Whiskies and other distilled beverages such as cognac and rum are complex beverages containing a vast range of flavouring compounds, of which some 200 to 300 can be easily detected by chemical analysis. The flavouring chemicals include "carbonyl compounds, alcohols, carboxylic acids and their esters, nitrogen- and sulphur-containing compounds, tannins and other polyphenolic compounds, terpenes, and oxygen-containing heterocyclic compounds" and esters of fatty acids.[24] The nitrogen compounds include pyridines, picolines and pyrazines.