Tobacco treatment

Abstract

The invention relates to a method of treating tobacco to reduce or eliminate nitrosamines therefrom. The method comprises the use of a supercritical fluid extraction medium at elevated temperature and pressure to selectively remove nitrosamines compared with nicotine removal. The nitrosamnine content for all tobacco types can be reduced.

1 . A tobacco treatment process wherein tobacco is subjected to treatment with a supercritical fluid extraction medium to extract nitrosamines from said tobacco.  
     
     
         2 . A process according to  claim 1 , whereby said nitrosamines are separated from said supercritical fluid extraction medium by subjecting said extraction medium to a nitrosamine removal process.  
     
     
         3 . A process according to  claim 2 , wherein said nitrosamine removal process comprises a chemisorption step.  
     
     
         4 . A process according to  claim 3 , wherein said chemisorption step comprises the use of an ion exchanger.  
     
     
         5 . A process according to  claim 2 , wherein said nitrosamine removal process comprises an adsorbent step.  
     
     
         6 . A process according to  claim 5 , wherein an adsorbent of said adsorbent step is selected from one or more of the group consisting of glass beads, activated charcoal, aluminium silicate and zeolites.  
     
     
         7 . A process according to  claim 2 , wherein said nitrosamine removal process comprises treatment of said extraction medium with ultraviolet (UV) light.  
     
     
         8 . A process according to  claim 2 , wherein said nitrosamine removal process comprises either precipitation of said nitrosamines from said extraction medium, or subjecting said extraction medium to nitrosamine-specific enzyme breakdown, or chromatographic separation of said nitrosamines from said extraction medium.  
     
     
         9 . A process according to any one of claims  2 - 8 , wherein said nitrosamine removal process comprises a plurality of removal processes.  
     
     
         10 . A process according to any one of claims  2 - 9 , wherein following said nitrosamine removal process, said extraction medium, being wholly or substantially free of said nitrosamines, is brought into contact with the tobacco, such that extract(s) other than nitrosamines in said extraction medium may be incorporated or re-incorporated with said tobacco.  
     
     
         11 . A process according to  claim 10 , wherein said extract(s) comprise nicotine and/or flavour substances.  
     
     
         12 . A process according to any one of the preceding claims wherein said supercritical fluid extraction medium is supercritical carbon dioxide.  
     
     
         13 . A process according to any one of the preceding claims, wherein an acid is added to said tobacco prior to treatment of said tobacco with said supercritical fluid; or to said supercritical fluid prior to treatment of said tobacco with said supercritical fluid.  
     
     
         14 . A process according to any one of claims  4  or  5  when appended to  claim 3 , wherein an acid is added to the ion exchanger or adsorbent.  
     
     
         15 . A process according to any one of claims  1 - 14 , wherein one or more of an organic solvent or an alcohol is added in addition to, or alternatively of, said acid.  
     
     
         16 . A process according to  claim 15 , wherein said acid is an organic acid.  
     
     
         17 . A process according to  claim 16 , wherein said acid is an organic acid selected from one or more of the group consisting of malonic acid, ascorbic acid, succinic acid, glutanic acid, adipic acid, malic acid, tartaric acid, mucic acid and citric acid, or a salt derivative thereof.  
     
     
         18 . A process according to  claim 17 , wherein said organic acid is a citric acid salt.  
     
     
         19 . A process according to  claim 18 , wherein said citric acid salt is potassium citrate.  
     
     
         20 . A process according to any one of the preceding claims, wherein said extraction of said nitrosamines from said tobacco with said supercritical fluid takes place at an elevated pressure and temperature.  
     
     
         21 . A process according to  claim 20 , wherein when supercritical fluid is supercritical carbon dixoide, said pressure is in the range of 100 to 350 bar.  
     
     
         22 . A process according to  claim 21 , wherein said pressure is about 200 to 300 bar.  
     
     
         23 . A process according to  claim 22 , wherein said pressure is about 240 to 260 bar.  
     
     
         24 . A process according to any one of claims  20 - 23 , wherein said temperature is greater than about 35° Celsius.  
     
     
         25 . A process according to  claim 24 , wherein said temperature is an a range of about 35° to about 140+ Celsius.  
     
     
         26 . A process according to  claim 25 , wherein said temperature is in a range of about 35° to about 90° Celsius.  
     
     
         27 . A process according to any one of the preceding claims, wherein said tobacco is placed in a closable chamber or bomb during said extraction treatment thereof with supercritical fluid.  
     
     
         28 . A process according to any one of  claims 20  to  27 , wherein said elevated temperature is effected by heat transfer or by electromagnetic radiation.  
     
     
         29 . A process according to any one of the preceding claims wherein no, or very little, nicotine is removed from said tobacco in said extraction medium.  
     
     
         30 . A process according to any one of the preceding claims, wherein the pH of said tobacco is less than about 6.5.  
     
     
         31 . A process according to  claim 30 , wherein said pH of said acid is less than about 5.5.  
     
     
         32 . A process according to any one of the preceding claims, wherein the ratio of the percentage reduction in nitrosamines to the percentage reduction in nicotine is in the range of about 1.1:1 to about 18:1.  
     
     
         33 . A process according to  claim 32 , wherein said ratio is in the range of about 1.3:1 to about 10:1.  
     
     
         34 . A process according to  claim 33 , wherein said ratio is in the range of about 2:1 to about 6:1.  
     
     
         35 . A process according to any one of the preceding claims, wherein a suitable mass flow rate of said supercritical fluid extraction medium per kg of tobacco is about 1-55 kg/h.  
     
     
         36 . A process according to  claim 35 , wherein said mass flow rate is in the range of 10-40 kg/hr.  
     
