Analysis of process intensity on tobacco moisture retention based on uniform design
Tobacco moisture retention provides essential information about moisture adsorption behaviour and physical characteristics of cigarette formulating, which also influence cigarette aroma and smoking quality. Effect of the intensity of the casing process on flue-cured tobacco strips was analysed based on uniform design. Isosteric heat, equilibrium moisture content and the monolayer moisture content derived from Guggenheim-Anderson-de Boer (GAB) model of tobacco strips were studied to determine the moisture retentivity with different casing process parameters. Quadratic polynomial regression model and contribution analysis were carried out for understanding correlations between blast temperature, processing time, steam flow compensation and processing capacity and the monolayer moisture content. It was shown that the casing process intensity does affect the moisture adsorption behaviour of flue-cured tobacco and the GAB model was capable of describing the full shape of the water adsorption isotherms of tobacco strips. The synthetic evaluation demonstrated that medium process intensity significantly improved tobacco moisture retention than that with high/weak process intensity. The weak moisture retentivity can probably be attributed to high blast temperature and large steam flow compensation. The study confirmed that medium casing process intensity was the most effective means to improve moisture retention of tobacco strips, thus providing a reliable technical tool for cigarette formulation design and refined processing.