process is selective for the reduction of secondary alkaloids relative to primary alkaloids additional experiments according to the method of example 1 were carried out using freon 22 chlorodifluoromethane critical point 96 u00b0 c 716 psi instead of carbon dioxide the data are shown in table 2 exemplary conditions for use of freon 22 include 0 to 50 u00b0 c 100 to 2000 psi and a mass of freon 22 to mass of tobacco ratio of 20 to 100 additional experiments according to the method of example 1 were carried out using propane critical point 96 7 u00b0 c 617 psi instead of carbon dioxide the data are shown in table 3 in general the conditions for use of propane are 0 to 50 u00b0 c 100 to 2000 psi and a mass of propane to a mass of tobacco ratio of 20 to 100 the amount of constituents in tobacco may also be reduced using the methods of the invention by employing ethane critical point 32 2 u00b0 c 708 psi or nitrous oxide critical point 36 5 u00b0 c 1046 psi exemplary conditions for use of ethane include 0 to 30 u00b0 c 500 to 2000 psi and a mass of ethane to a mass of tobacco ratio of 20 to 100 exemplary conditions for use of nitrous oxide include 0 to 35 u00b0 c 500 to 2000 psi and a nitrous oxide to tobacco ratio of 20 to 100 the description of the specific embodiments of the methods and tobacco obtained therefrom is presented for the purposes of illustration it is not intended.