In this lecture, the most recent techniques applied for the quantitation of the new compounds formed during frying are presented. Given the complex mixture of alteration compounds formed during heating of oils at frying temperatures, quantitation of groups of compounds has been shown to be more practical than specific analysis of individual structures. High-performance liquid-chromatographic techniques, mainly based on the molecular size of the new compounds formed, enable rapid determination of total oligomeric compounds, while a previous separation by adsorption chromatography of the less polar compounds, i.e., intact triglycerides, allows the determination of oxidized, polymerized and hydrolytic compounds. Methodologies applied directly to the fat or to its simpler derivatives - fatty acid methyl esters - are described and applications discussed. At present, a more detailed quantitation of the main oxidized fatty acyl groups included in glyceridic molecules is feasible. In this context, quantitation of short-chain compounds, originally attached to the glyceridic backbone, resulting from hydroperoxide breakdown, as well as epoxy, keto and hydroxy fatty acyl groups by capillary gas-liquid chromatography, is detailed. Finally, present possibilities of high-temperature gas chromatography for determination of oxidized fatty acids and dimers are commented.

Trabajo presentado en el 101st AOCS Annual Meeting and Exposition, celebrado en Phoenix, Arizona (Estados Unidos) del 16 al 19 de mayo de 2010.