海藻酸钠没食子酸衍生物的制备及性能分析

以抗坏血酸和过氧化氢为自由基引发剂,使没食子酸与海藻酸钠接枝,赋予海藻酸钠抗氧化性、抑菌性等新的特性。结果表明:当添加过氧化氢和抗坏血酸5.54mmol(摩尔比3.51.0)时,接枝度最高为4.260mg/g。衍生物的红外和拉曼光谱证实了没食子酸成功接枝到海藻酸钠上;差示扫描量热分析发现衍生物的热稳定性改变,扫描电子显微镜分析显示该衍生物表面变得粗糙。当海藻酸钠—没食子酸衍生物浓度为4mg/mL时,对1,1-二苯基-2-三硝基苯肼自由基的清除率达到92.0%,远高于海藻酸钠的清除率,表明衍生物的抗氧化活性显著提高。相比海藻酸钠,该衍生物对车厘子的涂膜保鲜效果更好。

Preparation and properties of sodium alginate-gallic acid derivative

Ascorbic acid and hydrogen peroxide were used as free radical initiators to induce the grafting of gallic acid onto sodium alginate,in order to enhance new properties of sodium alginate such as antioxidation and bacteriostasis,so that it could have potential in food preservation application.Folin-Ciocalteu method was used for determining the grafting degree of sodium alginategallic acid derivative.The results showed that the highest grafting degree was 4.260 mg/g when 5.54 mmol of hydrogen peroxide and ascorbic acid(molar ratio 3.51.0)was added.Infrared and Raman analysis showed that new peaks were appeared in the spectra of the derivative,indicating that gallic acid was successfully grafted onto sodium alginate.Differential scanning calorimetry showed that the thermal stability of the grafted sodium alginate was changed,and scanning electron microscopy showed that the surface of the derivative became rough.When sodium alginate-gallic acid derivative concentration was 4 mg/mL,the scavenging rate of scavenging 1,1-diphenyl-2-trinitrophenylhydrazine radical was 92.0%,which was close to that of gallic acid,far higher than that of sodium alginate.The results showed that the antioxidant activity of the sodium alginate-gallic acid derivative increased significantly.Better preservation of cherries was obtained by the coating of sodium alginate-gallic acid derivative than by the coating of sodium alginate.