Abstract: Sanxan is an exopolysaccharide synthesized by fermentation of Sphingomonas sanxanigenens. The acyl groups on the side chain of Sanxanigenens have important influence on the properties of Sanxan gum. In order to investigate the effect of acyl content on the rheological properties of Sanxan gum, deacylated Sanxan gum with different acyl content was prepared by alkali treatment. The content of acyl group in Sanxan gum samples with different alkali treatment time was determined, and the rheological properties of Sanxan gum samples with different acyl group content were studied during room temperature, gelation and melting process. The results showed that although the time of deacylation treatment had little effect on the change of acyl content, the acyl content of trisangel gradually decreased with the extension of the treatment time.The viscosity of natural Sanxan was higher than that of deacylated Sanxan at room temperature. In the process of gelling and melting, the temperature difference of natural Sanxan is larger, and the thermal hysteresis phenomenon is more obvious. In the temperature range of 10 ℃—90 ℃— 10 ℃, the DSC curve of natural Sanxan changes more significantly. The results showed that the existence of acyl group made the double helix structure of Sanxan gum aggregate faster and more stable, which provided a basis for the application, product improvement, technical innovation and popularization of Sanxan gum in food and other fields.

Key words: Sanxan gum, rheology, acyl