Study on Preparation for Cassava Starch Acetate with Low Degree of Substitution Using Mechanical Activated Cassava Starch

The cassava starch acetate of low degree of substitution were preparation using mechanical activated cassava starch which was mechanical activated for half an hour and the native starch as material acetic anhydride as acetylation reagent and sodium hydroxide as catalyst. The effects of reaction temperature, the reaction time, acetic anhydride amount and pH value on esterification of cassava starch were investigated respectively by using degree of substitution(DS) and reaction efficiency(RE)of starch acetate as evaluating parameter. The results showed that reaction temperature,thereactiontime,aceticanhydrideamountandpHvaluehadcertaineffectonthe DSandtheRE of starch acetate. Mechanical activation can significantly increase the DS and the RE of starch acetate. The optimal technical conditions were obtained as reaction temperature 30 ℃, reaction time 40 minutes, acetic anhydride amount0.15 mL, pH value 8.5. Under the conditions, the DS in the products was 0.075, and the RE was 87.45 %.Furthermore, the structure of activated starch and the starch acetate were further characterized by using FTIR.