A number of families of compounds are significant contributors to coffee’s aroma. Several sulfur-containing compounds are of importance, including 2-furfurylthiol, with an aroma that on its own is actually commonly described as ‘roasted coffee’. There are also some compounds which on their own might smell pretty unpleasant, but in chorus with the other compounds add nuances to the aroma; for example methanethiol, which has a smell described as like that of rotten cabbage, and which is also a significant contributor to the smell of flatulence. Another sulfur-containing compound, 3-mercapto-3-methylbutyl formate, is brilliantly described as having a ‘catty’ odour in isolation.