Thermal edible oil evaluation by UV-Vis spectroscopy and chemometrics

Edible oils such as colza, corn, sunflower, soybean and olive were analysed by UV–Vis spectroscopy and Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS). When vegetable oils were heated at high temperatures (frying), oxidation products were formed which were harmful to human health in addition to degrading the antioxidants present, and this study aimed to evaluate tocopherol (one antioxidant present in oils) and the behaviour of oxidation products in edible oils. The MCR-ALS results showed that the degradation started at 110 °C and 85 °C, respectively, for sunflower and colza oils, while tocopherol concentration decreased and oxidation products increased starting at 70 °C in olive oil. In soybean and corn oils, tocopherol concentration started to decrease and oxidation products increased at 50 °C. The results suggested that sunflower, colza and olive oils offered more resistance to increasing temperatures, while soybean and corn oils were less resistant.