Influence of fatty acid composition on the formation of polar glycerides and polar fatty acids in sunflower oils heated at frying temperatures.

Abstract

RESUMENInfluencia de la composición de ácidos grasos en la formación de glicéridos polares y ácidos grasos polares en aceites de girasol calentados a temperaturas de fritura.Aceites de girasol convencional y alto oleico así como una mezcla al 50% de ambos fueron calentados a diferentes temperaturas bajo condiciones controladas. Se cuantificaron los compuestos polares totales, los grupos principales de glicéridos, áci-dos grasos polares totales, los grupos principales de ácidos grasos polares y la pérdida de ácidos grasos iniciales.Los resultados más relevantes demostraron la primacía de la formación de compuestos de polimerización glicerídicos durante el calentamiento a altas temperaturas. Después de la transesterificación de las muestras, los ácidos diméricos constituyeron el grupo más significativo de compuestos obtenidos. Como era esperado, el ácido linoleico contribuyó preferentemente en la formación de los ácidos grasos polares, si bien la participación del ácido oleico fue muy importante a bajas concentraciones de ácido linoleico. Finalmente, se obtuvieron buenos resultados estadísticos para la regresión entre ácidos grasos polares y compuestos polares. PALABRAS-CLAVE: Aceite de girasol calentado -Ácidos grasos polares (formación) -Composición de ácidos grasos (influencia) -Glicéridos polares (formación). SUMMARY Influence of fatty acid composition on the formation of polar glycerides and polar fatty acids in sunflower oils heated at frying temperatures.Conventional and high oleic sunflower oils as well as 50% mixture of both of them were heated at different temperatures under well-controlled conditions. Total polar compounds, the main groups of polar glycerides, total polar fatty acids, the main groups of polar fatty acids and the loss of initial fatty acids were quantitated.The most outstanding results demonstrated the primacy of the formation of glyceridic polymerization compounds during heating at high temperatures. After transesterification of the samples dimeric fatty acids was the most significant group of compounds obtained. As expected, linoleic acid was preferentially Part of the Doctoral Thesis of Neuza Jorge to be submitted to Faculdade de Engenharia de Alimentos, Universidade de Campinas, Campinas, Brazil. involved in the formation of polar fatty acids, although the participation of oleic acid became very important at low concentration of linoleic acid. Finally good statistical figures were obtained for the regression of polar fatty acids on polar compounds.

Impact of Frying on Fatty Acid Profile and Rheological Behaviour of Some Vegetable Oils

“…During frying, polyunsaturated fatty acids (PUFA) were decreased and saturated fatty acids (SFA) were increased. It was reported that heat treatment of fats induces modifications of fatty acids with two or three double bonds [19,20]. In our study the level of PUFA tended to decrease, whereas that of SFA increased.…”

Antiradical Performance and Physicochemical Characteristics of Vegetable Oils Upon Frying of French Fries: A Preliminary Comparative Study

“…Arroyo et al. (1995) and Jorge et al. (1997) pointed out that heat treatment of fats induces modifications of fatty acids with two or three double bonds.…”

Chemical and physical properties of a sunflower oil with high levels of oleic and palmitic acids

“…It was then suggested that linoleate could be the primary reactant but the oxidation reactions could propagate readily to all unsaturated species. A study on the formation of polar compounds at frying temperatures [8], indicated that linoleate was preferentially involved in the formation of TAG polymers, although the participation of oleate became very important at low linoleate content.…”