inner core
contains a liquid
flavou rant. The capsule is otherwise similar to the embodiment of Figure 4a.
Figure 5 is a cross sectional view of aerosol-generating substrate 1020
further comprising
an elongate susceptor strip 705. The aerosol-generating substrate 1020
comprises a plug 703
formed from a sheet of homogenised tobacco material comprising a blend of
dried green tobacco
material and cured tobacco particles. The elongate susceptor strip 705 is
embedded within the
plug 703 and extends in a longitudinal direction between the upstream and
downstream ends of
the plug 703. During use, the elongate susceptor strip 705 heats the
homogenised tobacco
material by means of induction heating, as described above.
Exam pie
Different samples of homogenised tobacco material for use in an aerosol-
generating
substrate according to the invention, as described above with reference to the
figures, may be
prepared from aqueous slurries having compositions shown in Table 1. Samples A
to D comprise
dried green tobacco material (either alone or in combination with cured
tobacco particles), in
accordance with the invention. Sample E comprises only cured tobacco particles
and is included
for the purposes of comparison only.
Sample A is formed with a CMC binder in combination with cellulose fibres, in
accordance
with the second preferred embodiment of the invention. Sample A is prepared
from an aqueous
slurry containing 72.97 kg of water per 100 kg of slurry, with the remainder
accounted for by the
components in the relative amounts shown in Table 1.
Samples B to D are formed with a guar gum binder, in accordance with the first
preferred
embodiment of the invention. Samples B to D are prepared from an aqueous
slurry containing
between 78-79kg of water per 100 kg of slurry.
In the table below, % DWB refers to the "dry weight base," in this case, the
percent by
weight calculated relative to the dry weight of the homogenised plant
material. The tobacco
particles have been ground to an average particles size of 100 microns by
triple impact milling.
The dried green tobacco material are derived from Burley tobacco leaves and
have been
fast dried using a heating method according to the present invention, as
described above. The
cured tobacco particles may be derived from one or more types of cured
tobacco, as desired.
RECTIFIED SHEET (RULE 91) ISA/EP
CA 03196772 2023- 4- 26
WO 2022/090497 PCT/EP2021/080181
-43-
The slurries may be casted using a casting bar (0.6 mm) on a glass plate,
dried in an oven
at 140 degrees Celsius for 7 minutes, and then dried in a second oven at 120
degrees Celsius
for 30 seconds.
Table 1. Dry content of slurries
Uncured
Cured
Cellulose
green Glycerol Guar Gum CMC
Sample tobacco
fibres
tobacco (% DWB) (')/0 DWB) (cY0 DWB)
(% DWB)
( /0 DWB)
(4)/0 DWB)
A 25 50 16.7 0 4.6
3.7
75 0 18 3 0 4
37.5 37.5 18 3 0 4
25 50 18 3 0 4
0 75 18 3 0 4
For each of the samples A to E of homogenised tobacco material, a plug may be
produced
from a single continuous sheet of the homogenised tobacco material, the sheets
each having
widths of between 100 mm to 130 mm. The individual sheets preferably have a
thickness of about
220 microns and a grammage of about 189 g/m2. The cut width of each sheet is
about 120 mm.
The sheets may be crimped to a height of 165 microns to 170 microns, and
rolled into plugs
having a length of about 12 mm and diameters of about 7 mm, circumscribed by a
paper wrapper.
The total weight of each plug is about 250 mg.
For each of the plugs, an aerosol-generating article having an overall length
of about 45
mm may be formed having a structure as shown in Figure 3 comprising, from the
downstream
end: a mouth end cellulose acetate filter (about 7 mm long), an aerosol spacer
comprising a
crimped sheet of polylactic acid polymer (about 18 mm long), a hollow acetate
tube (about 8 mm
long) and the plug of aerosol-generating substrate.
Comparative Example 1 ¨ Burley tobacco
In order to demonstrate the effect of the curing process on the chemical
composition of
Burley tobacco, the level of certain tobacco constituents was measured for
three samples of
Burley tobacco leaf: uncured green Burley tobacco leaf, 5 days air-cured
Burley tobacco leaf and
fully air-cured (50 days) Burley tobacco leaf. Each sample starts from the
same uncured green
Burley tobacco leaf and therefore the change in the level of each constituent
is assumed to be a
direct result of the curing process. The results are shown below in Table 2:
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-44-
Table 2: Chemical composition of uncured and cured Burley tobacco leaf (dry
weight
basis)
Tobacco Amount in uncured Amount in 5 days Amount in
fully
constituent green tobacco leaf cured tobacco leaf
cured tobacco leaf
(per gram) (per gram) (per
gram)
Chlorophyll 1.2 mg 0.2 mg 0.2 mg
Asparagine 0.28 mg 12.5 mg 18.4 mg
Ammonia 0.11 mg 0.26 mg 2.55 mg
Total free amino acids 9.69 mg 56.8 mg 48.2 mg
NNN 259.2 ng 1553.6 ng 2154.2 ng
As shown by the table, the level of chlorophyll drops significantly to a very
low level after
only 5 days curing. This demonstrates that the presence of a level of
chlorophyll above 0.5 mg/g
is a good indicator for uncured green tobacco leaves.
