Phytosteryl Esters Encapsulated in Liposomes as Bioactive Additives in Mayonnaise

Background: Phytosterols are natural compounds that provide health benefits by lowering LDL cholesterol levels, but they are susceptible to thermo-oxidative degradation during food storage and processing. Encapsulating them in liposomes could increase their stability and bioavailability. The aim of this study was to examine the stability of phytosterols encapsulated in liposomes during heating of mayonnaise at temperatures simulating storage and frying conditions. Methods: Mayonnaise containing 2, 4, 6, and 8% liposomes encapsulating stigmasterol oleate was prepared and heated at 60 °C for 8 h and at 180 °C for 30, 60, 90, and 120 min. The fat content, percentage composition of fatty acids and levels of oleic acid and stigmasterol were determined in each tested mayonnaise. Results: The fat content of mayonnaise with liposomes heated at 60 °C for 8 h was 97–98%. During heating at 180 °C for 60 min, it reached 100%, and after 120 min, it decreased to 75%. The oleic acid content of liposome-enriched mayonnaise remained stable during heating. The greatest loss of stigmasterol was observed in the control sample without liposomes, in which the sterol content decreased 79%. After heating mayonnaise with liposomes, the decrease in stigmasterol ranged from 3 to 25% at 60 °C for 8 h and from 90% to 100% at 180 °C for 90 and 120 min. Conclusions: Enriching mayonnaise with phytosterol esters encapsulated in liposomes can effectively improve the thermal-oxidative stability of plant sterols during short-term heating, but does not protect the product from the loss of these sterols during prolonged, intense heating.