PASTEURISATION OF FINE CUT TOBACCO

Abstract

There is provided a method of making a product containing pasteurised fme cut tobacco for combustible use. The method comprises arranging fme cut tobacco (1) comprising elongate strips of tobacco having a cut width of less than 0.5 mm and a moisture content of at least 18 percent by weight, and heating the fme cut tobacco (1) such that the tobacco is pasteurised. Further, there is provided a product containing pasteurised fme cut tobacco (1) for combustible use. The product comprises a closed package (2); and pasteurised fme cut tobacco (1) within the closed package (2), the pasteurised fme cut tobacco (1) having a cut width of less than 0.5 mm and a moisture content of at least 18 percent by weight, and a colony forming unit (CFU) value of less than 2 log lo colony forming units per gram.

Claims

1. A method of making a product containing pasteurised fine cut tobacco for combustible use, the method comprising: arranging fine cut tobacco comprising elongate strips of tobacco having a cut width of less than 0.5 mm and a moisture content of at least 18 percent by weight, and heating the fine cut tobacco such that the tobacco is pasteurised.

2. A method according to claim 1, wherein the fine cut tobacco has a moisture content of between 20 and 25 percent by weight.

3. A method according to claim 12, wherein the fine cut tobacco has a moisture content of between 20 and 23 percent by weight.

4. A method according to claim 1, wherein the fine cut tobacco has a water activity level of between 0.7 Aw and 0.8 Aw after the fine cut tobacco has been pasteurised.

5. A method according to claim 1, wherein during the heating step, the fine cut tobacco is heated to a pasteurisation temperature of between 75 and 95 degrees Celsius.

6. A method according to claim 5, wherein during the heating step, the fine cut tobacco is heated to a pasteurisation temperature of between 80 and 90 degrees Celsius.

7. A method according to claim 1, wherein the heating step is carried out such that the fine cut tobacco is heated at a pasteurisation temperature for a duration of between 3 and 7 minutes.

8. A method according to claim 1, wherein the fine cut tobacco comprises between 5 and 25 percent by dry weight of reducing sugars.

9. A method according to claim 1, wherein the arranging step further comprises arranging the fine cut tobacco in a package, and the heating step further comprises heating the fine cut tobacco in the package.

10. A method according to claim 1, wherein the fine cut tobacco has a cut width of between 0.2 mm and 0.4 mm.

11. A method according to claim 1, wherein the fine cut tobacco has a filling power of less than 5 cubic centimetres/g.

12. A product containing pasteurised fine cut tobacco for combustible use, the product comprising: a closed package; and pasteurised fine cut tobacco comprising elongate strips of tobacco within the closed package, the pasteurised fine cut tobacco having a cut width of less than 0.5 mm and a moisture content of at least 18 percent by weight, and a colony forming unit (CFU) value of less than 2 logio colony forming units per gram.

13. A product according to claim 12, wherein the fine cut tobacco has a water activity level of between 0.7 Aw and 0.8 Aw.

14. A product according to claim 12, wherein the fine cut tobacco comprises between 5 and 25 percent by dry weight of reducing sugars.

15. A product according to claim 10, wherein the pasteurised fine cut tobacco is sealed in the closed package.

16. A product according to claim 10, wherein the closed package is a pouch comprising a pocket that contains the fine cut tobacco and a flap configured to fold over the pocket, or wherein the closed package is a stand up bag formed of flexible material, and the bag comprises a base and at least two side walls, or wherein the closed package is rigid tin or container.

Description

[0047] Preferred embodiments of the invention in its various aspects will now be described by way of non-limiting example with reference to the attached figures, in which

[0048] FIG. 1 shows an exemplary manufacturing line for the method according to the invention; and

[0049] FIG. 2 shows a Graph representing plots of mould levels over a 6 month storage period.

[0050] 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.

[0051] 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 less than 0.5 mm, and water and additional ingredients such as additives are optionally added. Finally, the tobacco is dried to a certain moisture content, in particular more than 18 weight percent.

[0052] The accordingly processed tobacco is indicated with reference number 1 in FIG. 1.

