Evaluation of sunflower oil refinery waste as feedstock for production of sophorolipid

Abstract

Abstract Sophorolipid, a glycolipid biosurfactant, was produced by submerged fermentation using Starmerella bombicola. Sunflower acid oil, waste from a vegetable oil refinery, has been studied as a newer feedstock with glucose for production of sophorolipid. Maximum sophorolipid production was found to be 41.6 g/L at shake flask and 51.5 g/L at fermenter level after 8 days of fermentation. Acidic and lactonic forms of sophorolipid were synthesized using acid oil, with the later being abundant. Structure of purified sophorolipid confirmed with the help of HPLC, LCMS and NMR analysis. The final product was characterized for its surface activity and exhibited equivalent performance when compared with the fresh substrate (oleic acid and sunflower oil) based sophorolipid. The sunflower acid oil based sophorolipid reduced the surface tension of water to 35.5 mN/m and interfacial tension (water/n-heptane) to 0.923 mN/m whereas it reduced to 30.69 mN/m and 5.8 mN/m respectively for synthetic surfactant polysorbate 20. The sunflower acid oil based sophorolipid was also shown to have better emulsification as well as wetting property but less foamability comparatively.