Note: Descriptions are shown in the official language in which they were submitted.
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Pasteurization of Packaged Tobacco
The present invention relates to a method for the pasteurization of tobacco,
in particular fine-
cut tobacco, which comprises heating the tobacco such that the tobacco is
pasteurized.
Roll-your-own and make-your-own tobacco products have a relatively high
moisture content
of typically above 18 weight percent. In comparison, pre-manufactured
cigarettes typically have
moisture content below about 14 weight percent. The high moisture content in
roll-your-own and
make-your-own tobacco facilitates, for example, the handling by the consumer
when making
cigarettes. As tobacco is an organic product, it may be subject to
deterioration by
microorganisms, such as mold. In moderate climates, mold spores are naturally
present
everywhere and the mold growth is favored by moisture. One way to reduce or
prevent mold
growth is the use of preservatives. However, the use of preservatives in
tobacco products may
be disfavored.
It is known in the art to pasteurize snuff, a moist tobacco product with even
higher moisture
content than roll-your-own and make-your-own tobacco, by bulk heating it in a
cooker to
elevated temperatures over a certain period of time. The pasteurized snuff is
then removed from
the cooker and further processed. US 2008/0156338 Al discloses the
pasteurization of snuff,
which has a high moisture content, and, thus, may otherwise have a short shelf
life.
It is the object of the present invention, to provide an improved method for
the pasteurization
of tobacco which provides a constant product quality and a long shelf life.
According to the invention there is provided a method for the pasteurization
of fine-cut
tobacco, in particular laminar tobacco, with a cut width of 0.5 mm to 0.9 mm
(millimeters)
comprising the steps of arranging the tobacco in a closed package, and heating
the tobacco in
the package such that the tobacco is pasteurized. The pasteurization treatment
will reduce the
number of viable microorganisms in the package and prolong product shelf life.
During the
pasteurization the mold count within the tobacco package is significantly
reduced. According to
the invention, the pasteurization treatment is performed on the packaged
product. This is
advantageous in that the moisture level can be maintained at a relatively high
level, and that the
shelf life is significantly increased as compared to non-pasteurized product.
The fine-cut tobacco
comprises strips of tobacco cut from tobacco leaves or reconstituted tobacco
sheets or both, at a
predefined cut width in the range of about 0.5 mm to about 0.9 mm.
The cut width is particularly important for roll-your-own self-manufacture of
smoking articles,
in particular cigarettes, which requires strips or strands of tobacco in a
certain size in order to
prevent the tobacco from falling out at the open end of the smoking article.
Preferably, the strips
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or strands of tobacco are in a predefined moisture range, which makes them
less brittle and
facilitates rolling the tobacco into a tobacco rod during the rolling process
by the consumer.
In contrast, for chewing tobacco, namely snus, the tobacco is mostly ground or
sometimes
finely cut. However, this always results into a sort of dust that then creates
the typical snus pulp
that is filled in the sachets for consumption.
Similarly, snuff is provided as a ground or finely cut powder. US 2008/0156338
Al discloses
that dry snuff is usually provided as a powder, while moist snuff is usually
finely cut.
Nevertheless, snuff or snus is not provided in cut widths as defined above, as
these cut widths
would be detrimental to the intended handling and consumption.
Further reducing the tobacco into such fine dust or pulp has a significant
effect on the
tobacco, for example, on its cell structure or release of essential oils, as
compared to a more
macroscopic cutting of leaves into parallel stripes of a distinctive width.
In particular, fine-cut tobacco is unfermented or free of salt or both, and
preferably not
otherwise treated as snus or snuff is. In some embodiments, fine-cut tobacco
only constitutes of
tobacco leafs cut into stripes. The lack of other ingredients, such as
preservatives, is one of the
main reasons why pasteurization is beneficial. Further, the cut width of the
fine-cut tobacco as
specified is important regarding the combustion process and the resistance-to-
draw during
consumption of the cigarette.
Advantageously, the package used in the present invention is a retail package
and suitable
for product distribution and sale. As the method according to the invention
eliminates the need
for further processing or handling the tobacco after the pasteurization step,
the tobacco is well
protected from environmental factors which could adversely impact the quality
of the tobacco
before use, for example, the ingress of microorganisms. Advantageously, the
package is
substantially air-tight before use. Further, the moisture level of the tobacco
remains substantially
constant between packaging and use.