[0053] In accordance with this embodiment, the tobacco 1 is then filled in a package 2 in a packing station 3. However, the tobacco may instead be pasteurised in bulk, for example by conveying unpackaged tobacco through a heating station for pasteurisation, and then subsequently packaging the tobacco after the heating station.

[0054] As shown in FIG. 1, the packing station 3 further provides that the package 2 is closed, such that it is hermetically sealed. In particular, the 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.

[0055] 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 therein is pasteurized. In particular, the packages 2 will be heated until the fine cut tobacco reaches a pasteurisation temperature of between 75 to 95 degrees Celsius. Once the packages are at such a pasteurisation temperature, the packages are then subjected to this temperature for a duration of 2 to 7 minutes. Sensors may be provided for determining when the packages are at the pasteurisation temperature. The heating is carried out by using a heat medium, which in the present embodiment is hot air. The heating station 5 may be an oven with a hot air fan. A conveyance means extends through the heating station 5. The air may be filter or purified before the pasteurised tobacco is subjected to it as a heating medium.

[0056] 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 in the tobacco cannot escape the package 2, and is, thus, held at a constant level.

[0057] 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 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.

[0058] Thus, the presence of microorganisms such as mould is reduced in the tobacco 1, so that the tobacco 1 in the packages 2 can have a longer shelf life.

[0059] 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. 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.

[0060] Typical shelf life for tobacco treated with the aforementioned method is at least 6 months.

[0061] Various studies were performed to determine the effect of different pasteurisation conditions on different samples of fine cut tobacco. Results from these studies are shown in Table 1, Table 2 and FIG. 2.

[0062] Table 1 shows the cut width, moisture content and added humectant values for five different samples of fine cut tobacco that were subjected to pasteurisation trials. In order to assess the effectiveness of the pasteurisation across a range of initial mould levels, each sample was divided into two sub-categories; inoculated and non-inoculated. The inoculated samples were ones for which the tobacco sample was first inoculated with mould, by a dry rubbing technique where the tobacco was rubbed on the surface of agar plates containing cultured moulds of P. chrysogenum and A. (Eurotium) amstelodami. In order to achieve a desired level of 10.sup.6-10.sup.7 colony forming units/gram 200 mould containing DG-18 plates were used, with approximately 20 grams of tobacco being rubbed on each plate. The rubbed tobacco was then placed into a large bag and shaken to ensure even mixing of the tobacco prior to filling individual pouches of tobacco.

[0063] Each inoculated and non-inoculated sample was then divided into 3 further subcategories for different pasteurisation conditions. These were pasteurisation at 70 degrees Celsius for 5 minutes, pasteurisation at 75 degrees Celsius for 5 minutes and pasteurisation at 85 degrees Celsius for 5 minutes. The reduction in mould level for each category is shown in Table 1 below. The shaded cells indicate the samples for which the mould level was reduced below the limit of detection (approximately <0.5 log colony forming units per gram).

TABLE-US-00001 TABLE 1 Sample Overview and Mould Level Reduction Reduction In Mould Levels (log.sub.10cfu/g) After 5 Tobacco Sample Minutes Treatment at 70, 75 or 85 C. Cut Moisture Added 70 C. 75 C. 85 C. Sample Width Content Humectant Non- Non- Non- No. (mm) (% weight) (% weight) Inoculated Inoculated Inoculated Inoculated Inoculated Inoculated 1 0.3 21.9 5 4.85 0.37 6.32 2.16 6.67 2.04 2 0.5 22.2 5 3.04 0 6.51 2.91 6.47 2.17 3 0.4 21.7 5 5.36 1.33 6.47 2.57 6.95 2.28 4 0.4 22.9 5 5.55 2.77 5.61 2.68 6.67 3.2 5 0.5 21.4 5 2.93 0.25 6.81 2.26 6.85 2.37 6 0.3 23 5 4.11 1.21 6.51 1.8 6.58 1.8 7 0.3 23 0 4.99 1.69 4.84 2.17 6.77 2.66

[0064] Therefore, as can be seen in Table 1, the mould level in all samples with cut widths of greater than or equal to 0.5 mm could be reduced below the limit of detection through pasteurisation at temperatures of 75 degrees Celsius or more. The mould level in samples 3 and 6 (i.e. ones having a cut width of less than 0.5 mm) could also be reduced below the limit of detection through pasteurisation at temperatures of 75 degrees Celsius or more. However, a pasteurisation temperature of greater than 75 degrees Celsius was needed to reduce the mould level in samples 1, 4 and 7 below the limit of detection.

