| Benzo [a] pyrene is the main harmful composition in tobacco smoke, phenols and sterols are considered the main precursor compounds of benzo [a] pyrene. The release amount in reconstituted tobacco smoke is much lower than natural, generally believed that the main reason why the benzo [a] pyrene decrease in reconstituted tobacco smoke is the reduce of precursor compound of harmful gas.This paper mainly study the major harmful ingredients (benzo [a] pyrene) in reconstituted tobacco smoke, summarized the changes of precursor compound in the production process by means of tracked analysis the contents of benzo [a] pyrene major precursor compound (sterol and phenolic) in the critical process. According to the production process parameters calculated precursor compounds content in each stage, analysis of reasons for the change of content and summed up the law, in each process stage, Phenols and sterol in liquid phase lost about 50% and 40% respectively, sterol and phenolic compounds in liquid content stability is poorer, content changes over process conditions. Therefore, select the end of liquid phase-coating liquid, implementation process improvement, added radical blocking/inhibitors and solvent extraction in the coating solution. The impact on the reconstituted tobacco process is minimum, and the resulting products obtained performance uniform and stable. Finally, evaluated the tobacco physicochemical and smoke index of trial samples, Filter out the technical solution that benzo [a] pyrene emissions significantly lower than control samples, and physicochemical index similar or better.The results show that:(1) Phenols mainly exist in liquid phase in the entire process of the reconstituted tobacco. Phenols transferred to extracting solution in the extraction stage, the extract content of phenolic compounds as raw materials 97.1%. After concentration, phenols in the coating liquid are about 89.7% of total phenols as raw material. After beating and paper-making, the phenols decreased sharply and only about 0.9% phenols compounds in the coating phase loss is bigger, mainly because of phenol under the high temperature oxidation decomposition,48.7% of phenols were lost in coating phase, Eventually the phenols in reconstituted tobacco leaf as raw material in the remaining 41.9% of the total phenols.(2) In the main phase of paper-making reconstituted tobacco stages, extraction, concentration, beating, blending and papermaking stage, the contents of total sterols are all decreased, the total decreases of sterols were equivalent to 64.72% in tobacco material. Among them, the extraction and concentration stage, sterols content are decreased, decreased by the equivalent of 21.35% and 15.13% of the total raw material sterol; In beating and papermaking stages, the decreases of sterols are equivalent to 14.06% and 14.18% of the total sterols in raw material; In blending stage, sterol content in low concentration pulp increased, accounted for 10.64% of total sterol in raw material; In the other process stages, the contents of the sterols did not changed obviously. Finally, the measured values of the sterols in the final reconstituted tobacco products is equivalent to 48.67% of the total sterols in raw material.(3) The comprehensive evaluation of reconstituted tobacco is based on the effect of benzo [a] pyrene release, combined with the physical and chemical properties and the other smoke index, the quality of reconstituted tobacco is evaluated, which coating liquid adding additives or organic solvent extraction. Experiment scheme is selected which benzo [a] pyrene reduce more, tobacco quality well, process effect little.The experimental scheme are as follows:2% potassium nitrate added in the coating solution, the benzo [a] pyrene in the flue gas reduces by 41.64% . Coating liquid/petroleum ether and Coating liquid/hexane by petroleum, in the condition that volume ratio of 1:2, ultrasonic extraction of 30 min, the contents of benzo [a] pyrene is decreased by 39.87% and 35.37% in flue gas. |
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