| Summary: | The objective of this research was to study the radiolysis of polyunsaturated lipid systems and to provide data for the development of irradiation detection methodology for seafood. Polyunsaturated triacylglycerols and methyl esters, and mackerel lipids were irradiated with $\gamma$-rays from $\sp{60}$Co at ambient temperature. Radiolytic compounds were collected, fractionated, and identified using vacuum distillation, gas chromatography, and mass spectrometry. In large part the same major radiolytic hydrocarbons produced from the saturated fatty acids, i.e. $\rm C\sb{n-1},\ C\sb{n-2+db},\ C\sb{n-1+db},\ and\ C\sb{n-2},$ were also produced from the polyunsaturated systems suggesting that the primary events are the same, i.e. preferential scission at sites near the ester carbonyl producing specific alkyl, acyl, acyloxy, and acyloxy-methylene free radicals. Several polar compounds including the methyl and ethyl esters, cyclobutanones and other ringcontaining structures have also been identified as radiolytic products from polyunsaturated systems. The yield of radiolytic products from polyunsaturated chains was significantly less than that from saturated systems, suggesting a reduced cleavage along the fatty acid chain due to the stability of C=C and bonds alpha to these, while cleavage of C-H bonds beta to unsaturated linkages are favored leading to non-volatile products. The large number of strictly radiolytic compounds provides sufficient data for the development of radiation detection methodology for seafoods.
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