Rosin acid starch esters with degree of substitution (DS) ranging from 0.031 to 0.092 were prepared by enzymatic esterification reaction

using rosin acid and cassava starch as raw material

DMSO as solvent

and its physicochemical characters were also studied. The results showed that with the increase of DS

the swelling power and solubility of esterification products reduced

relative and intrinsic viscosity increased

and the molecular chain of esterified starches grew. The data from UV analysis on the starch-iodine complexes indicated that the maximum absorption wavelength moved to longer wavelength when the DS increases

together with the blue value declines. The rosin acid starch esters with different DS were characterized by FT-IR

1H NMR

DSC

TGA and SEM. The results indicated that the esterified product exhibited a new absorption band at 1727 cm-1

which was assigned to the attribution of the symmetric deformation vibration of carbonyl C O. Compared with the pretreated starch

the gelatinization temperature and thermal stability of rosin acid starch esters were reduced

and the crystallinity also decreased.