辛烯基琥珀酸淀粉酯的醇相法制备及其理化性质

Preparation of Octenyl Succinic Starch Ester by the Alcohol Phase Method and Analysis of its Physicochemical Properties

摘要:

以木薯淀粉为原料，在醇水相中进行预处理，在醇相中进行预处理淀粉与辛烯基琥珀酸酐（OSA）的酯化反应，制备了不同取代度的OSAS，研究了淀粉乳浓度、反应温度、反应pH、OSA用量及反应时间对产物取代度（DS）和反应效率（RE）的影响，并通过正交实验优化制备工艺，得出醇相法制备辛烯基琥珀酸淀粉酯（OSAS）的最佳工艺条件为反应时间4 h，反应温度为35 ℃，OSA用量为30%，pH为8.5，淀粉乳浓度为35%，此时产物DS为0.0889，RE为38.47%。以原木薯淀粉为原料，在该条件下制备的酯化淀粉DS为0.0323，RE为13.98%，表明该预处理能显著提高RE。FT-IR分析表明淀粉分子上成功引入辛烯基琥珀酸基团；XRD测试表明原木薯淀粉经过预处理后结晶度由21.48%下降至8.61%，A型结晶结构部分转化成V型，酯化反应首先发生在淀粉的表面及无定形区，其次进攻淀粉内部及结晶区进而导致结晶度有所下降；淀粉经酯化改性后，糊液粘度、抗凝沉性和透明度明显提高。

Abstract:

Cassava starch, as the raw material, was pretreated in alcohol-water phase, by which esterification reaction between the treated starch and octenyl succinic anhydride (OSA) was facilitated to yield OSASs with different degrees of substitution (DS). The influences of the starch concentration, reaction temperature, pH, dosage of octenyl succinic anhydride and reaction time on DS and reaction efficiency (RE) were studied. The preparation process of OSAS was optimized through orthogonal experiments, and the obtained optimal production conditions were: reaction time 4 h, reaction temperature 35 ℃, OSA dose 30%, pH 8.5, and starch concentration 35%. Under such conditions, the obtained OSAS had a DS of 0.0889 and RE of 38.47%. However, the degree of substitution and the reaction efficiency of esterified starch prepared with original cassava starch under the same condition were 0.0323 and 13.98% respectively, indicating the pretreatment could significantly improve RE. FT-IR analysis showed that the octenyl succinic acid groups were successfully introduced into the starch molecules. XRD analysis showed that the pretreatment made the original cassava starch transform partly from A-type crystal structure to V-type crystal structure, with its crystallinity decreasing from 21.48% to 8.61%. Esterification occurred firstly on the surface and in the amorphous region of starch, and then attacked the crystalline region and the inner structure, causing the decrease of crystallinity. The viscosity, retrogradation and the transparency of starch ester were significantly improved after esterification.