Preparation of starch succinates by reactive extrusion

The succinylation of cornstarch by extrusion processing has been studied. Several different factors affecting the succinylation of starch were investigated including water content, succinic anhydride quantity, catalyst type and quantity, and reaction temperature. The degree of substitution (DS) increases with decreasing water content and increasing succinic anhydride quantity. Higher temperature favors higher DS using sodium bicarbonate as catalyst while the opposite is true using magnesium hydroxide as catalyst. Of the three catalysts used, sodium bicarbonate is best. Aqueous solubility and viscosity of the starch succinates tend to increase with increasing DS. Based on the results of aqueous solution viscosity, some samples appear to be promising as commercial thickening agent.