A DSC study of the autoxidation of chia and sunflower oil blends

GUIOTTO, E. N.; IXTAINA VANESA Y; NOLASCO SUSANA M; TOMÁS MABEL C

Long Beach

Congreso; 103rd AOCS Annual Meeting & Expo; 2012

AOCS

Differential scanning calorimetry (DSC) was applied to study the thermoxidation of chia - sunflower oil blends. The thermoxidation of sunflower oil, chia oil -rich in omega-3 fatty acids- and their mixtures (sunflower:chia 80:20 and 90:10 wt/wt) were investigated under non-isothermal conditions (10 - 350ºC) under an oxygen atmosphere at different heating rates (B = 2.5; 5.0; 10.0; 15.0 and 20.0ºC/min). The thermograms showed two peaks associated with the primary and secondary lipid oxidation products. Temperatures of the extrapolated start of oxidation (Te) and the maximum heat flow (Tp1 and Tp2) were determined from each thermogram and used to calculate the activation energy (Ea) and the Arrhenius kinetic parameters of thermal-oxidative decomposition of these oils, using the Ozawa-Flynn-Wall (OFW) method. Chia and sunflower oils recorded the lowest and the highest values of Te, Tp1 and Tp2, respectively. Activation energy (Ea) of the thermoxidation of chia seed oil (onset) was 79.78 kJ/mol and increased up to 88.22 and  89.41 kJ/mol in case sunflower:chia oil blends (80:20 and 90:10), respectively, and up to 99.48 kJ/mol for sunflower oil. This information shows the more susceptibility associated with chia seed oil in terms of oxidation mainly due to its fatty acid composition.