[0065] A shelf life study of the pasteurised samples was then conducted. In particular, after the samples had been subjected to the pasteurisation conditions set out in Table 1, they were then stored at 25 degrees Celsius for a period of at least 6 months and the mould level in each sample was measured at set points throughout the 6 month period. The measured mould level for each inoculated sample is shown in Table 2 below.

TABLE-US-00002 TABLE 2 Shelf Life Analysis of Each Sample Mould Levels (log.sub.10cfu/g) Of Inoculated Samples Throughout 6M Tobacco Sample At Storage At 25 C., After Heating For 5 minutes At 70, 75 or 85 C. Different Temperature 0.1 Month 1 Month 2 Months 4 Months 6 Months 1 (0.3 mm) 70 C. 2.32 3.01 2.23 1.82 1.4 75 C. 0.85 <0.5 <0.5 <0.5 1.08 85 C. <0.5 <0.5 <0.5 <0.5 1.45 2 (0.5 mm) 70 C. 4.33 3.86 3.80 3.3 1.75 75 C. <0.5 <0.5 <0.5 <0.5 0.5 85 C. <0.5 <0.5 <0.5 <0.5 <0.5 3 (0.4 mm) 70 C. 2.14 0.90 0.91 2.71 0.57 75 C. <0.5 <0.5 <0.5 <0.5 <0.5 85 C. <0.5 <0.5 <0.5 <0.5 <0.5 4 (0.4 mm) 70 C. 1.66 3.57 2.1 0.5 1.15 75 C. 1.49 <0.5 1.2 <0.5 0.69 85 C. <0.5 <0.5 <0.5 <0.5 <0.5 5 (0.5 mm) 70 C. 4.12 3.97 2.5 3.54 3.33 75 C. <0.5 1.46 1.12 3.8 2.14 85 C. <0.5 <0.5 <0.5 3.91 2.8 6 (0.3 mm) 70 C. 2.74 1.15 1.72 2.24 2.15 75 C. <0.5 <0.5 <0.5 <0.5 2.47 85 C. <0.5 <0.5 <0.5 <0.5 1.97 7 (0.3 mm) 70 C. 2.18 5.16 2.52 mouldy mouldy 75 C. 2.33 5.78 4.42 mouldy mouldy 85 C. <0.5 1.6 <0.5 <0.5 <0.5

[0066] As can be seen from Table 2, for all samples there were surviving moulds throughout the 6 month shelf life, if the tobacco had been subjected to a pasteurisation temperature of 70 degrees Celsius for 5 minutes. For all samples (except sample 7) there were very low levels or non-detectable levels of moulds throughout the 6 month shelf life, if the tobacco had been subjected to a pasteurisation temperature of 75 degrees Celsius or more for 5 minutes.

[0067] Interestingly, sample 7 behaved differently from the other samples. In particular, the inoculated and non-inoculated categories of sample 7 that were heated for 5 minutes at 70 degrees Celsius or 75 degrees Celsius went mouldy between 2 and 4 months of storage. However, when sample 7 was heated at 85 degrees Celsius for 5 minutes, both its inoculated and non-inoculated versions remained mould free for the full duration of the 6 months storage. Sample 7 was the only sample that did not contain added humectant, meaning it was likely to contain more free water on its surface. Wth a moisture content of at least 18 percent weight (in this case 23 percent by weight), this would be expected to significantly promote mould growth, so it is particularly surprising that pasteurisation at a temperature of 85 degrees Celsius for 5 minutes was sufficient to prevent detectable mould growth on the inoculated version of sample for a duration of at least 6 months. This can be best appreciated from FIG. 2.