Abstract: The microwave etherifying technology was applied to produce phosphate monoester starch(SMEP). The etherifying condition to the substitution(DS) was studied by orthogonal experiment and variance analysis. The results indicated that the successive order of different effect factors on degree of DS of starch phosphate monoester was reaction time > the level of microwave power>pH>quantity of the etherifying agent. The optimum etherification condition was: reaction time 10min., microwave power 900W, pH=6,quantity of the etherifying agent 30%. The variance analysis results was showed that the reaction time had significant influence on DS and microwave power had appreciable influence on DS .The property of the phosphate monoester starch had been studied .The results showed that the phosphate monoester starch property in the paste transparency, apparent viscosity , heat stability, freeze-thaw stability, were remarkable increased and the retrogradation was remarkable weakened. The modified starch property had not advantage in resistance to shearing stress and tolerance to electrolyte (NaCl). Compare with the traditional method,the technology of phosphate monoester starch using microwave is more mildly in reaction conditions and more efficient.The DS and starch paste property with microwave heating under 900W,10min is similar to that with traditional heating under 140℃,120min.

Key words: microwave, phosphate monoester starch(SMEP), degree of substitution, orthogonal experiment, starch paste property