Influences of shredded stem on cigarette properties
Shredding is a process of forcing tobacco stems between counter-rotating toothed blades in a mill where they are stripped lengthwise into thin, fibrous particles. Three types of stems were prepared, namely expanded shredded stem (ESS), expanded cut stem (ECS) and expanded cut rolled stem (ECRS). The impact of the three different stem treatments on mainstream smoke emissions and main physical characteristics of the cigarette as such were investigated. The results showed that: 1) Cigarette containing ESS (ESS cigarette) delivered more tar, nicotine and phenol, less CO and HCN comparing with cigarette containing ECS or ECRS. 2) When the proportion of stem material in cigarette blend was 20%, the deliveries of tar, nicotine and phenol in the smoke of ESS cigarette increased by 6.3%, 11.2% and 10.8%, while the deliveries of CO and HCN reduced by 11.6% and 3.4%, respectively, compared with ECS cigarette. 3) At the same inclusion rate of the respective blend material, the pressure drop and ventilation rate of ESS cigarette were lower, while its firmness was higher than those of ECS and ECRS cigarettes. 4) With the increase of shredded stem length, the CO delivery, pressure drop, ventilation rate and the cigarette ends fall out of ESS cigarette decreased, while the deliveries of tar and nicotine did not change. 5) Drying manner would influence the shredded stem. Compared with cylinder drier, the shredded stem dried by the flash evaporation drier increased the pressure drop, ventilation rate and firmness of cigarette and decreased the deliveries of tar, nicotine and CO in mainstream cigarette smoke.