Phytosterol oxidation products (POP) in foods with added phytosterols and estimation of their daily intake: A literature review

To evaluate the content of phytosterol oxidation products (POP) of foods with added phytosterols, in total 14 studies measuring POP contents of foods with added phytosterols were systematically reviewed. In non-heated or stored foods, POP contents were low, ranging from (medians) 0.03-3.6 mg/100 g with corresponding oxidation rates of phytosterols (ORP) of 0.03-0.06%. In fat-based foods with 8% of added free plant sterols (FPS), plant sterol esters (PSE) or plant stanol esters (PAE) pan-fried at 160-200 degrees C for 5-10 min, median POP contents were 72.0, 38.1, and 4.9 mg/100 g, respectively, with a median ORP of 0.90, 0.48, and 0.06%. Hence resistance to thermal oxidation was in the order of PAE > PSE > FPS. POP formation was highest in enriched butter followed by margarine and rapeseed oil. In margarines with 7.5-10.5% added PSE oven-heated at 140-200 degrees C for 5-30 min, median POP content was 0.3 mg/100 g. Further heating under same temperature conditions but for 60-120 min markedly increased POP formation to 384.3 mg/100 g. Estimated daily upper POP intake was 47.7 mg/d (equivalent to 0.69 mg/kg BW/d) for foods with added PSE and 78.3 mg/d (equivalent to 1.12 mg/kg BW/d) for foods with added FPS as calculated by multiplying the advised upper daily phytosterol intake of 3 g/d with the 90% quantile values of ORP. In conclusion, heating temperature and time, chemical form of phytosterols added and the food matrix are determinants of POP formation in foods with added phytosterols, leading to an increase in POP contents.