THE occurrence of diacetyl and/or acetoin (2-hydroxy-3-butanone) among the volatile components of chicken heated for prolonged periods under oxidation-favoring conditions was reported by Pippen, Nonaka, Jones and Stitt (1958). Recently, Pippen and Nonaka (1959) established that diacetyl and/or acetoin occurs as one of the most abundant volatile carbonyl compounds in fresh, good-quality chicken cooked in water under more or less normal conditions. In the studies mentioned above, a distinction between diacetyl and acetoin was not made, because both compounds give identical bis-2,4-dinitrophenylhydrazones. The objective of the study described here was to determine the amount of diacetyl and acetoin in water extracts of chicken, to determine the relation between heating and the amount of these compounds in aqueous extracts of chicken, and to make an interpretation of these results in terms of flavor significance. METHODS Diacetyl was determined by the method of Prill and Hammer (1938). Acetoin was determined in a …