Formation of Phospholipid Association Colloids in Rapeseed Oil and Their Effect on Lipid Autoxidation in the Presence of Sinapic and Ferulic Acid

This study describes the formation of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) association colloids (reverse micelles) in rapeseed oil and interactions of sinapic and ferulic acids with these structures. Furthermore, the process of oil autoxidation in the presence of DOPC is characterized and the antioxidant efficiency of phenolic acids in the oil containing reverse micelles is determined. Formation of DOPC reverse micelles above the phospholipid critical micelle concentration (51.13 mu mol kg(-1)) is observed. The fluorescence probe emission parameters confirm the interactions of sinapic and ferulic acids with reverse micelles and changes of their structure (reduced rigidity) as a result of phenolic acid incorporation. In the analyzed rapeseed oil, an evident prooxidative effect of DOPC reverse micelles is found, as their presence accelerates decomposition of hydroperoxides to hexanal. The antioxidant effect of sinapic acid is strongly influenced by the presence of DOPC reverse micelles. Ferulic acid shows a concentration-dependent antioxidant effect in relation to the formation of hexanal. Practical Applications: Understanding the influence of sinapic and ferulic acids on the structure of association colloids and rapeseed oil autoxidation in the presence of reverse micelles should facilitate extension of shelf life and reduce oil quality deterioration during storage. This knowledge may also be used to optimize industrial oil refining to provide the desired amount of amphiphilic minor components and native antioxidants. Thus, developed refining using mild conditions or even minimizing the degree of refining is attractive in view of greater retention of health-promoting compounds in vegetable oil, reduction of processing costs, and increased sustainability of the oil-refining process.