Identification of Some Volatile Compounds Related to the Flavor of Milk and Cream

Abstract

A low temperature-reduced pressure distillation technique was employed to obtain a total distillate considered to be representative of milk flavor. The carbonyl compounds contained in the aqueous fraction were separated and identified as their 2,4-dinitrophenylhydrazones by paper chromatography, column partition chromatography, ultra-violet spectroscopy, and melting point determinations. Data thus obtained established the presence of formaldehyde, acetaldehyde, acetone, butanone, pentanone-2, and hexanone-2 in milk and cream and presented tentative evidence for heptanone-2 in cream. Quantitative analysis of these individual carbonyl compounds also was performed. The volatile compounds obtained from liquid nitrogen trapping of milk and cream were also investigated. These volatiles were fractionated by gas chromatography and several of the eluted components trapped in liquid nitrogen for mass spectral analysis. The mass spectra data in conjunction with retention times established the identity of ethyl ether, methyl sulfide, acetone, butanone, ethanol, chloroform, acetonitrile, and ethylene chloride. Evidence also was obtained for the presence of a waxy, nut-like odor which is highly characteristic of cream. Its identification awaits further study. © 1962, American Dairy Science Association. All rights reserved.