Acrolein is a highly polluting contaminant and harmful to humans; constitutes 5% of atmospheric aldehydes2 and, more than FORMALDEHYDE (50% of the TOT), it represents the most dangerous molecule. Some studies conducted by Kane Alare in 1978 they demonstrated that acrolein and formaldehyde act synergistically as COMPETITIVE AGONISTS, therefore the production and severity of mucosal irritations due to atmospheric exposure are to be attributed ESPECIALLY to THEIR concentration (acrolein + formaldehyde) rather than to the total presence of volatile aldehydes.
Despite being quantitatively less present than formaldehyde, acrolein boasts a significantly higher irritant potential; it, even at low concentrations, causes inflammation of the conjunctive mucous membranes of the eyes and the mucous membranes of the airways. Continuous exposure to acrolein causes:

NB. If present in the circulation, acrolein is ALSO potentially toxic to the kidney and certainly highly irritating to the mucosa of the bladder and ureter. This irritation can evolve into erythematous rashes3.

Acrolein in frying oil

Foods with a high acrolein content are especially those that are fried or cooked violently on the griddle or in a pan. Acrolein accumulates in over-used and often already exhausted oils, therefore, the richest food source of acrolein is UNDOUBTEDLY FRIED foods served in mass catering (takeaways, restaurants and fast-food outlets).
The formation of acrolein in foods is determined by exceeding the smoke point, i.e. the temperature above which the oil begins to:

Once the smoke point has been exceeded, the production of acrolein is greater in predominantly unsaturated vegetable oils, especially in those that have a good quantity of polyunsaturated fatty acids (soya, flax, grape seed, walnut, etc. which are therefore not recommended for frying) .
The oil that releases the least acrolein during cooking is undoubtedly PEANUT oil, because it contains 35% polyunsaturated fats, followed by sunflower seed oil (55%). NB. The sunflower seeds intended for the production of oil are genetically mutated to increase the concentrations of oleic acid, consequently raising their smoke point; therefore sunflower seed oil is a potential Genetically Modified Organism (GMO – Skoric D. et al., Can J Physiol Pharmacol 2008)!
However, what needs to be specified is that all seed oils (including peanut oil) undergo a significant release of acrolein after just one frying, therefore they should NOT be used multiple times. On the contrary, virgin (or extra virgin) olive oil also stands out for its good smoke point (thanks to the prevalence of monounsaturated fatty acids) and seems to be able to withstand even 2-3 consecutive fryings; this characteristic is justified by the high antioxidant content which strongly limits the presence of acrolein in the oil.
NB. Seed oils DO NOT contain the same quantities of antioxidants because during industrial processing they are treated with chemical solvents, such as hexane, butane, propane, etc. (Indart A et al. Free Radic Res 2002).
Ultimately it is advisable to limit the frequency of consumption of fried foods to a minimum, especially if PURCHASED elsewhere; Furthermore, to prevent the formation of acrolein at home it is advisable:

  • Respect the smoking point
  • If you use peanut or sunflower oil, use it for a single fry
  • Prefer virgin or extra virgin olive oil

Bibliography:

  1. Chemistry of pharmacologically active heterocyclic compounds – D. Sica, F. Zolfo – Piccin – pag-81:83
  2. Treatise on forensic medicine and related sciences – G. Giusti – page 151-152
  3. Oncology medicine – G. Bonadonna, G. Robustelli Della Cuna, P. Valagussa – Elsevier Masson – page 1764.


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