| Multiply-modified starch ester was prepared under the microwave conditions. The starch sulfate was synthesized with corn starch and sulfating agent. At the same time, the starch sulfate was applied as the substrate to synthesized sulfate selenite. The research studied the conditions of making sulfating agent, at the same time optimized the preparation conditions. The paper also studied the changes of microwave,pH and starch milk concentration respectively which affects the degree of substitution(DS). On the basis of single factor, response surface analysis was done with design expert 6.0 and interactive effects of different factors on the degree of substitution(DS) were studied. The optimistic reaction condition of synthesizing the final product was nNaHSO3/nNaNO2 = 4.30, the temperature of making sulfating agent was 88℃, the time of making sulfating agent was 98min, under these conditions the degree of substitution (DS)of starch sulfate esters could up to 0.558. The conditions of sulfating agent were fixed, estertification conditions were pH = 8.0, starch milk concentration was 38%, microwave reaction power was 743W, microwave reaction time was 73min, microwave reaction temperature was 53℃, the degree of substitution of the starch sulfate reached to 0.615. Using the starch sulfate as the substrate to produce the starch selenite, the results as follows, the adding amount of selenium agent was 1.0g, the degree of substitution of starch sulfate ester was 0.615, the microwave power was 700W, the microwave time was 60min, and the microwave temperature was 40℃, under the condition of this expertment, the final product contain the orangic selenium was 56.1mg/g, Se reaction efficiency reach to 5.6%.After esterification, the SEM results demonstrated that the reaction mainly occurred at the amorphous areas of starch granules, the destroied was just happened on the surface of the starch granules. According to the IR spectra analysis, the esterification didn't destructured the basic sketon of native corn starch, However the esterification reaction brings some changes to the spectrogram of native corn starch, appearing some special absorb vibration peak which belong to S=O,C-O-S and Se=O. We can observed though the X-ray about starch sultate and selenite, it's still remain the A style which the native maize starch inhered. As can be seen by DSC and TG spectrogram, we can got the information that the themral stability of both starch esters were improved.The experiments also did the further analysis about the two kinds of esterification modified starch paste characteristics, the transparency of the paste,the freeze-thaw stability of the paste and the resistence of the retrogradtion were improved though esterification. The results showed that the high temperature stability and acid resistance ability were improved. We also did some research about the realationship between the paste characteristics and the degree of substitution(DS), the results showed that the basic characteristics of the original starch significantly improved. Paste viscosity decreased significantly, freeze-thaw stability, anticoagulant ability has been enhanced. With the degree of substitution increases, the transparency of starch sulfate was enhanced and the anticoagulation was improved, the efficiency of selenium reaction also enhanced.
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