β-Sitosterol and campesterol stabilisation by natural and synthetic antioxidants during heating

The aim of this study was to estimate the effect of natural and synthetic antioxidants in protecting phytosterols during heating at 180 °C. Green tea extract, rosemary extract, a mix of tocopherols from rapeseed oil, a mix of synthetic tocopherols, phenolic compounds extracted from rapeseed meal, sinapic acid and BHT were used. After 4 h of heating in oxygen atmosphere β-sitosterol and campesterol oxidation products (7α- and 7β-hydroxysterol, 5α,6α- and 5β,6β-epoxysterol, 7-ketosterol and triols) were estimated by GC. Total content of phytosterol oxidation products in samples ranged from 137 to 374 mg/kg of sample. The effectiveness of antioxidants decreased in the following order: synthetic tocopherols > green tea extract > natural tocopherols from rapeseed oil > rosemary extract > phenolic compounds extracted from rapeseed meal > sinapic acid > BHT.