Oxidation of sunflower oil during storage

Abstract

Effects of temperature and oxygen concentration on oxidative deterioration during storage of crude sunflower oils, obtained by pressing and solvent extraction, 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: peroxide value, p-anisidine value, free fatty acids, weight gain, total content and distribution of polar compounds, and composition of fatty acids. Extracted 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 series reactions was developed to represent oxidation rate in terms of peroxide value, the reaction rate constants and their temperature dependence being evaluated by nonlinear regression. Finally, good correlations between the percentage of polar compounds or oxidized triglyceride monomers and the peroxide value were found.

Quantitative trait locus analysis of unsaturated fatty acids in a recombinant inbred population of soybean

“…Oleic, linoleic and linolenic fatty acids are unsaturated fatty acids which may benefit human health. However, polyunsaturated linoleic and linolenic fatty acids are susceptible to the oxidation process, which negatively affects the stability and flavor of the oil (Crapiste et al 1999). Hydrogenation of polyunsaturated fatty acids increases the oxidative stability and quality of soybean oil.…”

Effectiveness of added natural antioxidants in sunflower oil

“…In addition, some antioxidants can have more than one mechanism of action. Research has been conducted to find out the antioxidant properties and to better understand the mechanism of oxidation and antioxidant action in lipids (Frankel, 1996;Kamal-Eldin and Appelqvist, 1996;Niki, 1996;St Angelo, 1996;Frankel, 1998;Crapiste et al, 1999;Grasas y Aceites Vol. 56.…”

“…Nowadays, a methodology based on a combination of adsorption and size exclusion chromatography has been applied to study the alteration of lipids, enabling the joint evaluation of primary and secondary compounds (Márquez-Ruiz and Dobarganes, 1997; Carelli et al, 1998;Crapiste et al, 1999;Márquez-Ruiz et al, 2000).…”

“…However, it should be noted that the use of this index is limited to the early stages of oxidation, in which no significant differences with the control sample were observed (data not shown). The rate of hydroperoxide decomposition increases with temperature and the degree of oxidation, the hydroperoxide concentration reaches a maximum and then decreases at advanced stages of oxidation (Crapiste et al, 1999). TR values showed that DT was the only antioxidant with a protecting effect on the naturally occurring tocopherol.…”

Quantificação de TBHQ (terc butil hidroquinona) e avaliação da estabilidade oxidativa em óleos de girassol comerciais

“…15 Com o objetivo de facilitar estudos envolvendo estabilidade oxidativa em óleos vegetais, adaptou-se a metodologia oficial da AOCS 5 (Ce 6-86), que utiliza sistema gradiente de eluição para determinação simultânea de antioxidantes sintéticos -PG, THBP, TBHQ, NDGA, BHA, Ionox-100 e BHT -através da cromatografia líquida de alta eficiência (CLAE).…”