Volatile compounds of oxidized pork phospholipids

Volatile compounds from oxidized pork muscle phospholipids (PL) were analyzed by a purge‐and‐trap method. Total volatile compounds were highly correlated with thiobarbituric acid‐reactive substances, mainly as a consequence of alkanals. Major compounds of the 32 identified substances were alkanals (6023 ng nonane equivalents/mg PL), followed by 2‐alkenals (514 ng nonane eq/mg PL) and 2,4‐alkadienals (368 ng nonane eq/mg PL). Hexanal (4850 ng nonane eq/mg PL) was the major compound from the oxidation of n‐6 fatty acids (mainly linoleic and arachidonic acid). Volatile compounds from the oxidation of n‐3 fatty acids were only minor and included 2,4‐heptadienal (45 ng nonane eq/mg PL) and 2‐pentenal and 2‐hexenal (49 ng nonane eq/mg PL). Finally, nonanal, a degradation compound from oleic acid, was present at a low level (200 ng nonane eq/mg PL) and remained constant during oxidation, which confirmed that monounsaturated fatty acids were stable toward metal‐catalyzed oxidation. With the exception of ester compounds, identified volatiles were qualitatively similar to those obtained in simpler systems, such as fatty acids or vegetable oils. Quantitatively, the volatile compound composition reflected the fatty acid composition of PL.