Comparison of analytical methods for monitoring autoxidation profiles of authentic lipids

Oxidation profiles of polyunsaturated fatty acids, their esters, and fatty alcohols were compared by several commonly employed analytical procedures. The extent of lipid peroxidation varied with the structure of the specific lipid class. The rate of oxidation was greater for polyenoic lipids than for dienoic counterparts. In general, the maximum diene conjugation and thiobarbituric acid reactivity occurred earlier for acids than for esters or alcohols containing identical numbers of carbon chains and double bonds. For each homologous series there were, initially, increasing levels of conjugated dienes and thiobarbituric acid-reactive products, which then diminished in association with rising levels of carbonyl and fluorescent products. At late stages of oxidation, conjugated diene or thiobarbituric acid reactivity was not indicative of total peroxidation products. Thus, supplementary measurements are required to detect secondary degradation products of polyunsaturated fatty acids.