Methods of treating cut stem tobacco material

A method of treating cut stem tobacco material comprising:

• (a) a first expansion step expanding a starting cut stem tobacco material to provide a first expanded tobacco material having a fill value at least about 10% greater than the fill value of the untreated cut stem tobacco material when measured at a normalized moisture content of 14.5% oven volatiles (OV);
• (b) a second expansion step expanding the first expanded tobacco material by intermittently contacting the first expanded tobacco material with a heated surface, wherein the first expanded tobacco material is agitated by a heated screw mechanism to provide a second expanded tobacco material having a moisture content from 0 to about 10% OV and a fill value at least 5% greater than the fill value of the first expanded tobacco material when measured at a normalized moisture content of 14.5% OV;
• and
• (c) adjusting the moisture content of the second expanded tobacco material from about 10% to about 20% OV to provide an expanded cut stem tobacco product,
• wherein the fill value of the expanded cut stem tobacco product is at least 50% greater than the fill value of the starting cut stem tobacco material when measured at a normalized moisture content of 14.5% OV, and
• wherein the heated screw mechanism comprises a helical surface encircling a shaft which is rotated, the helical surface being configured to scoop up and lift at least a portion of the tobacco material being treated as the screw mechanism rotates, to carry the tobacco material and then to allow it to fall away from the screw, so that the tobacco material is in direct and continuous contact with the heated surface for a period of up to about 5 seconds.