Study on sugar-related enzyme in cured tobacco leaves: the effect of curing method on remaining activity
Sugars in cured tobacco leaves are one of the key compounds that bear on the taste/aroma of cigarette smoke. The sugar compositions are known to undergo changes during storage. In previous report, we demonstrated that sucrose also underwent changes during storage, which was mainly caused by an enzymatic reaction (A, Nagai, 67th Tobacco Science Research Conference, 2013). These results revealed the importance of understanding the remaining enzyme activity from a quality control standpoint. In this study, sugar-related enzymes that retain activity in cured leaves are investigated, along with our previous study.
A model test was first carried out to find enzyme activities that affect certain components in cured leaves. Sugar-related substrates, known as tobacco components, were added to the samples, which were then stored. The substrates in some instances changed with time. One sample that had been heat treated before adding a substrate showed no change. These results indicated the possible existence of an active enzyme. Further investigation was conducted using a crude enzyme solution prepared from several leaves. Model substrates reacted in the solution, and each enzyme’s activity could be assayed by calculating the reaction rate. Flue-cured Virginia showed more significant activity of α-amylase and invertase than did burley leaf or oriental leaf. On the other hand, burley leaves showed significant α-glucosidase and β-glucosidase activity. After further investigations it was concluded that a difference in the activity pattern between samples was predominantly affected by the curing method.