Aging mechanisms of oil-in-water emulsions based on a bioemulsifier produced by Yarrowia lipolytica

The aging mechanisms of oil-in-water emulsions prepared with Yansan, a bioemulsifier produced by a Brazilian wild strain of Yarrowia lipolytica, IMUFRJ 50682, in glucose-based fermentation medium, were studied and compared with those prepared with Gum Arabic. Oil-in-water emulsions obtained by combining three different organic phases, perfluoro-n-hexane, n-hexadecane and toluene, with two aqueous buffers of different pH, and two bioemulsifiers, were studied through the evolution of the mean droplet size. The emulsions were prepared by sonication and their droplet size distribution was followed for 60 days at 301 K using image analysis. The results indicate that the aging mechanisms of the studied emulsions depend mainly on the bioemulsifier and on the pH of the medium. It is shown that the emulsions containing Gum Arabic age by coalescence while Yansan-based emulsions change their aging mechanisms from coalescence at pH 3 to molecular diffusion at pH 7.