Influence of surfactin on physical and oxidative stability of microemulsions with docosahexaenoic acid.

Docosahexaenoic acid (DHA), one of the most important omega-3 polyunsaturated fatty acids (PUFAs), shows significant health benefits for human beings. In order to stabilize nutrients like DHA, microemulsion is normally used through the addition of surfactant, and surfactin as a natural peptide biosurfactant shows strong surface activity. In this study, we investigated the effects of surfactin on the stability of docosahexaenoic acid single cell oil (DHASCO) microemulsions. The microemusion region was significantly increased with elevated surfactin concentration from 0 to 0.2mmol/L, and reached a maximum. The o/w region of DHASCO microemulsion could significantly increase and the diameters of microemulsion particles were reduced from 140 to 15nm after addition of 0.2mmol/L surfactin into emulsion system. Generally, the physical and anti-oxidation stability of the o/w DHASCO microemulsion with surfactin was highly enhanced. DHA oxidation in microemulsion with surfaction was significantly reduced even stored at 37°C for 60days as compared to non-surfactin. The excellent properties of microemulsion with surfactin could be useful in functional food and medicine.