The degradation of bioactive compounds and formation of their oxidation derivatives in refined rapeseed oil during heating in model system

Thermo-oxidative changes were assessed during simulated storage and frying of refined rapeseed oil (RRO). When RRO was heated at 60 and 180 degrees C for 8h phytosterols content decreased by 10 and 40%, however tocopherols disappeared by 7 and 30%, respectively. The oxyphytosterols content increased during first 2 h of heating at both temperatures to 55 and 211 mu g/g, however extended heating resulted in reduction of these compounds to 38 and 169 mu g/g, respectively. Total polar compounds were observed in RRO heated at 60 and 180 degrees C for 8 h at 12 and 42%, respectively. Polar compounds were consisted by: free fatty acids (FFA), low molecular weight (LMW) compounds including monomers, while non-polar fraction contained LMW and monomers formed during heating at 60 degrees C. Non-polar fraction formed during heating of RRO at 180 degrees C for 8h which contained monomers and LMW compounds. Among volatile compounds, four carbonyls and an alcohol were detected in heated RRO.