The levels of asparagine, ammonia, total free amino acids and NNN were found
to
increase significantly as a result of the curing process so that in each case,
the level of the
constituent in the cured leaf was several times higher than in the uncured
green leaf. As shown
1.0 below, the reduced levels of these constituents in the uncured green
tobacco leaf provided a
reduction in the related undesirable constituent in the aerosol generated from
a homogenised
tobacco material comprising the uncured green tobacco.
The level of sugar in the Burley tobacco leaves was found to vary from 6.87
percent by
weight for the uncured green tobacco leaves to 6.47 percent by weight for the
5 days cured
tobacco leaves and 1.7 percent by weight for the fully cured tobacco leaves,
measured on a dry
weight basis.
For each of the Burley samples, a homogenised tobacco material was formed
using a
casting process as described above and having the composition shown below in
Table 3:
Table 3: Homogenised tobacco material composition:
Component % (dry weight basis)
Burley tobacco particles 37.5
Virginia flue-cured tobacco particles 37.5
Glycerol 18
Guar Gum 3
Cellulose fibres 4
Each of the samples of homogenised tobacco material was gathered to form a rod
of
aerosol-generating substrate having a weight of 250mg which was then
incorporated into an
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-45-
aerosol-generating article as described above in the example. For each of
these aerosol-
generating articles, a mainstream aerosol was generated and collected in
accordance with Test
Method A, as described above. For each sample, the aerosol was trapped and
analysed.
As described in detail above, according to Test Method A, the aerosol-
generating articles
may be tested using the commercially available 1Q0S8 heat-not-burn device
tobacco heating
system 2.2 holder (THS2.2 holder) from Philip Morris Products SA. The aerosol-
generating
articles are heated under a Health Canada machine-smoking regimen over 30
puffs with a puff
volume of 55 ml, puff duration of 2 seconds and a puff interval of 30 seconds
(as described in
ISO/TR 19478-1:2014). The aerosol generated during the smoking test is
collected on a
Cambridge filter pad and extracted with a liquid solvent.
Table 4 below shows the levels of certain tobacco-derived aerosol constituents
in the
aerosols generated from the three samples containing uncured green Burley
tobacco particles, 5
days cured Burley tobacco particles and fully cured Burley tobacco particles.
The amounts of
each aerosol constituent are expressed per article, based on a 250 mg rod of
the aerosol-
generating substrate:
Table 4: Composition of aerosol ¨ amounts of tobacco-derived aerosol
constituents
Uncured green 5 days cured Fully
cured tobacco
Aerosol constituent tobacco leaf tobacco leaf leaf
(per article) (per article) (per
article)
Acrylamide 0.76 g 1.79 lig 2.98 g
Ammonia 6.99 mg 11.15 mg 22.13 mg
Hydrogen sulphide 1.51 g 1.61 g 22.60 p.g
Methanethiol 26.14 pg 31.06 lag 31.25 p.g
Nicotine 1.04 mg 1.02 mg 1.01 mg
The results shown in Table 4 demonstrate the effect of including a proportion
of dried
green tobacco material in the homogenised tobacco material forming the aerosol-
generating
substrate, on the levels of aerosol constituents. Notably, the level of
acrylamide in the aerosol
generated from the sample with dried green tobacco material included was
significantly lower
than for the other two samples using only cured tobacco particles. This is
thought to be due to
the reduced level of asparagine in the uncured tobacco leaf, as described
above. The levels of
ammonia, hydrogen sulphide and methanethiol in the aerosol generated from the
sample with
dried green tobacco material included were also significantly lower than for
the other two samples
using only cured tobacco particles.
The results demonstrate that advantageously, the curing process does not
materially
affect the nicotine released from the tobacco material into the aerosol and so
the use of dried
CA 03196772 2023- 4- 26
WO 2022/090497
PCT/EP2021/080181
-46-
green tobacco material in place of cured tobacco particles does not impact the
nicotine content
of the aerosol.
Overall, the aerosol generated from the sample containing dried green tobacco
material
therefore showed improved levels of certain undesirable compounds whilst
retaining a consistent
nicotine delivery.
Similar reductions in these aerosol constituents would also be expected from
other
tobacco types, such as Virginia.
CA 03196772 2023- 4- 26
