羧甲基化改性制备高保水、软凝胶型卡拉胶

Preparation of Carboxymethylated Carrageenan Gels with High Water Holding Capacity and Soft Gelling Property

针对当前高保水、软凝胶的市场迫切需求,本文研究了羧甲基化改善κ-卡拉胶性能。在单因素实验基础上,通过响应面法优化羧甲基化工艺环节,并运用红外光谱扫描、核磁共振探讨其改性机理。结果表明,优化工艺条件为:氯乙酸钠添加量0.02 mol,羧甲基化反应温度65℃、乙醇浓度69%,在此条件下制备改性卡拉胶的析水率为0.16%、凝胶强度为205 g/cm2,与未改性卡拉胶析水率4.60%、凝胶强度2120 g/cm2相比,保水性能和软凝胶性能均极大改善。红外光谱扫描及核磁共振表明,改性卡拉胶的糖单元结构中引入羧甲基官能团,而原有结构未被破坏,因此在析水率有效降低的同时,凝胶强度亦明显降低。

Aiming to adapt the marketable demand for high holding water and soft gel, carboxymethylation was used to improve the properties of K-earrageenan.Based on single factor experiments,the parameters of carboxymethylation were optimized using water separating proportion and gel strength as indexes.The mechanism of modification was discussed by FFIR and NMR.The optimized reaction conditions were：the amount of sodium chloroacetate was 0.02 mol, the temperature of carboxymethylation reaction was 65 ℃ ,and the concentration of ethanol was 69% .Under the conditions, the water separating proportion and gel strength of modified carrageenan was 0.16% and 205 g/cm2, respectively. The properties of holding water and soft gel were better,compared to the un-modified carrageenan, with water separating proportion of 4.60% and gel strength of 2120 g/cm2. FTIR and NMR results showed that, carboxymethyl functional group was introduced into gel structure and the structure was not destroyed, so the gel strength decreased significantly while the water rate was reduced effectively.