Flavor and Odor Defects of Gamma-Irradiated Skimmilk. II. Identification of Volatile Components by Gas Chromatography and Mass Spectrometry

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Abstract
Compounds from the volatile fractions of samples of skimmilks irradiated 2 x 106 and 5 x 106 rep, sodium caseinate sols irradiated 2 x 106 rep and their respective untreated controls were identified by gas chromatographic and mass spectrometric analyses. Methyl sulfide, acetaldehyde, acetone, butanone, methyl alcohol and ethyl alcohol were identified in the volatiles from skimmilks irradiated at both dosage levels. Methyl mercaptan, methyl sulfide, acetaldehyde, acetone, butanone, and ethyl alcohol were identified in the volatiles from irradiated caseinate sols while acetone was the only volatile compound identified in the control samples. Of the compounds identified, methyl sulfide and acetaldehyde appeared to be the major contributors to the malty defect of irradiated skimmilk whereas methyl mercaptan was of major importance to the putrid-type defect of irradiated sodium caseinate sols. Possible origins and modes of formation of the identified compounds are discussed.