Analysis of sterols oxidation products (SOPs) in food, by gas chromatography

Sterols have a chemical structure that contains at least one double bond and one tertiary carbon, which make them particularly prone to oxidation during food processing and storage. Sterol oxidation products (SOPs) are structurally very similar and are often present at trace levels, so high-resolution and sensitive analytical methods are required to accurately determine them. A correct identification and quantification of these compounds is necessary, as several adverse biological effects have been attributed to them, especially to cholesterol oxidation products (COPs). The accurate analytical control of sterol-enriched food is also of outmost importance, as plant sterols added therein can easily oxidize, which may contrast their functional cholesterol-lowering properties. This chapter faces the analytical determination of SOPs in food, including the various preparative steps (extraction, cold saponification, purification by solid-phase extraction (SPE)), and the gas chromatographic (GC) analysis with different detectors (flame ionization detector (FID) and mass spectrometer (MS)).