VOLATILE COMPOUNDS OF OXIDIZED PORK PHOSPHOLIPIDS

Volatile compounds from oxidized pork muscle phospholipids (PL) were a nalyzed by a purge-and-trap method. Total volatile compounds were high ly correlated with thiobarbituric acid-reactive substances, mainly as a consequence of alkanals. Major compounds of the 32 identified substa nces were alkanals (6023 ng nonane equivalents/mg FL), followed by 2-a lkenals (514 ng nonane eq/mg FL) and 2,4-alkadienals (368 ng nonane eq /mg FL). Hexanal (4850 ng nonane eq/mg FL) was the major compound from the oxidation of n-6 fatty acids (mainly linoleic and arachidonic aci d). Volatile compounds from the oxidation of n-3 fatty acids were only minor and included 2,4-heptadienal (45 ng nonane eq/mg FL) and 2-pent enal and 2-hexenal (49 ng nonane eq/mg FL). Finally, nonanal, a degrad ation compound from oleic acid, was present at a low level (200 ng non ane eq/mg FL) and remained constant during oxidation, which confirmed that monounsaturated fatty acids were stable toward metal-catalyzed ox idation. With the exception of ester compounds, identified volatiles w ere qualitatively similar to those obtained in simpler systems, such a s fatty acids or vegetable oils. Quantitatively, the volatile compound composition reflected the fatty acid composition of FL.