Bull. Spec. CORESTA Congress, Vienna, 1984, p. 42, G03, ISSN.0525-6240

Factors affecting discoloration and carbonization of unmanufactured flue cured tobacco

Universal Leaf Tobacco Co., Richmond, VA, USA
Our previous work indicated that modern advances and trends in the mechanical processing of unmanufactured tobacco were developing conditions which would be favorable for the discoloration, carbonization, and possible pyrogenesis of flue-cured tobacco. We have subsequently focused our investigation on the redrying, prizing, and storage processes. The parameters chosen for this study included the moisture content, packed temperature and packed density of the tobacco and the insulative effects of the packing container as well as the effect of row position in storage. The series of tests were designed around a standard parameter matrix. Data from the redrying and prizing processes were recording for each container of tobacco. The tobacco temperature was monitored every four hours for the first 72 hours and periodically thereafter when conditions so indicated. Samples for color comparison and chemical analysis were taken at the beginning of each test, after 72 hours, an d after any necessary extension. Severe carbonization was found in flue-cured tobaccos with moisture, packed temperature, and packed densities as low as 11%, 40.degree.C, and 0.370 g/cm3 respectively, and sugar contents as low as 12% (moisture free basis). We have documented a variety of parameter combinations which have resulted in progressive degrees of discoloration and carbonization. Key factors identified were packed density, moisture content and substained internal temperature. A model for carbonization is proposed and an extension is made for the pyrogenesis reaction.