Abstract
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 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.
Highlights
Chemical evaluation of frying fats and oils has been considerably improved in the last two decades due to the emergence of new methodologies quantitating the new compounds formed during the frying process.Determination of polar compounds stands out as the most used analytical method evaluating the total amount of polar glycerides formed by means of adsorption chromatography on silica (Waltking and Wessels, 1981)
High performance size exclusion chromatography (HPSEC) allows quantitation of polymeric glycerides, the most important group of new compounds formed at high temperature, in just 1520 minutes (Perrin etaL, 1984; Wolf etal., 1992)
Combination of adsorption chromatography and high performance size exclusion chromatography (HPSEC) has been very useful for quantitative evaluation of the main groups of new polar glyceridic compounds, i.e., triglyceride polymers (TGP), triglyceride dimers (TGD), oxidized triglyceride monomers and diglycerides (DG) (Dobarganes et al, 1988a)
Summary
Chemical evaluation of frying fats and oils has been considerably improved in the last two decades due to the emergence of new methodologies quantitating the new compounds formed during the frying process.Determination of polar compounds stands out as the most used analytical method evaluating the total amount of polar glycerides formed by means of adsorption chromatography on silica (Waltking and Wessels, 1981). Combination of adsorption chromatography and HPSEC has been very useful for quantitative evaluation of the main groups of new polar glyceridic compounds, i.e., triglyceride polymers (TGP), triglyceride dimers (TGD), oxidized triglyceride monomers (oxTGM) and diglycerides (DG) (Dobarganes et al, 1988a). These methodologies can be applied directly to fats and the analytical information obtained refers to compounds maintaining the glyceridic structure. Through quantitation of fatty acids by gas-liquid chromatography (c) Consejo Superior de Investigaciones Científicas Licencia Creative Commons 3.0 España (by-nc) http://grasasyaceites.revistas.csic.es (GLC), the total amount of polar or altered fatty acids can be indirectly attained (Waltking et al, 1975; Dobarganes etal., 1988b)
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