Advantageously, the pasteurization method according to the invention involves
the heating of
the tobacco in a closed package for a certain period of time to reduce the
mold count by a factor
of at least about 1000 per gram of tobacco, preferably of at least about
100'000 per gram of
tobacco.
In one embodiment, the fine-cut tobacco is pasteurized in a continuous
process, comprising
the steps of: arranging the packages on a continuous conveyor, and applying
heat to the
packages on the conveyor such that all of the tobacco is pasteurized.
Preferably, the heat is
uniformly applied to the packages such that the fine-cut tobacco is uniformly
pasteurized.
Preferably, the moisture level of the tobacco is above 16 weight percent and
preferably below
20 weight percent, more preferably in between 18 and 19 weight percent. In
other embodiments,
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the moisture level is above 18 weight percent and preferably below 35 weight
percent. Tobacco
for roll-your-own and make-your-own applications requires a relatively high
moisture level such
that the tobacco is sufficiently flexible to facilitate manual cigarette
making. The desired tobacco
moisture level is typically set during tobacco processing comprising the
addition of water and
drying.
Preferably, during the heating step, the tobacco is heated between about 55 to
120 degrees
Celsius, preferably between about 60 to about 85 degrees Celsius. Thus, in
this temperature
range an efficient pasteurization can be carried out, and the mold count can
be significantly
reduced.
Preferably, the heating is carried out for between about 30 seconds to about
30 minutes,
more preferably for between about 2 minutes and about 7 minutes. The heating
can usually be
carried out for short period of time, if the heating temperature is high.
However, pasteurization at
a low temperature for a longer time may be beneficial for the quality of the
tobacco and may
pose less requirements on the heat stability of the package. The
pasteurization conditions are
selected such that deterioration of the packaging is prevented while achieving
adequate
pasteurization of the entire content of the package. It has been found, that
the pasteurization
method according to the invention does not adversely affect the quality of the
tobacco product.
Preferably, the heating is carried out by subjecting the package to a heating
medium, in
particular water, steam, air or an inert gas. The heating medium may be a
mixture of water
micro-droplets and saturated steam. Alternatively, the heating medium may be a
mixture of
water, superheated steam and air. Further, the heating medium may be a mixture
of water,
steam and air. Generally, the heating medium may be a hot liquid or a hot
liquid vapour.
Depending on the heat capacity of the heating medium, the amount of heat
transferred to the
package and the tobacco therein can be controlled. In particular, it is
preferable, if a current is
provided in the heat medium, such that the heat medium passes the package in
order to prevent
the formation of locally reduced temperatures around the package.
Advantageously, a package
according to the invention may be further overwrapped by a water proof outer
wrapper to
prevent damage to the package that could be otherwise caused by the heating
medium, such as
water. This is particularly advantageous where the package comprises print or
cardboard or
both.
In a preferred embodiment, the tobacco is heated by means of microwave
radiation. This is in
particular beneficial, as the tobacco comprises a significant moisture level,
such that the
microwave radiation will be able to quickly heat up the tobacco. Thus, a
heating by means of
microwave radiation allows reducing the time necessary for the heating step.
The applied
microwave power is preferably controlled to achieve uniform heating and
pasteurization of the
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tobacco by temperature measurement and control of microwave generator power
during
continuous processing of the tobacco packages. The applied microwave power may
be
controlled to achieve uniform heating and pasteurization of the tobacco by
control of microwave
generator power for successive microwave heating steps, taking into account
the specific
product parameters of the tobacco being treated, such as water content, which
are predefined or
determined by according sensors. In one embodiment, the applied microwave
power is
controlled based on measurements of the temperature inside the closed package,
to prevent the
creation of hot or cold spots during pasteurization. The microwave heating
power may be
applied in at least two heating stages, taking into account the specific
product parameters, such
as water content, which are predefined or determined by according sensors, of
the tobacco
being treated, to prevent the creation of hot or cold spots during treatment.
