Generation of lipid peroxidation products in culinary oils and fats during episodes of thermal stressing: A high field ¹H NMR study

Abstract

The oxidative deterioration of glycerol-bound polyunsaturated fatty acids (PUFAs) in culinary oils and fats during episodes of heating associated with normal usage (30-90 min at 180°C) has been monitored by high field 'H NMR spectroscopy. Thermal stressing of PUFA-rich culinary oils generated high levels of n-alkanals, truna-2alkenals, alka-2,rl-dienals and 4-hydroxy-trans-2-alkenals via decomposition of their conjugated hydroperoxydiene precursors, whereas only low concentrations of selected aldehydes were produced in oils with a low PUFA content, lard and dripping when subjected to the above heating episodes. Samples of repeatedly used, PUFA-rich culinary oils obtained from restaurants also contained high levels of each class of aldehyde. The dietary, physiological and toxicological ramifications of the results obtained are discussed.

Monitoring of heat‐induced degradation of edible oils by proton NMR

“…5 that the aldehydes generated in the different oils submitted to this degradation process, also shown in Tab. 4, are: trans-2-alkenals (doublet (a) at 9.480 and 9.500 ppm) and trans,trans-2,4-alkadienals (doublet (b) at 9.507 and 9.527 ppm); 4,5-epoxy-trans-2-alkenals (doublet signal (c) at 9.535 and 9.555 ppm); 4-hydroxy-trans-2-alkenals (doublet signal (d) at 9.562 and 9.582 ppm); moreover, in oils with a significant level of polyunsaturated acyl groups (such as corn, sunflower, soybean and linseed oils), cis,trans-2,4-alkadienals (doublet signal (f) at 9.586 and 9.606 ppm) whose assignment was made using as standard a mixture of trans,trans-2,4-decadienal and cis,trans-2,4-decadienal, and in addition in agreement with data provided by other authors [17,18,37]; n-alkanals (with wellknown triplet signal (g) centered at 9.748 ppm); other unidentified aldehydes which could be either saturated aldehydes having a small number of carbon atoms or oxo-alkanals (triplet signal (h) at 9.778 ppm) in agreement with different data from the literature [38].…”

“…However, to the best of our knowledge, none of the above studies provide information on the nature and proportions of the different types of aldehydes, including oxygenated a,b-unsaturated aldehydes, generated in oil degradation, and only those 1 H NMR of thermodegraded oils 53 studies carried out by 1 H nuclear magnetic resonance (NMR) spectroscopy are able to give this kind of information simultaneously and directly from the sample without previous separation or chemical change [17][18][19][20][21][22][23]. This technique for monitoring the degradation of edible oils, occurring either at 70 7C with aeration or by microwave action at temperatures below 190 7C, has proved that the nature and proportions of the aldehydes formed depend on both the oil nature and the degradation conditions.…”

Lipid peroxidation of fish oils

“…Dietary consumption of peroxidation products may represent an important risk factor for the induction and development of atherosclerosis in humans (8). In spite of substantial evidences of health benefits of ω-3 fatty acids, consumption of fish oil is unlikely to be suited to lifetime daily use.…”

“…Many humans are continually exposed to oxidized oils and fats in their diet which arise from either shallow or deep fat frying processes and the possibility that regular consumption of such products may be deleterious to human health, has attracted much interest (6)(7)(8). Based on the above reports, it was considered essential to determine the level of thiobarbituric acid (TBA) reactive material (Lipid peroxide level) present in the fish oils available in the market with and without Vitamin E supplementation.…”

Antiserum detection of reactive carbonyl species-modified DNA in human colonocytes

“…A well-established hypothesis for the initiation of colonic neoplasia may be as a result of the oxidation of dietary PUFAs during the cooking process [13] and food storage. Redox cycling food chemicals formed during food processing or present as contaminants [6] can, through an autocatalytic process, initiate peroxidation of PUFA and additionally, lipoproteins present as cellular components of the gastrointestinal mucosa.…”