Oxidation of sunflower oil during storage

Effects of temperature and oxygen concentration on oxidative deterioration during storage of crude sunflower oils, obtained by pressing and solvent ex traction, were studied. Oxidation was monitored through several analytical and chromatographic methods that determine chemical and physical changes or analyze specific oxidation compounds at different stages of the process, p eroxide value, p-anisidine value, free fatty acids, weight gain, total cont ent and distribution of polar compounds, and composition of fatty acids. Ex tracted oil showed a higher oxidative stability than pressed oil. Oxidative deterioration was strongly dependent on temperature, oxygen availability, and the ratio of exposed surface to sample volume. A kinetic model of two s eries reactions was developed to represent oxidation rate in terms of perox ide value, the reaction rate constants and their temperature dependence bei ng evaluated by nonlinear regression. Finally, good correlations between th e percentage of polar compounds or oxidized triglyceride monomers and the p eroxide value were found. Paper no. J9194 in JAOCS 77, 1437-1443 (December 1999).