没食子酸酯化淀粉的合成与特性研究

Study on Synthesis and Properties of Esterified Starch of Gallic Acid

本试验将具有抗氧化功能的没食子酸,通过化学反应转化为三乙酰基没食子酰氯,在10%乙醇条件下与马铃薯原淀粉发生酯化反应,合成没食子酸酯化淀粉,并以紫外分光光度法测定取代度(DS);试验选择原料比、反应温度、反应时间、活化时间及碱添加量进行单因素试验,在单因素结果基础上,正交试验设计对合成工艺参数进一步优化。结果表明最佳合成工艺参数为:原料比1∶1,选取Na_2CO_3为缚酸剂,添加量为2.5%,活化时间0.5h,反应温度为35℃,反应时间为6h,该条件下合成的没食子酸酯化淀粉取代度(DS)为0.22。合成的没食子酸酯化淀粉的结构与原淀粉相比发生明显改变,经4%的乙二胺/甲醇溶液活化后,该变性淀粉的DPPH·自由基清除率为31.6%,光照和pH稳定性较好,但热稳定性较。

In this experiment, the antioxidant gallic acid was converted into triethylgalloyl chloride by chemical reaction. The esterified potato starch was esterified with potato starch under the condition of 10% ethanol. The es- terified starch of gallic acid was synthesized and the degree of substitution （DS） was determined by UV spec- trophotometry. The single factor test was can＇ied out with the ratio of raw materials, reaction temperature, reaction time, activation time and alkali content. On the basis of single factor results, the orthogonal design was further optimized for the synthetic process parameters. The results show that the optimum synthetic parameters are as fol- lows： raw material ratio 1：1, Na2C03 as acid binding agent, adding amount of 2.5%, activation time 0.5h, reac- tion temperature 35℃, reaction time 6h, and the synthesis of esterified starch substitution degree （DS） under this condition is 0.22. The structure of synthetic： gallic acid esterified starch changed obviously compared with the orig- inal starch. After activation of 4% ethylenediamine/methanol solution, the DPPH- free radical scavenging rate of the modified starch was 31.6%, and the stability of light and pH was better, but the thermal stability was poor.