Factors Effecting Discolouration and Carbonization of Unmanufactured Flue-cured Tobacco

Modern advances in the mechanical processing of unmanufactured tobacco have developed conditions which could be favourable for the discolouration, carbonization, and possible pyrogenic reaction of flue-cured tobacco. Severe carbonization has been found in flue-cured tobaccos with moisture, packed temperature, and packed densities as low as 11 %, 40°C, and 370 kg / m³ respectively, and sugar contents as low as 14 % (moisture-free basis). We have focused our investigation on the redrying, prizing, and storage processes. The parameters chosen for this study included moisture content, packed temperature and packed density, and the insulative effects of packing containers as well as the effect of row position in storage. Data from the redrying and prizing processes were recorded for each container of tobacco. The tobacco temperature was monitored every four hours for the first 72 hours after packing and periodically thereafter when conditions so indicated. Samples for colour comparison and chemical analysis were taken at the beginning of each test, after 72 hours in storage and later as necessary. Key factors identified were packed density, moisture content and sustained internal temperature. A model for carbonization is proposed and an extension is made for the pyrogenic reaction.