Just found this on the web, company sells additives for tobacco but this was interesting:
For the improvement of the taste of the tobacco smoke in the sauces are added sweetening substances in the form of plain sugar, honey, glucose, fruit syrups, fruit pulps etc. For the combustion of their combustion are obtained substances with acid reaction, which neutralize the proteins, nicotine, and the chlorophyll as well as other active alkali stuffs. Also obtained through the combustion, which cause the unpleasant taste of the tobacco smoke. In this way they regulate the smoke pH amounts thus improving the taste qualities and having an indirect effect on the flavor.
What is more, during the combustion caramelization takes place and favorable compositions are formed, which have a positive effect on the flavor. Another important ingredient of the sauces, which contributes for the taste and flavor improvement of the tobacco products are the extracts from various plants and fruits - for example these are extracts from Sweet root (Gluzerizia glabra), extracts from plums, morello cherries, raisins etc. Extracts from different tobacco sorts are also used for the taste and flavor improvement of the tobacco products.
Usually it is the Burley tobacco sort that is sauced but it is possible for the whole tobacco mixture to be sauced. The amount of the sauce is 2 - 6% and depends on the relation between the tobacco sorts in the mixture and on the taste-flavor qualities of the desired type of cigarettes.
Burley tobacco sort is toasted. In some cigarettes blends its content is too big and after the tobacco toasting it is baked in temperature higher than that of the saucing. Special production line is required for the toasting of tobacco.
Of course this relates to commercial production but this website sells small samples to the public.
(edited to add the link) http://www.essentialoils.eu.com/tobacco_sauces.phtml