It is well known that during frying, oils degrade and give rise to potentially toxic compounds that could migrate to fried food and be absorbed through the diet. In order to preserve oil quality and safety, compounds showing antioxidant capacity are frequently added, such as tocopherols. Nevertheless, most studies investigating their effect are conducted at room temperature or under accelerated storage conditions, which may not accurately reflect their performance at high temperatures, due to the complexity of the frying process. Furthermore, studies carried out under frying temperatures often employ classical methodologies, which offer limited information. To shed light on this topic, the present study addressed the impact of adding a natural Tocopherols Extract rich in gamma-isoform at 0.5 % and 3 % on sunflower oil degradation process under frying conditions in the absence of food, until the legal limit of 25 % of Total Polar Compounds (TPC) was reached. Oil composition was periodically analyzed by Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy and the evolution of viscosity and % TPC in the oil were also assessed.
FRY-001: Addition of Gamma-tocopherol rich Extract: Impact on Sunflower Oil Degradation Process at Frying Temperatures
The results of this study evidenced that the higher the enrichment degree of the oil, the higher the degradation of linoleic acyl groups and the lower the formation of E,E-2,4-alkadienals, E-2 alkenals, alkanals and 4-oxoalkanals. On the contrary, at the highest addition level, the generation of Z,E-2,4-alkadienals and of mono-keto-Z,E and E,E-octadecadienoates was promoted. Regarding polymerization reactions, these were enhanced in the presence of the extract, considering oil viscosity values. Finally, both enriched oils reached the legal limit of 25 % TPC before the non-enriched oil.
Acknowledgments: PID2021-123521OB-I00/ MCIN,AEI/ 10.13039/ 501100011033/ ERDF,UE and EJ-GV IT1490-22. S. A.-P. thanks UPV/EHU for a predoctoral contract (PIF22/35).