Effect of two-stage dehydration on retention of characteristic flavor components of flue-cured tobacco in rotary dryer

Abstract

ABSTRACTTwo-stage dehydration method of flue-cured tobacco in rotary dryer was experimentally evaluated and compared to the single-stage dehydration process. The characteristic flavor components in dried cut tobacco, including major Maillard reaction compounds and carotenoid degradation products, as well as drying rate were analyzed for different two-stage dehydration operations. The results showed that both the pre-drying temperature and intermediate moisture content had a significant effect on the overall drying rate of cut tobacco during two-stage drying. On the other hand, the retention of characteristic flavor components in tobacco, especially Maillard reaction compounds retention, was influenced significantly by the final drying temperature as well as intermediate moisture content. The 10°C increase in the final drying temperature from 100 to 110°C reduced the retentions of Maillard reaction compounds and carotenoid degradation products by 14.5 and 9.4%, respectively. Change of intermediate moisture contents from 19 to 15% reduced the Maillard reaction compounds retention by 14.7%. Given the consideration of characteristic flavor components’ retention and drying process efficiency, two-stage dehydration of cut tobacco in rotary dryer could reach a better performance as compared with the single-stage dehydration. The cylinder-wall temperature combination of 140/100°C with the 17% intermediate moisture content could be used as the optimal two-stage condition for the investigated flue-cured tobacco.