1. Steam distillates containing the flavouring substance(s) from Cheddar cheese were examined chemically. After the volatile fatty acids had been removed, the only substances identified in the flavour concentrates were ethanol, butyraldehyde, ethyl acetate and ethyl butyrate. None of these compounds appeared to be connected with the cheese flavour.
2. The essential flavour compound(s) could not be identified but some of its properties were elucidated.
3. The findings of other workers that the lower volatile fatty acids, diacetyl and acetyl methyl carbinol contribute to Cheddar-cheese flavour could not be confirmed. Flavour tests with numerous other compounds failed to show that they contributed to the typical flavour of Cheddar cheese.
The author gratefully acknowledges the helpful criticism and advice of Dr H. R. White-head throughout the investigation.