In one embodiment, the heating is carried out at a pressure above atmospheric
pressure. At
a higher pressure, the package may be compressed, such that there is less
space in between
the individual tobacco particles. Thus, heat conduction in the package can
occur faster. In such
a preferred embodiment of the method according to the invention, the heating
of the tobacco can
be carried out more homogenous and quicker. In another embodiment, the
pasteurization of the
tobacco is carried out at atmospheric pressure. In further embodiments, the
pasteurization of the
tobacco is carried out at a pressure below atmospheric pressure, to allow
treatment with specific
pasteurization fluids, such as water, at temperatures of less than 100 degrees
Celsius. The
pressure during pasteurization is preferably controlled in dependency of the
temperature of the
treatment and the heating medium outside the package or pasteurization medium
inside the
package used.
In particular, after the heating, a cooling step may be carried out by
subjecting the package to
a cooling medium, in particular cold air, water or inert gas. Again, the heat
capacity of the
cooling medium allows adjusting the time necessary for the cooling step.
Further, a current in the
cooling medium such as generated by a pump or by a fan may be beneficial. The
cooling of the
tobacco may beneficially be effected by spraying a mist of cool water onto the
package. The
evaporation of small water droplets in the mist improves the cooling
properties.
Gaseous cooling or heating media are preferred over liquid heating media.
While gaseous
cooling or heating media comprise a lower heat capacity than liquid cooling
media, they however
have fewer requirements regarding the material of the package, and do not
require the package
to dry after the heating or cooling step. As the package is closed, preferably
in a hermetic or
gas-tight manner, usually the cooling or heating media cannot interfere with
the tobacco.
In one embodiment, the cooling is effected to a temperature of the tobacco
which is lower
than ambient temperature. This allows, that the tobacco can be maintained at
the lower
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temperature level, which allows keeping the tobacco fresh, and, thus, a longer
storage and shelf
life for the closed package as retail product. It is emphasized, that after
the cooling, the package
comprising the tobacco may be distributed while being chilled, in particular
transported in a
chilled state. Further, chilled storage of the tobacco after or before
transportation may be applied
and is beneficial regarding the shelf life as well.
Preferably, the temperature of the tobacco is monitored during the heating
step. This can be
obtained by monitoring the temperature around the package, and estimating from
this
temperature the temperature of the tobacco. Furthermore, the temperature of
the tobacco may
be measured by infrared sensors. The monitoring of the temperature allows as
well controlling of
the temperature during the heating step. Thus, by implementing an analog or
digital control
device, which controls the amount of energy provided to the closed package
comprising the
tobacco, defined conditions during the pasteurization can be obtained.
In an embodiment, the temperature of the fine-cut tobacco may be measured at
the start and
at the end of a heating step, and the applied heating power for a subsequent
heating step is
adjusted to achieve a uniform, desired temperature of the tobacco.
Preferably, the temperature in the centre of packaged tobacco in the package,
which is
suitable for product sale to the consumer, is measured at the start and at the
end of a heating
step, and the applied heating power for a subsequent heating step is adjusted
to achieve a
uniform, desired temperature of the tobacco throughout the package.
The temperature may also be controlled or monitored during the cooling step.
In one embodiment, the temperature might be changed during the pasteurization
process. In
particular, the heating step may comprise several different heat levels, thus,
the closed package
comprising tobacco is subjected to different temperatures. This can improve
the efficiency of the
pasteurization.
In an embodiment, the packages are passed through a layer of heating medium,
in particular
steam, to enable a continuous pasteurizing of fine-cut tobacco. Further, the
packages may be
conveyed through a counter-flow of heating medium, in particular steam. The
heating medium
may comprise water micro-droplets and steam.
The fine-cut tobacco may be packed in a package suitable for product sale to
consumers.
The microwave power applied to the tobacco packages may be controlled based on
the
temperature measured at the centre of the packages, for example by means of an
infrared
temperature sensor, such as an infrared camera. The position of the tobacco
packages may be
controlled during pasteurization relative to the position of the microwave
heating apertures.
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While it is generally preferred carrying out the pasteurization at the
packaging site, due to a
better control of the pasteurization process, it is alternatively possible,
that the pasteurization
may be performed at the retailer.
According to the invention, further a device for the pasteurization of tobacco
is provided,
comprising a packing station, heating station and optionally a cooling
station, wherein the device
is adapted to conduct the inventive method as specified beforehand.
