Detection, monitoring, and deleterious health effects of lipid oxidation products generated in culinary oils during thermal stressing episodes

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http://www.aocs.org/Membership/informArticleDetail.cfm?itemnumber=40690

November/December 2014
Detection, monitoring, and deleterious health effects of lipid oxidation products generated in culinary oils during thermal stressing episodes
Martin Grootveld, Victor Ruiz Rodado, and Christopher J.L. Silwood

• Trans fatty acids have received considerable attention in the media and the scientific literature (together with their putative atherogenic and carcinogenic actions). The far more toxic aldehydes generated in thermally stressed culinary oils, however, have received little or none.
• The most important chemical reaction involved is the self-sustaining, free radical-mediated oxidative deterioration of polyunsaturated fatty acids (PUFAs), which occurs during the heating of culinary oils (Fig. 1) and, to a much diminished level, saturated fatty acid (SFA)-rich fats. This oxidative degradation process can generate extremely toxic conjugated lipid hydroperoxydienes (CHPDs). These are unstable at standard frying temperatures (ca. 180?C) and are degraded to a broad range of secondary products, particularly saturated and unsaturated aldehydes, together with di- and epoxyaldehydes.
• Such aldehydic fragments also have toxicological properties in humans owing to their high reactivity with critical biomolecules in vivo (proteins such as low-density lipoprotein, amino acids, thiols such as glutathione, DNA, etc.). Despite their reactivities, high levels of CHPDs can remain in PUFA-rich oils which have been subjected to routine frying practices.

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