     
         37 . A process according to  claim 36 , wherein said mass flow rate is in the range of 15-35 kg/hr.  
     
     
         38 . A process according to  claim 37 , wherein said mass flow rate is about 30 kg/h.  
     
     
         39 . A process according to any one of the preceding claims, wherein said tobacco treated in accordance with said process is cut tobacco and/or whole leaf tobacco, tobacco dust or reconstituted tobacco.  
     
     
         40 . A process according to any one of the preceding claims, wherein said tobacco is subjected to a microbial deactivation process.  
     
     
         41 . A process according to  claim 40 , wherein said microbial deactivation process comprises a pasteurisation process.  
     
     
         42 . A process according to  claim 41 , wherein said tobacco is heated to a temperature in the range of about 70° C. to about 150° C. for a period of between 30 seconds to 2 minutes.  
     
     
         43 . A process according to  claim 41 , wherein said pasteurisation process is effected by heating of said tobacco by convection heating by way of contacting said tobacco with a gaseous heating medium, by microwave heating or by radio frequency heating.  
     
     
         44 . A process according to any one of claims  40 - 43 , wherein the moisture content of said tobacco being subjected to said microbial deactivation process is adjustable by way of either a pre- or post-conditioning step.  
     
     
         45 . A process according to  claim 41 , wherein said microbial deactivation process comprises use of ionising radiation, UW radiation, freeze drying or an electron beam.  
     
     
         46 . A process according to any one of claims  1 - 45 , wherein said tobacco is subjected to nitrite/nitrate removal process, before, during or after treatment of said tobacco with said supercritical fluid.  
     
     
         47 . A process according to  claim 46 , wherein said nitrite/nitrate removal process comprises the steps of solvent extraction to remove nitrites/nitrates from said tobacco followed by ion exchange to bind said nitrites/nitrates.  
     
     
         48 . A process according to  claim 46 , wherein said nitrite removal process comprises an oxidation step or use of micro-organisms.  
     
     
         49 . A process according to any one of claims  46 - 48 , wherein ascorbic acid is applied to said tobacco, incorporated with said supercritical fluid, or incorporated with a chemisorption medium.  
     
     
         50 . A nitrosamine extraction apparatus in use according to any one of the preceding claims, said apparatus being a closed system comprising a first chamber for the treatment of said tobacco with supercritical fluid, a second chamber in which said nitrosamine removal process takes place, said chambers being interconnected by interconnecting means, said apparatus further comprising supercritical fluid supply means supplying supercritical fluid, fluid transfer means operable to cause said supercritical fluid to flow around said closed system, and a nitrosamine removal material residing in said second chamber.  
     
     
         51 . Apparatus according to  claim 50 , wherein said fluid transfer means is a pump.  
     
     
         52 . Apparatus according to  claim 50 , wherein said fluid transfer means is a pressure differential system.  
     
     
         53 . Apparatus according to any one of claims  50 - 52 , wherein a plurality of interconnected chambers are provided for said treatment of said tobacco with supercritical fluid and/or a plurality of interconnected chambers are provided for said nitrosamine removal process.  
     
     
         54 . Apparatus according to  claim 53 , wherein said supercritical fluid flows sequentially through said chambers.  
     
     
         55 . A nitrosamine extraction apparatus in use according to any one of claims  1 - 49 , said apparatus being a closed system, wherein said closed system comprises a chamber having inlet and outlet means connected by interconnecting means, fluid transfer means and nitrosamine removal means.  
     
     
         56 . Apparatus according to  claim 55 , wherein said nitrosamine removal means comprises an ion exchanger or an adsorbent held in a supercritical fluid permeable container within said chamber.  
     
     
         57 . A closed system according to  claim 56 , wherein said interconnecting means serve for the transfer of supercritical fluid extraction medium under the action of fluid transfer means, from said outlet means of said chamber and through a nitrosamine removal process station to said inlet means of said chamber.  
     
     
         58 . A Burley tobacco having an initial nitrosamine content after curing in the range of about 0.3 ppm—about 3.0 ppm, wherein said Burley tobacco has a nitrosamine content that is at least 45% lower following treatment according to the process of any one of claims  1 - 49 .  
     
     
         59 . A Virginia tobacco having an initial nitrosamine content after curing less than 8.5 ppm, wherein said Virginia tobacco has a nitrosamine content that is at least 45% lower following treatment according to the process of any one of claims  1 - 49 .  
     
     
         60 . A Burley or Virginia tobacco according to  claim 59  or  60 , wherein said nitrosamine content is at least 60% lower than the original content.  
     
     
         61 . A Burley tobacco having an initial nitrosamine content of 5-6 ppm, the nitrosamine content after treatment according to any one of claims  1 - 49  being 3.6 ppm or less.  
     
     
         62 . A US blended tobacco having an original nicotine content in the range of 0.10-2.0% and a nitrosamine content in the range of 0.10-0 1.2 μg/g, wherein said blend after processing according to any one of claims  1 - 49  has a ratio of percentage decrease in nitrosamines to percentage decrease in nicotine in the range of 1:1 to 10:1.  
     
     
         63 . A Virginia tobacco blend having an original nicotine content in the range of 0.10-2.0% and a nitrosamine content in the range of 0.10-1.2 μg/g, wherein said blend after processing according to any one of claims  1 - 49  has a ratio of percentage decrease in nitrosamine to percentage decrease in nicotine in the range of 1:1 to 10:1.  
     
     
         64 . A tobacco blend according to  claim 62  or  63 , wherein said ratio is preferably 5:1 or more.  
     
     
         65 . A tobacco blend according to  claim 62  or  63 , wherein said ratio is preferably 8:1 or more.  
     
     
         66 . A tobacco treatment process substantially as hereinabove described with reference to FIGS. 1 and 2 hereof.