In the alcoholic beverages industry, Congeners are substances other than alcohol produced during fermentation. These substances include small amounts of chemicals such as other alcohols (known as fusel alcohols), acetone, acetaldehyde, esters, tannins, and aldehydes (e.g. propanol, furfural, glycols, ethyl acetate). Congeners are responsible for most of the taste and aroma of distilled alcoholic beverages, and contribute to the taste of non-distilled drinks. According to research, bourbon, which has more congeners than vodka, will cause a worse hangover. Single Malt has more congeners than blended Scotch, so it can give a worse hangover. Also, red wine will give you a worse hangover than white because, like other dark coloured drinks, it contains cogeners.