In particular, the tobacco is filled in packages, such as flexible pouches in
the packing
station, which are then hermetically closed. This may be obtained by heat
sealing the packages.
In the heating station, one or several closed packages comprising tobacco are
subjected to heat,
until the tobacco comprised therein is pasteurized. In the optional cooling
station, the packages
may be brought back to ambient temperature, or the packages may be cooled down
to a
temperature below ambient temperature to prolong the shelf life. In any case,
the cooling station
may provide the benefit of making the method faster, and the cooling time can
be reduced.
The surface temperature of the tobacco in the package is preferably about 55
to 120 degrees
Celsius, more preferably between about 60 to about 85 degrees Celsius.
In one embodiment, the external pressure around the closed package is
controlled during the
pasteurization to prevent bursting of the pack. Further or alternatively, the
package may be
contained within an external enclosure during the treatment to prevent
bursting of the package.
Several packages may be provided together in one external enclosure,
preferably 2 to 10
packages, more preferably 5 to 10 packages.
Preferably, the fine-cut tobacco is pasteurized by heat treating the tobacco
within its
consumer package, wherein the consumer package is sealed within a disposable,
protective
packaging prior to heat treatment, and the disposable, protective packaging is
removed after
heat treatment.
After pasteurization, the tobacco is substantially free of active
microorganisms.
The invention also relates to a packaged tobacco product comprising fine-cut
tobacco with a
cut width of 0.5 mm to 0.9 mm (millimeters), manufactured by the inventive
method as specified
beforehand. In particular, the package of the packaged tobacco product is a
retail pouch or retail
container, in which the tobacco will be sold in stores.
Preferably, the packaged tobacco product is a flexible pouch as known for roll-
your-own
tobacco. However, it is designed to withstand the temperature during the
pasteurization step.
According to the invention, the package can be at least partially evacuated
before pasteurization
by partially removing air or process gas from the package before sealing. This
has the benefit
that the heat transfer between the tobacco and the heating medium can be
improved, as the
insulating air is removed. Preferably the package is made of a laminate which
provides a
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moisture barrier and is impermeable to microorganisms. Further, the package is
preferably
permeable to microwaves.
Preferably, the tobacco in the packaged tobacco product is free from
preservatives.
Generally, additives may be added to tobacco during manufacturing such as
sugar, cocoa,
coconut powder, humectants like for example, glycerin, propylene glycol and
invert sugar and
others. Possible preservatives used in tobacco products may comprise benzoic
acid, sodium
propionate, natamycin, non-anoic acid and salts thereof.
Preferably, the packaging material is plastic, metal or cardboard laminates or
a combination
thereof. Preferably, the package of the packaged tobacco product is made of a
laminate wherein
at least one layer provides a moisture barrier. In other the embodiments, the
package may
provide a moisture barrier, without being made from a laminate material. This
allows, that in
particular during the heating, no moisture will escape the package, such that
the moisture level
in the tobacco will remain constant. Same benefit is also provided during the
latter transport and
while the product is kept on a shelf for storage and sale, as no evaporation
of moisture from the
tobacco to the outside of the package can occur.
The closed package is preferably suitable for product sale to the consumer.
In particular, the packaged tobacco product has a weight of 10g to 500g. This
is a common
range for retail tobacco packages. In particular, pouches with around 30g or
100g and closed
boxes with around 140g of tobacco may be provided as the packaged tobacco
product
according to the invention.
The packaged fine-cut tobacco according to the invention may be used for make-
your-own or
roll-your-own products, wherein it has been pasteurized to provide enhanced
shelf-life and
improved sensory properties. In the following, an exemplary embodiment of the
method, device
and product according to the invention will be explained with reference to the
following figure.
Figure 1 shows an exemplary manufacturing line for the method according to the
invention.
The present invention relates to a method for pasteurization of tobacco, in
particular fine-cut
tobacco for roll-your-own and make-your-own products.
Generally, in the first stage tobacco leaves or tobacco leaf pieces will be
processed in a
common manner, including conditioning, sorting and separation of unwanted
material. Then, the
leaves or leaf pieces are cut into fine cut tobacco with a cut width of 0.5 to
0.9 mm, and water
and additional ingredients such as additives are added. Finally, the tobacco
is dried to a certain
moisture level, in particular more than 18 weight percent.
