Method for whitening tobacco

Abstract

A method of preparing a whitened tobacco material is provided, the method including the steps of (i) extracting a tobacco material with an aqueous solution to give a tobacco solids material and a tobacco extract; (ii) treating the tobacco solids material with a caustic wash to give a tobacco pulp; (iii) bleaching the tobacco pulp with a solution including a strong base, an oxidizing agent, or a combination thereof to give a bleached tobacco pulp; and (iv) drying the bleached tobacco pulp to give the whitened tobacco material. The invention also provides a smokeless tobacco product incorporating a whitened tobacco material. The smokeless tobacco product may be a snus-type formulation contained within a sealed pouch.

What is claimed: 
     
         1 . A method of preparing a whitened tobacco material for use in a smokeless tobacco product, comprising:
 (i) extracting a tobacco material with an aqueous solution to provide a tobacco solids material and a tobacco extract;   (ii) treating the tobacco solids material with a caustic wash to provide a tobacco pulp;   (iii) bleaching the tobacco pulp with a solution comprising a strong base, an oxidizing agent, or a combination thereof to provide a bleached tobacco pulp; and   (iv) drying the bleached tobacco pulp to provide the whitened tobacco material.   
     
     
         2 . The method of  claim 1 , further comprising milling the tobacco material such that the milled tobacco material is able to pass through a screen of 18 U.S. sieve size. 
     
     
         3 . The method of  claim 1 , wherein in the step of treating the tobacco solid material with a caustic wash is done at atmospheric pressure. 
     
     
         4 . The method of  claim 1 , wherein the caustic wash comprises at least one strong base. 
     
     
         5 . The method of  claim 1 , wherein the caustic wash comprises sodium hydroxide. 
     
     
         6 . The method of  claim 1 , wherein the bleached tobacco pulp is dried to a moisture content of less than about 30 percent moisture on a wet basis. 
     
     
         7 . The method of  claim 1 , further comprising hydrolyzing the tobacco pulp with an acid prior to step (ii). 
     
     
         8 . The method of  claim 7 , wherein the acid is sulfuric acid, hydrochloric acid, citric acid, or a combination thereof. 
     
     
         9 . The method of  claim 1 , further comprising dewatering the tobacco material using at least one of a screw press and a basket centrifuge following steps (i), (ii) and/or step (iii). 
     
     
         10 . The method of  claim 1 , wherein the bleaching step (iii) comprises treatment with one or more of peracetic acid, sodium hydroxide, and hydrogen peroxide. 
     
     
         11 . The method of  claim 1 , wherein the bleaching step (iii) further comprises treatment with one or more stabilizers in addition to an oxidizing agent. 
     
     
         12 . The method of  claim 11 , wherein the stabilizers are selected from the group consisting of magnesium sulfate, sodium silicate, and combinations thereof. 
     
     
         13 . The method of  claim 1 , wherein the bleaching step (iii) comprises treatment with a strong base and an oxidizing agent, and wherein the molar ratio of the amount of strong base to the amount of oxidizing agent is from about 1:1 to about 1:100. 
     
     
         14 . The method of  claim 13 , wherein the molar ratio of the amount of strong base to the amount of oxidizing agent is from about 1:5 to about 1:50. 
     
     
         15 . The method of  claim 1 , further comprising neutralizing the bleached pulp material to a pH in the range of about 5 to about 11 prior to step (iv). 
     
     
         16 . The method of  claim 1 , further comprising milling the whitened tobacco material following step (iv) to a size in the range of approximately 5 mm to about 0.1 mm. 
     
     
         17 . The method of  claim 1 , wherein the aqueous solution used to extract the tobacco material in step (i) comprises a chelating agent. 
     
     
         18 . The method of  claim 17 , wherein the chelating agent comprises one or more of EDTA and DTPA. 
     
     
         19 . The method of  claim 1 , wherein the molar ratio of aqueous solution to the tobacco material in the extraction step (i) is from about 4:1 to about 16:1. 
     
     
         20 . The method of  claim 1 , wherein the tobacco material comprises lamina, stems, or a combination thereof. 
     
     
         21 . The method of  claim 1 , wherein the tobacco material comprises Rustica stems. 
     
     
         22 . The method of  claim 1 , wherein the tobacco material comprises at least about 90% by weight roots, stalks, or a combination thereof. 
     
     
         23 . The method of  claim 1 , wherein the whitened tobacco material is characterized by an International Organization for Standardization (ISO) brightness of at least about 60%. 
     
     
         24 . The method of  claim 1 , further comprising mixing the tobacco solids material with a wood pulp prior to step (ii). 
     
     
         25 . The method of  claim 1 , further comprising incorporating the whitened tobacco material within a smokeless tobacco product. 
     
     
         26 . The method of  claim 25 , wherein the smokeless tobacco product further comprises one or more additional components selected from the group consisting of flavorants, fillers, binders, pH adjusters, buffering agents, colorants, disintegration aids, antioxidants, humectants, and preservatives. 
     
     
         27 . A smokeless tobacco product incorporating the whitened tobacco material prepared according to the method of  claim 1 . 
     
     
         28 . The smokeless tobacco product of  claim 27 , comprising a water-permeable pouch containing the whitened tobacco material. 
     
     
         29 . The smokeless tobacco product of  claim 27 , further comprising one or more additional components selected from the group consisting of flavorants, fillers, binders, pH adjusters, buffering agents, colorants, disintegration aids, antioxidants, humectants, and preservatives.