Oxidative stability of phytosterols in some food applications

The oxidative stability of phytosterols as lipid compounds can be defined as their resistance to oxidation and thus the formation of phytosterol oxidation products. We studied the oxidative stability of phytosterols during processing and long-term storage in phytosterol-enriched milk powder and heat-treated milk, and in microcrystalline phytosterol suspensions in different fats and oils. All of these food applications were observed to be stable despite the heat treatments used in their processing and the long-term storage even at slightly elevated temperatures. The largest change in the phytosterol oxide content was determined for phytosterol-enriched milk powder stored at 38 degrees C for 12 months. During this period the percentage of phytosterol oxidation grew from 0.03 to 0.07%. Based on our observations, we concluded that food applications tested here were unlikely to represent an important source of phytosterol oxides. Furthermore, the formation of phytosterol oxides did not seem to be limiting factor for manufacture and subsequent storage of these products.