Production of a sophorolipid biosurfactant by Wickerhamomyces anomalus MUE24 and its use for modification of rice flour properties

A sophorolipid biosurfactant from Wickerhamomyces anomalus MUE24 was produced upon cultivating in a medium containing soybean oil and glucose with an initial pH of 4.5 at 30 degrees C in shake flask at 200 rpm. After 7 days of cultivation, cells released surfactant into culture medium at 0.55 g/l. The biosurfactant obtained was able to reduce surface tension of the medium from 52.5 mN/m to 36.0 mN/m. A scale up in batch cultivation was further performed in a 5-liter fermenter controlled at 30 degrees C 1 vvm, initial pH 4.5. After 72 h of cultivation, biosurfactant concentration was 19.41 g/l. An extraction from whole cell-containing culture could recover the biosurfactant at 34.06 g/l with a critical micelle concentration of 116 mg/l. Further characterization showed that the crude extract of biosurfactant was able to emulsify various types of vegetable oils such as canola oil, sunflower oil and soybean oil. Addition of the crude extract of biosurfactant into rice flour could improve retrogradation, water-holding capacity and swelling power of rice flour.