Method for expanding tobacco

Claim 1

The method of expanding tobacco, comprising the step of heating the tobacco to a temperature of not more than 170* F. and concurrently maintaining moisture in said tobacco at a selected level of not more than 0.2 pounds of water per pound of tobacco to thereby increase the flexibility of the cell walls of said tobacco, the pressure on said tobacco being kept sufficiently high during said step to keep the water in the tobacco in the liquid state; reducing the pressure on said heated and moistened tobacco after the cell walls thereof have become plastic to a subatmospheric level of not more than about 1 pound per square inch absolute with sufficient rapidity to cause a part of the water in said tobacco to flash from liquid into vapor, thereby increasing its volume and effecting an expansion in the sizes of the cells in said tobacco; thereafter freezing the water remaining in the tobacco to keep the cells in said tobacco from shrinking by reducing the pRessure on said tobacco to a level of not more than 0.04 pounds per square inch absolute; and thereafter drying the tobacco to reduce the moisture content of the tobacco to a selected level without significantly altering the expanded physical structure of the tobacco by maintaining the pressure on the frozen tobacco at said lower level and heating the moisture in the tobacco to a temperature of at least 20* F. to sublime excess moisture from the tobacco.

Claim 2

The method of expanding tobacco, comprising the step of heating the tobacco to a temperature of not more than 170* F. and concurrently maintaining moisture in said tobacco at a selected level of not more than 0.2 pounds of water per pound of tobacco to thereby increase the flexibility of the cell walls of said tobacco, the pressure on said tobacco being kept sufficiently high during said step to keep the water in the tobacco in the liquid state; reducing the pressure on said heated and moistened tobacco after the cell walls thereof have become plastic to a subatmospheric level of not more than about 1 pound per square inch absolute with sufficient rapidity to cause a part of the water in said tobacco to flash from liquid into vapor, thereby increasing its volume and effecting an expansion in the sizes of the cells in said tobacco; thereafter freezing the water remaining in the tobacco to keep the cells in said tobacco from shrinking by reducing the pRessure on said tobacco to a level of not more than 0.04 pounds per square inch absolute; and thereafter drying the tobacco to reduce the moisture content of the tobacco to a selected level without significantly altering the expanded physical structure of the tobacco by maintaining the pressure on the frozen tobacco at said lower level and heating the moisture in the tobacco to a temperature of at least 20* F. to sublime excess moisture from the tobacco.

Claim 6

The method of expanding tobacco, comprising the step of heating the tobacco to a temperature of not more than 170* F. and concurrently adding water to said tobacco in an amount sufficient to increase the level of moisture therein to a selected level of not more than 0.2 pounds of water per pound of tobacco to thereby increase the flexibility of the cell walls of said tobacco, the pressure on said tobacco being kept sufficiently high during the addition of said water to keep the water in and added to said tobacco in the liquid state; reducing the pressure on said heated and moistened tobacco after the cell walls thereof have become plastic to a sub-atmospheric level of not more than about 1 pound per square inch absolute with sufficient rapidity to cause a part of the water in said tobacco to flash from liquid into vapor, thereby increasing its volume and effecting an expansion in the sizes of the cells in said tobacco; thereafter freezing the water remaining in the tobacco to keep the cells in said tobacco from shrinking by reducing the pressure on said tobacco to a lower level of not more than 0.04 pounds per square inch absolute; and thereafter drying the tobacco to reduce the moisture content of the tobacco to a selected level without significantly altering the expanded physical structure of the tobacco by maintaining the pressure on the frozen tobacco at said lower level and heating the moisture in the tobacco to a temperature of at least -20* F. to sublime excess moisture from the tobacco.

Claim 7

The method of expanding tobacco, comprising the step of heating the tobacco to a temperature of not more than 170* F. and concurrently adding water to said tobacco in an amount sufficient to increase the level of moisture therein to a selected level of not more than 0.2 pounds of water per pound of tobacco to thereby increase the flexibility of the cell walls of said tobacco, the pressure on said tobacco being kept sufficiently high during the addition of said water to keep the water in and added to said tobacco in the liquid state; reducing the pressure on said heated and moistened tobacco after the cell walls thereof have become plastic to a sub-atmospheric level of not more than about 1 pound per square inch absolute with sufficient rapidity to cause a part of the water in said tobacco to flash from liquid into vapor, thereby increasing its volume and effecting an expansion in the sizes of the cells in said tobacco; thereafter freezing the water remaining in the tobacco to keep the cells in said tobacco from shrinking by reducing the pressure on said tobacco to a lower level of not more than 0.04 pounds per square inch absolute; and thereafter drying the tobacco to reduce the moisture content of the tobacco to a selected level without significantly altering the expanded physical structure of the tobacco by maintaining the pressure on the frozen tobacco at said lower level and heating the moisture in the tobacco to a temperature of at least -20* F. to sublime excess moisture from the tobacco.