过氧化氢氧化琼脂的制备及其性能表征

Preparation and properties of oxidized agar with H2O2 treatment

中文关键词:  琼脂  过氧化氢  氧化  性质  结构表征

英文关键词:agar  hydrogen-peroxide  oxidation  properties  structure analysis

中文摘要:

      目的 优化低凝胶强度琼脂的制备工艺并研究其相关凝胶性质。方法 以凝胶强度为评价指标, 通过单因素试验和正交试验, 考察反应温度、过氧化氢添加量、反应时间、反应初始pH 对过氧化氢氧化琼脂的影响。结果 确定其最佳工艺条件为: 反应温度80 ℃, H2O2 添加量为2 mL (反应总体积的0.2%), 反应时间4 h, 初始pH 5.0。在此条件下, 氧化琼脂的凝胶强度为249.47 g·cm?2。对原琼脂及氧化琼脂的结构与性质进行表征, 通过红外光谱可发现琼脂经氧化后羧基含量增加, 半乳糖单元上的C-O-C 发生断裂; 热重分析可发现, 氧化琼脂的保水性增强, 而热稳定性降低; 电镜结果显示原琼脂及氧化琼脂均呈不规则颗粒状, 原琼脂经氧化后结构遭到破坏, 表面鳞片状突起均呈不规则塌陷状。结论 经过氧化氢处理后的琼脂分子结构改变,白度及灰分增加, 凝胶温度、融化温度、溶解温度、透明度、粘度值均有降低。

英文摘要:

      Objective To optimize the preparation process of low gel strength agar and discuss its gel properties.Methods Through the single factor test and orthogonal test, the effects of reaction temperature, addition content of H2O2, reaction time and initial reaction pH on the oxidation degree of agar were investigated with gel strength as the evaluation index. Results The optimum conditions for the preparation of oxidized agar were as follows: reaction temperature was 80 ℃, H2O2 content was 2 mL (0.2% of the total volume), reaction time was 4 h, and initial pH was 5.0. Under the optimum conditions, the gel strength of oxidized agar was 249.47 g·cm?2. After then, the structure and properties of native agar and oxidized agar were analyzed contrastively. With the analysis of FTIR spectrograms, the results showed that the -COOH content of oxidized agar was increased and the group of C-O-C on the galactose unit was broken. The water retention of oxidized agar was enhanced and the thermal stability was reduced from thermogravimetric analysis. Observed from the SEM photographs, the raw agar and oxidized agar were irregular particles, after oxidation the structure of the agar was damaged and the surface of the scale-like protrusions was all irregularly collapsed. Conclusion The structure of agar was changed after oxidation of hydrogen, the whiteness and ash content were increased, and the gelling temperature, melting temperature, dissolved temperature, transparency and viscosity were all reduced.