Levan produced by Bacillus subtilis AF17: Thermal, functional and rheological properties

The thermal properties, emulsification, and rheological properties of exopolysaccharides (levan-BS) of Bacillus subtilis AF17 were studied and compared with those of the xanthan gum. The carbohydrate content of levan was more than 95.5% and no proteins were detected. The glass transition temperature was 31.1 °C. Levan-BS displayed a crystallization temperature of 88 °C and melting temperature was about 214 °C. Levan-BS produced more stable emulsions with olive oil and toluene, compared to xanthan gum, at an optimum concentration of 0.8%. The levan solution showed a pseudoplastic non-Newtonian fluid behavior. Levan-BS has several potential features, including high thermostability, good emulsifying properties and stability making it promising to be used in different industrial fields.