The accordingly processed tobacco is indicated with reference number 1 in
Figure 1.
The tobacco 1 is then filled in a package 2 in a packing station 3. The
packing station 3
further provides that the package 2 is closed, such that it is hermetically
sealed. In particular, the
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package 2 is a flexible pouch, which will be heat sealed to be closed.
However, the closure of
the package 2 can be designed such that is openable by a consumer, without the
pouch being
destroyed. In particular the package 2 is adapted to be reclosable.
Alternatively or additionally to
closing the package by heat sealing, the package 2 may be provided with
adhesive to be closed
such that it is hermetically sealed. In some embodiments the package 2 may be
heat sealed on
some of the sides, while a reclosable opening is only provided with adhesive.
The adhesive
provided on the opening of the package 2 is in particular non-permanent
adhesive allowing as
well to reclose the package substantially airtight.
From the packing station 3, the closed packages 2 are transported by a
conveyance means
4, for example a conveyance belt, to the heating station 5. In the heating
station 5 the packages
2 are heated such that the tobacco 1 comprised therein is pasteurized. In
particular, the
packages 2 will be heated to 60-85 degrees Celsius for 2 to 7 minutes. The
heating is carried out
by using a heat medium, which is in the present embodiment hot air. The
heating station 5 may
be an oven with a hot air fan. A conveyance means extends through the heating
station 5.
It is emphasized that in some embodiments it is beneficial to heat the
packages 2 individually
in the heating station. In other embodiments, a plurality of packages 2 is
heated together in the
heating station. However, the plurality of the packages 2 is preferably
arranged in a manner that
the same heating conditions are provided for each of the packages 2, such that
a constant
quality product is obtained.
In some embodiments, the closed package 2 may be provided in an additional
external
enclosure. The external enclosure remains around the package at least during
the heating step.
In particular, the enclosure protects the package from the heating medium and
the direct
application of heat. The external enclosure is preferably substantially fluid-
tight. In particular the
external enclosure may be formed from a film material to enable that it may
adapt to the outer
form of the closed package 2. The external enclosure may be reclosable to
enable reusing of
same several times. The external enclosure enclosing the packages may be
evacuated before
the heat treatment to ensure that it is directly in contact with the packages
to improve the heat
transfer to the packages. In one embodiment, several packages may be provided
in one external
enclosure together, preferably 2 to 10 packages, more preferably 5 to 10
packages.
It is important that the tobacco 1 in the core of the package 2 reaches the
required target
temperature, such that all tobacco 1 in the package 2 is pasteurized. As the
package 2 is sealed
and is made of moisture proof material, the moisture comprised in the tobacco
cannot escape
the package 2, and is, thus, held at a constant level.
During the heating step, the temperature of the tobacco 1 is preferably
monitored, either
directly or indirectly by monitoring the temperature of the package 2. The
heat that needs to be
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applied will depend on the type and size of the package 2, while the
temperature of the tobacco
1 is used as an indication of the pasteurization process.
Thus, the presence of microorganisms such as mould is reduced in the tobacco
1, and the
tobacco 1 in the packages 2 has a longer shelf life.
The packages 2 either are stopped during the heating step, or they move
continuously on a
conveyance means through the heating station 5. In some embodiments, the
package 2 may be
subjected to pressure in the heating station 5, such that the gas or air
comprised in the package
2 is compressed, and the tobacco 1 is closer to the package wall and can thus
be heated
quicker.
In some embodiments, a microwave is used as a heating means for heating the
tobacco in
the package 2.
The package 2 may in particular be made of a laminate, wherein one layer of
the laminate
forms a moisture barrier.
After the heating in the heating station 5, the closed packages 2 are further
transported to a
cooling station 6, in which a cooling step is carried out. A conveyance means
extends through
the cooling station 6. The cooling step is not necessary in all embodiments
and could be
replaced by keeping the product at ambient conditions after the heating step.
For the cooling
step, ambient or cold air is used, to cool the product down to ambient
temperature or to a
temperature below ambient temperature. In particular, the package 2 is cooled
down to 2 to 10
degrees Celsius, and is subsequently kept at this temperature during further
transport until it
reaches the point of sale such that the shelf life is increased.
Typical shelf life for tobacco treated with the aforementioned method is 6
months.
