Abstract
Objective: The inhibition of lipid oxidation is important for the application of edible fats and oils in food processing. High oleic oils exhibit high stability during oxidation. Hazelnut oil, naturally rich in oleic acid, has recently become widely used in the food industry due to its high oxidation stability. Antioxidants are added to oils to make them more resistant to oxidation. β-carotene is a natural antioxidant and leads to increased resistance to photooxidation. The aim of this work was to investigate the effect of a natural antioxidant β-carotene on light-induced lipid stability of hazelnut oils.
Materials and Methods: The hazelnut oil was supplemented with β-carotene in 25 ppm. Not-supplemented hazelnut oil (HO) and the beta-carotene added hazelnut oil (HO with β-car.) were irradiated in a xenon test instrument by different light intensities at 275 and 765 W/m2 for 2, 4, 6, 8, 10, 12, 18, 24, 30, 36, 42 and 48 hours. Fatty acids from the hazelnut oil samples were determined as fatty acid methyl esters (FAMEs) using GC-FID method. To investigate the degree of oxidation of the hazelnut oil samples, the induction time with an accelerated aging test using a Rancimat, peroxide value, volatile lipid oxidation compounds using SPME-GC-FID and antioxidative capacity using DPPH-radical scavenging assay were measured.
Results: The results indicated that the change in fatty acid composition with irradiation intensity and duration of irradiation is not so strong. Among the fatty acids, a significant change was detected only in the linoleic acid content between the HO and the HO with β-car. after light exposure. The amounts of hexanal, heptenal, E-2,4-heptadienel, nonenal, and nonanoic acid increased after photooxidation. The antioxidant capacity of the hazelnut oil samples decreased during light exposure. After light exposure, HO with β-car. showed a higher induction time and lower peroxide value compared to HO.
Conclusion: These results confirm that the β-carotene supplemented hazelnut oil showed higher oxidative stability than hazelnut oil without additional β-carotene. In conclusion, the results suggest that β-carotene could slow down the photooxidation of hazelnut oil.