A tobacco treatment process has been developed to remove proteins and polyphenols from cut Virginia tobacco without affecting its bulk physical structure. Proteins and polyphenols in tobacco leaf are thought to be precursors of some nitrogenous and phenolic smoke toxicants respectively. The first step of the process involves aqueous extraction of cut tobacco. The aqueous extract and tobacco fibre are then separated mechanically. The aqueous extract is treated with adsorbents (bentonite to remove proteins, and polyvinylpolypyrollidone to remove polyphenols) and then concentrated. The tobacco fibre is treated with a protease solution to reduce residual protein levels. Rinsing followed by a high-temperature treatment removes and deactivates the enzyme residue. The concentrated tobacco extract is then added back to the fibre and the resulting tobacco is dried to a moisture content suitable for cigarette manufacturing.

Compared with the untreated tobacco blend, a treated flue-cured blend had reduced levels (w/w) of protein nitrogen (59%), chlorogenic acid (33%), rutin (79%), scopoletin (78%) and caffeic acid (53%). Nicotine levels were found to be reduced by 12% while sugar levels increased by 16%. The treated tobacco was made into cigarettes using single segment cellulose acetate filters and with tar yields of 9 mg (ISO/FTC smoking conditions). Mainstream yields of 43 smoke toxicants were measured under ISO smoking conditions. Compared with control cigarettes, cigarettes with treated tobacco gave lower yields of tar (16%), nicotine (17%) and carbon monoxide (20%). Of the 43 toxicants analysed there were significant reductions for some nitrogeneous and phenolic components and also some increases for other constituents.