Highly efficient method for synthesizing difructose anhydride III

A method of synthesizing with high efficiency difructose anhydride III, comprising firstly converting sucrose into inulin by adding inulosucrase without separating polysaccharide, and then converting inulin by adding inulin fructotransferase to synthesize the functional disaccharide difructose anhydride III;

• wherein the amino acid sequence of the inulosucrase is set forth in SEQ ID NO.1;
• wherein the process for converting sucrose into inulin comprises:
• completely dissolving the sucrose in water, wherein the concentration of the sucrose is at 400-500 g/l, regulating pH to be at 5.0-6.0, controlling temperature to be at 20-30° C., adding inulosucrase with an amount of 1-15 U/g of sucrose, and performing thermostatic reaction for 25-60 minutes to obtain a sucrose conversion solution;
• wherein the process for converting inulin into difructose anhydride III comprises:
• heating the sucrose conversion solution to 50-60° C., and adding inulin fructotransferase into the sucrose conversion solution, wherein the concentration of the inulin fructotransferase is at 1-20 U/g of the sucrose conversion solution, controlling the pH to be at 5.0-6.0, and performing thermostatic reaction for 2-12 hours.