Effects of leaf drying methods on chemical components found in tobacco leaves

In order to evaluate the effects of drying methods on the chemical contents of tobacco leaves, green tobacco leaves were dried by three experimental methods:freeze-drying, hot air drying and kill-enzyme torrefaction. The chemical contents of selected main leaf components after drying were analyzed. The result showed that the main chemical components in the dried tobacco leaves were more variable by hot air drying and kill-enzyme torrefaction; especially, the pigment contents and polyphenol levels decreased sharply. However, the pigment contents and polyphenol levels in the leaves dried by the freeze-drying method were between several to dozens of times higher than those in leaf treated by the kill-enzyme torrefaction. Therefore, to obtain real variation of pigment and polyphenol levels in tobacco leaves during the curing process, freeze-drying method was recommended.