Autoxidation of Milk Lipids. I. Identification of volatile Monocarbonyl Compounds from Autoxidized Milk Fat

The C1 through C1o n-alkanals, the C~ through Cll alk-2-enals, and acetone were conclusively identified as 2,4-dinitrophenylhydrazones, from the volatile material of milk fat oxidized to a TBA No. of 15 and a peroxide value of 14.3. In addition, presumptive evidence is presented for the identification of but-2-enal and the odd-numbered C5 through C1~ n-alkan-2-ones. Approximately 63% of the isolated monocarbonyl compounds were n-a]kanals and 34% alk-2-enals. The possible origin of the identified compounds, their role in the oxidized flavor of milk fat, and the relationship of the results of this paper to the findings of other workers are discussed.