Levels of Phytosterol Oxides in Enriched and Nonenriched Spreads:  Application of a Thin-Layer Chromatography−Gas Chromatography Methodology

The content of phytosterol oxidation products (POPs) in enriched and nonenriched commercial spreads was evaluated by thin-layer chromatography−gas chromatography (TLC-GC). Oxides of β-sitosterol, campesterol, and stigmasterol were produced by thermo-oxidation (7-hydroxy, 7-keto, and epoxy derivatives) and chemical synthesis (triol derivatives), which were then separated and identified by TLC-GC. Their identification was further confirmed by GC−mass spectrometry (GC-MS). The total amounts of phytosterols found were 6.07 and 0.33 g/100 g of sample in phytosterol-enriched and nonenriched spread, respectively, whereas the total POPs contents were 45.60 and 13.31 mg/kg of sample in the enriched and nonenriched products. The main POPs found were the 7-keto derivatives of all phytosterols analyzed; 7-ketositosterol was the most abundant one (14.96 and 5.93 mg/kg of sample in phytosterol-enriched and nonenriched spread). No β-epoxy and triol derivatives were detected in both types of samples. The enriched spread presented a lower phytosterol oxidation rate (0.07%) than the nonenriched one (0.41%). Keywords: Phytosterol-enriched spread; phytosterols oxidation products; functional foods