Degradation of phytosterols during storage of enriched margarines

Margarines enriched in plant stanols were stored at two typical temperatures for up to 18 weeks. Analysed margarines contained four phytosterols: brassicasterol, campesterol, sitosterol, avenasterol and two phytostanols: sitostanol, campestanol. The content of phytosterols and phytostanols in margarines changed from 79 mg/g in a control sample to 63 mg/g and 55 mg/g in samples stored for 18 weeks at 4 °C and 20 °C, respectively. At the end of storage, contents of sitostanol decreased by 23% and 30%, while the amounts of oxidised sterols increased by 35% and 100%, respectively, for both temperatures. 7-Hydroxy derivatives dominated among all oxidised phytosterols and their content increased threefold at the end of storage. Epoxy derivatives exhibited a maximum after 6 weeks of storage at 20 °C and thereafter decreased constantly.