Abstract: 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.

Key words: rosin acid, starch, enzyme, esterification, NMR

摘要： 以松香和木薯淀粉为原料，二甲基亚砜（DMSO）为溶剂，采用酶催化酯化法在温和条件下制备了取代度0.031～0.092的松香酸淀粉酯，并对其部分理化性质进行了研究。结果表明：松香酸淀粉酯的性能与其取代度密切相关。随着取代度的增大，酯化淀粉产物的可溶指数和溶胀度降低，相对黏度和特性黏度增强，分子链也随取代度的增大而增加。通过对淀粉-碘络合物的紫外光谱分析，发现随着取代度的增大，酯化产物的最大紫外吸收波长向长波长方向移动，且蓝值减小。红外光谱（FT-IR）、核磁氢谱（¹H NMR）、差示热扫描（DSC）、热重差（TGA）和扫描电镜（SEM）对不同取代度的松香酸淀粉酯表征分析的结果表明：酯化产物在1727 cm^-1处产生C O的特性吸收峰，糊化温度及热稳定性相对预处理淀粉有所降低，淀粉颗粒的结晶度下降。

关键词: 松香酸, 淀粉, 酶, 酯化, 核磁共振