Process for coating of reconstituted tobacco sheet with citrates

The combustion property and thermal pyrolysis behavior of reconstituted tobacco sheet (RTS) with combustion improvers added to the RTS coatings were studied. The RTS coatings comprised of water-soluble extracts from tobacco stems and leaves, carboxymethyl cellulose and sodium citrate/potassium citrate. The coating was mixed and stirred by a high-speed dispersion machine for 40 min, and then coated on the RTS base paper by papermaking method. Effects of citrates on the properties of RTS, such as major chemical compositions, surface microstructure, tar and carbon monoxide (CO) release per cigarette were investigated. The results showed that adding sodium citrate and potassium citrate in the coatings did not affect the main chemical contents and surface microstructure of RTS. With the ratio of potassium citrate increasing in the coating, the amount of tar and CO release per cigarette decreased significantly. Thermogravimetric (TG) analysis and the corresponding derivative thermogravimetric analysis (DTG) indicated that, compared to sodium citrated, potassium citrate accelerated the thermal degradation of RTS between 200 and 400 °C, and decreased the activation energy (E) according to the kinetic analysis results of Coats-Redfern model. Therefore, potassium citrate may become a potential burning additive controlling CO and tar release in mainstream smoke of RTS.